The Cutting Experiment And Wear Mechanism Of Nano-modified Al₂O₃-TiB₂-CaF₂ Self-lubricating Ceramic Tools

Adding a certain amount of calcium fluoride into the ceramic tool material can make ceramic cutting tools perform lubrication properties in dry cutting.But the addition of calcium fluoride into the ceramic material will reduce the mechanical strength of the tool material,this study attempts to add nano calcium fluoride into the Al₂O₃-TiB₂ based ceramic material by nanocomposite toughening effect to make up for the impact of adding calcium fluoride into the ceramic tool materials on the mechanical strength of material.Based on the previous studies,the cutting performance and wear mechanism of Al₂O₃-TiB₂-CaF₂ nano-modified self-lubricating ceramic cutting tools were studied.?1?The nano-modified self-lubricating Ceramic Tools,ATF1,ATF5,ATF10,whose CaF₂ volume fraction of 1%,5% and 10%,were prepared.The observation showed that the addition of nano calcium fluoride can toughen matrix material to a certain extent,but still make the strength of self-lubricating mechanical ceramic material decreases.?2?With ATF1,ATF5,ATF10,the cutting experiments of 45 and 40 Cr steel were carried out.During the experiments,the kistler dynamometer was used to measure the cutting forces during cutting process,and the FLIR infrared cameras was used to measure the temperature of the bottom of the chip on rake face to measure the cutting temperature approximatily.?3?With ATF1,ATF5,ATF10,the cutting tests of 45 steel were carried out.ATF1 had the maximum amount of material removal,and best performance,which mainly due to the high mechanical strength of the material caused by its lower content of CaF₂.When the cutting speed and depth of cut in the same conditions,ATF5 cutting performance had better cutting performance,compared with ATF10.Although the strength and hardness of ATF5 is lower than ATF10,the lack of coordination between thermal expansion coefficients of the components accelerated tool wear of ATF10 under high temperature conditions,because its high CaF₂ content of ATF10 and the big difference in thermal expansion coefficient between CaF₂ and matrix material.?4?With ATF1,ATF5,ATF10,the cutting test of 40 Cr were carried out.Because of its lower CaF₂ content,ATF1 had the highest hardness and strength,and performed well in cutting process.ATF5 had the worst performance in the cutting test of 40 Cr.The rapid wear of ATF5 was mainly because of its low hardness and strength,and high tensile strength of 40 Cr steel.ATF10 had a better cutting performance in the cutting tests of 40 Cr,and from the EDS energy spectrum of tool flank,it can be seen that,there is a clear enrichment and displacement phenomenon of CaF₂ on the wear areas of tool flank.?5?In the cutting test of 40 Cr using ATF10,the increasing trend of cutting temperature which increases with the increase of cutting power was slowly.This is because,there is a clear CaF₂ self-lubricating film on the wear areas of ATF10 tools,the appearance of self-lubricating film reduced the friction between the bottom of the chip and rake face,reducing the temperature of the bottom of the chip.?6?The cutting temperature had a large influence on the formation of self-lubricating film on nano CaF₂ self-lubricating tool.Compared with the cutting tests of 40 Cr steel,the cutting temperature is higher in the cutting tests of 45 steel,which leads no obvious lubricating film appeared on the wear region of cutting tool in the cutting tests of 45 steel using ATF10,tool weared faster.While,there is a clear lubricating film forming on wear area of the tools in the cutting test of 40 Cr steel using ATF10.