Vacuum and plasma surface hardening are heat treatment processes carried out in low-pressure environments to impart high wear resistance and mechanical properties to steel components. Vacuum surface hardening involves heating steel above 1000°C in a vacuum to allow uniform hardening without oxidation. Plasma surface hardening uses ionized gas plasma to facilitate carburizing or nitriding steel at lower temperatures and shorter cycle times than vacuum carburizing. Both methods provide oxide-free, inter-granular oxidation-free surfaces but require higher initial capital costs than conventional carburizing.

1. Vacuum and Plasma Surface
Hardening
To meet the highest surface quality and mechanical
properties of the components.
Vacuum surface hardening
Plasma surface hardening

2. Vacuum Surface Hardening
Heat treatment process of steel carried out in a vacuum space
Low pressure and high uniform hardening temperature
(above 1000 °C)
Suitability
High wear and High load bearing applications

3. Vacuum Carburising Process
Evacuating and heating
Supplying Hydrocarbon Gas
Diffusion cycle
Quenching

5. Advantages of vacuum carburising
Oxide free surface
Absence of inter-granular oxidation
Better process and cycle flexibility
Excellent finish
Easy integration into manufacturing
Excellent hole penetration
Lower distortion
Shorter process times
Improved reliability and reproducibility

6. Disadvantages of Vacuum Carburising
Higher initial capital equipment cost
Part cleanliness is more critical

7. Plasma Surface Hardening
Plasma - High temperature ionized gas
Two types
Plasma carburising
Plasma nitriding

8. Plasma carburising process
Evacuating and heating
Supplying hydrocarbon gas
Generation of plasma
Diffusion cycle
Quenching

10. Advantages of plasma carburising
Shorter cycle times
No oxidation at grain boundaries
Lower process gas and energy consumption
Automation
Ability to treat hard to carburise materials

11. Disadvantages of plasma carburising
High initial capital equipment cost
Not applicable to bulk loads
Hollow cathode effect