Journal of Thermal Spray and Engineering, 1(1): 1-6 ISSN (Online): xxxx-xxxx; 10.jtse/xxxx-xxxx/1-1.1 Corresponding Author: Ajit Behera, Tel: +91- 09938383765 © 2018 Science IN. All rights reserved Email: ajit.behera88@gmail.com Contents lists available at http://www.inscience.in/JTSE.html Sensitivity of Process Parameters in Atmospheric Plasma Spray Coating Biswajit Kumar Swain 1 . Soumya Sanjeeb Mohapatra 2 . Ashutosh pattanaik 3 . Sumant Kumar Samal 1 . Subrat Kumar Bhuyan 1 . Kasinatha Barik 4 . Deepak Kumar Sahoo 5 . Ajit behera 1 1 Department of Metallurgical & Materials Engineering, National Institute of Technology, Rourkela, India. 2 Department of Chemical Engineering, National Institute of Technology, Rourkela, India. 3 Department of Mechanical Engineering, C.V.Raman College of Engineering, Bhubaneswar, India. 4 Department of Chemical Engineering, Indira Gandhi Institute of Technology, Sarang, India. 5 State pollution control board, Govt. of Odisha, Rourkela, India. ABSTRACT Atmospheric plasma spraying (APS) is one of the most widely used thermal spraying technique which finds a lot of applications due to its versatility of spraying a wide range of materials from metallic to nonmetallic and hence more suitable for spraying of high melting point materials like refractory ceramics material, cermets etc. In recent era,any material can be used for plasma spraying on almost any type of substrate. Process parameters are the key factor that affects the formation of microstructures, bonding of coating with substrate and mechanical strength of coating. In this paper, the process parameters and their sensitivity towards the plasma modified structural elements are discussed.The microstructure of thermally sprayed coatings, which results from the solidification and sintering of the particles, frequently contain pores, oxides and cracks. The amount and distribution of these defects, as well as other coating properties as for instance thickness, hardness and bond strength, will be defined by the selected spray parameters. Therefore, the correct choice of the spray process as well as respective parameters (particle size, particle velocity, spray distance, plasma gun power, working pressure, substrate roughness, substrate temperature and so on) is very important for the deposition of good coatings and, consequently, to enlarge the useful life in service of the components. ARTICLE HISTORY Received 15-01-2018 Revised 31-01-2018 Accepted 01-02-2018 Published 06-04-2018 KEYWORDS Plasma Spraying Gun Power Powder Size Phase Composition Substrate Temperature © 2018 JTSE and Science IN. All rights reserved Introduction Plasma is an electrically conductive gas containing electrically charged particles, ions and electrons. In plasma spraying process, metals, alloys, high melting-point materials, such as ceramics and cermets in powder or wire form are melted and sprayed onto the subjects by using plasma jet as its heat source over 1000°C. Plasma spraying has two type of methods APS which is carried out in the atmosphere, and VPS, carried out in the vacuum. APS process has a wide range of material choice and high level of adhesiveness. APS coating with advanced features as well as all-out quality control is widening its application fields. APS deposition is widely used since the beginning of 1980s. APS is one of the most versatile and rapid techniques to deposit protective overlay coatings onto the surface of components to increase their in-service properties especially under severe conditions [1-5]. APS has been widely used in different industries as given in table 1, due to their good mechanical properties and corrosion resistance [6-8]. APS coating materials widely used in the cathodic protection of steels are aluminum, zinc, ZnAl and AlMg alloys [9]. The main plasma spraying operating parameters that have an influence on deposition phenomenon are: the plasma gun power, primary gas in plasma chamber, carrier gas, working pressure, powder size, powder injection Angle, powder phase composition, substrate roughness, and substrate temperature are discussed in this paper. Table 1: Typical applications of APS in different industries Aerospace Gas Turbine and Airframe components [10] Marine Anti-fouling coating, anti-skid decking, propellers, shaft [11] Electronics RF shielding, insulators[12] MEMS silicon chip production equipment [13] Automotive and transportation Engine and drive train components, mould release coating [14] Textile machinery Stretch-Tow Rollers, Thread Guides [15] Power generation Gas turbine components and cases, hydroelectric turbine components, steam turbine components, solid oxide fuel cells [16] Petrochemical Pump components, valves, tank linings [17] Pulp, paper and printing machinery Anilox rolls, impression rolls, corona rolls, boilers, digesters, paper manufacturing rolls and components [18] Metal processing Sink rolls, extrusion rolls, extrusion dies [19] Biomedical Orthopedic implants [20] Cutting tool Steel cutting tool, non-steel cutting tool equipment [21] Nuclear Reactor equipment [22] Effect of plasma gun powder Optimum gun power is required to enhance the deposition efficiency. With small current, the energy density of plasma flame is low, only smaller powder is molten or partially-molten, larger size powder has little positive effect on deposition efficiency (DE) and inter-particle porosity increases. With increasing spraying current, the percentage of molten or semi-molten powder particle tends to increase, but the smaller size powder tends to vaporize at the time which affects the density by