Method for treating thick protective layer on surface of AZ91 magnesium alloy

Abstract

The invention discloses a method for treating a thick protective layer on the surface of an AZ91 magnesium alloy, which belongs to the field of treatment and research of thick protective layers on surfaces of AZ91 magnesium alloys. The method comprises the following steps of: introducing oxygen into treating fluid on the basis of an alternating current plasma microarc oxidation treatment method so as to enhance and improve the sintering effect on the protective layer; and performing alternating current plasma microarc oxidation surface treatment on the AZ91 magnesium alloy for 94 to 120 seconds under the conditions that the concentration of potassium fluoride is 837 to 839 g / L, the concentration of potassium hydroxide is 296 to 298 g / L, the concentration of sodium silicate is 91 to 93 g / L, power frequency alternating current voltage is 108 to 110 V and oxygen introduction amount in each liter of treating fluid is 0.006 to 0.008 L / s so as to form a uniform thick protective layer with compact tissues and the thickness of between 55 and 65 micrometers on the surface of the AZ91 magnesium alloy.

Description

technical field [0001] The invention relates to a method for treating a thick protective layer on the surface of an AZ91 magnesium alloy. Background technique [0002] Publication number: CN1900383A, title of invention: "A Surface Treatment Method for AZ91 Magnesium Alloy", expounded the AC plasma micro-arc oxidation treatment method for AZ91 magnesium alloy, that is, using a treatment solution containing potassium fluoride and potassium hydroxide, by The power frequency AC power supply controlled by the voltage regulator provides electric energy. In each power frequency AC voltage cycle, the instantaneous high temperature generated by the plasma micro-arc discharge on the surface of the AZ91 magnesium alloy is generated by using the negative and positive ions in the treatment liquid. Form a protective layer. Using this AC plasma micro-arc oxidation treatment method, the concentration of potassium fluoride disclosed in the patent CN1900383A is 500-979g / L, the concentration ...

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Problems solved by technology

However, the thick layer with a thickness of more than 30 μm formed on the surface of the AZ91 magnesium alloy by the CN1900383A patent method has a relatively serious sandification phenomenon, that is, the protective layer becomes loose and pills. There is almost no protective effect on the magnesium alloy substrate, that is to say, the maximum thickness of the protective protective layer formed on the surface of the AZ91 magnesium alloy by the CN1900383A patent method is 30 μm

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