Miao Qiang

A Comparison of Oxidation Behavior of Al Coatings Prepared by Magnetron Sputtering and Arc Ion Plating on y-TiAl

Abstract The micro-structure, the morphology and the oxidation resistance of Al coatings deposited using magnetron sputtering (MS) and arc ion plating (AIP) were investigated by means of SEM, EDS and XRD. A more compact and uniform Al coating with small grain size was deposited on γ-TiAl by MS method. A protective surface structure consisting of an oxide scale, an Al-rich layer and an interdiffusion layer was formed after oxidation test. However, the Al coatings prepared by AIP showed a poorer oxidation resistance due to the existence of a large amount of pores in the coatings, which played a role of channels for oxygen transportation and induced seriously the internal oxidation and the coating degradation finally. The non-protective scales consisting of Al2O3 and TiO2 were formed after quasi-isothermal oxidation test at 900 °C for 173 h. The results indicate that the Al coatings deposited by MS exhibit a better oxidation resistance than those by AIP.

Tribological Behavior of Plasma Mo-Alloyed Layer on TC11 Alloy under Different Loads

Abstract The tribological behavior and wear mechanism of a Mo-alloyed layer prepared by a double-glow plasma surface alloying technique were investigated under different loads. The microstructure, the composition distribution and the phase structure of the Mo-alloyed layer were characterized by SEM, EDS and XRD, respectively. The results show that the uniform and compact Mo-alloyed layer with 20 μm thickness is composed of phases Mo, Al 3 Ti and Al 8 (Ti 3- x Mo x ). The sliding wear experiments were performed under different loads (1.3, 5.3 and 9.3 N) in order to examine the tribological properties of the Mo-alloyed layer. The average friction coefficients and the wear rates of Mo-alloyed layer both show an upward tendency with the increased of loads. Mild abrasion wear and oxidative wear could be detected under 1.3 N load based on the analysis results of 3D surface morphologies, SEM and EDS. The wear mechanism under 5.3 N load is dominated by oxidative wear and abrasion wear. Oxidative wear, abrasion wear and adhesive wear are the main wear mechanism under 9.3 N.