SurTec 650 chromital TCP

Transcription

1 Protection upgraded SurTec 650 chromital TCP Pre-Treatment for Aluminium prior to Coating Properties hexavalent chromium-free pre-treatment, suitable before painting, powder coating and gluing liquid concentrate based on trivalent chromium approved by GSB and Qualicoat excellent corrosion protection, comparable to hexavalent passivations best performance on extruded material and sheets easy to handle in immersion and spray application produces colourless passivation layers applied for US-patent: 6,375,726; 6,511,532; 6,521,029; 6,527,841 IMDS-number: Application SurTec 650 chromital can be used in immersion and spray application. For the make-up, dilute SurTec 650 chromital concentrate in deionised (DI-)water. The process includes the following products: SurTec 650 chromital is used for new make-up SurTec 650 B chromital is used for replenishment make-up value: for immersion and spray application SurTec %vol ( %vol) analytical value: zirconium 100 mg/l ( mg/l) Make-up: Steps during make-up: temperature: 25 C (20-35 C) 1. Pour SurTec 650 chromital into the tank and dilute with DI-water under vigorous stirring. 2. Control the ph-value and adjust it cautiously with 5 % sulfuric acid resp. with 1 % sodium hydroxide solution, if necessary. ph-value: 3.5 ( ) adjust with 5 % sulfuric acid resp. with 1 % sodium hydroxide solution page 1

2 application time: 1 min (0.5-3 min) spray pressure: 1 bar ( bar) agitation: tank material: rack material: filtration: heating: exhaust: necessary stainless steel, or steel with acid- and fluoride-resistant coating material: titanium, stainless steel (V4A), aluminium, plastic necessary; times the total bath volume per hour; pore size: 25 µm not necessary; constant temperature of C required required for worker s protection hints: Storage: During storage, a slight precipitation may occur inside the concentrates of SurTec 650 and SurTec 650 B, which will not impair quality or function of the products. Process sequence: Prior to the passivation with SurTec 650, the aluminium surface must be cleaned and deoxidised thoroughly. The surface must be water-break free. If using a silicate-containing degreasing, subsequently the surface has to be treated with a fluoride-containing deoxidising. In the last rinse prior to the SurTec 650 bath, a conductivity of max. 350 µs/cm is required in order to avoid variations in the following SurTec 650 chromital bath. After passivation with SurTec 650 chromital, the parts have to be rinsed. The conductivity of the final rinse must be below 30 µs/cm. Tests: As a qualitative determination of the deposited SurTec 650 layer a spot test is available. The test kit and its instruction can be ordered separately. Further treatment: The treated surfaces can be coated immediately after drying or stored, as long as they are protected from contamination and temperature extremes. For optimum results, the parts should be coated within 7 days. In order to be compliant with QUALICOAT, the coating should be applied within 16 hours, for GSB within 24 h, respectively as Premium Coater within 12 hours. Layer weight: For pre-treatment of extruded profiles before powder coating, a layer weight of g/m 2 must be adjusted. The formation of the passivation layer should be tested directly after the pre-treatment via spot test. Drying temperature: The drying temperature should be 65 C (room temperature up to 100 C). page 2

3 recommended process sequence: Standard process sequences for immersion application: 3 active steps: 1. weak alkaline cleaning e.g. SurTec acid pickling e.g. SurTec passivation with SurTec 650 chromital 4 active steps: 1. weak alkaline cleaning e.g. SurTec alkaline etching e.g. SurTec 406 AS 3. acid desmutting e.g. SurTec passivation with SurTec 650 chromital Standard process sequences for spray application: 2 active steps: 1. acid pickling e.g. SurTec passivation with SurTec 650 chromital 3 active steps: 1. alkaline cleaning e.g. SurTec 406 AS 2. acid pickling e.g. SurTec passivation with SurTec 650 chromital Between each step, there has to be rinsed. The rinsing methods have to be adapted to the plating line. These process sequences are general recommendations. To customise the process, modifications may be necessary. Technical Specification (at 20 C) Appearance Density (g/ml) ph-value (conc.) SurTec 650 liquid, green, clear-turbid, ( ) contingency precipitate SurTec 650 B liquid, green, clear-turbid, ( ) approx. 1.6 contingency precipitate hint: During the first days of storage, the ph-value of SurTec 650 increases slightly. Maintenance and Analysis Check the ph-value regularly. Analyse the concentration of zirconium regularly and adjust by adding SurTec 650 B. Sample Preparation Take a sample at a homogeneously mixed position and let it cool down to room temperature. If the sample is turbid, let the turbidity settle down and decant or filter the solution. page 3

4 Zirconium Analysis by Photometry equipment: Zirconium Cuvette Test LCK 364 of Co. HACH Table photometer or POCKET photometer with wave length 500 nm with adapter for HACH cuvette tests and POCKET light protection cap procedure: For all bathes with a make-up concentration > 2 %vol SurTec 650 a dilution is required. For bathes with 2-6 %vol SurTec 650 prepare a dilution of 1:4 (F = 4): 1. Pipette 25 ml filtered bath sample into a 100 ml volumetric flask, make up to the mark with deionised water and mix well. Measuring of the blind value: 2. Close the cuvette slit of the photometer and set the blank value at 500 nm against air. 3. Then remove the sealing from the DosiCap, unscrew the cap from the cuvette and screw the inverted cap on the cuvette. 4. Then let the dye stuff dissolve in the cuvette by shaking for 10 s (now the solution is yellow, it must be clear and free of air bubbles and particles). Clean the cuvette with a soft towel to remove fingerprint residues and measure the absorbance ABS (zero) in the photometer at 500 nm. Measuring of the bath sample: 5. Take the cuvette out of the photometer, open the cap and pipette 0.2 ml diluted bath sample into the cuvette. 6. Close the cuvette with the cap and shake it very well (depending on the zirconium content, the solution becomes slightly or strongly orange). 7. After 5 minutes measure the absorbance ABS (zero + sample) at 500 nm in the photometer. calculation: Determination with POCKET or table photometer at 500 nm (measuring without program): First calculate the 0.2 ml cuvette volume change for the determination of the blank value: ABS (zero) = ABS (corr.) With the corrected zero value calculate the absorbance of the sample: ABS (zero + sample) ABS (corr.) = ABS (sample) ABS (sample) = mg/l zirconium For dilutions multiply the calculated zirconium content with the dilution factor F (F = 4): mg/l zirconium F = mg/l zirconium in the bath correction: addition of 1 ml/l SurTec 650 B = rise by 4 mg/l zirconium page 4

5 SurTec 650 Determination of the Layer Weight equipment: analytical balance (+/- 0.1 mg) reagents: 50 %vol nitric acid (65 %) procedure: calculation: hint: 1. Passivate a test part with a known surface area in m 2 (preferably > 2 dm 2 ) in SurTec Rinse with deionised water and dry with compressed air at room temperature. 3. Weigh the dry part within 3 h after passivation with the analytical balance (= M 1 ). 4. Remove the passivation layer in nitric acid (4 min at C). 5. Rinse with deionised water and dry with compressed air at room temperature. 6. Weigh the dry part again with the analytical balance (= M 2 ). 7. Repeat the analysis with a cleaned and deoxidised but notpassivated test part(= M 3 and M 4 ) (M 1 - M 2 ) / surface area = A (M 3 - M 4 ) / surface area = B A - B = layer weight in g/m 2 For determination of the layer weight always a fresh solution should be used. At the latest after 1 m 2 /l the solution has to be renewed. SurTec Photometric Determination of the Zirconium Content in the Layer equipment: regents: preparation: procedure: extraction cell for 400 cm 2 sheet metals spectrophotometer with 500 nm wave length Zirconium Cuvette Test LCK 364 of Co. HACH aluminium sheet (size 100 mm x 200 mm = 0.04 m 2 surface) 0.2 mol/l HCl solution (pipette 20 ml 37 % hydrochloric acid into a 1 l measuring flask, make up to the mark with deionised water and mix well) Passivate the aluminium sheet (100 mm x 200 mm), subsequently dry it with compressed air. Stripping of the passivation layer: 1. Fill exactly 85 ml 0.2 mol/l HCl solution into the extraction cell. 2. Put the passivated aluminium sheet immediately (without storage) after the compressed air drying into the cell and there let it react for 10 minutes. Move the sheet from time to time to and fro. 3. Thereafter, remove the sheet and let it drop off for 10 seconds above the cell (make sure to catch all drops in the cell!). 4. Fill the extraction mixture from the cell into a beaker and mix with a glass rod. Photometric Analysis (with Zirconium Cuvette Test LCK 364): page 5

6 5. Unscrew the cap from the cuvette, pipette exactly 2 ml of the containing solution out of the cuvette and discard it. 6. Then remove the sealing from the DosiCap and pour the dyestuff into the cuvette. Wait until the air bubbles have disappeared. 7. Adjust the zero point of the photometer at 500 nm against air. 8. Measure the absorbance of the cuvette including the indicator in the photometer at 500 nm and note the measured value ABS (zero). 9. Remove the cuvette from the photometer, unscrew the cap of the cuvette and add exactly 3 ml extraction solution into the cuvette. 10. Close the cuvette with the cap, shake it well and wait for 5 min. 11. Measure the absorbance of the cuvette again in the photometer at 500 nm and note the measured value ABS (zero + sample). 12. Then calculate the concentration. calculation: Determination with POCKET or table photometer at 500 nm (measuring without program): First calculate the 3.0 ml cuvette volume change for the determination of the blank value: ABS (zero) = ABS (corr.) With the corrected zero value calculate the absorbance of the sample: ABS (zero + sample) ABS (corr.) = ABS (sample) With the absorbance of the sample it is possible to calculate the zirconium content of the layer in mg/m 2, by using the product specific factor: ABS (sample) = mg/m 2 zirconium desired value: mg/m 2 zirconium Ingredients chromium(iii) salts zirconium fluoride Consumption and Stock Keeping The consumption depends heavily on the drag-out. To determine the exact amounts of drag-out, see SurTec Technical Letter 11. The following values can be taken as estimated average consumption: 6-18 ml SurTec 650 concentrate are sufficient for treating 1 m 2 surface (including a supposed drag-out of 100 ml/m 2 ). The consumption is strongly dependent on further factors: the drag-out may be significantly higher for rough surfaces and scooping parts (up to 300 ml/m 2 ) page 6

7 at rough surfaces, the effective surface is higher than the part's dimension, so the chemical consumption is higher drag-in of alkalinity into the SurTec 650 bath can lead to precipitations which means additional consumption In order to prevent delays in the production process, per 1,000 l bath the following amounts should be kept in stock: SurTec 650 SurTec 650 B 50 kg 50 kg Product Safety and Ecology Classification and designation are noted in the Material Safety Data Sheets (according to the European legislation). The safety instructions and the instructions for environmental protection have to be followed in order to avoid hazards for people and environment. Please pay attention to the explicit details in our Material Safety Data Sheets. Warranty We are responsible for our products in the context of the valid legal regulations. The warranty exclusively accesses for the delivered state of a product. Warranties and claims for damages after the subsequent treatment of our products do not exist. For details please consider our general terms and conditions. Further Information and Contact If you have any questions concerning the process, please contact your local technical department. For further information and contact details please visit our homepage: 22 March 2017/DK, PV page 7