Thermal properties of polycrystalline cubic boron nitride sintered under high pressure condition

• Main Authors: Leng Chunwei, Hu Xiaojun, Xie Hongliang, Shen Chunhua
• Format: Article
• Language: English
• Published: International Institute for the Science of Sintering, Beograd 2018-01-01
• Series: Science of Sintering
• Subjects: Cubic boron nitride; High-pressure sintering; Thermal conductivity; Thermal expansion coefficient; Bending strength
• Online Access: http://www.doiserbia.nb.rs/img/doi/0350-820X/2018/0350-820X1804401L.pdf

The excellent thermal and chemical properties of cubic boron nitride (cBN) indicate that it is potential materials to prepare the thermal dissipate substrate applied in the electronic packaging. The thermal properties of polycrystalline cBN ceramics, however, have not been fully investigated. We report the first sintering experiment on preparing polycrystalline cBN ceramics using cBN powder as starting material without any sintering aids. The microstructure and high bending strength show that the strong combination was achieved among the crystal grains. The measured results, including density, thermal conductivity and thermal expansion coefficient, reveal that the properties of this ceramics depend on the grain size of starting crystal cBN. The PcBN ceramics has low thermal expansion coefficient extremely matching to that of silicon and exhibits moderate thermal conductivity due to its low density and the existence of low thermal conductive phase of hexagonal boron nitride.