Chemical Properties
black cub; -200 mesh 99.5% pure; refractory material [KIR78] [CER91] [CRC10]
Description
Typical samples of CaB6 are nonstoichiometric, i.e. the
ratio of boron to calcium is not exactly 6:1, for example
the ultra-fine powders of CaB6 produced by some
researchers had B:Ca ratio of 5.91:1. It is an important
material due to its high electrical conductivity, hardness,
chemical stability, and melting point.
Physical properties
Calcium boride is a black,
lustrous, chemically inert powder with a low density.
Calcium hexaboride is insoluble in H2O, MeOH (methanol),
and EtOH (ethanol) and dissolves slowly in acids.
It has the cubic structure typical for metal hexaborides,
with octahedral units of six boron atoms combined
with calcium atoms.
Uses
Carbon hexaboride is used in the manufacturing of
boron-alloyed steel. Also, calcium hexaboride is used
as a deoxidation agent in production of oxygen-free
copper, which results in higher conductivity than
conventionally phosphorus-deoxidized copper owing
to the low solubility of boron in copper. Also, it can serve as a high temperature material, surface protection, abrasives,
tools, and wear-resistant material.
Preparation
Calcium boride can be formed directly from the
elements. Ca melts at 842°C and boron melts at
2076°C. Therefore, if a vapor of Ca metal at >850°C
(red-heat) is passed over crystals of boron, a gas–solid
reaction forms the desired boride. However, to obtain
stoichiometric compositions, it is better to heat the
well-mixed powders of Ca and B to obtain specific
compounds:
Ca+ 6B→CaB6
Flammability and Explosibility
Notclassified
