Difference Between Cyaniding and Carbonitriding

The key difference between cyaniding and carbonitriding is that cyaniding uses sodium cyanide liquid, whereas carbonitriding process uses a gaseous atmosphere consisting of ammonia and hydrocarbons.

The case hardening process is the hardening of a metal surface while allowing the deep underneath of the metal to remain soft, and this process forms a thin layer of harder metal at the surface. There are different forms of case hardening processes, including cyaniding, carbonitriding, carburizing, nitriding, flame or induction hardening, and ferric nitrocarburizing.

1. Overview and Key Difference
2. What is Cyaniding
3. What is Carbonitriding
4. Side by Side Comparison – Cyaniding vs Carbonitriding in Tabular Form
5. Summary

What is Cyaniding?

Cyaniding is a type of case hardening process in which sodium cyanide is used. This is a very fast and efficient process that is mainly useful on low carbon steel. In this process, we need to heat the metal object or part of it at a high temperature in a bath of sodium cyanide. Thereafter, we need to quench the metal part, followed by rinsing it in water or oil in order to remove any remaining sodium cyanide on the metal surface.

Generally, the cyaniding process produces a thin hard shell. But this shell is harder than the shell produced from carburizing process. Furthermore, this process takes only about 20 to 30 minutes to complete. We can use this process typically on small parts, including bolts, nuts, screws and small gears. However, there is a major drawback of the cyaniding process, which is, the cyanides that we are using in this process are highly poisonous.

What is Carbonitriding?

Carbonitriding is a type of case hardening in which a gaseous atmosphere is used for the hardening process. We can observe that carbonitriding process is very similar to the cyaniding process, except this process uses a gaseous atmosphere.

Difference Between Cyaniding and Carbonitriding

Figure 01: Carbonitriding Furnace

The gaseous atmosphere we can use in this process include ammonia and hydrocarbon gases. The temperature to which we have to heat the metal object or part depends on the final step; if we are going to quench the metal surface, then the temperature should be around 445 to 885 Celsius degrees. If we are not going to quench the metal surface, then the temperature would be around 649 to 788 Celsius degrees.

What is the Difference Between Cyaniding and Carbonitriding?

Cyaniding and carbonitriding are two forms of case hardening processes that are useful in getting a hard surface on metal. The key difference between cyaniding and carbonitriding is that cyaniding uses sodium cyanide liquid, whereas carbonitriding process uses a gaseous atmosphere consisting of ammonia and hydrocarbons. Moreover, cyaniding involves temperatures around 871 to 954 Celsius degrees. But in carbonitriding, if we are going to quench the object the temperature should be around 445 to 885 Celsius degrees and if we are not going to quench the metal surface then the temperature would be around 649 to 788 Celsius degrees.

The following table summarizes the differences between cyaniding and carbonitriding.

Summary – Cyaniding vs Carbonitriding

Cyaniding and carbonitriding are two forms of case hardening processes that are useful in getting a hard surface on metal. The key difference between cyaniding and carbonitriding is that cyaniding uses sodium cyanide liquid, whereas carbonitriding process uses a gaseous atmosphere consisting of ammonia and hydrocarbons. In other words, the case hardening in the cyaniding process occurs in a liquid bath, while the case hardening occurs in the presence of gases.