Protection upgraded SurTec 881 Trivalent Decorative Chromium Process (Anti Salts Type) Properties environmentally friendly, hexavalent chromium free plating process high corrosion protection against calcium chloride together with good CASS properties trivalent chromium plating finish with very attractive light white colour very easy and stable plating with TCP anodes which are specially designed for trivalent chromium processes colour measurement (Konica Minolta d 700): L = 80.0-84.0 / a = 0.0-0.4 / b = 1.5-2.0 IMDS-number: 560353453 Application The process SurTec 881 includes the following products: SurTec 881 S Conductivity Salts SurTec 881 I Chromium Solution SurTec 881 II Maintenance Additive SurTec 881 M Make-Up Solution SurTec 880 W Wetting Agent SurTec 880 ET LCD Booster make-up values: SurTec 881 S Conductivity Salts 220 g/l SurTec 881 I Chromium Solution 250 ml/l SurTec 881 M Make-Up Solution 12 ml/l (10-14 ml/l) SurTec 880 W Wetting Agent 1.5 ml/l (1.0-3.0 ml/l) SurTec 880 ET LCD Booster 1 ml/l analytical values: chromium (III) 17 g/l (15-19 g/l) SurTec 881 S Conductivity Salts 220 g/l (220-280 g/l) SurTec 881 M Make-Up Solution 12 ml/l (10-14 ml/l) SurTec 880 W Wetting Agent required if surface tension > 40 mn/m page 1
make-up: Steps for make-up: 1. Fill approx. 60 % deionised water into the tank. 2. Heat up to 55-60 C. 3. Add the desired amount of SurTec 881 S under vigorous agitation. (It is very important to resolve the salts completely before moving to the next step!) 4. Add the required volume of SurTec 881 I. 5. Mix thoroughly and heat up to working temperature (60 C). 6. Gradually adjust the ph-value (very slowly!) to ph 3.2 with 25 % sodium hydroxide solution under vigorous agitation (the ph-value is very important so control the ph accurately!). 7. Leave the solution at this temperature for at least 12 hours. 8. Add the required amounts of SurTec 881 M, SurTec 880 W and SurTec 880 ET under vigorous agitation. 9. Install the anode system. 10. Fill up to the final volume with deionised water. 11. Adjust the ph-value to ph 3.2 again. 12. Electrolyse with freshly nickel-plated steel cathodes for 1 Ah/l before production. Change cathodes every 30 minutes. 13. Control the ph during this initial working step and correct any drop in ph with 25 % sodium hydroxide solution. The ph-value will stabilize itself after a few days. temperature: 60 C (55-60 C) ph-value: 3.2 (3.0-3.4) adjust with sodium hydroxide solution (25 %) resp. with sulfuric acid (10 %) A local high ph condition is harmful; therefore make all additions very slowly under vigorous agitation. Never allow the ph to rise above ph 4.0 to avoid a loss of efficiency. plating time: 5 min (3-8 min) current density: 8 A/dm 2 (6-12 A/dm 2 ) anodic current density: 6 A/dm 2 (5-7 A/dm 2 ) cell voltage: anodes: 8-12 V specially designed TCP anodes (Trivalent Chromium Plating); incorrect anodes will lead to an irreversible breakdown of complexors Handle the anodes with care to prevent any chipping or cracking of the coating (anode current density < 7 A/dm 2 ). agitation: mild air agitation (with twin-row PVC or ABS air agitation pipes) and/or gentle bath movement necessary Rack movement is highly recommended, especially for large tanks containing more than 800 litre of plating solution. page 2
tank material: tanks lined with PVC or PP Clean new plastic-lined tanks and pipework thoroughly by filling with diluted sulfuric acid solution before use. filtration: heating: exhaust: hints: recommended: continuous filtration; carbon filtration is necessary to remove organic contaminations required: titanium coils or titanium-clad or silica cased electric immersion heater (thermostatic control is essential) required for worker s protection: local exhaust ventilation is essential, good general ventilation is recommended After a prolonged shut-down period, heat up the SurTec 881 bath to working temperature 2-3 days before re-start to ensure that all precipitates are completely re-dissolved. Analyse the composition of the solution and the ph-value and adjust it, if necessary. Then electrolyse (at normal current density) for 30 min to 1 h using freshly nickel-plated cathodes before re-start the production. Change the freshly nickel-plated cathodes every 30 minutes of electrolysis. recommended process sequence: 1. Bright Nickel Process, e.g. SurTec 856 2. rinse 3. Decorative Chromium Process SurTec 881 4. rinse 5. passivation SurTec 881 does not passivate the plated chromium surface as well as a hexavalent chromium solution. Therefore in most cases a subsequent passivation e.g. with SurTec 880 B Chrome Passivation (chromium-free) is advisable. 6. rinse 7. hot deionised water rinse 8. drying Between each step, there has to be rinsed with clean running water. The rinsing methods have to be adapted to the plating line. After the Bright Nickel Process prior to the Decorative Chromium Process SurTec 881 an efficient rinsing with clean running water is very important. Technical Specification (at 20 C) Appearance Density (g/ml) ph-value (conc.) SurTec 881 S powder, white ca. 1.221 kg/l ca. 5.8 (at 1 %) SurTec 881 I liquid, dark purple 1.331 (1.28-1.35) < 1 SurTec 881 II liquid, colourless-yellowish 1.023 (1.00-1.04) 12.3 (11-13.5) SurTec 881 M liquid, colourless 1.078 (1.00-1.20) 8.8 (7-11) to light yellow SurTec 880 W liquid, colourless 1.009 (0.97-1.04) 4.0 (3-5) SurTec 880 ET liquid, light blue-greenish 1.124 (1.10-1.15) 1.4 (1-2) page 3
Maintenance Check the ph-value regularly. Analyse the concentration of SurTec 881 S and chromium(iii) regularly and adjust it to the standard range. Analysis methods are separately available on request. For optimum performance of the process, an auto-dosing system of SurTec 881 I and SurTec 881 II according to Ampere-hours is strongly recommended. Do NOT pre-mix the additives before adding to the plating solution. During the normal plating process the surface tension of the solution will increase. When the surface tension rises above 40 mn/m, typically an addition of 0.5-1.0 ml/l SurTec 880 W Wetting Agent is required. Although SurTec 881 solution is tolerant to impurities, a good rinsing is essential after the Bright Nickel Process prior to the Decorative Chromium Process SurTec 881, especially when tubular or difficult to drain components are being processed. Inefficient rinsing will cause nickel contaminations which may lead to a loss of efficiency. Hull Cell Test Perform all tests in a standard 250 ml Hull cell: Heat the bath sample up to 60 C, adjust the ph-value under stirring to ph 3.2 with sodium hydroxide solution (25 %) resp. with. sulfuric acid (10 %), and pour it into the Hull cell. Nickel-plate a well-prepared brass panel with SurTec 856 and insert the panel into the Hull Cell, move it there for 10-15 s without current. Then electroplate it with SurTec 881 at 4 A for 5 min at 60 C without agitation. Use the specially designed TCP anode also in the Hull cell. Rinse the panel with water and dry it with hot or compressed air. An ideal panel has a distribution of 75-80 %. Test all additions in the Hull cell first before adding to the bath. Ingredients SurTec 881 S Conductivity Salts boric acid Consumption The consumption depends heavily on the drag-out. To determine the exact amounts of drag-out, see SurTec Technical Letter 11. The following values per 10,000 Ah can be taken as estimated average consumption: SurTec 881 I Chromium Solution 10-15 l* SurTec 881 II Maintenance Additive 10-15 l *Note: SurTec 881 I is a chromium containing additive and the addition rate should be adjusted for each actual installation by analysis. Small volumes of frequent replenishments (100-150 ml per 100 Ah) are strongly recommended to ensure constant plating properties. page 4
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: http://www.surtec.com 20 October 2016/DK, MT page 5