Physical Properties of Borosilicate Glass PDF

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Lab Work Borosilicate Glass...

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Physical Properties of Borosilicate Glass 3.3 Borosilicate glass 3.3 differs from other materials used in construction not only because of its virtually universal resistance to Mean linear thermal expansion coefficient

a 20/300

=

(3,3 ± 0,1) x 10-6 K-1

Mean thermal conductivity between 20 and 200°C

l 20/200

=

1,2 W m-1 K-1

Mean specific heat capacity between 20 and 100°C

Cp 20/100

=

0,8 kJ kg-1 K-1

Mean specific heat capacity between 20 and 200°C

Cp 20/200

=

0,9 kJ kg-1 K-1

=

2,23 kg dm-³

Density at 20°C

The common type of borosilicate glass used for laboratory glassware has a very low thermal expansion coefficient (3.3 × 10−6 K−1),[3] about one-third that of ordinary soda-lime glass. This reduces material stresses caused by temperature gradients, which makes borosilicate a more suitable type of glass for certain applications (see below). Borosilicate glass is a lowcost compromise. While more resistant to thermal shock than other types of glass, borosilicate glass can still crack or shatter when subjected to rapid or uneven temperature variations. Among the characteristic properties of this glass family are: 

Different borosilicat glasses cover a wide range of different thermal expansions enabeling direct seals with various metals and alloys like [molybdum] glass with a CTE of 4,6, tungsten with a CTE around 4,0 and Kovar with a CTE around 5,0 because of the matched CTE with the sealing partner



Allowing high maximum temperatures of typically about 500 °C



Showing an extremely high chemical resistance in corrosive environments. Norm tests for example for acid resistancecreate extrem conditions and reveal very low impacts on glass

The softening point (temperature at which viscosity is approximately 107.6 poise) of type 7740 Pyrex is 820 °C (1,510 °F).[4] Borosilicate glass is less dense (about 2.23 g/cm3) than typical soda-lime glass due to the low atomic mass of boron. The temperature differential that borosilicate glass can withstand before fracturing is about 165 °C (329 °F). This compares well with soda lime glass, which can withstand only a 37 °C (99 °F) change in temperature and is why typical kitchenware made from traditional sodalime glass will shatter if a vessel containing boiling water is placed on ice, but Pyrex or other borosilicate glass laboratory will not.[5] Optically, borosilicate glasses are crown glasses with low dispersion (Abbe numbers around 65) and relatively low refractive indices (1.51–1.54 across the visible range).

Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very lowcoefficients of thermal expansion (~3 × 10−6 K−1 at 20 °C), making them resistant tothermal shock, more so than any other common glass. Such glass is less subject tothermal stress and is commonly used for the construction of reagent bottles. Borosilicate glass is sold under such trade names as Borcam, Borosil, DURAN, Suprax, Simax, BSA 60, BSC 51 (By NIPRO), Heatex, Endural, Schott, Refmex,Kimble, and some (but not all) items sold under the trade name Pyrex. Coeff. of Exp.

32.5 x 10-7cm/cm/°C

Strain Point

510°C

Anneal Point

560°C

Soften Point

821°C

Density

2.23 g/cm3

Youngs Mod.

6.4 x 103 Kg/mm2

Refract. Index

1.474 @ Sodium D Line

Temp. Limits Max. Thermal Shock

490°C (Extreme Service) 230°C (Normal Service) 160°C

Physical properties of borosilicate glass Borosilicate glass is a type of glass which compromise of silica and boron trioxide as the main components. Below are some of the physical properties of borosilicate glass; 

It has a very low thermal expansion coefficient   

−6 −1 ~ 3 × 10 K at 20 °C Resists thermal shock due to changes of temperature. Thus, no need of extreme measures to compensate thermal expansion. Reduces thermal stresses and is commonly used as the reagent bottles....