Microhardness and Corrosion Resistance of HVOF Sprayed NiCr Coating with SiC Addition

International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue IV, April 2018 | ISSN 2321–2705

Microhardness and Corrosion Resistance of HVOF Sprayed NiCr Coating with SiC Addition

Arun Raphel ^1*, Lovin Varghese ²

  ^{1, 2} Department of Mechanical Engineering, Viswajyothi College of Engineering & Technology, Vazhakulam, Ernakulam- 686670, Kerala, India

Abstract: High Velocity Oxy-Fuel (HVOF) thermal spraying technique is widely used in many industries to protect the components against erosion, corrosion and wear [1]. It produces coatings with low porosity, low oxide content, better density, better coating cohesive strength and bond strength than many thermal spray processes. Ni based alloy coating is widely used for enhancing the wear and corrosion resistance at higher temperatures. Even though NiCr alloy having excellent wear and corrosion resistant properties, it is not used as the primary material in the industry because of lower hardness in comparison to other materials (carbides and ceramics) [2]. But it was incessantly proved that Ni based alloy coating reinforced with additives giving good results in the field of erosion-corrosion resistance. Various hard phases used as reinforcing additives along with NiCrSiB are WC, Al₂O₃, Cr₃C₂, Cr₂O₃, TiC, TiO₂ SiC, TiN etc [3]. In that respect, the addition of has SiC gained attention due to its higher hardness, wear and oxidation resistance and low cost.

In this work, the effect of addition of SiC particle on the micro hardness and corrosion resistance of NiCrSiB coating on mild steel substrate is discussed. The SiC added feed stock power was prepared by mechanical alloying and the coating was developed using HVOF technique. The microhardness and toughness of the coatings were measured using Vickers’s microhardness tester. Corroion resistance was measured using Potentiodynamic polarization test with 3.5% Nacl.

Key words: Corrosion Resistance, Thermal spray coatings, Microhardness

I. INTRODUCTION

The demands for engineering coatings are becoming more and more stringent. Environmental concerns are also being considered as an integral part of the design process. For future economic competitiveness and a lower environmental impact, we must therefore turn our attention to processes that use the minimum of resources. Thermal spraying is an attractive coating technique as it offers a wide choice of materials and processes that have a reduced impact on the environment when compared to conventional plating processes.

Read More