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Is Glass Infiltration Beneficial to Improve Fretting Wear Properties for Alumina?
Author(s) -
Sarkar Debasish,
Basu Bikramjit,
Chu Min Cheol,
Cho Seong Jai
Publication year - 2007
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.1551-2916.2006.01380.x
Subject(s) - fretting , materials science , borosilicate glass , tribology , composite material , coefficient of friction , glaze , infiltration (hvac) , profilometer , fretting wear , thermal expansion , metallurgy , surface roughness , ceramic
In this article, we report the tribological properties of the glass‐infiltrated (GI) alumina with a major aim to understand scientifically the influence of glass infiltration on the underlying mechanisms of material removal (when fretted against steel). For this purpose, the test samples were fabricated by infiltrating molten borosilicate glass on a sintered alumina. Thermal expansion coefficient mismatch of two phases (3.5 × 10 −6 °C −1 for glass and 9 × 10 −6 °C −1 for alumina) causes residual compressive stresses, which assists in the enhancement of mechanical properties. Systematic fretting wear experiments were performed on as‐sintered Al 2 O 3 and GI alumina surface against bearing steel under dry‐unlubricated conditions at varying load (2 N, 5 N, and 10 N) with different fretting durations (10 000, 50 000, and 100 000 cycles). Relatively less variation in steady state COF (0.5–0.6) was measured for both the as‐sintered Al 2 O 3 and GI Al 2 O 3 under the varying operating conditions. Laser surface profilometer analysis indicates that better wear resistance could be obtained for GI alumina at lower load (2 N) after 100 000 fretting cycles (7.5 × 10 −6 mm 3 /N·m), in comparison with the bare or virgin alumina surface (1.1 × 10 −5 mm 3 /N·m). Also, the wear rate decreases with an increase in load to 5 N and 10 N, with the lowest value of 1.5 × 10 −6 mm 3 /N ·m measured after fretting at 10 N load. Importantly, no noticeable difference in wear rate between as‐sintered and GI alumina could be measured at a higher load (5 N, 10 N). Atomic force microscopy and X‐ray diffraction analysis of wear debris illustrate that an amorphous tribolayer and finer debris particles, with composition of Fe(OH) 3 and/or Fe 2 SiO 4 , adhere to the worn surface. The formation of triboreaction products has been explained using thermodynamically feasible reactions. The major wear mechanisms depend on the applied load and are being identified as fatigue wear, three‐body abrasion, and formation of a tribochemical layer.