Optimizing HVOF Spray process parameters and post-heat treatment for Micro/Nano WC–12%Co, mixed with Inconel-625 Powders: A Critical Review

Abstract In the recent past, the increase in production and operational costs in the oil and gas industry, particularly as a result of corrosion and wear effects, has prompted engineers to focus more on effective surface... [ view full abstract ]

Abstract

In the recent past, the increase in production and operational costs in the oil and gas industry, particularly as a result of corrosion and wear effects, has prompted engineers to focus more on effective surface treatment approaches on the machinery being manufactured. In particular, the Gulf region, which is undoubtedly one of the richest regions globally in terms of oil deposits, has attracted significant attention with regard to modern engineering materials due to its harsh environment. High Velocity Oxy-Fuel (HVOF) is an example of one of the thermal spraying techniques which are used to protect industrial components from corrosion, wear, abrasion, fatigue and high operational temperature conditions. The oxidation which sometimes occurs during particle spraying can lead to porosity and inhomogeneity in the distribution of the
coating. This inhomogeneity creates small holes that enhance corrosion due to exposure to corrosive gases in a corrosive environment. Also, residual stresses occur due to the thermal expansion coefficient mismatch between the coating and the base metal or in cases where the coating layer is too thick. However, optimization of the HVOF Thermal Spray parameters has been employed to improve the coating through design improvements to ensure homogeneity to improve corrosion and erosion resistance and consistent reactions due to temperature increases with the addition of neutralizing chemicals.
An alloy that has been successfully applied to improve the component’s surface characteristics against wear and corrosion is Tungsten carbide cobalt (WC-12Co), both the micro sized Diamalloy 2004 and the superfine nanostructured InfralloyTMS7412, mixed with Inconel 625 (Ni-Cr alloy) Diamalloy 1005 alloy.
This paper will review the development and optimization of the HVOF thermal spraying process for these coating materials;it will investigate the outcomes of optimizing spraying temperatures, spraying distances and powder feed rate parameters.
The paper will also review some methods of post-heat treatments that have been applied to enhance the coating quality discussed in works published over the past 15 years.

Keywords: coating, Thermal spraying coating, HVOF, spray parameters, optimization, post-heat treatment