Surface Treatment And Pickling Process Technology Of Titanium Rods

As an important form of titanium processed materials, the surface quality of titanium bars directly determines the service performance and service life of products. In the heat treatment process of titanium rods, good surface treatment ensure the Titanium products' performance.

 

 

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Titanium rods form loose, poorly bonded oxide scale when heated (reacting with air's oxygen, nitrogen, hydrogen), which impairs corrosion resistance, fatigue strength, and surface uniformity-posing risks for aerospace. Surface contaminants/oxide layers may trigger human rejection for medical implants. Surface defects in petrochemical pipelines can cause leakage. Moreover, surface treatment conditions impacts subsequent processes like coating and welding.

 

 

(I) Mechanical Treatment

Mechanical treatment is a basic treatment method that removes surface defects, oxide scale and contaminants of titanium rods through physical action.

Grinding and polishing are mainly used to remove micro-defects such as scratches and cracks on the surface of titanium rods and improve surface finish.

Sandblasting uses high-speed jet abrasive (such as alumina, quartz sand) to impact the surface of titanium rods.

Tumbling treatment is suitable for surface treatment of batch titanium rods.

 

(II) Chemical Treatment

Use chemical reagents to react with titanium rod surfaces for cleaning, modification, or protective film formation. Common methods include pickling (the most widely used), chemical polishing, and chemical conversion film treatment, with pickling dissolving surface oxides, impurities, and oil stains in order to restore a clean metal appearance and enhance corrosion resistance through a thin oxide film.

 

(III) Electrochemical Treatment

Use the anodic dissolution of titanium rods in electrolyte to remove surface micro-defects and to obtain better surface finish and flatness.

 

(IV) Vapor Deposition Treatment

Deposits a functional thin film on the surface of titanium rods with gas-phase chemical reactions or physical processes, including physical vapor deposition (PVD), chemical vapor deposition (CVD), etc.

 

 

(I) Pickling Solution Formula

Basis: Titanium rod (pure titanium, titanium alloy), surface oxide scale thickness, according to treatment requirements

Common pickling systems: Hydrofluoric acid-nitric acid (widely used), hydrofluoric acid-sulfuric acid

Hydrofluoric acid (HF) : Dissolves titanium and its oxides; affects pickling speed

HF concentration: 1%-5%

(high = excessive corrosion/pitting; low = low efficiency/unremoved scale)

Nitric acid (HNO₃) : Oxidizes to inhibit excessive HF corrosion; aids uniform passivation film formation

HNO₃ concentration: 10%-20%

Optional additives: Corrosion inhibitors (reduces matrix corrosion), surfactants (enhances oil emulsification/cleanliness)

 

(II) Control of Key Process Parameters

Pickling temperature: 20-50℃ (avoid high/low extremes)

Pickling time: 5-30 minutes (adjust by oxide scale thickness; confirm via sampling)

Acid solution circulation speed: Ensure good circulation (for full contact and reaction product removal)

 

(III) Pickling Process Flow

The typical process of titanium rod pickling includes: pretreatment → pickling → water washing → passivation → drying.

 

 

 

 

• Composite treatment : Combine multiple technologies ( "sandblasting + pickling + anodizing", "electropolishing + plasma spraying") to achieve enhanced effects, such as improved corrosion resistance and bone bonding ability, suitable for medical devices.
• Green process : Optimize traditional pickling defects with low-toxicity/low-emission technologies, for example citric acid-hydrofluoric acid system, acid-free methods like laser (no pollution, high precision) and ultrasonic cleaning.
• Intelligent process: Choose online monitoring (real-time detection of acid concentration, etc.) and PLC/robot technologies to realize precise parameter adjustment, automatic operation, and improved treatment consistency.