Composites containing ultrafine tungsten carbide/ cobalt (WC-Co) cemented carbides and 30 vol% cubic boron nitride (cBN) were fabricated by spark plasma sintering technique. The effect of cBN particles on the densification behavior, microstructure, and mechanical properties of the composites were investigated. According to SEM observation of microstructure, cBN particles are uniformly distributed and have excellent bonding with the cemented carbide matrix. Xray diffraction analysis shows that there is no indication of phase transformation from cBN to hBN. The addition of very hard dispersed cBN to the WC-Co promotes an increase of hardness, but a decrease of flexural strength. The density and the hardness of cBN-WC-Co composites increase with the increase of the sintering temperature. However, it has the highest hardness of 2,170 HV at 1,370°C and then the hardness decreases with the further increase of the sintering temperature.
Biomass has received tremendous attention as it is one of the best alternatives to replace the use of fossil fuels for energy generation. However, there are problems associated with the utilization of raw biomass which could be resolved through densification process. Besides, mixing between residues could produce a quality briquette, at the same time making good use on the biomass residues. Rice husk, sugarcane bagasse and spent coffee ground were selected as the biomass feedstocks for briquettes formation. The mixing ratios of 100:0, 80:20, 60:40, 20:80, 40:60 and 0:100 were used for three different combinations. The briquettes were then compacted at 300 bars and 150°C for 30 s. The mechanical properties of the briquettes were measured with respects to their shatter resistance, abrasive resistance as well as water resistance. The mechanical properties of the briquettes could be effectively improved by mixing between the residues as compared to the pure materials. The result showed that briquettes formed with 40: 60 of RH to SB; 20: 80 of RH to SCG and 20: 80 of SB to SCG were among the optimum mixing ratio for the respective combination fulfilling the specifications of the mechanical strength and durability.
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