Lithium Silicate Glass Ceramic Crystallization
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Solution Overview
Problem
Conventional lithium disilicate glass ceramics require high temperatures for crystallization, necessitating significant energy usage and relying on alkali metal oxides like K2O, Na2O, and La2O3 for their production, which are considered essential components.
Innovation Solution
Lithium silicate glass ceramics incorporating pentavalent metal oxides such as Nb2O5 and Ta2O5, with reduced or no alkali metal oxides, can crystallize lithium disilicate at lower temperatures (650-750°C), eliminating the need for K2O, Na2O, and La2O3, and maintaining advantageous optical and mechanical properties for dental applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional lithium disilicate glass ceramics are produced using alkali metal oxides (K2O, Na2O) and La2O3, then lithium disilicate crystal phase can be formed, but high crystallization temperatures (800-1040°C) are required resulting in high energy consumption
Solution Approach 1:
The patent changes the chemical composition parameters by replacing traditional alkali metal oxides (K2O, Na2O) and La2O3 with pentavalent metal oxides (Nb2O5, Ta2O5) in specific amounts (0.1-8.5 wt.%). This parameter change enables lithium disilicate crystallization at lower temperatures (650-750°C) while maintaining the desired crystal phase formation, thus resolving the contradiction between crystallization temperature and energy consumption
Solution Approach 2:
The patent introduces pentavalent metal oxides (Nb2O5, Ta2O5) as intermediary substances that facilitate lithium disilicate crystal formation at lower temperatures. These oxides act as mediators between the glass matrix and the desired crystal phase, enabling controlled crystallization without requiring high temperatures or traditional alkali metal oxide additives
2Ease of manufacture
If alkali metal oxides (K2O, Na2O) and La2O3 are used as essential components, then lithium disilicate glass ceramic can be produced, but the production process becomes dependent on these specific additives
Solution Approach 1:
The patent extracts and removes the dependency on alkali metal oxides (K2O, Na2O) and La2O3 from the essential components list by replacing them with pentavalent metal oxides (Nb2O5, Ta2O5). This extraction simplifies the composition requirements and eliminates the need for traditional additives that were previously considered indispensable for producing lithium disilicate glass ceramics with desired properties
3Reliability
If high crystallization temperatures (800-1040°C) are applied, then lithium disilicate crystal phase precipitates, but processing complexity and energy requirements increase
Solution Approach 1:
The patent changes the thermal processing parameters by reducing the crystallization temperature range from 800-1040°C to 650-750°C through compositional modification with pentavalent metal oxides. This parameter change simplifies the heat treatment process, reduces processing complexity, and maintains reliable lithium disilicate crystal phase formation without requiring complex high-temperature equipment or extended processing times
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 reduces energy consumption while producing glass ceramics with high fracture toughness and suitable for dental restorations, offering improved processing and optical properties without the typical essential components, allowing for efficient production and use in dental materials.
Implementation Method 1
They are prepared from corresponding nuclei-containing starting glasses which are heated to temperatures of from 850 to 870° C. for the crystallization of lithium disilicate
Data Source
AI summary
Lithium silicate glass ceramics and glasses containing specific oxides of pentavalent elements are described which crystallize at low temperatures and are suitable in particular as dental materials.