Determination of Adhesive and Cohesive Strength in Metal Coatings Deposited by Hypersonic Metallization

. It is known that at present, methods of thermal spraying are widely used to restore and strengthen various worn-out machine parts. As a rule, metal coatings applied by thermal spraying have lower strength characteristics than solid materials. It is believed that the strength of coatings is proportional to their adhesive and cohesive strength. The value of adhesive and cohesive strength depends on various factors, including the nature of the materials and the technology of coating. An important factor characterizing the possibility of using metal coatings in various industries is the strength of adhesion of coatings to the base metal. The paper presents the determination of the adhesive and cohesive strength of coatings from different materials, applied by the method of hypersonic metallization. The results of testing the strength of metal coatings made of ER316LSi-grade wire, nichrome (Cr20Ni80) and molybdenum wire are given in the paper. Based on the results of metallographic studies, the proportion of the participation of cohesive and adhesive components in the strength of coatings has been determined, and some features of coating destruction have been described. It has been found that the participation of the cohesive and adhesive components of the coating strength differs depending on the material used. The cohesive component prevails in the strength of coatings made of high-alloy wire of the ER316LSi-grade, at which destruction mainly occurs along the coating-base boundary. For nichrome coatings and especially for coatings made of molybdenum, the cohesive component is predominant, in which the destruction of the coating occurs not along the coating-base boundary, but between the coating layers.

Corrosion resistance of hypersonic metallization coatings sprayed

The study of the structural-phase state and anticorrosive properties in a 10 % aqueous solution of NaCl of hypersonic metallization coatings made of 08Mn2Si, 40Cr13, 09Cr19Ni9Ti steels, A199,3 aluminum and pseudo-alloys Fe—Al and Fe—Ni—Cr has been carried out. It has been established that hypersonic metallization coatings made of A199,3 aluminum and pseudo-alloys Fe—Al and Fe—Ni—Cr have the highest corrosion resistance. High corrosion resistance of the coating made of pseudo-alloy Fe—Al is achieved due to the enveloping of steel particles with aluminum during the spraying process, as well as due to the formation of a film of aluminum oxides on the surface of aluminum interlayers and aluminum-alloyed iron interlayers. High corrosion resistance of coatings made of high-chromium steels is due to their alloying with chromium and nickel.