S. Kumar, J. S.Ratol: Effects of Tribological Parameters on Slurry Erosion Behaviour of Uncoated and Coated Materials: A Review Materials Engineering - Materiálové inžinierstvo 20 (2013) 119-131 119 Effects of Tribological Parameters on Slurry Erosion Behaviour of Uncoated and Coated Materials: A Review Sunil Kumar 1,* , Jasbir Singh Ratol 2 1 Chitkara School of Mechanical Engineering, Chitkara University, Rajpura, District Patiala, Punjab, India- 140401 2 Department of Mechanical Engineering, Baba Banda Singh Bahadur Engineering College, Fatehgarh Sahib, Punjab, India-140407 * corresponding author: e-mail:sunil14478@yahoo.co.in Resume This paper describes the pioneering work of various researchers in the field of slurry erosion behaviour of uncoated and coated materials in various industrial applications. The present study is focused on the slurry erosion behaviour of ash slurry disposal system of thermal power plants. The key components such as impeller and casing of ash slurry disposal pumps in thermal power plants experience this phenomenon of wear. Tribological parameters such as solid particle concentration, impact velocity of erodent on the target surface, impact angle, erodent particle size and shape, hardness of the striking particles and target material, etc. are responsible for slurry erosion. The research results show that the influence of tribological parameters on the slurry erosion is found to be significant and need to be evaluated and analyzed properly. The slurry erosion can be minimized by proper selection of materials and/or by providing the suitable protective coating on the material which can enhance the surface properties. Available online: http://fstroj.uniza.sk/journal-mi/PDF/2013/16-2013.pdf Article info Article history: Received 17January 2013 Accepted 23April 2013 Online 10 September 2013 Keywords: Slurry Erosion; Thermal Spray Coatings; Physical Vapour Deposition Process; Chemical Vapour Deposition Process; Nano-structured Coatings. ISSN 1335-0803 (print version) ISSN 1338-6174 (online version) 1. Introduction Slurry erosion is found to be serious problem in power generation component such as ash slurry disposal pumps (impeller and volute casing) in thermal power plants and hydraulic turbines (runner, guide vanes, needles and seats) in hydro-electric power plants and should be either totally prevented or detected at an early stage to protect the system for maximum utilization. Slurry erosion mechanism is shown in fig. 1. The erodent particles present in the slurry strikes the surface of target material with high velocity and the erosion takes place. In thermal power plants, the bed ash and fly ash is mixed with clean water in main mixing tank to form combined slurry. Once the combined slurry density reaches the target level, a centrifugal slurry pump conveys the slurry out of the plant [1]. Fig. 2 shows the schematic diagram of ash handling system of thermal power plant. The impeller and volute casing of centrifugal slurry pump get exposed to slurry erosion due to the impact of high velocity ash particles of slurry on the surface of impeller and casing [2]. The target materials may be nickel hardened alloy steels, chromium alloyed cast iron, stainless steel, aluminium alloy, brass, mild steel etc. The solid particles which may use as erodent in industrial applications are fly ash, bed ash, silica sand, quartz, feldspar, muscovite, biotite, garnet, tourmaline, clays, volcanic ash, alumina and silicon carbide etc. Wells et al. [3] have studied the ash content, major minerals and trace elements, in 10 coals and found the maximum ash content in Indian coal. Table 1 shows the Indian coal with dry ash content and mineral matter. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA. This copy of the article was downloaded from http://www.mateng.sk , online version of Materials Engineering - Materiálové inžinierstvo (MEMI) journal, ISSN 1335-0803 (print version), ISSN 1338-6174 (online version). Online version of the journal is supported by www.websupport.sk .