New type AlMo-, AlTi- or Si-based magnetron sputtered protective coatings on metallic substrates

Three different types of refractory protective coatings deposited by means of reactive and/or non-reactive magnetron sputtering have been developed in the Technical University of Lodz in cooperation with the Academy of Mining and Metallurgy in Cracow: metallic AlMo- and AlTi- or covalent-bonded Si-based coatings. The first one consists of the outer AlMo(Si) layer and a particular (TiC/TiN) × 20 intermediate diffusion barrier multilayer coating protecting the outer layer against the mutual diffusion process at high temperature between the outer layer and the ferrous substrate. The complex nanocrystalline refractory coatings with the diffusion barrier protected the heat- and creep-resistant high chromium AISI 430 ferritic steel substrate against the oxygen and/or sulphur vapours up to the temperatures as high as 1023 K. Another series of amorphous coatings based on Si covalent compounds (Si x C y , Si x C y N z and Si x N y ) deposited on the same AISI 430 steel protected the substrate against the oxidation up to the temperature 1173 K. At the same time, the coatings protected the steel substrate against electrochemical corrosion as well as against the chemical one even in most aggressive acidic or basic solutions up to the temperature as high as 350 K. The heat- and creep-resistant intermetallic γ-TiAl substrates have been deposited with nanocrystalline γ-TiAl-based coatings microalloyed with Cr atoms. The deposits have imparted to the γ-TiAl substrate a very good oxidation resistance up to the temperature as high as 1173 K: the oxidation rate of the coated specimens was at least two orders of magnitude smaller than that for the uncoated ones. The newly developed protective coatings can find a broad range of applications, as, e.g. in power industry, ferrous- and non-ferrous metallurgy, mining, aviation, car and ship industry, chemical processing of carbon, petrochemistry, waste treatment and recycling, microelectronics, MEMS, etc.