Cobalt borides are inorganic compounds with the general formula Co_xB_y. The two main cobalt borides are CoB and Co₂B. These are refractory materials.

Applications

Materials science

Cobalt borides are known to be exceptionally resistant to oxidation, a

chemical property A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.William L. Masterton, Cecile N. Hurley, ...

which makes them useful in the field of materials science. For instance, studies suggest cobalt boride can increase the lifespan of

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

parts when used as a

coating A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Pow ...

, imparting surfaces with higher

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

and

wear Wear is the damaging, gradual removal or deformation of material at solid surfaces. Causes of wear can be mechanical (e.g., erosion) or chemical (e.g., corrosion). The study of wear and related processes is referred to as tribology. Wear in ...

resistance. These properties have been exploited in the field of biomedical sciences for the design of specialized

drug delivery systems A route of administration in pharmacology and toxicology is the way by which a medication, drug, fluid, poison, or other substance is taken into the body. Routes of administration are generally classified by the location at which the substance i ...

Renewable energy

Cobalt boride has also been studied as a

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

for

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

storage and fuel cell technologies.

Organic synthesis

Cobalt boride is also an effective

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organ ...

catalyst used in organic synthesis. In one study, cobalt boride was found to be the most selective

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that ca ...

based catalyst available for the production of primary

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

s via nitrile reduction, even exceeding other cobalt containing catalysts such as Raney cobalt.

Preparations

Materials coating

Cobalt boride is produced under high temperature such as 1500 °C. Coatings of cobalt boride on iron are produced by

boriding Boriding, also called boronizing, is the process by which boron is added to a metal or alloy. It is a type of surface hardening. In this process boron atoms are diffused into the surface of a metal component. The resulting surface contains metal ...

, which involves first introducing a coating of FeB, Fe₂B. On to this iron boride coating is deposited cobalt using a pack cementation process. Cobalt boride nanoparticles in the size range of 18 to 22 nm have also been produced.

Catalyst

When used as a catalyst, cobalt boride is prepared by reducing a cobalt salt, such as

cobalt(II) nitrate Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

, with

sodium borohydride Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula Na BH4. This white solid, usually encountered as an aqueous basic solution, is a reducing agent that finds applica ...

. Prior to reduction, the surface area of the catalyst is maximized by supporting the salt on another material; often this material is activated carbon.