Дослідження впливу температури газу процесу холодного газодинамічного напилювання на адгезійну міцність нікелевмісних покриттів

Abstract

The subject of the research is the influence of low-pressure cold spraying process parameters on the adhesive strength of the coatings. The goal is to ensure the maximum values of the adhesive strength of nickel-based coatings deposited by cold spraying by controlling the gas temperature at the nozzle inlet. The task is to investigate the effect of the temperature mode of the DYMET-405 machine on the adhesive strength of the coatings obtained from the Ni+Zn+Al2O3 powder mixture at constant other spraying parameters. Research methods. The experimental study of the adhesive strength was conducted on the tear using adhesive method in accordance with DSTU 2639-94. The metal-matrix composite powder mixture Ni+Zn+Al2O3 was used as powder material. VT3-1 titanium alloy was chosen as substrate material. Coatings were deposited using DYMET-405 low-pressure cold spraying machine. Temperature regulation at the nozzle inlet was performed by turning on the required temperature mode on the equipment control panel. Other spraying parameters remained constant during coating deposition process. The results. It was established that with an increase in the temperature of the gas in the nozzle, an increase in the adhesive strength of coatings is observed, on average from 9.5 MPa to 28.7 MPa. This can be explained by the fact that an increase in gas temperature leads to an increase in the velocity of the gas flow and, accordingly, of the powder particles in this flow. Higher particle impact velocity has a positive effect on the process of their deforming, filling of pores, densifying of coating layers, and finally increasing the adhesive and cohesive strength. The scientific novelty of the obtained results is that the dependence of the gas temperature at the nozzle inlet during low-pressure cold spraying on the adhesive strength of Ni+Zn+Al2O3 powder mixture coatings deposited on VT3-1 titanium alloy substrates was obtained. Conclusions. The practical value of the obtained results is that the obtained dependences of adhesive strength on gas temperature can be used for the development of cold spraying recommendations for the deposition of restorative coatings on parts made of titanium alloys, in particular in aircraft engines to eliminate operational defects.