Zirconia Layered Body Stabilizer Gradient for Dental Prosthetics
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Solution Overview
Problem
Zirconia layered bodies with small differences in additive content often experience thermal shrinkage-related failures such as peeling or distortion during heat treatment, making it challenging to produce layered bodies with desired textures for dental prosthetics.
Innovation Solution
A layered body structure is developed with zirconia layers containing stabilizers, where the first layer has a stabilizer content of 4 mol% or higher and the second layer has a different stabilizer content, with a binding agent content difference exceeding 0.01 wt%, allowing for controlled heat treatment and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If layers with small differences in additive content are used, then the composition is easier to control, but thermal shrinkage failures such as peeling and distortion occur during heat treatment
Solution Approach 1:
The patent changes the parameter from additive content difference to stabilizer content difference. By making the stabilizer content differ by 0.5-2.0 mol% between layers while keeping additive content similar, the invention achieves both ease of manufacture and heat treatment stability. The stabilizer content gradient allows controlled thermal shrinkage behavior during sintering, preventing peeling and distortion while maintaining compositional control.
2Shape
If layers with different additive contents are used, then texture variation is achieved, but thermal shrinkage behaviors differ greatly causing peeling and distortion
Solution Approach 1:
The patent applies local quality by creating specific compositional gradients within layers. Each layer has a stabilizer content gradient (difference of 0.5-2.0 mol% across the layer thickness) that provides localized control over thermal shrinkage. This allows different regions of the layered body to shrink at controlled rates during heat treatment, achieving texture variation through stabilizer content differences while maintaining dimensional stability.
3Reliability
If special adjustment or treatment is applied to prevent failures, then heat treatment can be performed without peeling or distortion, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the stabilizer content gradient in the green body before heat treatment. By configuring the layers with appropriate stabilizer content differences (0.5-2.0 mol%) during the molding stage, the invention prepares the structure to undergo uniform thermal shrinkage during subsequent heat treatment. This eliminates the need for complex special adjustments or treatments during heat treatment, as the compositional gradient is already optimized to prevent peeling and distortion.
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 approach enables the production of layered bodies with a change in texture, particularly translucency, suitable for dental prosthetics, by controlling the stabilizer content and binding agent distribution between layers, reducing warp and deformation, and achieving densities and light transmittance similar to natural teeth.
Implementation Method 1
The raw material powder thermally shrinks and is densified through heat treatment such as sintering or calcination.
Implementation Method 2
A method for producing a sintered body by sintering a green body, and a sintered body produced by the production method
Data Source
AI summary
A layered body, which has a change in texture derived from zirconia, particularly a change in translucency and is suitable as a dental prosthetic member, a precursor thereof, or a method for producing these. The layered body has a structure in which two or more layers containing zirconia containing a stabilizer are layered, the layered body including at least: a first layer containing zirconia having a stabilizer content of higher than or equal to 4 mol %; and a second layer containing zirconia having a stabilizer content different from that of the zirconia contained in the first layer. At least a first layer and a second layer contain an element having a function of coloring zirconia and the content or the type of the element having a function of coloring zirconia in the first layer is different from the element having a function of coloring zirconia in the second layer.