Recently, the St. Petersburg Materials Science and Technology Research Center has developed a new method for producing diamond composite materials: diamond composites of large size and desired shape can be obtained without high pressure.
Generally, industrial superhard and high-strength materials are composed of diamond composite materials, that is, diamonds are embedded in a certain base material and obtained by artificial synthesis. Therefore, the performance of such a base material is very high. First of all, the material is required to have the characteristics of high hardness, high strength and good wear resistance. Secondly, the chemical structure of the material is complete and can be firmly bonded to the diamond under chemical action. At the same time, the physical properties of the substrate material are similar to those of diamond, otherwise the material synthesized under external pressure may break. The nature of the carbide is best suited to act as such a material. They have strong hardness, wear resistance, thermal stability and good thermal conductivity. The higher the thermal conductivity, the less likely the workpiece will break if the temperature difference changes greatly. However, diamond composites cannot be obtained by sintering conventionally sintered diamonds with silicon carbide because high temperatures are required in this process, and diamonds are converted to graphite at high temperatures. Of course, it is also possible to synthesize diamond and silicon carbide by a high pressure method to obtain a composite material, but this process requires a pressure of 8.5 gigapascals. Therefore, it is not feasible to develop a diamond composite of a large size and a desired shape in a high pressure chamber by a high pressure method, and the cost will be very expensive.
The new method used by Russian experts in the development of diamond composites is to first process the diamond into micron-sized particles and extrude them into the desired shape and size, then heat them in a vacuum while immersing them in liquid silicon. At this point, the surface of the diamond is converted to graphite-like carbon and interacts with liquid silicon. The resulting article will be a complete composite of diamond powder trapped between silicon carbide, which can be large in size and optional in shape, which is not possible with other methods.
Generally, industrial superhard and high-strength materials are composed of diamond composite materials, that is, diamonds are embedded in a certain base material and obtained by artificial synthesis. Therefore, the performance of such a base material is very high. First of all, the material is required to have the characteristics of high hardness, high strength and good wear resistance. Secondly, the chemical structure of the material is complete and can be firmly bonded to the diamond under chemical action. At the same time, the physical properties of the substrate material are similar to those of diamond, otherwise the material synthesized under external pressure may break. The nature of the carbide is best suited to act as such a material. They have strong hardness, wear resistance, thermal stability and good thermal conductivity. The higher the thermal conductivity, the less likely the workpiece will break if the temperature difference changes greatly. However, diamond composites cannot be obtained by sintering conventionally sintered diamonds with silicon carbide because high temperatures are required in this process, and diamonds are converted to graphite at high temperatures. Of course, it is also possible to synthesize diamond and silicon carbide by a high pressure method to obtain a composite material, but this process requires a pressure of 8.5 gigapascals. Therefore, it is not feasible to develop a diamond composite of a large size and a desired shape in a high pressure chamber by a high pressure method, and the cost will be very expensive.
The new method used by Russian experts in the development of diamond composites is to first process the diamond into micron-sized particles and extrude them into the desired shape and size, then heat them in a vacuum while immersing them in liquid silicon. At this point, the surface of the diamond is converted to graphite-like carbon and interacts with liquid silicon. The resulting article will be a complete composite of diamond powder trapped between silicon carbide, which can be large in size and optional in shape, which is not possible with other methods.
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