Study of the Processes of Forming a Metal Coating by Cold Gas-Dynamic Sputtering and Development of a Technique for Calculating Sputtering Modes
O. L. Haydamak, V. F. Hraniak
Vinnytsia National Agrarian University, 3 Sonyachna str., UA-21008 Vinnytsia, Ukraine
Получена: 17.09.2023; окончательный вариант - 22.10.2023. Скачать: PDF
The creation of various functional coatings on the surfaces of parts allows to influence the technical and operational characteristics of the parts and to give to these parts new qualities extrinsic for parts without coating. The principle of creating coatings is based on the effect discovered in the 1980s of the previous century, which consists in the fact that powder particles accelerated to high speeds close to the speed of sound, when they collide with the substrate, enter into molecular bonds with it and are able to form a strong connection both with the latter and between its own dispersed particles themselves. At the same time, the temperature of the powder coating process is significantly lower than the melting point of the powder coating material. The installation for cold-gas-dynamic spraying of metal coatings is designed and manufactured. The main components of this installation are a compressed air heater and a nozzle-accelerator of heated compressed air. In accordance with the ejection effect, finely dispersed metal powder with an average particle size of 60 µm is fed into the nozzle, which accelerates in the nozzle channel and, because of heat exchange with hot air, is heated to a temperature that is significantly lower than the melting point of the powder material. As a result, the part and powder material do not undergo phase transformations and, accordingly, do not change their properties and do not undergo significant thermal deformations. The patterns of sputtering shape formation using powder based on aluminium grade A20-11 are studied. As established, the formation of the sputtering shape profile in the general case can be described in accordance with the Gaussian-distribution law. After analysing the relative deviation of the Gaussian function from the experimental profile of the sputtering figure, it is established that the largest deviations of the theoretical figure from the experimental one are observed at the periphery of the sputtering figure with a coating thickness not exceeding 0.1 mm; and the smallest deviation occurs in the middle zone on the axis of the sputtering figure, where there is the place of the most intensive formation of the coating. Considering the above, it can be concluded that the Gaussian distribution describes the shape of the sputtering figure profile with great reliability. The average integral relative error of the Gaussian function does not exceed 9%. A methodology for modelling the coating creation process is proposed, which allows predicting the shape of the sprayed figure profile depending on the productivity of the spraying device. This profile enables to establish an optimal interval between adjacent passes of the nozzle-accelerator over the surface of the workpiece. The proposed method allows to calculate the optimal nozzle-accelerator movement speed relative to the workpiece, the rotational speed of the workpiece, the required amount of powder for coating a given workpiece, the spraying time, and reducing unnecessary powder losses to a minimum, considering the productivity of the coating creation process and the powder utilization coefficient.
Ключевые слова: gas-dynamic sputtering, sputtering shape, calculation of movement speed.
URL: https://mfint.imp.kiev.ua/ru/abstract/v45/i12/1485.html
PACS: 44.90.+с, 81.15.Cd, 81.20.Rg, 81.65.-b, 83.50.Ha, 83.55.Rx