Characterization and slurry erosion mechanisms of Nickel-Based cermet coatings on monel K-500

Abstract

Monel K-500 is a nickel-based alloy broadly used in several industries such as power generation, aerospace, marine and chemical processing for manufacturing several critical components. During hydraulic applications, the alloy is subjected to different degradation phenomena such as cavitation erosion, slurry erosion and corrosion. The current study assesses the potential of using two HVOF-sprayed nickel-based cermet coatings: WC-10Ni5Cr and WC-18Hastelloy C to control the slurry erosion of Monel K-500. The coatings were subjected to slurry erosion tests for 90 min at normal (90) and oblique (30) impingement angles. It was observed that these coatings significantly reduced the erosive wear in Monel alloy. WC10Ni-5Cr coating, having relatively better microhardness and fracture toughness has shown minimum erosion losses. At normal impact, WC-10Ni-5Cr coating and WC18Hastelloy C coating reduced the erosion rate of Monel by 2.3 and 1.6 times, respectively. At oblique impact, WC10Ni-5Cr coating and WC-18Hastelloy C coating reduced the erosion rate of Monel by 4.75 and 2.4 times, respectively. In-depth study of the erosion mechanism for the investigated materials was conducted using scanning electron microscopy. Ploughing and micro-cutting were the primary erosion mechanisms in Monel alloy, whereas coating spallation and crater formation were the primary erosion mechanisms in the coatings.