TiOxNy Coating Stress Reduction via Flash Lamp Conversion
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Solution Overview
Problem
Existing titanium oxide (TiOx) coatings in low-maintenance glass often develop high tensile stresses and microscopic cracks during thermal activation, compromising their integrity and functionality.
Innovation Solution
A method involving the formation of an intermediate TiOxNy layer, which is converted into a stress-free or slightly compressively stressed TiOx layer using electromagnetic radiation, allowing for controlled heating to 500-600 degrees C without significantly heating the substrate, thereby reducing stress and crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal activation is used to convert TiOx to anatase phase, then photocatalytic properties are improved, but tensile stress and crack formation increase
Solution Approach 1:
The patent changes the thermal activation parameters by using rapid heating to extremely high temperatures (2000-4000°C) for very short durations (microseconds to seconds), rather than conventional slow heating to moderate temperatures (650°C). This parameter change allows achieving anatase phase conversion while minimizing tensile stress and crack formation.
Solution Approach 2:
The patent employs pulsed or periodic heating action using flash lamps or laser pulses, applying thermal energy in repeated short bursts. This periodic thermal action enables cumulative phase transformation while allowing stress relaxation between pulses, preventing crack formation.
2Reliability
If thick TiOx layers are formed, then self-cleaning capability is improved, but tensile stress and crack formation increase
Solution Approach 1:
The patent applies rapid thermal processing parameters to thick TiOx layers, heating them to 2000-4000°C for microseconds to seconds. This parameter change enables phase conversion in thick layers without generating excessive tensile stress that would cause cracking.
Solution Approach 2:
The patent rushes through the phase transformation process by applying extreme temperatures for very short durations, skipping the prolonged intermediate states that would allow stress accumulation and crack formation in thick layers.
3Reliability
If conventional heating is used for TiOx activation, then anatase phase is achieved, but substrate overheating occurs
Solution Approach 1:
The patent applies heating locally to only the TiOx coating layer using flash lamps or laser beams that selectively heat the coating while leaving the substrate relatively cool. This local quality approach achieves phase conversion without substrate overheating.
Solution Approach 2:
The patent uses pulsed heating action with flash lamps or lasers, applying thermal energy in short bursts that heat the coating rapidly before heat can conduct to the substrate, preventing substrate overheating while achieving phase conversion.
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 achieves TiOx layers with reduced stress and increased thickness, maintaining photocatalytic properties and optical transparency, enhancing the durability and self-cleaning capabilities of low-maintenance glass coatings.
Implementation Method 1
the sputter-deposited intermediate layer is exposed to radiation to convert the intermediate layer into a layer comprising TiOx
Implementation Method 2
the conversion may remove nitrogen from, and introduce oxygen into, the intermediate layer, so as to cause the layer comprising or consisting essentially of TiOx to have a second thickness that is at least a 70% expansion beyond the first thickness
Implementation Method 3
An intermediate layer comprising Ti and N is sputter-deposited, directly or indirectly, on a first major surface the substrate
Data Source
AI summary
Certain example embodiments of this invention relate to techniques for converting sputter-deposited TiNx or TiOxNy layers into TiOx layers via activation with electromagnetic radiation. An intermediate layer including TiOxNy, 0<y≤1 is formed on a substrate. The intermediate layer is exposed to the radiation, which is preferentially absorbed by the intermediate layer in an amount sufficient to heat the intermediate layer to a temperature of 500-650 degrees C. while keeping the substrate at a significantly lower temperature. A flash light operated with a series of millisecond or sub-millisecond length pulses may be used in this regard. The converting removes nitrogen from, and introduces oxygen into, the intermediate layer, causing the layer to expand beyond its initial thickness. At least some of the final layer may have an anatase phase, and it may be photocatalytic. These layers may be used in low-maintenance glass, antireflective, and/or other applications.