Optimisation of HVOF Spray Process Parameters to Achieve Minimum Porosity and Maximum Hardness in WC-10Ni-5Cr Coatings

Pradeep Raj Rajendran,Sathiyamoorthy Ranganathan,Laxmi Renjith,Guruprasad Balachandran,Ashokkumar Mohankumar,Kaliyamoorthy Murugan,Thirumalaikumarasamy Duraisamy,Ramachandran Chidambaram Seshadri

doi:10.3390/coatings12030339

Pradeep Raj Rajendran, Sathiyamoorthy Ranganathan + Show 6 more

Open Access

https://doi.org/10.3390/coatings12030339

Copy DOI

Abstract

High-velocity oxy-fuel (HVOF) spray coating plays a major role in many surface treatment methods, which tend to improve erosion and corrosion resistance properties. HVOF is well known for its dense and high-quality coating ability. This is due to the less in-flight exposure time, which tends to have less oxide content because of its high-velocity properties. Among the number of process parameters, porosity and hardness are predominant factors while considering wear rate and corrosion behaviour analysis. The current study aims to optimise HVOF process parameters to obtain low levels of porosity and high hardness values in the WC-10Ni-5Cr coating sprayed on 35 Mo Cr steel. The flow rates of oxygen, LPG, coating powder feed rate and spray distance are selected in this study as these have a superior influence on the final condition of the coating. Statistical tools such as the design of experiments (DoE), analysis of variants and response surface methodology (RSM) were used to achieve the desired results. As per the result analysis, the oxygen flow rate has a higher effect on the porosity value and microhardness value of the coating.

Highlights

Coatings have always played an essential role in empowering industries to fight problems of the early ruin of components that operate in severe environmental conditions
The final empirical relationship was recognised with these significant coefficients
The results show that deviating from the optimised spray conditions increases coating porosity while decreasing coating hardness due to a lack of energy supplied to powder particles by the high-velocity oxy-fuel (HVOF) flame, variations in in-flight time and variations in spray distance

Summary

Introduction

Coatings have always played an essential role in empowering industries to fight problems of the early ruin of components that operate in severe environmental conditions. Sprayed coatings have some diverse advantages over other surface enhancement methods as they can be deposited over a wide range of thicknesses, even in complex geometries, without any constraints at lower costs. Thermal spray types such as high-velocity oxy-fuel (HVOF), atmospheric plasma spraying (APS) processes and cold spraying are adopted by industries for developing coatings to battle against varied forms of surface degradation problems.

Methods

Results

Conclusion