Ceramic Coloring via Atmosphere Powder Sintering
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Solution Overview
Problem
Ceramic materials, such as zirconia used in dental prostheses, often have an unacceptable white color that requires additional processing steps for coloring, which can compromise mechanical properties and lead to color instability and discoloration due to environmental conditions during sintering.
Innovation Solution
A method of coloring ceramic materials in-situ during the sintering process using a ceramic-based atmosphere powder containing coloring agents, which stabilizes the color and enhances hydrolytic stability, while preventing discoloration from impurities in the furnace chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional coloring methods (stain/liner or coloring solutions) are used, then the ceramic can be colored, but additional processing steps are required and mechanical properties are compromised
Solution Approach 1:
The patent combines the coloring process with the sintering process by introducing coloring agents through atmosphere powder during sintering. This merging of operations eliminates separate coloring steps while achieving the desired color, directly resolving the contradiction between color stability and processing complexity
Solution Approach 2:
The atmosphere powder is prepared in advance with specific coloring agents and ceramic materials. During sintering, this pre-prepared powder is introduced to provide both the coloring agents and a controlled atmosphere, performing multiple functions in advance to simplify the overall process
2Stability of the object's composition
If traditional coloring methods are used, then the ceramic can be colored, but color instability and discoloration occur due to environmental conditions during sintering
Solution Approach 1:
The atmosphere powder creates a controlled chemical environment during sintering that protects the coloring agents from adverse reactions. The powder acts as a buffer, maintaining stable partial pressures of coloring agent vapors and preventing discoloration from furnace chamber impurities, thus ensuring color consistency
Solution Approach 2:
The atmosphere powder serves as an intermediary medium between the coloring agents and the ceramic material. It controls the release and distribution of coloring agents, ensuring uniform coloration while protecting against environmental contamination that would cause discoloration
3Stability of the object's composition
If coloring agents are introduced during sintering, then color is achieved, but mechanical properties may be compromised
Solution Approach 1:
The atmosphere powder is formulated as a composite material containing both coloring agents and inert ceramic materials (such as zirconia, alumina, or silica). The ceramic carrier provides structural support and protects the coloring agents, while the coloring agents are released in controlled amounts during sintering, ensuring both coloration and mechanical strength
4Stability of the object's composition
If extra processing steps are added for coloring, then color can be achieved, but production time and complexity increase
Solution Approach 1:
The coloring operation is merged with the sintering operation, which is already a necessary step in ceramic fabrication. By introducing coloring agents during sintering through atmosphere powder, the process achieves both densification and coloration in one step, eliminating separate coloring operations and improving productivity
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 eliminates extra processing steps, maintains the mechanical properties of the ceramic, ensures color stability under various conditions, and prevents unintended discoloration, resulting in high-strength, tooth-colored dental ceramic frameworks.
Implementation Method 1
The atmosphere powder can be formulated to release coloring agents at specific temperatures during the sintering process
Implementation Method 2
The coloring agents are released from the atmosphere powder and diffuse into the ceramic material during sintering
Implementation Method 3
The atmosphere powder acts as a barrier against oxidation and discoloration during the sintering process
Data Source
AI summary
Methods of forming a colored ceramic body or dental article are described that include: (a) forming a body from a ceramic-containing powder; (b) shaping the body into a desired shape; and (c) firing the shaped body in an atmosphere comprising at least one coloring agent. Methods of forming a fully dense ceramic body that lacks discoloration, are also described which include: (a) forming a body from a ceramic-containing powder; (b) shaping the body into a desired shape; (c) placing the shaped body in a firing atmosphere containing at least one impurity that promote discoloration of the ceramic body; (d) placing the ceramic body in proximity to an atmosphere powder; and (e) firing the shaped body in proximity to an atmosphere powder; wherein the atmosphere powder acts as at least one of a barrier and a getter for the at least one impurity.