Ozone Dehydration for Synthetic Quartz Glass Hydroxyl Control
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Solution Overview
Problem
Existing methods for producing synthetic quartz glass struggle to reliably and reproducibly achieve low hydroxyl group content and low chlorine content, which are crucial for UV radiation resistance, as chlorine can introduce defects and compaction issues.
Innovation Solution
A dehydration treatment using ozone as the reaction gas at temperatures between 1200°C and 1400°C, without halogens, effectively removes hydroxyl groups and avoids chlorine residues, ensuring a predetermined hydroxyl group content and high UV radiation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chlorine-containing atmosphere is used for dehydration treatment to remove hydroxyl groups, then hydroxyl group content is reduced, but chlorine content increases which deteriorates UV radiation resistance
Solution Approach 1:
The patent changes the chemical composition parameter of the drying atmosphere from chlorine-containing to ozone-containing gas. This parameter change allows effective hydroxyl group removal through ozone oxidation while avoiding chlorine contamination that would harm UV radiation resistance. The ozone concentration is specifically controlled at 5-20% by volume to achieve optimal dehydration效果.
Solution Approach 2:
The patent converts the potentially harmful effect of oxygen (which can cause re-oxidation) into a beneficial effect by using ozone, a highly reactive oxygen allotrope. Ozone provides strong oxidizing power for hydroxyl group removal while decomposing into oxygen that saturates oxygen defects, thereby preventing re-formation of hydroxyl groups and improving UV radiation resistance.
2Quantity of substance
If dehydration treatment is performed at high temperature to remove hydroxyl groups, then hydroxyl group content is reduced, but process complexity and time increase
Solution Approach 1:
The patent employs ozone, a strong oxidant, to accelerate the dehydration process. Ozone's high reactivity allows effective hydroxyl group removal at lower temperatures and shorter times compared to conventional thermal dehydration. The strong oxidizing power of ozone enables rapid conversion of hydroxyl groups without requiring prolonged high-temperature treatment.
Solution Approach 2:
The patent changes the chemical environment parameter by introducing ozone into the drying atmosphere, which fundamentally alters the dehydration mechanism from purely thermal to chemically-assisted oxidation. This parameter change reduces both temperature and time requirements for achieving the desired hydroxyl group content.
3Quantity of substance
If multiple treatment steps are used to remove both hydroxyl groups and chlorine, then purity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts and eliminates the chlorine-containing dehydration step from the manufacturing process entirely. By using ozone instead of chlorine-containing gases, the process achieves hydroxyl group removal without introducing chlorine contamination, thereby eliminating the need for subsequent chlorine removal steps and simplifying the overall manufacturing process.
Solution Approach 2:
Ozone serves multiple functions in a single treatment step: it removes hydroxyl groups through oxidation, saturates oxygen defects to prevent hydroxyl group re-formation, and avoids introducing harmful contaminants. This multi-functionality replaces what would otherwise require multiple separate treatment steps, thereby reducing manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method ensures reproducible production of synthetic quartz glass with low hydroxyl and chlorine content, preventing UV-induced birefringence and compaction, and eliminates the need for time-consuming chlorine removal processes, resulting in high UV radiation resistance and defect-free glass networks.
Implementation Method 1
the dehydration treatment according to method step (b) comprises a drying phase during which ozone is used as the reaction gas
Implementation Method 2
the SiO2 soot body is vitrified into a body consisting of the synthetic quartz glass
Data Source
AI summary
A known method for producing synthetic quartz glass with a predetermined hydroxyl group content comprises the following steps: a porous SiO2 soot body is produced by flame hydrolysis or oxidation of a silicon-containing start compound and by layerwise deposition of SiO2 particles on a rotating support; the soot body is subjected to a dehydration treatment in a reaction gas-containing drying atmosphere at a drying temperature for removing hydroxyl groups; and the SiO2 soot body is vitrified into a body consisting of the synthetic quartz glass. Starting from this, and in order to permit a reproducible and reliable manufacture of synthetic, UV-radiation resistant quartz glass with predetermined hydroxyl group content and low chlorine content, it is suggested according to the invention that the dehydration treatment according to method step (b) comprises a drying phase during which ozone is used as the reaction gas, whereby the ozone content of the drying atmosphere is between 0.5% by vol. and 10% by vol. and the drying temperature is chosen in the range between 1200° C. and 1400° C., and whereby no halogens are supplied to the drying atmosphere.