Influence of Process Parameters and Geometry of the Spraying Nozzle on the Properties of Titanium Deposits Obtained in Wire Arc Spraying

Abstract

Influence of the process parameters and geometry of the spraying nozzle on the properties of titanium deposits obtained in wire arc spraying. Wire arc spraying is a process in which through minor modifications of the spray parameters, they can have a major impact on the coatings properties. In this paper there is presented a study on the influence of process parameters and fluid dynamics of the atomization gas on the properties of titanium deposits (14T - 99.9% Ti). For this there were used three different frontal spraying nozzles, having different geometries, and were varied the spraying gas pressure and the electrical current on three levels. There were evaluated the particles velocity, coating density, chemical composition and characteristic interface between deposition and substrate. Obviously, the high speed of the atomization gas determinate the improving of all properties, but in the same time increased the oxide content in the layer. However, the oxidation can be drastically reduced if the melting and atomization of the wire droplets is produced at the point of formation of the electric arc, and the spraying jet is designed to constrain the electric arc. The assessment of deposits adherence allowed the observation of process parameters that contribute to its improvement.

Effect of spraying parameters on surface roughness, deposition efficiency, and microstructure of electric arc sprayed brass coating

“…There were also "cracklike" pores that show their presence within the lamellae structure. The formation of cracks between the lamellae is due to the oxidation of the inflight molten particles (Toma et al, 2015). The presence of pores and cracks within the coating layer itself indicates that a relatively poor cohesion between the coating splats may exist.…”

“…Various parameters in thermal electric arc spraying technique which affect the quality of coating comprise the voltage, current, wire feed rate, spray off distance (SOD), nozzle geometry, (Li and Li, 2005;Wilden et al, 2005;Toma et al, 2013a;2013b;Matz and Aumiller, 2014) coating's surrounding environment (inert, ambient or vacuum chamber), pressure of atomized gas, feedstock material (Mauer et al, 2017), type of atomized gas (air or nitrogen), preheating of the substrate surface or post heat treatment of coating lamellae (Chen et al, 2010;Zhou et al, 2017) and type of surface preparation (shot blasting, sandblasting, rough threading) (Georgescu et al, 2015). The EAS coating technique produces the coating of high porosity, high oxide content, low DE, and high SR (Toma et al, 2015;Adamiak et al, 2018;Bonabi et al, 2018). Therefore, the optimization of the EAS parameters is essential to achieve effective coatings for particular applications (Salavati et al, 2016;Hvozdets'kyi et al, 2018;Darut et al, 2015).…”