Method for galvanizing steel member of support for solar photovoltaic or photothermal system

Abstract

Disclosed is a method for galvanizing a steel member of a support for a solar photovoltaic or photothermal system, which relates to metal surface treatment. The method includes: subjecting the steel member to phosphorus-free degreasing and then pickling; dipping the steel member in a flux solution; drying the steel member; and subjecting the steel member to hot-dip galvanization, cooling and passivation to produce galvanized steel member.

What is claimed is: 
     
         1 . A method for galvanizing a steel member of a support for a solar photovoltaic or photothermal system, comprising:
 subjecting the steel member of the solar photovoltaic or photothermal support system to phosphorus-free degreasing and then pickling;   dipping the steel member in a flux solution;   drying the steel member; and   subjecting the steel member to hot-dip galvanization, cooling and passivation to produce galvanized steel member.   
     
     
         2 . The method of  claim 1 , wherein a degreasing agent used in the phosphorus-free degreasing is an aqueous solution of an OP emulsifier; and the OP emulsifier in the degreasing agent is 2-3% by weight. 
     
     
         3 . The method of  claim 1 , wherein the phosphorus-free degreasing is performed at 25-45° C. for 25-30 min. 
     
     
         4 . The method of  claim 2 , wherein the phosphorus-free degreasing is performed at 25-45° C. for 25-30 min. 
     
     
         5 . The method of  claim 1 , wherein an acid used in the pickling is a 15-25% hydrochloric acid solution; and the pickling is performed at room temperature. 
     
     
         6 . The method of  claim 1 , further comprising:
 after the pickling, rinsing the steel member with water.   
     
     
         7 . The method of  claim 5 , further comprising:
 after the pickling, rinsing the steel member with water.   
     
     
         8 . The method of  claim 1 , wherein the flux solution is an aqueous solution of a mixture of zinc chloride and ammonium chloride; a total percent by weight of zinc chloride and ammonium chloride in the aqueous solution is 20-30%; and a weight ratio of ammonium chloride to zinc chloride is 0.8-1.6:1. 
     
     
         9 . The method of  claim 1 , wherein a temperature of the flux solution is 55-65° C. 
     
     
         10 . The method of  claim 8 , wherein a temperature of the flux solution is 55-65° C. 
     
     
         11 . The method of  claim 1 , wherein a hot-dip galvanization temperature is 436-440° C. 
     
     
         12 . The method of  claim 1 , wherein the cooling is performed with water; and the steel member is cooled to 45-47° C. through water cooling. 
     
     
         13 . The method of  claim 1 , wherein a passivation solution used in the passivation is a mixed solution of aluminate and a water-soluble acrylic resin; and a weight ratio of the aluminate to the water-soluble acrylic resin in the mixed solution is 1:3.