Refractories specific gravity

Flint is an important form of silica, used in the pottery and refractories industries. It is believed to consist of small crystals of quartz, bound together by molecules of water and their presence probably accounts for the specific gravity being about 2.62, slightly less than that of quartz. 

Zirconia occurs as the minerals zircite and baddeleyite, in Brazil and Ceylon. Pure zirconia has a specific gravity of 6.3, and is insoluble in water but soluble in sulphuric acid and hydrofluoric acid. It has a very high melting-point (about 2700°C) and is therefore used as a refractory material, although its cost prevents its... 

The chief source of beryllium oxide is the mineral beryl, or beryllium aluminium silicate, 3Be0.Al203.6Si02, which occurs in Argentina, Brazil and India. When pure, beryllium oxide has a specific gravity of 3.0, and is almost insoluble in water it is soluble in sulphuric acid and in fused alkalis. It has been used as a refractory (melting point over 2500°C) but its toxicity has restricted its use. 

Resistant to high temperature, heavy load, fluxes and corrosive fluids like slag are the important properties of refractories. Strength and specific gravity are some other important properties. 

ASTM. 2000. Standard test methods for apparent porosity, liquid absorption, apparent specific gravity, and bulk density of refractory shapes by vacuum pressure. ASTM Stand. (C830). 

ASTM C-135 True specific gravity of refractory materials by water immersion... 

Rees-Hugill Flask. A 250 ml flask, with a neck graduated directly in specific gravity units, designed expressly for the determination of the specific gravity of silica and other refractories. It was introduced by W. Hugill and W. J. Rees (Trans. Brit. Ceram. Soc., 24,70,1925) and has since become the subject of a British Standard (B.S. 2701). 

True Specific Gravity. The ratio of the mass of a material to the mass of a quantity of water that, at 4°C, has a volume equal to the true solid VOLUME of the material at the temperature of measurement. ASTM C604 specifies a gas-comparison pycnometer test, and C135 a water immersion test for refractories. 

Chapters I-V of the reference book give information of a general character on refractory compounds, data on their crystal structure, specific gravity, thermochemical, thermal, electrical and magnetic, optical, mechanical, chemical, and refractory properties. 

SrBe Refractoriness, low specific gravity, low work factor in thermionic emission In the composition of heat-resistant alloys, in the cathodes of electronic devices [25] 1951... 

ScBj Low specific gravity, refractoriness In the composition of light, heat-resistant alloys [694] 1960... 

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