Dear all,
TiN coating is harder than Ti coating. But does TiN coating have the same corrosion resistance than Ti coating or is it less ? because Ti owes its corrosion resistance to the formation of a stable Titanium oxide layer. Does the addition of N slows down the formation of this passive layer ?
TiN itself is quite inert to lots of chemicals, but as a coating it may cause severe corrosion to the substrate materials.
When we talk about the corrosion resistance of a coating, we really need to think about (1) the coating/substrate as a whole system due to the presence of porosity and defects and (2) the corrosive environment the system is exposed to.
For example, TiN coated stainless steel, when being exposed to NaCl solution, can have galvanic corrosion issue due to coating porosity/defects and the susceptibility of stainless steel to localized corrosion. However, TiN coated titanium alloy, when being exposed to NaCl solution, can show pretty good resistance to corrosion.
Hope it will help.
Dear Dr Yang,
Thank you for answer. Suppose we are able to produce a TiN coating with very low porosity on stainless steel. And a Ti coating with also low porosity on stainless steel. Which system will be more corrosion resistant :
Ti-Stainless steel or TiN-stainless steel, assuming that ideally there is no porosity for both TiN coating and Ti coating ?
Basically, TiN is highly inert to acids, bases, solvents, and lots of corrosive solutions; surface passivation provides titanium and its alloys excellent resistance to corrosion. Titanium can withstand corrosion attack by dilute sulfuric and hydrochloric acids, chloride solutions, and most organic acids. However, titanium can be easily corroded by HF or some concentrated acids.
Corrosion is a complex process and can be affected by lots of factors. No one can give you a general answer without knowing the corrosive environment and conditions.
Also keep in mind, in the real world coating porosity (and/or defects) can be reduced, but is difficult, if not impossible, to be completely eliminated.
Anas - TiN coating has better corrosion resistance as compared to Ti coating. Furthermore since TiN coating has better corrosion resistance, it is also used on Ti metal and Ti alloys. Also TiN has better edge retension and chemical resitance properties, and thus, it is used extensively to coat stainless steel surgical and orthopedic components..
Dr.K
Anas
TiN is a better coating but if Ti coating id added over TiN coating you have a greater corrosion resistance protecting the underlying material.
However, youir question is vague as it does not relate to particular environment. Enviroment as such is an immportant issue for corrosion ressistance, and thus, enviroment must be included to clarify corrosion resistance of Ti or TiN.
Dr. K
Hi Dr K,
The environment is phosphric acid, sulfuric acid.
If TiN is resistant in those environment then how ? what is the mechanism that will TiN more corrosion resistant than Ti in this envrionment
Thank you
Anas
Anas
TiN is more harder and resistant while Ti coating on exposure becomes TiO2 which fills any porosity or distortion in TiN protecting the product from corrosion.
Anas, since you are possibly a researcher at the Polytech and thus you have excellent fascility to conduct experimentation, and thus, carry out texperiments with TiN , Ti, and TiN+Ti coated sample based on factorial design to get the first hand answers of your question and also others would be benefited from your conclusion. Good luck.
Dr. K
Hi Dr Kothari,
We are optimizing the corrosion resistance of coatings. I agree it is possible to use factorial design for that purpose. Thank you for your answer.
Anas
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