Abstract
Laser composite surfacing of aluminum alloys with ceramic particles has been extensively investigated for improving tribological properties. However, the process often results in incomplete penetration of ceramic particles in the melt pool and undesirable interfacial reactions. In this paper, laser composite surfacing of 2024 aluminum alloy with SiC particles is investigated using two distinct approaches: laser remelting and laser melting under the influence of ultrasonic vibrations of preplaced powder mixture. Detailed analysis of variation of clad layer thickness, microstructure in the composite clad layer, phase/texture development, surface roughness, and sliding wear performance with laser processing conditions is presented. The analysis showed that remelting and ultrasonic vibration assist results in significant improvement in clad layer thickness and microstructure (reduction in needle-like α-Si phase). While the laser remelting resulted in significant reduction in wear rate, the specimens processed with ultrasonic vibration-assisted laser melting showed variable wear rate, likely due to complex effects of microstructural modification and enhanced surface roughness.
Highlights
Aluminum alloys have gained rapid popularity in the last few decades—especially in automobile and aerospace industries—due to their easy availability, high strength-to-weight ratio, excellent corrosion resistance, and appreciable formability
It appears that similar effects cause deeper penetration of ceramic particles in the melt pool during laser composite surfacing, resulting in thicker clad layer thickness and improved C/I ratio in specimens laser melted and remelted with simultaneous assistance of ultrasonic vibrations
The results indicate that laser remelting, both with and without simultaneous application of ultrasonic vibrations, results in slightly higher texturing compared to laser specimens
Summary
Aluminum alloys have gained rapid popularity in the last few decades—especially in automobile and aerospace industries—due to their easy availability, high strength-to-weight ratio, excellent corrosion resistance, and appreciable formability. These alloys are often reported to exhibit inadequate surface properties such as wear and corrosion resistance, and are often required to be replaced frequently [1]. The success of laser processing techniques in such technologies has been associated with non-contact processing, superior control during the processing, and short processing time [4] These features, have been the key for the promising results that include the ability to form comparatively thick coatings (as thick as 1.5 mm), metallurgical bonding between the cladded surface and bulk, and relatively small heat affected zones [5]
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