Lithium Silicate Deep Quartz Glass Ceramic Machinability
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Solution Overview
Problem
Conventional lithium disilicate glass ceramics are difficult to machine due to their high strength, leading to tool wear and requiring additional heat treatment to achieve desired mechanical properties, while also posing challenges in achieving good optical properties for aesthetic dental restorations.
Innovation Solution
The development of lithium silicate deep quartz glass ceramic with lithium silicate as the main crystal phase and deep quartz as a further crystal phase, which allows for easy machining and eliminates the need for post-processing heat treatment, while maintaining high mechanical and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional lithium disilicate glass ceramic is used to ensure high mechanical strength, then the material achieves desired strength properties, but machining becomes difficult and causes significant tool wear
Solution Approach 1:
The patent changes the chemical composition parameters of the glass ceramic by incorporating lithium silicate (40-70 wt%) combined with lithium disilicate (10-30 wt%) and quartz (10-30 wt%), along with specific oxide combinations. This parameter modification allows the material to achieve both high strength and improved machinability, resolving the contradiction between mechanical strength and ease of manufacturing.
2Ease of manufacture
If lithium metasilicate glass ceramic is used as a precursor to enable easy machining, then machining becomes significantly easier, but additional heat treatment is required to achieve desired mechanical properties
Solution Approach 1:
The patent incorporates quartz and lithium silicate phases in advance during the initial sintering process (900-1100°C), creating a microstructure that is both machineable and mechanically strong from the outset. This preliminary action eliminates the need for subsequent heat treatment steps that would otherwise be required to achieve desired mechanical properties, thus reducing processing time while maintaining ease of machining.
3Strength
If secondary crystal phases are added to lithium silicate glass ceramic to improve mechanical properties, then strength increases, but optical properties such as translucency and colorability are impaired
Solution Approach 1:
The patent creates local quality differentiation by distributing specific crystal phases (lithium disilicate and quartz) within the lithium silicate glass matrix in controlled amounts (10-30 wt% each). This localized distribution provides mechanical reinforcement in specific regions while maintaining overall translucency and colorability, as the crystal phases are dispersed rather than forming large opaque aggregates.
Solution Approach 2:
The patent creates a composite glass ceramic material combining lithium silicate (40-70 wt%), lithium disilicate (10-30 wt%), and quartz (10-30 wt%), along with specific oxide combinations. This composite structure leverages the strength-enhancing properties of the crystal phases while the dominant lithium silicate glass matrix preserves optical properties, achieving a balance between mechanical strength and translucency.
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 lithium silicate deep quartz glass ceramic achieves high strength, ease of machining, and excellent optical properties, enabling the production of dental restorations with enhanced mechanical and aesthetic qualities without requiring further heat treatment.
Implementation Method 1
The lithium silicate deep quartz glass ceramic according to the invention contains lithium silicate as the main crystal phase and deep quartz as the further crystal phase
Data Source
AI summary
Lithium silicate deep quartz glass ceramics are described, which are characterized by a combination of very good mechanical and optical properties and can therefore be used particularly as restorative material in dentistry.