Zirconia Grey Coloration via Oxide Mixture Sintering
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Solution Overview
Problem
Existing methods for producing gray ceramic articles from zirconia result in non-uniform coloration with veining and marbling, and prevent subsequent machining due to superficial oxidation, lacking mass coloration and mechanical properties comparable to uncolored zirconia.
Innovation Solution
A process involving a mixture of zirconia powder with specific proportions of vanadium oxide, chromium oxide, silicon oxide, and stabilizers, followed by sintering in air, to achieve a uniformly colored gray ceramic article with maintained mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If zirconia is heat treated in a vacuum graphite furnace to produce gray color, then the article obtains a gray superficial oxidation, but the coloration is not uniform with veining and marbling, and the article cannot be subsequently machined
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific mixture of oxides (V2O5, Cr2O3, SiO2) in controlled proportions to the zirconia base material. This compositional modification enables uniform mass coloration during sintering while maintaining the material's machinability, resolving the contradiction between achieving uniform color and preserving subsequent processing capability
Solution Approach 2:
The patent creates a composite material system by combining zirconia with a multi-component oxide mixture (vanadium oxide, chromium oxide, and silicon oxide). This composite approach achieves uniform gray coloration throughout the mass while preserving the base zirconia's mechanical properties and machinability, eliminating the veining and marbling defects of simple heat treatment
2Illumination intensity
If pigments are added to zirconia to achieve coloration, then the article obtains desired color, but the mechanical properties are altered
Solution Approach 1:
The patent carefully controls the concentration parameters of coloring oxides, maintaining them within specific ranges (0.1-1% for V2O5, Cr2O3, and SiO2). This precise parameter control achieves sufficient mass coloration while minimizing the impact on mechanical properties, as the coloring agents remain at levels that do not significantly compromise the zirconia matrix strength
Solution Approach 2:
The patent applies the coloring oxide mixture uniformly distributed throughout the zirconia mass at low concentrations. This localized, uniform distribution ensures consistent coloration without creating weak points or significant deviations from the base material's mechanical properties, preserving strength while achieving the desired aesthetic appearance
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 produces a mass-colored, uniformly gray ceramic article with attractive aesthetic appeal and preserved mechanical properties, suitable for decorative and functional items like watch components without altering the color during machining.
Implementation Method 1
e) sintering said blank in air for at least thirty minutes at a temperature between 1250 and 1550 DEG. C.
Implementation Method 2
The process produces a mass-colored, uniformly gray ceramic article
Data Source
AI summary
The invention relates to a method for manufacturing a grey zirconia-based article characterized in that it comprises the successive steps of: a) making a first mixture comprising.- a zirconia powder forming the basic constituent, - 4 to 15% by weight of at least one stabilizer chosen from all oxides including yttrium oxide, magnesium oxide, and calcium oxide alone or in combination, - 0.1% to 1% by weight of vanadium oxide (V2O5) powder; - 0.1% to 1% by weight of chromium oxide (Cr2O3) powder; and - 0.1% to 1% by weight of silicon oxide (SiO2) powder, b) prepare a second mixture comprising said first mixture and a binder; c) prepare a granulated mixture by granulating said second mixture; d) form a blank by giving this second granulated mixture the shape of the desired article; e) sinter the said article under air for at least thirty minutes at a temperature between 1250 and 1550 DEG. C.