High-temperature glass-ceramic coatings to protect nickel alloys formed at near-operating temperatures

Compositions and manufacturing processes have been developed for heat-resistant coatings based on refractory glasses and modifying compounds to protect parts made of heat-resistant nickel alloys and corrosion-resistant steels against high-temperature gas corrosion during operation. A special feature of the developed coatings is the ability to form them in an oxidizing atmosphere under near-operational temperatures. The basis of the heat-resistant coating are refractory frits in BaO-Al2O3-SiO2 system, with the addition of silicon tetraboride SiB4 permitting to obtain coatings, the forming temperature of which is near to their operating temperature. Low density, availability of supply and low cost of raw materials, with relatively simple manufacturing process give these materials a competitive edge. The operational properties of this class of heat-resistant coatings are superior to those of their Russian and foreign-made counterparts, and its use seems promising in hot assemblies of liquid-propulsion jets and gas turbine engines. The developed heat-resistant coatings make it possible to provide an efficient protection of nickel alloys and corrosion-resistant steels against high-temperature gas corrosion and combustion at temperatures of up to 1 250 °C.