Production method and application field of tungsten carbide WC powder

Overview of Tungsten Carbide WC Powder

Tungsten carbide is a compound composed of tungsten and carbon, with a molecular formula of WC and a molecular weight of 195.85. The most basic form of tungsten carbide is a fine gray powder, but it can be pressed into shapes through a process called sintering and used in industrial machinery, cutting tools, abrasives, armor-piercing bullets, and jewelry.

The stiffness of tungsten carbide is about twice that of steel, and the Young's modulus is about 530-700 GPa (77,000 to 102,000 ksi), which is twice the density of steel and almost between lead and gold. Its hardness is comparable to that of corundum (α-Al2O3). Only cubic boron nitride and diamond powder, grinding wheels and compounds containing high-hardness abrasives can be polished and finished.

Tungsten carbide is a black hexagonal crystal with metallic luster and hardness similar to diamond. It is a good conductor of electricity and heat. Tungsten carbide is insoluble in water, hydrochloric acid and sulfuric acid, but easily soluble in a mixed acid of nitric acid and hydrofluoric acid. Pure tungsten carbide is fragile. Adding a small amount of titanium, cobalt and other metals can reduce its brittleness. Tungsten carbide used as a steel tool is usually added with titanium carbide, tantalum carbide or their mixture to improve the anti-knock ability. Tungsten carbide is chemically stable. Tungsten carbide powder is used as a material for the production of cemented carbide.

Tungsten carbide WC powder production method

Using metal tungsten and carbon as raw materials, dry-mix tungsten powder with an average particle size of 3 to 5 μm and carbon black of the same amount with a ball mill, fully mix, press and shape it into a graphite plate, and then place it in a graphite resistance furnace Or it can be heated to 1400～1700℃ in an induction electric furnace, preferably 1550～1650℃. In the hydrogen stream, W2C is initially produced, and continues to react at high temperature to produce WC. Or firstly, tungsten hexacarbonyl is thermally decomposed at 650-1000°C in CO atmosphere to prepare tungsten powder, and then reacted with carbon monoxide at 1150°C to obtain WC. Temperatures higher than this temperature can generate W2C.

Tungsten trioxide WO3 is hydrogenated and reduced to prepare tungsten powder (average particle size 3～5μm). Then a mixture of tungsten powder and carbon black in an equimolar ratio (dry-blended with a ball mill for about 10 hours) is press-formed under a pressure of about 1t/cm2. Put the pressurized material block into a graphite pan or crucible, and heat it to 1400～1700℃ (preferably 1550～1650) in a hydrogen stream (using pure hydrogen with a dew point of -35℃) using a graphite resistance furnace or an induction electric furnace ℃), carburizing will produce WC. The reaction starts from around the tungsten particles, because W2C is generated at the beginning of the reaction, and because the reaction is incomplete (mainly because the reaction temperature is low), unreacted W and intermediate W2C remain besides WC. Therefore, it must be heated to the above-mentioned high temperature. The maximum temperature should be determined according to the particle size of raw tungsten. For coarse particles with an average particle size of about 150 μm, the reaction proceeds at a high temperature of 1550 to 1650°C.

Tungsten carbide WC grain size requirements of cemented carbide, according to different uses of cemented carbide, use different grain size tungsten carbide; cemented carbide cutting tools, such as cutting machine blade V-CUT knife, etc., the finishing alloy adopts ultra-fine sub Fine-grained tungsten carbide; medium-grained tungsten carbide is used for rough machining alloy; medium- and coarse-grained tungsten carbide is used as raw material for gravity cutting and heavy-duty cutting alloy; coarse-grained tungsten carbide is used for rock with high hardness and large impact load; small impact load for rock impact Small, medium-grain tungsten carbide is used as raw material for wear-resistant parts; when its wear resistance, pressure resistance and surface finish are emphasized, ultra-fine sub-fine and medium-grained tungsten carbide is used as raw material; impact-resistant tools use medium- and coarse-grained tungsten carbide raw materials host.

The theoretical carbon content of tungsten carbide is 6.128% (atomic 50%). When the carbon content of tungsten carbide is greater than the theoretical carbon content, free carbon (WC+C) appears in the tungsten carbide. The presence of free carbon will carbonize the surrounding area during sintering. The growth of tungsten grains results in uneven grains of cemented carbide; tungsten carbide generally requires high combined carbon (≥6.07%) free carbon (≤0.05%), and total carbon is determined by the production process and scope of use of cemented carbide.

Under normal circumstances, the total carbon of tungsten carbide used for vacuum sintering in paraffin wax process is mainly determined by the compound oxygen content in the briquette before sintering. One part of oxygen must be increased by 0.75 part of carbon, that is, WC total carbon = 6.13% + oxygen content% × 0.75 (assuming sintering The furnace is a neutral atmosphere. In fact, most vacuum furnaces use tungsten carbide for carburizing atmosphere. The total carbon is less than the calculated value).　

The total carbon content of tungsten carbide in China is roughly divided into three paraffin processes. The total carbon of tungsten carbide for vacuum sintering is about 6.18±0.03% (free carbon will increase). The total carbon content of tungsten carbide for paraffin process hydrogen sintering is 6.13±0.03 % Total carbon of tungsten carbide for hydrogen sintering in rubber process=5.90±0.03% The above processes are sometimes cross-processed. Therefore, the determination of total carbon of tungsten carbide should be based on specific conditions.

The total carbon of WC used in alloys with different application ranges, different cobalt contents and different grain sizes can be adjusted slightly. Low-cobalt alloys can choose tungsten carbide with higher total carbon, and high-cobalt alloys can choose tungsten carbide with lower total carbon. In short, the specific requirements of cemented carbide have different requirements for the particle size of tungsten carbide.

Application fields of tungsten carbide WC powder

Tungsten carbide is widely used as high-speed cutting tools, furnace body structural materials, jet engine parts, cermet materials, resistance heating elements, etc., used to manufacture cutting tools, wear-resistant parts, and smelt copper, cobalt, bismuth, and wear-resistant semiconductor films.

Tungsten carbide is used as super-hard tool material and wear-resistant material.

Tungsten carbide can form a solid solution with many carbides. WC-TiC-Co carbide tools are widely used.

Tungsten carbide can also be used as a modified additive for NbC-C and TaC-C ternary carbides, which can reduce the sintering temperature and maintain excellent performance. Can be used as aerospace materials.

Tungsten carbide (WC) powder can also be synthesized with anhydrous tungsten (WO3) and graphite in a reducing atmosphere at a high temperature of 1400 to 1600°C. Dense ceramic products can be obtained by hot pressing sintering or hot isostatic pressing sintering.

Tungsten carbide (WC) powder can also be used to produce high-performance nanocrystalline or ultrafine keratin alloys, hard-surface wear-resistant spraying and petrochemical cracking catalysts; chipless molding tools; cutting tools; mining costs; nanocomposites (used to improve Hardness, strength and wear resistance); corrosion-resistant coatings; wear-resistant coatings; corrosion-resistant coatings; wear-resistant parts.

Tungsten carbide WC powder price

The price of tungsten carbide WC powder will vary randomly with the production cost of tungsten carbide WC powder, transportation cost, international situation, exchange rate and market supply and demand of tungsten carbide WC powder. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for tungsten carbide WC powder, please feel free to send an inquiry to get the latest price of tungsten carbide WC powder.

Tungsten carbide WC powder supplier

As a global supplier of tungsten carbide WC powder, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced technology and engineering materials. The company has successfully developed a series of powder materials (including oxides, carbides, nitrides, single metals, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.