Knowledge of the boron

When people still do not know what is the boron, they had already deal with boron. Around 200 BC, ancient Egypt, Rome, and the Babylonians had made of borax glass and welding Gold. Chinese ancient alchemists had been used borax, too. But the chemical composition of borax is still a mystery until the early 19th century. Boron for non-metallic elements. Elemental boron has amorphous and crystalline two froms. The former is brownish black to black boron powder; latter was jet-black to silver-gray, show remarkable metallic luster, the hardness is like diamond, but with very high resistance, the electrical conductivity increases with temperature increasing. Amorphous elemental boron density is 2.3 g / cm 3 (25-27 ° C); crystalline elemental boron density is 2.31 g / cm 3. Boron melting point of 2300 ° C, a boiling point of 2550 ° C.

Boron crystalline have a plurality of allotrope, they are use the B12 icosahedron as the basic structural unit. This icosahedral is composed of 12 B atoms and 20 closer to equilateral triangle facet intersect 30 edges and 12 corners, each corner of the top of an atom B occupies. The B12 icosahedron connected in different ways, the key is also different, the formation of boron are also with different types of crystals, such as ±-diamond boron.

Boron is relatively stable at room temperature, amorphous elemental boron can be slowly oxidized in air, can be spontaneous about 800 . Boron can not react with hydrochloric acid or hydrofluoric acid, but can be a mixture of hot concentrated nitric acid and sodium dichromate and sulfuric acid slow erosion and oxidation. Hydrogen peroxide and ammonium persulfate can also be slowly oxidation crystalline boron. Eutectic boron and alkali metal carbonates and hydroxides mixture, all the various forms of boron are completely oxidized. The role of the chlorine, bromine, fluorine and boron to form the corresponding boron halide. At about 600 ° C, boron with sulfur violent reaction and generated a mixture of boron sulfide.

Boron heated to above 1000  in a nitrogen or ammonia gas generated boron nitride ,1800-2000  when formed, boron and hydrogen is still not react. Boron and silicon in the reaction above 2000  boride silicon. At high temperatures, the boron can react with many metals and metal oxides, to generate metal boride. Boron at 600 to 1000 ° C, can react with sulfur, tin, phosphorus, arsenic reaction; at 1000 ~ 1400 ° C, with the nitrogen, carbon, silicon effects, under high temperature boron also react with many metals and metal oxides, metal boron compounds. These compounds are generally high hardness, refractory, and high electrical conductivity, and chemically inert substances, often with special properties.

The boron has the characteristics of the low density, high strength and a high melting point, it is widely used in the field of metallurgy and materials by metal powder supplier. Boron neutron absorption capacity is particularly strong, and combined with a plastic or aluminum, is an effective neutron shielding material. Rod and strip boron steel is used as the control rods in nuclear reactors. Boron fibers used in the manufacture of the structural material of the composite material and the missile rocket. Boron at high temperatures is particularly lively, often used to produce metallurgical degasifier, heated treatment of wrought iron and the increased alloy steel high temperature robustness. Boron products: boride (boron tribromide; titanium diboride; chromium diboride; boron nitride; 99.99% of hexagonal boron nitride; 99.9% of hexagonal boron nitride), and boron alloy boron (boron, copper alloy; steel alloy). In agriculture, the boron can be made fertilizers, also can be good herbicides. Boric acid has a clean sterilization effect. Borax is also used in the glass industry.

Source:http://www.mhcmp.com