Effect of different pretreatment parameters on silicon nitride substrate surface roughness prior to diamond deposition

Abstract

High hardness, high strength to weight ratio, wear resistance, and low coefficient of thermal expansion properties have made silicon nitride ceramic to be one of the most applicable engineering materials for many applications including structural applications, military, refractory, energy production, automotive and aerospace, and even biomechanical applications. These beneficial properties also attract many researchers to conduct studies on this advanced ceramic for several decades. One of them is surface pretreatment prior to diamond coating. This project presents the effect of pretreatment parameters on silicon nitride substrate prior to diamond deposition. Full factorial experimental design is used to plan and analyze the experimental trials. Two factors studied are chemical etchant concentration and etching time. Results from the experiments show that etchant concentrations and etching time play a significant role on substrate surface roughness. Empirical models which represent the relationship between chemical etching and surface roughness have successfully developed within acceptable accuracy. The confirmation tests show that surface roughness values are in between the predicted intervals.