Boron , Usen -shaped, <5 μm, ≥94% , 7440-42-8

Synonym(s):
;Boric acid solution;Boron

CAS NO.：7440-42-8

Empirical Formula: B

Molecular Weight: 10.81

MDL number: MFCD00134034

EINECS: 231-151-2

PRODUCT Properties

• Melting point: 2300°C
• Boiling point: 2550°C
• Density: 2.34 g/mL at 25 °C (lit.)
• storage temp.: no restrictions.
• solubility: H₂O: soluble
• form: Powder
• Specific Gravity: 2.34～2.37
• color: Brown or dark
• Resistivity: 1.5E12 μΩ-cm, 20 °C
• Water Solubility: insoluble H2O [MER06]
• Crystal Structure: Trigonal (rhombohedral) a = 1017 pm α = 65°12' hR105, R3m, β-B type
• Merck: 13,1333
• Exposure limits: ACGIH: TWA 2 mg/m3; STEL 6 mg/m3
• Stability: Stable. Substances to be avoided include strong oxidizing agents and strong acids. May decompose on exposure to air - store under nitrogen. Highly flammable.
• InChIKey: UORVGPXVDQYIDP-UHFFFAOYSA-N
• CAS DataBase Reference: 7440-42-8(CAS DataBase Reference)
• NIST Chemistry Reference: Boron(7440-42-8)
• EPA Substance Registry System: Boron (7440-42-8)

Description and Uses

Boron was discovered by Sir Humphry Davy and J.L. Gay-Lussac in 1808. It is a trivalent non-metallic element that occurs abundantly in the evaporite ores borax and ulexite. Boron is never found as a free element on Earth. Boron appears as charcoal-grey pieces or black powder or as crystalline; is a very hard, black material with a high melting point; and exists in many polymorphs.

Boron has several forms, and the most common one is amorphous boron, a dark powder, non-reactive to oxygen, water, acids, and alkalis. It reacts with metals to form borides. Boron is an essential plant micronutrient. Sodium borate is used in biochemical and chemical laboratories to make buffers. Boric acid is produced mainly from borate minerals by the reaction with sulphuric acid. Boric acid is an important compound used in textile products. The most economically important compound of boron is sodium tetraborate decahydrate or borax, used for insulating fibreglass and sodium perborate bleach. Compounds of boron are used in organic synthesis, in the manufacture of a particular type of glasses, and as wood preservatives. Boron filaments are used for advanced aerospace structures, due to their high strength and light weight.

As early as 1959, boron filaments were introduced as the first of a family of high-strength, high-modulus, low-density reinforcements developed for advanced aerospace applications. A process was engineered by Avco Specialty Materials (Lowell, Massachusetts) and the U.S. Air Force to manufacture boron filaments that had high strength and high stiffness, but low density and, hence, low weight. During the interim, advanced boron fibers have been used as a reinforcement in resin-matrix composites. Boron aluminum has been used for tube-shaped truss members, for reinforcing space vehicle structures, and has also been considered as a fan blade material for turbofan jet engines.These shortcomings led to the development of silicon-carbide (SiC) fibers for some applications.
The principal use of boron filaments is in the form of continuous boronepoxy pre-impregnated tape, commonly known as prepreg. Usually, the resin content is about 30–35% (weight). Boron composites have been used in military aircraft, including helicopters. In addition to aircraft, boron-epoxy composites have been used in tennis, racquetball, squash, and badminton rackets, fishing rods, skis, and golf club shafts, for improving strength and stiffness.
Boron has been used in cutting and grinding tools. Boron is 30–40% harder than silicon carbide and almost twice as hard as tungsten carbide. Boron also has interesting microwave polarization properties. Research (Southern Illinois University) has shown that a single ply of boron epoxy will transmit 98.5% and reflect 0.6% of the incident microwave power when the angle between the grain and the E-field is 90°. This property has been useful in the design of spacecraft antennas and radomes.

Safety

• Symbol(GHS): GHS07
• Signal word: Warning
• Hazard statements: H302-H412
• Precautionary statements: P264-P270-P273-P301+P312-P501
• Hazard Codes: Xn,F
• Risk Statements: 22-11-63-62
• Safety Statements: 16-24/25-45-36/37/39-27-26
• RIDADR: UN 3178 4.1/PG 2
• WGK Germany: -
• RTECS: ED7350000
• TSCA: Yes
• HazardClass: 4.1
• PackingGroup: III
• HS Code: 28045000
• Hazardous Substances Data: 7440-42-8(Hazardous Substances Data)