研究目的
Investigating the problems of forming polycrystalline materials with a high level of physical-and-mechanical properties using the method of diamond powder sintering at high pressure.
研究成果
The study concludes that the sintering of diamond nanopowders under high pressure and high temperature can produce polycrystalline materials with high physical-and-mechanical properties. The effectiveness of tungsten and its compounds as activating additions is demonstrated, leading to the production of wear-resistant thermostable diamond nanocomposites. However, the study also identifies the need for further optimization to overcome limitations related to porosity and graphitization.
研究不足
The study highlights the challenges in eliminating porosity in sintered polycrystals and the partial graphitization of diamond particles during sintering. The counteraction of capillary forces to external pressure in the sintering of diamond nanopowders is identified as a significant limitation.
1：Experimental Design and Method Selection:
The study involves the sintering of diamond nanopowders under high pressure and high temperature conditions to form polycrystalline materials. The theoretical models and algorithms employed focus on the compacting mechanism of diamond nanopowders and the role of pore structure formations in sintering.
2：Sample Selection and Data Sources:
Diamond nanopowders of different genesis are used, with selection criteria based on their physical-and-mechanical properties and the presence of functional groups on the surface of particles.
3：List of Experimental Equipment and Materials:
High-pressure apparatus (HPA) of toroid type is used for sintering at pressures up to 8 GPa and temperatures ranging from 800 to 2300°C. Diamond nanopowders and tungsten or its compounds are the primary materials.
4：Experimental Procedures and Operational Workflow:
The process includes preparation of diamond powders (degassing and surface modification), compacting at room temperature, annealing in vacuum or inert gas, and sintering in HPA under specified pressure and temperature conditions.
5：Data Analysis Methods:
The study analyzes the density, hardness, and crack resistance of the sintered polycrystalline materials, using equations to describe the kinetics of diamond powder compacting under high pressure and high temperature.
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