Scratch Test and Adhesion Properties of Titanium Coatings Deposited by TIG Welding on Steels

Abstract

Scratch test is one of widely used, fast, and effective methods to obtain the critical loads that are related to adhesion properties of coatings. The determination of adhesion and the scratch resistance is essential for the mechanical characterization of surface layers for research and industry. To evaluate the performance of coatings the scratch test with a Rockwell-C diamond stylus as indenter is a commonly used test for the characterization of hard coatings on predominant metallic substrates due to its comparatively robust experimental setup, the easy use and the representative results. This is the only technique capable of imaging such interface defects which are due to the stressin duced by the scratch experiment.This paper aims to characterize the adhesion and scratch resistance using Millennium200 - Technical Tribo equipment of Ti layer deposited on steel surfaces by means of TIG/WIG welding technique. Ensuring appropriate functional properties of WIG welding coatings (Ti) requires a good compatibility with the substrate material (S235). For this reason was used to deposit titanium WIG welding an intermediary layer of copper, obtained in the same experimental conditions. The optimal selection of the coating material takes into consideration the metallurgical, mechanical and process technology compatibility. The mechanical properties of coatings must match the substrate. From this point of view, maintaining a high corrosion resistance is mainly conditioned by achieving a good adhesion and a microstructure free of internal cracks or other defects.