Opaque Quartz Glass Bubble Control
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Solution Overview
Problem
Existing methods for manufacturing opaque quartz glass ingots with spherical bubbles face challenges in achieving a balance between mechanical strength, surface roughness, and light reflectance, with amorphous bubble methods resulting in low mechanical strength and high surface roughness, while spherical bubble methods struggle with large size limitations and uneven surfaces.
Innovation Solution
Control the mean diameter of bubbles in opaque quartz glass to be less than 1 μm, using a manufacturing process involving silica powder slurry wet pulverization, spray dry granulation, and press-molding to achieve a density of 2.16 to 2.19 g/cm3, whiteness of 90% or more, and bending strength of 75 MPa or more, with surface roughness Ra of 0.5 μm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amorphous bubble manufacturing method is used, then average particle size of bubbles is reduced and baked surface smoothness is improved, but mechanical strength is lowered due to stress concentration at bubble edges
Solution Approach 1:
The patent transforms the bubble shape from amorphous (irregular) to spherical, eliminating corners and edges where stress would concentrate. The spherical bubbles are formed by controlling the silica powder particle size distribution and firing conditions, creating a curved surface that distributes stress uniformly throughout the structure, thereby maintaining surface smoothness while significantly improving mechanical strength.
2Strength
If spherical bubble manufacturing method is used, then mechanical strength is improved due to no stress concentration, but average bubble diameter cannot be reduced and baked surface becomes rough
Solution Approach 1:
The patent changes the particle size parameters of the silica powder used in the slurry, specifically controlling the average particle size to 2-8 μm and standard deviation to 3-7 μm. This parameter control during the slurry preparation stage enables formation of uniform spherical bubbles with controlled diameter (0.1-1.0 μm) while maintaining surface smoothness, resolving the contradiction between strength and surface quality.
Solution Approach 2:
The patent performs preliminary classification and size control of silica powder particles before slurry formation. By pre-sorting the powder particles into a specific size range (2-8 μm average, 3-7 μm standard deviation), the foundation is set for forming uniform spherical bubbles during firing, preventing surface roughness and controlling bubble diameter from the outset.
3Volume of stationary object
If large sized opaque quartz glass ingot is manufactured, then application range is expanded, but bubble diameter increases reducing whiteness and reflectance
Solution Approach 1:
The patent maintains the critical parameter of small bubble diameter (0.1-1.0 μm) even in large sized ingots by controlling the silica powder particle size distribution (2-8 μm average, 3-7 μm standard deviation) and optimizing firing conditions. This parameter control ensures that regardless of ingot size, the bubbles remain small enough to maintain high whiteness (90% or more) and light reflectance (85% or more), enabling large sized ingots for semiconductor equipment without sacrificing optical properties.
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
The resulting opaque quartz glass exhibits enhanced heat ray blocking, light blocking properties, and improved mechanical strength, making it suitable for semiconductor manufacturing and optical applications with a smooth, high-quality surface.
Implementation Method 1
a silica powder slurry having silica powder concentration of 45 to 75 wt % is subjected to wet pulverization by applying one or a combination of two or more methods selected from beads mill pulverization, ball mill pulverization, vibration mill pulverization and attritor pulverization
Implementation Method 2
the slurry is subjected to spray dry granulation for forming substantially spherical granulated silica particles
Implementation Method 3
the slurry is subjected to spray dry granulation for forming substantially spherical granulated silica particles
Implementation Method 4
the prepared slurry is subjected to spray drying to obtain granulated silica particles and the granulated silica particles are press-molded and fired
Implementation Method 5
the granulated silica particles are press-molded and fired
Data Source
AI summary
A large sized opaque quartz glass ingot having an excellent heat ray shielding property, an outstanding light blocking property, high mechanical strength and small roughness of a baked finished smooth surface.The shape of bubbles inside the quartz glass are almost complete spheres and the average particle size of the bubbles is 1 μm or less, such that the strength of the opaque quartz glass ingot is increased as the stress concentration at the edges of the bubbles is eliminated and an increase of surface roughness caused by baking is alleviated.