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Diamond-copper/steel matrix abrasive composites were prepared by the roll-bonding technique. Firstly, the effects of the roll-bonding technical parameters (including sintering parameters, rolling parameters, and the component content) on the interfacial bonding strength in the composites were researched. Then, the surface macroscopic characteristics of the composites and the microstructures of the bonding interfaces were observed. The static compressive strength of the diamonds in the composites and the grinding performance of the composites were measured. Finally, the mechanisms for the effects of the roll-bonding technical parameters on the interfacial bonding strength were explored. The results showed that with increasing those parameters, the interfacial bonding strength between diamonds and the matrices displayed an initial increase and then a significant decrease. Furthermore, the optimal interfacial bonding strength (11.4 kN/m) and an excellent grinding performance (abrasive ratio of 23.2) were obtained from the diamond-steel matrix composites containing 10 vol% binder and 25% concentration of diamonds, when sintered at the temperature of 900 °C for holding time of 30 min and cold rolled at the reduction rate of 70%. The composites prepared with the optimum technical parameters had acceptable surface smoothness. In addition, the diamonds could be dispersed homogeneously in the matrices and firmly adhered to the substrates. When the diamond concentration was 25% in cold-rolling, the diamond-steel matrix composites showed better grinding performance. By improving the pressure condition of metallurgical bonding between diamonds and metal matrices from static pressure to rolling dynamic pressure, the sintering condition of temperature and holding time can be reduced and shortened, and the sintering condition effect on the interfacial bonding can be weaken. Thus, the application of the roll-bonding technique to the preparation of diamond-metal matrix composites could effectively avoid the thermal damage of diamonds caused by sintering process. [ABSTRACT FROM AUTHOR]

Abstract: Silica-coated ultrafine diamond (UFD/SiO2) composites were prepared, which were core/shell structures with amorphous silica shell of approximately 5nm thickness. Contrasting to the pristine UFDs, the dispersion stability of the UFD/SiO2 composites was improved greatly in the multi-component inorganic salts aqueous solution, and the chemical compositions of the ceramic matrix were introduced by multi-component inorganic salts. Meanwhile, the oxidation resistance temperature of the coated UFDs was also increased by around 101.0°C. Furthermore, by using the polyacrylamide gel method and hot-press sintering process, ceramic composites were fabricated with the UFD/SiO2 aqueous suspension containing multi-component inorganic salts. The results indicated that the UFDs coated with silica could be dispersed uniformly in ceramic matrix, where no obvious UFD agglomerates were observed. [Copyright &y& Elsevier]