Titanium Oxide Coating Crystallization via Carbon Protection
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Solution Overview
Problem
Existing processes for depositing titanium oxide thin layers on glass substrates, such as the magnetron process, often result in amorphous or nano-crystallized layers due to low substrate temperatures, which limits the self-cleaning power of the materials, and high-temperature heat treatments can lead to inconsistent results due to variations in treatment conditions.
Innovation Solution
A process involving the deposition of a temporary inorganic carbon-based protective layer on top of the titanium oxide layer, followed by a heat treatment above 350°C, preferably with quenching or long-term annealing, to promote homogeneous crystallization and enhance self-cleaning properties, while the carbon layer is partially or completely removed during treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the magnetron process is used to deposit titanium oxide thin films on glass substrates, then the deposition efficiency is high and the process is suitable for industrial scale, but the substrate temperature remains low (ambient to less than 80°C) which prevents sufficient crystal growth resulting in amorphous or nano-crystallized layers with poor self-cleaning properties
Solution Approach 1:
A temporary carbon-based protective layer is deposited on the titanium oxide layer before heat treatment. This preliminary action prepares the structure for subsequent high-temperature treatment by protecting the substrate from mechanical damage and chemical pollution during storage and transport, while allowing the titanium oxide layer to crystallize properly when heated above 350°C
Solution Approach 2:
The process changes the temperature parameter from low (ambient to <80°C) during deposition to high (>350°C, preferably >400°C or >500°C) during heat treatment. This parameter change enables sufficient crystal growth and grain size development in the titanium oxide layer, transforming it from amorphous/nano-crystallized to a state with excellent self-cleaning properties
2Reliability
If high-temperature heat treatment is applied to crystallize the titanium oxide layer, then the crystal growth and grain size increase improving self-cleaning properties, but the results are inconsistent due to variations in heat treatment conditions and the substrate is exposed to mechanical damage and chemical pollution during storage and transport
Solution Approach 1:
A temporary carbon-based protective layer is introduced as an intermediary between the substrate and the external environment. This layer protects the substrate from mechanical damage (scratches, breaks) and chemical pollution during storage and transport before heat treatment, and is subsequently removed during the heat treatment process above 350°C
Solution Approach 2:
The temporary protective layer is deposited beforehand to cushion and protect the substrate against potential mechanical damage and chemical pollution during handling, storage, and transport. This preliminary protection ensures the substrate remains intact and uncontaminated until the heat treatment process
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 process achieves high self-cleaning power with consistent photocatalytic and superhydrophilic properties, independent of heat treatment conditions, and protects the substrate from mechanical alterations and chemical pollution during storage and transport.
Implementation Method 1
The temporary protective layer based on carbon, deposited on the thin layer based on titanium oxide, promotes, during heat treatment, the crystallization of said thin layer based on titanium oxide
Implementation Method 2
heat treatment, at a temperature above 350°C, preferably 400°C or even 500°C, of the material
Implementation Method 3
The temporary protective layer based on carbon, deposited on the thin layer based on titanium oxide, promotes, during heat treatment, the crystallization of said thin layer based on titanium oxide
Implementation Method 4
a plasma is created under high vacuum near a target containing the chemical elements to be deposited. The active species in the plasma, by bombarding the target, detach these elements, which are then deposited onto the substrate, forming the desired thin film
Data Source
AI summary
The invention concerns a method for obtaining a material comprising a substrate and at least one thin layer made from titanium oxide and deposited on a first face of said substrate, said method comprising the following steps: - depositing at least said one thin layer made from titanium oxide, - depositing, on top of said thin layer made from titanium oxide, an inorganic temporary protection layer made from carbon, - subjecting the material to heat treatment at a temperature higher than 350 °C.