Encyclopedia of Glass Science, Technology, History, and Culture. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Техническая литература
Год издания: 0
isbn: 9781118799499
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      (4)equation

      where x(j) and M(j) are the mole fraction and molar mass of oxide j, respectively, and ρ the density of the glass.

      As for Poisson's ratio μ, it is calculated as

      (5)equation

      4.3 Thermal Expansion Coefficient

Oxide j Increment α(j) Condition
SiO2 10.5–10·x(SiO2) x(SiO2) > 0.67
3.8 Otherwise
TiO2 10.5–15·x(SiO2) 0.5 < x(SiO2) < 0.8
ZrO2 −6.0
Al2O3 −3.0
B2O3 −1.26·φ φ < 4
−5.0 Otherwise
MgO 6.0
CaO 13.0
BaO 20.0
MnO 10.5
ZnO 5.0
PbO 13.0 x(R2O) < 0.03
13.0 (1/ψ)·∑ x(R2O) < 3
11.5 + 0.5·∑ x(R2O) Otherwise
Li2O 27.0
Na2O 41.0 in Na2O–SiO2
39.5 Otherwise
K2O 46.5 in K2O–SiO2
42.0 Otherwise

      φ = (Na2O + K2O + BaO + 0.7·CaO + 0.7·PbO + 0.3·Li2O + 0.3·MgO + 0.3·ZnO − Al2O3)/B2O3;

      ψ = ∑ (RO + R2O3 + R2O5);

      Oxide amounts to be inserted as molar fractions.

Graph depicts the change of the thermal expansion coefficient α20–300 in the base glass composition 74 SiO2 10 CaO 16 Na2O upon the replacement of x wt percent of calcia by another oxide. Graph depicts the Ternary composition diagram of the system Na2O–B2O3–SiO2 showing iso lines of the thermal expansion coefficient α20–300; base glass compositions reaching coefficient α20–300 = 4.0 ppm/K are highlighted; the further development strategy toward an industrial product is sketched in the upper right corner and indicated by the arrow.