DLC Coating Thermal Stability via Zinc Oxide Release Layer
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Solution Overview
Problem
Diamond-like carbon (DLC) coatings used in glass articles for scratch resistance tend to oxidize and burn off at high temperatures during heat treatment processes, such as thermal tempering, due to their susceptibility in oxygen-rich environments, leading to burn marks and reduced thermal stability.
Innovation Solution
A method involving ion beam treatment of the zinc oxide release layer with oxygen plasma before depositing an oxygen barrier layer improves thermal stability and prevents burn-off, allowing the DLC layer to withstand high temperatures without significant oxidation, and the protective film can be easily removed post-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If DLC coating is applied to provide scratch resistance, then scratch resistance is improved, but thermal stability deteriorates due to oxidation and burn-off at high temperatures
Solution Approach 1:
A multi-layer protective film system is introduced as an intermediary between the DLC coating and the high-temperature environment. The protective film includes a first layer (e.g., silicon oxide or silicon nitride) that provides oxygen barrier protection, and a second layer (e.g., zinc oxide) that serves as a release layer. This intermediary structure prevents direct contact between oxygen and the DLC coating during heat treatment, thereby preventing oxidation while allowing the DLC to maintain its scratch resistance properties.
Solution Approach 2:
The protective film is constructed as a composite material system combining different materials with complementary properties. The first layer uses materials like silicon oxide or silicon nitride for oxygen barrier properties, while the second layer uses zinc oxide for easy removal after heat treatment. This composite structure addresses both the thermal stability requirement and the subsequent ease of processing requirements.
2Stability of the object's composition
If protective film is applied to prevent DLC oxidation during heat treatment, then thermal stability is improved, but device complexity increases due to additional layers
Solution Approach 1:
The protective film is segmented into two distinct functional layers: a first layer (silicon oxide or silicon nitride) for oxygen barrier protection and a second layer (zinc oxide) for release and easy removal. This segmentation allows each layer to be optimized for its specific function, with the first layer providing thermal protection and the second layer enabling post-treatment processing without requiring complex single-layer materials.
Solution Approach 2:
The invention changes the chemical and physical parameters of the protective film layers to achieve different functions. The first layer is selected for its low oxygen permeability and high thermal stability, while the second layer is selected for its reactivity with removal solutions. By controlling deposition parameters and material composition, the system achieves both protection and ease of removal without excessive complexity.
3Ease of manufacture
If conventional protective film is used without ion beam treatment, then manufacturing process is simpler, but thermal stability deteriorates due to burn marks and incomplete protection
Solution Approach 1:
Ion beam treatment is applied as a preliminary action to the protective film before heat treatment. This treatment modifies the surface properties of the protective film layers, enhancing their protective capabilities. The ion beam treatment creates a more dense and chemically stable surface structure that better resists oxygen penetration and thermal degradation, preventing burn marks on the DLC coating during subsequent heat treatment.
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 reduces burn marks, enhances thermal and humidity stability, and facilitates easy removal of the protective film, ensuring the DLC layer remains intact and functional after heat treatment, providing improved scratch resistance and durability.
Implementation Method 1
ion beam treatment of the zinc oxide release layer with oxygen plasma before depositing an oxygen barrier layer improves thermal stability and prevents burn-off
Implementation Method 2
ion beam treatment of the zinc oxide release layer with oxygen plasma
Implementation Method 3
DLC tends to oxidize and burn off at temperatures of from approximately 380 to 400 degrees C., as the heat treatment is typically conducted in an atmosphere including oxygen
Implementation Method 4
heat treating a glass substrate coated with at least layer of or including carbon (e.g., diamond-like carbon (DLC)) and an overlying protective film thereon
Data Source
AI summary
A coated article includes a glass substrate supporting a coating. The coating may include, moving away from the glass substrate, a layer comprising diamond-like carbon (DLC); a layer comprising zinc oxide, wherein a concentration of OH-groups at a surface of the layer comprising zinc oxide farthest from the glass substrate is no greater than about 40%; and a layer comprising aluminum nitride on the glass substrate over and directly contacting the layer comprising zinc oxide. The DLC layer may be temporary, and designed to be burned off during heat treatment.