Contaminação da superficie do aço-carbono zincado por imersão a quente com sais solúveis provenientes do processo de zincagem

Abstract:

In the process of hot-dip galvanizing of carbon steel, the use of hydrochloric acid (HCl) acid in pickling of zinc
double salt of ammonium chloride (ZnCl ². NH.CI) in the fluxing bath and solid ammonium chloride (NH CI) written on galvanized parts when they are withdrawn from the bath of molten zinc, are possible sources of contamination soluble salts of chloride on the surface of the zinc coating. In the work, carbon steel plates were plated in five service providers hot dip galvanization, which were coded A, B, C, D and E, in two different conditions: with and without the use of NH CI , solid cast on galvanized parts during their withdrawal from the bath of molten zinc. After the process of galvanizing, assays were performed to quantify chloride on the surface of the zinc coating. According to the test results of extraction with boiling water held in galvanized sheet metal, it is concluded that plates produced in different service providers may have surface contamination by chloride salts in different degrees, and further application of NH CI solids during the galvanizing process may increase the level of contamination. The steps of chromating and / or cooling process after galvanizing, also exert significant influences on the degree of contamination of the surface.


Reference:
PANOSSIAN, Z.; FERRARI, J.V.; FRAGATA, F.L. Contaminação da superfície do aço carbono zincado por imersão a quente com sais solúveis provenientes do processo de zincagem. In: CONFERÊNCIA SOBRE TECNOLOGIA DE EQUIPAMENTOS, COTEQ, 8., 2005, Salvador. Anais… (CD-ROM)