Wear Properties of an In-Situ Processed TiC-Reinforced Bronze
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Wear Properties of an In-Situ Processed TiC-Reinforced Bronze R. Sanchez and H. F. Lopez Materials Department, University of Wisconsin-Milwaukee, Milwaukee WI 53209. ABSTRACT In this work, an Al-bronze alloy is reinforced with TiC through reaction of the alloy melt with methane gas. The resultant alloy is then centrifugally cast in cylindrical molds. It is found that the surface at the inner diameter of the cast contained in-situ produced TiC as well as Fe-rich inclusions. Metallographic observations using optical and scanning electron microscopy confirmed the presence of TiC particles (30 % volume), alpha and beta grains including iron precipitates. Cylindrical pins are machined from the inner surface and tested under various conditions in a three pin on disk Falex machine. Pins are tested under a constant load of 2.86 MPa and friction and wear rates are determined from measurements of weight losses versus wear lengths. It is found that under the applied load the reinforced material exhibits high friction and relatively low wear when compared with the unreinforced material. Apparently, under these conditions the TiC particles become abrasive particles thus contributing to wear of the steel counter-face through three body abrasive wear. INTRODUCTION Aluminum bronzes are copper-base alloys in which up to 14% Al is added as the main alloying element. Smaller additions of nickel, iron manganese and silicon are often introduced to meet different requirements of strength, ductility and corrosion resistance [1,3]. In particular, they exhibit good corrosion resistance in sea water and relatively high strengths. In these alloys, Al has a marked effect on the corrosion properties through the formation of an aluminum oxide layer which seals the core alloy from any further corrosive reactions [4]. However, the wear resistance of conventional Al-bronzes is not always the one required for marine applications such as anti-slake devices and hauling winches [5]. Asbestos and lead are the typical materials used for these types of devices. Nevertheless, these materials are currently unacceptable due to their toxicity and damage to the environment. Hence, TiC reinforced Albronzes have been considered as an attractive alternative for the there manufacture of these components. Among the manufacturing methods considered is the Reactive Gas Injection method (RGI [5]. The RGI method is based on the “in-situ” processing of carbide reinforced Cu alloys [6]. In this process, CH4 is injected into the Al-Cu-melt where an “in-situ” reaction with a purposely added solute (Ti) gives rise to a distribution of TiC particles within the bronze matrix. Thermodynamically, the process is highly stable and the interfaces developed between matrix and reinforcement are tightly bonded. This is in contrast with other conventional processes where, the reinforcement particles are introduced by external means. The objective of the present work is to investigate the wear and friction resistance of an “in-situ” TiC-Al-bronze composite processed by centrifugal cast
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