Microwave processing of sprayed alumina composite for enhanced performance

To meet the challenging in-service requirements, surfaces of many mechanical components need to be modified. This can be achieved by altering the surface properties through deposition technique followed by suitable post processing. Apart from the conventional methods, laser treatment is the most popular post processing technique. Of late, microwave heating is emerging as one of the potential post processing sources. Microwave processing of materials is fundamentally different from traditional techniques. In microwave processing, energy is directly transferred to the material through interaction of electromagnetic waves with molecules leading to volumetric heating. However, for processing of transparent (to microwaves) materials, a technique known as microwave hybrid heating (MHH) can be used. In this study, MHH is used for post processing of plasma deposited alumina-titania ceramic composite coatings on steel substrate; resulting properties of the post processed coatings are evaluated. Results show reduction in porosity, enhancement in microhardness, and wear resistance of the irradiated coatings owing to microstructural changes and densification. Results are discussed with suitable illustrations. (C) 2002 Elsevier Science Ltd. All rights reserved.