Coated Cerium Suboxide Particles via Flame Spray Pyrolysis
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Solution Overview
Problem
Metal oxides used in various applications, such as cosmetics and electronics, are unstable over time and prone to degradation in the presence of water, leading to a loss of desired optical properties like UV protection.
Innovation Solution
Development of coated cerium suboxide particles with a core/shell structure, where the core is cerium suboxide (CeO2-x) and the shell is composed of a compound like silicon dioxide (SiO2) or carbon, achieved through flame spray pyrolysis technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If metal oxides are used for UV protection and optical properties, then light absorption and scattering properties are improved, but stability over time and water resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining cerium suboxide core particles with silica shell particles to create a coated particle structure. This composite approach allows the cerium suboxide to provide UV protection and optical properties while the silica coating provides water resistance and stability, resolving the contradiction between optical performance and long-term stability.
Solution Approach 2:
The silica coating acts as an intermediary layer between the cerium suboxide core and the external environment (water and air). This intermediate layer protects the cerium suboxide from degradation by water while allowing the particle to maintain its optical properties, thus mediating between the need for stability and optical performance.
2Reliability
If metal oxides are coated with silica via sol-gel process, then water resistance is improved, but optical properties deteriorate
Solution Approach 1:
The patent changes the parameters of the coating process by using flame spray pyrolysis instead of sol-gel, and by controlling the coating thickness to be 1-20 nm. This parameter change allows the silica coating to provide water resistance while maintaining good optical properties, as the thin coating layer minimizes interference with light absorption and scattering.
Solution Approach 2:
The patent applies local quality by creating a thin silica coating layer (1-20 nm) that provides water resistance only where needed on the particle surface, while the bulk cerium suboxide core maintains its optical properties. This localized approach to coating ensures that water protection is achieved without compromising the overall optical performance.
3Reliability
If fluoro compounds are grafted onto metal oxides, then water resistance is improved, but environmental harm and user hazard increase
Solution Approach 1:
The patent replaces hazardous fluoro compounds with silica, which is a safe, abundant, and environmentally friendly material. This substitution eliminates the harmful effects associated with fluoro compound grafting while maintaining the desired water resistance property, effectively replacing a harmful solution with a safe alternative.
4Productivity
If known FSP processes are used to prepare metal oxide particles, then production efficiency is improved, but water resistance and stability of intermediate oxidation state oxides deteriorate
Solution Approach 1:
The patent applies preliminary action by forming the silica coating layer during the flame spray pyrolysis process itself, before the particles are exposed to water or air. This is achieved by introducing a silica-containing precursor solution that is sprayed into the flame along with the cerium precursor, allowing the coating to form in advance and provide immediate protection against water and oxidation.
Solution Approach 2:
The patent uses composite materials by combining cerium suboxide with silica in a core-shell structure, where the silica shell provides water resistance and stability to the cerium suboxide core. This composite approach maintains the production efficiency of FSP while significantly improving the stability and water resistance of the resulting particles.
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 coated cerium suboxide particles exhibit enhanced stability in water, maintain good optical properties for UV absorption and scattering, and provide effective UV screening while being environmentally friendly and suitable for use in various formulations.
Implementation Method 1
a process for preparing coated cerium oxide or suboxide particles by means of flame spray pyrolysis technology
Implementation Method 2
the liquids sprayed into the flame, on being consumed, notably emit metal oxide nanoparticles
Implementation Method 3
coated cerium suboxide particles... exhibit enhanced stability in water
Data Source
AI summary
The present invention relates to coated cerium suboxide particles, to a process for preparing coated cerium oxide or suboxide particles by means of flame spray pyrolysis technology, to the cerium oxide particles resulting from such a process, to compositions comprising such particles and also to the uses thereof.