Friction and wear behavior of several hard materials G. Quercia a,b, * , I. Grigorescu b , H. Contreras b , C. Di Rauso b , D. Guti  errez-Campos a a Materials Science Department, Simon Bolivar University, Apdo. 89000, Sartenejas 1080-A, Venezuela b PDVSA-INTEVEP. Apdo. 76343, Caracas 1070-A, Venezuela Received 5 March 2001; accepted 21 May 2001 Abstract Sliding friction, abrasion and erosion tests were performed on several materials: cemented carbides, partially stabilized zirconia Mg±PSZ), electroless Ni±P coatings and SAE 4140 steel as reference material. Sliding friction test was carried out in a pin-on-disk system. A micro-abrasion test was performed using the ball cratering methods. The erosion test consisted an air stream carrying abrasive particles of SiC, impinging ¯at samples. Sizes of wear scars were determined by optical microscopy and laser pro®lometry. Scanning electron microscopy SEM) and energy dispersive X-ray EDX) were employed to observe morphological and chemical features of worn surfaces. The sliding pin-on-disk results of Ni±P coating showed smooth variation of the friction coecient mean values of 0.16±0.21), as well as the lowest wear rate compare with the other evaluate materials. Experimental results of the micro- abrasion test showed linear behavior between wear volume and sliding distance for all the evaluate materials. Cemented carbides showed the lowest wear rates followed by SAE 4140 steel, Mg±PSZ and Ni±P coating, respectively. Erosion test values ranked evaluated materials from lower to higher eroded volume as follows: SAE 4140 Steel, Ni±P coating, cemented carbides and Mg±PSZ ceramic. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Friction; Ball cratering; Solid erosion; Cemented carbides; Mg±PSZ 1. Introduction In the recent years, the extension of the lifetime of mechanical and structural parts through the wear control has become an important tool for the re- duction of production costs in the oil industry [1]. One of the possible solution to reduce the frequency of operation failures is the replacement of traditional materials as hardening steel by recently developed materials that are more resistant to severe wear. Several replacement materials have been pre-selected based on criteria of hardness, chemical stability and toughness: cemented carbides, partially stabilized zir- conia, ZrO 2 ±MgO doped) and electroless nickel phosphorus coating. 2. Experimental 2.1. Materials Five grades of WC±Co with Co contents between 4 and 17 wt% were considered for evaluation. Prior to the industrial use, these materials were tested in several wear devices in laboratory. The results of this test are re- ported and discussed. Evaluated materials also included cemented carbide samples with 0.2 wt% VC and 2.7 wt% Ta,V)C. The principal properties of these cemented carbides are summarized in Table 1 [1] and their micro- structure are illustrated in Fig. 1. The Mg±PSZ was characterized by grain size of the cubic phase, with 40 lm and the hardness 1020 HV 0:30 , and coarse precipitate of grain boundaries [2]. A representative SEM picture of this ceramic is shown in Fig. 1f). Electroless Ni±P coating with a 100 lm thickness, measured by optical microscopy 10±12 wt% P), applied by a local manufacturer, was evaluated. The micro- hardness of Ni±P coating heat-treated at 400°C for 1 h, was 873.2 HV 0:1 [1] see Fig. 1g)). The reference material was SAE 4140 steel with 328 HV 30 and a nominal chemical composition of: 0.38 C, International Journal of Refractory Metals & Hard Materials 19 2001) 359±369 www.elsevier.com/locate/ijrmhm * Corresponding author. E-mail addresses: querciag@pdvsa.com G. Quercia), grigores- cuc@pdvsa.com I. Grigorescu), dgutierr@usb.ve D. Guti  errez-Cam- pos). 0263-4368/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII:S0263-436801)00028-2