Metal Finishing Guide Book


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Table III. Automotive Standards 8-9 μm of Zinc Plate with Hexavalent Chrome-Free Passivation and Sealer (NSS Test Requirements per ASTM B 117) Auto Maker Hrs—White Corrosion Hrs—Red Corrosion GM 3044 Clear/Blue/Black Yellow-Iridescent 120 120 240 360 Ford WSS-M12P17B1/B3 Clear/Silver white Clear/Silver white 96 72 384 360 Heat Treatment Required Conditions May be specified Daimler Chrysler PS 1207 - R Iridescent—Rack Iridescent—Barrel Irridescent—Rack No sealer Iridescent—Barrel No sealer 150OC/1 hr 150OC/1 hr No Yes 120OC/4 hrs May be specified 200 160 120 100 As of Aug. 2001 (Subject to change). TYPICAL PROCESS SEQUENCE 1. Zinc or zinc alloy plate 2. Rinse 3. Activate (dilute acid) 4. Trivalent chrome passivate 5. Drag out rinse (optional) 6. Rinse (counter-current flow) 7. Dry (optional or as recommended) 8. Seal and/or topcoat 9. Dry PROCESS CONTROL Trivalent chromate conversion coatings are applied over acid or alkaline electroplated zinc and zinc alloys in conventional plating lines replacing existing hexava- Fig. 6. Cr(3) passivation surpasses requirements for Ford. 443

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