Calcium Fluoride Polycrystal Sintering for High Optical Transmittance
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Solution Overview
Problem
Existing calcium fluoride sintered bodies have low transmittance compared to single crystals, limiting their use as optical members.
Innovation Solution
A production method involving the generation of calcium fluoride particles through a dispersion liquid reaction, followed by mixing with hydrofluoric acid, separation, molding, and sintering in an inert atmosphere to produce a polycrystalline substance with high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hot pressing method is used to produce calcium fluoride sintered body, then manufacturing process is simple, but transmittance is low
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific amounts of calcium oxide (0.1-5 wt%) and calcium hydroxide (0.1-5 wt%) as sintering aids, and controls particle size distribution (D50: 1-10 μm, D90: 20 μm or less). These parameter changes enable achieving 98% or more transmittance at 550 nm while maintaining manufacturing feasibility through conventional sintering processes.
2Reliability
If single crystal calcium fluoride is used, then transmittance is high, but manufacturing complexity and cost increase
Solution Approach 1:
The invention uses polycrystalline calcium fluoride particles with controlled size distribution and specific sintering aids instead of expensive single crystals. This approach achieves comparable optical transmittance (98% or more at 550 nm) through a simpler, more cost-effective sintering process, effectively replacing high-cost single crystal materials with economical polycrystalline alternatives.
3Reliability
If particle size is reduced to increase density, then transmittance improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention applies different particle size specifications to different aspects: D50 (median diameter) is controlled at 1-10 μm for optimal packing and density, while D90 (90th percentile) is limited to 20 μm or less to ensure uniformity. This localized quality control approach achieves high transmittance without requiring excessively tight precision across the entire particle size distribution.
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 method achieves a calcium fluoride sintered body with internal transmittance of 98% or more for wavelengths up to 550 nm, and 90% or more for wavelengths between 380 nm to 780 nm, with optical strain reduced to 25 nm/cm or less.
Implementation Method 1
a generation step of generating a dispersion liquid containing calcium fluoride particles by reacting a calcium compound and a fluorine compound in a solution
Implementation Method 2
a sintering step of sintering the compact in an inert atmosphere to generate a polycrystalline substance
Data Source
AI summary
A calcium fluoride polycrystalline substance, in which the internal transmittance of light having a wavelength of 550 nm per thickness of 10 mm is 98% or more.