Glass linear expansion

These techniques help in providing the following information specific heat, enthalpy changes, heat of transformation, crystallinity, melting behavior, evaporation, sublimation, glass transition, thermal decomposition, depolymerization, thermal stability, content analysis, chemical reactions/polymerization linear expansion, coefficient, and Young s modulus, etc. 

Phoenix, also, is a borosilicate glass made by the British Heat Resisting Glass Co. The linear expansion coefficient (50-450°Q is 3-24 X 10" . Tubing and rod are supplied in a wide range of sizes. The tubing is made with either standard wall or heavy wall. 

Laboratory glassware made from this glass is available. It is a borosilicate glass manufactured by Wood Bros. Glass Co. The linear expansion coefficient (0-400°Q is 3-2 x 10 . 

This is another borosilicate glass, and was developed to make strain-free seals with timgsten. It is made by the General Electric Co., and often described as GEC W.l, or simply as W.l. The linear expansion coefficient (20-350°C) is 3-75 x 10 . 

Made by Plowden Thompson Ltd. Dial 36 is a borosilicate glass for sealing to timgsten. The linear expansion coefficient (20-300°Q is 3-6 X 10 . 

BTH No. 12 is a lead glass for lamp and valve manufacture, made by the British Thomson-Houston Co. The linear expansion coefficient (50-400°Q is 9-1 X 10- . 

This is made by the General Electric Co., and is used for medical ampoules. It loses very little alkali to aqueous solutions. The linear expansion coefficient is 7-3 x 10 from 20 to 350°C. This is intermediate between the soft and hard glasses, and M.6. is sometimes used in graded seals. 

This glass, made by the General Electric Co., is similar to white neutral above, but is coloured amber by addition of iron and manganese. The linear expansion coefficient is 7-5 x 10" from 20 to 350°C. It is useful for ampoules when the contents need protection from ultra-violet radiation. 

Lemington H.26X., made by the General Electric Co., is a very hard borosilicate glass of high softening temperature. Tte Mg point is 780°C. It is used in high pressure mercury vapour lamps. The linear expansion coefficient is 4-6 x 10 from 20 to 580°C. Sodium and potassiiun are absent and alumina is present in quantity in this glass. 

A borosilicate glass for sealing to alloys of the Kovar type (p. Ill) l Clso seals to some electrical porcelains. It is made by the British phomson Houston Co., and is often referred to as BTH C,40 or as The linear expansion coefficient is 4-85 x 10 from 50 to... 

Pids is a soda glass for sealing to platinum, and is made by Plowden b Thompson Ltd. The linear expansion coefficient (20-300°C) is pi K 10-. ... 

Thermal Expansion. Most manufacturers literature (87,119,136—138) quotes a linear expansion coefficient within the 0—300°C range of 5.4 x 10"7 to 5.6 x 10 7 /°C. The effect of thermal history on low temperature expansion of Homosil (Heraeus Schott Quarzschmelze GmbH) and Osram s vitreous silicas is shown in Figure 4. The 1000, 1300, and 1720°C curves are for samples that were held at these temperatures until equilibrium density was achieved and then quenched in water. The effect of temperature on linear expansion of vitreous silica is compared with that of typical soda—lime and borosilicate glasses in Figure 5. The low thermal expansion of vitreous silica is the main reason that it has a high thermal shock resistance compared to other glasses. 

As shown in Table 13.2, the heat deflection temperature of ABS is increased by the incorporation of fibrous glass. The copolymer reinforced with 20% fibrous glass has a lower coefficient of linear expansion (2.0 X 10 5 on/cm C) and higher compressive, flexural, and tensile strengths than unfilled SAN. These improvements are related to the amount of fibrous glass present in the composite. 

With the method used here, the specimen is free to expand in only one direction, and this means that only a linear expansion can be determined. This is the same as volumetric expansion. If the system is above its glass temperature, 7g,... 

The coefficient of linear expansion can be measured as an average over tens of °C to reasonable precision using a precision cathetometer. Most contact methods of measuring length are not suitable because of the low stiffness of rubber and, for the same reason, it is often necessary to support the test piece in a horizontal position. A convenient procedure is to lay a test piece on smooth rollers in a glass-sided bath, but it must be emphasised that only moderate precision can normally be obtained, unless an extremely sensitive optical measuring device is employed, and friction can never be eliminated. 

Does the coefficient of linear expansion of a polymer increase or decrease upon the addition of glass fibers ... 

Fig. 1.3 Step process for using linear expansion to separate glass types.

The densities (d), refractive indices at sodium D-line (nD) and linear expansion coefficients (a) are also given in Table 1, for information. One should remark the higher refractive indices measured for glasses containing highly polarizable elements such as Pb or Cl. 

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