Chemically Strengthened Glass Ceramic Amorphized Surface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chemically strengthened glass ceramics tend to have deteriorated chemical strengthening properties due to high compressive stress on the surface, leading to chipping issues after chemical strengthening treatment, as ion exchange is less likely to occur in the crystalline phase compared to the glass phase.
Innovation Solution
A method involving a heat treatment in a reducing atmosphere after crystallization to form an amorphized region on the surface of glass ceramics, enhancing ion exchange and reducing surface stress, with specific compositional and structural characteristics such as a crystallinity of 10 vol% or less at 100 nm depth and a sodium concentration difference of 10 mol% or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass ceramics are subjected to chemical strengthening treatment to obtain higher strength, then the strength is improved, but the surface compressive stress becomes too large causing end portion chipping
Solution Approach 1:
The patent applies local quality by creating an amorphized region with different properties from the crystallized region. The amorphized surface layer has lower crystallinity (10 vol% or less at 100 nm depth) compared to the interior crystallized region (20-80 vol% crystallinity), allowing the surface to have relaxed stress while the interior maintains high strength. This local differentiation resolves the contradiction between overall strength and surface chipping resistance.
2Strength
If ion exchange is performed in glass ceramics, then chemical strengthening occurs, but ion exchange is less likely to occur in the crystalline phase reducing strengthening effectiveness
Solution Approach 1:
The patent changes the crystallinity parameter locally to optimize ion exchange. By reducing crystallinity at the surface (creating amorphized region with crystallinity ≤10 vol% at 100 nm depth) while maintaining high crystallinity in the interior (20-80 vol%), the surface becomes more receptive to ion exchange. This parameter change enables effective chemical strengthening at the surface while preserving the strength benefits of crystallization in the interior.
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 results in chemically strengthened glass ceramics with improved chemical strengthening properties and relaxed surface stress, preventing chipping while maintaining excellent strength, as evidenced by enhanced ion diffusion and reduced compressive stress values.
Implementation Method 1
by performing a heat treatment in a reducing atmosphere after performing a crystallization treatment on an amorphous glass
Implementation Method 2
crystallinity in a vicinity of a main surface of the obtained glass ceramics can be reduced and an amorphized region can be formed
Implementation Method 3
ion exchange with a molten salt occurring on a glass surface during the chemical strengthening treatment becomes active
Implementation Method 4
only a compressive stress in the vicinity of the main surface, which does not affect the strength of the entire glass ceramics, is relaxed
Data Source
AI summary
The present invention relates to a chemically strengthened glass ceramic including a crystalline phase, having two main surfaces opposed to each other, and including an amorphized region in a surface layer of at least one of the main surfaces and a crystallized region inside the glass, in which the amorphized region has a crystallinity of 10 vol % or less at a depth of 100 nm from an outermost surface of the glass.