JPH0472768B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is based on the Showa patent application filed by the present inventor.
1957 Patent Application No. 215208 (Japanese Patent Publication No. 3-46407,
This invention is an addition to the original patent application (hereinafter referred to as the original patent application), and relates to a sol in which zirconia-based single crystal ultrafine particles containing zirconia as a basic component are dispersed, and a method for producing the same.

ZrO ₂ and Y ₂ O ₃ , CaO, MgO, CeO ₂ , etc.
Solid solutions containing one or more of oxides such as Sc, Yb, La, Nd, and Gd have various applications such as high-temperature materials, ion conductive materials, and piezoelectric materials, and ultrafine particles of these solid solutions are used as starting materials. It has already been described in detail in the original patent application that the dispersed sols are extremely useful.

However, at the time of the original patent application, ZrO ₂ −
A sol in which single-crystal ultrafine particles of a solid solution of ZrO ₂ and divalent metal ions, such as a CaO-based solid solution, are dispersed could not necessarily be obtained by the method described in the patent application. This was briefly mentioned in Example 2 of the original patent application, but as a result of subsequent research, by slightly improving the method, a similar sol with solid solution single crystal ultrafine particles dispersed could be produced for ZrO ₂ -CaO systems, etc. It has now become possible to produce this, and this is described below as an additional application.

In other words, at the time of the original patent application, Zr(OH) ₄ and 2
The defects were due to the failure to take into account the dissolution and separation of coprecipitates of valent metal hydroxides and the interfering effects of ammonium chloride. As a result of subsequent detailed research, we found that the hydroxide or co-precipitated hydroxide was washed as thoroughly as possible, and unnecessary products during precipitation, such as ammonium chloride, common salt, potassium chloride, sodium nitrate, and potassium nitrate, were washed as much as possible with water. It was found that removal is necessary for the formation of a solid solution of ZrO ₂ and divalent metal ions, and that success can only be achieved by washing with a saturated aqueous solution of the divalent metal ions in order to prevent the divalent metal ions from dissolving and disappearing at the same time. If the aging temperature is below 90°C, the production rate is too slow to be practical, and if it is above 200°C, the produced particles will become coarse and begin to aggregate and connect with each other, resulting in poor isolation, and furthermore, the elution of calcium components will increase. Finally the product is 150Å
These are ultrafine particles of about 100 mL, and they dissolve and disappear when a strong acid is added and the separation operation is performed as in the original patent application, so they are washed with dilute acetic acid, aqueous ammonia, etc., depending on the amount of solid solution such as CaO. There is a need.

In addition, after washing the zirconium hydroxide precipitate in a water-containing state with water, the inventors added an aqueous calcium hydroxide solution and heated and aged only the mixed suspension or paste to form a square shape with a low CaO content or We have newly discovered that cubic zirconia single crystal ultrafine particles are produced. This method, which is carried out without coprecipitation, is not successful with yttrium hydroxide and is suitable for relatively strong bases such as calcium hydroxide.

Although the above method is a slight improvement on the method in the original patent application, its effect is tremendous, and it makes it possible to generate a sol in which ZrO ₂ −CaO solid solution single crystal fine particles are dispersed, which has not been possible at all in the past. and other strongly basic divalent metal ions, such as
It is also applicable to Ba, Sr, etc. As a result, divalent metal hydroxides, which are cheaper than rare earth elements, can be used.
Zirconia ultrafine particles used as stabilizers or semi-stabilizers for ZrO ₂ can now be used in large quantities as raw materials for ceramics, and the fact that they are fine particles also makes them valuable as raw materials for ceramics to which divalent metal ions are added. be.

Example 1 Reagent 87 g of zirconyl chloride (ZrOCl ₂ .8H ₂ O) was dissolved in about 500 ml of water, and a sufficient amount of 1:1 aqueous ammonia was added to form a white precipitate of zirconium hydroxide. This was washed by repeated decanting with a saturated aqueous solution of calcium hydroxide. Approximately 500 ml of the mixed suspension of the zirconium hydroxide precipitate and calcium hydroxide aqueous solution obtained in this way was added.
and heated to 120℃ in a sealed Teflon container.
After holding and aging for 30 hours, a suspension with low viscosity was obtained. This was carefully washed and separated repeatedly with 1N diluted hydrochloric acid, and finally decanted twice with alcohol, and then dried at 60°C to obtain a solid mass. This solid mass is easily dispersed in water to give a sol of any concentration. According to an electron microscope, this sol is a single crystal with a shape close to a cube with a side of about 100 Å, which is almost the same as the example of the original patent (ZrO ₂ -Y ₂ O ₃ solid solution).
It was confirmed that they were ultrafine particles that were isolated and dispersed from each other.

Example 2 Reagent 87 g of zirconyl chloride (ZrOCl ₂ 8H ₂ O) was mixed with 3.4 g of calcium chloride (CaCl ₂ ) (for ZrO ₂
CaO (corresponding to about 10 mol%) was dissolved in about 500 ml of water, and this was added dropwise to a 6N caustic soda solution to obtain a co-precipitated hydroxide of zirconium and calcium. This was washed by repeated decanting with a saturated aqueous solution of calcium hydroxide. Approximately 500 ml of a mixed suspension of the coprecipitated hydroxide thus obtained and a saturated aqueous calcium hydroxide solution was prepared, and this was aged at 97°C for one week to obtain a suspension with low viscosity. This was carefully washed and separated repeatedly with 1N acetic acid, and finally decanted twice with alcohol, and then dried at 60°C to obtain a solid mass. This solid mass is easily dispersed in water to give a sol of any concentration. According to an electron microscope, it was confirmed that the single crystal had the same shape as in Example 1 except that the cube-shaped apex was rounded, and that it was ultrafine particles that were isolated and dispersed from each other.

Example 3 An equimolar mixed aqueous solution of reagents zirconyl nitrate and barium nitrate was dropped into a 3N caustic potassium aqueous solution to obtain a coprecipitate of zirconium hydroxide and barium hydroxide. A milky mixed suspension obtained by thoroughly washing this with a saturated barium hydroxide aqueous solution was aged at 97° C. for one week to obtain a suspension with low viscosity. This was carefully washed with 1N ammonia water, and then the ammonia was removed by heating. Approximately 300 Å according to an electron microscope
X-ray diffraction of the dried product showed a BaZrO ₃ crystal lattice.

Claims (1)

[Claims] 1. Has a square or cubic crystal lattice and has a crystal lattice of 200 Å.
A sol in which isolated ZrO ₂ -CaO solid solution single crystal ultrafine particles of approximately uniform particle size are dispersed. 2 Add a base to an aqueous solution of zirconium salt to form a precipitate, remove most of the soluble portion by washing with water, add an alkaline earth metal hydroxide or an aqueous solution thereof, and prepare the resulting mixed suspension or paste. 90℃～
It is characterized by heating and aging at a temperature of 200℃.
A method for producing a sol in which square or cubic ZrO ₂ single crystal ultrafine particles are dispersed. 3 Co-precipitated hydroxide of divalent metal ions such as zirconium and calcium is washed with a divalent metal hydroxide aqueous solution concentrated to the extent that the divalent metal hydroxide does not elute from the coprecipitate, resulting in coprecipitated hydroxide. zirconia-based single-crystal ultrafine particles containing divalent metal ions, characterized by heating and aging a mixed suspension or paste-like substance of a divalent metal ion and a divalent metal hydroxide saturated aqueous solution at a temperature of 90°C to 200°C. A method for producing a dispersed sol.