Influence of small amount of sintering additives on unlubricated sliding wear properties of SiC ceramics

• Published in: Ceramics international Vol. 37; no. 8; pp. 3599 - 3608
• Main Authors: Manoj Kumar, B.V., Kim, Young-Wook, Lim, Dae-Soon, Seo, Won-Seon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2011
• Subjects: Ceramics; Cleaning; Friction; Grain boundaries; Silicon carbide; Sintering; Sintering (powder metallurgy); Sintering additives; Sliding wear; Wear; Sliding wear; Sintering additives; Silicon carbide
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2011.06.018

Fully densified SiC ceramics were developed from commercially available β-SiC powders using small amount (3 wt%) of AlN–Sc 2O 3 or AlN–Y 2O 3 additives by hot pressing at 2050 °C for 6 h in nitrogen atmosphere, and their wear properties were investigated by subjecting to self-mated sliding at different loads (1, 6 and 13 N) under unlubricated conditions. SiC ceramics prepared with 3 wt% AlN–Y 2O 3 additives consisted of mostly large equi-axed grains with amorphous grain boundary phase of ∼1.2 nm thickness, whereas SiC ceramics sintered with 3 wt% AlN–Sc 2O 3 additives showed duplex microstructure of elongated and fine equi-axed grains with clean grain boundary. As the load was increased, the steady state coefficient of friction reduced from ∼0.6 to ∼0.2, and wear rate increased from 10 −6 to 10 −5 mm 3/N·m. It was observed that the friction did not depend on the additive composition, while less wear was observed for the SiC ceramics sintered with 3 wt% AlN–Sc 2O 3 additives consisting of clean grain boundary. The material loss was increased with the increased amount of sintering additive to 10 wt%. The worn surface morphology revealed that the material was primarily removed via surface grooving and microcracking at 1 N load, while tribochemical wear dominated at 6 and 13 N loads.