Capability
Aluminum Conversion Coatings
Conversion coatings on aluminum are thin chemical reaction layers that form on the aluminum surface itself, transforming the natural aluminum oxide into a controlled, performance-engineered protective layer. The result is a coating that delivers corrosion resistance, paint adhesion, and (in the right chemistry) preserved electrical conductivity — without adding measurable thickness or changing the dimensional fit of the part.
CMC runs trivalent chromium process (TCP) conversion coatings — the modern, hexavalent-chromium-free chemistry that has replaced traditional hex-chrome chromate across most aerospace, defense, electronics, and automotive aluminum programs. The trivalent system delivers the same corrosion and adhesion performance as legacy hex chrome while meeting RoHS, REACH, and end-of-life vehicle directives.
Governing Standard
MIL-DTL-5541
Chemistry
Trivalent Cr
Class Options
1A & 3
Color
Clear or Yellow
Modern Hex-Chrome-Free Chemistry
Trivalent Chromium Process (TCP)
For decades, the standard aluminum conversion coating was a hexavalent chromium chromate process — highly effective, but increasingly restricted under modern environmental regulation due to the toxicity and carcinogenicity of hex-chrome chemistry. CMC runs the trivalent chromium process (TCP) — the industry-standard modern replacement.
TCP delivers equivalent or better corrosion and paint adhesion performance versus legacy hex-chrome chromate, while meeting RoHS, REACH, and end-of-life vehicle directives. The aerospace and defense industries have adopted TCP as the preferred conversion coating for aluminum across most current programs, qualified to the same MIL-DTL-5541 spec but as Type II trivalent rather than the older Type I hex-chrome chemistry.
Where Aluminum Conversion Coatings Fit
Common Applications
Aluminum conversion coatings are specified across aerospace, defense, automotive, and electronics programs whenever aluminum hardware needs corrosion protection, paint adhesion, or electrical bonding without compromising dimensional fit.
- Aerospace and defense hardware — structural brackets, panels, and frames where MIL-DTL-5541 compliance is the baseline expectation
- Automotive chassis — aluminum-bodied structural components and underbody hardware
- Electronic components and enclosures — where Class 3 preserves electrical conductivity for bonding and grounding
- Industrial structural supports and brackets — aluminum structural hardware for industrial equipment, racks, and frames
- Frames, connectors, and assembly hardware — general aluminum hardware that needs corrosion protection or a paint pre-treatment
- Pre-treatment for downstream finishing — conversion coatings are compatible with anodizing, welding, and adhesive bonding, so they can serve as either the final finish or the prep step for a layered finishing flow
Specifications & Standards
Standards We Can Meet
MIL-DTL-5541
Military specification for chemical conversion coatings on aluminum and aluminum alloys
ASTM B921
Standard specification for non-hexavalent chromium conversion coatings on aluminum (TCP)
AMS-C-5541
Aerospace material specification for chemical conversion coatings on aluminum
AMS-2474
Aerospace specification for chemical conversion coatings on aluminum alloys
IATF 16949
Automotive quality management process control across all facilities
RoHS, REACH, ELV, Hex-Chrome-Free
Trivalent chromium chemistry compliant with global directives
Specifying a conversion coating on an aluminum part?
Send us a drawing, a MIL or AMS specification, or a part description. We’ll confirm the right class (1A or 3), the right color, and the right downstream process compatibility before anything goes on a line.