Boron carbide (B₄C) ranks among the hardest materials known to science — only diamond and cubic boron nitride exceed its Vickers hardness of 2800–3200 HV. At a density of only 2.5 g/cm³, roughly one-third that of steel, it delivers a hardness-to-weight ratio that no other engineering material can match.
That extreme profile makes B₄C the standard material for lightweight ballistic armour (body armour plates, helicopter cockpit shielding), abrasive blast nozzles, sandblasting tips and slurry-pump wear parts. It is also used as a neutron absorber in nuclear reactors, where its high boron content provides excellent neutron-capture cross-section without excessive weight penalty.