Electropolishing is an electrochemical process by which surface material is removed byanodic dissolution.
Electropolishing removes surface material, beginning with the high points within themicroscopic surface texture. By removing the sepoints, the electropolishing process will improve the surface finish of a metal such as stainless steel, nickel, aluminum and hastelloy, leaving a smoother and more reflectivesurface.
The benefit of electropolishing is that it delivers a smoother, more reflective surface that reduces product adhesion and improves surface clean ability. Perhaps more importantly, electropolishing preferentially dissolves free iron, inclusions, and embedded particles from the surface of the work-piece. This process improves the near surface chemistry of the material, and promotes the formation of an improved corrosion resistant surface layer. Process under the standard ASTM B 912-02.

Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized.
The anodic oxide structure originates from the aluminum substrate and is composed entirely of aluminum oxide. This aluminum oxide is not applied to the surface like paint or plating, but is fully integrated with the underlying aluminum substrate, so it cannot chip or peel. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing.
Anodizing is accomplished by immersing the aluminum into an acid electrolyte bath and passing an electric current through the medium related to ASTM B580 - 79. A cathode is mounted to the inside of the anodizing tank; the aluminum acts as an anode, so that oxygen ions are released from the electrolyte to combine with the aluminum atoms at the surface of the part being anodized.
Anodizing is, therefore, a matter of highly controlled oxidation—the enhancement of a naturally occurring phenomenon.
Anodized finishes have made aluminum one of the most respected and widely used materials today in the production of thousands of consumer, commercial and industrial products.
Anodized Aluminum:
• Protects satellites from the harsh environment of space.
• Used in one of the world's tallest buildings --- the Sears Tower in Chicago, Illinois.
• Provides attractive, minimum-maintenance, highly durable exteriors, roofs, curtain walls,
ceilings, floors, escalators, lobbies and staircases in skyscrapers and commercial
buildings throughout the world.
• Revolutionized the construction of computer hardware, exhibit displays for trade shows,scientific instruments, and a constantly expanding array of home appliances, consumer products, and building materials.
• Considered environmentally safe, producing few, if any, harmful effects on land, air, orwater.

Nickel plating is the process of electrolytic ally depositing a layer of nickel. Parts processed with a bright nickel plating layer maintain their surface appearance and brightness over time, is commonly used as a base plating layer as it provides excellent adhesion between layers and can have a leveling effect on pits or other defects in the base material, is extremely resistant o atmospheric corrosion, making tan excellent choice as a final layer, Is also a magnetic material, making it an attractive option when magnetic properties are required, can provide improved wear resistance to soft metals such as copper, resulting in longer service life, also provides a superior barrier layer between metals that can experience self diffusion into each other such as copper and tin. Process under the Standard ASTM B689-97

The tin-plating process is used extensively to protect both ferrous and non ferrous surfaces. Tin is a useful metal for the food processing industry since it is non-toxic, ductile and corrosion resistant. The excellent ductility of tin allows a tin coated base metal sheet to be formed into a variety of shapes without damage to the surface tin layer. It provides sacrificial protection for copper, nickel and other non-ferrous metals.
Tin is also widely used in the electronics industry because of its ability to protect the base metal from oxidation thus preserving its solder ability. Process under the Standard ASTMB545.

Zinc plating is used on small parts such as fasteners, crank handles, springs and other hardware items rather than sheet metal that will be exposed in interior or mildly corrosive conditions. The zinc is applied as an expendable electrode in a cyanide, alkaline non-cyanide, oracid chlorides alt solution.
The normal zinc-plated coating is dull gray in color with a mattefinish, although whiter, more lustrous coatings can be produced, depending on the processor agents added to the plating bathor through post-treatments. The coating is thin, ranging up to 1 mil (25 μm), restricting zinc-plated parts to very mild (indoor) exposures.
ASTM Specification B 633 lists four classes of zinc plating, coating thickness in microns (μm): Fe/Zn 5, Fe/Zn 8, Fe/Zn 12 and Fe/Zn 25.
Trivalent Chromium Passivation finish:
Clear Zinc or Blue Clear, Yellow, Green Olive and Black.

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