Uneven or missing film
- Likely causes
- Contamination, weak activation or off-spec pH/concentration/temperature
- First checks
- Compare pretreatment cleanliness with bath analysis first
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Products & Solutions · 05
Conversion coating
Phosphate, chromate and zincate treatments for steel, zinc and aluminum are reviewed with pretreatment and downstream processes.
PROCESS OVERVIEW
Product review starts with process conditions
Conversion coatings create a protective layer or a base for subsequent plating or painting through surface reactions. Cleanliness, bath condition, rinsing and drying determine uniformity and corrosion resistance.
Suitability is reviewed with the substrate, upstream and downstream stages, control items, and required finish—not by product name alone.
- Applicable substrates & targets
- Steel and iron · Zinc and zinc-plated surfaces · Aluminum and its alloys · Copper and copper alloys · Substrates before painting or plating
- Application scope
- Phosphate coating · Chromate conversion · Aluminum conversion treatment · Zincate pretreatment · Pre-paint or pre-plate coating
CONTROL POINTS
Key control items to review before application
Current settings and recent changes help establish a more useful inspection sequence.
- 01Surface cleanliness and activation
- 02pH, concentration and temperature
- 03Treatment time
- 04Rinse quality and carry-over
- 05Coating weight and appearance
- 06Drying condition
- 07Corrosion and adhesion
TROUBLESHOOTING
Common issues and first checks
One symptom can involve several process factors, so likely causes and the inspection sequence are reviewed together.
Poor adhesion
- Likely causes
- Excess film, rinse residue, drying or downstream delay
- First checks
- Review coating weight, rinsing, drying and waiting time
Low corrosion resistance
- Likely causes
- Insufficient film, incomplete sealing or surface defects
- First checks
- Compare coating quality, post-treatment and localized corrosion
TECHNICAL SUPPORT
PLACHEM support scope
Field conditions and defect symptoms are used to organize the items that should be checked first.
- 01Substrate-specific process and chemistry review
- 02pH, concentration, temperature and coating-weight controls
- 03Cause classification for adhesion, appearance and corrosion
- 04Review of pretreatment, rinse, drying and downstream stages
Discuss application conditions for Conversion coating
Share the substrate, process sequence, chemicals in use, control values, defect symptoms, or required documents.