1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions Rev 03 2012 12 06 N Status / Revised Removed A4, A2 to N Status replaced by WSS-M21P51-A2 G. Weber, NA 2004 09 14 Revised Para 3.5.1 revised D. Drobnich 2004 09 08 Revised Para 1, 3.3.1, 3.3.2, 3.3.4, 3.4.1, 3.4.3, 3.5.1, 3.5.2, 3.5.3, 3.5.4,
2、 3.5.5, 3.7.1, 3.12, Table 1 and Table 1 (C) revised D. Drobnich 2004 09 02 Activated D. Drobnich Controlled document at www.MATS Copyright 2012, Ford Global Technologies, LLC Page 1 of 6 CORROSION PROTECTIVE COATING, ZINC NICKEL ALLOY, WSS-M21P44-A1 TRIVALENT PASSIVATE, SILVER CORROSION PROTECTIVE
3、COATING, ZINC NICKEL ALLOY, WSS-M21P44-A2 TRIVALENT PASSIVATE WITH ORGANIC SEAL, SILVER NOT TO BE USED FOR NEW DESIGN CORROSION PROTECTIVE COATING, ZINC NICKEL ALLOY, WSS-M21P44-A3 TRIVALENT PASSIVATE WITH CATHODIC ELECTROCOAT, BLACK 1. SCOPE The materials defined by these specifications are corrosi
4、on protective coatings applied sequentially per supplier specifications over steel. They consist of an alkaline zinc nickel alloy electrodeposit and a trivalent chromium passivate/adhesion promoter. A2 and A3 are followed respectively by an organic seal, a cathodic electrocoat, or a waterborne top c
5、oat. When used with an integrally cured torque modified post dip, these processes provide consistent torque-tension control. All processes are free of hexavalent chromium, lead and cadmium. 2. APPLICATION These specifications were released for materials used as corrosion protective coatings over ste
6、el fasteners and small parts. The processes may induce hydrogen embrittlement and therefore these coatings must be hydrogen embrittlement relieved when applied to high hardness parts in accordance with WSS-M99A3-A. The cure temperature of the organic seal used for A2 is 80 to 120 C. The cure tempera
7、ture of the cathodic system for A3 is 175 to 200 C. These coatings shall not be specified if this temperature adversely affects the component being coated. 2.1 SERVICE TEMPERATURE The maximum continuous service temperature for A and A2 is 310 C. The maximum continuous service temperature for A3 is 2
8、60 C. ENGINEERING MATERIAL SPECIFICATION WSS-M21P44-A1/A4 Copyright 2012, Ford Global Technologies, LLC Page 2 of 6 3. REQUIREMENTS 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Quality System Requirements for Production Materia
9、ls (WSS-M99P1111-A). Part producers must use approved materials specified on the Companys Approved Source List. 3.2 APPROVED APPLICATOR QUALITY REQUIREMENTS Applicators must follow coating manufacturer procedures and recommendations for chemical usage, equipment, analysis and processing. 3.3 APPEARA
10、NCE 3.3.1 The ZnNi coating will have a metallic silver appearance prior to passivate/adhesion promoter application. 3.3.2 The passivate/adhesion promoter will have an appearance of slight iridescence and color variation consistent with interference films (e.g. yellow, orange, green, blue, purple var
11、iegation). 3.3.3 The organic seal used for A2 will be a translucent film free from discontinuities. 3.3.4 The cathodic coating used for A3 will be a semi-gloss black finish free from discontinuities. The gloss level for A3 shall be 25 to 55 of gloss when measured using a 60 meter. 3.4 COATING COMPOS
12、ITION 3.4.1 The alkaline ZnNi electrodeposit shall have a nickel content of 12 to 15% as measured by calibrated X-ray fluorescence spectrometers in accordance with the suppliers requirements. In some instances a strike layer may be applied to the substrate prior to ZnNi electrodeposition. In such ca
13、ses the presence of a strike layer must be noted so that appropriate methods for measuring composition and thickness of the ZnNi may be employed. 3.4.2 The alkaline ZnNi electrodeposit shall have a phase composition which includes substantial metallurgical gamma phase ZnNi as defined by standard ref
14、erence phase diagrams such as ASM Handbook, Volume 3, 10thedition. Presence of substantial gamma phase ZnNi may be demonstrated by comparing x-ray diffraction patterns to reference materials such as ICDD PDF 06-0653. Crystallographic preferred orientations, such as 330 and/or 600 Miller index hkl fo
15、r gamma phase ZnNi, should be present in accordance with the chemical suppliers requirements; and subject to periodic verification using x-ray diffraction or an alternative, preapproved, standard crystallographic determination method. 3.4.3 The passivate/adhesion promoter shall have a composition in
16、 accordance with the chemical suppliers requirements. For A3, the passivate/adhesion promoter must be cobalt and carboxylic acid free. 3.4.4 The organic seal of A2 and the cathodic coating of A3 shall have a composition in accordance with the chemical suppliers requirements. ENGINEERING MATERIAL SPE
17、CIFICATION WSS-M21P44-A1/A4 Copyright 2012, Ford Global Technologies, LLC Page 3 of 6 3.5 COATING THICKNESS 3.5.1 The ZnNi electrodeposit will have an optimum thickness of 8 + 4/- 2 microns measured on flat surfaces. Documentation demonstrating throwing power, measured in accordance with suppliers i
18、nstructions, in excess of 70% will assure adequate thickness in recessed areas including threads. 3.5.2 The passivate/adhesion promoter thickness is not subject to measurement but will be less than one micron and greater than 50 nm based upon SEM examinations using cryofractured samples and/or calib
19、rated depth profiling using scanning Auger or x-ray photoelectron spectroscopies. 3.5.3 The organic seal thickness for A2 is typically between 0.5 and 5 microns. The minimum thickness shall be sufficient to meet the corrosion requirements of the substrate material. A typical film that exhibits the a
20、ppropriate corrosion resistance for A2 is 1 to 2 microns in thickness. 3.5.4 A specific cathodic coating thickness for A3 is not specified. The minimum thickness shall be sufficient to meet the corrosion requirements of the substrate material. A typical film that exhibits the appropriate corrosion r
21、esistance for A3 is 12.7 to 20.0 microns in thickness. 3.5.6 Excessive coating thickness on threaded components may cause assembly concerns. The general requirements of the Ford Worldwide Fastener Standards, Finish Specification WX100, and Section 5 apply to these coatings. 3.6 THREAD ACCEPTANCE REQ
22、UIREMENTS (WA900, WE900, WX100) For thread acceptance requirements see Ford Worldwide Fastener Standards WA900, WE900 and WX100. 3.7 CURING AND TRANSPORTATION 3.7.1 The ZnNi electrodeposit with passivate/adhesion promoter will be cured and packaged in accordance with suppliers requirements prior to
23、transportation to a subsequent coating applicator. 3.7.2 The organic seal coating for A2 shall be cured 15 minutes at a metal temperature of 80 to 120 C. 3.7.3 The cathodic electrocoat for A3 shall be cured 20 minutes at a metal temperature of 175 to 200 C. 3.7.5 These coatings shall not be used on
24、materials that are adversely affected by these metal temperatures. ENGINEERING MATERIAL SPECIFICATION WSS-M21P44-A1/A4 Copyright 2012, Ford Global Technologies, LLC Page 4 of 6 3.8 CLEANING Prior to coating, the substrate shall be free of oil, dirt, and similar foreign materials. If a cleaning proce
25、ss is necessary, it shall have no detrimental effect on the substrate, including freedom from embrittlement. 3.9 ADHESION The coating shall withstand normal handling, storage, and installation without flaking or peeling or other loss of adhesion. 3.10 TORQUE TENSION (WZ101) Applicators preparing the
26、 final layer of parts in accordance with A2, A3 or A4 must have torque tension measurement equipment in accordance with WZ 101. The coatings shall meet the torque and friction coefficient specified in Table 1. 3.11 RESISTANCE PROPERTIES 3.11.1 Corrosion resistance (SAE/USCAR-1, ASTM B 117, ASTM D 61
27、0, WX100) Fasteners shall be tested and evaluated in accordance with SAE/USCAR-1, and shall pass the number of hours specified in Table 1 and the “General Requirements” of WX100. Parts other than fasteners shall be tested in accordance with ASTM B 117. Parts shall show no single ferrous corrosion sp
28、ot larger than 1.5 mm in diameter, and shall not exhibit ferrous corrosion overall exceeding 0.1%, per ASTM D 610, grade 8, after the number of test hours specified in Table 1. 3.11.2 Water Resistance (FLTM Bl 104-01) Shall not blister or show any signs of red rust when subjected to immersion in wat
29、er for 240 hours. 3.11.3 Gasoline Resistance Shall not blister or show any signs of softening or dulling when subjected to immersion in current factory fill gasoline for 24 hours at 23 +/- 2 C. 3.11.4 Hot Oil Resistance Shall not blister or show any signs of softening or dulling when subjected to im
30、mersion in engine oil (SAE 10W30 per WSE-M2C903-A2 or equivalent) for 24 hours at 66 +/- 3 C. ENGINEERING MATERIAL SPECIFICATION WSS-M21P44-A1/A4 Copyright 2012, Ford Global Technologies, LLC Page 5 of 6 3.11.5 Ethylene Glycol Resistance Shall not blister or show any signs of softening or dulling wh
31、en subjected to immersion in a 50% solution of water and long life coolant concentrate (WSE-M97B44-B or equivalent) for 24 hours at 23 +/-2 C. 3.11.6 Brake Fluid Resistance Shall not blister or show any signs of softening or dulling when subjected to immersion in currently approved brake fluid for 2
32、4 hours at 23 +/-2 C. 3.11.7 Power Steering/Transmission Fluid Shall not blister or show any signs of softening or dulling when subjected to immersion in current factory fill power steering and transmission fluid for 24 hours at 66 +/-3 C. 3.12 ELECTRICAL CONDUCTIVITY Coating system A exhibits elect
33、rical continuity to the substrate but not sufficient enough to be considered acceptable for general for electrical grounding applications. Coating systems A2, A3 and A4 are not recommended for electrical grounding applications. 3.13 FORMABILITY For A and A2, parts such as brackets, stampings, tubing
34、, etc. that will be post formed following processing shall follow coating manufacturers approved procedures; such as, ISO 8401-1986 (E) - cylindrical mandrel bending ensuring bendability, must be used and results recorded. 3.14 ULTRAVIOLET EXPOSURE (ASTM D 4587-01, ASTM G 154-00a) A and A2 coating s
35、ystems are recommended for applications using ASTM D4587-01. A3 coating system is recommended for applications using ASTM G154-00a. ENGINEERING MATERIAL SPECIFICATION WSS-M21P44-A1/A4 Copyright 2012, Ford Global Technologies, LLC Page 6 of 6 TABLE 1 GUIDANCE TO PROPERTIES OF WSS-M21P44-A/A4 COATING
36、SYSTEMS Specification Color Typical Thickness m WZ 101 Torque NM (a) WZ 101 Friction Coefficient N.S.S. Hours Ferrous Corrosion N.S.S. Hours Zinc Oxidation (b) Min. Cycles APGE to Red Rust (c) Examples of Part Applications WSS-M21P44-A Silver 6 to 12 NA NA 480 hours NA 15/30 Parts for interior and e
37、xterior use especially where good corrosion protection and electrical conductivity are required, brackets, clips, stampings and tubing. WSS-M21P44-A2 Silver 7 to 14 Mean: 44-49 3 Sigma: 38-55 Mean: .14 +/- .01 3 Sigma: .14 +/- .03 960 hours 360 hours 20/40 Parts for interior and exterior use where v
38、ery good corrosion protection is required, externally threaded fasteners M4.2 and larger, brackets, clips, stampings and tubing. WSS-M21P44-A3 Black 18 to 30 Mean: 44-49 3 Sigma: 38-55 Mean: .14 +/- .01 3 Sigma: .14 +/- .03 960 hours 480 hours 30/60 Parts for interior and exterior use where excellen
39、t corrosion protection is required, externally threaded fasteners M4.2 and larger, brackets and stampings. (a) Based on WZ101 test program B for M10x1.5 PC 8.8 surrogate bolt. Torque values taken 25.3 kN tension. (b) It is a characteristic of ZnNi that it will produce thin and adherent layers of zin
40、c oxide corrosion products, often referred to as gray veil, as it slowly sacrifices itself. Visible and voluminous zinc oxidation is characterized as corrosion products, induced by a neutral salt spray cabinet, which are clearly visible when wet and have affected surface topography on non-post forme
41、d surfaces and fasteners in accordance with SAE/USCAR-1 section 5. (c) Based upon Fasteners installed into test panels and testing in accordance with FLTM BI 123-02. Test results are for comparative purposes only and do not necessarily correlate to actual APG performance. The number left of the slant line indicates the APGE performance when tested against cathodic electrocoated cold rolled steel panels. The number right of the slant line indicates the APGE performance when tested against primed, painted and clearcoated 6111-T4 aluminum panels.
