SiO2 Granule Sintering for Bubble-Free Quartz Glass
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Solution Overview
Problem
The production of transparent quartz glass from open-pored SiO2 granules is challenging due to bubble formation and non-uniform temperature distribution during melting, leading to inhomogeneous properties and high energy consumption.
Innovation Solution
Optimizing the sintering atmosphere, temperature, and duration to achieve SiO2 granules with a bulk density of 0.9 kg/l to 1.3 kg/l and specific BET surface area of 1 m^2/g to 25 m^2/g, while maintaining infrared transparency, allowing for easier melting and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If open-pored SiO2 granules are used for melting, then the production process can be simplified and energy consumption reduced, but bubble formation occurs and temperature distribution becomes non-uniform
Solution Approach 1:
The patent applies parameter changes by optimizing the sintering atmosphere composition (oxygen partial pressure, gas flow rate), sintering temperature (1000-1500°C), and sintering duration to control the pore structure and density of SiO2 granules. These parameter adjustments enable the granules to achieve optimal thermal conductivity and bubble-free melting characteristics, resolving the contradiction between energy efficiency and product homogeneity.
Solution Approach 2:
The patent implements preliminary action by performing sintering treatment on SiO2 granules before the melting process. This pre-treatment densifies the granules, controls pore formation, and prepares them for uniform melting, preventing bubble formation during the subsequent melting step and ensuring homogeneous product properties.
2Quantity of substance
If sintering temperature is increased to densify granules, then bulk density increases and melting becomes easier, but energy consumption increases
Solution Approach 1:
The patent utilizes parameter changes by optimizing the sintering temperature range (1000-1500°C) and atmosphere composition to achieve the desired bulk density (0.9-1.3 kg/l) with minimal energy input. The controlled atmosphere conditions enable densification at lower temperatures than conventional methods, reducing energy consumption while maintaining granule density.
Solution Approach 2:
The patent applies inert atmosphere by using controlled gas environments (oxygen partial pressure, gas flow rate) during sintering. This protects the SiO2 granules from unwanted oxidation, enables controlled densification, and reduces the energy required for temperature increase, achieving high bulk density with lower energy consumption.
3Use of energy by stationary object
If granules are highly dense, then melting is easier and energy consumption is reduced, but infrared transparency is compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling sintering atmosphere composition, temperature, and duration to achieve an optimal balance between density and infrared transparency. The controlled pore structure maintained during sintering allows the granules to remain sufficiently transparent for infrared radiation while achieving adequate density for easy melting and low energy consumption.
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 enables the production of high-quality, bubble-free transparent quartz glass with reduced energy and material expenditure, facilitating the melting process and improving the homogeneity of the final product.
Implementation Method 1
Sintering of the open-pore SiO2 granule by heating in a sintering atmosphere at a sintering temperature and for a sintering duration to form a densified SiO2 granule
Implementation Method 2
Melting of the densified SiO2 granule at a melting temperature to form the component made of synthetic quartz glass
Implementation Method 3
at a wavelength of 1700 nm, they exhibit a material-specific infrared transmission T1700 - measured using a measurement method defined in the description - which is in the range of 50 to 95% of the infrared transmission T1700 of a quartz glass granule
Data Source
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AI summary
A known process for producing opaque, synthetic quartz glass by melting SiO2 granules comprises the following steps: synthesis of amorphous SiO2 primary particles, granulation of the amorphous SiO2 primary particles to form open-pored SiO2 granules, sintering of the open-pored SiO2 granules by heating in a sintering atmosphere at a sintering temperature and for a specified sintering time to form densified SiO2 granules, and melting of the densified SiO2 granules at a melting temperature to form synthetic quartz glass. The aim here is to describe a process that enables the cost-effective production of bubble-free, transparent quartz glass components despite the use of still open-pored SiO2 granules.According to the invention, it is proposed that the sintering atmosphere, sintering temperature and sintering duration during sintering according to process step (c) are adjusted such that the densified SiO2 granules remain open-pored on the one hand and exhibit a material-specific infrared transmission T1700 at a wavelength of 1700 nm, which is in the range of 50 to 95% of the infrared transmission T1700 of a quartz glass granule of the same material.