1、 ENGINEERING MATERIAL SPECIFICATIONDate Action Revisions 2006 02 20 Activated A. Cockman, D Nymberg Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 1 of 5 CORROSION PROTECTIVE COATING, ZINC NICKEL ALLOY, WSS-M21P25-B1 CHROMIUM-FREE PASSIVATE, U.V. RESISTANT BLACK S
2、EALER 1. SCOPE The materials defined by this specification provide a corrosion protective coating applied over steel. The materials consist of an alkaline zinc nickel alloy electro-deposit, followed by a chromium-free passivate, with the addition of a water soluble organic sealer designed to provide
3、 consistent torque-tension control and impart other desirable properties (i.e. additional corrosion protection, ultra violet protection, etc.). The finish is free of chromium, lead, and cadmium. 2. APPLICATION This specification was originally released to define the performance and appearance requir
4、ements for a chromium-free, alkaline zinc/nickel alloy coating on fasteners. The finish may also be suitable for other steel components, but requires testing appropriate for the part. The application processes may induce hydrogen embrittlement; therefore, this coating system must be hydrogen embritt
5、lement relieved when applied to high hardness parts in accordance with WSS-M99A3-A. The water soluble organic sealer must be baked at a peak metal temperature of 190 C for a minimum of 10 minutes to ensure the sealer is cured. Therefore, this finish shall not be specified if the cure temperature adv
6、ersely affects the component being coated. 2.1 SERVICE TEMPERATURE The maximum continuous service temperature for the finished part is 275 C. 3. REQUIREMENTS Material specification requirements are to be used for initial qualification of materials. 3.1 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS
7、Material suppliers and part producers must conform to the Companys Standard Requirements for Production Materials (WSS-M99P1111-A). Finished parts must comply with Ford Motor Companys restricted substances standard, WSS-M99P9999-A1. Part producers must use approved materials specified on the Company
8、s Approved Source List. 3.2 APPROVED APPLICATOR QUALITY REQUIREMENTS Applicators must follow coating manufacturer procedures and recommendations for chemical usage, equipment, analysis, and processing. Applicators must have documentation to show that procedures and recommendations are being followed
9、. ENGINEERING MATERIAL SPECIFICATIONWSS-M21P25-B1 Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 2 of 5 3.3 APPEARANCE (ASTM D 523) The coating shall be a uniform black color and shall be free from discontinuities when viewed without magnification. The finish shal
10、l exhibit a gloss of 4 or higher when measured with a 20 gloss meter per ASTM D523, shall not fill recesses and/or threads, or interfere with normal installation procedures. 3.4 COATING COMPOSITION The alkaline ZnNi electro-deposit shall have a nickel content of 12 to 15% as measured by calibrated X
11、-ray fluorescence spectrometers in accordance with the suppliers requirements. The plating shall be a uniform, homogeneous alloy of zinc and nickel throughout the thickness of the deposition and across the high and low current densities of the part. To ensure proper integrity, uniformity, adhesion,
12、and corrosion resistance, “strikes” are not permitted. Zinc/nickel is to be the only deposit applied directly to the base metal. The ZnNi plating, passivate, and water soluble organic sealer shall all have compositions in accordance with the chemical suppliers requirements. 3.5 COATING THICKNESS 3.5
13、.1 The ZnNi electro-deposit will have an optimum thickness of 8 +/- 3 microns measured on flat significant surfaces in accordance with ISO 4042 clause 10. Documentation demonstrating throwing power, measured in accordance with suppliers instructions, in excess of 70% will generally provide adequate
14、thickness in recessed areas, including threads. The ZnNi thickness shall not exceed 24 microns. 3.5.2 The hexavalent chromium-free passivate thickness is not subject to measurement. 3.5.3 The water soluble organic sealer thickness shall be 2 +/- 1 micron. The weathering resistance and torque tension
15、 characteristics imparted by the sealer shall meet the requirements of WZ101 and SAE J1960, across the entire range of thicknesses for each layer (ZnNi, passivate, and sealer), including all layers at minimum and all layers at maximum thickness (see Table1). 3.5.4 The corrosion resistance of the fin
16、ished part shall meet the number of cycles required by this specification across the entire range of thicknesses for each layer (ZnNi, passivate, and sealer), including all layers at minimum and all layers at maximum thickness (see Table1). 3.5.5 Fasteners with retained washers shall show no evidenc
17、e of excessive sticking of screw/washer and nut/washer assemblies. Parts shall meet the washer adhesion requirements outlined in WX100. 3.5.6 Excessive coating thickness on threaded components may cause assembly concerns. The general requirements of the Ford Worldwide Fastener Standards, Finish Spec
18、ification WX100, and Section 5 apply to this finish. 3.6 THREAD ACCEPTANCE REQUIREMENTS (WA900, WE900, WX100) For thread acceptance requirements see Ford Worldwide Fastener Standards WA900, WE900 and WX100. ENGINEERING MATERIAL SPECIFICATIONWSS-M21P25-B1 Printed copies are uncontrolled Copyright 200
19、6, Ford Global Technologies, LLC Page 3 of 5 3.7 CURING The water soluble organic sealer shall be cured at a peak metal temperature of 190 C for a minimum of 10 minutes. This coating shall not be used on materials that are adversely affected by these metal temperatures. 3.8 CLEANING Prior to coating
20、, the substrate shall be free of oil, dirt, and similar foreign materials. If a cleaning process 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 flaki
21、ng or peeling or other loss of adhesion. 3.10 TORQUE TENSION (WZ101) Applicators of threaded fasteners must have torque tension measurement equipment in accordance with WZ101. The coatings shall meet the torque and friction coefficient specified in Table 1. 3.11 RESISTANCE PROPERTIES 3.11.1 Cyclic C
22、orrosion Testing: (FLTM BI 123-01) Components shall be free of non-ferrous, white corrosion (equivalent to ASTM D 610 rating 6 or better) after 25 cycles. Components shall be free of ferrous, red corrosion (equivalent to ASTM D 610 rating 6 or better) after 40 cycles 3.11.2 Water Resistance (FLTM Bl
23、 104-01) Shall not blister or show any signs of red rust when subjected to immersion in water 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
24、Resistance Shall not blister or show any signs of softening or dulling when subjected to immersion in engine oil (SAE 10W30 per WSE-M2C903-A2 or equivalent) for 24 hours at 66 +/- 3 C. ENGINEERING MATERIAL SPECIFICATIONWSS-M21P25-B1 Printed copies are uncontrolled Copyright 2006, Ford Global Technol
25、ogies, LLC Page 4 of 5 3.11.5 Ethylene Glycol Resistance Shall not blister or show any signs of softening or dulling when subjected to immersion in a 50% solution of water and long life coolant concentrate (WSS-M97B51-A1 or equivalent) for 24 hours at 23 +/-2 C. 3.11.6 Brake Fluid Resistance Shall n
26、ot blister or show any signs of softening or dulling when subjected to immersion in currently approved brake fluid for 24 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
27、 steering and transmission fluid for 24 hours at 66 +/-3 C. 3.12 TABLE 1 GUIDANCE TO PROPERTIES OF WSS-M21P25-B1 Specification Color Typical Thickness (m) WZ101 Torque Nm (a) WZ101 Friction Coefficient Minimum Cycles APGE to White/Red Corrosion (b)(c) Examples of Part Applications WSS-M21P25-B1 Blac
28、k Zn/Ni Layer 6 to 14 typical 5 Min. 24 Max. Passivate Not measurable Sealer 1 Minimum 2 to 3 typical Mean: 44-49 3 Sigma: 38-55 Mean: 0.14 +/- 0.01 3 Sigma: 0.14 +/- 0.03 25/40 Parts for interior and exterior use where very good corrosion protection is required, externally threaded fasteners M4.2 a
29、nd larger, brackets, clips, 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 characteristic of ZnNi to produce thin and adherent layers of zinc oxide corrosion products, often referred to as gray veil, as it slowly sac
30、rifices itself (corrodes). 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 formed surfaces and fasteners in accordance with SAE/USCAR-1 section 5
31、. (c) Based on M10x35 PC 10.9 fasteners installed into phosphated, electrocoated, cold rolled steel panels and tested in accordance with FLTM BI 123-02. Test results are for comparative purposes only and do not necessarily correlate to actual APG or field performance. The onset of corrosion will occ
32、ur sooner, that is, at a lower number of APGE cycles, if the finish is damaged due to material handling. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of this specification. Salt spray testing is intended for monitoring th
33、e application process. ENGINEERING MATERIAL SPECIFICATIONWSS-M21P25-B1 Printed copies are uncontrolled Copyright 2006, Ford Global Technologies, LLC Page 5 of 5 4.1 CORROSION RESISTANCE (SAE/USCAR-1) Coated components tested in accordance with SAE/USCAR-1 and evaluated in accordance with ASTM D 610,
34、 Grade 6, typically pass 240 hours non-ferrous white corrosion and 720 hours ferrous corrosion. 4.2 Accelerated Weathering (SAE J1960, 0.55W/m2Irradiance 1000 Hours Borosilicate inner and outer filters, ASTM D 523) Prior to approval of new surface finishes Accelerated Weathering tests will be conduc
35、ted on test panels and/or test fasteners, variation in testing and testing protocol may be necessary to evaluate the new finish. Parts shall not exhibit any peeling, cracking, blistering, loss of adhesion, or reduced corrosion protection after accelerated weathering. Color change shall be a minimum of rating 4 when evaluated to AATCC Evaluation procedure 1, ISO 105-A02. Gloss Change shall be a maximum of 25%, (60 gloss meter per ASTM D 523). “X“ scribe tape pull adhesion, minimum retention 90%
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