Preparation And Corrosion Resistance Of Methyl Benzotriazole/Cetylpyridinium Bromide Composite Passivation Film On Copper Alloys

Copper alloys are widely used in the preparation of electronics,construction,packaging,imitation gold,etc.due to their excellent electrical conductivity,corrosion resistance,aesthetics and decorative properties,as well as affinity,chemical properties and stability with other elements.Various products.Like other metals,copper alloys are also subject to corrosion problems in practical applications.Passivation is one of the most simple and effective methods for many copper alloy protection methods.The current copper alloy passivation in industrial production is still dominated by chromate.However,chromate is carcinogenic and pollutes the environment and has been restricted.Therefore,the development of a new environmentally friendly chromium-free passivation process has important practical and economic value.Based on the previous study of benzotriazole(BTA)passivation film on copper alloy surface,a single passivation of methylbenzotriazole(TTA)and composite passivation of Cetylpyridinium bromide(CPB)were studied.(1)The results of single TTA passivation show that the passivation film prepared in the passivation solution containing 2.5g/L TTA has certain resistance at p H 5.0,reaction temperature 70 °C and reaction time of 16 minutes.The salt spray resistance time of the copper alloy samples was extended from 4 h before passivation to 20 h.The passivation film corrosion potential was shifted by 36 m V,the corrosion current density was reduced by 86%,and the electrochemical impedance value was increased by 33 times.The TTA passivation film is uniform and dense.the contact angle is 90.44°,and it hasgood hydrophobicity.The composition and content of the film layer are mainly Cu61.32%,Zn 38.07%,C 0.22%,N 0.36%,O 0.22%.The results of CPB and TTA compounding passivation showed that the composite blunt prepared in the passivation solution containing 2.5g/L TTA and 0.5g/L CPB under the conditions of p H 5.0,reaction temperature 75 °C and reaction time 16 minutes.The corrosion resistance of the film is obviously enhanced.The salt spray resistance time of the copper alloy samples was extended from 4 h before passivation to 48 h.The corrosion potential of the passivation film was shifted by 65 m V,the corrosion current density was reduced by 95%,and the electrochemical impedance value was increased by 78 times.The passivation film is more uniform and dense,the contact angle is 82.96°,and it also has good hydrophobicity.The element composition and content of the film are mainly Cu 58.61%,Zn 38.99%,C 0.89%,N 1.17%,O 0.34%,Br 0.14.%,in which the elemental content of C,N,and Br is increased.