No abstract

This study aims to resolve the wear resistance and extend the use of titanium aluminides. A novel method of obtaining multiphase films bearing Ti 2 AlN on the Ti-Al alloys is put forward. The Ti 12x Al x (x50?25, 0?33 and 0?47) alloys were nitrided in a pulse plasma hollow cathode environment at 800-900uC for various durations in a mixture of 50%N 2 and 50%H 2 under pressures of 1?50-3?00 torr. The results show that the nitriding gas pressure has a strong influence on the phase structure of the surface films. The forming phases in the films are mainly composed of Ti 2 AlN and TiN compounds. The presence of Ti 2 AlN in the wear tracks apparently reduces the friction coefficient of the samples. The hardened phase TiN in the film improves the wear resistance of the Ti-33Al alloy.

The corrosion performance of Sn-0.7Cu solder alloy is investigated in 1 M Hydrochloride acid by means of potentiodynamic polarization technique at the scan range of -2VSCE to 1 VSCE was applied to the sample at the scan rate of 1mV/s. Supporting morphological analysis was done by using Scanning Electron Microscope while phase analysis was confirmed by using X-ray Diffraction analysis. Morphological analysis showed two type of oxide layer has formed as corrosion product, which are compact oxide layer and loose rod-like oxide layer after corrosion analysis which confirmed to be SnO and SnO2. This indicate that complete protection from further corrosion was impossible due to the incomplete passivation layer formation.

Study on different characteristics of TanRai aluminum hydroxide dissolution process in acid and base media were carried out on unactivated and activated samples using 3000rpm centrifugal grinding method under other conditions. The experimental results showed that the centrifugal grinding process did not change the solid phase structure (Gibbsite), and the specific surface of the sample was increased by 1.5 times, average particle size was increased by 10 times, the surface morphology during process of TanRai aluminum hydroxide dissolution were different. In the case of the process of Al(OH)3 dissolution in NaOH media, the corrosion reaction occurs on the all surface of the particle. It goes deep and accesses into the particle. The specific surface might be increased by 10 times in reaction processing, so the grinding did not increase recovery efficiency. In case of dissolution Al(OH)3 in HCl media, the reaction occurs on surface particle so the grinding effects to dissolution recovery that increasing from 2 to 5 times.