Enhancing densification capacity and properties of Al/diamond composites by partial liquid hot pressing

Al/50vol% diamond composites are fabricated by hot pressing with the assistance of partial liquid phase for favoring densification through the addition of elemental copper. Copper is introduced by pure powder and secondary deposited coating (a tungsten based layer is coated directly on the surface of diamond particles), respectively. The results show that density, bending strength and thermal conductivity of Al/diamond composites are improved when the liquid phase forms homogeneously in the matrix. As copper powder is added, the liquid phase spreads through the particle boundaries under the applied press during sintering, finally fills the interfaces and voids. While as copper coating is conducted, a better densification capacity and more enhanced properties of the composites are received. Moreover, a theoretical model is proposed to estimate the effect of different copper addition routes on thermal conductivity of the composites, and the results show a good agreement with the experimental data.