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Plasma nitriding experiment


Dear sir,

I research about plasma nitrocarburizing post oxidation. Please help me about this subject.

Sincerely yours,

Mahdi Mirjani
Iranian surface research and engineering centre - Isfahan, Iran


I am a university student performing an experiment in plasma nitriding. I propose to nitride a sample of mild steel using an oxyacetylene cutting process. I will use the torch to heat the specimen but instead of using oxygen for cutting I will inject nitrogen gas onto the specimen. I would like to know how long should I do this process e.g., 1hr, 2hrs, etc. I would also like to know if anyone has performed any similar experiments and what were the outcomes.

Thank you,

Dennis Ramsumair
- Trinidad and Tobago


Since air is 80 percent nitrogen, what you are proposing is not very different from simply heating the steel in the presence of air. It's difficult to see how anything out of the ordinary will happen, but keep us posted.

Bill Reynolds
Bill Reynolds [dec.]
   consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.


I feel that the hypothesis is incorrect. First of all, what you are proposing is not plasma nitriding (which is a vacuum process). Secondly, oxyacetylene is a mixture of oxygen and acetylene. The oxygen causes combustion of acetylene, otherwise there will be no flame. Basically, any combustion process involving oxygen is not suitable.

Mandar Sunthankar
- Fort Collins, Colorado


I am the poster of the question and would like to make a correction. Firstly I intend to use the plasma arc cutter to heat the metal and instead of using compressed air I propose to use the nitrogen gas at a lowered pressure.

Dennis Ramsumair
- Trinidad and Tobago


Dear sirs,

I previously wrote you concerning my experiment in the plasma nitriding process.What my experiment entails is the use of the TIG welding process to perform the nitriding by using nitrogen as the inert gas. Also I propose to make use of the plasma arc cutting process which will generate a plasma ,but instead of cutting the specimen I intend to inject a soft flow of nitrogen unto the specimen. My questions are 1)do you consider my experiment feasible? 2)Do you in your expertise, foresee any problems I may encounter during experimentation? 3)Can you foresee any applications for this type of research?

Dennis Ramsumair
- Trinidad and Tobago


It is feasible. Let me say up front that I am not a nitriding expert, but I can understand the basic processes, such as diffusion and how it procceeds. It a is time, temperature and ambient phenomenon. You need control on all three. have you read any literature on nitriding and understood the basic principles of nitriding and how it happens? Then compare it with what you are trying to do and then proceed with the experiment. Prevent any oxygen contamination because oxidation and nitriding will be competing processes. You may need a nitrogen box to conduct experiment. Do you have means to measure what you see on the surface?

Mandar Sunthankar
- Fort Collins, Colorado


Very interesting discussion on plasma nitriding : the original post and later correction, seem to be aimed at an experiment to cause plasma nitriding.

By the way, I have been making and using plasma nitriding systems for two decades now, and have extensively used this process for developing industrial processes. By a coincidence, prior to this line or work, I was engaged for a decade on plasma arc cutting also.

During the process of plasma arc cutting [prior to the development of "air plasma" it was mandatory to use nitrogen as the plasmagen [ or plasma forming gas] -the extraordinarily high temperatures and heat input of the plasma arc was able to cut up to 150 mm thick stainless steel. However in years of work, I never came across a single specimen that could show nitrided portions. Hence the idea proposed does not seem feasible to me.

Secondly plasma nitriding is not a vacuum-process as PVD or PACVD etc. are. The vacuum is used only for removing gaseous impurities and moisture which are detrimental to uniform nitriding. Plasma nitriding works only between 1 to 10 Torrs, which is a 'low pressure regime' -slightly below the atmospheric pressure.

In plasma nitriding diffusion is very fast and occurs well only under specific conditions, in the open atmosphere this kinetic activation of nitrogen gas does not work.

Also, nitrides of many types are formed at different temperatures, different durations, etc. A haphazard formation of nitrides could lead to formation of a white layer which is detrimental as it is multiphase type. Only a monophase structure is useful.

I have written a whole on-line course on plasma nitriding. Many users have provided positively reinforcing feedback.

Thus it seems unlikely that the proposed experiment would produce any interesting nor reliable results. Oxygen impurities will mar the whole process, for sure.

max babi
Max Babi [dec]
- Chennai, Tamil Nadu, India

(with great sadness we acknowledge the passing of the great
Sir Max [Mushtaque Ali Khan Babi] on March 15, 2015)

May 22, 2009


I am doing Research in Plasma Nitriding,could explain what is purpose of Hydrogen during plasma nitriding? is this reaction purpose?

Selvan A.Selvan
- Coimbatore,Tamilnadu, India

May 12, 2011

Our Product requires HV650 to HV720 with a case depth of 0.2 mm.
Material usage SKS 3.
Is this specification achievable for Plasma Nitriding process?

Eddie Peng
Purchasing Officer - Singapore

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