Effects of Microstructure Modification by Friction Surfacing on Wear Behavior of Al Alloys with Different Si Contents

Abstract

In this work, Al alloys with 6.6%, 10.4%, and 14.6% Si were deposited as thick coatings by Friction Surfacing (FS), resulting in grain refinement and spheroidization of needle-shaped eutectic Si phase. Lubricated sliding wear tests were performed on a pin-on-disc tribometer using Al-Si alloys in as-cast and FS processed states as pins and 42CrMo4 steel discs. The chemical composition of the worn surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The wear mechanisms were studied by scanning electron microscopy (SEM) and focused ion beam (FIB), and the wear was evaluated by measuring the weight loss of the samples. For the hypoeutectic alloys, spheroidization of the Si phase particles in particular leads to a significant improvement in wear resistance. The needle-shaped Si phase in as-cast state fractures during the wear test and small fragments easily detach from the surface. The spherical Si phase particles in the FS state also break away from the surface, but to a smaller extent. No reduction in wear due to FS was observed for the hypereutectic alloy. Here, large bulky primary Si phase particles are already present in the as-cast state and do not change significantly during FS, providing high wear resistance in both material states. This study highlights the mechanisms and limitations of improved wear resistance of Si-rich Al alloys deposited as thick coatings by Friction Surfacing.

Post-processing ageing treatment of friction surfaced Al-16Si alloy: experimental and theoretical studies

“…The SPH method's superiority over the finite element method for simulating the FS process has been previously documented. 10 Despite the fact that there have not been many studies on the FS of aluminium-silicon alloy, 19 it is important to note that, according to Rahmati et al's research, 20 the heat treatment conditions of the consumed rod before and after the process affect the coating's properties and geometric parameters. So, the goal of this study is to find out how the rotational speed of the consumable rod affects the friction coating process of an Al-Si alloy consumable rod that has been treated with a solid solution on an AA1050 substrate.…”