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White powder defect on Black Passivation on Acid Zinc Plating

2006

We are facing a problem of white powder developing on Hexavalent black passivation on zinc plated components. The problem occurs only during monsoon season when their is moisture in air.

Kindly help,

Vinod Kakar
Pervesh Rasayan - Faridabad, Haryana, India

2006

It could be Zinc Oxide (ZnO). Normally zinc would oxidise at temperatures above 400 °C. But maybe with the exposure of moisture and catalysts, oxidation is possible. Find ways to avoid contact with moisture.

Shahrom Mahmud
Univ of Science - Penang, Malaysia

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