Fabrication of high thermal conductive Al–cBN ceramic sinters by high temperature high pressure method

Al–cBN ceramic sinters were fabricated by sintering micro-powder mixture of Al and cBN under high temperature and high pressure condition. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping analyses and laser flashing thermal conductivity measurements were performed to investigate the sintering properties and thermal conductivity of the Al–cBN ceramic sinters. XRD analysis revealed these Al–cBN ceramic sinters were composed of a large portion of cBN and of a small portion of AlN, and very little amount of AlB12 and hBN. Formation of boundary phase resulted in the rapid densification of the sinters, as well as the increase of their relative density with increasing Al additions. The Al–cBN ceramic sinters have a maximum thermal conductivity of about 1.94 W/cm K at room temperature and a much higher value of about 2.04 W/cm K at 200 °C. Their high thermal conductivity over that of AlN–hBN composites promise Al–cBN ceramic sinters favorite candidates as high efficiency heat sink materials for wide band gap semiconductors.

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