Spark plasma sintering of Al₂O₃-cBN/SiO₂ composite using RCVD SiO₂ thin layer coated cBN powder

抄録

SiO₂ thin layer was coated on cBN (cBN/SiO₂) by rotary chemical vapor deposition (RCVD) using tetraethoxysilane (TEOS) as a precursor. Al₂O₃-cBN/SiO₂ composite was compacted by spark plasma sintering (SPS). The phase transformation temperature of cBN to hBN in Al₂O₃-cBN/SiO₂ composite was 1773 K, 200 and 100 K higher than that in Al₂O₃-cBN/Ni and Al₂O₃-cBN composites, respectively. The highest relative density of Al₂O₃-cBN/SiO₂ composite was 99.5% at 1673 K and 30 vol% cBN with 1.9 mass% SiO₂. The maximum hardness of Al₂O₃-cBN/SiO₂ was 28 GPa for Al₂O₃-30 vol% cBN/SiO₂ (SiO₂ content: 1.9 mass%) composite sintered at 1673 K and 100 MPa.