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Carbide pcd tool

Choose a reasonable process parameters, ceramic binder diamond grinding wheel grinding single crystal diamond, grinding efficiency than the metal binder grinding wheel high, wear ratio is very small, low processing costs, so the use of ceramic binder grinding wheel grinding single crystal can greatly improve Break day grinding efficiency. In the grinding PCD tool, due to the resin binder is soft, easy to deformation when grinding, can not effectively grinding PCD tool; metal binder due to the combination of abrasive grain is too strong and abrasive self-sharpening, grinding Low efficiency, and the metal binder grinding wheel will cause the PCD tool edge to produce serious damage to the zuizui; comprehensive grinding efficiency, abrasive durability and workpiece surface processing quality, ceramic binder diamond grinding wheel is a suitable choice for grinding PCD tool zui.

Diamond as a superhard tool material has been used in cutting for hundreds of years. In the course of the development of the tool, from the late nineteenth century to the middle of the twentieth century, the tool material to high-speed steel as the main representative; 1927 Germany shou first developed carbide material and widely used; the twentieth century, the fifties, Sweden And the United States were synthetic synthetic diamond, cutting tools from the step into the superhard material as the representative of the period.

Internal enterprises should continue to innovate advanced technology, and constantly improve the production process, reduce production costs and improve economic efficiency. Take the road of group or joint enterprise, set up several large enterprise groups, guide the development of the industry, create their own brand, and actively participate in international competition. Relying on scientific and technological progress, increase investment in science and technology, update equipment, pay close attention to new technologies, new technology, new product research and promotion, improve tool base material usage, accelerate the development of China's hardware industry, further improve economic efficiency and overall technical level.

Composition of tungsten carbide

Tungsten carbide is a compound of tungsten and carbon. For the black hexagonal crystal, a metallic luster, hardness and diamond similar to the electric, heat a good conductor. Tungsten carbide is not soluble in water, hydrochloric acid and sulfuric acid, soluble in nitric acid - hydrofluoric acid mixed acid. Pure tungsten carbide fragile, if mixed with a small amount of titanium, cobalt and other metals, can reduce the brittle. Tungsten carbide used as a steel cutting tool, often added titanium carbide, tantalum carbide or their mixture, in order to improve the anti-explosive ability. The chemical properties of tungsten carbide are stable. Tungsten Carbide Powder Used in Carbide Production Materials.

From 1893, the German scientists on the use of tungsten trioxide and carbon in the electric furnace with the heating method to produce high temperature tungsten carbide, and trying to use its high melting point, high hardness and other characteristics to draw the drawing die, in order to replace the diamond material The But because of tungsten carbide tritious, easy to crack and low toughness reasons, has been unable to get industrial applications. In the 1920s, the German scientist Karl Schroter found that pure tungsten carbide could not adapt to the intense stress changes formed during the drawing process. Only by adding low melting metal to WC can the blank Has a certain toughness. In 1923, Schroter first proposed a method of powder metallurgy by mixing tungsten carbide with a small amount of iron metal (iron, nickel, cobalt) and then pressing and sintering at a temperature above 1300 ° C to produce a hardness alloy Of the patent.

The tungsten powder having an average particle diameter of 3 to 5 m and the carbon black having an average particle diameter of 3 to 5 m are dry-mixed with a ball mill with a metal tungsten and carbon as a raw material, and the mixture is thoroughly mixed and then put into a graphite disk by press molding, Or induction furnace heated to 1400 ~ 1700 ℃, preferably controlled at 1550 ~ 1650 ℃. In the hydrogen stream, W2C is initially generated and continues to react at high temperatures to form WC. Or first hexacarbonyl tungsten in the 650 ~ 1000 ℃, CO atmosphere thermal decomposition of tungsten powder, and then with carbon monoxide at 1150 ℃ reaction WC, the temperature above this temperature can generate W2C.

Tungsten oxide (average particle size 3 ~ 5μm) was prepared by hydrogenation of tungsten trioxide WO3. And then the tungsten powder and carbon black by equimolar mixture (mixed with a ball mill for about 10h), in about 1t / cm2 pressure under pressure molding. The pressurized molding block is placed in a graphite disk or crucible and heated to a temperature of 1400 to 1700 ° C (preferably 1550 to 1650) in a hydrogen stream (using pure hydrogen having a dew point of -35 ° C) using a graphite resistance furnace or an induction furnace C), so that carbonization is generated WC. The reaction proceeds from the periphery of the tungsten particles because W2C is generated at the beginning of the reaction, and unreacted W and the intermediate product W2C remain in addition to the WC due to the incomplete reaction (mainly the reaction temperature). So it must be heated to the above high temperature. The maximum temperature should be determined based on the particle size of the raw tungsten. If coarse particles having an average particle size of about 150 m are used, the reaction is carried out at a high temperature of 1550 to 1650C.

Carbide tungsten carbide WC particle size requirements, according to different uses of cemented carbide, the use of different sizes of tungsten carbide; carbide cutting tools, such as cutting blade blade V-CUT knife, finishing alloy with ultra-fine Fine particles of tungsten carbide; rough processing alloy used in the granular tungsten carbide; gravity cutting and heavy cutting of the alloy using coarse particles of tungsten carbide as raw materials; mining tools rock hardness high impact load large use of coarse particles of tungsten carbide; rock impact small impact load Small, the use of particles in the tungsten carbide as raw materials wear parts; when stressed its wear resistance and surface finish, the use of ultra-fine sub-fine particles of tungsten carbide as raw materials; impact resistance tools used in coarse particles of tungsten carbide raw materials the Lord. [6] Tungsten carbide theoretical carbon content of 6.128% (atomic 50%), when the tungsten carbide carbon content is greater than the theoretical carbon content of tungsten carbide in the presence of free carbon (WC + C), the presence of free carbon sintering around its carbonation Tungsten carbide grain growth, resulting in uneven carbide grain; tungsten carbide generally require high carbon (≥ 6.07%) free carbon (≤ 0.05%), the total carbon is determined by the carbide production process and use. [6] Under normal circumstances, the total carbon content of vacuum tungsten carbide for vacuum sintering is mainly determined by the amount of oxygen in the briquette before sintering with an increase of 0.75 parts of carbon, ie, WC total carbon = 6.13% + oxygen content% x 0.75 (assuming sintering Furnace is neutral atmosphere In fact most of the vacuum furnace for the carburizing atmosphere used tungsten carbide total carbon is less than the calculated value). [6] The total carbon content of tungsten carbide in China is roughly divided into three kinds of paraffin process. The total carbon content of tungsten carbide for vacuum sintering is about 6.18 ± 0.03% (free carbon will increase). The total carbon content of tungsten carbide 6.13 ± 0.03% Rubber process Hydrogenation of tungsten carbide for hydrogen Hydrogenation = 5.90 ± 0.03% The above process is sometimes crossed so as to determine the total carbon content of the tungsten carbide according to the specific situation. [6] Different use of different cobalt content, different grain size of the alloy used WC total carbon can do some minor adjustments. Low cobalt alloy can choose the total carbon high tungsten carbide, high cobalt alloy can choose the total carbon low tungsten carbide. In short, the specific requirements of the use of carbide on the tungsten carbide particle size requirements are also different.

Application areas: Large quantities for high-speed cutting tools, furnace structural materials, jet engine parts, metal ceramic materials, such as resistance heating elements. [5] Used in the manufacture of cutting tools, wear parts, copper, cobalt, bismuth and other metal melting crucible, wear-resistant semiconductor film. [5] Used as super-hard tool materials, wear-resistant materials. It forms a solid solution with many carbides. WC-TiC-Co carbide cutting tools have been widely used. It can also be used as a modified additive for NbC-C and TaC-C ternary system carbides, which can reduce the sintering temperature and maintain excellent performance and can be used as a spacecraft. [7] The tungsten carbide (WC) powder was synthesized by using tungsten anhydride (WO3) and graphite at a high temperature of 1400 ~ 1600 ℃ in a reducing atmosphere. And then by hot pressing sintering or hot isostatic pressing sintering can be made of dense ceramic products. [1]

Tungsten carbide spray corrugated Can cause bronchial inflammation, bronchiolitis, atresia bronchitis and atrophic emphysema. Tungsten carbide can cause lung lymphoid tissue cells proliferative response, and the gradual emergence of hardening. The vessel wall is thickened and homogenized. Work contact with tungsten carbide dust in the gastrointestinal tract dysfunction, kidney irritation, upper respiratory tract signs of inflammation. The maximum allowable concentration of tungsten carbide is 6mg / m3. The maximum allowable concentration of soluble tungsten compounds (tungsten) in the United States is 1 mg / m3, and the insoluble tungsten compounds (tungsten) are 5 mg / m3. [8] Security: Use to meet the requirements of the anti-virus masks, dust clothing, gloves, glasses. In the production of all stages to prevent dust leakage. Workers should do the pre-employment physical examination and check them once a year. Upper respiratory tract obvious symptoms, to temporarily mobilize the work, out of contact with tungsten. When the occurrence of pulmonary sclerosis or external respiratory dysfunction, to be transferred from work. [8] Storage: should be stored in a cool, dry warehouse, the transport should pay attention to the packaging container intact, rain and anti-sun exposure. [5] Packaging storage and transportation: the product using iron drum (plastic drum), lined with polyethylene plastic bag sealed packaging, net weight per bag shall not exceed 50kg. Outside the drum should be "moisture" and "up" and other words. Products should be stored in a cool, dry warehouse, the transport should pay attention to the packaging container intact, rain and anti-sun exposure. [8]

Carbide Definition

Carbide is made of a refractory metal hard compound and a metal binder through a powder metallurgy process. Among them, refractory metal compounds include tungsten carbide (WC), titanium carbide (TiC), niobium carbide (NbC), tantalum carbide (TaC) and so on. The bonding metals include iron (Fe), cobalt (Co), nickel (Ni), and the like.

  • 1.1 Carbide performance and use Carbide has a high melting point, high hardness, high yield strength; good wear resistance, thermal conductivity, corrosion resistance, oxidation resistance and other special excellent performance, widely used in cutting tools , Wear parts, mold materials, mining teeth, oil control parts and so on.
  • 1.2 Carbide classification in accordance with the use of carbide, can be divided into:
  • (1) cutting tools: used as a variety of cutting tools. Such as: welding tools, CNC tool, the overall carbide drill, PCB and so on. China's cutting tools, carbide dosage accounts for about 1/3 of the entire carbide production.
  • (2) mining tools: mainly used for the impact of drilling with the drill bit, geological exploration with the drill, mine oilfield with the hole drilling, cone drilling and cutting machine picking, building materials, such as impact drill. China's geotextile carbide carbide carbide production accounts for about 25% of the total.
  • (3) mold: drawing die, cold heading die, extrusion die, stamping die, drawing die and roll. Used for all kinds of mold carbide accounted for about 8% of the total carbide production,
  • (4) structural parts: such as compressor piston, lathe chuck, grinding machine mandrel, bearing journal and so on.
  • (5) wear-resistant parts: such as nozzles, rails, plungers, balls, tire anti-skid nail, snow snow board.
  • (6) high pressure high temperature with the cavity: the top hammer, cylinder and other products.
  • (7) other uses: such as bracelet, case, senior luggage zipper head, carbide trademark and so on.

3 Cemented Carbide Performance and Application

Carbide performance indicators: including material testing and appearance size detection.

Density D-density is the weight per unit volume;

Hardness HRA, HV-characterization of alloy resistance to deformation and wear;

Relative Magnetic Saturation Ms% - Modern Carbide Production Total Carbon Control is achieved by magnetic saturation of the alloy;

The coercive force Hc - is mainly determined by the thickness of the cobalt layer, and is related to the uniformity of cobalt distribution and the carbon content of the alloy.

The flexural strength TRS-characterizes the ultimate strength of the alloy under the bending load.

Impact toughness ak - the ratio of the impact energy consumed when the specimen is broken to the cross-sectional area of ​​the test specimen. The greater the solid solubility, the greater the impact toughness. The

Metallographic - Microstructure and Defects. Microstructural features include alloy phase composition, average grain size and particle size composition, cobalt layer thickness and its distribution. Defects include porosity, inclusion, polycrystalline, coarse, mixed, cobalt pool, carburizing, decarburization and so on.

Size - mainly refers to the size of the alloy and geometric tolerances.

Appearance - mainly refers to the appearance of the alloy color, gap, drop, pits and so on.

Synthesis and Application of Nanometer Cemented Carbide Materials in Industrialization

Recently, by the Hunan Bo Yun Oriental Powder Metallurgy Co., Ltd. and other units bear the 863 plan "nano-carbide materials industrial technology and application (2013AA032001)" subject through technical acceptance. In the 863 plan new materials technology support, research and development and production of a series of nano-cemented carbide materials and products, some nano-carbide has achieved initial industrialization, and in a number of engineering areas for demonstration applications.

To WC, TiC as the representative of the carbide is widely used in aerospace, machinery manufacturing, oil drilling and defense industry and other industrial fields, is an irreplaceable basic and strategic materials. Before the implementation of this project, China can not produce nano-carbide products.

From 2013 onwards, Hunan Boyun Oriental Powder Metallurgy Co., Ltd., Beijing University of Technology, Guangzhou Rui De Sen Special Ceramics Technology Co., Ltd., Beijing North Hard Carbide Co., Ltd., South China University of Technology, Guangzhou Red Daily Gas Appliance Co., Ltd. and other units The advanced technology of WC, WC-Co and TiC nanocomposites was developed to break through the key technologies such as high performance, high efficiency, low cost and scale scale. The nano-WC-Co composite powder with annual capacity of 50 tons was built, Thermal spraying materials, low-pressure sintered cemented carbide, high-precision precision tools with nano-carbide rods and annual production capacity of more than 10 tons of continuous microwave synthesis of nano-TiC powder industrial production demonstration line.

At present, with independent intellectual property rights of nano-carbide products in aviation, communications, precision manufacturing, electronics, coal, steel and other areas of demonstration applications, to fill the gaps in the domestic, to significantly enhance the technical level of China's cement industry, Carbide high-end industrial development, efficient use of China's superior resources is of great significance.