Study on friction characterization and wear-resistance properties of Si3N4 ceramic sliding against different high-temperature alloys

Ball-on-disc tests were performed to investigate the tribological behaviour of Si3N4 in contact with various high-temperature alloys, under dry sliding conditions, at different sliding speed, load and temperature. The tribological behaviour was characterized in terms of the friction coefficient and wear rate. The friction coefficient of Si3N4 sliding against high-temperature alloys was initially increased to a peak value and then decreased with the further increase of sliding speed. When Si3N4 slides against cobalt based high-temperature alloy (GH605) the friction coefficient and wear rate was the lowest. The smallest friction coefficient was attributed to the powder like wear debris and the formation of a tribo-layer on the worn surface of Si3N4 and GH605. The primary wear mechanism of Si3N4 sliding against iron and cobalt-based high-temperature alloy was adhesion, while a combination of abrasion and adhesion were considered to be the dominant wear mechanisms in the case of sliding against nickel-based high-temperature alloy at room temperature. At high temperature, the friction coefficient and wear rate were decreased with the increase of temperature. An oxide layer was found on the worn surface of Si3N4 after sliding against high-temperature alloys and the oxidative wear was considered to be the main wear mechanism. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.