PREDICTION OF MICROHARDNESS OF ASD-1 POWDER COLD SPRAYING COATINGS

Purpose. To develop a mathematical model for describing the dependence of the microhardness of ASD-1 aluminum powder coatings on the three main factors of the cold gas-dynamic spraying process using statistical methods of experiment planning. Research methods. Methods of statistical planning of multifactorial experiments and regression analysis were used to conduct experimental research. The analysis of microhardness was performed according to the standard methodology given in GOST 9450-76. Preparation of transverse microsections for microhardness studies was carried out according to standard methods for preparing samples for metallographic analysis of microstructure. The specialized computer program Stat-Ease 360 was used to process statistical data. Results. The complex effect of cold gas spraying process parameters on the microhardness of ASD-1 powder coatings in a wide range of values was investigated. According to the results of experimental studies, it was established that in the investigated ranges of the deposition modes, it is possible to obtain microhardness of coatings in range from 49 to 66 HV0.15. The dispertion analysis results showed that the gas temperature and the stand-off distance have the greatest effect on the microhardness of the coatings, while the powder feed rate has no significant effect on the microhardness. The obtained regression equation can be used to predict the microhardness of coatings from the ASD-1 powder, and the error between the calculated and actual values does not exceed 5%. Scientific novelty. Empirical dependences of the microhardness of ASD-1 powder coatings, deposited by cold spraying, on the gas temperature at the nozzle inlet, stand-off distance, and powder feed rate in the specified ranges of values were obtained. Practical value. The obtained dependences of the coating microhardness on the process parameters can be used to select modes of cold spraying of protective and restorative coatings, in particular on aircraft engine parts.