Titanium nitride ( TiN ) widely used as hard coating material, was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The study concentrated on cathodic arc physical vapor deposition (CAPVD), a technique used for the deposition of hard coatings for tooling applications, and which has many advantages. The main drawback of this technique, however, is the formation of macrodroplets (MDs) during deposition, resulting in films with rougher morphology. Various standard characterization techniques and equipment, such as electron microscopy, atomic force microscopy, hardness testing machine, scratch tester, and pin-on-disc machine, were used to analyze and quantify the following properties and parameters: surface morphology, thickness, hardness, adhesion, and coefficient of friction (COF) of the deposited coatings. Surface morphology revealed that the MDs produced during the etching stage, protruded through the TiN film, resulting in film with deteriorated surface features. Both coating thickness and indentation loads influenced the hardness of the deposited coatings. The coatings deposited on HSS exhibit better adhesion compared to those on D2 tool steel. Standard deviation indicates that the coating deposited with thickness around 6.7 μm showed the most stable trend of COF versus sliding distance.
Cathodic arc physical vapor deposition (CAPVD) a technique used for the deposition of hard coatings for tooling applications has many advantages. The main drawback of this technique is the formation of macrodroplets (MDs) during deposition resulting in films with rougher morphology. The MDs contamination and growth mechanisms was investigated in TiN coatings over high-speed steel, as a function of metal ion etching, substrate bias, and nitrogen gas flow rate; it was observed that the latter is the most important factor in controlling the size and number of the macrodroplets.
In the present study, the effect of various N 2 gas flow rates on friction coefficient and surface roughness of TiN -coated D2 tool steel was examined by a commercially available cathodic arc physical vapor deposition (CAPVD) technique. A Pin-on-Disc test was carried out to study the Coefficient of friction (COF) versus sliding distance. A surface roughness tester measured the surface roughness parameters. The minimum values for the COF and surface roughness were recorded at a N 2 gas flow rate of 200 sccm. The increase in the COF and surface roughness at a N 2 gas flow rate of 100 sccm was mainly attributed to an increase in both size and number of titanium particles, whereas the increase at 300 sccm was attributed to a larger number of growth defects generated during the coating process. These ideas make it possible to optimize the coating properties as a function of N 2 gas flow rate for specific applications, e.g. cutting tools for automobiles, aircraft, and various mechanical parts.
Titanium nitride ( TiN ) films were deposited on high-speed steel (HSS) using cathodic arc physical vapor deposition (CAPVD) technique. The effect of substrate bias on the crystallography, microstructure, deposition rate, coating thickness and composition, hardness, and adhesion strength of TiN films was investigated. The crystallography of the films was investigated using X-ray diffraction with glazing incidence angle technique. The coating microstructure and elemental composition analysis were carried out using field emission scanning electron microscopy (FE-SEM) together with energy-dispersive X-ray. Crystallography of the films revealed that the effect of substrate bias shows complex symmetry in crystal structure. The resputtering effect due to the high-energy ion bombardment on the film surface influenced the thickness as well as the color of deposited coatings. By increasing the substrate bias from 0 to - 150 V, the size and amount of macrodroplets decreased, whereas the micro-Vickers hardness decreased from 2530 HV0.05 to 1500 HV0.05. Scratch tester used to compare the critical loads for coatings and the adhesion achievable at substrate bias of - 50 V was demonstrated, with relevance to the various modes.
In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.
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