Enhancement of Wear Resistance of Copper With Tungsten Addition (≤20 wt %) by Powder Metallurgy Route

Abstract

Copper–tungsten composite materials are developed for applications such as electrical contacts, resistance electrodes, and contact tips in welding guns as well as for components requiring higher wear resistance. In addition to the aspect of improved performance, it is scientifically interesting to assess the tribological properties, and therefore the objectives of the present work include, to determine the role of W additions in improving the fretting wear resistance of Cu for electrical applications, to determine the optimum concentration for W additions, and to identify the mechanisms responsible for fretting wear improvements. In addressing these issues, a planned set of fretting wear tests were conducted on powder metallurgically processed Cu–W composites (maximum W content of 20 wt %) against steel counterbody under varying load (up to 10 N) for 10,000 cycles. It has been observed that at lower loads of 2 N, the coefficient of friction (COF) recorded was ∼0.9 for the Cu–20 wt % W/steel, whereas it was ∼0.85 for a pure Cu/steel couple. Under similar operating conditions with the increase in load, the COF decreases to 0.5 at 10 N load, irrespective of the composition of the Cu–W composite. Furthermore, the incorporation of 5 wt % W has reduced the volumetric wear loss by 4–6 folds in comparison to unreinforced Cu. The addition of even higher percentage of W has led to increase its wear resistance by ∼10 folds. Under the investigated conditions, the wear rate systematically decreases with the increase in load for all the tested Cu–W composites. Based on the topographical observation of worn surfaces, it is observed that wear mechanisms for the Cu and Cu–W composites are tribochemical wear, adhesive wear, and abrasive wear. The incorporation of harder W particles (5 wt % or more) help in abrading the steel ball and in forming a dense tribolayer of FexOy, which effectively reduces wear rate and hence, increases wear resistance of the Cu–W composite surface in reference to unreinforced Cu.

Characterization, pore size measurement and wear model of a sintered Cu–W nano composite using radial basis functional neural network

“…Wear resistance is an important factor for various engineering applications for the better performances. Although the friction and wear properties of the Cu based composites in dry sliding wear conditions are widely investigated, such understanding in Cu-W compacts are very limited [1,2,12].…”

“…The Cu matrix composites benefit from the wear resistance of the reinforcement such as W, due to some other good ceramic reinforcement components. W is well known for its better wettability and improved tribological property without affecting the electrical conductivity of Cu, due to its very high melting point [1]. Copper-tungsten (Cu-W) composites are extensively used for their superior strength at high temperature and wear resistance, for electrical discharge, electrode materials, relay blades and electrical contact supports [2].…”

“…The P/M processing includes mixing, pressing and sintering [3][4]. One of the advantages of P/M when compared to casting is having better control on the microstructure and better distribution of the reinforcement is possible in P/M compacts, but P/M processed composite always have pores [1,5]. In conventional sintering, an external source of heat and radiation are used to heat green compacts [6][7].…”

Electrochemical Behavior of Cu-MWCNT Nanocomposites Manufactured by Powder Technology

“…MMCs are produced via the addition of a reinforcement phase into a matrix using a well-established technique such as powder metallurgy (PM), squeeze casting, and liquid metallurgy [12]. The PM technique is extensively used for the production of Cu-W composite materials in which wear behavior is the main issue that was extensively studied [13]. Reinforcements with nano-sized particles and/or fibers have received considerable attention due to the significant improvement that may be obtained in the mechanical and physical properties of the metal matrix compared to that of micron-sized reinforcements.…”

Investigation and characterization of Copper-Fly ash-Tungsten hybrid composites synthesized through P/M process

“…The most common techniques used are solid phase processing and liquid phase processing. Though liquid phase processing (casting) is suitable for mass production, it has certain disadvantages such as the non-uniform distribution of reinforcements, the reaction of reinforcement with the matrix phase, the formation of oxides and the segregation of reinforcement etc, [27]. In this study, the Powder metallurgy process was used for the fabrication of preforms and uniform distribution of reinforcement was achieved.…”