Abstract
Electrospark coating deposited on the surfaces of machine parts is a common surface hardening method. Hard materials are normally used for depositing to improve wear resistance or other properties. In this investigation electrospark deposition intended for use as micro-alloying of welds by deposition on to the surface of the base metal and in this case it remelts completely. Intense heating and destruction occurs before remelting, which changes the chemical composition of the melt. The aluminum and titanium coatings is shown to deteriorate at 500 to 650 °C generating a liquid phase due to eutectic available in both metals in this temperature range. Most of titanium and aluminum oxidized at that. It is found that a solid layer, appears after electrospark depositing using both coatings. For aluminum coating, after high-temperature heating, a thicker white layer appears with the same microhardness level as that of the base metal, and a thin layer of partial decarburizing. Fusion sectors are detected in the titanium coating that are harder than the base metal and have a dendritic structure, followed by a thin zone of complete decarburization and quite an extended zone of partial decarburization.
Highlights
Metal deposition on the surface during electric spark discharging occurs as a result of the cathode sputtering effect
Complete and partial decarburizing zones occur behind the melting sectors, of which on zone is narrow, about 200 μm, and the other is of about 1 mm deep (Figure 3 b,c, 4 d)
Summary when the electrospark deposited layers by aluminum and titanium electrodes are heated to high temperature, the surface layer melts followed by diffusion redistribution of elements
Summary
Metal deposition on the surface during electric spark discharging (electrospark deposition – ESD) occurs as a result of the cathode sputtering effect. In a molt pool on the anode appears cavern due to displacement by the spark discharge pressure. This molten area receives, most likely, liquid drop going off the cathode. The aluminum and titanium microalloying effect is beneficent for welded metal properties [9,10,11,12], so in this paper we studied changes in the near-surface volume after electrospark deposition and high-temperature heating before welding melting.
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