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test and detection of cosmetics tubes for cosmetic tube manufacturer
The difference between hard glass and soft glass
by：Lisson
2021-04-07
Rigid glass (also known as high borosilicate glass) material glass SiO (about %), sodium borate (%). High temperature resistance, high pressure, corrosion resistance, high mechanical strength, good thermal conductivity, resistance to temperature changes , Operating temperature
Soft glass (also known as ordinary glass) material glass can be divided into soda lime glass (SiO, CaO, NaO) and potassium glass (SiO, CaO, KO, AlO, BO) according to the composition. In terms of corrosion resistance, hardness, In terms of transparency and devitrification, potassium glass is better than soda glass, but it is worse in terms of thermal stability. It has a low softening temperature, strong alkali resistance, and is not easy to devitrify. It is suitable for lamp flame processing, but because it cannot withstand excessive temperature differences, It is often used to make instruments that are not directly heated. Such as burettes, pipettes, measuring cylinders, etc., because their expansion coefficient is close to Pt, they can be sealed with Pt wire.
Identification method of glass tube material
Classification
Tube end color
Heating reaction
Performance characteristics
Purpose
Soft glass
Turquoise
It will soften soon after heating. If it is aluminum glass, it will turn black at the same time, and the flame of soda glass will be slightly yellow.
Soft glass contains soluble silicate, has poor chemical resistance to corrosion, has a strong adsorption force, large thermal expansion coefficient, and is easy to break due to sudden changes in temperature.
Utensils made of soft glass are generally only used for diluting acid-base solutions and titrating. Such as: volumetric flask
Hard glass
yellow or white
Heating for a short period of time does not soften, heating for a long time can be softened, and it will become hard after leaving the flame.
Rigid glass contains less soluble impurities and has a small thermal expansion coefficient, which is convenient for heat treatment.
Rigid glassware is suitable for general chemical analysis of major elements. Commonly used are borosilicate glass, such as: medical penicillin bottle
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