Also known as ion nitriding, is a thermochemical process used to enhance the properties of metal components made of steel, stainless steel, cast iron, titanium or nickel alloys.

Increase mechanical properties of parts: surface hardness, wear resistance, corrosion resistance and fatigue resistance. Decrease fatigue, corrosion, galling, wear and premature components failures. Avoid conventional heat treatment distortions and extra griding operations. That means lower overall manufacturing costs. Avoid usage of toxic gas and chemicals such as ammonia or cyanide salts.

The plasma nitriding process is based on the principle of nitrogen diffusion into the metal's surface. Briefly, the process consists of: Place the metal parts into a vacuum chamber. Generation of a controlled atmosphere of nitrogen gas (N2) and hydrogen gas (H2) atmosphere in this vacuum chamber. Raise the temperature of the parts in the range of 390°C to 600°C (734°F to 1112°F), depending on the material and the expected results. Applying an electric field to the mixture, for ionizing the gas atoms. Ion bombarding: Nitrogen diffuses into the steel surface. The diffused atoms form nitride compounds with the alloying elements of the metal, mainly iron nitrides (Fe3N y Fe4N). It is important to mention that the final hardness result is highly dependent on the alloying elements present in steel, which are aluminum, titanium, vanadium, molybdenum and chromium.

Nitriding is the diffusion of nitrogen alone, and it is focused on the diffusion zone rather than the white layer. The diffusion zone provides high hardness and fatigue resistance. Is normally performed at temperatures between 390°C and 550°C Nitrocarburizing is the diffusion of nitrogen + carbon, and it is focused mainly on creating a thicker white layer. It is usually performed at creating a thicker white layer (but will also produce a diffusion zone). Is normally performed at 550°C to 580°C

Absolutely, yes. Ferritic carbonitriding is the diffusion of nitrogen + carbon into the part. This process is suitable when you need to create a thicker white layer and, in addition, produce a diffusion zone. The introduction of carbon into the surface saturates the chemical composition of the steel, converting it into a compound and thus generating a thicker white layer. Keep in mind that when the preferred mechanism of the part is sliding, a thicker white layer is always better; however, being a brittle layer, this can be the starting point of a crack. the right depth of white layer needs to be determined.

Nitriding depth ranges from a couple microns on highly alloyed materials, up to 0.7 millimeters on low alloyed ones.

Unlike traditional case hardening methods like carburizing, nitriding takes place at lower temperatures, which are below the transformation temperature of steel during heating. Both, Nitriding and nitrocarburizing could be called Ferritic processes, while carburizing could be called an austenitic process because of the high temperature it takes place at.

Because the nitriding potential does not depend on the process temperature but on the control of the gas atmosphere. This means that it is sufficient to apply the correct recipe to obtain repeatable results.

Plasma nitriding is used in a wide range of industries where require to improve the durability and performance of metal components in demanding operating conditions. Automotive: such as engine parts (e.g., crankshafts, camshafts, piston rings), transmission components, gears, and other high-wear parts. Aerospace: in critical components manufacturing, such as landing gear parts, turbine blades, and engine components. Oil and Gas, including valves, pumps, and drilling equipment, that are subjected to harsh and corrosive environments. Energy power generation, such as turbines and generators. Firearms and Defense: Some firearm components, such as bolt carriers. Industrial manufacturing: Tools, dies, and injection molds used in manufacturing processes. Cutting and Forming Tools used in cutting, shaping, and machining processes, such as drills, taps, and end mills. Medical Device: For manufacturing biocompatibility components, such as surgical instruments and orthopedic implants.

When you plasma nitride/nitrocarburize a part, and you look at the cross section under the microscope, you will find two distinguishable layers under the surface. The outermost layer is called ‘compound zone’ and it looks white once it has been etched with Nital and placed under the microscope. That is the reason one refers to such a first layer as the compound zone or the white layer. In this layer, the N2 content of the part is so high that the whole surface transforms into a composite of iron and other types of nitrides. It is a ‘ceramic-like’ material which has a low coefficient of friction, high hardness but also high brittleness. The usual thickness of this layer varies from 0 to 25 microns. Typical for plasma nitriding is maximum 15 microns (could be more) and average between 5 and 10 microns. The second layer is called the diffusion zone. In this zone, which is under the white layer (if any), is an area where you can find many finely dispersed nitrides. This layer can reach depths up to 0.7mm also depending on how it is measured and what steel grade one is using. Under the microscope this looks like a darker area than the original material.

Case depth is an arbitrary concept. That means that every designer defines it as he/she thinks is best for their product. Most common definitions: a. The distance from the surface at which the hardness of the layer drops to a value equal that of 110% the core hardness. b. The distance from the surface at which the hardness of the layer drops to a value equal that of the core hardness plus 50 Hv (Vickers hardness) c. The distance from the surface at which the hardness of the layer drops to a value equivalent to 50 HRc. d. The distance from the surface where the darker area of the diffusion zone disappears measured optically under the microscope. Normally, case depth for any Nitrided, or Nitrocarburized (FNC) layer varies from 30 microns for very high alloyed steel like HSS or stainless steel, to 0.7mm in unalloyed steels. For 4140 types of material, a typical case depth varies from 0.15 to 0.3 mm depending on the application.

The nitrided/nitrocarburized layer is thin, and the hardness measurement is a test that measures how much a material deforms under certain force applied by certain geometry. HRc is a scale that applies 150 kg of force using a diamond indenter. When you use the HRc scale to measure the hardness of a part, you are not only measuring the hardness of a thin case, you are also measuring the hardness of the material below it. That is why HRc is not the right way to measure a nitrided case, unless, you as a designer choose to do so, because it anyway gives you an indication of the hardness of the layer and the depth of the nitrided case. The typical test used to measure the hardness of a nitrided layer is Hv (Vickers hardness test). The Vickers’s scale has different forces that can be used from 10 grams up to 1 kg force. Typically, the force used is of 300 grams and its syntaxis is HV 0.3

One of the great advantages of the plasma nitriding furnace technology is that are pieces of equipment that do not destroy themselves as other types of furnaces do, so the maintenance cost is negligible under normal circumstances. The basic utilities for their day-to-day operation are: Compressed Nitrogen tank | Linde, Air liquid, Praxair are common suppliers. Compressed Hydrogen | Can be bought in bottle bundles. Power is 480VAC 3ph, + Neutral + Ground (115kW total power) Chilled water for cooling of flanges and power supplies. We can always provide a provide a closed loop stand alone chiller from a known brand.

At ION HEAT we manufacture your plasma nitriding furnace according to your production requirements: size, components, utilities, metallurgical processes, extras. Therefore, the manufacturing time is 6 to 8 months, from the moment we receive the PO and down payment, until the unit is picked up at our plant (lead times may be affected by eventualities in the supply chain).