The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Cadmium plating over aluminum alloys with Electroless Nickel as Undercoat

Q. I looking to see if anyone knows what the thickness of cadmium with olive drab chromate over electroless nickel on aluminum are needed to pass 1000 hour salt spray. Any information provided will be very helpful.

Thank you,

Casey Stein
- Tempe, Arizona, US
2003

---

Q. I am working on a Design Project for the Aerospace Industry which demands that the product (made of die-cast aluminum) be plated with Olive drab Cadmium over suitable underplate and should withstand 1000 hours of salt spray and still exhibit no exposure of base metal evident to the unaided eye.

Can anyone suggest a plating method (the underplate, thickness of the underplate and thickness of Cadmium coating) which can withstand the above requirement?

Ranjith Thomas Cyriac
SOURIAU INDIA - Cochin
2006

---

---

---

Multiple threads merged: please forgive chronology errors and repetition  🙂

---

---

Q. Hi,

My customer wants the components which can withstand 1000 hrs salt spray. The base metal is Aluminium. There are two issues here:

1. Whether cadmium plating with electroless nickel as undercoat can withstand 1000 hrs salt spray?

2. If not, what is the best plating with olive green finish to withstand 1000 hrs salt spray?

C.N.RAMESH
- Bangalore, KARNATAKA, INDIA
2006

---

---

Q. We have been using anodized MIL-DTL-16232 [from DLA] electrical connectors, but there is a problem with long lead times. We have looked at other suppliers, but they do not have the insert configurations that we need, nor do they offer the anodized finish.

The standard finish is olive drab zinc chromate primer ⇦ this on Amazon (affil link)] over cadmium plating on an aluminum body. In our environment, the connectors can be exposed to salt spray, calcium chloride, hydrochloric acid fumes and wash down with a high-pressure washer. We have found the cadmium plating to be poor protection. Other options include electroless nickel, olive drab cadmium over nickel, olive drab zinc cobalt, non-conductive black zinc cobalt and conductive black zinc cobalt. We have been told all of these finishes are worse than the cadmium plating and like the anodized parts, they are long lead-time.

So we hope that we may be able to find a spray on coating to apply to the standard cadmium plated part to protect it. Does anyone have suggestions?

Thanks,

Paul Rawlings
- Tomball, Texas
2006

---

---

2007

Q. Dear Sir,

I read your site, it is very interesting. I have some question for regarding my plating line hope you will throw some light on it. I have 20 years experience in electroplating. We are in the field of manufacturing connectors in India.

I want to know cleaning cycle over aluminum & aluminum die castings for Electroless Nickel plating as undercoat & cadmium plating as overcoat followed by olive green passivation. Aluminum die casting used of 6061 grade & 7075 T-6 grade. We are facing Blistering problems.

Please suggest a cleaning cycle for both of the processes.

At present our cleaning cycle is as follows:

1) Degreasing 1) TCE With Ultrasonic 10 MIN.
2) SOAK CLEAN 1) sodium carbonate ⇦ this on eBay or Amazon] :30-35 g/l 2-3 MIN
   2) Tri sodium phosphate: 30-35 g/l
   3) Teepol: 1.5 -2. ml/l
   4) Temp: 40-60 °C

3) Rinse Plain Water 30-45 sec.

4) Desmutting 1) Nitric acid com.: 95% 1.5 - 2 min.
   2) Hydrofluoric acid: 5%

5) Rinse Plain Water 30-45 sec.

6) Albond dip ALBOND DIP (CMP): 100 %, Density 10 1 - 1.5 min.

7) Rinse Plain Water 30-45 sec.

8) 80% HNO3 Nitric Acid (80%) 1 min.

9) Desmutting 1) Nitric acid com. : 95 % 1.0 - 1.5 min.
   2) Hydrofluoric acid : 5 %

10) Rinse Plain Water 30-45 sec.

11) Albond dip ALBOND DIP ( CMP) : 100 %, Density 10 20-30 sec

12) Rinse Plain Water 30-45 sec.

13) Electroless nickel Atotech 15-20 min. 2.5 -3 micr.

14) Rinse Plain Water 30-45 sec.

15) Rinse Plain Water 30-45 sec.

16) Cadmium plating Metal 22 g/l,T. CN 150 g/l 35-45 MIN. 10-12 micron.

17) 0.5 % HNO3 0.5 % HNO3 30 sec.

18) Olive drab pass., Atotech 35-40 sec.

19) Drying Centrifugal dryer 5 min.

20) OVEN TEST 150 °C 1 hour.

21) Inspection Under 4 x magnification.

I am sorry for asking question without cleaning cycle. Above cleaning cycle for your information. We have blister problem after oven test. Blisters are very micro in nature, sometimes we can not see with naked eye. My customer is checking this jobs at 10x

So kindly suggest any specification you have for inspection.

Components have burr inside the jobs. Is it a cause for blisters?

Please STUDY AND GIVE SOME GUIDELINES WHICH WILL BE HELPFUL TO US.


Thanks,

KAMLESH M.BHATT.
DEPUTY MANAGER - PUNE, MAHARASTRA, INDIA

---

---

---

---

Q. I have been reading the string of messages and responses and I have a question. What specification calls for 1000 hrs of salt spray?

Manuel Robles
- San Diego, California USA
May 19, 2015