POWDER PROCESSES Powder Metallurgy Alternative Powder Processes Process Design For Powder Metallurgy MANUFACTURING PROCESSES Metal Casting Metal Forming Metal Rolling Metal Forging Metal Extrusion Metal Drawing Sheet Metal
Pressing and sintering are the mechanisms used to form solid parts from powders. Pressing occurs first, then sintering. Before pressing, the powder is fully prepared as explained in the powder metallurgy section. In addition to the powder constituents, binders, deflocculates and lubricants may also be present in the mixture.
Powder pressing, and hence powder forming in general, is best suited to flat parts with 2 dimensional geometry and little thickness. The main problems as part complexity and thickness increase, are higher variations in density due to uneven compaction of powder particles and limitations caused by the need for ejection of the pressed compact. Processing methods are used to mitigate these problems. Process design, the different levels of part complexity and the ultimate capabilities of powder manufacturing are discussed latter, in process design for powder metallurgy. This section covers the conventional powder pressing and sintering technique. Alternative methods of powder manufacturing are discussed in the next section.
Powder pressing is the compaction of powders into a geometric form. Pressing is usually performed at room temperature. This creates a solid part called a green compact. The strength of this pressed, unsintered part, (green strength), is dependent on compactability, binders may be used to increase compactability. Typically a green compact can be broken apart by hand but is also strong enough to be handled, gently. The geometry of the green compact is similar to that of the final part, however, shrinkage will occur during the sintering phase of the manufacturing process and must be calculated in.
Amount of powder needed will be based on the bulk density of the powder and the amount of material in the final part. Bulk density is discussed in the previous section, it is the density of the loose powder by itself. Bulk density is important when measuring powder quantities. The effects of additives such as lubricants must always be calculated. For example, a green compact has a certain amount of lubricants and binders in it that add extra material. During sintering, these lubricants and binders are burned off. Their material is no longer in the part after sintering and this must be a consideration.
To begin the manufacturing process, a certain amount of powder is filled into a die. Rate of die filling is based largely on the flowability of the powder. Powders that flow readily can be poured at higher rates. Pouring can be an automated process.
Once the die is filled, a punch moves towards the powder. The punch applies pressure to the powder, compacting it to the correct geometry. A simple illustration of the pressing process is shown in figure 328.
Punch and die surfaces are very important in powder manufacture. Some clearance between the punch and die must exist in order for the punch to move within the die. Powder particles can become stuck within this clearance, causing problems with the proper movement of machinery. In order to prevent powder particles from becoming lodged within this gap, clearance is designed to be extremely low. Clearance values between punch and die, used for powder pressing, are typically less than .001 inch. Most punch and die are made from hardened tool steels, the surfaces of which are ground then polished, or lapped, in the direction of tool movement. Punches and die for more extreme powder processing operations may be made from tungsten carbide.
Amount of force necessary for a pressing operation is to a large degree based on material. For example, pressing aluminum powder generally requires lower force, while pressing iron powder requires relatively higher force. Pressing force also depends upon powder characteristics, additives and desired density of the green compact. Friction force will oppose movement of particles during pressing, therefore lubrication can reduce the required pressing force and also cause a more uniform distribution of particles during pressing. Lubrication should be applied in the correct quantities. Excessive lubrication will not all remain on particle surfaces, but will also collect in the interparticle spaces, (open pores), and prevent the proper compaction of powder. Pressing force is a function of pressure over the area of the part perpendicular to the direction of pressing. Usually the press is vertical, in this case the horizontal plane of the part would be considered.
Force for industrial powder manufacture typically varies between 10,000 lbs/in2, (70 MPa), and 120,000 lbs/in2, (800 MPa). Parts for this type of manufacture are mostly small, (under 5 lbs), and press requirements are typically under 100 tons. Mechanical presses with capacities on the magnitude of a few hundred tons are usually adequate for most powder processing operations. Hydraulic presses with capacities of several thousand tons are sometimes used for work requiring more force. Double action presses, with opposing top and bottom punches, are commonly used, but for more complex parts multiple action presses may be employed. Punch speed must be regulated. Faster compaction of the work can result in higher productivity, however if the punch speed is too high, air may become trapped in the pores and prevent the part from compacting correctly.
Compaction of a part is dependent upon the actions of the powder particles during pressing. When a powder is first filled into a die it is at its bulk density or the density of loose powder. As the compression of the powder occurs its volume decreases and its density increases, until it reaches the final volume and density of the green compact, (green density). The fully pressed part will still contain porosity and the green density will be lower than the true density of the material.
Interparticle pores and particle surfaces are an important consideration in the pressing of powders. Surface films on the powder particles should be avoided. These materials such as oxides can be rubbed off during pressing and occupy interparticular vacancies, preventing proper compaction of the part. In the first stage of powder pressing density is increased by a rearranging of the individual powder particles. Spaces, bridges and gaps are eliminated, and density increases due to a more efficient packing of the particles. This initial stage provides relatively lower resistance and the density of the powder rapidly increases with applied pressure. Contact points between powder particles become established. As compression continues, increasing forces act between these contact points. Cold pressure welding occurs at contact points between particles. Cold pressure welding is a type of bonding that happens during powder pressing, it helps give the green compact structural integrity so that it may be processed further.
The second stage has no definite starting point but is characterized by plastic deformation of particles. Stress between powder particle contact points causes material deformation. Contact areas are increased, interlocking and plastic flow of particles occurs, volume decreases and density continues to rise. Material movement is increasingly opposed by friction and the work hardening of the metal powder. Unlike the first stage, the rate the density is increasing will decrease as pressure continues to rise. Density will continue to increase until the maximum density of the pressed powder, or the green density, is reached. Although greatly reduced, interlocking space still exists extensively in the green compact.
Much of this space is still an interconnected network of pores, mainly open pores. The density of the compact relative to the applied pressure varies with different processing factors. A typical relationship between pressure and compact density is shown in figure 329. Note how the rate of density increase drops off between the initial repacking stage and the second plastic deformation stage.
Ideally the density increase would occur uniformly throughout the compact. However, due mainly to friction and part geometry, variations in density can be a significant problem in powder manufacture. These problems increase with part complexity. Lubrication can help mitigate friction, providing a more even flow during compaction. Over lubricating should be avoided. Another method to create a more uniform density in the pressed compact is to use additional punches with separate movements. Multiple action pressing of powders is common industrial practice with more complex parts.
The principle of the design of a powder pressing operation using one, two, or multiple actions, is based on the way that powders compress. Less pressure within the powder material will result in less compaction and lower density in that area. Pressure within the powder decreases with distance from the punch surface. For a single punch that would mean through the thickness of the part.
When manufacturing a thin part from a powder, (high diameter to thickness ratio), this may not present a problem. With thicker parts, significant density variations might occur relative to the distance from the punch. To mitigate this type of problem of density-pressure variation within a compacted powder, two opposing punches are usually employed.
Powder sintering involves raising the temperature of the green compact, (pressed powder part), to a certain level and keeping it at that temperature for a certain amount of time. The sintering temperature is usually between 70% and 90% of the melting point of the powder metal. This will cause bonding mechanisms to occur between powder particles pressed together in the compact. Bonding within the green compact is weak and this pressed unsintered part usually has just enough structural integrity to be handled. Bonding that occurs during sintering greatly strengthens the part.
During sintering, the individual particle structures disappear and the material forms as a mass. Conventional sintering will not eliminate all porosity in the part, however it does reduce the porosity further. In addition to being reduced in volume, sintering may also isolate areas of the interconnected open porosity in the green compact. These isolated areas become closed porosity, since they are cut off from the outside environment. Sintering is characteristic in the burning off of additives in the powder that were necessary for earlier processing stages. Elimination of constituents no longer needed such as lubricants, binders and deflocculates, is essential to maintain the purity of the material of the final product. In addition to increasing the strength and density of the part's material, sintering also increases ductility, thermal conductivity and electrical conductivity. Shrinkage will occur during sintering, but will be calculated for when manufacturing process factors are controlled.
Mechanisms that cause bonding during sintering are varied and complex. The main mechanism by which bonding occurs is considered to be diffusion, mechanisms will vary based on manufacturing process factors and powder characteristics. Some other mechanisms that may occur along with diffusion are plastic flow, recrystallization, grain growth, liquid phase material transport and vapor phase material transport. Physical characteristics of different types of bonding may be different. Particle bonding by two different mechanisms is illustrated below. The diffusion bonding shrinks the distance between particles, reducing space. The phase material transport adds material, while keeping the particles the same distance apart.
Bonding mechanisms during sintering are complicated and different, however the main driving force that enacts this particle bonding is considered to be a reduction of energy due to a reduced surface area. Powders with a greater surface area will have a higher driving force towards bonding and a lowering of this potential energy.
Alloying of different metal powders also occurs during sintering. The sintering temperature must always be lower than the melting temperature of at least one of the powder constituents. In some cases, the sintering temperature is above the melting point of one of the materials but below the melting point of the other. This is called liquid phase sintering. Liquid phase sintering can eliminate porosity and produce parts with excellent material properties.
Primary variables defining a powder sintering operation are time, temperature and furnace atmosphere. Sintering temperature is typically .7 to .9 of the powder's melting point. Sintering time is dependent on manufacturing process factors and material. Tungsten, for example, is sintered for a relatively long time. Standard industrial powder sintering times for different processes and materials vary from 8 minutes to 10 hours.
A controlled atmosphere is critical during powder sintering. The purpose of the atmosphere in sintering is to control carburization and decarburization, prevent oxidation and remove existing oxides, prevent unwanted chemical reactions and assist in the burning off of additives. Common atmospheres used for industrial powder processes are carbon monoxide, disassociated ammonia, hydrogen, partially combusted natural gas and inert gases such as argon or helium. Sometimes parts are also sintered in a vacuum. Vacuum sintering is mainly applicable to refractory metals and stainless steel.
Sintering of a green compact occurs in three stages. First, the powder compact is subject to preheating. Preheating will raise the part to a relatively low temperature, providing the burning off of additives. Preheating will also start to strengthen bonds within the part, increasing its integrity for the next stage. In the second stage the temperature is raised to the sintering temperature and maintained for a specific duration necessary for the desired amount of bonding to occur. Temperature is lowered as the part is allowed to cool during the third stage. Keeping the work in the controlled furnace atmosphere during cool down is critical in preventing unwanted chemical reactions between the part and the environment.
In industrial powder manufacture their are two types of furnaces, batch and continuous. In a batch furnace low quantities of parts are placed in the furnace, undergo the entire sintering process and are removed. Continuous furnaces provide flow through production and have three zones for the three stages of the manufacturing process, (preheat, sinter, and cool down). A moving belt carries a continuous supply of parts through the chambers. Heat doors can rapidly open and close to allow parts through, while keeping heat in. The belt travels at the exact speed to give parts the correct amount of time in each chamber. Consistent products and high productivity rates make continuous furnaces the most common choice for powder sintering. While batch operated furnaces have a lower productivity rate and are less often used, they do provide more control of the atmosphere and hence part purity. Vacuum atmospheres can generally only be provided by batch furnaces.
Porosity is a characteristic trait of powder processed materials. In some cases the goal is to mitigate or eliminate porosity. In other cases a certain level of porosity is desired. As discussed, porosity exists within the green compact. Amount of porosity in the green compact can be controlled to some extent by the level of pressure used to press the compact. If the compact is not fully pressed, more porosity will occur than with complete compaction. In fact, in loose sintering the powder is not pressed at all, achieving very high porosity for special components such as metal filters.
Measurement of porosity in a metal is usually quantified as the percentage of empty space in the material. Less than 10% is low porosity, 10%-20% is medium porosity and over 25% is considered a highly porous material. Porosity within the pressed green compact is mostly interconnected porosity, where the networks of pores are open to the outside environment. During sintering the volume of the porosity is reduced and many of the voids are isolated from the main pore networks and the outside environment. When pores become isolated within the material they are no longer considered open porosity, but closed porosity.
Impregnation is the filling of the pores in a metal with a fluid. A common application of this is in the production of self lubricating components such as bearings and gears. In these cases, the powder processed part is usually soaked in hot oil. Parts are typically 10%-30% oil impregnated by volume. Sometimes a part will be impregnated with polymer resin to prevent other substances from entering the pores or to assist with further processing.
Infiltration is the filling of a metal's pores with another metal of lower melting point than the base material. The infiltration metal is heated to a temperature above its melting point but below that of the porous metal part. Liquid metal is allowed to enter into the porous network and solidifies, filling the pores with solid metal. Infiltration can produce parts with special mechanical properties. Iron infiltrated with copper is a common example of this process in manufacturing industry.
As mentioned, pores may become isolated during powder processing. The amount of interconnected, open, (not isolated), pores is a critical factor for impregnation and infiltration. Material can not enter pores cut off from the outside environment. Amount of open porosity can be measured by the amount of fluid necessary to saturate the part.
With powder metallurgy, as with most other major manufacturing processes, there is often a need for further processing of the product. Porosity of parts manufactured by powder methods is a special factor in secondary, or finishing, operations performed on such parts.
The combination of powder metallurgy and forging is able to produce extremely high quality parts. A part is powder manufactured with about 15%-20% porosity, and then hot forged. Typically the forging is flashless. Hot forging eliminates porosity, increasing the density of the part. Hot forging of the powder processed part also creates a uniform wrought grain structure. Secondary processing of a powder manufactured part by forging greatly enhances the mechanical properties of the part. Since the powder forming produces the part to near net shape, the forging is often performed in one step. Other metal forming processes such as rolling and extrusion can also be employed as secondary operations on already pressed and sintered parts. These processes may also be performed cold or hot.
Machining of parts produced by powder metallurgy is common in industrial manufacturing practice. Machining is not often used for bulk removal, but for fine detail. Certain particular part features, such as side holes, cannot be produced by powder processing. Features not created during the pressing and sintering of the part can be produced latter by machining. A common problem with the machining of powder processed parts is the unwanted impregnation of the part's porous structure by coolant and lubricating fluids used during machining. Techniques such as machining dry and infiltration, (or impregnation), of the work with other materials are employed to solve this problem.
Sizing and coining are common finishing operations. Sizing is sometimes used on parts manufactured by powder processes in order to form the part to its final dimensions. Sizing involves only a small, but accurate, geometric change in the work. While sizing can be used to increase geometric accuracy, coining can be employed to improve surface finish and add details to parts created by powder processing.
Heat treatment of powder processed products can be performed, provided the porosity of the work is calculated as a factor in the manufacturing process. Increased porosity will decrease the thermal conductivity of the metal part, causing it to heat and cool slower than otherwise.
Surface processes such as painting or electroplated are also used in the finishing of powder processed products. As with other secondary and finishing processes, the porosity of the work must be considered. Materials for surface coatings should not be absorbed into the porous structure of the work. Infiltration and impregnation of porous parts is commonly employed to allow for surface treatments.
Starting with Mannesmann Pulvermetallurgie, SMS group has been active in press technology and powder metallurgy since the 1950s. Based on our experience, we know what you want from a powder press: cost-efficient production of complex sintered parts in consistently high quality. These parts go above all to the automotive as well electrical and general mechanical engineering industries. There is even more potential because new materials are constantly being developed and demand for complex, near-net-shape parts is growing. Both factors open up new, pioneering opportunities for powder press technology.
Ideal for precise, high-speed operation, our hydraulic CNC powder presses come in compact, four-column design. Crucial here is our patented controlled punch adapter (CPA). Using up to 12 axes, these machines produce even complex sintered parts very flexibly. You can rely on zero cracks or micro cracks.
Our hybrid press range features outstanding drive technology including a mechanical-hydraulic drive system for the upper ram. That gives you the advantages of a high-speed mechanical system efficiently combined with a top-precision hydraulic system.
Equipped with up to 12 axes, this tool offers you extreme flexibility for highly complex sintered parts. Thats because each punch level interacts fully automatically and is precisely controlled by the CNC system.
First, the punches shape the powder into the desired geometry. What makes all the difference here is perfect control that also takes account of punch interaction. No compacting force is applied yet. This stage is vital for the uniform density of the finished part. Next up is the coordinated press compacting process. As a result of the telescopic arrangement of the cylinders, each CPA axis is guided with pinpoint accuracy and can transmit high compacting forces. The hydraulic CNC axes ensure the uniform force of all punches. Furthermore, they compensate for punch expansion, particularly during the relief phase. So you get parts completely free of micro cracks.
An automated part calculation system is also implemented in the HMI which gives the operator a first set-up position. These ram positions can be simulated and checked on the screen before uploading to the press. Based on the calculated positions and the speeds needed, a theoretically pre-calculated energy consumption per part will be shown.
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Pressed powder is the workhorse of the makeup world, with a wide range of uses. Its essential in every purse and makeup drawer. No matter where you might be or what kind of look you like, its the convenient little item thatll help keep your face looking perfect. There are hundreds of fantastic pressed powders out there, so we reviewed the best of the best for every skin type!
Pressed powder is most commonly used to lock foundation into place and mattify the skin, which guarantees that makeup will look fabulous for long periods of time. Some pressed powders can even replace foundation altogether!
Some of the features you should look for in a pressed powder are universal while others depend on your preferences and individual needs. We go through them in this section, so you can keep them in mind when reading our reviews.
From the sheerest dusting to the most pigmented foundation-replacement, pressed powders offer a wide range of coverages. The coverage level thats right for you might not be whats best for someone else. If youre not sure whats right for you, read our detailed explanation of coverage levels. Then, in each review, well let you know the exact level of coverage you can expect out of each pressed powder.
A large shade range is important to inclusivity. People of color often struggle to find makeup because so many brands dont offer enough shades. With pressed powder, the more coverage it provides, the larger its shade range should be; with light coverage, one product can often suit multiple skin tones. Well let you know how many shades are available for each powder we review and also discuss how inclusive the shade range is in practice.
When selecting a pressed powder, you should pay attention to its finish (i.e. how reflective it is). Most powders are quite matte but others are downright radiant! Skin type and personal taste both impact which finishes will be best for you, which is why weve put together a comprehensive guide to finish types. In each review, well let you know what finish each powder has.
Some powders have a flashback effect when theyre photographed with a flash, so the face ends up looking ghostly in photos. Thats why we made sure that the powders on our list look good in photos (and in real life!).
Most people dont enjoy feeling their makeup weigh down their skin. Thats why we prioritized selecting finely-milled powders that dont sit on top of the skin. Their particles are small so theyre largely unfelt once applied, and they also look very natural. We dont discuss this aspect in much detail in our reviews since most of the powders we selected measure up to this requirement.
A basic, mattifying powder shouldnt be too expensive, but sometimes were willing to pay more for added features. Most of the powders we review cost around $10-$15, but when the price deviates from that, we discuss the value of each powder in more detail. To determine value, we take into account factors like product quantity and unique added features.
We can always rely on LOreal to make decent products, but even by their standards, this pressed powder is impressive. It gives us everything we want out of a pressed powder at a reasonable price. It wins our top spot easily because its so versatile. We can recommend it to nearly every person out there, no matter their style or skin type.
The finish is demi-matte, so it lightly mattifies the skin without making it look dry or cakey. If you have oily skin, itll look velvety-smooth and natural. If you prefer more intense oil-control then you can get the Maybelline Fit Me Matte + Poreless Pressed Powder, instead.
Those with dry skin can use it sparingly over a creamy base layer of foundation and it will set it down and reduce some of the shine. Because of its medium coverage level, you can play around with it quite a bit. Itll look sheer if you apply it with a fluffy brush, but if you use a sponge or flat brush itll have more coverage.
The shade range is not only fantastically large, but its also very well organized! LOreal has this great system of classifying their shades by undertones (W for warm, N for neutral, and C for cool), so finding a shade match is really easy. You can use this table to help guide you.
Lastly, we appreciate the super-durable and protective packaging. This powder even has a bottom compartment with a mirror and a sponge, which is nice, although we generally prefer the mirrors to be part of the top compact, which makes touching up on-the-go easier.
If you want to treat yourself, this is the most luxurious pressed powder to buy. Its expensive, but youll feel like royalty when its time to use it. It probably wont require touch-ups throughout the day, but youll still want an excuse to pull it out and show off the gorgeous rose gold packaging.
As far as performance, the most stunning thing about this powder is its filter-like effect. It helps camouflage texture issues and even works nicely under the much more wrinkle and dryness-prone under-eye area. This powder is incredibly finely-milled, so its very smooth and easy to pick up with a brush. Once applied to the skin, its weightless and natural-looking.
This effect makes it similar to the LOreal True Match Powder, but with a more natural finish thats better for dry and normal skin. It doesnt make the skin look matte, but it still absorbs oils, so its even a nice choice for those with combination or oily skin who prefer a glowy look.
This powder comes in 4 neutral shades, but because it has a lighter coverage level, a single shade works well across multiple skin tones. Often, small shade ranges only cover the lighter skin tones, but these 4 shades manage to be relatively inclusive, with the two deeper shades working well for dark and very dark skin.
Since this powder is so expensive, you may choose to use only under the eye area or for special events. This allows it to last for a longer time. If youre usually a luxury shopper and have dry skin, its the best pressed powder to buy, but if youre on a budget, the slightly more luminescent COVERGIRL Advanced Radiance Pressed Powder is another option.
This great powder is part of Maybellines Fit Me line, which also includes a massively popular liquid foundation. Like the LOreal True Match Powder, its a fantastic do-it-all, but it works even better for those with very oily skin.
It mattifies the skin instantly, but then it keeps absorbing oils throughout the day to keep the skin shine-free. Those with combination skin can use it specifically on the areas where they get shiny. In addition to mattifying, it also has a gorgeous blurring effect that helps to minimize the appearance of large pores. The mineral-based formula perfects the texture of the skin and makes it look smooth and matte, which is especially nice in photos.
Another nice feature is the versatility of the coverage level. Its perfect when applied lightly as a setting powder, but you can also use it as a foundation-replacement on light makeup days. If you apply it with a flat-topped brush or a sponge it will give decent stand-alone coverage.
The shade range is good, but shopping for your shade online might be difficult. Maybelline doesnt offer great swatches and the shade names dont hint at important details like undertones. Still, its a solidly affordable drugstore option, and while it comes with a bit less product than the LOreal powder, its usually also a few dollars cheaper.
If you like your pressed powder to do all of the heavy lifting, this is a great product to pick up! Made by bareMinerals, the formula is similar to the brands iconic loose powder foundation, but in a convenient pressed format.
This means that its meant to be used instead of foundation, to even out the skin tone and camouflage imperfections. It has a buildable formula that can go from medium to full coverage. bareMinerals did a great job of offering a wide shade range, which is important considering the high coverage level. These swatches will help you find your shade match, although sadly, not all colors are always in stock.
Powder foundations, in general, are better for those with oily or combination skin. Thats even more true for this powder, which has a matte finish. It does a wonderful job of absorbing oils throughout the day and keeping the skin from looking greasy. If you have dry skin it might emphasize dry patches, so youll want to try the PR Pressed Mineral Makeup instead.
It comes in a compact that includes a sponge and mirror for touch-ups on-the-go. This portability almost goes to waste, since it has excellent longevity and many shoppers find that they dont need to touch it up at all throughout the day.
Despite the effects and high coverage, this powder is famously lightweight on the skin. If you dont like the feel of heavy foundations but still want your skin to look perfected, its a fantastic alternative.
Rimmels Stay Matte powder is an oldie but a goodie. It may not look like much, but it performs impeccably. Best part of all? It costs very little for a ton of product. And not only is it the least expensive option on our list, but a single compact contains 0.49 oz of product, which is about 0.2 oz more than most other pressed powders.
As you can guess from the name, this powder is designed for oil-control, much like the Maybelline Fit Me Matte + Poreless Pressed Powder. The coverage level is lighter, so its an even better setting powder for light looks.
While you can build up its coverage to medium, it might look a little cakey and may have slight flashback in photos. Misting it with some sort of hydrating or setting spray is usually enough to take away the cakiness.
Its available in 8 shades, which we think is acceptable for light coverage. The range goes from the ultra-light Transparent all the way up to Pecan, with shades like Natural, Deep Beige, and Toffee in between.
Unfortunately, this powder is only suitable for oily skin, and even then you may want to avoid using it under the eyes where the skin is usually drier. If youre a budget shopper with dry skin we recommend the COVERGIRL Advanced Radiance Pressed Powder, instead.
The one flaw is that the packaging feels cheap, with a screw-top lid thats less convenient than a typical compact. Considering how little this powder costs and how nice it looks on oily skin, were perfectly happy to overlook this flaw.
From Revlon, this is a simple yet lovely pressed powder for setting foundation across various skin types. It has that perfect demi-matte finish that mattifies lightly without making the skin look parched, and the coverage is ideal for locking foundation in place without adding too much color.
Our favorite thing about this pressed powder is the color selection. Sure, 14 shades is not impressive, but the color selection itself is unique. This powder is primarily intended for setting creams and liquids, so while it does come in typical skin tone shades like Light or Mocha, it also comes in no-coverage translucent shades.
These shades include Translucent, which works across all lighter skin tones without altering the shade of the foundation, and the strongly-yellow Banana, which has a tint thats perfect for those with strong warm undertones and deeper skin tones. It can even correct the undertone of an overly-neutral foundation!
When purchasing your shade, be a little careful. Revlon provides an excellent shade chart in the photo gallery for this powder, but sometimes the listing and shades dont quite align. Cross-reference the name of the product in your cart with the main chart to confirm that its the shade you want.
Like other drugstore powders, it also comes with a mirror in a bottom compartment. Theres also an included applicator sponge which amps up the coverage of the powder to medium, which is nice for touch-ups.
The powder is very finely-milled, so it goes on the skin smoothly and is quite undetectable. It also feels very light and pleasant. If you want something even more matte but with the same light coverage, the Rimmel Stay Matte Powder is a great choice.
This vegan, mineral-based pressed powder is highly unusual: its a powder foundation made specifically to suit dry skin. There arent many of those, so we absolutely had to share it with you, despite its high price tag.
The coverage is phenomenal and it can absolutely replace your foundation, although you may still want to use a concealer for severe discoloration or blemishes. It comes in 22 shades, which is enough for most shoppers. We also love that when you click on a shade on Amazon, you can scroll through the pictures to see women wearing each shade, which will help you find your match.
The reason the formula works so well for dry skin is its satin finish, which comes from a blend of finely-milled reflective pigments and moisturizers like shea butter. These creamy ingredients have a natural-looking sheen and they help to moisturize the skin.
This formula is also one of the few talc-free options on our list. Talc is great for mattifying the skin, but in recent years its become a little controversial as an inhalation risk (more so for workers or children than to the average makeup wearer).
When first applied, it can look a little powdery, but it quickly adapts with the heat of the face to have a glowy, skin-like finish. You can even dust it on as a setting powder, in which case it wont look powdery at all but will increase your cream foundations coverage.
CoverGirl has a huge line of powders, and theyre each incredible. Our favorite of the bunch, however, is the Age-Defying Pressed Powder. It offers something that most pressed powders dont: a stunning, luminescent finish that looks great on dry or maturing skin.
All of the powders weve reviewed so far are very finely-milled, but this one takes it up a notch. It glides smoothly even over very dry skin and never emphasizes texture. The reflective quality of it doesnt look like a shine or a shimmer because those reflective pigments are ground down so finely. It just looks healthy, dewy, and totally skin-like!
This performance reminds us of the Charlotte Tilbury Flawless Finish Setting Powder, but its not nearly as expensive so you wont feel wasteful if you use it all over your face as a setting powder. Radiant Finish is also a touch dewier and more reflective. Even if you have oily or combination skin, you might still like it for setting concealer under the eyes. It can even work as a highlighter if you buy a shade thats slightly lighter than your skin tone.
All-in-all, theres a ton to love about this powder, but it sadly comes in an inexcusably small shade range. Normally, one single flaw wont be enough to push such a great powder so low on our list, but this is the exception. Even the darkest shade in the range is going to be too light for a huge range of people. If CoverGirl were to introduce it in a few more shades, it could easily become one of the top pressed powders on the market.
Its critically important to reapply sunscreen after 2 hours of continuous sun exposure. Sadly, there arent many convenient ways of doing it when youre already wearing a full face of makeup! A pressed powder with SPF presents an excellent solution to the problem. Its great for touch-ups, although on its own, its hard to use enough for sufficient protection.
It comes in three neutral shades: Translucent is the lightest (and isnt technically translucent), Creamy Natural is great for light to medium skin tones, and Beige will work for those with tan or slightly dark skin. We do wish there were a few more shades for those with darker skin.
This powder has a natural finish, which allows it to work for all skin types. Its decent as a setting powder, but you can also keep it in your purse and reapply over other setting powders. Its free of fragrances and other potential irritants, so its great for those with sensitive skin, and even clean beauty fans will like it since the formula is talc-free.
One major drawback to this powder is that it has a very intense white cast and it can look chalky on the skin. This is because the sunscreen minerals in it reflect light. Unfortunately, we dont know of a mineral pressed powder with such a high SPF without any white cast.
We wouldnt recommend using it as a pressed powder for evening events when youre more likely to be photographed with a flash. Fortunately, those are also the times when you wont need a powder with sun protection!
Finally, a quick word about the packaging: to our eye, its not particularly stylish, and even looks a little cheap. It comes with a brush in the bottom compartment, which can be nice when its time to reapply.
As a rule, were not fans of HD pressed powders. They are a category of translucent (i.e. non-pigmented) powders designed specifically for HD cameras. They are meant to have zero color, and their main benefit is the ability to diffuse skin texture, though they also mattify and set foundation. In practice, HD powders often look chalky on the skin and theyre very prone to flashback.
Out of all of the HD pressed powders out there, this one from e.l.f. is our favorite. It measures up to the skin-blurring claim, giving the skin a smooth, airbrushed appearance. It looks gorgeous in pictures, and as long as you use it sparingly (as e.l.f. recommends) it wont flashback even in flash photography.
The powder looks white in the compact, but its actually translucent. When applied lightly, it wont alter your skin tone or foundation at all, even if you have medium-dark skin. Its a great choice for those who struggle to match their undertone with pressed powders!
Unfortunately, it can appear chalky on very dark skin, especially if you use more than the minimum. If you like the idea of it but have darker skin, the Revlon ColorStay Pressed Powder in Banana would be a better choice even if its not an HD powder.
It has a demi-matte finish that can work well for all skin types, though on those with dry skin, adding too many layers will likely look cakey. The powder has great longevity, which we certainly appreciate.
Its important to learn about the factors that influence how a pressed powder will actually look on your skin. This way, you can select the one or two or three thatll find a home in your makeup bag!
Translucent powders are meant to have almost no coverage. They look white or cream-colored and are mainly used as setting powders. The e.l.f. Perfect Finish HD Powder is a great example of a true translucent powder.
Some translucent pressed powders are tinted so they blend better into the skin. An example of that would be the Revlon ColorStay Pressed Powder in Banana which has a yellow tint for warm undertones. It can still alter the finish of the skin, but it wont hide anything.
Sometimes brands complicate things by naming one of their lighter shades translucent despite the powder still having light or even medium coverage. This can be confusing, so always look for a coverage level description instead of just relying on the shade name.
Light coverage pressed powders have a touch more pigmentation than translucent powders. They work very well as setting powders, and they can also add a tint to a foundation if the color is a little off.
They do increase the coverage of any foundation applied below them, but its very subtle. If theyre applied over bare skin, the skin will look slightly more even but discoloration or blemishes wont be hidden at all.
As you can probably guess, medium coverage powders offer a little more coverage than light ones. This makes them very versatile, which is why medium coverage powders like the LOreal True Match Powder and the Maybelline Fit Me Matte + Poreless Pressed Powder show up near the top of our list.
When theyre used to set a foundation, they increase its coverage by a level. When used alone they perfect the appearance of the skin, hide diffused discoloration, and reduce the visibility of blemishes. They can easily replace a light coverage foundation.
Influencers on Instagram and YouTube often use a high-coverage powder to set their foundation, because it gives an incredibly high level of coverage. It can look cakey in real life, but on camera, its totally flawless.
Some light coverage pressed powders, like the Charlotte Tilbury Flawless Finish Setting Powder can be built up to medium with more layers. Some medium coverage powders like the bareMinerals Powder Foundation can be built up to full coverage with added layers.
The term finish refers to how flat or reflective a pressed powder is. There are four main finish types, but how they register on your skin also depends on your skin type, so check out our section on skin types as well.
Matte finish is the most common, and it refers to powders that dont reflect any light and look dry as a result. Matte powders do a good job of absorbing oils and keeping the skin from looking greasy, tough they make dry skin look even drier.
Powders with a demi-matte finish are very popular these days. They are only slightly matte, giving the skin a finish often described as velvety. They still eliminate excess sheen and oiliness, but without leaving the skin looking dry.
When those with very oily skin use a demi-matte powder (or when its applied over a dewy foundation), the result looks totally natural. If used by those with normal skin, the skin looks a little more matte, but without the intense flatness of a matte powder. Those with dry skin can still use demi-matte powders, but its important to apply conservatively.
Powders with a natural finish are quite special since they work well for all skin types. Theyre neither shiny nor mattethey simply look like healthy, normal skin. They still absorb excess oil from the skin, but the minerals in them are more reflective.
Those with oily skin can use them for a dewy finish while those with normal and dry skin can use them for a natural finish. This type of powder wont alter the finish of any foundation applied below it, but itll still set it. That means that over a matte foundation, the skin will still look matte, while over a dewy foundation the skin will look dewy.
Even more unusual are powders with a luminescent, radiant, or dewy finish. Were not talking about shimmery highlighters, but about pressed powders that give the skin the same finish as your favorite dewy foundation.
Unfortunately, pressed powders with a luminescent finish are very rare since many shoppers with dry skin often skip powder altogether. This is why the only luminescent pressed powder we were able to recommend is the COVERGIRL Advanced Radiance Pressed Powder.
Your personal skin chemistry has a huge influence on how makeup will look on your skin. Just because a specific powder makes your friends skin look soft and smooth it doesnt mean that itll do the same for you. By knowing your skin type you can choose the best pressed powder for your needs.
Oily skin produces a lot of sebum throughout the day. If you have oily skin, chances are your skin gets shiny very easily, especially along the forehead, nose, and chin, and that you have larger pores.
In that case, you will likely want a pressed powder that will help keep those oils at bay and leave your skin matte, like the Maybelline Fit Me Matte + Poreless Pressed Powder. A demi-matte powder like the LOreal True Match Powder will also help while allowing your skin to retain a small amount of sheen.
Finally, if youre a fan of a more dewy look where the skin still looks a little moist, a powder with a natural-finish like the Charlotte Tilbury Flawless Finish Setting Powder will interact with your skins natural oils in such a way that youll look dewy but not greasy.
Dry skin produces very little sebum throughout the day. Its prone to dehydration so it can feel tight, look a little dull, or get flakey. Powders often emphasize dryness and texture issues, so if you have dry skin you may struggle to find a powder that will work for you.
The best powders for dry skin are the natural-finish Charlotte Tilbury Flawless Finish Setting Powder and the more dewy COVERGIRL Advanced Radiance Pressed Powder. They are both intensely finely-milled so they appear smooth even over dry areas.
Combination skin sits on the spectrum between dry and oily, with certain parts of the skin producing more oil than others. Normal skin is often used interchangeably with combination skin, although it usually has a balanced level of sebum production all over the face.
If you want to have just one pressed powder that you can use all over the face, its best to choose one with a natural finish. Itll still absorb any excess oils from the oily parts of your face, but it wont make your skin look dry anywhere else.
It may not take out the trash or balance your budget, but theres a lot that pressed powder can do! It can set your foundation to guarantee a flawless look all day long, or it can live in your purse and help you blot away shine in the middle of the day. When you understand all of the nuances of finish and coverage and how they relate to your own skin type and style, you can easily find the right pressed powder for you!
Maya is a makeup artist, writer, and total geek about all things beauty. She loves researching the latest techniques and reading about new skincare ingredients. She ignores marketing buzzwords and instead dives deep into formulations and performance, to always recommend the most effective cosmetics on the market.
With the development of world automobile industry and transportation industry, a large number of waste tires are discarded every year, which leads to serious environment pollution. But on the other hand, waste tyre is a potential resource which can bring profits for people if disposed properly. Based on this idea, Beston Machinery has developed the rubber powder production line, which aims at disposing waste tyres and waste rubber in a green and profitable way.
The entire rubber powder production machine can effectively crush the whole tyres into small rubber granules with the size of 30 to 200 mesh. And the rubber powder from waste tyres can be reprocessed to widely used in many fields.
1. Through desulfurization process, the rubber powder will be reclaimed as rubber production sheet material, which can be used in the manufacture of machine pads, roadbed mat, cushion, various washers, fenderboard, sound-absorbing materials, etc.
2. The rubber granules can be used to make color elastic floor tile laid in the sports ground to guarantee safety of elderly and kids. It has these advantages: prevent slippery, achieve shock absorption, wear-resistant, sound insulation, heat insulation, water resistant with none toxic and long service life.
The comprehensive tire shredder is mainly used to shred the whole tyre. (The size of the tyre is smaller than 1200 mm. Besides, tyre bead has been removed and the steel in the tyre bead has been also removed) into rubber blocks of 50 mm. It usuallycan be used as pre-treatment equipment of tyre pyrolysis plant. So it is quite important for the rubber powder production line.
Having been crushed into rubber blocks of 50mm by the shredder, the tyres are conveyed to the coarse crusher by the belt conveyor. The coarse tire crusher can crush the rubber blocks into small size of 2-15mm.
4. It is equipped with special grinding wheels, which can produce 30-200 mesh rubber powder. Please feel free to give your inquiry in the form below. We will reply in 24 hours. Product Model: Your Name(required): Your Email(required): Your Tel(required): Your Country: Your Company: Your Message(required):
With more than 550 units installed all over the world under proprietary design and know-how since 1960, the Desmet Ballestra plants are estimated to cover a significant part of the world's production of synthetic powder detergents.
The extensive experience and know-how in detergent plants operation also allows Desmet Ballestra to assist Clients in better defining their requirements in terms of production programs, product formulation and packaging, so contributing to the best success of new projects.
A permanent and qualified Research & Development staff is dedicated to improving the technology by optimizing the existing processes and developing new ones in the laboratories and pilot plants installed at our Milan headquarters.
Vlinge has developed a very compact profiling unit, primarily designed for installation in existing edgebanding lines. The concept performs 5 operations in one compact unit and has very small footprint of appr. 800 x 800 mm.
The plastic insert that connects the panels is placed during production using an inserter machine.Choose the high-speed inline inserter for high-volume production or the handheld inserter for smaller series.
Threespine is perfectly suited for fully automatic factory assembly using robots: a fast, easy and flexible assembly solution that also opens up possibilities to manufacture both factory assembled and flat pack/RTA furniture in the same production lines.
Before you choose a brand, find out how many shades they offer if you fall in the in between category. If yours is a hard skin tone to match, you may have to pick the brand with the closest match even if its not your favorite.
Sure, these will work for a few applications, but the more you use them, the more dirt, oil, grease and grime builds up. Every swipe across the powder and every swipe across your face with a heavily used applicator will just reapply all of that dirt and grime!
All pressed powder starts as a loose powder. By adding oils, waxes and other ingredients, makeup manufacturers are able to create the right consistency so that they can press them into the compact case.
Due to the added oils, a pressed powder is easier to use for touchups throughout the day since it wont fly around in its case. Many use it in place of a liquid foundation, which seems to work best on those with normal skin (the lucky ones with no oil problems!)
You can apply loose powder with a variety of brushes based on the amount of coverage you need. Those of you with excessively oily skin will probably do best with a loose powder, but having a pressed powder in your purse for touch-ups is definitely a great idea.
What we love about Laura Merciers formula is that its oil free yet it still has a creamy texture that glides right over your skin. In this, youll find Jojoba esters, white tea extract and rice lipids to provide you with more natural coverage. It also contains SPF 15, so you get a little extra protection from the sun when you wear this, too.
Above, weve featured Nude Beige, but check out all of the other shades they have: This is also an oil-free formula that will provide you with light to medium coverage. It also has a hint of pearl pigments in order to give you that flawless glow.
Here are the shades, Translucent being the one featured in our table above: In terms of quality, it does a great job at reducing the appearance of pores (as the name suggests) and seems to work extremely well with BB creams, CC creams and tinted moisturizers.
Foundation? Check. Concealer? Check. Now, all you need is some powder. Considered to be a staple in every makeup kit, pressed powders add the perfect finishing touch without feeling cakey or unnatural. Pressed powder is essential for locking everything in for long-wear while blurring any imperfections, says New York City-based makeup artist Jonet Williamson. Adding a sweep of pressed powder can also come in handy when dealing with shine, hiding pores and lines, and preventing any unwanted discoloration from peaking through.
While finding the right powder formula for your skin is crucial, Williamson says that your application also plays an important role in achieving that airbrushed look. I like to use [powders] lightly where needed, primarily in the T-zone where the face tends to get oily, she explains, noting that shell use different shades for different parts of the face. They can also be used to give added definition to the face by highlighting and contouring.
Feel like your glam is missing something? Odds are its because youre not using this Charlotte Tilbury powder. A favorite of celebrity MUAs and Byrdie editors alike, this super-luxe option is designed to take your skin up a notch with its skin-perfecting airbrush effect. The secret is in its soft-focus, light-diffusing formula, which blurs lines and imperfections while also illuminating the skin. This powder also contains a hydrating blend of rose wax and almond oil, making it suitable for dry skin types and those looking for a formula that doesnt feel caked on.
For less than $15, Morphes Filter Effect Finishing Powder delivers the same poreless, radiant finish as its competitors without the steep price tag. Its buildable formula can be customized to your coverage preferences, but you dont have to worry about it layering in a clumpy or cakey way. Instead, its mattifying, oil-absorbing, and texture-blurring formula freshens up the skin, locks in makeup, and creates a silky-smooth complexion thats selfie-ready. Its great for touch-ups throughout the day if you notice your skin needs it.
This drugstore powder takes shine very seriouslyso much so that it delivers up to 12 hours of coverage. Not only does it keep shine in check, but it also leaves the skin looking poreless and mattified. Plus, its long-lasting formula builds to your desired coverage and never makes you feel like youve caked on layers of powder. Worried that it wont play nice with acne-prone skin? It's also oil-free and non-comedogenic, meaning that it wont clog pores or cause breakouts.
If you have dry skin, odds are youve been let down by a pressed powder in the past. While a sweep of powder can be great for absorbing shine and keeping makeup in place, it can also cling to dry patches and lines if the formula isnt hydrating enough. To combat unwanted caking and piling, this Bobbi Brown powder contains vitamin E to ensure that the skin stays moisturized.
When it comes to finding the best pressed powder for oily skin, Williamson says translucent formulas are ideal for those who are looking to soak up extra shine while also enhancing your glam. This Clinque powder fits the bill perfectly. Its sheer finish doesnt disrupt the skins natural texture by bunching and clinginginstead, it works with it to deliver a refreshed, refined look thats free of shine and imperfections. The formula is also oil- and fragrance-free, so those who are prone to breakouts and sensitivity can enjoy it as well. Not looking for a translucent finish? This pressed powder is also available in nine additional shades.
Those with acne-prone skin know that not every ingredient agrees with their pores. According to Williamson, a good way to avoid any unwanted breakouts is by opting for mineral pressed powders. These tend to be oil-free and non-comedogenic, as well as contain more natural ingredients, she explains. Williamson recommends this MAC powder for anyone who is breakout-conscious. Its formulated with low-level pearlized pigments and vitamin E to blur imperfections and give skin a dimensional and radiant look. Its coverage falls on the lighter side, which might not be a good fit for oily skin types, but it also comes in 14 shades and can act as both a bronzer and a setting powder.
This pressed powder ranks highly among Byrdies editors because of its skin-perfecting formula. Silica and micronized pigments come together to reduce shine as well as smooth the appearance of fine lines, pores, and wrinkles. But dont let its intense mattifying abilities worry youits also hydrating and doesnt cake or cling around dry spots. For this reason, we love it for those with combination skin who want a product that addresses both oiliness and dryness.
Another recommendation from Williamson, this popular powder is formulated without any ingredients that are known to irritate sensitive skin. Designed to even the complexion, absorb excess oil, and fade the appearance of fine lines and pores, the formula has a velvety-smooth feel that moves with your skin in order to prevent creasing and caking. Its also incredibly lightweight and hydrating, thanks to its hyaluronic acid-fortified formula.
This IMAN Cosmetics powder accounts for every undertone with its shade range, ensuring that everyone finds their perfect match.Described as having a light-as-air texture, this powder leaves skin with a natural-looking finish while also controlling oil and shine. But rest assured, it wont settle into fine lines or cause creasing thanks to its silky and hydrating formula, which Williamson says is always a good sign when it comes to powders. The powders you use should be rich and buttery in texture so that they melt into the skin versus sitting on it, she says.
When selecting powders for deeper skin tones, getting the correct undertone is super important, Williamson recommends. I'd veer away from pressed powders that are too orangey or reddish and instead, look for powders that have golden or neutral undertones to balance out the warmth that is already present in the skin.
While Make Up For Evers Matte Velvet Blurring Powder is technically a foundation, its available in 30 diverse shades that cater to a variety of undertones. It also comes recommended by Williamson and Byrdie senior editor Hallie Gould for its velvety matte finish and lightweight, comfortable feel. It also doesn't skimp on performance, promising to stay put for up to 12 hours, erase imperfections, and soak up shine with its blurring technology.
This powder helps put the finishing touches on your complexion by imparting a luminous glow, thanks in large part to its skin-healthy blend of vitamins A and C. But a glow isnt its only wow factorthis multitasking product also smooths the complexion and adds a visible lift, which makes it particularly great for those with mature skin. Its also an excellent powder for setting foundation, as it helps extend its wear and prevent excess shine from peeking through.
This may be more of a loose powder than a pressed powder, but its renowned for its long-wear formula that lasts all day long. Not only does it stay put through humidity, but it also delivers impressive full coverage without leaving any traces of creasing. It's available in four shades and uses the brands Shade ID technology to adjust to your skins undertones with color-matching pigments. Worried about dealing with flashback since its technically a loose powder? Plenty of reviewers have vouched that it's seamless to blend and that the formula is flash-friendly.
Whether you use this product as a finishing powder or by itself as your foundation, it will help turn up the watts on your complexion. Its versatile 2-in-1 formula is lightweight yet buildable, working with the skin to provide a natural-looking finish that's never cakey. Its also great for soaking up any excess oil and shine and significantly reducing the appearance of pores.
Acne scars are notorious for being difficult to cover with foundation alone, which is why you may need a full-coverage powder for backup. This Dermablend option doesn't just conceal acne scarsit also ensures that they stay camouflaged throughout the day. Its soft-feel formula can be built up to match the level of coverage needed and it's mattifying enough to tackle shine and blur pores, too. If youre using this powder to cover acne scars, youre probably just as worried about it causing future breakouts, right? Thankfully, its non-comedogenic and oil-free, so it wont clog pores or exacerbate any existing skin issues.
Product NameWholesale 5 Colors Pressed Compact Makeup Powder Custom LogoModel NumberMSF05029ZTypeCompact PowderFeature:1.Matte Powder: Many color for your choice, perfect for all skin tones and type.2.Long LastingPowder: Creating a natural and perfect cheek makeup.3.Controls Oil & Lightweight &Water ProofColor5 ColorsWeight100gSized75*20;75*77*22INGREDIENTS:IsododecanePolymethylphenylsiloxaneSilicaFilm formerTitanium dioxide Pentaerythritol tetraisostearateStyrene oxide isoprene copolymerFumed silicaSericiteIsooctyl PalmitateWhite ceresin BYellow beeswaxDimethicone Red 6Iron Oxide RedIron Oxide Yellow
MSmakeup-Private label cosmetics no minimum. MSmakeup is Original cosmeticsmanufacture & Wholesale makeup vendor. No MOQ (No minimum order quantity)for wholesale. 50 pcs for private label cosmetics.Cheap on line makeup Stores,amazing products. We are GMP and ISO22716 certificated manufacturealso offer OEM/ODM service, can customize new formula contarct manufacturing.
Q:1. How can you guarantee your productsquality?A: _ We are makeup manufacture with 10 years experience. And have the GMPC and ISO22716 certificates. _ All the formula can offer MSDS for each item. _ Professional customer service team 24 hours on-line.
1.Delivery time= process time+shipping time2.Sample /white label/no logo products) process time= 48-96 hoursholidays not includedafter payment3.Shipping time: Vip shipping : 3-7 Working Day Standard shipping:10-15 Days Shipping by sea:20-30 Working Days
Free SHS compaction was tested as a method for producing large compact plates more than 100 mm in size from powders of high-melting inorganic compounds based on titanium diboride. Materials science studies of the obtained plates were performed, and their physicochemical properties were investigated. The synthesized material was heat-resistant at temperatures to 1100C.
Rogachev, A.S. and Mukasyan, A.S., Gorenie dlya sinteza materialov: vvedenie v strukturnuyu makrokinetiku (Combustion for Materials Synthesis: Introduction to Structural Macrokinetics), Moscow: Fizmatlit, 2012.
Amosov, A.P., Poroshkovaya tekhnologiya samorasprostranyayushchegosya vysokotemperaturnogo sinteza materialov. Uchebnoe posobie dlya studentov vysshikh uchebnykh zavedenii, obuchayushchikhsya po napravleniyu Metallurgiya (Powder Technology of Self-Propagating High-Temperature Synthesis of Materials, A Textbook for Higher School, Specialty Metallurgy), Moscow, 2007.
Stolin, A.M., Bazhin, P.M., Konstantinov, A.S. et al. Production of Large Compact Plates from Ceramic Powder Materials by Free SHS Compaction. Dokl Chem 480, 136138 (2018). https://doi.org/10.1134/S0012500818060083
Die-pressed agglomerated alumina compacts, prepared as cylinders using single-ended nominally uniaxial compressive stresses, have been characterized by measuring their strength and density distributions. The strength of the alumina compacts, measured using the Brazilian configuration, increases up to an optimum compaction pressure; upon further increasing the compaction pressure, the strength of the green compacts decreases due to the formation of internal cracks. The density distributions in the alumina compacts have also been determined experimentally, using the coloured layer technique and also deduced indirectly from hardness measurements. The results obtained from these two experiments are shown to be in good agreement. The densest parts of the compacts, compressed uniaxially from the top planar surface adjacent to the compression source, are at the outer circumference at the top and the least dense parts are at the outer circumference at the bottom face. The density near the cylindrical surface of the compacts decreases with height from the top to the bottom of the compact. The density difference between the most dense and the least dense parts of the compacts increases with increasing aspect ratio; that is, the height-to-diameter ratio. The density distributions in the alumina compacts have also been estimated using a first-order predictive model. According to this model, the mean density variation along the height of the compact decreases linearly with height from the top to the bottom of the compact. These predictions are shown to be almost in accord with experiment.