The goal of this study is to characterise the mechanical properties of zinc and manganese phosphate coatings before and after running in. The characterization is done with nano-indentation to determine the individual crystal hardness and single asperity scratch tests to investigate the deformation behaviour at the single asperity level. The nano-indentation and scratch tests reveal brittle deformation behaviour for the as received coatings. Under uni-directional sliding both layers reduce to a powder which is subsequently compacted to a so called glaze layer. The smooth and brittle glaze layer has a higher hardness compared to the as received coating and its properties can be satisfactorily described by models normally used for a hard coating on a soft substrate.
- Mechanical characterization
- Phosphate conversion coatings
- Scratch test