The nitriding cycle begins by placing the product into the vacuum chamber and evacuating the chamber to a desired vacuum pressure. Upon reaching the desired vacuum, the unit is back-filled with a process gas to begin the preheating cycle. The standard preheating cycle ranges in temperature from 400 to 580◦C. When the preset heating time has elapsed, the product is subjected to an ion bombardment to clean impurities from the surface. The process gas is ionized by a voltage that is applied to the product. This ionized gas collides with the product removing impurities from the surface and preparing the product for the nitriding process to begin. When the product surface has been cleaned sufficiently, the nitriding cycle begins.

A controlled flow of nitrogen, hydrogen and methane are introduced into the chamber and ionized by the voltage applied to the product. The plasma generated by the ionization envelops the surface of the product with a blue-violet glow. The combination of the heat and energy of the plasma cause the gasses to react with nitride forming elements in the steel.As the process gasses react with the elements in the steel, a wear resistant layer is formed. This layer can consist of a gamma prime Fe4N or an epsilon Fe2-3N composition depending on thepercentage of each gas in the chamber. The choice of the particular composition would depend on the application of the product in the field.In addition to increasing the steel's abrasion resistance, the nitride layer also improves the fatigue strength and reduces the friction coefficient. The nitriding cycle is continued for 2 to 72 hours until the desired case depth of 0.002" to 0.024" is achieved. The processing time is dependant on the composition of the steel being nitrided and the required case depth. Low alloy steels are generally processed for longer cycle times.

The Plasma Tech PlasNit™ process is a cost-effective alternative to conventional gas nitriding, with economical masking and reduced cycle time.After a vacuum is established in the chamber, precisely controlled amounts of hydrogen, nitrogen and other gases are introduced into the chamber.DC electrical current is applied to the cathode, producing a “glow discharge.” This “glow discharge” ionizes the hydrogen and nitrogen, and the electrical potential between the anode and cathode accelerates the movement of ionized hydrogen and nitrogen toward the components being treated.

PlasNit™ provides hardness ranges from 55 to 70+ Rockwell C. The PlasNit™ process is also virtually distortion-free. Because of reduced processing temperatures, your components achieve greater surface hardness while maintaining dimensional stability. In-process stress relief is a vital part of the PlasNit™ process. Masking is accomplished by simply interrupting the glow seam in the area to be masked. It is simple and cost effective with no plating involved.

The features and benefits of the process include:

• Nitride Case - High Hardness (600-2,000HV) (70+ Rc), Anti-Seizing, Anti- Galling, Anti-Welding, and Hot-Hardness.

• Solid State Solution - Fatigue Properties Increased Tensile and Yield Strength, Stiffness, Elongation Maintained, Residual Compressive Stresses.

• Distortion & Dimensional Control - Uniform Growth, Up to 10% of Case Depth, No Transformation Cooling, Reduced Treatment Temperature, Reduced Distortion.

• Versatile - Case Depths .002 to .020 inch, Ability to Retain Core Properties, Ability to be Selectively Applied, No Plating or Painting Required.

 

PlasNit - OxyNit

Our PlasNit - OxyNit process supplements the ion-plasma nitride case with an oxide layer in order to enhance the tribological and corrosion properties of your components. Depending on the substrate material and the resultant ion-plasma nitride case, your component surface will develop an ebony-type finish. The oxide layer can improve sliding wear characteristics by providing a semiporous lubricant retention layer. A complex oxide layer can also be developed to improve the corrosion resistance of your nitrided component. Depending on the material and nitride process, the oxide layer can double or triple the corrosion resistance of your treated components.

Typical Plasma Nitriding Results Plasma vs. Gas nitrding Advantages of Plasma Nitriding vs. Traditional Gas & Salt Bath Nitriding Plasma nitriding imparts a hard wear resistant surface without brittleness, galling, or spalling. This eliminates costly cleaning or grinding to remove the brittle white layer associated with traditional nitriding.

A uniform glow discharge that envelops the entire surface achieves a consistent hardness and case depth. This is especially noticeable on complex geometries where gas nitriding case depths can benon-uniform.Plasma nitriding (H2+N2) least affects the surface finish of the product. Salt bath and gas nitriding, which uses ammonia (NH3) and phosphate for activation, will roughen a ground or polished surface.Plasma nitriding has a higher surface hardness and maintains your material's core properties due to the lower processing temperatures associated with plasma nitriding (900 - 950 Fahrenheit).Traditional nitriding operates at 975 -1075 Fahrenheit and can change the core properties of your material.More materials can be selected for plasma nitriding, including cast iron, mild steel, mold, tool, high speed and stainless steels.

Plasma nitriding is environmentally friendly. Plasma nitriding uses non-toxic precisely controlled gas mixtures. Traditional gas and salt bath nitriding uses toxic gasses, salts and ammonia that arehard to control and harmful to the workers and the environment.

Plasma vs. Chrome

Advantages of Plasma Nitriding vs. Chrome Plating Plasma nitriding imparts a hard wear resistant diffused layer to the surface without the problems encountered with most wet bath plating. Because plasma nitriding is a diffusion process it eliminates the problems of flaking, spalling, edge build-up, chipping and the cost associated with stripping and re plating the products. Cutting edges remain sharp during plasma nitriding and the uniform glow discharge enveloping all surfaces achieves a consistent hardness and case depth.The build-up associated with chrome plating that causes the rounding of edges and webbing at the base of cavities is eliminated with plasma nitriding. In some cases, grinding is necessary to remove the excessive build-up leading to additional production costs.The diffused case in ion nitriding provides good resistance to indentation which chrome plating does not offer. This allows plasma nitriding to be selected for a wider range of materials and

applications.

Plasma nitriding will improve the fatigue strength of your material. Chrome plating does not offer this benefit.

Performance of plasma nitrided hydraulic shafts in Europe has satisfied the requirements for corrosion and wear resistance vs. chrome.

Plasma nitriding is environmentally friendly. Plasma nitriding does not use any toxic substances. The chrome plating process uses hexavalent chrome which is a known carcinogen.

Plasma Nitriding Applications

Molds - Forging Dies

Trim Dies - Punches

Draw Dies - Stamping Dies

Extrusion Dies - Crank Shafts

Fuel Injection Components- Screws for Plastic Molding

Screws for Plastic Extrusion - Nozzles

Ejector Pins – Gears- Pump Shafts

Cams - Cam Shafts

The PlasNit™ treatment is well-suited for the following materials:

• Alloy Steels Containing (Cr, Al, Mo, V, W, Ti)

• Nitriding Steels

• Medium Carbon Chrome Steels

• Chrome, Chrome-Vanadium Steels

• Stainless Steels (300, 400, PH)

• Tool Steels

Applications that benefit from Ion-Plasma Nitriding include:

• Tooling for Die Casting, Forging and Extrusions

• Plastic Molds

• Metal Working

• Composite Tooling

• Power Transmission Components

• High-Performance Engine Components

• Hydraulic System Hardware

• Bearings

• Gears

• Powdered Metal Components