Metals & Chemicals

The extensive use of zinc, both as a sacrificial coating on steel and also as a stand-alone material, require a high level of corrosion resistance in order to increase the product life cycle and to avoid ecological pollution by metal ions. Zinc coatings and castings on steel can be anodized so as to produce a tough and stable coating. The corrosion resistance is said to be superb. Being used by the military immersed on the subs for high corrosion problem areas such as mooring cleats with good results. A special zinc anodizing handling is available for zinc castings. This coating is entirely different than that for aluminum alloys. Anodizing zinc is a practical coating providing maximum corrosion resistance in both atmospheric and marine environments. As the process uniformly coats deep recess and threaded areas, anodized zinc alloy castings could serve as an economical alternative when replacing traditional bronze, brass and stainless steel components. Steel items could be fabricat...

In the chromate conversion process, part of the metal surface is converted to a superficial layer containing a complex combination of chromium compounds. The chromate film will be soft when freshly formed, but once it gets dried and aged, the layer becomes more rough resistant. Chromate conversion coatings provide excellent corrosion resistance. Paint, polish, and organic finishes will bond exceedingly well to chromate conversion coatings. Additionally, the chromate coatings will prevent loss of plain adhesion due to under film corrosion. The most common use for chromating is to impart corrosion resistance to zinc aluminium parts and zinc plated steel. These films will vary in color depending upon the chemicals being used and the bottom metal being coated. Colors vary from clear, to light shining, to gold. Greater corrosion protection is given with formulations that gives a golden color, since these coatings tends to be thicker. A multicolored appearance will be obtained when the b...