Synthesis of hard TiN coatings with suppressed columnar growth and reduced stress

Abstract

Titanium nitride normally grows with a columnar grain structure. In this study, we prepared TiN/CNx multilayered coatings with the intent of using the CNx layers to interrupt the grain growth of TiN to attain an equiaxed grain structure. The TiN/CNx coatings were synthesized by direct current magnetron sputtering. Our investigations showed that three important process conditions are required to obtain superhard and smooth TiN/CNx coatings with low internal stress: (i) a TiN buffer layer with strong (111) texture; (ii) proper bias during the growth of the TiN buffer and TiN/CNx coating; and (iii) small thickness for the CNx layers.