Where the
world gathers for metal finishing
Q&As since 1989


-----

Enviro coating for stainless fasteners?

I am looking for enviro coating on ss304 fasteners. it should not rust or change when it is dipped in 1.3 sp.gr.sulfuric acid @ 60 degrees for 72 hours.

Kaidala Sathyanarayana (Pavan KS)
plating shop owner - Bangalore, Karnataka, India
May 20, 2011

---

May 22, 2011

Hi, Kaidala. This is a difficult exposure. What does "enviro" mean to you in this context? What type of coatings are you suggesting be avoided? Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

---

You could perhaps try titanium based PVD coatings.

H.R. Prabhakara - Consultant
Bangalore Plasmatek - Bangalore Karnataka India
May 25, 2011

---

I am not clear about the Enviro coating.

There are coatings which could withstand 1.3 sp.gr.sulfuric acid @ 60 degrees for 72 hours.

Sankara Narayanan.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note Nov. 2017: The good doctor has a fascinating blog at https://advancementinscience.wordpress.com)
May 31, 2011

---

July 13, 2011

I need the plating details that can be done on ss304 fasteners that satisfy the following requirements.
it should not rust or change when it is dipped in 1.3 sp.gr.sulfuric acid @ 60 degrees for 72 hours.
this is very important for us.

pls help me out with the information.

thanks
PAVAN

Pavan KS
plating shop owner - Bangalore City, Karnataka, India

---

July 15, 2011

I am always slightly puzzled when designers specify stainless steel and then want a coating to prevent corrosion!
There are many grades of SS (about 50 standard types) and the problem is best avoided by using the right type from the start.
Although 304 is not the best choice at the concentration stated, it is worth trying. You may find the attack in 60 hr is acceptable - it certainly will not rust.

You may find this link useful

www.bssa.org.uk/topics.php?article=33

Geoff Smith
Hampshire, England

---

July 14, 2011

As I mentioned earlier Titanium based PVD coatings should serve your purpose. These coatings are deposited in a vacuum chamber. Unlike electroplating this is a batch process. It is a dry process and environmentally friendly. The components are cleaned and dried before loading inside the vacuum chamber. Plasma is produced on a titanium cathode by applying appropriate voltage. Titanium ions or atoms come out of the cathode and get deposited on the components. In the presence of a reactive gas like nitrogen TiN is formed on the components. Similarly other substances can also be deposited. These coatings are hard and stable. It is very difficult to remove them either in acids or alkalies commonly used, one needs a special process.
There are a few coating centers in and around Bangalore which can do the job.

H.R. Prabhakara - Consultant
Bangalore Plasmatek - Bangalore Karnataka India