WEAR BEHAVIOR OF AL2O3, SI3N4 AND CBN CUTTING-TOOL MATERIALS AT HIGH SLIDING SPEED

Tool materials based on Al2O3, Si3N4 and CBN were tested on a pin-on-disk wear machine with an AISI 4041 steel counterface under low pressure (0.25 MPa) and at high sliding speed ranging from 10 m/s to 50 m/s. The humidity of the laboratory was controlled at 50 percent during the wear tests. It was found that the wear rate of CBN was the smallest among the materials at all speeds tested. The wear rate of Si3N4 decreased from 7 x 10(-7) mm3/N M to 2 x 10(-7) mm3/N. m when the speed increased from 10 m/s to 30 m/s. It then increased to 6.3 x 10(-7) mm3/N.m at 50 m/s. The wear rate of the ZrO2 reinforced Al2O3 was quite high (1.5 x 10(-6) mm3/N.m) at 10 m/s, which was more than twice that of SiC whisker-reinforced Al2O3 and other alumina ceramics tested in previous studies. The difference of the wear resistance between the two Al2O3 based materials should be due to the additional phases of ZrO2 and SiC whiskers. The wear results have been compared with those of milling tests with the same counterface at a speed included in the investigated range on the pin-on-disk tribometer. A correlation was found between the wear results and the tool life in the milling test for CBN, Si3N4, and SiC whisker-reinforced Al2O3.