Ionitech's Ion/Plasma Nitriding

Ion/ Plasma Nitriding

Gas Nitriding

Process temperature range

300 – 700 C

500 – 600 C

Process time range

from 1 minute up to 100 hours (most often process times: 6 – 12 hours)

5 to 100 hours

Process gases

N2; H2; Ar (special cases); NH3*;

N2; H2; NH3;

Achieved surface hardness

Depending on the steel grade: 400 – 1300 HV

Depending on the steel grade: 400 – 1300 HV

Compound zone (white layer)

Most often gamma-prime phase (γ’), but can be controlled better to form epsilon-phase (ε) or no white layer.

Typically, consists of a mixture of both epsilon (ε) and gamma prime (γ') phases. Epsilon phase is bigger.

Diffusion layer

Depending on the steel grade: 0.02 – 0.8 mm

Depending on the steel grade: 0.02 – 0.8 mm

Possibility for Post Oxidation

yes

yes

Advantages

• Very low consumption of gases (90 % lower compared to gas nitriding **)
• Sputter cleaning (atomic level cleaning)
• Nitriding of stainless steels without prior depassivation
• Nitriding of stainless steels at lower temperature to keep the corrosion resistance
• Better control on the formation of the compound zone (white layer)
• Possibility for mechanical masking of surfaces to avoid nitriding
• Lower energy consumption
• Lower Effluent gas emission
• Environmentally friendly, no toxic byproducts

• Less precision needed in the arrangement of the parts in the chamber

Disadvantages

• Arrangement of the parts in the chamber precision needed

• In some cases, gas nitriding requires mechanical removal of the white layer because of risk of fatigue crack initiation (grinding post-process)
• retort of the gas furnace gets nitrided after a period of time
• High consumption of gases (90 % lower compared to gas nitriding **)
• Prior depassivation needed for nitriding stainless steel grades
• Higher energy consumption
• Higher effluent gas emission

Ion/ Plasma Nitriding

Salt-Bath Nitriding

Process temperature range

300 – 700 C

550 – 600 C

Process time range

from 1 minute up to 100 hours (most often process times: 6 – 12 hours)

1 – 4 hours

Process gases

N2; H2; Ar (special cases); NH3*;

cyanide/cyanate salts

Achieved surface hardness

Depending on the steel grade: 400 – 1300 HV

Depending on the steel grade: 400 – 1300 HV

Compound zone (white layer)

Most often gamma-prime phase (γ’), but can be controlled better to form epsilon-phase (ε) or no white layer.

Typically, consists of a mixture of both epsilon (ε) and gamma prime (γ') phases. Almost no control over the formation.

Diffusion layer

Depending on the steel grade: 0.02 – 0.8 mm

Depending on the steel grade: 0.1 – 0.5 mm

Possibility for Post Oxidation

yes

yes (separate bath)

Advantages

• Better Control over the process
• Low-temperature treatment of stainless steel grades to keep their corrosion resistance
• Ion nitriding can be precisely controlled and treat specific areas of a part, avoiding surfaces that don't need to be hardened.
• Eco-friendly and safe process

• Faster processing times.

Disadvantages

• Highly toxic and hazardous
• Disposal of salts following regulations.
• No possibility of masking surfaces that must not be nitrided

Ion/ Plasma Nitriding

Carburising

Process temperature range

300 – 700 C

850 – 950 C

Process time range

from 1 minute up to 100 hours (most often process times: 6 – 12 hours)

4 - 10 hours

Process gases

N2; H2; Ar (special cases); NH3*;

CO, CH4;

Achieved surface hardness

Depending on the steel grade: 400 – 1300 HV

750 - 850 HV

Compound zone (white layer)

Most often gamma-prime phase (γ’), but can be controlled better to form epsilon-phase (ε) or no white layer.

No white layer

Diffusion layer

Depending on the steel grade: 0.02 – 0.8 mm

Depending on the steel grade: 0.2 – 1.5 mm

Possibility for Post Oxidation

yes

no

Advantages

• No post-nitriding processes needed – nitrided parts are ready to use when taken out of the chamber.
• The low temperature allows for nitriding of precise parts.
• The formed white layer provides better wear resistance and corrosion resistance.
• Possibility for masking of surfaces that mustn’t be nitrided.
• Eco-friendly and safe process

• Provides deeper case depths.

Disadvantages

• Although it creates higher hardness for some steel grades, compared to nitriding results, adhesive wear resistance is worse, because of the absence of white layer, that lowers the friction coefficient
• It is a treatment limited to carbon steels and some alloy steels.
• Post-carburizing heat treatments are needed because of the phase change of the material during carburising at such high temperatures
• High temperatures can distort the parts and tools and will require post-carburizing grinding and machining