Ion Nitriding Q&A, Problems & Solutions

A. I am not an expert in ion-nitriding nor have I ever done it. But I know a few things about plasma and these are just comments. I believe the purpose of plasma is to generate and accelerate nitrogen ions and shoot them into the steel (or implant them) which then diffuse to a desired distance depending on temperature. The plasma and temperature both need to be uniform around the part to impart uniform properties. When you stack parts, the plasma may not be uniform around the part. As a matter of fact, there will be no plasma where parts surfaces are in contact with each other.

In a hollow tube, you have a different problem. Depending on the diameter, you may need a separate anode inside the tube to sustain plasma uniformly.

A. Hello,

I have many years hands on experience with plasma nitriding and can confirm that you need to space the components apart. The spacing is critical if you are to get uniform nitriding and minimal movement. Also note that any spacers will have to be sufficient in number to support the column if you stack and will not contribute to distortion of the rings. Also, where the spacers touch the rings you will have a "soft Spot" which will not be nitrided at all.

Best Regards

A. Dear Sir,

The so called soft spot, where two components touch other, does it appears different/visible with eyes, is there a color difference, etc.

With Regards

A. Hi,

The purple seam is a natural outcome of the plasma reaction. It is called the sheath of the plasma and it is an indication that nitriding is proceeding well, if you are using the right gas chemistry i.e. 30% nitrogen and balance hydrogen.

If the colour of the seam changes to whitish, there is localised heating taking place...too much current is being used by the workpiece, tending to overheat. If the colour is pinkish, there is too much hydrogen. If it is bluish, there is too much nitrogen.

The hollow cathode phenomenon is not a surface phenomenon like the seam. The HCP occurs when you try to plasma nitride objects with deep holes, especially blind holes so that the gas movement through and through does not occur. This can lead to over-ionisation inside the hole where gas is entrapped, and can lead to uncontrolled heating. Actual melting of your workpiece can take place.

HCP is automatically controlled by microsecond switching when you use advanced design DC Pulsed Power Supplies.

Do let me know if this satisfies your query.

A. You work for him and can't make him listen, less can we. Do as he says. He's the boss, he pays the bills and he will suffer if the things do not come out right. If he really makes lousy technical decisions, he'll probably end up getting rid of it just to offer you the chance to buy it and prove how smart you are.

A. Persuasion my dear friend, persuasion. Your boss says don't fix it if it ain't broke. He may have reasons not to disturb what is working for his customers. So you may have to keep bugging him until one day he needs some improvement or a new solution, that when you jump and prove it. Also, it is prudent to use new process on a new product that is being introduced.

A. Dear Mr. Ron Pincombe,

Off hand I would say Carbon Nitriding uses high temperature in their process compared to lower temp for ion nitriding. Material you are handling will have more integrity than the ones processed in the old manner.

I am not familiar with your equipment but looks to me its a sort of PVD, Physical Vapor Deposition. I am really interested in this subject and I hope my answer will attract flack from more experienced readers.

I am not promising but I will give you inputs as I come across new infos or Ideas.

A. Dear Mr.Mario Billissi

see it is a ion nitriding process so,we need to use nitrogen to form nitrides in the matrix (case) of the material.

I think you know that we need some potential difference in order to ionise the gas . so,for this you are giving a positive charge to you are chamber and negative bias to you are working material in vacuum environment by giving high K.E to ionised ions . SO + is anode and - ve is cathode .

Regards,