ORIGINAL PAPER Influence of Silica on Microstructural Modification of Electrical Discharge Composite Coating and its Wear Performance Ilangovan Arun 1 & C. Yuvaraj 1 & P. Jyothibabu 1 & G. Chandra Sekhar Reddy 1 Received: 16 July 2019 /Accepted: 25 November 2019 # Springer Nature B.V. 2020 Abstract Electrical discharge coating a significant process of depositing alloying materials over the surface for improved wear resistance. In present investigation reinforcement of silica with a varying concentration in working fluid together with carbon over duplex stainless steel and their effects on coating formation, porosity, microstructure, microhardness and wear resistance properties under the elevated temperature of 600 °C has been investigated. While the silica percentage increases the surface roughness, deposition of carbon and porosity of the coating are reduced, with varying decarburizing depth, frictional coefficient and modified microstructure having finer in phase transformation beneath the coating. The carbide bands the microstructure of the pyrolysis carbon retains outstanding metallurgical bonding, grain refinement and makes hard metal matrix composite layer towards high temperature wear resistance. The frictional coefficient at higher temperature reduces while the carbon percentage increases the specific wear rate due to oxides that minimize the third body wear. Keywords Electrical discharge coating . Surface topography . Microstructure . Wear . COF 1 Introduction Surface coatings are provided over the materials to in- crease its severability and to attain improving its various properties such as hardness, wear, corrosion and fatigue. The process of coating made through various approaches having a different microstructural constitution basically depends on the equipment ’s process parameters. Increase in demand and rapid technological development of surface modification/ coatings improves aesthetic na- ture with resisting against various environmental condi- tions, the major techniques like electroplating having the microstructural constitution of the fine equiaxed struc- ture, where else Physical Vapour Deposition (PVD) hav- ing columnar structure, Chemical Vapour Deposition (CVD), laser, sputtering, ion implantation, spark deposi- tion etc., are having mixed structure based on various factors, the above processes needs special post- processing and curing are expensive [ 1 ]. Electrical Discharge Coating (EDC) a process of depositing the alloying elements (Including Carbides and Ceramics) through non-conventional electrical discharge machining (die sink) that adapts for machining hard materials that eliminates mechanical stress. This coating process is cat- egorized into two distinct, powders dispersed in the di- electric fluid termed as Powder Mixed Electrical Discharge Machining (PMEDM) and through green/ semi-sintered compacted powder as an electrode through powder metallurgy route termed as (P/M) to improve surface quality with effective microstructural modifica- tion for improved mechanical properties [2, 3]. In gener- al both of the above process enlarges the spark gap with dense electrical field results in continuing restructuring the electric discharges sparks than normal machining. However, ionization took place inside the dielectric (Hydrocarbon) fluid remains resulted in the formation of hardened white layer. In general, increasing the carbon content over work materials through EDM having a mi- crostructural constitution of columnar and dendritic struc- ture of iron carbide having superior hardness and corro- sion resistance [4, 5]. An advancement, reversing the * Ilangovan Arun arunnbrothers@gmail.com 1 Center for Advanced Material Processing, Madanapalle Institute of Technology & Science, Madanapalle, Andhra Pradesh 517325, India Silicon https://doi.org/10.1007/s12633-019-00333-z