Surface modification of AISI H13 steel by die-sinking electrical discharge machining and TiAlN coating: A promising hybrid technique to improve wear resistance

Abstract

Hybrid systems consisting of nitriding by die-sinking electrical discharge machining and subsequent titanium aluminum nitride (TiAlN) coating were produced on annealed AISI H13 steel aiming to study the conjugate friction and wear behavior for tribological applications. In this emerging nitriding process, urea [(NH2)2CO] was added to deionized water and used as dielectric fluid. The wear resistance and coefficient of friction of the produced systems were investigated against tungsten carbide (WC-12Co) pins. The sliding wear resistance of the hybrid systems produced by the new method were improved by fivefold compared to the only nitrided substrate. This behavior can be explained by the significant increase in hardness (fourfold compared to the nitrided substrate) and by reduction of the coefficient of friction. This can be attributed to the formation of new phases (Fe11N, TiN and TiO) and to the increased load bearing ability provided by the nitrided substrate. By EDM machining and simultaneously nitriding the work material in the as received state, it is possible to contribute to the productivity in the manufacture of dies and at the same time achieve the desired results, such as improving the wear resistance of the tool.