Papers by Keyword: Machinable

Abstract: In this research, the SiC/Al/h-BN composite ceramics with different SiC grain size were fabricated by the method of preparing the machinable pre-sintered body through Plasma Activated Sintering (PAS), which has the advantage of complex shape formation for precision parts. By hardening treatment, the SiC/Al/h-BN composite ceramics would be changed to SiC/AlN composites, and the relatively higher hardness and mechanical properties could be obtained accordingly. The phase transformation and microstructure were observed and the mechanical and other properties were also measured. The results showed that, for different matrix SiC particle size, change tendency of the bending strength was different with the heat treatment temperature change. And the bending strength of composites with larger SiC grain size was higher than that with smaller SiC grain size.

Abstract: Ceramic composites containing BN and Al can be machined easily into complex shape, the hardness of the composites can also be improved by surface hardening process of in situ reaction between Al and BN. However, the reaction of Al and BN is a volume reduced one and the porosity will increase during the hardening treatment.. In order to solve this problem, a surface nitriding process was developed. Put the pre-sintering samples (with designed shapes) into a vacuum furnace in nitrogen atmosphere and reheated to high-temperature, so that the residual Al after pre-sintering would react with N2 completely, and change to AlN which has higher hardness. The phase transformation and microstructure were observed and the mechanical and other properties were also measured. The results showed that the surface nitriding process could increase the hardness, bending strength and density obviously. The porosity decreased sharply compared with the general hardening treatment.

Abstract: In order to obtain machinable ceramic with high hardness and strong mechanical properties, the SiC/Al/h-BN Composite Ceramics were fabricated by a new method which prepared the machinable pre-sintered body by Plasma Activated Sintering (PAS) and increased it's mechanical properties after hardening treatment. The results showed that the machinability and density of the pre-sintered h-BN/Al/SiC ceramic composites were excellent, and after hardening treatment, the mechanical properties (hardness, bending strength and density) increased obviously.

Abstract: Some useful characteristics, including strength, toughness, damage of machining, and propagation pattern of indentation cracks, were studied based on machinable 30 wt%LaPO4/ Al2O3 composites. Corresponding characteristics for Al2O3 ceramic were also concerned for comparing. The results supplied some elementary information for both use and further study of LaPO4/ Al2O3 composites.