Abstract
Diamond/Al composites containing B4C-coated and uncoated diamond particles were prepared by powder metallurgy. The microstructure, bending strength and thermal conductivity were characterized considering the B4C addition and diamond fraction. The influence of B4C coating and fraction of diamond on both bending strength and thermal conductivity were investigated. The bending strength increased with decreasing diamond fraction. Moreover, addition of B4C coating led to an obvious increase in bending strength. The peak value at 261.2 MPa was achieved in the composite with 30 vt.% B4C-coated diamond particles, which was about twice of that for 30 vt.% uncoated diamond/Al composite (140.1 MPa). The thermal conductivity enhanced with the increase in diamond fraction, and the highest value (352.7 W/m·K) was obtained in the composite with 50 vt.% B4C-coated diamond particles. Plating B4C on diamond gave rise to the enhancement in bending strength and thermal conductivity for diamond/Al composites, because of the improvement of the interfacial bonding between diamond and aluminum matrix.
Highlights
Metal matrix composites (MMCs) reinforced with diamond have achieved much attention in variety applications such as cut-off wheels and drills for concrete cutting, tunneling or oil exploration, due to its high hardness and grinding ability[1,2,3,4,5]
The diamond/Al composites with different volume fraction of B4C-coated and uncoated diamond particles were prepared by powder metallurgy
The grain sizes of the B4C coating calculated from Williamson-Hall plot is 64 nm
Summary
Metal matrix composites (MMCs) reinforced with diamond have achieved much attention in variety applications such as cut-off wheels and drills for concrete cutting, tunneling or oil exploration, due to its high hardness and grinding ability[1,2,3,4,5]. Feng et al.[7] reported that coating TiC was benefited to the enhancement of TC for diamond/Al composites, since Al4C3 and Ti3Al interfacial phase were formed during heating process, resulting in an improvement of combination between TiC-coated diamond and Al matrix. Boron carbide (B4C) is widely used as a reinforcement particle in aluminum alloy for improving strength, hardness and wear resistance[21,22,23,24,25]. A 100% improvement in wear resistance was achieved compared to the parent metal These results indicated that Al/B4C exhibited a strong interface. The B4C coating on diamond is conducive to obtain a dense diamond/Al composite due to the continual bonding interface The enhancements of both mechanical and thermal properties are dependent on the porosity and the interfacial gap width between diamond and aluminum matrix
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