| Magnesium alloy as a new kind of structural materials was more and more valuedsince the new century, It compared with other structural metal material has stronger thanstrength, stiffness, and damping properties, electromagnetic shielding, and radiationresistance，so it has been widely used in cars, planes, and electronic products. Butmagnesium alloys are highly susceptible to corrosion damage of the outside world,especially in some parts of the coast of our country has a Marine climate can accelerate thecorrosion of magnesium alloys, which leads to magnesium alloys is limited by the strictapplication field. Refused to complete statistics, every year because of magnesium alloycorrosion damage accounted for about0.5%~1.2%of GDP in our country.Although thereare a lot of research magnesium alloy corrosion protection method at present and but eachmethod has its disadvantages. Research, therefore, a kind of both simple and effective andenvironmentally friendly magnesium alloy corrosion method has important practicalsignificance.At present, magnesium alloy corrosion methods commonly used are mainlymetallurgical refining, chemical process, chemical plating membrane, anodic oxidationmethod, gas phase deposition, etc. But each kind of the use of anti-corrosion methods havesome limitations, this leads to a magnesium alloy corrosion research and development isrelatively lagging. Among them, the metallurgy purification process more difficult tocontrol, and cost is high; Chemical conversion coating method can effective for corrosionprotection of magnesium alloys, but the produce of heavy metal ions can cause pollution tothe environment; Electroless plating method for chemical membrane process on theenvironment pollution is small, but the poor mechanical properties, chemical coating layeris easy to knock against damage; And anodic oxidation method to shape simple parts canhave antiseptic effect, but for some complex shape parts can be hard to form uniform filmlayer on the surface, not on the anti-corrosion; Chemical vapor deposition technique is anew development of technology, it combines some of the above methods, no matter simpleor complicated workpieces can form various kinds of compound film, greatly enhance thesurface anti-corrosion performance, and less pollution to the environment.In this paper, sputtering TiN thin film and TiNC that the type of ceramic membranelayer in MB7type magnesium alloy surface by magnetron sputtering method to studied thetwo membrane layer on the surface of magnesium alloy corrosion resistance. Through orthogonal test analysis, the target5kw power, bias voltage150v, duty ratio80%,3.0x10-1the parameters of the vacuum, the nitrogen uptake of18and60min coating time,coating temperature of180℃under the condition of TiN film layer, and the depositiontime is10min,15SCCM nitrogen, methane15SCCM conditions of class ceramic TiNCcomposite membrane layer by4h salt spray corrosion test, found that the two kinds ofcoating on the magnesium alloy has good anti-corrosion performance, and corrosionresistant rating can achieve grade9. Based on TiN coating adhesion test, the result showthat TiN and the magnesium substrate has strong binding force. By using interferencemicroscope measure film thickness of the two coatings is higher than the other parametersof the membrane layer. The TiN film thickness and deposition time was positively thanbasic changes, and relatively small temperature influence on the film thickness. For TiNCfilm layer, the film thickness is affected by the methane flow and nitrogen flow at the sametime. Both relative to the nitrogen excess methane, and its relative to the excess methane,coating thickness will decrease, thus influence the effect of coating on magnesium alloycorrosion.For specific research TiN and TiNC membrane layer on the substrate’s corrosionresistance, in this paper, we do the chemical polarization comparison test. Through its andthe magnesium alloy substrate in a5%NaCl aqueous solution electrolytic corrosion incomparison, the results found the TiN and TiNC membrane layer corrosion lower thepotential of magnesium alloy matrix significantly, and the corrosion rate of TiN, about2.2times higher than that of the magnesium alloy substrate, TiNC was4.4times greater thanthat of the substrate. |
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