Improvement of electric spark surfacing method

Abstract

Electric spark treatment of wear-resistant coatings is one of the resource-saving technologies that improve the durability of parts of mechanisms and machines. The limitations of the use of this technology are low performance, non-continuity of the coating, high roughness, as well as limited thickness of the surfaced layer. (Research purpose) The research purpose is to study the effect of additional introduced DC voltage between the electrode and the product, as well as the effect of different brands of electrodes on the thickness of the spark coating. (Materials and methods) Conducted research on the SZ-8100 micro-welding apparatus, the source of additional input voltage was the SHE-56 laboratory autotransformer, changed the voltage in the range of 0-75 volts; as materials for the electrode used wolfram, nickel, 65G steel, VK20 metal-ceramic alloy. (Results and discussion) It was found during the spark surfacing with additionally introduced constant voltage between the electrode and the workpiece, that with increasing DC current increasing of coating thickness is observed when using the electrode made of 65G steel on modes 1 and 2, wherein the maximum thickness recorded at a current of 13-17 and 23-26 amps. It was also found that electrodes of nickel, wolfram, ВК20 showed no changes in coating thickness with increasing voltage between the electrode and the workpiece, however, at the maximum modes of operation of SZ-8100 microsurfacing apparatus (mode 3) with increasing voltage, the thickness of 65G steel, wolfram and ВК20 decreases compared to the initial state (without additional imposed voltage between the electrode and the workpiece). It was noted that the destruction of the electrode material occurs in these modes. (Conclusions) An effective electrode for increasing the thickness of the surfacing layer by introducing an additional constant voltage between the electrode and the product was an electrode made of 65G steel.