What are carburising and nitriding treatments ?

• Carburising and nitriding are thermochemical treatments, usually conducted at temperatures ranging from 800 to 900°C.

• These processes change the chemical composition of a low-carbon steel component so that subsequent fast cooling, by "quenching", produces a hard case combined with a softer core.

Carbostop C4 EW

Apply an even coat of C4 EW and allow to dry.

In many cases a single coat is sufficient.

For deep case depths a second coat is recommended.

Carbostop C4 EW

If any damage occurs on loading, touch up coating can be applied if there is enough drying time.

Carbostop C4 EW
Carbostop C4 EW forms an impervious barrier between the furnace atmosphere and the areas needing protection. After carburising the residue can be easily removed by alkali wash or mechanical means.

Advantages
Carbostop C4 EW protects metal as it makes a stabilised boric oxide vitreous coating. This system liberates no water of crystallisation on melting and gives a thicker protective glass layer.
The other stop-off paints use boric acid to form the glass, which liberates free water vapour on melting. This water can attack the furnace lining and gives a thinner protective glass layer.

Carbostop CW
Carbostop CW is our water based carburising stop off paint, designed especially for deep cases. Its special formulation requires higher than usual carburising temperatures.

Advantages
• Water based coating.
• Easy to apply, safer in use.
• No fumes.
• Wash brushes in water.

Nitrostop N4 - How does it work ?

Nitrostop N4 works by applying a layer of tin powder onto areas of metal to be protected.
This powder melts as the metal is heated up to nitriding temperature, sealing the surface from the nitriding gasses. After nitriding the coating is removed by mechanical means.
It is always recommended that two coats of Nitrostop N4 be applied although many heat-treaters successfully use only one.

Nitrostop NP

Plasma nitriding is now very popular, particularly in Europe, Nitrostop NP is specially formulated for stopping off components that are to be plasma nitrided.