Colloidal Coloring of Zirconia Ceramic Slurry

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Solution Overview

Problem

Current methods for coloring ceramics result in inhomogeneous surface and internal coloration due to reliance on post-fabrication dipping processes, which are influenced by the properties of the coloring solution, leading to inconsistent results and lack of innate coloration.

Innovation Solution

Introducing a coloring solution comprising metallic salts, an organic solvent, and an acid into the ceramic slurry during the slip casting process, ensuring homogeneous mixing and subsequent sintering to achieve a uniformly colored ceramic body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a pre-sintered ceramic body is dipped into a coloring solution, then the ceramic can be colored, but the coloring is inhomogeneous on the surface and poor penetration occurs

Engineering Contradiction:
Improvecoloring processVSAvoidcolor uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The coloring solution is mixed with the ceramic slurry before casting, so the colorants are incorporated into the slip matrix in advance. This preliminary mixing ensures uniform distribution of colorants throughout the ceramic body before shaping and sintering, eliminating the need for post-sintering dipping operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The coloring solution is merged with the ceramic slurry to form a homogeneous mixture. By combining the colorant-containing liquid with the slip material before casting, the invention creates a unified composition where colorants are distributed throughout the entire ceramic body, resulting in uniform internal and surface coloration.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If the coloring solution properties are optimized for penetration, then color penetration improves, but the process complexity increases

Engineering Contradiction:
Improvecolor penetrationVSAvoidcoloring solution composition
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention modifies the physical and chemical parameters of the coloring solution to match the properties of the ceramic slurry. By adjusting viscosity, pH, and other parameters to be comparable to the slip, the coloring solution achieves natural integration without requiring complex optimization of individual solution properties.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If coloring is performed after ceramic fabrication, then the ceramic structure is maintained, but the color is not innate to the ceramic

Engineering Contradiction:
Improveceramic structureVSAvoidcolor integration
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

Colorants are added to the slurry before casting, allowing the color to be incorporated into the ceramic structure during the forming process itself. This preliminary addition of colorants ensures the color becomes an integral part of the ceramic matrix, creating an innate color that is uniform throughout the body.

Inventive Principle:
Principle #10Preliminary action

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 process ensures complete and homogeneous color penetration throughout the ceramic, eliminating the need for additional coloring steps and maintaining mechanical and optical properties, with the ability to produce ceramics matching specific dental shade standards like VITA Classic.

Implementation Method 1

The primary property of the metallic salt is such that is soluble in the solvent

Methodology Applied
Scientific EffectSolubility: Solvation

Implementation Method 2

The solution is thoroughly mixed with the ceramic slurry

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 3

The solution is thoroughly mixed with the ceramic slurry, after which the ceramic body is cast

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

the ceramic body is cast, dried and finally subjected to a sintering process

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentUS10202306B2Method for coloring ceramics via colloidal dispersion
Publication Date: 2019.02.12 JAMES R GLIDEWELL DENTAL CERAMICS

AI summary

In a method of coloring a ceramic material, a coloring solution consisting of metallic salts is introduced to a ceramic slurry. In a slip casting process, a coloring solution consisting of metallic salts is introduced to a ceramic slurry which is cast into green state bodies. A coloring solution that may comprise for example a metallic salt, a solvent, an organic solvent such as derivatives of propylene oxides, and an acid can be introduced to the slip casting process. Such a coloring solution can be added to the slip casting process. In a method, the coloring solution is thoroughly mixed with the ceramic slurry, after which a ceramic body is cast, dried and finally subjected to a sintering process. After final sinter, the resulting ceramic body possesses an innate color that is homogenous throughout its composition. The method is especially useful for coloring zirconia ceramic material used for making dental restorations.