engleski

Electroless Ni–P deposition on AZ91D magnesium alloy prepared by dodecylphosphonic acid pretreatment coating

Magnesium and its alloys, with one quarter of the density of steel and only two-thirds that of aluminium and a strength to weight ratio that far exceeds either of these, fulfill the role admirably as an ‘ultra light weight’ alloy. Therefore, magnesium alloy parts are used in a variety of applications, such as in automotive and aerospace equipment. Though magnesium has excellent properties, the high chemical reactivity results poor corrosion resistance. One of the most effective ways to prevent corrosion is to coat them. Among the various coating techniques the electroless nickel plating is of special interest. Electroless plating of magnesium alloy needs special bath formulations and pre-treatment procedure due to the microstructural heterogeneity. In the present work, a dodecylphosphonic acid was proposed as the pretreatment coating between Ni–P coating and AZ91D magnesium alloy substrate. The silane coupling agent was adopted as connector between pretreatment films and palladium ion with catalysis. Then, the electroless Ni–P deposition on the pretreatment coating was undertaken by using the plating bath. Electrochemical behavior of the unmodified and modified magnesium AZ91D alloy substrate were analyzed by EIS and voltammetry methods, while the microstructure of the films was observed using analytical surface methods..

magnesium; electroless; nickel plating; pretreatment coating; silane

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