Wear Resistance Enhancement of Al6061 Alloy Surface Layer by Laser Dispersed Carbide Powders

In this paper, results of the experimental study on improving wear resistance in sliding friction of Al-based alloy are presented. The technique used involves the formation of a metal matrix composite (MMC) in the alloy surface layer by laser dispersion of carbide powders such as WC, TiC and SiC. For WC and TiC MMC surface coatings fabricated under conditions typical for most of the technologically relevant solid-state lasers (wavelength range of 0.8–1.1 μm), the nearly inversely proportional dependence of the required laser energy density on the powder mass density is observed. Highly homogenous distribution of powder particle content (up to 40%) in the MMC surface coatings of a thickness between 0.8 and 1.6 mm obtained by multiple scanning is observed in the cross-section of specimens processed within a rather narrow parameter window. Tribological tests and comparison to untreated material reveal wear resistance increases by five- and ten-fold, observed in samples with laser-dispersed TiC and WC powders, respectively. Results indicate that substantial modification and reinforcement of the surface layer can be achieved in Al alloy in a one-step process without substrate preheating.

Modification of Ti6Al4V Titanium Alloy Surface Layer in the Ozone Atmosphere

The paper reports the results of a study on the Ti6Al4V titanium alloy involving the XPS (X-ray photoelectron spectroscopy) photoelectron spectroscopy method. The position of bands in the viewing spectrum serves as a basis for the qualitative identification of atoms forming the surface layer, while their intensity is used to calculate the aggregate concentration of these atoms in the analyzed layer. High-resolution spectra are used to determine the type of chemical bonds based on characteristic numerical values of the chemical shift. The paper also presents the 3D results of surface roughness measurements obtained from optical profiling, as well as the results of energy state measurements of the Ti6Al4V titanium alloy surface layer after ozone treatment. It was shown that the ozone treatment of the Ti6Al4V titanium alloy removes carbon and increases concentrations of Ti and V ions at higher oxidation states at the expense of metal atoms and lower valence ions. The modification of the surface layer in ozone atmosphere caused a 30% increase in the Ti element concentration in the surface layer compared to the samples prior to ozone treatment. The carbon removal rate from the Ti6Al4V titanium alloy samples amounted to 35%, and a 13% increase was noted in oxides. The tests proved that the value of the surface free energy of the Ti6Al4V titanium alloy increased as a result of ozone treatment. The highest increase in the surface free energy was observed for Variant 4 samples, and amounted to 17% compared to the untreated samples, while the lowest increase was equal to 14%. For the analyzed data, the maximum value of standard deviation was 0.99 [mJ/m2].

Device of magnesium alloy grinding using periodic cleaning of the active surface of grinding wheel during machining

In the paper the range of requirements concerning grinded surface layers for deposition of protective PVD coatings on magnesium alloys has been presented. Also difficulties concerning the preparation of surface layer and literature review have been depicted. For solving of the problems concerning proper preparation of magnesium alloy surface layer the conventional grinding process using ceramic grinding wheels and the process of cleaning of CSGW during machining has been applied. The machining parameters has been determined and the surface geometrical structure has been assessed using optical profiling in 3D configuration.

Tribological properties of aluminium alloy surface layer after finishing treatments

Investigation’s results of the surface geometric structure and tribological properties of the aluminum alloy EN AW-AlCu4MgSi(A) processed by various finishing treatments: grinding, polishing and ball burnishing are presented in the paper. The test of abrasive resistance and friction coefficient determination was carried out by usage of the T-01M tester. The tests were carried out under dry friction conditions using the ball-on-disc method. As a counter-sample, a polished Al2O3 ceramic ball with a diameter of 6 mm was used. After burnishing, comparing to grinding and polishing, an approximate twice reduction of the volume wear rate was obtained. Depending on the type of surface treatment mean friction coefficients are 0.45 after grinding, 0.34 after polishing and 0.32 after ball burnishing.

DESTRUCTION OF BLADES SURFACE COATING

The article discusses a change of impact elasticity (a crack resistance or other value characterizing a resistance to rupture) depending on the cutting blade heating temperature. The test results showed that high temperature impact resistance strengthening of the hard alloy blade structure by treatment of its surface with wearresistant refractory titanium nitride coating proved its effectiveness at 500 0C and at 600 0C. At temperature of 900 0C a deterioration occurs resulted from generation of defects in the coating and in the hard alloy surface layer which become the sites of destructive impact crack initiation.

Structural Aspects of Remelting of the AZ91 Magnesium Alloy Surface Layer

In this study, modification of the AZ91 magnesium alloy surface layer with a CO2 continuous wave operation laser has been taken on. The extent and character of structural changes generated in the surface layer of the material was being assessed on the basis of both macro- and microscopy investigations, and the EDX analysis. Considerable changes in the structure of the AZ91 alloy surface layer and the morphology of phases have been found. The remelting processing was accompanied by a strong refinement of the structure and a more uniform distribution of individual phases. The conducted investigations showed that the remelting zone dimensions are a result of the process parameters, and that they can be controlled by an appropriate combination of basic remelting parameters, i.e. the laser power, the distance from the sample surface, and the scanning rate. The investigations and the obtained results revealed the possibility of an effective modification of the AZ91 magnesium alloy surface layer in the process of remelting carried out with a CO2 laser beam.

Tribological Properties of (EN AW-AlCu4MgSi(A)) Aluminium Alloy Surface Layer After Ball Burnishing

EN AW-AlCu4MgSi(A) aluminium alloy is widely used as a structural material in aerospace and automotive applications. We have subjected it to grinding, polishing and ball burnishing. We have performed ball-on-disk tribological tests. We have also determined normalized 3D roughness parameters. High surface smoothness turns out to be obtainable. Favorable effect of the ball burnishing on the tribological properties of the alloy are seen. Results will be presented at the Conference.