Chromium-free Passivating Technology Based on BTA and TTA for Copper

SONG Jiu-long, CHEN Wen-ge, ZHENG Yan

Surface Technology ›› 2018, Vol. 47 ›› Issue (1) : 168-175.

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Surface Technology ›› 2018, Vol. 47 ›› Issue (1) : 168-175. DOI: 10.16490/j.cnki.issn.1001-3660.2018.01.026
Surface Failure and Protection

Chromium-free Passivating Technology Based on BTA and TTA for Copper

  • SONG Jiu-long, CHEN Wen-ge, ZHENG Yan
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Abstract

The work aims to improve corrosion resistance of pure copper surface. Pure copper was passivated by compounding benzotriazole (BTA) and methyl benzotriazole (TTA), and effects of passivation temperature, time and pH on passivation of the pure copper were analyzed. Microstructure and corrosion resistance of different passivation solutions and passivation films were studied in electrochemical method, and by performing nitric acid droplet experiment and neutral salt spray test, and using SEM, and the study results were compared with chromate passivation results. A clear and dense passivation film of better corrosion resistance formed after treatment of pure copper provided with following process parameters: 4 g/L BTA, 4 g/L TTA, 20 mL/L H2O2, pH 4, passivation time 3 min, passivation temperature 40 ℃, natural air-drying aging duration 1 day. In the salt spray test, corrosion rate of the film was low, and average corrosion rate was 0.76 mg/d, corrosion current density was only 1.5660 μA/cm2, inhibition rate was 81.9%, which was close to corrosion resistance of chromate passivation. Provided with appropriate passivation process, after the passivation by BTA and TTA, Cu/Cu2O/Cu(I)BTA polymer protective film forms on the surface of substrate. TTA non-polar methyl-forming monolayer film is more hydrophobic, both of which act together to form a more dense passivation film covering the surface of the copper substrate, thus significantly improving corrosion resistance of pure copper.

Key words

copper; passivation; BTA; chromate-free; TTA

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SONG Jiu-long, CHEN Wen-ge, ZHENG Yan. Chromium-free Passivating Technology Based on BTA and TTA for Copper[J]. Surface Technology. 2018, 47(1): 168-175

Funding

Shaanxi Provincial Key Laboratory of Education Research Project (17JS080)
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