The Microstructure and Wear Resistance of the Ti-assisted Hot Plasma Nitrided Layer

Abstract

In order to improve the wear resistance of the surface nitrided layer of 1060 aluminum matrix, the nitrogen containing thermal plasma Ti-assisted nitriding method was adopted to obtain the strengthening phases of AlN and TiN simultaneously. The influence of the nitriding technological parameter on Ti-assisted nitriding was studied through changing the nitrogen containing thermal plasma current (I = 100 to 160 A) and the flow ratio of the nitriding atmosphere (Ar/N₂ = 8/2, 6/4, 4/6 and 2/8 L/min). The nitrided layer prepared under the Ti-assisted nitriding conditions was composed of AlN and Al solid solution, Al₃Ti and TiN phases. The average microhardness of TiN dense distribution area was 1025 HV_0.1, significantly higher than that of AlN dense distribution area (589 HV_0.1). When the proportion of nitrogen in the plasma gas was 40% and the current was 120 A, the weight loss of the nitrided layer after wear was 3.4 mg, and its average friction coefficient was 0.214. Compared with those of aluminum matrix, the friction coefficient of the surface nitrided layer reduced by 33 %, and the wear resistance capacity increased by 4.5 times. Ti-assisted nitriding could obtain the AlN and TiN compound strengthening effect, so as to improve the wear resistance of the nitrided layer significantly.