The content of boron in the earth's crust is 0.001%. amorphous boron powder is a black or silver grey solid. The crystal boron is black, the hardness is second only to diamond, and the texture is brittle. Stable in air at room temperature, oxidized when heated to 300 ° C, and ignited at 700 ° C. Mr10.81. ρ = 2.37 g/cm 3 (amorphous); 2.34 to 2.46 g/cm 3 (crystal). The melting point is 2177 to 2301 ° C; the boiling point is 2550 to 2658 ° C. amorphous boron powder is named Boron and its name is derived from Arabic. The original meaning is "flux". It shows that the ancient Arabs already know that borax has the ability to melt metal oxides and is used as a flux in welding.
Amorphous boron powder is more chemically active than crystalline elemental boron. Since crystalline boron is very hard, it is often used instead of diamond to make cutting tools or drill bits. A small amount of boron is added during the metal smelting process, on the one hand as a deoxidizer to prevent oxidation of the metal at high temperatures; on the other hand, an alloy is formed to improve the mechanical properties of the metal. For example, boron copper is used to make control rods for atomic reactors.
As a boron fine chemical product, it is widely used in metallurgy, synthesis and aerospace. It is often used as a deoxidizer, an initiator for automobile airbags, and an ignition agent for rocket-launched fuel.
In October 2003, Chinese scientists successfully launched the ignition of amorphous boron powder into rocket-launched fuel. This move made the application of amorphous boron powder in China a military reality. Amorphous boron powder will become an important energy material, and its application in composite solid propellants has long been valued. As a solid fuel, the calorific value of boron is more than double that of carbon, about twice that of aluminum, and more than twice that of magnesium. Its volumetric calorific value is almost three times that of hydrocarbon fuel, and its density is only slightly lower than that of aluminum. The highest volumetric calorific value, boron should be the best non-metallic fuel in terms of its energy. Moreover, the amorphous boron has a greatly reduced ignition temperature due to its irregular shape and large specific surface area.