SYNTHESIS AND CHARACTERIZATION OF TITANIUM BASED HARD COATINGS

Abstract

Hard coatings have been successfully used for protection of materials and particularly to enhance the life of cutting tools since the 1970's and it is defined by its hardness which is the measure of resistance to plastic deformation. Hard coatings are extensively used for tribological applications and their development by various physical and chemical deposition techniques are ever growing to achieve their superior performance in the actual engineering applications such as to increase the lifetime of cutting and forming tools under dry and high speed machining conditions and the protective coatings for turbine blades and engine parts to improve their durability. Therefore, by properly selecting the coating techniques and materials, we can protect not only the substrate materials to prolong their service life, but also increase commercial value of the products. Hard coatings of binary and ternary metal nitride materials are used in various engineering applications due to their remarkable physical and mechanical properties including high hardness, high melting point, chemical inertness, and good thermodynamic stability. The control of the microstructural characteristics in terms of grain size, crystallographic orientation, lattice defects, texture and surface morphology as well as phase composition and surface morphological evolution of transition metal nitride films are very important in realizing the aforementioned properties so as to extend the performance and life time of the coated products. The literature on the optimized process variables using sputtering techniques for the deposition of transition metal nitride films with the desirable microstructural characteristics is very limited.