Dry Sliding Behavior of an Aluminum Alloy after Innovative Hard Anodizing Treatments

Abstract

This work evaluates the dry sliding behavior of anodic aluminum oxides (AAO) formed during one traditional hard anodizing treatment (HA) and two golden hard anodizing treatments (named G and GP, respectively) on a EN AW-6060 aluminum alloy. Three different thicknesses of AAO layers were selected: 25, 50, and 100 μm. Prior to wear tests, microstructure and mechanical properties were determined by scanning electron microscopy (VPSEM/EDS), X-ray diffractometry, diffuse reflectance infrared Fourier transform (DRIFT-FTIR) spectroscopy, roughness, microhardness, and scratch tests. Wear tests were carried out by a pin-on-disc tribometer using a steel disc as the counterpart material. The friction coefficient was provided by the equipment. Anodized pins were weighed before and after tests to assess the wear rate. Worn surfaces were analyzed by VPSEM/EDS and DRITF-FTIR. Based on the results, the GP-treated surfaces with a thickness of 50 μm exhibit the lowest friction coefficients and wear rates. In any case, a tribofilm is observed on the wear tracks. During sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and to abrasion of the aluminum substrate. Finally, the best tribological performance of G- and GP-treated surfaces may be related to the existence of a thin Ag-rich film at the coating/aluminum substrate interfaces.

Abrasive Wear Resistance and Tribological Characteristics of Pulsed Hard Anodized Layers on Aluminum Alloy 1011 in Tribocontact with Steel and Ceramics in Various Lubricants

“…Both of these factors contributed to the separation of small areas of the PHAL surface from the inner sublayer, followed by the adhesion of gibbite particles to the surface of the ceramic ball. Similar wear patterns during friction tests of anodized layers were observed by other researchers [67,68]. The proposed mechanism of PHAL wear is also confirmed by the results of X-ray microspectral analysis of the surface layer on the ceramic ball after its contact in air with PHAL, synthesized at a temperature of +10 • C (Figure 24).…”

“…The presence of sulfur on the contact surface of this ball with the PHAL layer (spectrum in Figure 24b) indicates the transfer of the surface layer of PHAL and its adhesion to the ceramic surface. during friction tests of anodized layers were observed by other researchers [67,68]. The proposed mechanism of PHAL wear is also confirmed by the results of X-ray microspectral analysis of the surface layer on the ceramic ball after its contact in air with PHAL, synthesized at a temperature of +10 °C (Figure 24).…”

Tribocorrosion Characteristics of Hard Anodized Al Alloys on Hydrogen Valve Application for Fuel Cell Electric Vehicles

“…[ 54 ] Similarly, the tribofilm formed on the surface of the hard anodized specimens decreased the friction coefficients. [ 55,56 ] However, due to the relatively high hardness of the hard anodized layer (800 HV), wear in the counter‐body (1600 HV) and the hard anodized specimen occurred simultaneously, thus increasing the surface roughness of the counter‐body and disk (hard anodized specimen). In addition, it is believed that due to brittleness, a large amount of the debris and asperities were formed by friction/wear, resulting in a relatively large friction coefficient.…”

In Situ Growth of High-Performance ZnAl-Layered Double Hydroxides/Al2O3 Composite Coatings on Aluminum Alloy

“…Therein, the wear loss of the sample with the Zn 2+ co centration of 0.30 mol/L is the lowest (0.20 mg), which is caused by the lower average CO and larger interfacial bonding strength. Additionally, the published literature also fou that the thickness and pore size of the AAO coatings has an effect on the tribological b havior to a certain degree [50,51]. As a result, the AAO parameters and LDH nanoshe may have a coupling impact on the friction and wear performance of ZnAl-LDHs/AA composite coatings.…”