Tribological properties of spark-plasma-sintered ZrO2(Y2O3)-CaF2-Ag composites at elevated temperatures

• Published in: Wear Vol. 258; no. 9; pp. 1444 - 1454
• Main Authors: OUYANG, J. H, SASAKI, S, MURAKAMI, T, UMEDA, K
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier Science 01-04-2005; Amsterdam; New York, NY
• Subjects: Applied sciences; Exact sciences and technology; Friction, wear, lubrication; Machine components; Mechanical engineering. Machine design; Solid lubricant; Friction and wear; High temperature; Oxide ceramics; Composite material; Dry friction; Self-lubricating composite; Lubricating film; Zirconia; ZrO2(Y2O3) ceramics; Zirconium oxide; Solid lubricants; Lubricant additive; Sintering; Content; Wear; Yttrium oxide; Alumina; Self lubricating material; Sliding friction; Room temperature; Tribology; Lubrication mechanism
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2004.10.007

Spark-plasma sintering is employed to synthesize self-lubricating ZrO2(Y2O3) matrix composites with different additives of CaF2 and Ag as solid lubricants by tailoring the composition and by adjusting the sintering temperature. The friction and wear behavior of ZrO2(Y2O3) matrix composites have been investigated in dry sliding against an alumina ball from room temperature to 800DGC. The effective self-lubrication at different temperatures depends mainly on the content of various solid lubricants in the composites. The addition of 35 wt.% Ag and 30 wt.% CaF2 in the ZrO2(Y2O3) matrix can promote the formation of a well-covered lubricating film, and effectively reduce the friction and wear over the entire temperature range studied. The friction coefficients at low temperatures were at a minimum value for the composite containing 35 wt.% of silver. At this silver concentration, low and intermediate temperature lubricating properties are greatly improved without affecting high-temperature lubrication by the calcium fluoride in ZrO2(Y2O3) matrix composites. The worn surfaces and transfer films formed during wear process have been characterized to identify the synergistic lubrication behavior of CaF2 and Ag lubricants at different temperatures.