finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing

HomeFAQsBooksHelpWantedAdvertiseForum
topic 60554

Nodule Problem in Cadmium Sulphate Plating


October 27, 2017

Q. We run a sulfuric-acid cadmium process on steel substrates in two separate identical tanks (two plating stations each). We recently dumped one of these baths, suspecting it had become contaminated. Since we made this new bath, we are getting extreme roughness in the form of tiny nodules, which form everywhere except the underside surfaces, as the parts are positioned on the rack. Under magnification, these nodules look like tiny brown warts. If you scrub the area with a scouring pad, the nodules shine up like the surrounding cad plate surface.

60554

We have ruled out cleaning. Parts from the other tank do not have this formation. Bath parameters for temperature, acid and metal content, etc., are in range and comparable to the other tank. No leaks identified. We filter these baths with .5-micron cartridges and have no detectable particulate in solution. Is this some sort of stress formation? So far the only difference we have detected between the two tanks is rectifier ripple: the roughness tank has 8%, while the other is only 1%. Even so, 8% doesn't strike us as alarming, but we are working to bring that down.

We use iridium-oxide inert anodes (instead of graphite), and our cadmium anode baskets are bagged.

Any ideas? Our chemical reps have all but given up.

Bruce Brady
- Lincoln, Nebraska, USA
  ^- Privately contact this inquirer -^



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.