Plasma nitriding technology and process

Plasma nitriding technology and process
1.Plasma nitriding
Plasma nitriding is a low-temperature thermochemical treatment process performed under glow discharge. This process is highly reproducible and metallurgically stable and is used in different industrial sectors to obtain better surface hardness, wear and corrosion protection, fatigue life and low friction on different steel alloys.
Plasma nitriding is a diffusion process that introduces nitrogen to the surface of a material. A uniform, very hard compound (white) iron nitride layer is formed on the surface of the steel, which improves the surface hardness and corrosion resistance of the steel and has good friction properties. By changing the process parameters, the thickness and phase composition of the layers can be adjusted.
The composite layer can be gamma-prime (γ-Fe4N) or epsilon-phase (ε-Fe2-3N), or both (when both phases are present – epsilon on top and gamma-prime below).
Different stages can be obtained by changing the process parameters. Epsilon-phase is more difficult than gamma-prime, but at the cost of less ductility.
A diffusion zone is formed beneath the white layer. It is composed of nitrogen-saturated ferrite with iron precipitate and alloying element nitride. The diffusion zone acts as a support for the white layer, increasing surface hardness and depth microhardness. Diffusion zones also increase the fatigue strength of the material.
The core hardness under the diffusion zone is basically the same as before treatment, and the steel parts maintain ductility, which is a major advantage of nitriding treatment compared with other treatments.
2. Industries where plasma nitriding is applied
Plasma nitriding technology is suitable for carbon steel, alloy steel, tool steel, sintered steel, stainless steel and other steel materials.
Automotive industry – crankshafts, camshafts, gears, pistons, cylinders, valves, valve springs, synchronizer rings;
Metal casting and molding industry – non-ferrous metal and alloy molds;
Forging industry – various forging dies (cold forging, die forging, open die forging);
Aluminum industry – casting and extrusion dies;
Plastic industry – extrusion machine screws, cylinders, injection molds;
Machinery manufacturing – shafts, spindles, slide rails, cold and hot rolling instruments, deep drawing dies and punches, pump cylinders, milling and drilling tools (milling cutters, companies, drills, taps, broaches, etc.);
Powder metallurgy – gears, bushings, synchronizing rings;
Power engineering – turbines, shafts, spindles, gears.
3. Post-oxidation treatment
Post-oxidation is a nitrided coating that forms a uniform coating on parts with a thickness of 2-3 microns (complete magnet phase – Fe3O4) and gives black a stylish color. This treatment increases the corrosion resistance of the parts many times and reduces the friction coefficient.
4. Equipment advantages
Plasma nitriding is the most environmentally friendly, safe and modern nitriding technology in the world today. Compared with traditional gas nitriding, plasma nitriding has the following advantages:
Cost-effectiveness
Shorten treatment time 3 to 10 times;
Energy consumption reduced by up to 50%;
Working gas consumption is reduced by 50 to 100 times;
Deformation
There is no or negligible deformation because ion nitriding is performed at lower temperatures and under vacuum;
Improve surface and surface hardness, maintain steel core hardness and ductility;
Excellent wear resistance
The composite area produced by the ion nitriding process is dense, non-porous, very hard, not brittle, and has a low friction coefficient;
Repeatable results and better control
The ion nitriding process is fully automated and computer controlled. The ion bombardment on the surface of the part heats the part so that the part is heated evenly;
Surface finish
Due to minimal deformation, no additional mechanical treatment is required;
Eliminates the need for stainless steel pre-passivation;
Masking
Surfaces requiring masking are easily masked with reusable mechanical masking devices or special paint used for masking – 100% effective;
Good hygiene and working conditions – the process is non-toxic and meets all modern environmental control requirements.

Learn More:

Vacuum brazing repair method for cracks

Vacuum brazing of ceramic and metal materials

Atmospheric Pressure and Vacuum Sintering of High Purity Dense MgO Ceramics