Fatigue Evaluation of Novel HVOF Spray Coated Al Bearing Alloys
M.C. Mwanza, M.S. Ali, S. Syngellakis
MATERIALS FORUM
Abstract
The high velocity oxy fuel (HVOF) lining shows superior fatigue resistance to conventional roll-bonded (RB) linings of similar composition when compared in terms of local strain ranges experienced in the coatings. In terms of fatigue resistance of the bearing system, our simplified fatigue testing approach indicates that the HVOF coated system shows worse fatigue resistance, due to reduced constraint from the softer steel backing produced by the HVOF process (no work hardening of the steel occurs as it does during roll- bonding). The complex mechanics of the layered system are sensitive to bearing architecture (e.g. relative layer thicknesses) as well as the constituent materials properties. The improved fatigue resistance shown by the HVOF lining has been linked to the very much finer Sn distribution improving fatigue initiation resistance compared with the RB lining, although short crack growth rates are somewhat worse.
Keywords:HVOF/roll-bonded coatings; Fatigue; Crack growth; Bearings; Initiation; Al-Sn alloys; lifetimes
|
