以ZrO₂、Al₂O₃和铝粉作为结合剂,通过六面顶压机在高温(1 300~1 600℃)高压(5.5 GPa)条件下烧结制备聚晶立方氮化硼(PCBN)陶瓷,研究了烧结温度对陶瓷物相组成、力学性能以及加工离心铸铁时切削性能的影响。结果表明:不同温度烧结PCBN陶瓷的主晶相均为cBN、m-ZrO₂、t-ZrO₂、Al₂O₃、AlN和ZrN,结合相颗粒均匀地分散在cBN基体上;随着烧结温度的升高,cBN与结合相的结合更加紧密,陶瓷的相对密度、硬度、抗弯强度和断裂韧度增大;当烧结温度为1 600℃时,陶瓷的综合力学性能最好,硬度、抗弯强度和断裂韧度分别达到32.87 GPa,850.3 MPa,5.1 MPa·m^1/2;当烧结温度为1 400℃和1 500℃时,PCBN陶瓷刀具在切削离心铸铁棒总长度为10 km时,其后刀面磨损量仅分别为171,166 μm,切削性能较好。

With ZrO₂, Al₂O₃ and aluminum powder as binders, polycrystalline cubic boron nitride (PCBN) ceramics were sintered by using a six-anvil high-pressure apparatus at a high temperature (1 300-1 600 ℃) and high pressure (5.5 GPa). The effects of sintering temperature on the phase composition, mechanical properties and cutting performance when machining centrifugal cast iron of the ceramics were studied. The results show that the main crystal phases of the PCBN ceramics sintered at different temperatures were composed of cBN, m-ZrO₂, t-ZrO₂, Al₂O₃, AlN and ZrN, and the binding phase particles uniformly dispersed in the cBN matrix. With the increase of sintering temperature, The combination of cBN and the binder phase became tighter, and the relative density, hardness, flexural strength and fracture toughness of the ceramics increased. When the sintering temperature was 1 600 ℃, the ceramics had the best comprehensive mechanical properties, with microhardness, flexural strength and fracture toughness reaching 32.87 GPa, 850.3 MPa and 5.1 MPa·m^1/2, respectively. When the sintering temperature was 1 400 ℃ and 1 500 ℃, the flank wear amount of the PCBN ceramic tool was only 171, 166 μm, respectively, after cutting the centrifugal cast iron rod with a total length of 10 km, indicating that the cutting performance was relatively good.