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Tribological Characteristics of α‐Alumina at Elevated Temperatures
Author(s) -
Dong X.,
Jahanmir Said,
Hsu Stephen M.
Publication year - 1991
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1991.tb04340.x
Subject(s) - tribology , materials science , wear coefficient , composite material , coefficient of friction , friction coefficient , diffusion , metallurgy , thermodynamics , physics
The tribological characteristics of a high‐purity α‐alumina sliding on a similar material under unlubricated conditions are divided into four distinct regimes. At low temperatures, T < 200°C, tribochemical reactions between the alumina surface and water vapor in the environment control the tribological performance. The coefficient of friction in this temperature range is approximately 0.40 and the wear coefficient is less than 10 −6 , independent of contact load. At intermediate temperatures, 200°C < T < 800°C, the wear behavior depends on the contact load. At low loads, wear occurs by plastic flow and plowing; the coefficient of friction is approximately 0.60 and the wear coefficient is less than 10 −6 . At loads larger than a threshold value, severe wear occurs by intergranular fracture. The coefficient of friction increases to 0.85 and the wear coefficient increases to a value greater than 10 −4 . At temperatures above 800°C, formation of a silicon‐rich layer on the wear track by diffusion and viscous flow of the grain‐boundary phase reduces the coefficient of friction to 0.40, and the wear coefficient is reduced to a value less than 10 −6 . The results of the wear tests and observations of the fundamental mechanisms controlling the tribological behavior of this material are consolidated in a simple wear transition diagram.