抄録
By photometric method of analysis, the author determined the chemical composition of the coating with reference to its contained chloride by adding 3N-HNO3 as oxidizing agent for Fe.. to the stripping solution of 3N-H2SO4, changing Cl′ in the solution into hydrosol of AgCl with 0.1% AgNO3.
The results obtained were as follows:
(1) Cl-content in the coating produced by Dry Golvanizing Method of washing with hot flux solution such as 5N-NH4Cl or 5N-ZnCl2·NH4Cl was about 0.01% by weight and with 5N-ZnCl2 was about 0.03%.
Conditions of this experiment were as follows:
Material used was 0.6C steel wire, composition of bath electrolytic zinc, temperature of Zinc bath 450°C, and dipping time 1-2min; hand dipping process being used.
(2) When produced by washing with cold flux solution such as 5N-HCl, 5N-NH4Cl or 5N-ZnCl2, Cl-content was 0.08-0.10%.
Conditions of this experiment were as follows:
Material used was black heart malleable iron, and other conditions were the same as the above.
(3) Cl-content in the coating produced by Wet Galvanizing Method, of using machine and washing with Pb-Zn bath was also 0.01-0.10%. The longer the dipping time in Pb-bath was the less was the Cl-content in the coating.
Conditions of this experiment were as follows:
Specimens used in these experiments were the product of certain factories. Material used was 0.1C sheet, composition of Zinc bath, spelter with 0.1-0.2% Sn and 0.1% Sb, temperature of Zinc bath 450°C±10°C, temperature of Pb-bath 480°C, and dipping time in Pb-bath 7-18sec.
