The effect of thin film coatings and nitriding on the mechanical properties and wear resistance of tool steelud

摘要

The wear characteristics and mechanical properties of three different coatings deposited on different types of tool steel have been investigated. Four types of tool steels D2, D3, Vanadis 4 and Vanadis 10 were used as substrate materials. These materials were cut to the desired dimension 55mm x 25mm x 5mm and prepared for treatment and coating. The specimens were nitrided using gas nitriding, a case depth of 150 |im was achieved in all cases. Three types of coating TiC, TiN and AI2O3 were commercially deposited on the treated and untreated samples using the magnetron sputtering technique. A thin film coating of ~ 4|nm thickness was measured on each sample. The coatings were characterized in their thickness, hardness, adhesion and chemical composition. A wear test rig designed, constructed and commissioned at DCU was adapted for the wear tests. Wear characteristics of coated, nitrided, and prenitrided coated samples were investigated and compared to the uncoated samples characteristics. The microhardness of the surfaces coated and nitrided show an increase in hardness, with the highest hardness in the case of TiC coated Vanadis 10 samples. Wear test results show that titanium carbide coatings and nitriding treatment prove to have good wear resistance, on the other hand titanium nitride showed slight improve in wear resistance while alumina did not. Nitriding of the samples prior to the deposition of the coatings improved the wear resistance of the substrate materials particularly in the case of TiN and AI2O3 coatings. Adhesion evaluation of the coatings confirmed the observation of the wear and hardness. The substrate materials have a profound effect on the wear resistance and mechanical properties of the coated surfaces.