In order to improve the corrosion resistance of the Mg alloys, the superhydrophobic coatings on AZ31 Mg alloy wereprepared by a two-step process of micro-arc oxidation treatment and superhydrophobic treatment in stear...In order to improve the corrosion resistance of the Mg alloys, the superhydrophobic coatings on AZ31 Mg alloy wereprepared by a two-step process of micro-arc oxidation treatment and superhydrophobic treatment in stearic acid ethanol solution. Theeffects of voltages, frequencies and treatment time on the contact angle of the superhydrophobic treated sample were investigated.The results showed that with increasing the voltage, frequency and treatment time, all of the contact angles of the superhydrophobictreated sample increased first, and then decreased, reaching the maximum values at 350 V, 1000 Hz and 5 min, respectively. Theoptimal superhydrophobic coating was mainly composed of MgO and Mg2SiO4 phases, with the pore diameter of ～900 nm, thethickness of ～6.86 μm and the contact angle of 156.96°. The corrosion current density of the superhydrophobic AZ31 sampledecreased by three orders of magnitude, and the amount of hydrogen evolution decreased by 94.77% compared with that of the AZ31substrate sample.展开更多
A simple and effective method of testing ablation behaviors of carbon/carbon composites at high temperature was provided, which used plasma torch as the heater. The ablation resistance of 3D fine weave pierced carbon/...A simple and effective method of testing ablation behaviors of carbon/carbon composites at high temperature was provided, which used plasma torch as the heater. The ablation resistance of 3D fine weave pierced carbon/carbon composites at high temperature was also studied. The results show that temperature of the plasma flame is very high which is much closer to the real work environment of carbon/carbon composites. The factors that affect the ablation characters of carbon/carbon composites depend on both the properties of their components and the environmental conditions in which the material is placed. The ablation behaviors of C/C composites change from the center flame region predominantly influenced by sublimation of graphite to the region close to the outer flame influenced mainly by oxidization of graphite. The sublimation ability of carbon matrix is equal to that of carbon fibers but the oxidization ability of carbon fibers is significantly enhanced compared to that of carbon matrix.展开更多
基金Project(51101085)supported by the National Natural Science Foundation of ChinaProject(2016BAB206109)supported by the Natural Science Foundation of Jiangxi Province,China+6 种基金Project(BK20151291)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(BRA2015377)supported by the 333 Project of Jiangsu Province,ChinaProject(20151BBG70039)supported by the Science and Technology Support Plan of Jiangxi Province,ChinaProject(GJJ150721)supported by the Science and Technology Project of Jiangxi Province Education Department,ChinaProject(HAG201601)supported by the Foundation of Huaian Science and Technology,ChinaProject(HAC2015026)supported by the Huaian International Cooperation Program,ChinaProject(jr1416)supported by the Foundation of Jiangsu Provincial Key Laboratory for Interventional Medical Devices,China
文摘In order to improve the corrosion resistance of the Mg alloys, the superhydrophobic coatings on AZ31 Mg alloy wereprepared by a two-step process of micro-arc oxidation treatment and superhydrophobic treatment in stearic acid ethanol solution. Theeffects of voltages, frequencies and treatment time on the contact angle of the superhydrophobic treated sample were investigated.The results showed that with increasing the voltage, frequency and treatment time, all of the contact angles of the superhydrophobictreated sample increased first, and then decreased, reaching the maximum values at 350 V, 1000 Hz and 5 min, respectively. Theoptimal superhydrophobic coating was mainly composed of MgO and Mg2SiO4 phases, with the pore diameter of ～900 nm, thethickness of ～6.86 μm and the contact angle of 156.96°. The corrosion current density of the superhydrophobic AZ31 sampledecreased by three orders of magnitude, and the amount of hydrogen evolution decreased by 94.77% compared with that of the AZ31substrate sample.
文摘A simple and effective method of testing ablation behaviors of carbon/carbon composites at high temperature was provided, which used plasma torch as the heater. The ablation resistance of 3D fine weave pierced carbon/carbon composites at high temperature was also studied. The results show that temperature of the plasma flame is very high which is much closer to the real work environment of carbon/carbon composites. The factors that affect the ablation characters of carbon/carbon composites depend on both the properties of their components and the environmental conditions in which the material is placed. The ablation behaviors of C/C composites change from the center flame region predominantly influenced by sublimation of graphite to the region close to the outer flame influenced mainly by oxidization of graphite. The sublimation ability of carbon matrix is equal to that of carbon fibers but the oxidization ability of carbon fibers is significantly enhanced compared to that of carbon matrix.
