Keeping Aluminum Alloys Corrosion-Free

Vanconol Aluminum Alloy Corrosion Inhibitor Technical Guide

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

Tianjin Hi-Perferal Advanced Materials Co., Ltd.

Understanding the “Nemesis” of Aluminum: Corrosion

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

At every stage—metalworking fluids, alkaline cleaners, acid pickling processes, and even routine storage—moisture, oxygen, acidic/alkaline media, and chloride ions from the air can subtly attack the natural oxide protective film (Al₂O₃) on the aluminum surface, causing a range of troublesome issues: loss of luster (dulling), uniform gray or even black discoloration (blackening), white corrosion products (white rust/white deposits), and more destructive localized pitting or intergranular corrosion.

The challenge is even greater in the era of new energy vehicles. Power battery liquid cooling plates use 3003 aluminum alloy and are long-term immersed in ethylene glycol-based coolants; integrated die-cast aluminum parts face high-temperature steam attack during solution heat treatment and quenching; and in aluminum heat exchangers, once corrosion products accumulate in microchannel structures, they can easily block flow paths or cause pinhole leaks.

Facing these challenges, corrosion inhibitors—often called “the simplest, most economical, and most efficient” means of metal corrosion protection—are playing an increasingly critical role for aluminum alloys.

1. How Do Corrosion Inhibitors Protect Aluminum Alloys?

1.1 Working Principle of Corrosion Inhibitors

Corrosion inhibitors are chemical substances that, when present in appropriate concentrations in a corrosive medium, adsorb onto the metal surface and significantly reduce the corrosion rate. The core principles can be summarized in three aspects:

Physical or chemical adsorption: Polar groups (–OH, –COOH, –NH₂, etc.) of the inhibitor molecule orient themselves and adsorb onto active sites of the oxide film on the aluminum surface, like putting a “molecular protective suit” on the metal.

Formation of a barrier film: Inhibitor molecules form a dense protective layer between the metal surface and the corrosive medium, physically blocking water, oxygen, and aggressive ions from direct contact with the metal substrate.

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

1.2 Vanconol’s Core Corrosion Inhibition Technologies

The Vanconol aluminum alloy corrosion inhibitor series covers three core technology routes, providing targeted protection for different application scenarios:

First, Schiff Base Technology (Vanconol SA-90): Schiff bases are organic compounds containing imine (C=N) unsaturated bonds. Their molecular structure contains heteroatoms such as nitrogen (N) and oxygen (O) along with C=N bonds, enabling chemical adsorption onto the aluminum surface to form a dense, stable protective film. In 5% acid media, SA-90 achieves a corrosion inhibition rate consistently above 90%, while offering thermal stability and a wide temperature range (20 °C to 60 °C). Moreover, its formulation is completely free of phosphorus and APEO (alkylphenol ethoxylates), making it a suitable option for replacing traditional toxic corrosion inhibitors.

Second, Phosphate Ester Technology (Vanconol ALI-910 / ALI-1214): Phosphate ester corrosion inhibitors are the mainstream technology in today’s aluminum processing fluid market. Their molecular structure combines the strong adsorption and chelating ability of the phosphate group (–PO₃H₂) with the excellent water solubility and permeability of polyether chains. The phosphate group rapidly chelates with the aluminum surface to form a hydrophobic, dense monolayer protective film; the long polyether chains impart outstanding permeability and coverage over complex workpiece geometries. ALI-910 is based on C9-10 polyether, while ALI-1214 uses natural fatty alcohol polyether as raw material. Both exhibit high resistance to strong alkali (NaOH ≤ 200 g/L), high temperatures (≤ 90 °C), and hard water, maintaining stability across a wide pH range of 6–12.

Third, Amino Acid / Carboxylic Acid Blend Technology (Vanconol ALI-1120): This represents Vanconol’s forward-looking position in the field of environmentally friendly aluminum corrosion inhibitors. ALI-1120 is carefully formulated from amino acids and carboxylic acid compounds, and is completely free of restricted substances such as phosphorus, chromium, boron, and nitrites. The selected components exhibit a significant synergistic corrosion inhibition effect—organic molecules adsorb onto active sites of the oxide film via functional groups to form a hydrophobic barrier film, while certain components react with magnesium ions to form a dense passivation layer, strengthening substrate protection. This dual “adsorption + passivation” mechanism delivers overall corrosion protection superior to any single component, and provides excellent protection for aluminum and its alloys across series 1xxx, 2xxx, 5xxx, 6xxx, and others.

2. 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, processing fluids, cleaning agents, and in-process rust prevention. The following table compares key parameters for each product:

Product	Core Chemistry	Recommended Dosage	Primary Applications
Vanconol SA-90	Schiff base derivative	0.1%–0.3%	Aluminum alloy acid pickling, chemical polishing
Vanconol ALI-910	C9-10 polyether phosphate ester	1%–5%	Aluminum processing fluids, cleaners
Vanconol ALI-1120	Amino acid/carboxylic acid blend	2%–10%	Alkaline cleaners, in-process rust prevention
Vanconol ALI-1214	Natural fatty alcohol polyether phosphate ester	0.2%–3%	Forming lubrication, anti-corrosion chemicals

Detailed technical specifications for each product are as follows:

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

Vanconol SA-90 is designed specifically for corrosion protection of aluminum alloys in acidic environments. Its core advantage is a corrosion inhibition rate consistently exceeding 90% in common pickling acids such as 5% sulfuric, hydrochloric, or nitric acid, effectively suppressing over-etching, 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.

Applications: Acid pickling prior to coating/electrophoresis of aluminum profiles (architectural profiles, window/door frames); surface cleaning of automotive aluminum alloy wheels, radiators and other parts; acid pickling of electronic product aluminum housings and heat sinks; maintenance cleaning of aircraft aluminum components.

Usage: Recommended addition level: 0.1%–0.3% (i.e., 1–3 kg of product per 1000 L of pickling bath). It is advisable to add the product into the pickling tank first, circulate to homogeneity, then introduce the acid solution; it can also be continuously dosed into the working pickling solution.

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

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

Technical specifications: Appearance: colorless to pale yellow transparent viscous liquid; solid content ≥ 95%; pH (2% aqueous solution) ≤ 3.0; ionic type: anionic; acid value 280–320 mg KOH/g; phosphorus content 6%–8%; resistant to strong alkali (NaOH ≤ 200 g/L), high temperature, and hard water; not easily hydrolyzed.

Applications: Aluminum processing fluids (cutting, grinding, lapping fluids—as rust inhibitor/corrosion inhibitor); metal cleaners and pretreatment (degreasers, cleaning solutions— as corrosion-inhibiting component); forming processes and specialty lubrication (cold rolling emulsions, stamping fluids, wire drawing oils, lubricant formulations—as corrosion inhibitor/extreme pressure additive).

Recommended addition level: 1%–5% in aluminum processing fluid formulations. The exact dosage should be confirmed through testing based on water hardness, processing severity, and rust prevention requirements.

Reference blend 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 prevention) + coupling agent (e.g., isopropyl alcohol, 2%) + deionized water (balance). Use under weakly alkaline conditions (pH 8.0–9.5) for optimal corrosion inhibition. Long-term operating temperature is recommended not to exceed 80 °C.

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

ALI-1120 is Vanconol’s next-generation environmentally friendly aluminum corrosion inhibitor, developed in response to the global trend toward green chemicals. It features a “phosphorus-free, chromium-free, boron-free” green formulation, aligned with the most stringent environmental regulations.

Technical specifications: Appearance: colorless to pale yellow transparent liquid; active content 40 ± 2%; density (20 °C) 1.10–1.15 g/cm³; pH (1% aqueous solution) 7.0–10.5; completely water-soluble.

Applications and recommended dosages: Metalworking fluids (cutting, grinding of aluminum and its alloys), recommended addition 3%–8%; alkaline cleaners (degreasing and cleaning aluminum components), recommended addition 2%–5%; in-process rust prevention (can be used as an in-process rust preventive solution), recommended concentration 5%–10% aqueous solution.

Usage: It is recommended to add the product into water first when preparing the working solution, stir thoroughly before adding other components. For best results, use deionized water. The optimal pH range is 8.5–10.0, and it is 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 produced by phosphorylation of natural fatty alcohol polyether, combining the excellent performance of ALI-910 with improved environmental compatibility and multi-functional synergy.

Technical specifications: Appearance: colorless to slightly yellow paste; solid content ≥ 95%; pH (2% aqueous solution) ≤ 3.5; acid value 120–140 mg KOH/g; phosphorus content 3%–5%; easily soluble in water, ethanol, and ethylene glycol; ionic type: anionic, compatible with nonionic and amphoteric surfactants.

Key features: Wide environmental adaptability—resistant to acids, alkalis (pH 6–12), and hard water; remains active at ≤ 90 °C and in high inorganic salt environments. Multi-functional synergy—it also provides lubrication, emulsification, dispersion, and antistatic properties, potentially reducing the need for other additives in processing fluid formulations and lowering overall formulation cost.

Recommended addition level: 0.2%–3% in aluminum processing fluid formulations. Reference blend: 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 Corrosion Inhibitors

In an increasingly competitive market for aluminum corrosion inhibitors, what sets the Vanconol series apart? The following table highlights six key dimensions:

Dimension	Vanconol ALI Series Advantage	Industry Background & Needs
Environmental Compliance	Free of phosphorus, chromium, APEO; RoHS/REACH compliant	EU CBAM driving full-lifecycle carbon reduction for aluminum; phosphorus-containing corrosion inhibitors facing regulatory phase-out
Broad pH	ALI-910 resistant to strong alkali (NaOH ≤ 200 g/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 becoming widespread
Temperature Tolerance	Stable operation ≤ 90 °C (ALI-910/ALI-1214)	Growth of high-temperature processes such as integrated die-casting demands higher thermal stability from corrosion inhibitors
Hard Water Compatibility	Hard water resistant, low saponification tendency (ALI-910/ALI-1214)	Water quality varies significantly across metalworking sites; hard water tolerance is a key reliability indicator
Blending Synergy	Compatible with alkanolamines, borate esters, sulfonates, and many other additives	Diverse end-user needs make customized blended formulations a core differentiator

Notably, in response to the historic opportunity presented by lightweighting in new energy vehicles, Vanconol’s corrosion inhibitors synergize with more than a decade of technical expertise from Hi-Perferal in the oilfield corrosion inhibitor field. The experience accumulated with organic amine / imidazoline corrosion inhibitors for media containing Cl⁻ and high salinity (from the ET series) overlaps heavily with the corrosive factors faced by EV battery cooling plates and motor cooling systems—enabling efficient technology transfer and R&D.

4. Application Scenarios and Selection Guide

4.1 Scenario 1: Aluminum Acid Pickling & Chemical Polishing

Recommended product: Vanconol SA-90. For aluminum profile manufacturing (architectural profiles, window/door frames) prior to coating/electrophoresis pickling; surface cleaning of automotive aluminum alloy wheels, radiators, etc.—SA-90, with its high corrosion inhibition rate (>90%) in acidic environments and the thermal stability of Schiff base technology, is the preferred protection for pickling processes.

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

Recommended products: ALI-910 or ALI-1214 for standard requirements; ALI-1120 as a green upgrade option. Cutting, grinding, and lapping fluids are the most central application scenario. During CNC machining, water in the cutting fluid can destroy the passivated oxide film on the aluminum surface, leading to gray spots, dark streaks, or even pitting on the workpiece. With the dense adsorbed protective film formed by phosphate ester groups, ALI-910 and ALI-1214 effectively suppress this “electrochemical corrosion under the liquid film,” preserving surface integrity during processing while also providing lubrication to reduce tool wear. For customers with the highest environmental requirements, ALI-1120 offers a completely phosphorus-, chromium-, and boron-free green solution.

4.3 Scenario 3: Aluminum Alkaline Cleaning & Degreasing

Recommended products: Primarily ALI-1120; ALI-910/ALI-1214 as secondary options. During degreasing, alkaline washing, and other surface treatment steps, the pH of alkaline cleaning solutions can exceed 11, which is highly corrosive to aluminum. ALI-1120 is effective over a broad pH range of 7–11, with optimal performance at pH 8.5–10.0, making it a suitable corrosion inhibitor for alkaline cleaning systems. For highly alkaline environments (NaOH > 100 g/L), ALI-910 is recommended, as it can withstand NaOH up to 200 g/L.

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

Recommended product direction: The Vanconol aluminum corrosion inhibitor series shows promising potential for battery liquid cooling plate protection in new energy vehicles. China’s new standard GB 29743.2-2025 imposes strict requirements for electric vehicle coolants: boron ≤ 10 mg/kg, Cl⁻ ≤ 10 mg/kg, pH 7.0–10.0, driving formulation iteration toward boron-free, low-Cl⁻, low-conductivity (≤ 100 µS/cm) high-performance formulations. The experience accumulated with the Vanconol ET series in oilfield produced water (containing Cl⁻, SO₄²⁻, high salinity) corrosion inhibition and scale control provides a solid technical foundation for extending into the new energy vehicle coolant field.

4.5 Scenario 5: In-Process Rust Prevention Storage

Recommended product: ALI-1120 (recommended concentration 5%–10% aqueous solution). During storage between machining steps, temporary holding, or even short-term warehousing, aluminum workpieces can suffer corrosion discoloration due to environmental humidity and moisture in the air. With its broad pH adaptability and multi-component synergistic effect, ALI-1120 forms a stable protective layer in-process, making it a suitable choice for protecting aluminum parts during factory transfer and temporary storage.

5. Green Chemistry and Sustainable Development

The Vanconol aluminum corrosion inhibitor series has always prioritized green chemistry in product R&D. Against the backdrop of increasingly stringent global environmental regulations—including EU RoHS/REACH restrictions on hazardous substances, CBAM carbon tariffs tracking supply chain carbon footprints, and China’s “dual carbon” goals driving green transformation in manufacturing—environmental compliance has shifted from a “plus factor” to a hard requirement.

Vanconol SA-90: Completely phosphorus-free and APEO-free, serving as a replacement for 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 ultimate green formulation—free of all restricted substances including phosphorus, chromium, boron, and nitrites, making it the highest environmental standard product in the Vanconol series.

6. Conclusion

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

Vanconol® remains committed to driving green development through technological innovation, leveraging more than a decade of R&D expertise in fine chemicals at Tianjin Hi-Perferal to deliver efficient, environmentally responsible, and reliable corrosion protection solutions for the aluminum processing industry. Choosing Vanconol means choosing a professional guardian that keeps aluminum “true to its original color.”

For detailed technical data sheets, samples, or custom blended formulations, please contact the Metal Corrosion Protection Division of Tianjin Hi-Perferal Advanced Materials Co., Ltd.

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Tianjin Hi-Perferal Advanced Materials Co., Ltd.