What kind of substance is boron carbide? Is long-term close contact harmful to the human body?
Boron carbide is toxic and irritating, so long-term close contact requires certain protective measures. For example, avoid inhalation of its dust and direct skin contact. Hard black shiny crystals. The hardness is lower than that of industrial diamond, but higher than that of silicon carbide. Less brittle than most pottery. Has a large thermal energy neutron capture cross section. Strong chemical resistance. Not attacked by hot hydrogen fluoride and nitric acid. Soluble in molten alkali, insoluble in water and acid. Relative density (d204) 2.508～2.512. Melting point 2350 ℃. Boiling point 3500 ℃.