Study On Diffusion Between Ceramic Tools And Stainless Steel

When ceramic tools cut hard materials, especially in dry cutting, the thermal is easy to accumulate near the edge of ceramic tools owing to its low thermal conductivity. The thermal energy can provide activation energy for elements diffusion, which is possible to make elements diffusion between ceramic tools and the difficult processed materials couple. Because of this, ceramic tool will reduce cutting performance. Through theory analysis and experiment research, this paper studied the elements diffusion process between ceramic tools and difficult-to-machine material, 301 stainless steel, systemically investigated the laws of diffusion and the influence of cutting tools performance on element diffusion. The aim of this paper is to prolong the life of ceramic tools and to provide theory for designing new ceramic tools.Expression of element diffusion concentration that adapt to ceramic tools and 301 stainless steel was calculated through Fick's second laws of diffusion analysis. Through further calculate, we simulated the diffusion rules on the element Ti which is in ceramic tools and the element Fe which is in 301 stainless steel. It provided foundation of theory for analyzing diffusion experiments. Microscopic mechanism in element diffusion between ceramic tools and 301 stainless steel has been observed and discussed.Two ceramic tools of Al₂O₃/TiC and Si₃N₄/TiC, both of which had been toughened by TiC were chosen for element diffusion experiment with 301 stainless steel. Through experiments, the diffusion of Ti and Fe was comprehensively analyzed, and the connection of temperature and time with diffusion effect between ceramic tools material and 301 stainless steel was reviewed systemically. The analysis showed that the diffusion degree of Al₂O₃/TiC with 301 was serious than Si₃N₄/TiC with 301 under the same high temperature and keeping-temperature time; diffusion temperature has more effect on diffusion than time. To same diffusion degree, the higher diffusion temperature is, the shorter time needs. According to the result of experiments, we should take same actions for decrease the diffusion wear of cutting tools: the first is to reduce the cutting temperature; the second is better to finish cutting process before the initiative time of accelerating diffusion.Tool hardness was tested after diffusion experiment. It is showed that tool hardness of materials had diffused obviously changed. Hardness near the diffusion interface greatly decreased, and hardness far away from the interface got to a normal level gradually. But the hardness of workpiece near diffusion interface was obviously higher than its normal hardness, and gradually decreased to normal hardness far away diffusion interface. Although it is only dozen microns took place between ceramic tool materials and 301 stainless steel, the effect caused by diffusion was more than the distance of elements diffusion.