Crystallizer is the very important component of continuous casting machine. It is a compulsory water-cooling bottomless ingot mould called the "heart" of continuous casting equipment. It has good thermal conductivity, wear resistance, and adequate stiffness. In the past, copper is the material of most of the crystallizers. And copper can't meet these requirements. For this reason, many scholars have done a lot of work on crystallizers’ base materials. On the basis of summing up predecessors' experience, domestic scholars successfully plated nickel-tungsten-phosphorus alloy on copper and studied the influence of sodium tungstate content in the plating solution on the properties of coating.

 

This experiment is that adding sodium tungstate in basic solution to conduct electrodeposition to get nickel-tungsten- phosphorus alloy coating. The whole technological process: plating pretreatment - plating - washing with water - drying - postplating - performance testing. The specific methods of this experiment:

 

1. Levelling the surface: the base material of electroplating is zirconium copper used in crystallizer. Burnish the copper surface with sand paper to reduce roughness. Remove the defects of surface of the macroscopic such as scratches and rusty spot. Improve surface roughness to make it reach enough smoothness.

2. Skim: Using chemical method to remove surface oil. After using detergent to clean, use 5% of Na₂PO₄ weak base solution to heat to 80 ℃ or so. After putting the copper in it to mix, clean with water till no water is in the surface of whole substrate. 

3. The acid activation: Using chemical method to remove surface oxide. Use the solution of 1:2 volumes of HCl and  H₂SO₄, to leach the copper 3 to 5 minutes at room temperature. Activation is to counteract residual alkali of parts surface. What’s more, it is to remove the very thin oxide film produced by pretreatment. Metallographic organization is appeared to make the surface activation. After the treatment, we can obviously see that copper color becomes light.

4. Plating: After weak etching, immediately turn the parts cleaned with distilled water in the plating bath for plating.