Silicon oxide

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Silicon oxide is resistant to most acids and bases. It is only attacked by HF acid. Because it is electrical insolating, it is used in the semiconductor industry as barrier layer. Since it is transparent to light, it is used for optical purposes.

The melting point lies at 1700C. However, it is only stable in an oxygen atmosphere. In vacuum around 900C the SiO2 is converted to SiO and oxygen. The former is a gas and will cause the SiO2  sublimate.

Material  Melting point chemical stability E-module
(kg/mm
2)
thermal-expansion
coefficient
α (x 10 -6)
SiO2 1723 slightly soluble in HF, very slightly in alkali 0.5-1 0.5