Rubidium Oxide Lithium Silicate Glass Ceramic Thermal Expansion
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Solution Overview
Problem
Existing lithium silicate glass ceramics lack the ability to adjust their linear thermal expansion coefficient within a wide range, particularly from 9.0 to 14.0 × 10^-6 K^-1, and often require alkaline earth metal oxides and alkali metal oxides for production, which limits their suitability for veneering dental restorations with varying materials.
Innovation Solution
A lithium silicate glass ceramic composition containing SiO2, Li2O, Rb2O, Al2O3, P2O5, and ZrO2, without K2O, Na2O, or BaO, allowing for a wide range of thermal expansion coefficients and excellent optical and mechanical properties, suitable for veneering oxide ceramics and metal restorations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional lithium silicate glass ceramics containing BaO, K2O, and/or Na2O are used, then the glass ceramics can be produced with standard formulations, but the linear thermal expansion coefficient cannot be adjusted within a wide range (9.0 to 14.0 × 10^-6 K^-1)
Solution Approach 1:
The patent applies parameter changes by systematically varying the content of Rb2O (3.0-9.0 wt%) and Al2O3 (2.0-5.0 wt%) to achieve different linear thermal expansion coefficients within the range of 9.0 to 14.0 × 10^-6 K^-1. This allows precise adjustment of the thermal expansion property while maintaining a consistent base composition of SiO2 (56.0-72.0 wt%), Li2O (13.0-18.0 wt%), and P2O5 (2.0-6.0 wt%), thereby resolving the contradiction between adaptability and composition complexity.
2Adaptability or versatility
If glass ceramics are designed for wide thermal expansion adjustment, then they can match various restorative materials, but the strength and mechanical properties deteriorate
Solution Approach 1:
The patent employs composite materials by combining specific oxide components in defined proportions: SiO2 (56.0-72.0 wt%) as the glass matrix, Li2O (13.0-18.0 wt%) for low melting point and fluidity, Rb2O (3.0-9.0 wt%) for thermal expansion control, Al2O3 (2.0-5.0 wt%) for strength enhancement, P2O5 (2.0-6.0 wt%) as nucleating agent, and optional ZrO2 (0-4.5 wt%) for toughness improvement. This composite formulation achieves both wide thermal expansion adjustability (9.0-14.0 × 10^-6 K^-1) and high flexural strength (≥350 MPa), resolving the contradiction between adaptability and strength.
3Ease of manufacture
If alkaline earth metal oxides and alkali metal oxides are used as essential components, then the glass ceramics can be produced, but the optical properties and translucency are compromised
Solution Approach 1:
The patent applies local quality by selectively optimizing the role of each oxide component: SiO2 (56.0-72.0 wt%) provides the transparent glass matrix, Li2O (13.0-18.0 wt%) ensures low melting point and good fluidity for easy manufacturing, Rb2O (3.0-9.0 wt%) controls thermal expansion, Al2O3 (2.0-5.0 wt%) enhances strength without significantly affecting translucency, and P2O5 (2.0-6.0 wt%) acts as a nucleating agent for controlled crystallization. This localized optimization of each component's function achieves both ease of manufacture and excellent optical properties with high 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 glass ceramic achieves a linear thermal expansion coefficient within 9.0 to 14.0 × 10^-6 K^-1, with high strength and fracture toughness, making it suitable for diverse dental restorations, and can be produced without conventional essential components, ensuring compatibility with various restorative materials.
Implementation Method 1
a linear coefficient of thermal expansion WAK 100-400 ° C, which is easily in a wide range of in particular 9.0 to 14.0 10 -6
Data Source
AI summary
The invention relates to the use of lithium silicate glass ceramics and glasses containing rubidium oxide for coating an oxide ceramic, a metal or an alloy.