Passivation
Precision Cerakote ceramic coatings for aerospace, defense, and industrial components.
How Passivation Works at ColoradoKote
Passivation removes free iron and contaminants from stainless steel surfaces using controlled acid bath chemistry per ASTM A967 and AMS 2700. The process brings chromium to the surface, restoring the passive oxide layer that gives stainless steel its corrosion resistance, with zero dimensional change.
What Sets Us Apart
ColoradoKote controls acid concentration, temperature, and immersion time to match each stainless steel alloy’s requirements. We process 300-series, 400-series, and precipitation-hardened stainless steels with chemistry tailored to each grade. When combined with chemical conversion on aluminum components and Cerakote topcoat, the full protection stack covers mixed-material assemblies in a single facility.
Aerospace Standards
Every passivation batch is documented with acid type, concentration, temperature, immersion duration, and verification results per ASTM A967 and AMS 2700 under AS9100 controls. Post-passivation testing confirms free iron removal and oxide layer integrity. Complete traceability from bare stainless steel to verified passive surface ships with your Certificate of Conformance.
What Passivation Delivers for Your Stainless Steel Parts
Passivation restores the corrosion resistance that machining, welding, and handling compromise. Here is what it means for your parts.
Chromium Oxide Layer Restored
Machining, welding, and grinding embed free iron particles in stainless steel surfaces, compromising the natural passive layer. Acid bath passivation dissolves free iron and brings chromium to the surface, restoring the protective chromium oxide film that prevents corrosion in service.
Zero Dimensional Change
Passivation removes contaminants without adding material or altering part dimensions. Precision-machined stainless steel components maintain their tolerances exactly as delivered from your machine shop, making passivation ideal for tight-tolerance aerospace and medical components.
Combined Protection Stack
Passivation pairs with Cerakote ceramic topcoat for stainless steel components requiring maximum protection. The restored chromium oxide base layer bonds with Cerakote at the molecular level, combining the inherent corrosion resistance of properly passivated stainless steel with 3,000+ hours of ceramic barrier protection.
Technical Specifications for Passivation Services
| Specification | Value | Test Method |
|---|---|---|
| Process Standard | ASTM A967 / AMS 2700 | Process Control |
| Applicable Materials | 300 series, 400 series, precipitation-hardened stainless steels | Material Verification |
| Bath Chemistry | Citric acid or nitric acid (per customer spec) | Solution Monitoring |
| Dimensional Change | None (chemical process only) | Pre/Post CMM |
| Verification | Copper sulfate test (ASTM A967) or water immersion test | ASTM A967 |
| Surface Result | Chromium-enriched oxide layer | XPS/AES Analysis |
| Compatible With | Cerakote topcoat, bare exposure, assembly | Application-Specific |
Certifications: AS9100 | ISO 9001 | ITAR
Parts received, material verified, and tracking begins
Parts arrive and are logged into our AS9100 tracking system. Material grade is confirmed (300 series, 400 series, PH grades) against your documentation. Incoming condition is photographed and documented. Lot numbers are assigned and chain of custody begins.
Surface contaminants removed before acid bath
Parts are degreased and cleaned to remove oils, machining fluids, and handling residues. Ultrasonic cleaning addresses complex geometries and internal features. Pre-cleaning ensures the passivation acid contacts bare stainless steel rather than reacting with surface contaminants.
Surface is cleaned and made ready for coating
Degreasing, cleaning, and light abrasion remove contaminants and create the ideal surface for adhesion. This step determines coating quality.
Controlled acid bath removes free iron and enriches chromium
Parts are immersed in citric or nitric acid solution per ASTM A967 or AMS 2700 specification. Bath temperature, concentration, and immersion time are controlled and documented per the applicable standard. The acid dissolves free iron particles embedded during machining and fabrication, allowing chromium to migrate to the surface and form a dense, protective oxide layer.
Ceramic coating is applied in controlled layers
We apply the coating using precision equipment, monitoring thickness and coverage. Each layer cures before the next is applied, building a durable finish.
Rinsed, dried, and verified for passivation quality
After passivation, parts are thoroughly rinsed with deionized water to remove all acid residue. Verification testing (copper sulfate per ASTM A967 or water immersion test) confirms successful passivation. Parts that do not pass verification are re-processed or flagged for engineering review.
Coating hardens and bonds to the substrate
The coating cures under controlled temperature and humidity. We don't rush this phase. Full cure strength takes time, and we give it that time.
Final inspection and documentation
Visual inspection confirms surface condition. Dimensional verification confirms no material loss. Certificate of Conformance documents process parameters, verification test results, and material traceability. Parts are packaged for shipment or transferred to Cerakote application if topcoat is specified.
Every part is measured and tested before shipment
We measure coating thickness, check for defects, and verify specifications. Documentation is prepared for your records. Only parts that pass leave our facility.
Frequently Asked Questions
Find answers about our coating processes and technical capabilities
Every Cerakote job at ColoradoKote is tracked under our AS9100:2015 quality management system with full material batch numbers, application parameters, cure profiles, and inspection data. Parts ship with a Certificate of Conformance documenting coating thickness (0.5-2 mils), adhesion, color consistency (Delta E 1.5), and all process variables. This level of documentation satisfies aerospace OEM and Tier 1 supplier quality requirements, including those we maintain for multiple manufacturers.
In many aerospace applications, yes. Cerakote delivers 3,000 hours of salt spray resistance (ASTM B117) compared to 336-1,000 hours for anodizing, and it eliminates the 20-60% fatigue debit that anodizing causes on aluminum substrates. It also works on titanium, Inconel, and composites, not just aluminum. We recommend discussing your specific specification requirements during quoting, as some programs require formal qualification testing for coating substitution.
Cabin interior components typically use H-Series Cerakote, which meets aerospace flammability requirements per third-party testing against Cerakote lab reports. The coating adds only 0.5-2 mils of thickness, preserving tolerances on latches, brackets, and trim components. Color consistency at Delta E 1.5 ensures visual uniformity across large cabin interior programs where hundreds or thousands of parts must match precisely.
At 0.5-2 mils thickness, Cerakote preserves interference fits and thread engagement that powder coating at 4-6 mils cannot maintain. We mask threaded holes, bearing surfaces, and critical datum features per documented masking plans reviewed against your engineering drawings. Over 20,000 parts coated with zero quality issues demonstrates the process control needed for precision aerospace hardware.
Yes. We run the complete preparation-to-coating sequence in-house: ultrasonic cleaning removes machining fluids and contaminants from blind holes and internal passages, chemical conversion coating (chromate or non-chromate) provides the adhesion-promoting base layer, and Cerakote ceramic coating delivers the final corrosion and wear barrier. Running this full stack under one AS9100 quality system eliminates handoff risk between multiple vendors and compresses your lead time.
Start Your Passivation Project
Request a passivation quote. We respond within 24 hours with process recommendations and pricing.
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