1.What is the most commonly used and applicable on-site rapid test?
Cross-cutting method
Tools: Single-edged/multi-edged cross-cutting knife (blade distance 1mm/2mm/3mm)
3M 600 tape (width 25mm, adhesion 10N/25mm)
20x magnifying glass
Grid operation: Cut a 6×6 grid on the coating surface (deep to the substrate)
After cutting, lightly brush the surface to remove debris
2.What are the steps of the tension method?
Sample preparation: Glue a 20mm diameter aluminum ingot to the coating surface with epoxy glue and cure for 24 hours (23℃±2℃, humidity 50%±5%)
Tensile test: Use a digital tensile machine to stretch vertically until it falls off. Speed 1mm/min, record the peak force value (MPa)
3.What are the steps of the bending method?
Tool: Conical shaft bending tester.
Operation: Bend the sample 180° around the axis; observe the cracking of the coating at the bend.
Judgment: No cracks: excellent adhesion (PVDF coating should pass the Ø6mm test)
Fine lines ≤ 0.5mm: qualified (HDP coating Ø10mm)
Delamination/fracture: unqualified
4.What are the steps for the boiling water method?
Steps: Immerse the sample in boiling water (100℃) for 2 hours; take it out and wipe it dry, and then immediately perform a cross-cut test. Qualification standard: Adhesion reduction rate after boiling ≤20%; Cross-cut level does not exceed level 2.
5.What is the principle of electrolysis?
Principle: Power is applied in 3% NaCl solution (6V DC); Observe the coating for blistering after the cathodic protection fails. Standard: Adhesion is considered acceptable if there is no blistering within 72 hours.