Laser processing of SiC-particle-reinforced coating on titanium Mitun Das, a Vamsi Krishna Balla, b Debabrata Basu, a Susmita Bose b and Amit Bandyopadhyay b, * a Bioceramics and Coating Division, Central Glass & Ceramic Research Institute (CSIR), 196, Raja S.C. Mullick Road, Kolkata 700032, India b W.M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA Received 14 April 2010; revised 29 April 2010; accepted 29 April 2010 Available online 4 May 2010 Laser engineered net shaping has been used to create a Ti–SiC composite layer on Ti to improve its wear resistance. The influ- ences of laser power and scanning speed on the microstructure and wear resistance of the coatings were examined. Laser parameters were found to have a strong influence on the dissolution of SiC, leading to the formation of Ti 5 Si 3 and TiC with a high amount of SiC on the surface. The composite coatings with hardness between 976 and 1167 HV exhibited average wear rate between 5.91 and 6.60  10 4 mm 3 (N m) 1 . Ó 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Titanium; Silicon carbide; Laser treatment; Microstructure Titanium and its alloys have been widely used in aeronautical, chemical and defence industries due the high specific strength, stiffness and excellent corrosion resistance of these materials [1]. However, its poor wear resistance is a serious concern for applications where abrasive and erosion phenomena are present. Therefore, there is an increasing interest in improving surface prop- erties of Ti through various surface modification tech- niques. In recent years, laser surface modification (LSM) has attracted the attention of various research groups due to several unique advantages [2]. LSM offers high heating/cooling rates (10 3 –10 8 Ks 1 ) for the devel- opment of non-equilibrium phases with fine grained microstructure and novel properties [3]. Using LSM, a wide range of surface compositions and structures can be developed by varying processing variables such as la- ser traverse speed, power, beam size, precursor compo- sition and feed rate [4]. Most LSM coatings are metallurgically bonded to the substrate, providing a sound and adherent interface. Injection of ceramic powders into the laser-melted surface of a metal eliminates sharp interface between the coating and the substrate. These metal matrix composite (MMC) layers create structures with high hardness and excellent wear and erosion resistance [5– 7]. Among various ceramics SiC particles are the most commonly used reinforcement for Ti and its alloys [6,7]. It has been shown that SiC-reinforced Ti–6Al–4V alloy, produced via laser treatments, exhibits noticeable improvement in wear resistance [8,9]. However, the mechanical performance of SiC based MMC layer strongly depends on the degree of dissolution of SiC in the matrix and the type of reaction layer [6–9]. Further high cracking tendency of SiCp/Ti–6Al–4V MMCs, due to the different thermal expansion coefficients between Ti–6Al–4V and SiC [9], is a serious concern, which can be minimized by functionally graded coatings [7]. Although earlier studies [6,7,10] report in-depth analysis of reactions between Ti and SiC during laser processing, studies related to wear performance of SiC-reinforced Ti coatings are limited. These earlier works also indicate that laser power between 1 and 2.8 kW leads to severe dis- solution of SiC particles. Kloosterman et al. attempted to control the dissolution of SiC by changing the position of particle injection into the melt pool [10]. In the present investigation, hard SiC ceramic has been deposited on Ti substrate using laser engineered net shaping (LENSe) – a solid freeform fabrication technique, at low laser powers of 300 and 400 W. This article focuses on the influence of laser power and scan 1359-6462/$ - see front matter Ó 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.scriptamat.2010.04.044 * Corresponding author. Tel.: +1 509 335 4862; fax: +1 509 335 4662; e-mail: amitband@wsu.edu Available online at www.sciencedirect.com Scripta Materialia 63 (2010) 438–441 www.elsevier.com/locate/scriptamat