Protecting Aluminum Alloys from Corrosion

Vanconol® Aluminum Alloy Corrosion Inhibitor Technical Guide

Tianjin Hi-Perferal Advanced Materials Co., Ltd.  |  Metal Corrosion Inhibition Division

Tianjin Hi-Perferal Advanced Materials Co., Ltd.

Understanding the “Nemesis” of Aluminum Alloys: Corrosion

Aluminum alloys are among the most widely used lightweight materials in the world today—from new energy vehicle battery packs to aerospace structural components, from building curtain walls to consumer electronics housings, aluminum is everywhere. However, aluminum alloys are not invincible. Their “nemesis” is the familiar yet often underestimated phenomenon of corrosion.

In every stage of metalworking fluid application, alkaline cleaning, acid pickling processes, and even routine storage, moisture, oxygen, acidic/alkaline media, and airborne chloride ions can silently penetrate the natural oxide protective film (Al2O3) on aluminum alloy surfaces, triggering a host of troublesome issues: loss of surface luster and dull gray discoloration (tarnishing), uniform gray or even black discoloration (blackening), white corrosion products on the surface (white rust), as well as more destructive localized perforation (pitting) and intergranular corrosion.

A more pressing challenge comes from the new energy vehicle era. Power battery liquid cooling plates use 3003 aluminum alloy and are immersed long-term in ethylene glycol-containing coolants; integrated die-cast aluminum alloy components face high-temperature steam attack during solution heat treatment and quenching processes; and the microchannel structures of aluminum heat exchangers are highly susceptible to blockage or even perforation leakage once corrosion products deposit.

In response to these challenges, corrosion inhibitors—often hailed as the “most convenient, most economical, and most effective” metal protection approach—are playing an increasingly critical role in the aluminum alloy field.

I. How Do Corrosion Inhibitors Protect Aluminum Alloys?

1.1 Working Principles of Corrosion Inhibitors

Corrosion inhibitors are chemical substances that, when present in a corrosive medium at appropriate concentrations, can significantly reduce the corrosion rate of metals upon adsorption onto the metal surface. The core principles can be summarized in three key points:

Physical or chemical adsorption: The polar groups (-OH, -COOH, -NH2, etc.) in inhibitor molecules adsorb directionally onto the active sites of the oxide film on aluminum alloy surfaces, effectively providing the metal with a “molecular protective garment.”

Film formation protection: Inhibitor molecules form a dense protective film between the metal surface and the corrosive medium, physically blocking direct contact between water, oxygen, and corrosive ions with the metal substrate.

Electrochemical suppression: Inhibitor molecules raise the overpotential of anodic or cathodic reactions, suppressing electrochemical corrosion and thereby reducing the overall corrosion rate.

1.2 Vanconol® Core Corrosion Inhibition Technologies

The Vanconol® aluminum alloy corrosion inhibitor series encompasses three core technology platforms, each tailored to deliver precise protection for different application scenarios:

First, Schiff base technology (Vanconol® SA-90): Schiff bases are a class of organic compounds containing imine (C=N) unsaturated bonds. Their molecular structure incorporates heteroatoms such as nitrogen (N) and oxygen (O) along with C=N unsaturated bonds, enabling chemical adsorption to form a dense, stable protective film on aluminum alloy surfaces. In 5% acid media, SA-90 consistently achieves corrosion inhibition efficiency exceeding 90%, while also offering thermal stability and a broad operating temperature range (20°C to 60°C). More importantly, its formulation is completely free of phosphorus and APEO (alkylphenol ethoxylates), making it an ideal replacement for traditional toxic corrosion inhibitors.

Second, phosphate ester technology (Vanconol® ALI-910 / ALI-1214): Phosphate ester corrosion inhibitors represent the mainstream technology in the current aluminum alloy working fluid market. Their molecular structure combines the strong adsorption and chelating capability of phosphate groups (-PO3H2) with the excellent water solubility and penetrative properties of polyether chains. The phosphate groups rapidly chelate with the aluminum alloy surface, forming a hydrophobic, dense monomolecular protective film; the polyether long chains impart outstanding penetrability and coverage over complex workpiece geometries. ALI-910 is based on C9-10 polyether, while ALI-1214 is derived from natural fatty alcohol polyethers. Both products deliver exceptional resistance to strong alkalis (NaOH ≤ 200 g/L), high temperatures (≤ 90°C), and hard water, maintaining stability across a broad pH range of 6–12.

Third, amino acid/carboxylic acid synergistic technology (Vanconol® ALI-1120): This represents Vanconol®’s forward-looking positioning in environmentally friendly aluminum alloy corrosion inhibition. ALI-1120 is formulated from carefully synergized amino acid and carboxylic acid compounds, completely free of restricted substances such as phosphorus, chromium, boron, and nitrites. The selected components exhibit a pronounced synergistic corrosion inhibition effect—organic molecules undergo directional adsorption onto active sites of the oxide film through functional groups, forming a hydrophobic barrier film, while specific components react with magnesium ions to form a dense passivation layer that reinforces substrate protection. This dual “adsorption + passivation” mechanism delivers superior overall corrosion inhibition performance compared to single-component systems, providing excellent protection for aluminum and aluminum alloys across the 1xxx, 2xxx, 5xxx, and 6xxx series.

II. Vanconol® Aluminum Alloy Corrosion Inhibitor Product Line

The Vanconol® aluminum alloy corrosion inhibitor series now forms a complete product matrix covering four major application scenarios: acid pickling, working fluids, cleaning agents, and process-stage rust prevention. The following table presents a comparison of key parameters for each product:

Product	Core Composition	Recommended Dosage	Primary Applications
Vanconol SA-90	Schiff base derivatives	0.1%-0.3%	Acid pickling and chemical polishing of aluminum alloys
Vanconol ALI-910	C9-10 polyether phosphate ester	1%-5%	Aluminum alloy machining fluids, cleaning agents
Vanconol ALI-1120	Amino acid and carboxylic acid blend	2%-10%	Alkaline cleaning agents, in-process rust prevention
Vanconol ALI-1214	Natural fatty alcohol polyether phosphate ester	0.2%-3%	Forming lubrication, rust prevention chemicals

Detailed technical specifications for each product are as follows:

2.1 Vanconol SA-90: Corrosion Inhibitor Specifically for Aluminum Alloy Acid Pickling

Vanconol SA-90 is specifically designed for corrosion protection of aluminum alloy materials in acidic environments. Its key selling point is a stable corrosion inhibition efficiency exceeding 90% in common pickling solutions such as 5% sulfuric acid, hydrochloric acid, and nitric acid, effectively suppressing over-pickling, pitting corrosion, and hydrogen embrittlement.

Technical Specifications:Appearance: amber to light yellow transparent liquid; pH (as supplied) 6.0-8.0; Density (20°C) 1.05±0.05 g/cm³; Active content ≥30%; Readily soluble in water and acidic media.

Application Scenarios:Acid pickling prior to spraying/electrophoresis of aluminum alloy profiles (architectural aluminum profiles, door and window frames, etc.); surface cleaning of automotive aluminum alloy wheels, radiators, and other components; acid pickling of aluminum alloy casings and heat sink modules for electronic products; maintenance and cleaning of aluminum alloy components in aircraft.

Usage Instructions:Recommended dosage: 0.1%-0.3% (i.e., 1-3 kg of this product per 1000 liters of pickling solution). It is recommended to add this product to the pickling tank first during bath make-up, circulate for uniformity, and then add the acid. Alternatively, it can be continuously metered into the working pickling solution.

2.2 Vanconol ALI-910: C9-10 Polyether Phosphate Ester Corrosion Inhibitor

ALI-910 is the flagship product in the Vanconol aluminum alloy corrosion inhibitor series, specifically designed for high-performance aluminum alloy machining fluids and widely recognized within the industry.

Technical Specifications:Appearance: colorless to light yellow transparent viscous liquid; Solid content ≥95%; pH (2% aqueous solution) ≤3.0; Ionic type: anionic; Acid value: 280-320 mgKOH/g; Phosphorus content: 6%-8%; Resistant to strong alkalis (NaOH ≤200 g/L), high temperatures, and hard water; not prone to hydrolysis.

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Application Areas:Aluminum alloy machining fluids (corrosion inhibitors/rust preventives in cutting fluids, grinding fluids, and lapping fluids); metal cleaners and pretreatment (corrosion inhibitor components in degreasers and cleaning solutions); forming processes and specialty lubrication (corrosion inhibitors/extreme pressure additives in cold rolling emulsions, stamping fluids, wire drawing oils, and lubricant formulations).

Recommended Dosage:A dosage of 1%-5% is recommended for aluminum alloy machining fluid formulations. The optimal dosage should be determined through testing based on water hardness, machining process severity, and rust protection requirements.

Reference Formulation Example:ALI-910 phosphate ester (3%-5%) + triethanolamine (2%-4%, for pH adjustment and synergistic corrosion inhibition) + borate ester corrosion inhibitor (3%-5%, to enhance rust protection) + coupling agent (e.g., isopropanol, 2%) + deionized water (balance). For optimal corrosion inhibition performance, use in a weakly alkaline environment (pH 8.0-9.5). Long-term operating temperatures should not exceed 80°C.

2.3 Vanconol ALI-1120: Amino Acid/Carboxylic Acid Compound Corrosion Inhibitor

ALI-1120 is a next-generation environmentally friendly aluminum alloy corrosion inhibitor developed by Vanconol in response to global trends toward green chemical products. Its key feature is a phosphorus-free, chromium-free, and boron-free environmentally friendly formulation, designed to meet the most stringent environmental regulations.

Technical Specifications:Appearance: colorless to light yellow transparent liquid; Active content: 40+/-2%; Density (20°C): 1.10-1.15 g/cm³; pH (1% aqueous solution): 7.0-10.5; Fully water-soluble.

Applications and Recommended Dosage:Metalworking fluids (cutting and grinding of aluminum and aluminum alloys), recommended dosage 3%-8%; alkaline cleaners (degreasing and cleaning of aluminum component surfaces), recommended dosage 2%-5%; inter-process rust protection (can be used as an inter-process rust preventive solution), recommended concentration 5%-10% aqueous solution.

Usage Instructions:It is recommended to add this product to water first when preparing the working solution, stir thoroughly, and then add other components. Deionized water is recommended for preparing the solution to achieve optimal results. The optimal pH range is 8.5-10.0; however, it remains effective over a broad pH range of approximately 7-11.

2.4 Vanconol ALI-1214: Natural Fatty Alcohol Polyether Phosphate Ester Corrosion Inhibitor

ALI-1214 is manufactured through the phosphation of natural fatty alcohol polyether, combining the excellent performance of ALI-910 with enhanced environmental compatibility and multifunctional synergistic characteristics.

Technical Specifications:Appearance: colorless to slightly yellow paste; Solid content: >=95%; pH (2% aqueous solution): <=3.5; Acid value: 120-140 mgKOH/g; Phosphorus content: 3%-5%; Easily soluble in water, ethanol, and ethylene glycol; Ionic type: anionic, compatible with nonionic and amphoteric surfactants.

Key Features:Extremely broad environmental adaptability—resistant to acids, alkalis (pH 6-12), and hard water; maintains activity at temperatures up to <=90°C and in high inorganic salt environments. Multifunctional synergy—provides lubricating, emulsifying, dispersing, and antistatic functions, which can reduce the dosage of other additives in machining fluids and lower overall formulation costs.

Recommended Dosage:A recommended dosage of 0.2%-3% is suggested for aluminum alloy machining fluid formulations. Reference formulation: ALI-1214 phosphate ester (3%) + triethanolamine borate (1%) + lubricant (3%) + deionized water (balance). Optimal pH range: 6.0-9.5. Long-term operating temperature <=80°C.

3. Core Competitive Advantages of Vanconol Aluminum Alloy Corrosion Inhibitors

In the increasingly competitive market for aluminum alloy corrosion inhibitors, what sets the Vanconol series apart? The following analysis from six key dimensions provides the answer:

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Dimension	Advantages of Vanconol ALI Series	Industry Context & Needs
Environmental Compliance	Phosphorus-free, chromium-free, APEO-free; complies with RoHS/REACH	EU CBAM is driving carbon reduction across the aluminum lifecycle; phosphorus-containing corrosion inhibitors face phase-out due to environmental regulations
Broad pH Adaptability	ALI-910 withstands strong alkalis (NaOH<=200g/L); ALI-1120 effective at pH 7-11	New national standard for new energy vehicle coolants requires pH 7.0-10.0; alkaline cleaning processes are gaining widespread adoption
Temperature tolerance	<=90°C stable operation (ALI-910/ALI-1214)	The widespread adoption of high-temperature processing techniques such as integrated die-casting imposes higher thermal stability requirements on corrosion inhibitors.
Hard water compatibility	Resistant to hard water, not prone to saponification (ALI-910/ALI-1214)	Water quality varies significantly across metalworking sites; hard water adaptability is a key indicator of product reliability.
Synergistic compounding	Compatible with various additives including alkanolamines, borate esters, and sulfonates	Diversified end-user demands make customized compounding formulations the core of differentiated competition.

More notably, facing the historic opportunity brought by lightweighting in the new energy vehicle sector, Vanconol® corrosion inhibitors have achieved synergistic resonance with Tianjin Hi-Perferal’s decade-long technical accumulation in oil and gas field corrosion inhibition: the formulation expertise in amine/imidazoline-type corrosion inhibitors for Cl⁻-containing, high-salinity aqueous media, as developed in the ET series, overlaps significantly with the corrosive factors encountered in EV battery liquid cooling plates and motor cooling systems. This enables low-cost technology transfer and high R&D efficiency.

IV. Application Scenarios and Selection Guide

4.1 Scenario 1: Aluminum Alloy Acid Pickling and Chemical Polishing

Recommended product:Vanconol® SA-90. For acid pickling of aluminum alloy profiles (architectural aluminum, door/window frames) prior to spraying or electrophoresis, and surface cleaning of automotive aluminum alloy wheels, radiators, and other components—SA-90, with its high corrosion inhibition efficiency (>90%) in acidic environments and the thermal stability of Schiff base technology, is the preferred protective solution for acid pickling processes.

4.2 Scenario 2: Aluminum Alloy Machining Fluids (Cutting/Grinding/Lapping)

Recommended Product:Either ALI-910 or ALI-1214 is suitable; ALI-1120 serves as a green upgrade option. Cutting, grinding, and lapping fluids represent the most critical application scenario. During CNC machining of aluminum alloy workpieces, water in the cutting fluid can destroy the passive oxide film on the aluminum surface, leading to gray spots, dark streaks, or even perforation. ALI-910 and ALI-1214, through the dense adsorption protective film formed by phosphate ester groups, effectively inhibit this “electrochemical corrosion under the fluid film,” preserving surface integrity during machining while also providing lubrication to reduce tool wear. For customers with environmental requirements, ALI-1120 offers a fully green, phosphorus-, chromium-, and boron-free solution.

4.3 Scenario 3: Aluminum Alloy Alkaline Cleaning and Degreasing

Recommended Product:ALI-1120 as the primary choice, with ALI-910/ALI-1214 as supplements. In surface treatment processes such as degreasing and alkaline cleaning, the pH of alkaline cleaning solutions typically exceeds 11, which is highly corrosive to aluminum. ALI-1120 is effective over a broad pH range of 7–11, with an optimal pH range of 8.5–10.0, making it an ideal corrosion inhibitor partner for alkaline cleaning systems. For highly alkaline environments (NaOH >100 g/L), ALI-910 is recommended, as it withstands harsh conditions of NaOH <=200 g/L.

4.4 Scenario 4: Corrosion Protection for New Energy Vehicle Thermal Management Systems

Recommended Product Direction:The Vanconol® aluminum alloy corrosion inhibitor series demonstrates broad expansion potential in the corrosion protection of EV battery liquid cooling plates. The new national standard GB 29743.2-2025 imposes strict requirements for electric vehicle coolants, including boron content <=10 mg/kg, Cl⁻ <=10 mg/kg, and pH 7.0–10.0, driving formulation evolution toward high-performance options with no boron, low Cl⁻, and low electrical conductivity (<=100 µS/cm). The technical experience accumulated by the Vanconol® ET series in corrosion and scale inhibition for oilfield produced water (containing Cl⁻, SO₄²⁻, and high salinity) lays a solid foundation for its extension into the new energy vehicle coolant sector.

4.5 Scenario 5: Inter-Process Rust Prevention and Storage

Recommended Product:ALI-1120 (recommended use concentration: 5%–10% aqueous solution). During transitions between machining processes, in-transit storage, or even short-term warehousing, aluminum alloy workpieces may suffer corrosion and discoloration due to ambient humidity and atmospheric moisture. ALI-1120, with its broad pH adaptability and multi-component synergistic effects, forms a stable protective layer during inter-process handling, making it an ideal choice for in-factory rust prevention of aluminum parts.

V. Green Environmental Protection and Sustainable Development

The Vanconol® aluminum corrosion inhibitor series consistently regards green environmental protection as the core orientation of product development. Against the backdrop of increasingly stringent global environmental regulations—EU RoHS/REACH restrictions on hazardous substances, CBAM carbon tariffs on supply chain carbon footprints, and China’s “dual carbon” goals driving green transformation in manufacturing—environmental compliance has evolved from a “bonus point” to a rigid threshold.

Vanconol® SA-90:Completely free of phosphorus and APEO, replacing traditional toxic corrosion inhibitors.

Vanconol® ALI-910/ALI-1214:Free of heavy metals and other restricted substances, readily biodegradable; APEO-free.

Vanconol® ALI-1120:The most environmentally friendly formulation—free of all restricted substances including phosphorus, chromium, boron, and nitrites, representing the highest environmental standard in the Vanconol® series.

VI. Conclusion

From new energy vehicle battery packs to architectural aluminum profiles, from critical aerospace components to lightweight consumer electronics enclosures, the application boundaries of aluminum alloys continue to expand, and the corrosion challenges they face are intensifying. The Vanconol® aluminum corrosion inhibitor series—encompassing the Schiff base pickling inhibitor (SA-90), C9-10 polyether phosphate ester (ALI-910), amino acid/carboxylic acid compounded eco-friendly inhibitor (ALI-1120), and natural fatty alcohol polyether phosphate ester (ALI-1214)—constitutes a comprehensive corrosion protection solution covering the entire aluminum processing value chain.

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Vanconol® remains committed to driving green development through technological innovation. Leveraging over a decade of R&D expertise from Tianjin Hi-Perferal in the field of fine chemicals, we continue to deliver efficient, environmentally friendly, and reliable corrosion protection solutions for the aluminum alloy processing industry. Choosing Vanconol® means choosing a professional guardian that keeps aluminum alloys “in their original condition” for the long term.

For detailed technical specifications, product samples, or inquiries regarding customized formulation solutions, please contact the Metal Corrosion Inhibition Division of Tianjin Hi-Perferal Advanced Materials Co., Ltd.

Website: www.hipfer.com     Service Hotline: Please contact your local sales representative

Tianjin Hi-Perferal Advanced Materials Co., Ltd.

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