iron 2 nitride, or ferrous nitride, is a nitride compound containing iron and nitrogen. It is a colorless, odorless, flammable solid and may cause mild explosions in the presence of air or humidity. It is a moderate explosive hazard and should not be used in open containers or near ignition sources.
It is a common additive to diesel fuel to improve its ignition properties. It is also used in colloidal solutions of magnetic iron nitride nanoparticles for the production of ferrofluids.
Nitride is a complex form of nitrogen with oxidation states that range from +2 to +6. The oxidation state of nitride is determined by the number of ions in the formula and its valence.
It can be made in a variety of ways, the most obvious being by heating spongy iron in dry ammonia. The optimum temperature is about 450deg C.
Another way of preparing nitride is by heating electrolytic iron foil in dry ammonia. This produces a gray powder of density about 6.25, and is soluble in dilute hydrochloric and sulphuric acids.
In a more concentrated solution, the reaction is vigorous at 350deg C. The resulting nitride peels off from the metal in thin flakes.
Nitrogen is a reducing agent and is found in some iron and steel alloys. It is slightly soluble in iron, but only when heated under high pressure and the temperature is above 1200deg C.
The nitride chemistry of nitrogen is the subject of much study. It has been discovered that under special conditions, such as the presence of a certain amount of carbon in the alloy, nitrogen can produce an extremely tough metal which is more resistant to wear and tear than if the element were removed from the alloy. It is this property that gives nitrogen its nickname as the “king of all reducing agents”.