CHEMEON eTCP POWDER
RoHS, WEEE, ELV and OSHA PEL Compliant Trivalent Chromium Conversion Coating Used for Immersion and Spray Applications
PRIMARY APPLICATION
CHEMEON eTCP POWDER is a chemical conversion coating for aluminum, magnesium, zinc and their alloys. It produces a protective coating, which minimizes corrosion as well as improves adhesion capabilities of the surface. The CHEMEON eTCP POWDER conversion coating has a noticeable blue to purple color
which provides visual verification that the coating has been applied. Corrosion resistance is improved as compared to conventional trivalent chromate pretreatments.
Applications include:
• Hexavalent chromium-free conversion coating on aluminum, magnesium, zinc and their alloys
• Noticeable color change
• Unpainted corrosion protection on aluminum that is comparable to hexavalent chromium
• Meets contact electrical resistance requirements of MIL-DTL-81706B
• Pretreatment for paint and powder coat applications, which results in extended corrosion resistance
• Field touch-up for chromate and anodic coatings
• Seal for anodic coatings on aluminum, including Type II B thin film and Type II colorless, dyed, and
electrolytically-colored coatings
• Re-coat stripped substrates such as aircraft
• Provides a noticeable blue to purple color which provides visual verification that the coating has been
applied
CHEMEON eTCP POWDER meets the following specifications: MIL-DTL-81706B (Qualifying Specification for MIL-DTL- 5541), Type II (non-hexavalent chromium), Class 1A and Class 3, Form 1 (Liquid), Methods A (spray), B (brush) and C (immersion) as well as MIL-DTL-5541, Type II, Class 1A and Class 3, Methods A, B and C. CHEMEON eTCP POWDER has a Qualification Dataset (QDS) on the DoD’s online Qualified Products Database (QPD) for Type II, both Class 1A and Class 3, Methods A, B and C. CHEMEON eTCP POWDER has the following U.S. Patent: 10,533,254.
CHEMICAL CHARACTERISTICS
Chemical Composition ………………….Trivalent Chromium, Activators
Appearance…………………….Dark Brown Powder
Odor …………………………..None to mild
Bulk Density …………………..1.110 g/cm3 (20 °C)
Freeze/Thaw Stable…………………Yes
APPLICATION PROCEDURE
General Operating Conditions for Use as a Chemical Conversion Coating:
Application…………………….Immersion, spray or brush
Concentration………………..6 – 10 g/L (8 g/L is optimal)
Water Quality …………………..Deionized (DI) or reverse osmosis (RO) is preferred
Temperature…………………..65° – 90 °F
Time …………………….1 – 15 minutes. 5 – 6 minutes typical
pH……………….3.6 – 4.0, optimum 3.85
pH Decrease ……………..Gardacid SO4 or sulfuric acid diluted to 5 – 10%
pH Increase……………………Gardobond-Additive H 7212 or caustic soda 5 – 10%
General Operating Conditions for Use as a Seal for Anodic Coatings on Aluminum:
Application…………………Immersion
Concentration………………….6 – 10 g/L (8 g/L is optimal)
Water Quality ……………….Deionized (DI) or reverse osmosis (RO) is preferred
Temperature……………65° – 85 °F
Time ……………………..1 – 15 minutes (2 – 5 min typical). Do not agitate tank
during sealing
pH………………………….3.6 – 4.0 (3.8 – 3.9 ideal)
pH Decrease ……………..Gardacid SO4 or sulfuric acid diluted to 5 – 10%
pH Increase………………Gardobond-Additive H 7212 or caustic soda 5 – 10%
Notes for Use as a Conversion Coating on Aluminum:
To achieve optimum results, the aluminum substrate must be cleaned and activated prior to treatment with CHEMEON eTCP POWDER.
Excellent results have been obtained using a mild alkaline cleaner at the lower end of its operating temperature range. Typically, etching cleaners do not perform as well in applications where good unpainted corrosion resistance is needed. One suggested immersion cleaner is Aluminum Cleaner NST.
Non-silicated cleaners are preferred.
After cleaning and rinsing, surface activation should be performed using a strong acid such as 50% nitric acid. A less concentrated acid product with additives such as Ardrox 295GD may also be used.
The pH of a CHEMEON eTCP POWDER bath should be carefully monitored. At no time should the pH of the bath be allowed to rise above 4.0. All pH adjustments should be made slowly and with strong agitation to ensure complete and rapid mixing. Good agitation is required when increasing pH in order to minimize localized precipitation.
During immersion applications, the CHEMEON eTCP POWDER bath should not be agitated.
After coating in CHEMEON eTCP POWDER, parts should be thoroughly rinsed. DI or RO water is preferred.
Peak metal temperature for dry off should not exceed 350 °F.
Typical coating weights range from 20 to 45 mg/sq ft.
Age coated but unpainted panels 24 hours prior to exposing to Neutral Salt Spray testing.
For spray applications on alloy 2024T3 for MIL-DTL-5541, contact the CHEMEON Technical Center at 1-888-782-8324 or tcp_info@CHEMEON.com.
For applications on previously-coated and stripped substrates or touch-up field repairs, contact the CHEMEON Technical Center at 1-888-782-8324 or tcp_info@CHEMEON.com.
Notes for Use as a Field Touch-Up on Aluminum:
Thoroughly clean with an abrasive pad such as 3M Scotch-Brite, rinse, apply CHEMEON eTCP POWDER in a solution of 10 g/L, pH 3.6 – 4.0 at ambient temperature for 10 minutes and rinse.
Notes for Use as a Conversion Coating on Magnesium and Zinc:
For specific applications and process parameters contact the CHEMEON Technical Center at 1-888-638-2527 or tcp_info@CHEMEON.com
Notes for Use as Seal for Anodic Coatings on Aluminum:
The anodized aluminum must be rinsed well before immersion in the CHEMEON eTCP POWDER seal.
After treatment, only 10 – 30 seconds in clean, room temperature water is suggested for a post-seal rinse.
For use with dyed surfaces, excluding those that have been electrolytically modified, use a low concentration of CHEMEON eTCP POWDER with a long immersion time to obtain maximum color retention.
For electrolytically-colored coatings, the best results are achieved by using a high concentration of CHEMEON eTCP POWDER with a mid-range immersion time.
Performance on Anodized Aluminum
For all concentrations and immersion times outlined in the General Operating Conditions section of this Technical Information sheet, CHEMEON eTCP POWDER will provide neutral salt spray resistance in accordance with ASTM B 117 to 3,000 hours or more on the anodized, eTCP POWDER sealed surface.
For application of organic coatings on top of the anodized surface, the eTCP POWDER sealed surface provides an excellent base for adhesion purposes.
Bath Make-Up:
Note: Before inital charge, thoroughly clean the tank
For a 100 Gallon bath at 8 g/L (optimum concentration)
1. Fill the tank half full with deionized (DI) or reverse osmosis (RO) water.
2. Slury 3028 g (6.67 lbs) eTCP Powder in a bucket with water.
3. Add the slurry to the tank.
4. Fill the tank to the operating level with deionized (DI) or reverse osmosis (RO) water.
5. Mix 1 – 3 hours.
6. Allow solution to stand with or without mixing overnight (initial makeup only. Mixing perferred)
7. Adjust the pH of the bath to the operating range(3.8 to 3.9). It should normally be necessary to add a pH-increasing material specified previously. Slowly add small amounts with good mixing. At no time should the bath pH be allowed to rise above 4.0.
Used Baths:
Over time, a small amount of precipitate may form in the tank. This is normal. If the pH of the solution rises above 4.0, an unacceptably large amount of precipitate may form. Do not filter this out because the precipitate has active ingredients that are needed.
Contact the CHEMEON Technical Center for assistance in re-dissolving the precipitate.
Bath Maintenance:
• The pH of the bath should be checked regularly. At no time should the pH be allowed to rise above 4.0.
• Replenishment due to drag out should be made with CHEMEON eTCP POWDER in water at the same concentration that the bath was originally made up at. For example, if the bath is made up at an 8 g/L concentration, drag out should be replenished with a 8 g/L solution of CHEMEON eTCP POWDER.
• Measurement of the bath concentration may be accomplished by using spectrophotometry. Analysis by titration is not accurate and not recommended.
The CHEMEON eTCP POWDER technical service group provides free monthly evaluation of concentration and pH. Please contact the CHEMEON Technical Center at 1-888-638-2527 or tcp_info@CHEMEON.com if you are interested in this service.
SOLUTIONS CONTROL BY SPECTROPHOTOMETRY
Equipment:
• Spectrophotometer
• Quartz or plastic cuvette
• Plastic pipettes
• Analytical Balance
• Graduated cylinder
• 100 ml volumetric flask
• 1L plastic storage bottles
• 0.45 micron filters x 1 per bath sample
• Fine porosity filter paper such as Whatman 40 x 1 per bath sample
• Graphing software or the ability to calculate the equation of a line
Using a spectrophotometer is an accurate way to measure the concentration of a CHEMEON eTCP POWDER bath. CHEMEON eTCP POWDER standards should be made in sets of three at concentrations that bracket the target concentration of the bath. For example, if the operating concentration is 8 g/L, your
standards should be 4g/L, 8 g/L, and 12 g/L.
Procedure for Making One Liter 4 g/L, 8 g/L, and 12 g/L Standards:
1. To make a 12 g/L standard, use an alalytical balance to weigh out approximately 1.2 g of
CHEMEON eTCP POWDER. Record the widht to the nearest miligram. Transfer completely to the
100 mL volumetric flask.
2. Fill the volumetric flask to the 100 mL mark with deionized water.
3. Put the cap on and mix thoroughly.
4. Pour the contents into a plastic storage bottle and label the bottle with the date and concentration.
5. Repeat steps 2 – 5 for the 8 g/L and 4 g/L standards but use 0.8 g CHEMEON eTCP POWDER for
the 8 g/L standard and 0.4 g CHEMEON eTCP POWDER for the 4 g/L standard.
6. New standards should be made every two months. If they become cloudy or have precipitation
before then, discard and make new ones.
Procedure for Analyzing CHEMEON eTCP POWDER Bath Sample:
1. Allow the precipitate in a 50 – 100 mL sample of the CHEMEON bath to settle for several hours or
filter through fine porosity filter paper such as Whatman 40. Then filter through a 0.45 micron filter.
2. Turn on the spectrophotometer. Allow the lamp to warm up according to the manufacturer’s
specifications.
3. Set the wavelength of the spectrophotometer to 565 nm.
4. Fill the quartz cuvette with deionized water and wipe down the outside walls of the cuvette so they
are free of fingerprints, streaks, and moisture.
5. Place the cuvette in your spectrophotometer and “zero” the instrument according to manufacturer’s
specifications.
6. Measure the absorbance value of the deionized water according to the manufacturer’s
specifications. Record this value. It should be very close to zero.
7. Using a clean plastic pipette, refill the cuvette with one of your CHEMEON eTCP POWDER
standards, clean the walls of the cuvette again and then place it in your spectrophotometer.
8. Measure and record the absorbance value.
9. Repeat steps 4 through 8 for the other two standards and the filtered bath sample.
10. Plot the absorbance versus concentration for your standards on a graph and determine the equation
of the line. Microsoft Excel or a graphing calculator can be used for this plot.
11. Plug the absorbance of the bath sample into the equation to obtain the concentration.
Some spectrophotometers may require daily calibration; otherwise may require weekly calibration. Verify by
rerunning standards and checking consistency.
If you need assistance with this you can call the CHEMEON Technical Center and they will provide you with a Microsoft Excel spreadsheet that will calculate the concentration for you.
If you are interested in quotes for a spectrophotometer or other related equipment, you can contact Chemetall or CHEMEON.
EQUIPMENT
The Chemetall Chemical Metering Pump can be used to automatically replenish this product. Please contact the Chemetall Process Equipment and Engineering Department for specific recommendations.
NOTES ON USE(See Safety Data Sheet)
Tanks and spray washers should be constructed of virgin, welded polypropylene, alloy 316 stainless steel, or lined with Koroseal or Teflon. Before initial charge, thoroughly clean the tank. For new tanks or liners, rinse surfaces with the acid chemistry of choice for lowering pH, then rinse thoroughly with water. Pumps
and valves should be constructed of stainless steel, preferably type 316L. Suitable plastics such as PP or CPVC may be used for piping and nozzles. Heating surfaces should be Teflon-coated. As with any chemical, the materials described in this document must be used within the recommended operating ranges
for these equipment recommendations to apply.
Avoid contact with or mixing with chlorine-releasing materials.
SAFETY AND HANDLING
Prior to handling and use of any of the materials referenced in this document, the Safety Data Sheets should be read and understood by all personnel in contact with these materials.
KEEP OUT OF REACH OF CHILDREN STORAGE
Dry indoor storage at temperatures between 40 °F and 100 °F (4.4 °C and 37.8 °C) is recommended, away from any incompatible materials referenced in the Safety Data Sheets. All containers should be tightly closed when not in use.