Papers by Author: Li Liu

Abstract: Surface potential of TC11 titanium alloy handled by beta phase (1150°C) solid solution for one hour and then taking water cooling, air cooling and furnace cooling as cold method were investigated using scanning Kelvin probe technique. The corrosion resistance difference of samples was analyzed through their surface potential. At the same time, corrosion experiments were adopted to verify it. The results show that the result of the samples corrosion resistance analyzed by scanning Kelvin probe technique is reliable and the method is feasible. Compared with water cooling sample, the corrosion resistance of furnace cooling and air cooling samples is worse and their surface potential present cathode and anode area obviously. The corrosion of furnace cooling sample is slight serious to that of air cooling sample in the early corrosion, but their corrosion resistances are almost equal. Passivation layer formed by alloy elements in the water cooling sample avails to prevent alloy from corrosion.

Abstract: The corrosion behavior and corrosion morphology of two typical TC4 titanium alloy with equiaxed structure and widmanstatten structure in hydrochloric acid solution were studied using scanning Kelvin probe techniques and observed by scanning electron microscope, respectively. The results show that along with the ongoing of corrosion, surface potential of equiaxed structure alloy is moving to positive direction and that of widmanstatten structure alloy is moving to negative direction after positive direction movement. The surface potential of two kinds structure alloy all present cathode and anode region in the corrosion process, which shows the characteristic of selective corrosion. Surface potential difference of widmanstatten structure alloy is greater than that of equiaxed structure alloy and its corrosion resistance is inferior to that of equiaxed structure alloy. Corrosion preferentially occurs in alpha phase of the two kinds structure alloy through corrosion morphology observation analysis.

Abstract: The influences of Nb₂O₅ on the phase, microstructure and hydrochloric acid corrosion behaviors of Nb₂O₅-Al₂O₃ ceramics sintered with 2.45 GHz microwave energy were investigated. The results showed that Nb2O5 reacted completely with Al₂O₃ to form AlNbO₄ and densified the pure Al₂O₃ at a lower sintering temperature and in a short sintering time. Nb₂O₅-Al₂O₃ ceramic samples were corroded in diverse concentration hydrochloric acid for different time. Weight loss rate of Nb₂O₅-Al₂O₃ ceramic rose dramatically when the corrosion time was not longer than 4 h, and it increased slowly beyond 24 h. After Nb₂O₅-Al₂O₃ ceramic samples were corroded for 1 h, pitting corrosion was observed by scanning electric microscope, which was consistent with the analysis results of the scanning Kelvin Probe.