Pre-Bent Glass Substrate for CVD Diamond Coating Stress Management
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Solution Overview
Problem
Diamond deposition on flat glass substrates often results in warping due to stress from the applied diamond or other films, which compromises the glass's flatness and durability.
Innovation Solution
A method involving pre-bending of the glass substrate to form a convex first side and a concave second side, followed by diamond coating using chemical vapor deposition (CVD) on the convex side and ion exchange modification on the substrate, which balances stresses to achieve a substantially flat diamond-coated glass structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If diamond coating is applied to flat glass substrate, then hardness and scratch resistance are improved, but warping occurs due to stress
Solution Approach 1:
The glass substrate is pre-bent before diamond coating to introduce initial stress that counteracts the stress from subsequent diamond deposition. This preliminary action ensures that when the diamond layer is applied, the combined structure returns to a flat state, eliminating warping while maintaining the hardness benefits of the diamond coating.
Solution Approach 2:
A counter-stress is intentionally introduced by bending the glass substrate in the opposite direction of the expected warping caused by diamond coating. This preliminary anti-action compensates for the stress from the diamond layer, preventing the harmful warping effect while preserving the improved hardness and scratch resistance.
2Reliability
If diamond coating is applied to increase durability, then scratch resistance is improved, but stress-induced warping compromises the structure
Solution Approach 1:
The glass substrate undergoes pre-bending to establish a stress state that will counterbalance the stress from diamond coating. This preliminary action ensures that the final coated structure maintains both the enhanced durability from the diamond layer and the required flatness for reliable operation.
Solution Approach 2:
The stress state of the glass substrate is deliberately changed by applying controlled bending forces before coating. This parameter change in the stress distribution allows the final structure to achieve both high durability from the diamond coating and maintained flatness, resolving the contradiction between reliability and shape stability.
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 effectively reduces warping while maintaining the increased hardness, scratch resistance, and unique electrical properties of diamond-coated glass, ensuring the glass substrate remains flat and durable.
Implementation Method 1
bending the substrate uses asymmetrically applied mechanical force
Implementation Method 2
bending the substrate uses thermal heating of the substrate
Implementation Method 3
A CVD diamond layer can be deposited on the convex first side of the substrate
Implementation Method 4
chemically modifying the substrate through ion exchange comprises replacement of at least some sodium ions with potassium ions
Data Source
AI summary
A method of forming a diamond coated glass structure includes providing a glass substrate having a first and a second side. The second side can be covered in whole or in part with a coating capable of reducing ion exchange. The substrate can be bent to form the first side as convex and the second side as concave. A CVD diamond layer can be deposited on the convex first side of the substrate and at least a portion of the substrate chemically modified through ion exchange. After removal of the stress, the stresses due to applied diamond layers and chemical modification through ion exchange can balance, providing a substantially flat diamond coated glass structure.