A Theoretical Model for the True Hardness Determination of Ni-P / SiC Electroplated Composites

In this work we have applied a Hays –Kendall mathematical model to the Vickers microhardness values to eliminate the troublesome indentation size effect (load dependence of hardness) and obtain a unique value representing the true hardness for each coating. Examination of the unique hardness values has been possible in conditions of heat treatment at 190 0C and 420 0C. Key words: Hays –Kendall model, Ni-P/SiC coatings, hardness, ISE effect, heat treatment The hardness of Ni-P alloy increases by reinforcing of the Ni matrix with SiC particles. Another possibility for a hardness increase is obtained by applying heat treatments to the Ni-P/Si-C composites coatings [1, 2]. Due to the small thickness of the coatings ranging from 24 to 38 µm very small loads in the range 15-300g have been applied on the indenter when the Vickers microhardness was measured. Such small loads have been selected for producing penetration depths small enough to avoid any influence from the mild steel support on which the coatings were