Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology > Metal complex layer of protection

Study on Complex Surface Modification of Magnesium Alloy Via Closed Field Magnetron Sputtering Ion Platingand Nitriding

Author ZhangDanLi
Tutor ZuoMuFu
School Harbin Institute of Technology
Course Materials Science
Keywords AZ91D magnesium alloy Closed field magnetron sputter ion plating Plasma Nitriding Mechanical properties Corrosion
CLC TG174.44
Type Master's thesis
Year 2011
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In this paper AZ91D magnesium alloy surface abrasion, corrosion and poor, the first attempt by closed field unbalanced magnetron sputter ion plating technology in the magnesium alloy plating Al / Ti multilayer films, and combined plasma nitriding right its surface modification. By thermodynamic calculations, the surface of magnesium alloy composite modified intermetallic compound may be generated and the emergence of the nitride phase in the prediction; with OM, SEM, XRD, EDS and other means, and with hardness, wear resistance and corrosion Performance testing of AZ91D magnesium alloy Al / Ti multilayers were nitrided layer morphology, distribution of elements in the modified layer and the surface structure analysis, and the modified layer properties were characterized. The results show that, Al / Ti multilayer surface showing granular tissue, relatively flat, but there are few flaws; composite modified later, the sample surface with varying degrees of macroscopic folds, due to stress the role of some of the sample surface there is a clear crack, microscopic particles grow to each other to form a sheet, the density increases. Composite modified, the film appeared Al3Ti, Mg17Al12 other intermetallic compounds, and also detect some Mg, and has undergone an obvious preferred orientation. Based on cross-sectional morphology and elemental distribution, Al / Ti multilayer films showed significant multi-layered, nitriding treatment, the substrate and the film has undergone significant diffusion, diffusion of Mg element among the strongest, as the temperature increases, Mg, Al interdiffusion between the full, which results in good agreement. Microhardness test results show that the composite modified hardness of the surface of the sample nitriding temperature increases. Solution state AZ91D plated 10-layer film after 425 ℃ after 8h nitriding surface hardness up 200HV0.01, about four times before the modification. Friction and wear results indicate that the composite samples were plated infiltration modified friction coefficient did not change significantly, but after aging treatment, significantly reduced coefficient of friction, friction performance has improved. Corrosion results showed that the composite sample after the corrosion potential of the modified matrix compared with different degree, polarization curve test results and morphology show that the solution state AZ91D plated 10-layer film and nitrided at 375 ℃ after sample the best corrosion resistance. Mechanical properties and corrosion resistance results obtained, the solution state AZ91D plated 10-layer film and at 375 ℃ after nitriding specimen better overall performance.

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