The Modification Of OP10 Of The Corrosion Resistant Of Vanadate Conversion Coating On Mg Alloy

Mg alloys,which have a low density,high strength,good casting performance,good thermal and electrical conductivity,etc.,are widely used in aerospace,automotive,3C and other fields.However,due to corrosion,its application is limited.So,it is very important to prevent the corrosion of Mg alloys.Chromate conversion technology with its low cost and superior corrosion resistance has been one of the most widely used methods for metal surface treatment.But because of its carcinogenicity,it has been banned from use.The development of chromium-free conversion coating technology for Mg alloy instead of using the traditional chromate process has become an important problem to be solved urgently.Ammonium metavanadate conversion coating,which was modified by sodium dodecyl benzene sulfonate(SDBS)in our previous research,could significantly improve its corrosion resistance and the salt spray time was up to 72 h.But in the process of the reaction,a defective conversion coating was obtained due to the bubbles attachment on Mg alloy surface.Therefore,Mg alloy surface is prone to pit,affecting the improvement of the corrosion resistance of Mg alloys.Aimed at the problem this paper used non-ionic surfactant OP10 to increase the wettability of the conversion solution and the corrosion resistance of the coating,The results show that under the condition of 2.2 g/L NaVO3,1.2 g/L SDBS,0.6 mL/L OP10,pH 2.5,15 min and 30 ?,the neutral salt spray time of the prepared coating increased from 72 h to 140 h compared with that without the addition of OP10.After OP10 addition,the contact angle of the conversion coating was decreased,its V,O,S elemental content and SDBS characteristic peak area was increased.The research results showed that in the NaVO3 and SDBS conversion solution,the higher wettability of Mg alloy due to the addition of nonionic surfactant OP10 leads to(1)Bubbles are difficult to adhere to Mg alloy surface;(2)Adsorption of SDBS on Mg alloy surface is more sufficient.Therefore,the conversion coating is more perfect and the corrosion resistance of Mg alloy is greatly enhanced.