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topic 5007

Stripping titanium nitride PVD coatings



A discussion started in 2000 & continuing through 2012

(2000)

Q. Seeking a source of a stripper for PVD coating (titanium nitride). A variety of substrates is involved. Thanks

Ken Lemke
Ken Lemke
Burlington, Ontario, Canada


(2000)

A. Concentrated acids, especially hydrofluoric, will dissolve PVD TiN. It is even more difficult remove CVD TiN due to the more conformal surface. Unless your substrate is glass or ceramic, there is a strong likelihood the substrate will be significantly damaged removing the nitride with this method. Sorry, that is one of the advantages TiN surfaces--the fact that they are so hard to remove!

Dale Woika
Bellafonte, Pennsylvania


(2001)

A. A combination of alkali and hydrogen peroxide are useful for removing titanium nitride from stainless steel (I would recommend a 5% (w/v) of KOH to which is gradually added approx. 30% hydrogen peroxide solution (no more than 20 L to a 100 L KOH solution). The H2O2 is added slowly so as to control the temperature of the etch solution. If the temperature of the solution exceeds 30 deg C oxygen is evolved rapidly and the solution will foam up uncontrollably. Ammonia solution can be substituted for alkali (KOH/NaOH) for etching titanium nitride from aluminium.

Brendan Timmins
- Limerick, Ireland



(2002)

Q. Also seeking a solution for removing PVD TiN. Without damage to the underlying ceramic (AlN) substrate.

Jason
- Daytona Beach, Florida, USA


(2003)

A. I run a PVD job shop in India.

Most common method for stripping Titanium Nitride is to use 30% or 50% hydrogen peroxide (H2O2) - this works with stainless steel and HSS substrates. But this is slow; will take up to 8 hours. Use a container big enough to allow for foaming and also keep it ventilated; keeping it in sunlight speeds it up.

Catalysts such as NaOH and EDTA speed up the process, but needs more control.

For stainless steel 304 grade, nitric acid + HF works well - over in minutes - but you have to be careful with concentrations (we use 3:1 ratio) to avoid etching of substrate; with 410 grade; we tried, there was heavy etching. Right now we are staying with H2O2

Caution: do not use with tungsten carbide.

Kuppu Swamy
- Chennai, India



To minimize searching and offer multiple viewpoints, we've combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.



How to strip titanium nitride/or titanium aluminum nitride from carbide

(2005)

Q. This is a problem confusing me for a long time. About a month ago we coated TiAlN on carbide by PVD sputtering method, unfortunately there is a metal layer inside the coating because of the nitrogen pause during the coating. Now I could not decorate the TiAlN without etching carbide, which is very sensitive to acid or alkali. Anybody could help me?

Jolin [last name deleted for privacy by Editor]
titanium coating technology - New York, New York, USA


(2005)

A. Try heating the parts - the difference in the rate and amount of expansion may crack the coating. It has been years since we have done this but I am guessing it was about 1500 F or so. Most of the coating flaked off nicely. The remaining residue was easily removed with sandblasting.

Thomas J. Walz
- Tacoma, Washington



(2005) -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am looking at stripping a PVD Titanium Nitride coating from a carbide substrate without of course damaging the carbide and would like all the assistance I can get. At this point stripping from stainless steel is no problem at all.

Thank you

Chris Flattery
PVD coatings - Washington Twp., Michigan



September 11, 2008

Q. I work for a PVD company that deposits hard coatings such as TiN or TiAlN on steel substrates. We developed a stripping process which is a mixture of NaOH and hydrogen peroxide (H2O2).
First, I am trying to figure out what is the waste produce by the stripping reaction? Second, when I transferred the process to production I have had some difficulty in controlling the reaction. In our lab, even at high temperature (~70 °C), the foaming doesn't get out of control but in production we have had a few overflows due to excessive foaming. One difference that was identified is the use of a steel tank in production as opposed glass beakers in the lab. Any thoughts?

Steve Guetre
engineer - Montreal, Canada


September 12, 2008

A. I am a bit surprised that you did not have any problem in the lab at 70 °C.
The breakdown from heat of H2O2 appears to be logarithmic. It becomes self destructing extremely rapidly at some temperature. I have seen it become nearly explosive. I bear the burn scars from it.
In production you may have more material to strip per unit of solution . Heat is a product of the breakdown.
If units are comparable, then I will guess that in production you are generating more heat than the tank can get rid of whereas in the lab the heat transferred to the atmosphere faster for some reason.
Possible solutions would be to strip less material at one time paying close attention to the initial temperature, or adding a cooling coil that would kick in at a given temp to control the temp rise.

James Watts
- Navarre, Florida



November 19, 2010 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear sir,
we are doing CVD TiN coating with (aluminium alloy as base metal) in our industry and I wish to know how can I remove this coating in any case without affecting the base metal.
Regards
Nitin

Nitin Sardana
Patiala, India


November 19, 2010

A. Hi, Nitin.

We appended your inquiry to a thread which hopefully answers it. Please see the response from Brendan Timmins above.

Another good thread about stripping titanium nitride is letter 11499. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



October 1, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Two questions:

1 - looking for solution on stripping TiN from Titanium substrate
2 - looking for solution on stripping AlCrN from Carbide substrate where the main problem is Cobalt leaching

Ilcho Aksovski
- Clinton, Michigan, USA

----
Ed. note: These threads about stripping TiN are already long and a bit meandering, so please see letter 53089 for your second question. Thanks.



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