Chemical Passivation Services
Certified titanium chemical de-contamination and passivation workflows — nitric acid passivation for iron removal, biocompatible citric acid lines per ASTM F86, and deep HF-HNO3 acid pickling for heavy oxide stripping.
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Passivation Spectrum
Three distinct chemical decontamination and passivation paths — each engineered for specific titanium grades, surface conditions, and end-use environments.
Nitric Acid-Based Passivation
Utilizing calibrated high-concentration HNO₃ baths to selectively dissolve microscopic embedded free iron and tooling steel track debris, growing unified molecular passive film blocks.
- Calibrated 20–50 vol% HNO₃ baths at 20–60°C selectively dissolve embedded free iron particles without attacking titanium substrate
- Removes tooling steel transfer debris down to < 0.05 µg/cm² surface contamination levels
- Unified molecular TiO₂ passive film growth across entire surface — eliminating galvanic micro-cell corrosion sites
- Verified via potassium ferricyanide copper-spot testing protocols for zero free-iron certification
Biocompatible Citric Acid Lines
Designed under strict ASTM F86 guidelines leveraging advanced chelation software to pull foreign ions without attacking complex micro dimensional thread bounds on clinical implants.
- Chelation-driven citric acid formulation (10–20 wt%, pH 1.8–2.2) selectively binds free iron ions into soluble complexes — no substrate etching
- Zero attack on micro-dimensional thread forms (±0 µm material removal on threaded implant interfaces)
- 100% compliant with ASTM F86 for surgical implant passivation — validated ISO 10993-5 Grade 0 cytotoxicity
- Advanced bath chemistry monitoring with real-time chelation software ensures consistent ion removal efficiency across batch cycles
HF-HNO₃ Acid Pickling
Executing deep continuous chemical scaling to strip heavy heat oxides and ultra-brittle alpha cases off heavy forgings or weldments, recovering 100% bright metallic virgin skin profiles.
- Precision-blended HF-HNO₃ bath ratios (2–5% HF, 15–25% HNO₃) tailored per titanium grade and oxide thickness
- Complete alpha case removal from forged/machined surfaces — depth control within ±5 µm per application
- Strips heavy heat-treat oxides and weld discoloration revealing uniform bright metallic surface finish
- Multi-stage counter-current rinsing with ≥18 MΩ·cm DI water eliminates residual acid entrapment in crevices
Passivation Specifications Dashboard
Our chemical passivation processing purities — zero-trace free-iron verification, compliance accreditations, salt spray endurance, and native oxide layer continuity.
Surface Free-Iron Metric
Strict zero-trace parameters verified via potassium ferricyanide copper-spot testing protocols — no detectable free iron particles remaining on treated surfaces.
Compliance Accreditations
100% fully interlocked under ASTM F86, ASTM A967, and AMS 2700 Type 2/3 structural codes — full material traceability with batch-level certification documentation.
Cyclic Salt Spray Durability
Continuous anti-corrosion tracking exceeding 1,000+ hours zero-pitting boundaries per ASTM B117 standards — validated by accredited third-party corrosion laboratories.
Native Oxide Continuity
100% uniform amorphous TiO₂ film crystallization lacking micro crystal-boundary defects — verified via electrochemical impedance spectroscopy (EIS) across entire treated surface.
All specifications measured under ASTM B117 salt spray, ASTM F86 passivation standards, and AMS 2700 controlled conditions. Actual results depend on titanium grade, geometry complexity, and surface finish.
Hydrogen Embrittlement & Acid Control Engineering
Two critical failure mechanisms in titanium acid processing — hydrogen embrittlement from uncontrolled bath chemistry and residual acid entrapment in complex geometries. Our engineering solutions neutralize both risks.
Safe Volumetric Acid Ratio Controls
Uncontrolled HF-HNO₃ ratios (especially HF dominance) cause rapid hydrogen ion reduction at the titanium surface, leading to subsurface hydride formation, embrittlement fracture, and catastrophic in-service failure of critical load-bearing components.
Critical 3:1 HNO₃-to-HF Volume Ratio Barrier — Trapping Hydrogen Runaway Vectors
- Maintaining HNO₃-to-HF volume ratio strictly above 3:1 (typically 4:1 to 6:1) ensures HNO₃'s oxidizing power dominates, passivating the surface rather than reducing hydrogen
- Excess HNO₃ generates dense NOₓ and O₂ gas curtains at the reaction interface — physically blocking H⁺ ions from reaching the titanium substrate and diffusing into the lattice
- Real-time ratio monitoring via automated titration every 15 minutes ensures ratio never drops below the 3:1 safety threshold
- Preserves original alloy fracture toughness (KIC > 50 MPa√m for Grade 5 Ti-6Al-4V) with zero hydrogen pickup confirmed by vacuum hot extraction analysis to < 15 ppm H₂
Temperature-Locked Deionized Water Rinses
Exothermic acid pickling reactions can raise bath temperatures by 15–25°C, accelerating etch rates uncontrollably and causing over-etching of critical geometries, while residual acid trapped in micro-crevices leads to delayed corrosion and hydrogen infusion post-processing.
Automated Fluid Coolers (±2°C) + Multi-Stage 18 MΩ·cm DI Water Ultrasonic Agitation
- Closed-loop automated fluid coolers confine bath temperature within ±2°C of set point (15–25°C), preventing thermally-driven etch rate acceleration
- Multi-stage counter-current rinsing system with ≥18 MΩ·cm high-purity deionized water drives ultrasonic agitation to flush micro-crevices, blind holes, and threaded features completely
- Ultrasonic frequency sweep (40–80 kHz) ensures cavitation bubbles reach every surface feature — eliminating acid droplet entrapment in geometries with aspect ratios > 5:1
- Post-rinse conductivity verification ensures exit rinse water < 1 µS/cm — zero residual ionic species confirmed by ion chromatography analysis
Every bath cycle is logged and traceable. Hydrogen content data, bath chemistry logs, and rinse conductivity records accompany each batch — providing full material traceability for aerospace, medical, and semiconductor applications. Controlled chemistry delivers predictable performance.
Anti-Corrosion Passivation for Critical Environments —
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UHP semiconductor fluid system leads, deep-sea instrument developers, and orthopedic hardware buyers — upload your blueprints, testing standards, and corrosion resistance requirements for a rapid 24-hour commercial quote with full engineering review. Fully confidential under NDA.
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Founded in 2011 in Baoji's Titanium Valley, BOZE Metal is dedicated exclusively to titanium — from raw material to precision engineering. AS9100D, ISO 13485 & ISO 9001 certified with 500+ clients across Aerospace, Medical & Motorsport industries, we deliver end-to-end precision titanium CNC machining with full material traceability from source to component.
Boze CNC Ti is the dedicated titanium manufacturing center of Baoji Boze Metal Products Co., Ltd.