Cored Fe-Cr-Al wires for arc metallization of heat-resistant coatings

To monitor the homogeneity of powered wires the angle of repose and its coefficient of flow ability were defined. It has been established that a burden of special composition obtained by limiting the amount of coarse and fine fractions in comparison with the standard burden having initial granulation has a smaller angle of repose and higher flow ability, providing uniformity in particle size and chemical composition and improving coating quality. The influence of additional alloy building of wires with titanium, silicon and yttrium on heat resistance was studied by thermogravimetric analysis and scanning electron microscopy. It was defined that the introduction of titanium and silicon prevents the formation of carbide (Fe, Cr)7C3, aluminum nitride AlN and high temperature corrosion for both base alloy Fe-Cr-Al and for spraying coatings and the introduction of yttrium prevents the segregation of sulfur at the border due to the formation of sulfides Y2S3. For spraying coatings the same effects are achieved by the introduction of the wires of high amounts of titanium and silicon into the burden, which is associated with the conditions of their formation in arc spraying. On the basis of the established principles the powered wires of alloying system Fe-Cr-Al-Ti-Si were developed to be used as spraying coatings. Spraying coatings developed have the heat resistance equal to that of austenitic steels and much higher than that of ferrite-pearlite, ferrite-martensite steels that are widely used in boiler construction.