ВПЛИВ СУПУТНЬОГО ОБТИСКАЮЧОГО ПОТОКУ ПОВІТРЯ НА СТРУКТУРУ І ВЛАСТИВОСТІ ПОКРИТТЯ ПРИ ПЛАЗМОВО- ДУГОВОМУ НАПИЛЮВАННІ ПЛАВКИМ СТРУМОПРОВІДНИМ ДРОТОМ.

The paper is devoted to studying the technological features of plasma-arc spraying by consumable current-conducting wire-anode. The relevance of applying such a process is related to the possibility of spraying directly by atomization of wires without the need to make powders from them. Experimental verification of the results of mathematical prediction of the influence of annular protective flow of compressed air, accompanying the particle-loaded plasma jet, on the results of plasma-arc spraying by compact wire anodes was performed. The key role of increasing this flow rate above 20 m³/h for improvement of the spay-deposited coating formation and quality was established. In spraying of coatings from compact wires porosity decreased with increase of the values of flow rates of accompanying air flow G2, and achievement of this parameter values within 0.5…2.5 %. Conducted experiments allow producing porefree coatings in spraying with wires from М2 copper, Kh20N80 nichrome, NP1 nickel, AMg63 aluminium-magnesium alloy. Studying these experimental results showed that at increase of the rate of accompanying protective air flow G2 from 0 to 40 m³/h, the loss of alloying elements (С, Mn) during spraying by steels wires of 65G and 70 grades decreases by 30…40 % on average. Increase of the parameter of rate G2 of the air flow accompanying the particle-loaded plasma jet influences improvement of the coating adhesion strength and wear resistance. So, at G2 = 20…40 m³/h the adhesion strength at tearing off of coatings from steel 70 along the normal reaches 60…70 MPa, and that of coatings from М2 copper is 40…55 MPa. Wear resistance of coatings under the conditions of boundary friction and resistance at cavitation wear increases at G2 increase from 0 to 40 m3/h, which is manifested in reduction of such wear from 1.35 to 0.32 mg/min. 13 Ref., 9 Fig. [ABSTRACT FROM AUTHOR]