Investigation of the boundary metallic substrate - ceramic coating obtained by detonation and VPS plasma spraying methods

摘要

Thermal sprayed coatings of metals and alloys are widely used for corrosion protection of surfaces, machine parts and construction elements, improvement of their wear resistance, formation of surface layers stable at high temperatures [1]. Existing methods of coating deposition such as flame, plasma, detonation and arc spraying methods allow coating forming from a very wide range of deposited materials practically on each substrate material. Despite of the fact of practical implementation of these methods one of the main factors that limit an application of thermal spray coatings is often an insufficient adhesion to the substrate [2, 3]. This problem is especially important in the case of the big difference in thermal expansion coefficients of coating and substrate materials. For example it is an actual problem for the ceramics based coatings that are used for enhancement of the thermal resistance of materials that are working under conditions of high temperatures and thermal shocks. It is considered that the following mechanisms are responsible for the bonding formation during the process of coating thermal spraying: mechanical anchoring of deformed splashed crystallized particles of coating on surface irregularities, factor of physical interaction (Van der Waals forces) and chemical interaction (metallurgical reactions, diffusion, new phases and compounds formation).