Effect of Vacuum Annealing on the Nickel-Based Coatings Deposited on a CGI Cast Iron through Atmospheric Plasma Spraying

Peihu Gao,Minxian Liang,Shencong Zeng,Yongchun Guo,Zhong Yang,Tao Xu,Baiyang Chen,Jianping Li

doi:10.3390/met10070963

Peihu Gao, Minxian Liang + Show 6 more

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https://doi.org/10.3390/met10070963

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Abstract

Plasma-sprayed nickel-based self-fusion alloy coatings were annealed in a vacuum at 990, 1020 and 1050 °C for 20 min to increase the bonding between the compacted graphite cast iron substrate and coating, as well as the inner cohesion of the coatings. It was found that nickel and chromium diffused between nickel-based alloy coatings and compacted graphite cast iron substrate. A metallurgical translation zone with a thickness up to 1145 μm formed during the vacuum annealing, which resulted in an enhancement of the adhesion between the coating and substrate. The adhesion strength at room temperature was increased from the as-sprayed coating of 33.4 MPa to the annealed one of 163 MPa. Meanwhile, the adhesion strength at 500 °C reached 146 MPa. Conversely, the inner cohesion of the coating was improved with the particles’ interfaces healed after vacuum annealing. The micro-hardness of the annealed coatings was increased to 902 HV from the as-sprayed one of 578 HV.

Highlights

Cast irons have been widely used as engineering parts [1,2,3]
The top surface of the nickel-based coating became smooth, which seemed like the coatings’ surfaces coating, which is commonly known as diffusion transfer bright (DTB) [34,36]
RuT300 was investigated to improve the adhesion between coatings and substrate as well as iron RuT300 was investigated to improve the adhesion between coatings and substrate as well as the the cohesion of the coatings

Summary

Introduction

Cast irons have been widely used as engineering parts [1,2,3]. Compacted graphite iron has garnered more attention for its high strength, similar to nodular iron, and high thermal conductivity, comparable to the gray iron, while wear often takes place in compacted graphite iron engine parts, especially at high temperature [4,5,6]. Nickel-based alloys are widely used in anti-corrosion and wear-resistant applications for their excellent high-temperature properties [7,8,9,10]. Nickel-based self-fusion alloy coatings offer both good anti-corrosion and good wear resistance [11,12,13,14]

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Discussion

Conclusion