Wear Resistance of Aluminum Matrix Composites’ Coatings Added on AA6082 Aluminum Alloy by Laser Cladding

Ainhoa Riquelme,Pilar Rodrigo,María Dolores Escalera-Rodriguez,Joaquin Rams

doi:10.3390/coatings12010041

Abstract

Ceramic-reinforced metal matrix composites are known for their high wear resistance. A coating based on these materials would be helpful to improve the wear behavior of aluminum alloys. Laser cladding has been used to deposit a coating consisting of an aluminum alloy reinforced with SiC particles on an AA6082 aluminum alloy. Laser cladding is a very energetic technique that causes the SiC particles to react with the molten aluminum to form Al4C3, which degrades the particles and reduces the properties of the coating. The formation of this detrimental compound was successfully achieved with the addition of Silicon and Titanium to the composite matrix. The microstructures of the newly developed material were characterized and the wear behavior was studied under dry sliding conditions on a pin-on-disc tribometer. The relationship between the microstructure and wear behavior was identified. The absence of Al4C3 in the Al40Si/SiC and Al12Si20Ti/SiC coatings’ microstructures resulted in an abrasion mechanism instead of a delamination mechanism. The wear behavior changed along the sliding distances. During the first 200 m of sliding distances, the wear rate of all coatings was lower than the uncoated one due to their higher microhardness. For longer sliding distances, the wear resistance of the uncoated AA6082 was higher than the coated ones due to the formation of a lubricant oxide layer on the AA6082 worn surface. For 1000 m of wear distances, the wear behavior was different for each coating. The wear rate of the Al12Si/SiC coating continued growing due to the delamination mechanism and the presence of Al4C3 that acted as starting crack points. The wear rate of the Al40Si/SiC coating decreased due to the formation of a thin, superficial oxide layer. The wear rate of the Al12SiTi/SiC progressively decreased along the sliding distance to below the substrate wear rate.

Highlights

Nowadays, the growth of social ecological awareness highlights the search of lightweight materials in order to obtain the weight reduction of the components used in the aerospace and automobile sectors, which is considered a priority in these sectors
The present study focused on developing a methodology to deposit aluminum matrix composites reinforced with SiC particles (Al/SiC) on AA6082 alloy, avoiding the degradation of the SiCp and the formation of aluminum carbide by modifying the matrix used with Si or Ti
For longer sliding distances (500 m), the wear resistance of the uncoated AA6082 was higher than the coated ones due to the formation of a lubricant oxide layer on the AA6082 worn surface

Summary

Introduction

The growth of social ecological awareness highlights the search of lightweight materials in order to obtain the weight reduction of the components used in the aerospace and automobile sectors, which is considered a priority in these sectors. The lightest metals’ applications are limited due to their low mechanical properties. The development of new materials with improved properties is mandatory [1,2,3]. Surface engineering could provide solutions and increase the applications of these alloys. In this sense, the possibility of manufacturing coatings of metal matrix composites on aluminum alloys has been extensively researched [4,5,6]. A reference material due to their favorable mechanical properties is the aluminum matrix composites reinforced with SiC particles (Al/SiC) because the integration of a ceramic phase into a matrix can enhance their mechanical properties [7,8]

Methods

Results

Conclusion