This work evaluates the influence of yttrium on the heat and wear resistance of active arc sprayed (AAS) coatings produced using FeCrBAl cored wire. The AAS process differs from ordinary arc spraying in that it uses propane-air combustion products as a carrier gas instead of compressed air. This increases particle velocity and temperature and forms a reducing atmosphere that protects metal particles in flight and improves coating adhesion and porosity. Coating samples produced with different amounts of yttrium were characterized in terms of surface morphology, microstructure, phase composition, and hardness. They were also subjected to heat resistance, abrasive wear, and corrosion tests in which they performed better than typical wrought steels used in boilers.

The thermal cycle test of Al 2 O 3 sprayed 1%Cr-0.5%Mo steel and 18%Cr-8%Ni steel was performed, and the failure type of thermally sprayed coating on both steels was compared. The results obtained are follows. (1)The thermal cycle fatigue life of thermal sprayed 1%Cr- 0.5%Mo steel was shorter than that of thermal sprayed 18%Cr-8%Ni steel. (2)In the case of thermally sprayed 18%Cr-8%Ni steel that is difficult to oxidize at high temperature, during thermal cycle, a tensile stress occurs in a sprayed coating and a compressive stress occurs in a substrate. Thus the thermal strain occurs at the interface of sprayed coating and substrate. The sprayed coating delaminates when the thermal cycles reach the limit value. (3)In the case of thermal sprayed 1%Cr-0.5%Mo steel that is easy to oxidize at high temperature, during thermally cycle, dense oxide film forms at the interface between the sprayed coating and substrate, and adhesive strength in the interface becomes low. Thus the sprayed coating delaminates under the lower thermal strain.

The given article presents some results of the scientific research devoted to the development of a new class of scale-resistant powder materials of the Si-Ti-Mo-B system for thermal spraying and using these materials for the creation of heat-resistant coatings on the niobium base alloys by means of various methods of thermal spraying. Also under consideration are problems relating to the theory and practice of obtaining reliable protective coatings on high-melting metals and their alloys, niobium ones included, intended for operation in high-enthalpy oxygen-containing gas flows. Hazard in commencing an oxidation reaction of the base material under coating is connected with density of open pores and cracks, and partial pressure of the oxidizer. Powdered multicomponent heterophase materials for gas-thermal spraying of protective coating with a self-healing ability and controlled properties are proposed. Finally the results of some properties of new silicide-type heterophase powders containing silicide and boride phases for a thermal spraying process and some properties of protective coating deposited on the niobium base alloys by means of a thermal spraying technique are presented.

Thermal sprayed coatings of polypenylene-sulphide (PPS) and polyphenyletherether-ketone (PEEK) have been produced by HVAF spray system. The properties of these coatings have been investigated by corrosion test and FT-IR analysis. The main results of this study are summarized as follows; (1) In case of PPS coatings, PPS powder is oxidized during thermal spraying. However, PPS coatings have a good corrosion resistance. However, PEEK coatings have high porosity so that corrosion of the substrate occurs. (2) In case of PEEK coatings, the molecular structure of PEEK powder is not changed during thermal spraying.