Porous SiO2 Layer on TiO2 Substrate for Uniform Hydrophilicity
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Solution Overview
Problem
Forming a thin, porous SiO2 layer with uniform film thickness distribution on a photocatalytic TiO2 layer is challenging due to instability in SiO2 vapor deposition molecules at increased gas pressures, leading to irregularities and partial exposure of the TiO2 layer.
Innovation Solution
A photocatalytic TiO2 layer with a density of 3.33 to 3.75 g/cm3 is formed, allowing for stable vapor deposition of SiO2 at low gas pressure, resulting in a thin, uniform porous SiO2 layer that covers the entire TiO2 layer, preventing exposure and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas pressure is increased during SiO2 vapor deposition, then deposition speed increases, but SiO2 vapor deposition molecules become unstable causing irregular film thickness distribution
Solution Approach 1:
The patent changes the gas pressure parameter during vapor deposition from high pressure to low pressure (0.01 to 0.1 Pa) to stabilize SiO2 vapor deposition molecules. This parameter change resolves the contradiction by prioritizing molecular stability and film uniformity over deposition speed, allowing controlled formation of uniformly thick porous SiO2 layers
Solution Approach 2:
The patent uses porous SiO2 layer formation through controlled vapor deposition at low pressure. The porous structure enables the layer to be both thin (10-50 nm) and uniform, while the low pressure deposition ensures stable molecular flight and consistent film thickness distribution across the substrate surface
2Manufacturing precision
If a thin porous SiO2 layer is formed to ensure uniform hydrophilicity, then the layer must be no more than 50 nm thick, but it becomes difficult to achieve complete coverage of the TiO2 layer
Solution Approach 1:
The patent controls the vapor deposition parameters (low gas pressure of 0.01 to 0.1 Pa, substrate temperature of 200 to 400°C) to enable formation of thin porous SiO2 layers (10-50 nm) with complete and uniform coverage. These parameter changes ensure that even at minimal thickness, the layer achieves full coverage without exposing the underlying TiO2 layer
Solution Approach 2:
The patent performs preliminary preparation of the TiO2 layer surface and controls deposition conditions in advance to ensure that the thin porous SiO2 layer will achieve complete coverage. By pre-establishing optimal deposition parameters and surface conditions, the thin layer can be formed with sufficient coverage reliability
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
This approach enables easy formation of a hydrophilic member with uniform hydrophilicity, improved scratch resistance, and enhanced acid resistance, ensuring effective photocatalysis and durability of the porous SiO2 layer.
Implementation Method 1
decomposes organic matter and the like adhered to the porous SiO2 layer by means of photocatalysis provided by the photocatalytic TiO2 layer below the porous SiO2 layer
Implementation Method 2
it is necessary to vapor-deposit SiO2 with an increased gas pressure (partial pressure of oxygen gas) in a vapor deposition atmosphere
Implementation Method 3
time from a state in which hydrophilicity had been lost due to adherence of organic matter to a surface thereof to recovery of hydrophilicity due to ultraviolet irradiation
Data Source
AI summary
In a hydrophilic member including a structure in which a photocatalytic TiO2 layer and a porous SiO2 layer are stacked on a surface of a base material, easy forming of the porous SiO2 layer so as to be thin and have a uniform film thickness distribution that enables the porous SiO2 layer to cover an entire surface of the photocatalytic TiO2 layer, and enhancement in durability of the porous SiO2 layer are enabled. A photocatalytic TiO2 layer is formed so as to have a density of 3.33 to 3.75 g/cm3 (preferably 3.47 to 3.72 g/cm3, more preferably 3.54 to 3.68 g/cm3) on a surface of a base material. As an outermost surface layer, a porous SiO2 layer is formed on the photocatalytic TiO2 layer in such a manner that the porous SiO2 layer has a film thickness of no less than 10 nm and no more than 50 nm.