Cleaning corrosion coupons is a critical step in corrosion monitoring to ensure accurate weight loss measurements and reliable data. The cleaning process must remove corrosion products without removing any base metal, according to ASTM standards.
Here’s a step-by-step guide on how to clean corrosion coupons properly:
How to Clean Corrosion Coupons
Before You Start
Things You’ll Need:
- Safety gloves and goggles
- Soft brush or sponge
- Acetone or isopropyl alcohol
- Cleaning solution (depends on material and corrosion type)
- Beakers or glass containers
- Analytical balance (precise to 0.1 mg)
- Ultrasonic cleaner (optional)
- Drying oven or desiccator
- Tongs or tweezers
Step 1: Pre-Cleaning Inspection
- Examine the coupon visually for pits, cracks, or deposits.
- Take a photo or document the condition if needed for records.
- Weigh the coupon before cleaning to record the corroded weight.
Step 2: Solvent Cleaning
- Wipe or rinse the coupon with acetoneAnwesend alcohol, or degreaser to remove oils and loose contaminants.
- Dry with a clean lint-free cloth or air dry.
Step 3: Chemical Cleaning (ASTM G1 Method)
Choose a cleaning solution based on the metal type Und corrosion products.
Common Cleaning Solutions:
| Metal Type | Recommended Solution (ASTM G1) |
|---|---|
| Carbon Steel | Clarke’s solution (HCl + Sb2O3 + SnCl2) |
| Edelstahl | Nitric acid solution (HNO₃, 20%) |
| Kupfer/Legierungen | Dilute nitric acid (HNO₃, 50%) |
| Aluminium | Chrom-Phosphorsäure-Gemisch |
- Tauchen Sie den Gutschein in die Lösung für ein 15 seconds to 5 minutes, depending on corrosion severity.
- Sanft Bürste with a soft bristle brush if necessary.
- Gründlich mit ausspülen entionisiertes Wasser after chemical cleaning.
Wichtig: Follow appropriate ASTM G1 cleaning methods and safety protocols. Always work in a fume hood or ventilated area when using acids.
Step 4: Final Rinse and Dry
- Nochmals mit ausspülen acetone oder alcohol to remove water.
- In einem trocknen Warmluftofen oder in einem platzieren Exsikkator to avoid oxidation.
Step 5: Final Weighing
- Once dry and cool, weigh the cleaned coupon using an analytical balance.
- Record the final weight to calculate weight loss Und corrosion rate.
Optional: Ultrasonic Cleaning
- For stubborn corrosion or precision cleaning, use an ultrasonic bath with a mild acid or solvent.
- Do not use ultrasonic cleaning if it risks removing base metal or altering surface condition.
Pro Tips
- Always use non-abrasive tools.
- Ensure coupons are handled with tweezers to avoid contamination.
- Store cleaned coupons in a Exsikkator or sealed bag with desiccant.
Corrosion Rate Formula
After cleaning and weighing, calculate the corrosion rate:
Corrosion Rate (mpy) = (Weight Loss × 534) / (Area × Time × Density)
