Zinc Oxynitride Release Layer for DLC Coating Heat Treatment
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Solution Overview
Problem
Diamond-like carbon (DLC) coatings on glass substrates used in applications like shower doors and windows are prone to oxidation and burn-off during high-temperature heat treatments due to the existing protective film's instability and susceptibility to humidity, leading to adhesion issues and corrosion.
Innovation Solution
Incorporating a zinc oxynitride release layer with a controlled nitrogen to oxygen ratio into the protective film stack, which includes an oxygen barrier layer, to create a thermally stable and electrochemically inactive interface that prevents DLC burn-off during heat treatment and facilitates easy removal post-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional protective film (zinc oxide release layer and aluminum nitride oxygen barrier layer) is used to protect DLC during heat treatment, then the DLC layer is protected from complete oxidation, but the protective film itself becomes unstable and susceptible to humidity, leading to adhesion issues and corrosion
Solution Approach 1:
The patent modifies the chemical composition parameters of the protective film by introducing zinc oxynitride (ZnOxNz) with controlled nitrogen to oxygen ratios (z/x from 0.40 to 1.2). This parameter change transforms the protective film from a two-layer structure (ZnO/AlN) to a single-layer zinc oxynitride structure, which maintains protection capability while improving stability and eliminating adhesion issues during heat treatment and storage
Solution Approach 2:
The patent creates a composite material structure within the protective film by incorporating both zinc oxide and nitrogen in specific ratios to form zinc oxynitride. This composite approach combines the protective properties of zinc oxide with the stability and adhesion benefits provided by nitrogen incorporation, resulting in a film that is both protective and stable under heat treatment conditions
2Ease of manufacture
If the protective film is designed to be easily removed after heat treatment, then post-treatment processing is simplified, but the film may not provide sufficient protection during the heat treatment process
Solution Approach 1:
The patent optimizes the nitrogen to oxygen ratio parameters in zinc oxynitride to achieve a balance between protection and removability. By controlling the z/x ratio within specific ranges (0.40 to 1.2, preferably 0.55 to 1.0), the film maintains sufficient adhesion and protection during heat treatment while remaining easily removable afterward through standard wet cleaning methods, thus resolving the contradiction between protective reliability and ease of removal
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 zinc oxynitride layer enhances the homogeneity and stability of the protective film, preventing DLC oxidation and ensuring the coating remains intact during heat treatment, while allowing for easy removal, thus maintaining the glass substrate's scratch resistance and visibility.
Implementation Method 1
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. Thus, it will be appreciated that DLC alone as a protective overcoat cannot withstand heat treatments (HT) at the extremely high temperatures described above
Implementation Method 2
Following and/or during heat treatment (e.g., thermal tempering, or the like) the protective film may be entirely or partially removed
Data Source
AI summary
A method of making a heat treated (HT) substantially transparent coated article to be used in shower door applications, window applications, tabletop applications, or any other suitable applications. For example, certain embodiments relate to a method of making a coated article including a step of 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. The protective film may be of or include both (a) an oxygen blocking or barrier layer, and (b) a release layer, with the release layer being located between at least the carbon based layer and the oxygen blocking layer. The release layer is of or includes zinc oxynitride (e.g., ZnOxNz). Following and/or during heat treatment (e.g., thermal tempering, or the like) the protective film may be entirely or partially removed. Other embodiments of this invention relate to the pre-HT coated article, or the post-HT coated article.