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最近,日本东芝坦葛洛伊公司与日铁超硬工具公司,共同开发了新型涂层刀片,并已投放市场。该刀片在断续切削与重切削中显示出特别优异的性能。采用CVD(化学气相沉积)法在超硬含金表面上涂覆TiC、TiCN、TiN、Al_2O_3、等陶瓷膜,可显著提高刀片耐摩性。但是,这种涂覆处理,虽提高刀片的耐摩性,却降低了切削时的耐缺损性。据研究,CVD涂覆处理的刀具,耐缺损性的指标——抗折力降低到母材的45％-55％。因此,涂层刀片在继续切削与重切削时,效果并不令人满意。究其原因,是由于作为涂层的陶瓷的热膨胀系数,比超硬合金母材大,高温涂覆后,在冷却过程中,涂层比母材的收缩量大,涂层中产生残余拉伸应力,残余应力在断续切削或者任何一种应力负荷作用时,都会促进裂纹的发展。
Recently, TOSHIBA TOSHIO LOYALTY Co., Ltd. of Japan and Nippon Steel Superhard Tools Co., Ltd. jointly developed a new coated blade, and has been on the market. The blade shows exceptionally good performance in interrupted cutting and heavy cutting. The CVD (chemical vapor deposition) method is used to coat TiC, TiCN, TiN, Al_2O_3, and other ceramic films on the surface of the super-hard gold-containing alloy to significantly improve the wear resistance of the blade. However, this coating treatment, while improving the wear resistance of the blade, reduces the cutting resistance at the time of cutting. According to the research, the tool of CVD coating treatment, the index of the defect resistance - the bending strength is reduced to 45% -55% of the base metal. Therefore, the coated blade continued cutting and heavy cutting, the effect is not satisfactory. The reason is due to the coefficient of thermal expansion of the ceramic as a coating being larger than that of the cemented carbide base material. After the coating at a high temperature, the amount of shrinkage of the coating layer over the base metal during the cooling process is large, and residual stretching occurs in the coating Stress, residual stress in the intermittent cutting or any kind of stress load, will promote the development of cracks.