Non-Oxide Ceramic Slurry Curing with Near-Infrared Up-Conversion
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Solution Overview
Problem
Non-oxide ceramics face challenges in sintering and lightweight processing, particularly in photocuring due to high refractive index and absorbance, leading to poor dispersion stability and limited curing thickness, which hinders their application in industries like aerospace and microelectronics.
Innovation Solution
A near-infrared photothermal coupling curing system is developed, combining up-conversion assisted polymerization with photothermal conversion mechanisms, using a ceramic slurry composed of non-oxide powders, photosensitive resin, monomer, photoinitiator, thermal initiator, and additives, to enhance curing efficiency through dual curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional photocuring technology is used on non-oxide ceramics, then the curing process is rapid and environmentally friendly, but the high refractive index and absorbance of non-oxide ceramics cause poor dispersion stability and limited curing layer thickness
Solution Approach 1:
The patent changes the wavelength parameter of the curing light from traditional UV/visible light to near-infrared light (700-2500 nm). This parameter change allows the light to penetrate deeper into the ceramic slurry despite the high refractive index and absorbance, thereby increasing the curing layer thickness while maintaining rapid curing speed. The near-infrared wavelength specifically addresses the optical properties of non-oxide ceramics to overcome the depth limitation.
Solution Approach 2:
The patent introduces up-conversion particles as an intermediary substance in the ceramic slurry. These particles absorb near-infrared light and convert it to higher energy photons (visible or UV range) through up-conversion. This intermediary mechanism enables the near-infrared light to initiate photopolymerization effectively, solving both the penetration depth issue and the polymerization initiation issue simultaneously.
2Adaptability or versatility
If surface oxidation of powder is employed to reduce refractive index and weaken powder light absorption, then photocuring of certain non-oxide powders becomes possible, but controlling the oxidation thickness is challenging which limits the curing thickness
Solution Approach 1:
Instead of modifying the ceramic powder surface through oxidation (traditional approach), the patent inverts the approach by modifying the light wavelength to near-infrared. This inversion allows the light to penetrate the unmodified ceramic powder directly, eliminating the need for precise oxidation thickness control while still enabling effective photocuring through the up-conversion mechanism.
3Ease of operation
If up-conversion particles are used to absorb near-infrared photons and emit high-energy photons, then photochemical reactions can be initiated at close range, but as filler content increases the extinction effects intensify leading to decreased up-conversion luminescence and polymerization efficiency
Solution Approach 1:
The patent applies local quality by creating zones of different filler concentrations within the slurry system. The up-conversion particles are distributed to provide localized light conversion where needed, while maintaining areas with lower extinction effects. This localized approach allows photochemical reactions to be initiated effectively without sacrificing overall polymerization efficiency across the entire curing depth.
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 system enables rapid and thorough curing of high solid content non-oxide ceramic slurry, resulting in high-fidelity ceramic structures with improved mechanical properties, overcoming limitations of single photocuring or thermal curing processes.
Implementation Method 1
Compared to ultraviolet and visible light, near-infrared light offers advantages such as reduced light damage, lower light scattering, and greater penetration depth
Implementation Method 2
the up-conversion particles can absorb multiple low-energy near-infrared photons and emit high-energy photons with shorter wavelengths in the ultraviolet, visible, and near-infrared range
Implementation Method 3
non-oxide ceramic powders have the unique property of photothermal conversion under near-infrared light irradiation. The excited state electrons can relax from the excited state to the ground state through non-radiative emission, generating thermal energy
Data Source
AI summary
The invention presents a near-infrared photothermal coupling curing non-oxide ceramic slurry, along with its preparation method and application. The ceramic slurry consists of various raw materials, with weight fractions as follows: non-oxide ceramic powder (40˜90 parts), photosensitive resin (0.5˜20 parts), photosensitive monomer (1˜40 parts), photoinitiator (0.25˜4 parts), thermal initiator (0.25˜4 parts), additive (0.75˜5 parts), and up-conversion luminescent material (0.5˜4 parts). The non-oxide ceramic powders can include Si3N4, TiN, BN, AlN, SiC, WC, TiC, ZrC, TiB2, and ZrB2. By combining the photochemical and photothermal dual curing system using near-infrared up-conversion, this invention addresses the issue of insufficient curing encountered in single photocuring or thermal curing processes. Moreover, by incorporating near-infrared light source-driven additive manufacturing, it enables rapid prototyping of high-solid-content non-oxide ceramic slurry, ultimately allowing for the fabrication of high-fidelity non-oxide ceramic structures.