β-SI3N4 cutting tools obtaining for machining of the gray cast iron

Abstract

Recentely, Si3N4 has been used as cutting tools in several alloys machining. Such materials shows SiAlONs and β-Si3N4, that it has excellent thermomachanical properties. This work had as objetive to develop and to apply β-Si3N4 cutting tools in machining of gray cast iron, starting from a mixture composed by 78.30 wt % α-Si3N4, 1.00 wt % A12O3, 14.40 wt % A1N, 3.15 wt % CeO2 and 3.15 wt % Y2O3, that was pressed and sintered at 1900°C. After characterization, cutting tools showed, HV = 20.50 GPa, KIC = 6.45 MPa.m1/2, with 95 % β-Si3N4 phase. Then, it were submited to machining of gray cast iron using: 1a step - Vc=180, 240, 300 and 360 m/min, f = 0.12mm/rot and ap = 1.00 mm; and 2a step — Vc = 300m/min, f = 0.23, 0.33 and 0.40 mm/rot and ap = 1.00 mm. For 7500 m cutting length, results showed excellent performace.