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Root Causes of Weld Corrosion in Carburetor Cleaner Aerosol Cans: 28-Day Erosion Comparison Test of Four Coating Processes and Material Selection Standards
2026-05-08
Weld corrosion of carburetor cleaner aerosol cansis the primary cause of batch leakage, storage deterioration and terminal returns of finished cans. SAILON, a professional manufacturer of custom tinplate Aerosol Cans, has conducted a 28-day high-temperature and strong alkali immersion comparison test on four mainstream weld repair coating processes in the industry. The measured data shows that ordinary liquid coating develops weld rust spots and coating blisters on the 5th day, single-layer powder coating fails successively from the 9th to the 17th day, and only the double-layer powder reinforced coating with a film thickness of more than 35μm remains intact throughout the test, with the iron ion migration concentration lower than the instrument detection limit, which can long-term adapt to the storage conditions of high pH alkaline carburetor cleaners.
Most chemical packaging practitioners know that carburetor cleaners can quickly decompose engine carbon deposits and oil sludge colloids, relying on the synergistic effect of sodium hydroxide, organic strong alkalis and organic solvents in the formula. However, few people delve into the fact that such strongly corrosive contents do not erode the entire can body evenly, but accurately target the weak area of Tinplate Can weld repair coating. The microscopic defects generated by high-temperature welding on the weld area cannot be detected by naked eyes or conventional air tightness tests, which will gradually induce a series of quality problems such aspinhole corrosion, coating peeling and iron ion migration during long-term storage, becoming the key reason for unstable mass production quality of auto maintenance aerosol cans.
Four Key Nodes of Strong Alkali Content Eroding Tinplate Welds
Combined with the full-cycle observation of this 28-day experiment, we disassembled the whole process of strong alkali medium corroding carburetor cleaner cans into four irreversible induction nodes, restoring the microscopic corrosion logic in full:
- Node 1: Failure of Tin Plating Layer Dissolution: The high-alkaline cleaning solution preferentially dissolves the tin plating protective layer on the tinplate surface upon contact. Areas with insufficient tin plating thickness or uneven coating will lose protection rapidly, exposing the poorly corrosion-resistant tin-iron alloy transition layer and opening the channel for subsequent deep corrosion.
- Node 2: Accelerated Corrosion of Weld Residual Stress: The instantaneous high temperature during can welding completely changes the metallographic structure of the metal around the weld and leaves a large amount of residual internal stress. Under the superposition of strong alkali medium and stress, micro corrosion cracks grow on the metal surface, and the corrosion rate is 3-5 times faster than that of the flat area of the can body.
- Node 3: Penetration Erosion via Repair Coating Pinholes: The inherently uneven texture of welds prevents full coverage by conventional liquid spraying and single-layer powder spraying, easily forming thin coating areas and invisible pinholes. Micro defects in the weld inner coating act as penetration channels, allowing strong alkali liquid to directly pass through the coating and erode the internal carbon steel substrate.
- Node 4: Lateral Diffusion at Interface: This is the most overlooked hidden corrosion hazard. Even if the repair coating on the weld is intact, if the alkali resistance of the main inner coating of the can body is substandard, the strong alkali liquid will spread laterally along the bonding interface between the inner coating and the metal, erode the weld edge from the side, and eventually cause the failure of the overall protection system.
Strict Experimental Design: Restore Real Storage Corrosion Conditions
To avoid data deviation caused by conventional short-term room temperature tests, this experiment adopts an accelerated aging test scheme instead of traditional detection modes, accurately simulating long-term high-temperature, closed and humid storage environments. All test samples are made of the same batch of primary T2.5 tinplate mother coils with unified can-making parameters, only differing in coating processes to ensure a single experimental variable.
The core rigorous design of this experiment, which is also the gold standard for industrial working condition verification:
- 50℃ constant temperature environment: The high-temperature accelerated corrosion factor is about 8-10 times that of room temperature, and 28-day continuous testing restores the natural corrosion state of 8-10 months of room temperature storage;
- Inverted can immersion method: Ensure the alkaline carburetor cleaner completely covers the can mouth crimping area and the entire weld, eliminating air gap blind spots without protection dead zones;
- Three precise detection methods: Metallographic microscopic observation of coating corrosion depth, ICP-MS instrument quantitative detection of iron ion migration, and cross-cut test for coating adhesion attenuation, to fully quantify the corrosion grade.
Basic Parameter Comparison Table of Four Weld Repair Coating Processes
| Process Group | Coating Type | Curing Film Thickness | Curing Temperature Curve | Adaptable Content Properties |
|---|---|---|---|---|
| Group A | Single ordinary liquid spray coating | 8-12μm | 180℃ constant temperature insulation for 10min | Weak solvent, neutral daily chemical spray |
| Group B | Single-layer electrostatic powder thick film coating | 25-30μm | 200℃ constant temperature curing for 12min | Weak alkaline general maintenance spray |
| Group C | Single-layer electrostatic powder thin film coating | 15-20μm | 200℃ constant temperature curing for 12min | Slightly corrosive daily aerosol products |
| Group D | Electrostatic powder double-layer reinforced coating | 35-42μm | 200℃ curing + 190℃ secondary leveling | High alkalinity auto maintenance aerosol cans |
28-Day Long-Term Erosion Test Comprehensive Data Statistics Table
| Process Group | Rust Spot Occurrence Cycle | Coating Corrosion Depth | Iron Ion Migration Concentration | Coating Retention Rate | Long-Term Storage Adaptability |
|---|---|---|---|---|---|
| Group A | Weld bubbles and rust spots on day 4-5 | 86-90μm | Greatly exceeding the standard | Below 30% | Not suitable for alkaline formulas |
| Group B | Local slight discoloration on day 16-18 | 30-35μm | Close to safety critical value | 75%-80% | Only suitable for low alkalinity formulas |
| Group C | Continuous coating peeling on day 9-11 | 62-68μm | Significantly exceeding safety standard | 40%-48% | Completely unsuitable for strong alkaline media |
| Group D | No rust spots or coating peeling throughout the cycle | Almost no depth erosion | Below instrument detection limit | Above 98% | Compatible with all high alkalinity stock solutions |
In-Depth Interpretation of Experimental Data Inflection Points
From the full-cycle corrosion data changes of the four groups of samples, we can clearly capture the performance inflection points of different coating processes, which are the core basis for material selection and process determination of chemical aerosol cans:
Group A conventional liquid coating fails the fastest, with weld corrosion problems occurring in only 5 days and iron ion concentration exceeding the standard significantly. It proves that liquid spraying process has poor compactness and cannot resist continuous erosion of strong alkali media. It is only suitable for neutral and weakly corrosive ordinary daily chemical spray cans, and is absolutely not applicable to mass production of carburetor cleaner aerosol cans.
The comparison between Group B and Group C confirms the core performance rule of powder coating: the protection capacity is highly dependent on the cured film thickness. The thin-film powder coating of 15-20μm has a weak protective barrier, and coating peeling occurs in less than 10 days; the thick-film powder of 25-30μm can effectively delay the corrosion rate and postpone the failure time to more than 16 days. Even so, single-layer thick powder coating cannot eliminate micro defects at weld corners, and there are still hidden leakage risks in long-term storage, failing to meet the long-term storage requirements of high alkalinity carburetor cleaners.
Group D double-layer powder reinforced coating is the only optimal solution in this experiment. The 35-42μm double-layer composite coating seals the micro pinholes of the base layer through primary powder curing, and reinforces weak positions such as weld corners and interfaces through secondary precise coating, completely eliminating protection blind spots. It finally achieves zero corrosion and zero penetration under high-temperature and strong alkali environment for 28 days, perfectly meeting the production needs of all kinds of strong alkaline chemical tinplate aerosol cans.
Industry Standardized Material Selection and Process Internal Control Standards
Based on measured experimental data, SAILON has sorted out a set of implementable enterprise-level standards for material selection, production and testing, covering the whole dimensions of base material, coating, process and factory testing, suitable for the production of all high-alkalinity auto maintenance aerosol cans:
| Test Item | Index Requirement | Test/Verification Method |
|---|---|---|
| Weld Coating Width | ≥8mm | Cut the weld section of the can and measure the average value at multiple points with a vernier caliper |
| Cured Coating Film Thickness | ≥35μm (double-layer powder system) | Use coating thickness gauge to measure 5 key points of weld and take the average value |
| Can Body Inner Coating Alkali Resistance | No blistering, peeling or discoloration after 24h immersion in 5% NaOH solution | Constant temperature immersion test + cross-cut adhesion retest |
| Tinplate Substrate Grade | Primary T2.5 tinplate with qualified tin plating | Supplier quality certificate + incoming sampling inspection of tin plating amount |
| Factory Weld Full Inspection | Zero pinholes and zero defects in coating area | 100% on-line high-voltage spark leak detection with voltage calibrated according to film thickness |
| Mass Production Verification | Iron ion migration ≤1ppm after 28-day inverted immersion at 50℃ | ICP-MS quantitative detection + metallographic section microscopic confirmation |
Professional FAQ Practical Q&A
In view of the high-frequency questions of customers in custom tinplate aerosol cans, strong alkali can selection and quality control, we have sorted out practical answers combined with experimental data:
Q1: Why do carburetor cleaner aerosol cans of the same model have great differences in corrosion resistance among different production batches?
A: The corrosion resistance difference of cans with consistent external dimensions mainly comes from the quality control differences of substrate grade, inner coating material and weld coating process. Some manufacturers downgrade substrate and coating specifications to reduce costs, which shows no obvious problems in short-term room temperature storage, but will quickly cause corrosion and leakage in high-temperature and high-humidity environments. Especially for cans after long-distance transportation, high humidity will further amplify hidden defects of substrates and coatings, which cannot be predicted by appearance inspection alone. Only standardized whole-process processes can ensure batch stability.
Q2: Can single-layer thick-film powder coating replace double-layer coating for mass production of high alkalinity auto maintenance aerosol cans?
A: It cannot be replaced completely. Single-layer thick-film powder only increases the basic coating thickness, but cannot eliminate micro pinholes and stress defects at weld corners and interfaces. After long-term contact with strongly corrosive contents, corrosion will gradually spread from hidden weak points, eventually causing coating peeling and can leakage. The core advantage of double-layer secondary coating is to target and block all process blind spots, with far higher protection stability than single-layer technology.
Q3: How to accurately identify whether the manufacturer's process is suitable for strong alkali carburetor cleaner contents when customizing tinplate aerosol cans?
A: Do not only refer to the manufacturer's nominal parameters. You can require the can manufacturer to provide three core measured reports to judge the adaptability accurately: ① Inner coating alkali resistance test report (24-hour immersion measured data of 5% NaOH); ② Batch measured data of weld coating film thickness (multi-point average value, not theoretical nominal value); ③ 50℃ 28-day inverted accelerated aging test report, including iron ion migration concentration, coating metallographic photos and coating retention rate data. SAILON provides one-to-one adaptive testing and process customization services according to customers' exclusive cleaner formulas, avoiding batch quality problems from the source.
In the auto maintenance chemical packaging industry, the iteration speed of formulas is accelerating continuously, and traditional can-making experience can no longer adapt to new high-alkalinity and strong-corrosion cleaner products. With years of in-depth experience in custom tinplate aerosol cans, SAILON always takes measured experimental data as the core R&D basis, strictly implements high-standard material selection and process specifications, and provides stable, long-term and zero-hidden-danger can packaging solutions for various auto maintenance aerosol cans and strong alkali chemical aerosol products. Feel free to contact us for customized cooperation.