You may find that zinc plating is not a good anti-rust solution for iron sand casting parts.
Because cast iron has a high carbon content, the structure is loose and porous. There will be sand holes and shrinkage cavities, and the surface also contains a large amount of free graphite carbides, thereby lowering the precipitation potential during electroplating. In addition, the surface of the cast iron is rough and uneven, which reduces the overpotential of hydrogen, and hydrogen is easily precipitated, which increases the difficulty of electroplating of cast iron parts.
So painting, powder coating or e-coating will be a good choice for iron sand casting parts.
Or we can use steel investment casting instead of iron sand casting to keep the zinc plating surface.
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