ChemfilmChromate Conversion Coatings
Chemfilm Aluminum Coating
Using Tri-valent Chrome
Chemfilm – hex chrome free and meets ELV, RoHS and WEEE initiatives.
Chemfilm, or chromate, is a conversion coating of aluminum using the base material to create a very thin film on the surface of the part. The coating thickness is near unmeasurable and will not create any dimensional change of the work piece.
Chemfilm Class 3 alone will give moderate corrosion resistance to parts while maintaining a low electrical resistance. Class 1A will give a slightly thicker coating for increased corrosion protection but with a higher electrical resistance.
Chemfilm can be used as a stand alone coating, under paint or in combination with anodizing to create electrical contact areas.
Offering Selection
Process | Clear Anodizing | Black Anodizing | Chemfilm | SS Passivation |
|---|---|---|---|---|
Material used on | Aluminum | Aluminum | Aluminum | Stainless Steel |
Coating thickness | 0.2 – 0.8 mil | 0.6 – 1.2 mil | 0 – not measurable | 0 – no coating buildup |
Dimensional increase | ~50% of coating thickness | ~50% of coating thickness | None | None |
Electrical conductivity | None, insulator | None, insulator | Type 3 – very good; Type 1A – good | No change from base material |
Specifications | MIL-A-8625F type II class 1 | MIL-A-8625F type II class 2 (black) | MIL-DTL-5541 type II, class 1A and 3 | AMS2700 method 2, ASTM-A967 citric 2 |
Appearance/color | Gloss silver to matte silver | Medium gloss black to matte black | Slight yellow to blue tint to base material. Some light streaking possible | No change to base material – SS appearance |
Corrosion resistance | Very good – 336 hour salt spray | Very good – 336 hour salt spray | Good – 100 hour salt spray | Excellent – no salt spray corrosion |
ELV/WEE compliant | Yes | Yes | Yes | Yes |
Cost of process | $$ | $$$ | $ | $ |
Max part size at WFL | 30″ x 30″ x 48″ | 30″ x 30″ x 48″ | 30″ x 40″ x 108″ | < 5" - bulk barrel |
