Influence of Xe Ion-Bombardment on the Substrate Microstructure and the Residual Stresses of Tin Coatings Deposited by Plasma Reactive Sputtering onto AISI 4140 Steel

Abstract

The seek for sustainability in the global economic scenario has led to the need for developing materials that provide higher productivity, greater speed of operation, extended lifetimes and enhanced surface finishing of engineering parts. To achieve these goals it is essential to modify the metal surface with respect to its behavior in situations of friction, wear and oxidation at high temperatures. In this work, we studied the impact of different surface treatment strategies involving atomic peening with Xe ions and low temperature plasma nitriding on the surface microstructure of AISI 4140steel and the consequences of those surface treatments on the residual stresses of TiN coatings deposited onto the pre-treated substrates. The results show that ion bombardment at 1000 eV leads to mainly sputtering of surface material and no appreciable surface activation could be obtained for the subsequent plasma nitriding treatment. In the sample subjected to simple plasma nitriding, the highest nitride content was found and a Ti-enriched transition zone deposition appears to build up during the coating deposition. Accordingly the residual stresses of the TiN coatings deposited onto the nitrided steel surface were significantly lower in comparison to those encountered in the coatings grown on the non-treated, only bombarded and bombarded followed by nitriding substrates.