Papers by Keyword: Phosphate Coating

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Authors: Juch Kuang
Abstract: It had validated by experiments why appending rare earth nitrate (REN) into the bath affects notably on development of coating-forming, corrosion resistance as well as on urgency varieties of appearance and component of the coating. The causation rests with the fact that REN not only makes metal surface depolarized and cathodic reactions accelerated, but also acts as crystal nucleus with gel forms on the metal surface to speed up the coating-forming and develop the anti-corrosion capacity of the coating. The optimal level of addition of REN is 30-55 mg·L-1.
Authors: Guang Ling Song
Abstract: The corrosion resistance of phosphated Mg components is very low. A low cost and high corrosion resistant sealing technique is particularly desired. In this study, a new sealing technique was proposed and validated in laboratory trials. Phosphated AZ91D was simply dipped in an E-coating bath solution for a few seconds. After baking, the specimens were found to have considerably improved corrosion resistance.
Authors: Juch Kuang
Abstract: Experimental results show that the samples gained in bath added Rare earth nitrate (REN), relative to the sample got in bath without REN, improve the anti-corrosion power of the coating because of increasing of covering rate of formless crystal Zn2Fe(PO4)2·4H2O (marked P) crystals and the ratio of P/(P+H) (H is the mark of Zn3(PO4)2 crystal) in the coating, combination of which with components parsing by EDS indicates that the sequence of contribution elements P and Zn to erosion resistance of coatings is P>Zn. And the correlative mechanism was discussed, which has it clear that RE is materially a catalyst holding excellent ability of carrying oxygen and cathode depolarization, its concentration gets so constant in certain range that it is much steadier and more efficient than the usual consumptive oxidants like nitrates. In a word, REN plays the role of surface regulator, accelerant and densification agent, which speeds up the phosphating, and bids it effective to enhance the anti-corrosion power of the coating. The addition of REN, not only promote the phosphating film formation and substantial reduction or exemption of nitrite. So, REN is green phosphating accelerator of live up to one's name.
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