Gladkiy Ya.N., Lisovoy E.N. Wear-resistant FeAl2-Ti-Si detonation spray coatings under friction loading at elevated temperatures.

Abstract

Performing working and operating functions at elevated temperatures is inherent in most of mating and moving machinery parts which operate under friction. In disclosing interrelations between tribological properties of materials, their structure, effect of outside factors, which determine a friction system reliability, the state-of-art physicochemical analysis techniques have been employed. This allowed the investigation of friction and wear behavior of FeAl2-Ti-Si detonation coatings developed (using domestically available resources) to protect machinery components operating under high temperature friction. An optimal content of components corresponding to the maximal coating wear resistance has been found in the process, their physicomechanical properties examined. The structure-phase composition has been defined thus enabling the composition of the coatings to be categorized as a structure of fine conglomerate of strengthening phases. It has been established that coating wear resistance in the regime of a structural adaptability is due to the stable formation of thin-film structures of oxide type as a result of the cooperating areal tribochemical effects. The quantitative changes of microhardness in oxide structures of both simple and complex compositions minimizing the destruction of surface layer under high temperature friction have been obtained. It has been demonstrated that the presence of oxide films of β-tialite (Al2TiO5), mulite (Al2SíO5), silicates of FeSiO4 type, and others on friction surfaces opposes the adhesive-molecular interaction of working surfaces, acting as a solid lubricant, and is beneficial for accommodating a grain-boundary glide. The process-dependent parameters of sputtering have been optimized. Thus, the efficient ratios of working gases and extents of barrel filling have been found, making it possible not only to implement the predicted chemical composition but to obtain the set structure enabling the minimal friction factors to be provided under the given test conditions. The FeAl2-Ti-Si composition coatings not containing scarce and costly components have been developed for the purpose of enhancing the wear resistance of tribological units which, as proved by the test findings, provide their production safety to suit the requirements and opportunities to be offered by developing a new competitive material for wear resistant coatings fabricated through the detonation spraying technique.