Mapping the micro-abrasion resistance of a Ni-based coating deposited by PTA on gray cast iron

Micro-scale abrasion was used to characterize abrasion resistance of a nickel-based hardfacing alloy deposited by Plasma Transferred Arc on gray cast iron using silica as abrasive agent. In order to investigate the occurrence of different abrasion mechanisms, several test conditions were used, namely: different silica abrasive contents and a range of normal loads and test durations. A scanning electron microscope (SEM) was used to study the morphologies of the spherical cup-shaped depressions induced by different test conditions. The results are discussed in terms of the effect of the dominant wear mechanisms on the abrasion resistance and the influence of the test conditions on the mechanism transition. The wear results lead to the conclusion that the specific wear rate essentially depends on the wear mechanisms (rolling or grooving) involved and not on the tests conditions employed, since these do not produce changes in the wear mechanism.