Influence of substrate temperature and gas pressure on aluminum oxynitride coatings obtained by pulsed laser deposition

The paper presents results of the investigation on the influence of deposition parameters, such as substrate temperature, total gas pressure and reactive gas composition on the structure, chemical composition and mechanical properties of aluminum oxynitride coatings obtained by pulsed laser deposition (PLD) method. Selection of process parameter ranges, which could be promising for aluminum oxynitride (ALON) coatings deposition, was the main objective of the work. Two series of experiments were carried out with varied pressure and temperature. It was found that from the chemical composition viewpoint, the most promising are atmospheres containing 20 % to 40 % oxygen. The nitrogen to oxygen ratios in the coatings can be controlled by increasing the total pressure or substrate temperature. However, increasing the pressure has a negative effect on the O + N:Al ratio, mechanical properties and quality of the coatings. The influence of temperature is much less drastic and more controllable. Increasing the deposition temperature is much more beneficial since it improves the mechanical properties and can compensate to some extent the negative effect of the total pressure. From the coating quality viewpoint, it is possible to establish an optimum temperature range for which the coatings are characterized by a compact structure and a limited number of droplets.