Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom Parametric optimization of atmospheric plasma spray coating using fuzzy TOPSIS hybrid technique B. Swain a , M. Priyadarshini b , S.S. Mohapatra c , Ram K. Gupta d , Ajit Behera a, ⁎ a Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, India b Department of Mechanical Engineering, National Institute of Technology, Rourkela, India c Department of Chemical Engineering, National Institute of Technology, Rourkela, India d Department of Chemistry, Kansas Polymer Research Center, Pittsburg State University, Pittsburg, KS, USA article info Article history: Received 22 January 2021 Received in revised form 30 January 2021 Accepted 2 February 2021 Available online 9 February 2021 Keywords: Plasma spray Coating NITINOL Fuzzy TOPSIS ANOVA Characterization abstract In the work, an elemental mixture of Ni and Ti was deposited by atmospheric plasma spray technology on the mild steel substrate by varying the process parameters such as primary gas fow rate and plasma arc current. The properties such as surface roughness, microhardness, and erosion rate of the coating were determined and the relationship between process parameters and coating properties was established. To optimize the process parameters and to fnd out the optimum parametric setting, the fuzzy technique for order preference by similarity to an ideal solution hybrid technique was im- plemented. By keeping all the parameters constant, the coating with better properties was obtained at an optimum parametric setting of 550 A arc current and 45 lpm primary gas fow rate. Furthermore, by implementing the Analysis of Variance, the primary gas fow rate was found to be a signifcant con- tributing factor. The X-ray diffraction analysis of the coating developed at an optimized parametric setting revealed Ni, Ti, NiTi-B2 phase, Ni 3 Ti, Ti 2 Ni, Ni 4 Ti 3 , TiO, and NiO phases. The bonding of the coating with the substrate was confrmed by the line scan energy dispersive spectroscopy analysis. The surface morphology of the eroded surface of the coating developed at the optimum parameter revealed the crater formation, chip formation, lip formation, plastic deformation, and groove formation mechanisms. © 2021 Elsevier B.V. All rights reserved. 1. Introduction Niclel-Titanium (NITINOL: National Ordinance Laboratory) is an advanced material which can regain its shape after releasing of external stimuli [1,2]. It has two astonishing properties such as shape memory effect and pseudoelasticity due to which it is also known as smart material. These abovementioned properties at- tracts the attention of various researchers for different applica- tions of this material such as aerospace and naval [3], biomedical [4], civil constructions [5] etc. Atmospheric plasma spray (APS) coating is one of the promi- nent deposition methods which develops protection from ero- sion, abrasion, corrosion, high temperatures, and chemical attacks [6–13]. The process consists of the injection of powder feedstock by the carrier gas to the plasma fame in which the melting of powder particles is attained due to the heat transfer between the particle to particle and plasma to particles and f- nally, the molten, semi-molten, and unmelted particles strike the substrate at a high velocity to build up the coating [14–21]. As a versatile technique, it can deposit a variety of materials such as metallic, ceramic, cermet, and composite [22–24]. This process has been expanded in various industries like aerospace, auto- mobile, nuclear, and many other industries due to its versatility [25]. In the atmospheric plasma spray process, the output/result/ properties depend upon the input process parameters. To achieve the best quality of coating, it is important to understand the ef- fect of process parameters and the phenomena that occurs during the coating process. Modeling of the plasma spray process and its analysis is gaining importance rapidly. The follow-up research revealed the hierarchical control and factory automation processes which were widely accepted. However, the above-mentioned techniques seemed complex due to the interaction between the operating https://doi.org/10.1016/j.jallcom.2021.159074 0925-8388/© 2021 Elsevier B.V. All rights reserved. ]] ]] ]]]]]] ⁎ Correspondence to: Advanced Materials Processing and Research laboratory (AMPRE-Lab), Department of Metallurgical and Materials Engineering, NIT, Rourkela 769008, India. Journal of Alloys and Compounds 867 (2021) 159074