Silica Ceramic Laser Sintering with Cristobalite Heat Treatment
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Solution Overview
Problem
Existing additive manufacturing technologies for silica-based ceramics face challenges in achieving high molding accuracy and mechanical strength due to the high viscosity of silica-based materials, rapid cooling leading to amorphous structures, and the formation of cracks during laser irradiation.
Innovation Solution
A method involving the use of a powder containing an absorber and silicon dioxide as main components, followed by laser irradiation and heating at specific temperatures to convert amorphous silica to cristobalite, and applying a metal component-containing liquid to repair cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silica-based material is used as molding powder in direct molding system, then molding accuracy is improved, but mechanical strength becomes insufficient due to amorphous structure formation
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate after laser irradiation. Specifically, the cooling rate is adjusted to be within a predetermined range (e.g., 10^3 to 10^6 K/s) to prevent excessive rapid cooling that would form amorphous structures. This parameter control enables the formation of crystalline structures with higher mechanical strength while maintaining molding accuracy.
Solution Approach 2:
The patent employs periodic action through multi-stage heating and cooling cycles. After laser irradiation, the material undergoes controlled cooling followed by heat treatment cycles that promote crystallization. This periodic thermal processing transforms the amorphous structure into a crystalline structure, improving mechanical strength while preserving the molded shape.
2Ease of manufacture
If laser irradiation is applied to silica-based material, then melting and solidification is achieved, but cracks are generated due to rapid cooling
Solution Approach 1:
The patent applies beforehand cushioning by introducing a heating step after laser irradiation and solidification. This subsequent heating treatment compensates for the thermal stress and rapid cooling effects that cause cracks. By providing controlled heat after the harmful rapid cooling, the patent prevents crack formation and improves the reliability of the molded article.
3Manufacturing precision
If absorber is added to raw material powder, then light diffusion is prevented and molding accuracy is improved, but mechanical strength may be affected
Solution Approach 1:
The patent applies parameter changes by optimizing the composition ratio of the absorber in the raw material powder. The absorber content is controlled within specific ranges to ensure sufficient light absorption for accurate molding while maintaining the mechanical strength of the final product. This balanced composition control resolves the contradiction between molding accuracy and mechanical strength.
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 results in a silica-based ceramic article with improved mechanical strength and reduced cracks, maintaining high molding accuracy and suitability for applications like casting cores.
Implementation Method 1
an absorber that absorbs light having a predetermined wavelength
Implementation Method 2
irradiating the powder with laser including light having a predetermined wavelength
Implementation Method 3
melted by laser beam irradiation is solidified by rapid cooling from the circumference
Implementation Method 4
the solidified portion is mostly amorphous due to rapid cooling at a high temperature lowering rate
Implementation Method 5
heating a shaped object formed by repeating the steps (i) and (ii) at 1470° C. or more and less than 1730° C.
Implementation Method 6
convert amorphous silica to cristobalite
Data Source
AI summary
(i) a step of disposing a powder that includes an absorber absorbing light of a wavelength included in a laser beam to be irradiated and silicon dioxide as a main component; (ii) a step of sintering or melting and solidifying the powder by irradiating the powder with a laser beam; and (iii) a step of heat-treating a shaped object formed by repeating the steps (i) and (ii) at 1470° C. or more and less than 1730° C.