Zirconia wants to be colorful?

With many excellent properties, zirconia ceramic materials are widely used in various fields.

Since it is to be used as an ornament, the "beautiful" is the key to coating online coatingol.

We all know that zirconia ceramics itself has the advantages of high melting point and boiling point, high hardness, excellent wear resistance, skin-friendliness and so on.

But the preparation of colored zirconia is not so simple

The current preparation of colored ZrO2 essentially means that the colorant is evenly distributed in the ZrO2 matrix

Therefore, how to make the toner particles uniformly dispersed in the zirconia matrix to prepare colored zirconia ceramics with excellent mechanical properties and chromaticity, the key lies in whether the agglomeration between the powder particles can be overcome

The commonly used dispersion methods are:

①Solid phase mixing method : This method mixes and ball mills oxide particles such as colorants and mineralizers with stabilized zirconia nano-powders according to a certain chemical ratio.

②Chemical co-precipitation method: This method uses zirconium salt, stabilizer salt, and colored ion salt solution to mix, react with alkali or carbonate to form hydroxide or carbonate precipitation, and then heat to decompose.

③Liquid phase impregnation method: This method is to extract and degrease the body after injection molding to obtain a body with interconnected pore structure, and then place it in a solution containing colored phase ions for impregnation

Difficulty 2: The choice of toner

The color of the ceramic toner is mainly determined by the existence state of the colored ions, that is, the atomic or molecular structure of the toner itself.

①Ion coloring type:

The colorant is distributed in the colorant crystal in an ionic state, which is called ionic coloring.

Synthetic spinel pigment in terms of RO include MgO, ZnO, CoO, FeO, MnO , etc.
, R2O3 including Cr2O3, Fe2O3, Al2O3, Mn2O3 and so on
.
When RO and R2O3 synthesize RO·R2O3 spinel under certain conditions, the chemical stability of RO·R2O3 spinel is greatly improved compared to RO and R2O3 metal oxides
.
Since most transition metal oxides can form corresponding spinels with each other, and various spinels can be dissolved in each other to form a replacement solid solution, it provides conditions for isomorphic replacement of ions in the crystal lattice.
Therefore, a wide range of spectral colorants can be prepared
.

②Wrapped toner:

Encapsulated toner is formed by wrapping a toner that is not resistant to high temperature by a high-temperature resistant material
.
High-temperature scarlet cadmium selenium red is successfully synthesized using this method
.
There are very limited ceramic bright red agents found so far, and cadmium-selenium red can color ceramics below 800°C and present a bright red color, but when the temperature rises above 800°C, cadmium-selenium red will turn from red to black
.
In order to make cadmium-selenium red form a stable high-temperature toner at high temperatures, studies have found that cadmium-selenium red is wrapped in high-temperature-resistant zircon crystals to successfully synthesize a high-temperature-resistant bright red color
.
In addition, some studies have found that wrapping Fe2O3 in SiO2 can also prepare pure high-temperature red pigments
.
The key to preparing the wrapped colorant is not only to form high-temperature resistant crystals at high temperatures, but also to ensure that the structure of the wrapped colorant will not be damaged
.

The following are some toners that can be used in different colors:

At present, blue colorants include alum cobalt blue and cobalt blue
.
The coloring mechanism of the former is that V4+ enters the Zr-SiO4 crystal lattice to form a blue V-ZrSiO4 solid solution to make the ceramic blue or sky blue
.
Since vanadium ions of different valences have different colors, V3+ is green, V4+ is blue, and V5+ is yellow.
Therefore, to obtain high-purity vanadium zirconium blue, vanadium ions must be controlled to be tetravalent; the color element of the latter is Co, It is mainly composed of CoO or Co2O3 and Al2O3 at high temperature to synthesize cobalt aluminate (CoAlO4), which has a spinel structure
.
However, because cobalt oxide is expensive, the production cost is relatively high, except that its withstand temperature is only ~1200°C
.

Black toner is generally prepared from several transition metal oxides or metal salt solutions, such as ①Mn(NO3)2:6H2O and Al(NO3)3·9H2O; ②FeCl3, Co(NO3)26H2O, Cr(NO3)3 ·9H2O and Al(NO3)3·9H2O
.
③Co3O4, Cr2O3, TiO2 and other toner powder; ④ graphite
.

Er(NO3)3·6H2O, Fe(NO3)3·9H2O, etc.
can be used for pink and red colorants; Cr is a common green coloring element; ammonium metavanadate can be used as a blue color agent or a yellow color.
Agent (when 5-valent vanadium is dominant)
.
In addition, Azurabu has successfully synthesized golden zirconia ceramics by high-temperature plasma nitriding
.