Characterizations of Composite Titanium Nitride Coatings Deposited by Very Low-Pressure Plasma Spraying

In this study, composite titanium nitride coating deposition by reactive spraying was carried under a controlled low-pressure (150 pa) atmosphere with a F4-VB low-power plasma gun. Pure titanium powder is injected into the plasma, and a reactive gas (N2) is added on the substrate surface to generate nitriding reactions. The experiments were carried out at different radial distances of the plasma plume. Morphologies of the coating present quite dense binary structure deposited by molten, vapors particles. As measured by means of x-ray diffraction, the coatings composition is modified with an evolution of TiN0.3, Ti2N and TiN phase crystalline phases along radial distance of the plume. The nitride phases (Ti2N, TiN) contents of the coating show a linear relationship with the micro-hardness of the coating. Micro-hardness of VLPPS-processed composite titanium coatings reaches 1071HV0.03.