Study Of The Interaction Among CBN And Bonding Components By SPS

With the development of machinery manufacturing technology, the PcBN tools became more and more important. The performance of PcBN not only depends on the quality of cBN, but also depends on the performance of binder.In this paper, element Al, Ti, Si or compound TiC, TiN, TiC0.7N0.3 used as binders were sintered with cBN at different temperature using spark plasma sintering (SPS). DSC, XRD, SEM, SAED and TEM were used to characterize the phases, microstructure and composition of the samples obtained.The cubic boron nitride micropowder was analyzed by DSC, the results showed that it was stable at inert atmosphere from room temperatue to 1500℃, on the other hand, at air atmosphere, it was easily oxidized and the cubic structure transformed to hexagonal structure at 1350℃.When cBN crystal was sintered by SPS, some hBN phase was observed. As the temperature rose, the transform ratio of cBN to hBN increased. Al could react with cBN at 1300 oC and formed AlN and AlB12. Ti could react with cBN obviously at 1300 oC and new phases of TiN and TiB2 was observed, and as the temperature rose, the amounts of products increased. Rhombohedral boron nitride (rBN) phase was observed in 1300 oC sintered Si-cBN sample. As the temperature rose, rBN was transformed into hBN. New phase of Si3N4 was observed in 1450 oC sintered Si-cBN sample.When cBN was sintered with TiC, TiN, or TiC0.7N0.3 at different temperature by SPS, and the hBN phase was observed in samples, so these compounds were not suggested to use as the binders of PcBN by SPS lonely.Using Si3N4-Al2O3-AlN-Y2O3 as binder, the compact PcBN was prepared at 1250~1450 oC by SPS.