MIL-STD-868-SUP Nickel Plating, Low Embrittlement, Electro-DepositionThis standard covers the process and materials required for the electro-deposition of nickel on high strength steel substrates. Electro-deposited nickel is used for wear resistance, heat resistance, and as an undercoat for precious metals. Subsequent heat treating techniques needed to insure low hydrogen embrittlement of steel are also described. This standard meets the performance requirements of SAE-AMS- QQ-N-290 and may be used when SAE-AMS-QQ-N-290 is specified provided any unique requirements of SAE-AMS-QQ-N-290 are complied with.

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MIL-STD-868B

5.1.5   Masking.   Sections or areas of a part that are not to be plated shall be masked off.  Plug and masking materials that do not contaminate the plating solution shall be used.  Masking shall be performed at the most convenient step prior to plating.

5.1.6   Racking.  Sufficient contact area and pressure shall be provided to carry the current without overheating.  Racking should be performed at the most convenient step prior to plating.

5.2   Plating procedure.  The preferred method of cleaning is by dry blasting (Method I).  Other methods, such as Method 2, that can be demonstrated to be non-embrittling (paragraph 5.7) can be used with the approval of the procuring activity.

5.3   Method I.  The nickel plating procedure shall be as described below:

5.3.1   Step 1.  Parts shall be degreased as necessary.

5.3.2   Step 2.  Parts shall be dry blasted using 80 - 320 grit aluminum (AI2 03), silicon dioxide (Si02) or garnet per MIL-STD-1504.  Elapsed time between completion of cleaning and the next step shall not exceed sixty (60) minutes.

5.3.3   Step 3.   Rinse parts in cold water (optional).

5.3.4   Step 4.   Nickel plate at 3.2 to 5.4 A/dm2  (30 to 50 A/ft2) to the required thickness.  Nickel plate in either of the following solutions:

a.   Solution 1.

Nickel Sulfate                                     300 - 360 g/l (40 - 48 oz/gal) Nickel Chloride                                   30 - 60 g/l (4 - 8 oz/gal)

Boric Acid                                           30 - 45 g/l (4 - 6 oz/gal)

pH                                                      1.5 - 4.5

Temperature                                      46 - 60°C (115 - 140°F)

b.   Solution 2.

Nickel Sulfamate                                327 g/l (43.6 oz/gal) Make up Nickel Metal                                       69 - 90 g/l (9.2 - 12 oz/gal) Boric Acid                                           22.5 - 49 g/l (3 - 6.5 oz/gal)

NOTE:  The boric acid concentration should be maintained at or near saturation.  At

120° - 140°F saturation is approximately 6.0 - 6.5 oz/gal. pH        3 - 5

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