Multiphase SiAlON-cBN Composites Prepared By Spark Plasma Sintering

In order to explore the possibility of producting PcBN at lower temperature andunder lower pressure, cBN/SiAlON composites were prepared by Spark Plasma Sinteringafter researching thermal stability of cBN and preparation of SiAlON. Binding betweencBN and SiAlON matrix were studied.Phases were indentified through XRD and raletive calculation was carried out.Density was measured by Archimedes method. Three-point bend tests were conducted togain flexural strength. Fracture surface and grain morphology of sintered samples wereobserved under FE-SEM. The hardness was obtained by FM-700hardness test machineand fracture toughness was obtained by Vicker’s indentation technique.In the explore experiments of SiAlON ceramic preparation, Investigated the impactof sinter point, heating rate, different types and proportion of Si₃N₄. Change the types andproportion of Si₃N₄can control the proportion of α/β-SiAlON easily. Sample sintered at1560℃,100℃/min, protect by N2with original Si₃N₄was90%-Si₃N₄and10%β-Si₃N₄posed better comprehensive properties, which fracture toughness flexural strength, andhardness were4.66Mpa·m^1/2,660.25MPa and17.93GPa, respectively.The results of cBN/SiAlON XRD showed that none of hBN was transformed by cBNin the sample. The density of the sample reduced with the increasing content of cBN, Thedensity was79.88%when50wt.%cBN content. Increasing the sintering can improve thedensity of the sample, the density improved from85.97%to91.42%bying the pressureimproved from30MPa to50MPa when40wt.%cBN content.