Wear 263 (2007) 234–239 Short communication The friction and wear of various hard-face claddings for deep-hole drilling John Truhan a,∗ , Ravi Menon b , Frank LeClaire b , Jack Wallin b , Jun Qu c , Peter Blau c a University of Tennessee, Knoxville, TN, USA b Stoody Company, Bowling Green, KY, USA c Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA Received 22 August 2006; received in revised form 29 January 2007; accepted 30 January 2007 Available online 19 March 2007 Abstract Hard-face claddings are used for banding drill shafts that rotate against well casings while lubricated by drilling mud. This tribosystem should have the lowest friction possible in order to minimize drilling power requirements, and the lowest total system wear to maximize component life. Blocks representing a variety of hard-face claddings were slid against rotating rings of AISI 4140 casing material and lubricated by simulated drilling mud that consisted of a slurry of silica sand, clay, and water. The cladding specimens included currently used alloys and several candidate compositions. There was an excellent correlation between the friction coefficient and the wear, by weight loss, of both the cladding and the casing alloys. There was also a good direct correlation between the wear of the cladding and the wear of the casing. Claddings with finer grain sizes and finer, more uniformly distributed hard carbides had higher hardness and produced lower wear on both the cladding and the casing counter-face. The complex mechanisms involved with three-body wear and friction in interfaces lubricated by slurries present a challenge for further study. © 2007 Elsevier B.V. All rights reserved. Keywords: Deep-hole drilling; Slurry; Abrasion; Hard-face cladding 1. Introduction Deep-hole drilling for mining applications presents a chal- lenge in the choice of drilling materials due to the extremely harsh operating environment in which they must perform. Low wear is obviously desirable to increase shaft and casing life and reduce maintenance while low friction is desirable to reduce the energy needed for drilling. Extensive development efforts have been undertaken on hard-faced claddings for drill shafts to reduce wear and friction. However, any evaluation of the cladding alloys must also include an evaluation of the response of the counter-face, i.e., the well casing. The optimum choice of materials would be the combination producing the least wear and friction for the tribosystem. There are several industry-recognized tests for the evaluation of cladding and casing materials lubricated by a drilling “mud” slurry, but each has advantages and disadvantages. The DEA-42 Maurer Test is a proprietary test for casing wear and requires the use of large specimens. This test is difficult to perform, ∗ Corresponding author. E-mail address: Truhan John J@cat.com (J. Truhan). and consequently, is relatively expensive. The ASTM G65 dry- sand/rubber wheel test [1] and the ASTM G105 wet sand/rubber wheel test [2] for abrasion resistance are less expensive and eas- ier to carry out, but they do not allow for the influence of a metal counter-face. In previous work [3], a pin-on-disk test was used to measure the friction between various cladding alloys and AISI 4140 counter-face representative of casing material under slurry-lubricated conditions. Although a relatively simple test to conduct, the degree of wear could not be measured accu- rately due to the production of a shallow, diffuse wear scar. This was primarily due to the relatively small area of contact and the relatively large particles of silica in the slurry creating rapidly varying interfacial conditions. While, there have been numerous publications on slurry erosion and the effects of drilling mud (e.g., [4–6]), little has been published concerning the effects of abrasive slurries on friction. The current study expands on the previous work [3] by reporting a new block-on-ring procedure that enables both friction and wear measurements. Conditions were selected so that the tests could be run in a short time but produce enough wear to use weight loss as an unambiguous measure. The objectives of this study were: (1) to develop a rapid, inexpensive bench test which correlates with field experience and other 0043-1648/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2007.01.046