A Study Of PcBN Compacts With Different Binders

The paper introduced the development of superhard materials first, To the development and application of PcBN and cBN, it has detailed illustration. The assembly way of synthesized PcBN is very important, The good ways have important influence to the result of experiment and the operation of six-anvil hydraulic press. The task changes the electric conduction material to improve on the assembly way first. The molybdenum piece and graphite columns with different diameter are used to conduct the electricity. To investigate how they controlled the cavity temperature and the hammer temperature. when the electric conduction material is molybdenum piece, the resistance is low,but with the time increase it become more and more high,and than it has a big change,so the experiment is stopped; when the electric conduction material is graphite column with diameter 4mm,the resistance increases high also,at last it has a big change also,so the experiment is stopped; when the electric conduction materials are graphite column with diameter 6mm and 8mm,the experiment is all right,and the graphite column with diameter 8mm has more excellency: the calefaction parameter is stabilization, the heat is hoist quickly and the hammer temperature is low; when the electric conduction material is graphite column with diameter 10mm,the favorable fact is the low resistance, the adverse fact shows the temperature of hammer is high,it prove the heat insulation effect is not good, so compares the experiments , the electric conduction material is used with the graphite column with diameter 8mm.because it's calefaction parameter is stabilization,the heat is hoist quickly and the hammer temperature is low.PcBN is sythesis by cBN powder, and specified proportion binder sintered on WC-16%Co substrate during high pressure and high temperature sintering. The binder is important in the synthsis of PcBN, The specified proportion binder can reduce sintering pressure and temperature, it also perfects the performance of PcBN. TiN,TiN and Al,AlN as the binders to sintering PcBN with high pressure and high temperature are investigated in this paper, the sintering pressure is 5GPa and the temperature is 1200℃-1600℃,it do hardness text. SEM and XRD. cutting text to the sintered samples.The experiment indicates that PcBN's microhardness is very low with the binder of TiN,At 1600℃,cBN and TiN retaine their original powder state. they like being mixed together mechanical under press. When do the cutting test, the cutting tool appeares serious collapse,but the production of PcBN cutting tool with the binder of TiN is usual,this experiment is failure ,perhapse the reason is the sintered substances has no enough activity.During the sintering of PcBN compacts with the binder TiN and Al,Al reactes with cBN and TiN and creates new compounds TiB₂ and AlN. cBN-TiN-Al compact's microhardness at 1200℃is higher than at 1300℃, but it's cutting life at 1200℃is not so good as at 1300℃, so the higher microhardness is not reflected the good characteristic.PcBN compacts sintered at about 1400℃with the binder AlN,Al is found in the AlN powders,and it has big influence to the experiment,but it is not found in the compact's XRD,so Al perhapse reactes with cBN and creates new compounds AlN,SEM showes the phenomena of AlNs reunite. PcBN's microhardness is the highest with the binder of AlN at about 1400℃,the way of increase temperature slowly and the way of increase temperature rapidly then holding the temperature have no serious different to the PcBN's microhardness . When do the cutting test, the compact's cutting life is higher with the way of increase temperature slowly than the way of increase temperature rapidly then holding the temperature.To sum up, The composite with the binder of TiN and Al has the highest cutting life at 1300℃in this paper.