CHROMIUM-FREE SURFACE TREATMENT COMPOSITION FOR GALVANIZED STEEL

摘要

PURPOSE: Provided is a chromium-free surface treatment composition for galvanized steel is provided, which does not harm to human and has good corrosion resistance. CONSTITUTION: A chromium-free surface treatment composition for galvanized steel comprises (a) at least one metal salts selected from the group consisting of colloidal silica, methoxy silane, polyvinyl alcohol, molybdate and vanadate, and (b) a balance of water, wherein colloidal silica, methoxy silane, polyvinyl alcohol are mixed in a weight ratio of 1:0.01 to 0.3:0.15 to 0.5; molybdate content in the chromium-free surface treatment composition is 0.1 to 0.8 wt.%; vanadate content in the chromium-free surface treatment composition is 0.02-0.5 wt.%.