Tungsten carbide (WC) is a compound composed of refractory metal tungsten and nonmetallic carbon. It has the characteristics of high density, high melting point, high strength, high hardness, high-temperature resistance, corrosion resistance, wear resistance, and good electrical and thermal conductivity, so it is the ideal cemented carbide tool material.

However, due to the problems of high brittleness and poor toughness of simple WC powder, it is often necessary to add an appropriate amount of binders such as cobalt (Co), nickel (Ni), chromium (Cr), molybdenum (Mo), titanium (Ti), copper (Cu) and other elements in making cemented carbide tools with high comprehensive performance. 

Specifically, cemented carbide with WC powder as the hard phase and Co as the bonding phase is more suitable for cutting tools. Because of its good thermal conductivity, it is conducive to the loss of cutting heat from the tip, reduces the temperature of the tip, and avoids the overheating and softening of the tip; Due to its high bending strength and impact toughness, it can effectively reduce the probability of edge breakage in cutting. Because of its excellent cutting resistance (far more than high-speed steel), it can grind out a sharp edge. 

Cemented carbide with WC powder as the hard phase and Ni as the bonding phase is more suitable for corrosion-resistant parts. Its corrosion resistance is stronger than that of tungsten cobalt carbide tools, so it is suitable for application in a variety of corrosive media environments. In addition, WC-Ni cemented carbide seals are also suitable for application in low temperature, high temperature, vacuum, and high pressure. 

Cemented carbide, composed of WC, TiC, and Co, has high hardness, good heat resistance, high compressive strength, good oxidation resistance, poor thermal conductivity, and other characteristics, suitable for processing steel. 

The physical properties of cemented carbide vary with the ratio of raw materials. If the carbide surface is sprayed with a layer or layers of carbide, carbide, and other refractory hard compounds, then the alloy will be further compatible with high wear resistance and high toughness, so it is more suitable for high-speed cutting. 

Tungsten Carbide WC Price

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The crystal structure of silicon nitride

Si3N4 has two crystal structures: α-Si3N4 is a granular crystal, and β-Si3N4 is a needle-shaped crystal. Both are three-dimensional spatial networks composed of [SN4] tetrahedra sharing vertices, and both belong to the hexagonal crystal system. Their difference lies in the arrangement order of the [SiN4] tetrahedral layers. The β phase is composed of almost completely symmetrical six [SN4] tetrahedrons composed of hexagonal ring layers superimposed in the c-axis direction; while the α phase is composed of two deformed and different non-hexagonal ring layers superimposed. The α phase can dissolve oxygen in the crystal structure, and its internal strain is larger than that of the β phase, so the free energy is higher than that of the β phase. From a thermodynamic point of view, the beta phase is more stable at higher temperatures. The α phase has low symmetry and is easy to form. At about 1500°C, the α phase undergoes a reconstructive transformation and transforms into the β phase. This transformation is irreversible, and the existence of certain process conditions and qualities is more conducive to the transformation of α phase to β phase. α-Si3N4 is formed when it is lower than 1350℃, and β-Si3N4 can be directly prepared at a temperature higher than 1500℃.

Basic Properties of Silicon Nitride

The molecular formula of silicon nitride is Si3N4, of which Si accounts for 60.06% and N accounts for 39.94%. There is a strong covalent bond between Si and N (in which the ionic bond only accounts for 30%), so Si3N4 has high hardness (Mohs hardness 9), high melting point and stable structure.

Chemical stability of silicon nitride

Si3N4 is a thermodynamically stable compound. Silicon nitride ceramics can be used up to 1400°C in an oxidizing atmosphere and up to 1850°C in a neutral or reducing atmosphere.

Silicon nitride is stable to most metal solutions, not corroded or wetted, such as Al, Sn, Pb, Bi, Ga, Zn, Cd, Au, Ag, etc. But for Cu solution, it is not corroded only in vacuum or inert atmosphere; Mg can weakly react with Si3N4; silicon solution can wet Si3N4 and erode it slightly; transition element solution can strongly wet Si3N4 and form silicide with Si And quickly decompose silicon nitride, while escaping N2. Si3N4 is very stable to alloy solutions such as brass, hard aluminum, nickel-silver, etc., and has good corrosion resistance to cast iron, medium carbon steel, etc., but is not resistant to corrosion of nickel-chromium alloys and stainless steel.

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In addition to reducing friction, lubricants reduce the amount of wear that occurs during operation, reduce operating temperatures, minimize corrosion of metal surfaces and help keep contaminants out of the system.

With the progress of modern industrial technology, more and more machinery or equipment mechanization, automation, and super-large. The emergence of new technology is accompanied by the improvement of product performance. Now general lubricating oil has been unable to meet the lubrication requirements of the equipment. In this case, solid lubricants with better performance came into being. 

There are many kinds of solid lubricants, such as graphite, molybdenum disulfide, fossil fluoride ink, tungsten disulfide, boron nitride, and so on. The most widely used is molybdenum disulfide, and the best performance is boron nitride and fossil fluoride ink. 

Molybdenum disulfide is a solid powder made of natural molybdenum refined powder after purification. It is the modern "king of advanced solid lubrication". It has the advantages of high-temperature resistance, radiation resistance, high vacuum resistance, corrosion resistance, and extreme pressure resistance, so it has been widely used as additives for grease, powder metallurgy, modified plastics, spraying, and other industries.

Molybdenum disulfide is used in almost all grease-using markets and almost all types of grease thickeners, including lithium complexes, aluminum complexes, and polyurea. It is also considered to be the optimal additive for complex titanium greases with their inherent high carrying capacity and even better performance. 

Typically, grease contains 1% to 2% MoS2, and the key parameters are surface roughness, load, and speed. For rougher metal surfaces, larger MoS2 particle sizes are ideal because large particles fill deep valleys and contribute to a smooth surface. At a given MoS2 concentration, small particles will provide better load-bearing capacity. Also, very small particles may cause some corrosion problems due to high acid values. In general, a particle size of about 6m is the most commonly used MoS2 particle size in grease. 

Molybdenum disulfide has become an indispensable and irreplaceable industrial additive at present. It has made a great contribution to the development of modern new technology, not only elevating the lubrication technology to a new stage but also creating favorable conditions for the development of pure dry film lubrication. 

Molybdenum Disulfide MoS2 Price

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Spherical quartz powder, also known as spherical silica powder, refers to an amorphous quartz powder material whose particles are spherical in shape and whose main component is silicon dioxide.

Spherical quartz powder is mainly used for copper clad laminates and epoxy molding compound fillers in large-scale integrated circuit packaging, and also has applications in high-tech fields such as aerospace, fine chemicals and daily cosmetics.

Reasons for spheroidization of quartz powder

1. The surface area of the ball is the smallest, the isotropy is good, the film is evenly stirred with the resin, the amount of resin added is small, and the fluidity is the best, the filling amount of the powder can reach the highest, and the mass ratio can reach 90.5%. The increase in the filling rate of silica micropowder.

The higher the filling rate of silicon micropowder, the smaller the thermal expansion coefficient of the plastic sealing compound, the lower the thermal conductivity, the closer to the thermal expansion coefficient of monocrystalline silicon, and the better the performance of the electronic components produced.

2. The molding compound made of spherical powder has the smallest stress concentration and the highest strength. When the stress concentration of the molding compound of the angular powder is 1, the stress of the spherical powder is only 0.6. Therefore, when the spherical powder molding compound encapsulates the integrated circuit chip, the yield High, and not easy to produce mechanical damage during transportation, installation, and use.

3. The friction coefficient of spherical powder is small, the wear on the mold is small, and the service life of the mold is long. Compared with the angular powder, the service life of the mold can be doubled. The price of the packaging mold of the plastic sealing compound is very high, and some need to be imported, which is also very important for the packaging factory to reduce the cost and improve the economic benefit.

4. Silicon micropowder itself has the function of strengthening epoxy resin, and spherical powder can enhance this function.

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Steel 

Steel is one of the most commonly used metal materials in the industry and was the first metal material to be used for 3D printing. Currently, 3D printing can process many different types of steel, such as austenitic, duplex, martensitic, precipitate hardened stainless steel, TRIP/TWIP steel, Martensitic aging steel, tool steel, and ODS steel. Among them, the most commonly used are 316L stainless steel, 304 austenitic stainless steel, 17-4Ph, and 15-5pH martensitic precipitation hardening stainless steel, 18Ni300 Martensitic aging steel, and H13 tool steel.

Titanium 

Titanium and titanium alloys are ideal materials for 3D printing. First, 3D printing uses a small amount of material in total compared to other processes, making it more cost-effective in many applications, such as aerospace, medical (orthopedic implants), luxury cars, racing, and professional sports equipment. In these areas, where the cost of many parts is high (small amounts are needed), using more expensive materials for lightweight, increased strength, and durability based on 3D printing becomes a better option. 

Titanium alloys are biocompatible and corrosion-resistant and can be used as inert biomaterials for human implants. Today, the titanium alloy most commonly used in the 3D printing of orthopedic implants is Ti6Al4V (Ti64). 

Aluminum alloy 

Aluminum alloy is also currently one of the major metal 3D printing materials and is expected to grow in usage. Because the aluminum alloy is light and has good mechanical properties, the price is low. However, the mainstream aluminum alloy on the market is based on casting process development, which is not so handy for 3D printing. Because when aluminum is sintered, an oxide layer forms around the powder particles and needs to be removed at extremely high temperatures, but aluminum itself has a low melting point. 

At present, there are several aluminum alloys based on 3D printing on the market.  To use aluminum for 3D printing on a large scale, there will need to be breakthroughs in the material formulation and printing technology. 

Nickel alloy

Nickel alloy is a high-temperature resistant alloy and is often used to make parts that require high-temperature resistance. It is widely used in energy production, oil, and natural gas fields. The main nickel alloys currently used for 3D printing are Inconel 625 and 718. 

Cobalt chromium alloy 

Currently, many people do not know that cobalt-based alloys can be used for 3D printing.  However, their applications in orthopedics, aerospace, power generation, and dentistry are significant. ASTM F75 CoCr is commonly used, which has good high-temperature performance, high strength, corrosion resistance, wear-resistance, and biocompatibility. 

Copper and copper alloys

Copper and copper alloys are widely used in industry because of their excellent electrical conductivity, thermal conductivity, and ductility. But copper's high reflectivity and thermal conductivity make it difficult to 3D-print. Fortunately, 3D printing technology has improved in recent years, and there are now several ways to 3D print copper. 

Refractory metal 

Refractory metals are very resistant to heat and wear, mainly niobium, molybdenum, tantalum, tungsten, and rhenium. They have some common characteristics, melting point over 2000℃, high hardness at room temperature, high density, etc. Due to their very high melting points, these materials are very challenging for 3D printing. Currently, they are mainly printed from these materials by binder injection 3D printing technology, and then sintered at high temperature to obtain the final part.

RBOSCHCO is a trusted global chemical material supplier & manufacturer with over 12-year-experience in providing super high-quality chemicals and nanomaterials including silicon powder, nitride powder, graphite powder, zinc sulfide, calcium nitride, 3D printing powder, etc.

The company export to many countries including the USA, Canada, Europe, UAE, South Africa, Tanzania, Kenya, Egypt, etc.

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Silicon powder: 

Silicon powder is a non-toxic, tasteless, non-pollution inorganic non-metallic material. The silicon content of silicon powder is more than 99%.

Because it has good temperature resistance, acid and alkali corrosion resistance, high thermal conductivity, high insulation, low expansion, stable chemical properties, hardness, and other excellent performance, it is widely used in chemical, electronics, integrated circuits, electrical appliances, plastics, coatings, advanced paint, rubber, and other fields. 

Metal silicon powder: 

Silicon metal powder is a powdery substance formed by grinding silicon metal.  Different metal silicon powder, the content of each element is also different, the common 441 metal silicon powder, 553 metal silicon powder, 97 metal silicon powder, and so on. 

The main component of silicon metal powder is crystalline silicon.  At first, it was blocky and the color was relatively stable.  After a series of crushing or grinding processes, it changes to a powder state.  In general, it's not active. 

Different Properties and Applications: 

Silicon powder: 

Significantly improve the performance of compression resistance, flexure resistance, permeability resistance, corrosion resistance, impact resistance and wear resistance. 

It has the function of retaining water, preventing segregation, and bleeding, and greatly reducing concrete pumping resistance. 

Significantly prolong the service life of the concrete. 

The ground ash of shotcrete and castable is greatly reduced and the thickness of the single shotcrete layer is increased. 

It is the necessary component of high-strength concrete and the engineering application of concrete.

Can be used in semiconductor technology. 

High purity silicon (> 99.99%) is used in computer microchips, transistors, and solar cells. 

It can be used as raw material for reaction bonded silicon nitride (RBSN) and metal infiltration for high purity silicon carbide 

Metal silicon powder: 

Metal silicon powder has strong high-temperature resistance, so many times in refractory materials and powder metallurgy production, adding an appropriate amount of metal silicon powder can greatly improve the high-temperature resistance of metal silicon powder. 

Silicon metal powder is usually added in the production of some wear-resistant castings to improve the wear resistance of castings. 

It is also deoxidizing. 

Silicon metal powder can be used as a deoxidizer and alloy additive in steelmaking. At the same time, the production of casting metal silicon powder can also be used for inoculation.

Silicon Powder Price

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What is Zirconium Diboride

Zirconium diboride is a hexagonal crystal form, and its metalloid structure determines that zirconium diboride has good conductivity and mobility, while the Zr-B ionic bond and B-B covalent bond between the boron atomic plane and the zirconium atomic plane The strong bond determines the high melting point, high hardness and high stability of this material. At the same time, it also has good flame retardancy, heat resistance, oxidation resistance, corrosion resistance and other characteristics. Its density is 6.085-6.17, its melting point is 3040℃, its Rockwell hardness is 88-91, and its compressive strength is 1555.3Gpa.

The manufacturing method of zirconium boride includes: reacting boron trifluoride with zirconium, heating zirconium dioxide, boric acid and carbon in a high temperature furnace to 1900 °C, heating elemental boron and zirconium oxide to 1000-1000 °C under vacuum. 1750°C.

1. Preparation of high-purity zirconium diboride

Vapor-phase halides were deposited onto heated tungsten substrates in nitrogen.

2. Metal borides prepared by molten electrolysis

The composition of the electrolytic cell is CaO+CaF2+2B2O3+1/6 ZrO2, the temperature is 1 000 ℃, the purity of the product ZrB2 is 99.6%, the purest boride ZrB2 is obtained by the molten electrolysis method, and the impurity is graphite. The composition of the electrolytic cell and the ratio of a small amount of metal or boron, metal to boron in the boride can be controlled by the ratio of metal oxide to boron oxide in the electrolytic cell.

3. The method of industrial synthesis of zirconium boride is mainly the method of reducing boride with zirconia, and the reducing agent can be carbon or boron carbide (B4C). It is better to use boron carbide than carbon because the reduction of zirconium boride powder with carbon as the source of boron is boron anhydride, no matter whether it is synthesized by arc melting or solid phase reaction, because the boiling point of boron anhydride is very low, it will volatilize a lot when it is above 1 000 ℃. The chemical composition of the synthesized zirconium boride varies greatly, and the temperature of the melting method is high and the electrofusion rate is fast, which will cause serious contamination of the product by the Shimo crucible and may produce a large amount of by-product zirconium carbide. The single-phase product of zirconium diboride can be prepared by using boron carbide as reducing agent.

Metal compounds of boron such as boron (lithium) aluminum, titanium boride, boron nitride and boron carbide are used in the atomic energy industry, high-speed cutting in the aerospace industry, as well as in the telecommunications and electronics industries; elemental boron is also used in the manufacture of special alloys and automotive safety. airbag.

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Nano metals have poor stability due to the introduction of a large number of grain boundaries. Generally speaking, the growth temperature of nanocrystalline grains is much lower than the recrystallization temperature of coarse crystals, and some nanocrystalline pure metals grow up even at room temperature. Poor stability has become a significant bottleneck restricting the preparation and application of nanometals. The traditional method of stabilizing nanocrystals is mainly to reduce the interfacial energy or drag the grain boundary migration through alloying.

In 2018, nanometal scientists from the Chinese Academy of Sciences discovered the abnormal grain size effect of thermal stability of nanocrystals in nanocrystalline pure copper and pure aluminum prepared by plastic deformation, that is, smaller than the critical size. The deformation mechanism changes from dominated by dislocations to governed by incomplete fractures, the grain boundary relaxation mechanism is activated, and the stability of nanocrystals does not decrease but rises. Subsequently, they found that, despite the difference in the internal mechanism of grain boundary migration under heating conditions, this abnormal grain size effect also exists in the mechanical stability of nanocrystals under stress.

It is understood that in some nanometals, such as pure copper, nano-grains grow even at room temperature. This inherent instability brings difficulties to the preparation of nano-metallic materials; on the other hand, it also limits the practical application of nanometals.

The study also found that the abnormal stability of nanocrystals not only occurs in low- and mid-level fault energy metals such as pure copper but also in high-level fault-energy pure nickel. The discovery of ultra-high stability nanocrystals is not only significant for us to understand the deformation mechanism of nanocrystals and the behavior of grain boundaries at nanometer size but also shows the possibility of developing nanocrystals used at high temperatures.

However, the grain size of the pure metals prepared by the currently commonly used severe plastic deformation methods (such as equal channel extrusion, lap rolling, etc.) is usually in the submicron scale, and it is challenging to initiate the grain boundary relaxation mechanism during processing. For example, the grain size of pure copper prepared by severe plastic deformation is mostly in the range of 100-200 nm, and its stability is poor. Recently, researchers have discovered that rapid temperature increase can introduce annealing twins into nanocrystalline copper, thereby achieving "thermal relaxation" of the nanocrystalline grain boundaries and improving the thermal stability of the nanocrystals. One of the difficulties faced by the introduction of annealing twins in nanocrystalline copper is that unstable nanocrystals have a grain growth stability of only 393 K, which is far below the temperature at which annealing twins are generated (——523 K) During the heating process, twins are not produced, and the grains have grown up. Based on the Kissinger effect, the researchers proposed that increasing the heating rate can increase the grain growth temperature without affecting the twinning growth temperature. Therefore, rapid temperature rise not only avoids grain growth but also produces growth twins. The pure Cu with a grain size of about 80 nm was rapidly heated to 523 K at a rate of 160 K / min for 15 minutes and then cooled. The grain size of the material did not change significantly, but the number of twins increased significantly. Like deformed twins, these grown twins can also relax the grain boundaries and enhance the thermal stability of the nanocrystals. After heat treatment, the apparent growth temperature of the nanocrystals increased from below 393 K to above 773 K.

The thermal relaxation method of rapid temperature increase to improve the stability of nanocrystals can be used to enhance the security of submicron and nanocrystals obtained by general severe plastic deformation and is of great significance for the development of highly stable nanomaterials and the promotion of nanometal applications.

Figure 1. Nanocrystalline copper stabilized by rapid heating. (A) Typical cross-sectional scanning electron micrographs of the surface gradient nanostructures of the as-prepared samples and samples heated to 523K at different heating rates (1, 80, 160K / min), respectively. (BD) Preparation samples and samples after heat treatment at different heating rates from the surface-typical transmission photos of nanocrystals at a depth of 25 μm (corresponding depth is shown in the dotted frame in Figure A, the average grain size of the prepared samples at this depth About 80nm). (E) The range of grain size corresponding to the surface stabilized nanocrystals in the example after heating to 523K at different heating rates. The reliable and hollow dots in the figure, respectively, represent the grain size corresponding to the upper and lower boundaries of the stable nanocrystalline layer observed in the experiment. The dotted line represents the upper limit of the average grain size of the stable nanocrystals during the 523K heat treatment of the prepared sample (D * —— 60nm ), The error bar refers to the standard statistical error of the average grain size.

Figure 2. After rapid heating, a large number of twins are formed inside the nanocrystals, and the grain boundaries are planarized. (A) A typical high-resolution photo of nanocrystals in the area shown in Figure 1D. The inset in the upper left corner is an atomic image of the nano twins in the grain. (B, C) Typical grain boundary character distribution in the sample after preparation and heating to 523K at a heating rate of 160K / min. Different colors represent different types of grain boundaries, red is the twin grain boundary, gray is the small-angle grain boundary, black is the significant conventional angle grain boundary, and other colors are other individual bulky lattice interfaces (Σ <29). (D, E) High-resolution photos of typical grain boundaries in the area shown in Figure 1D. The illustration in the upper left corner is an enlarged view of the solid red frame.