بررسي عوامل موثر بر سينتيك پوشش دهي فولاد ساده به روش گالوانيزه گرم روي

An Experimental Study of the Parameters Affecting the Kinetics of Hot-dip Galvanizing of Plain Carbon Steel

در اين پژوهش تاثير عوامل مختلفي اعم از دمي حمام مذاب، دماي پيشگرم و ماسه پاشي بر سينتيك پوشش دهي فولاد ساده به روش گالوانيزه روي مورد بررسي قرار گرفته است. نتايج نشان داد افزايش دماي مذاب روي بر k بي تاثير ولي n را افزايش مي دهد، افزايش دماي پيشگرم نيز بر سينتيك رشد لايه پوشش تثير دو گانه اي داشت؛ يعني با افزايش دماي پيشگرم، سرعت رشد لايه با افزايش k افزايش و با كاهش n كاهش يافت. ماسه پاشي نيز با افزايش هر دو مقدار k و n،سينتيك رشد لايه ها را بطور چشمگيري افزايش داد.

The hot immersion galvanizing process is known as one of the techniques frequently used for protecting steels against corrosion. Hot dip galvanizing is a process in which an adherent, protective coating of iron-zinc alloys is developed on the surface of steel products by immersing them in a bath of molten zinc. Several kinetics parameters such as bath temperature, surface roughness and the chemistry of both the bath and the substrate steel affect structure and properties of coating. The purpose of this work was to identify the influence of bath temperature, surface roughness and drying temperature before immersion in the molten bath on the morphology, coating thickness and kinetics of the interfacial layer growth. It was found that 1) the coating thickness reaches maximum at 480°C and minimum at 450°C.The increase of bath temperature is ineffective on K value but it increase n value. When the temperature is 510°C thickness is reduced because of the absence of the zeta phase and erosion of the coating. 2) The grain sizes of zeta phase become bigger with the increase of drying temperature. At 25°C and 150°C, the cracks are deeper than70°C.The increase of drying temperature had different influence on the layer growth kinetic as K value is increased but n value is reduced with the increase of drying temperature. 3) Sand blasting made the coating grow faster and it is resulted the appearance of zeta layer again when the immersion time is up to 7 min.