Anodising of Al-Mg-Si-(Cu) Alloys Produced by R-HPDC

Abstract

Anodising of aluminium alloys can be used to improve corrosion resistance during application or it can be simply for decorative purposes. In this research, anodising of 6111 (Cu containing) and 6082 (without Cu) alloys produced by Rheo-High Pressure Die Casting (R-HPDC) was studied. R-HPDC components suffer from surface liquid segregation (SLS), the surface layer of the casting is enriched in alloying elements and it is expected to have different properties than the bulk material. An advantage of R-HPDC is that traditional wrought alloys such as the 6xxx series can be cast into near-net shape. Therefore, in order to commercialise R-HPDC of certain wrought alloy components, the anodisibility of the SLS is of importance. The two alloys, in the T6 condition, were anodised in a 250 g/l sulphuric acid solution. The anodisability of the alloys with and without SLS was studied by using a scanning electron microscope coupled with energy dispersive spectroscopy (SEM/EDS). The thickness of the sample with SLS and without the SLS was measured. The intermetallic phases in the alloys and their influence on anodising were analysed using SEM/EDS.

Influence of Si and cooling rate on microstructure and mechanical properties of Al–Si–Mg cast alloys

“…The anodized sample had an inhomogeneous color or surface appearance. The previous studies indicated that the Si acts as an undesired element for anodizing and leads to the cloudiness and darkness on the anodized surface . As shown in Figs and , after anodizing, the Si phases were still embedded in the anodized layer.…”

“…The previous studies indicated that the Si acts as an undesired element for anodizing and leads to the cloudiness and darkness on the anodized surface. [15,16] As shown in Figs 5 and 6, after anodizing, the Si phases were still embedded in the anodized layer. It seems that during the growth of the anodized layer, the oxide front grows inwards and engulfs the Si particles.…”

A Study of Anodising Behaviour of Al-Si Components Produced by Rheocasting

“…Anodising, which is an electrochemical process, is one of the most extensively used methods to improve the surface performance of aluminium alloys such as corrosion and wear resistance and aesthetic property. Previous studies have revealed that the anodised layer and its performance is strongly influenced by anodising process [2,3], surface condition [4,5], alloying elements [4,6] and microstructure [7][8][9][10].…”

“…A limited number of research have reported that the presence of SLS layer has a significantly influence on the growth of oxide layer and its performance [7,8]. Chauke et al [7] reported that the rheocast 6082 and 6111 components with SLS layer have a porous and thinner oxide layer than the components without SLS layer. Moreover, in another work by Chauke et al [8], it was found that samples with SLS layer present more corrosion attack.…”

Current Progress in Rheoforming of Wrought Aluminum Alloys: A Review

“…Therefore, besides the advances regarding the readily-available alloys, there is a strong drive to develop new and reliable alloys specifically for rheoforming for the process that take into account the process needs and the target properties concurrently. For example, there are various requirements for automotive industrial spplications, some need high strength, while some need high On the other hand, anodizing of wrought Al alloy parts can improve the surface appearance and corrosion resistance, which can be used for decorative purposes, proposing another direction for the rheoformed wrought Al alloys [131,132]. For instance, the new generation smart phones provided by the world's largest cell phone makers, such as Apple iPhone 11, HUAWEI P30 Pro, and SAMSUNG NOTE 10+, choose the wrought Al alloys as their frame due to not only lightweight and high mechanical properties, but also more choices of color.…”