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Boric Oxide

Alternate Names: Anhydrous Boric Acid, B2O3

Oxide Analysis Formula
B2O3 100.00% 1.00
Oxide Weight 69.60
Formula Weight 69.60


A hard glassy material, granular in texture. Exposed to the atmosphere it slowly absorbs water, reverting to boric acid. It is soluble in water but at a much slower rate than boric acid. Approximately 56.3 kg of boric oxide are the chemical equivalent of 100 kg of boric acid. Boric oxide is used where B2O3 is required without the presence of sodium or calcium and/or where water would be detrimental to the process.

Specialty ceramics: Boric oxide is used to produce various types of high strength and heat-resistant ceramic products such as boron carbide, boron nitride, titanium and zirconium diborides, as well as elemental boron.

Refractories: It is used in the manufacture of chemically bonded firebricks and castables which require resistance to high temperature, abrasion and corrosion. Boric oxide is used as a binder for magnesia-based refractory bricks and as a stabilizer for dolomite refractory bricks commonly used in steel smelting furnaces.

Glazes, frits and enamels: Suppliers speak of boric oxide as increasing strength, scratch resistance, and chemical resistance of ceramic wares such as wall and floor tiles, tableware and porcelain and of enameled appliances, however they do not say compared to what.

Related Information


Boric Oxide Data Sheet
Materials Anhydrous Borax
A white, odorless product crystalline granular by dehydrating Borax to remove the crystal bound water.
Materials Borax Pentahydrate
Materials Borax Decahydrate
Materials Boric Acid
Materials Calcined Dolomite
Typecodes Flux Source
Materials that source Na2O, K2O, Li2O, CaO, MgO and other fluxes but are not feldspars or frits. Remember that materials can be flux sources but also perform many other roles. For example, talc is a flux in high temperature glazes, but a matting agent in low temperatures ones. It can also be a flux, a filler and an expansion increaser in bodies.
Oxides B2O3 - Boric Oxide
Minerals Borate Minerals
The major borate minerals are Colemanite and Ulexite. The geology required for borates is found in v


Decomposition Temperature 185C
Frit Softening Point 577C
Density (Specific Gravity) 1.5-1.75
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