CN101508578A

CN101508578A - Heterogeneous nucleation preparation method for LaPO4 coated Al2O3, ZrO2 composite powder body

Info

Publication number: CN101508578A
Application number: CNA2009100199654A
Authority: CN
Inventors: 王昕�; 郑秋菊; 宫承鹏; 尹衍升
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2009-03-21
Filing date: 2009-03-21
Publication date: 2009-08-19

Abstract

The invention relates to a method for preparing composite powder of Al2O3 and ZrO2 coated by LaPO4 by means of nonuniform nucleation. The method is characterized in that the composite powder of Al2O3 and ZrO2 with a certain proportion is placed in deionized water first; a dispersing agent is added to the deionized water for carrying out ultrasonic dispersion to produce suspending liquid; 50-200ml of La(NO3)3 aqueous solution is added to the suspending liquid and magnetic force stirring is carried out for 30-100min; then under the magnetic force stirring, Na3PO4 aqueous solution with the same volume and concentration as the La(NO3)3 aqueous solution is dropped to the suspending liquid, with the speed of 5-15 drops/min; in the processing of dropping, the pH value of the suspending liquid is kept invariable; after the dropping is finished, the suspending liquid is stirred for another 1-3 hours, then impurity ions in the suspending liquid are washed by the deionized water, the suspending liquid is placed in a drying cabinet and dried, and finally the obtained powder is calcined. The method of the invention has simple steps and easy controllability; in addition, with the method adopted, not only can a weak interface between LaPO4 and Al2O3 and ZrO2 be obtained, but also the content of soft phase LaPO4 can be reduced; as a result, better processability can be obtained at the cost of losing lesser mechanical property.

Description

LaPO 4Coat Al 2O 3, ZrO 2The heterogeneous nucleation preparation method of composite granule

Technical field

The present invention relates to a kind of preparation method of inorganic compounding powder, particularly relate to a kind of LaPO ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule.

Background technology

ZTA (ZrO ₂Toughness reinforcing Al ₂O ₃) composite ceramics possesses good corrosion resistance, thermal shock resistance, higher intensity and toughness, might solve reliability and endurance issues that the restriction ceramic material is used, have broad application prospects.But the workability of ZTA composite ceramics is still being limited to it to a great extent in many-sided popularization.In order to improve the machinability of ZTA ceramic material, people are LaPO ₄Join Al ₂O ₃, ZrO ₂In the matrix, broken through the restriction of pottery on processing characteristics, made ceramic material have more wide application prospect.This composite ceramics has good chemical compatibility, and its fusing point height has excellent stability under oxidizing atmosphere.But with LaPO ₄And Al ₂O ₃, ZrO ₂Directly mix, need LaPO ₄Amount more, and LaPO ₄Be again weak phase, add the mechanical properties decrease that can make too much material.

Heterogeneous nucleation process is a kind of method commonly used during powder coats, it is being the nucleation matrix by coatedparticles, concentration by coating layer material in the control solution is no more than limit crystallization concentration, promptly is controlled between the required threshold value of required threshold value of heterogeneous nucleation and homogeneous nucleation.Can satisfy with this understanding the condition of heterogeneous nucleation, growth, thereby realize the coating process of particle.Although the requirement to synthetic environment is very unique, it can accurately control the thickness of coating particles and its chemical composition.At present, prepare LaPO with heterogeneous nucleation process ₄Coat Al ₂O ₃, ZrO ₂Composite granule does not also have relevant report both at home and abroad.

Summary of the invention

The object of the present invention is to provide a kind of LaPO ₄Coat Al ₂O ₃, ZrO ₂The preparation method of the heterogeneous nucleation of composite granule is to overcome above shortcomings in the prior art.

A kind of LaPO ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that at first with a certain proportion of Al ₂O ₃, ZrO ₂Composite granule is put into deionized water, adds dispersant and carries out ultrasonic dispersion, makes suspension, again with 50～200ml La (NO ₃) ₃The aqueous solution joins in this suspension, and magnetic agitation 30～100min drips and La (NO in this suspension under magnetic agitation then ₃) ₃The isocyatic Na of aqueous solution equal-volume ₃PO ₄The aqueous solution, rate of addition are 5～15/min, in the dropping process, make the pH value of suspension keep constant, after dropping finishes, continue again to stir 1～3h, with deionized water the foreign ion in the suspension is cleaned then, it is dry to put into drying box, at last with powder calcination.

The present invention takes the lead in heterogeneous nucleation process is introduced into LaPO ₄In/ZTA the composite manufacture, step is simple, easy to control, both can obtain LaPO ₄And Al ₂O ₃, ZrO ₂Between weak interface, can reduce soft phase LaPO again ₄Content, by such design, can sacrifice littler mechanical property and obtain preferably processing characteristics, overcome LaPO ₄The difficult problem of/ZTA pottery aspect processing makes it obtain further promotion and application.

Description of drawings

Fig. 1 is LaPO ₄Coat Al ₂O ₃, ZrO ₂Composite granule and X-ray diffraction comparison diagram (a) coated powder (b) that do not coat composite granule be coated powder not.

Fig. 2 is LaPO ₄Coat Al ₂O ₃, ZrO ₂The transmission electron microscope picture of composite granule.

Embodiment

The present invention selects La (NO ₃) ₃6H ₂O, NaPO ₄12H ₂O and Al ₂O ₃, ZrO ₂As raw material, Al in the composite granule ₂O ₃With ZrO ₂Mass ratio be 4:1, volume ratio is 6.26:1.With La (NO ₃) ₃6H ₂O and Na ₃PO ₄12H ₂O is made into respectively the aqueous solution that concentration is 0.01mol/L.Before the coating process is carried out, in order to reduce particle agglomeration, obtain disperseing preferably Al ₂O ₃With ZrO ₂Composite granule suspension takes by weighing Al in proportion ₂O ₃With ZrO ₂Powder 1.5g puts into the 200ml deionized water, and making the pH of suspension value with the setting of NaOH solution is 10, adds 0.5wt% dispersant ammonium polymethacrylate (PMAA), ultrasonic dispersion 120min.Then with the La (NO of 150ml ₃) ₃The aqueous solution joins in this suspension, with agitator magnetic agitation 60min.Then with the isocyatic above-mentioned Na of equal-volume ₃PO ₄The aqueous solution splashes into this suspension, and it is slower that rate of addition must be controlled, because rate of addition is too fast, makes LaPO easily ₄Produce homogeneous nucleation, influence covered effect, therefore control rate of addition at 15/min.Whole dropping process all will be carried out under magnetic agitation, to keep Al ₂O ₃With ZrO ₂The suspension of particle.After dropping finishes, suspension is continued to stir 2h again, then with deionized water that foreign ion wherein is clean, put into 60 ℃ of lower dry 12h of drying box.At last powder is calcined 2h at 1000 ℃, just obtain LaPO ₄Coat Al ₂O ₃, ZrO ₂Composite granule.

Among the present invention to LaPO ₄Coat Al ₂O ₃, ZrO ₂The test of composite granule has X-ray diffraction (XRD), transmission electron microscope (TEM).B is the Al before coating among Fig. 1 ₂O ₃And ZrO ₂The XRD of composite granule figure, a are the XRD figure of the coated powder that makes, can see Al from this figure ₂O ₃And ZrO ₂Composite granule is after being wrapped by one deck LaPO4, and the intensity of its diffraction maximum obviously descends, and LaPO ₄Diffraction maximum then more obvious.The variation explanation α-Al of this diffraction peak intensity ₂O ₃Particle surface has coated one deck LaPO ₄Can see LaPO by Fig. 2 transmission electron microscope photo ₄Not to be coated on Al with membranaceous form ₂O ₃With ZrO ₂The surface of composite granule, but formed nano level fine particle and be adsorbed on the surface of composite granule, but still belonging to the nucleocapsid clad structure, nuclear is by a plurality of Al ₂O ₃With ZrO ₂Particle aggregation forms, and shell is by one deck nanoscale LaPO ₄Particle forms, and thickness changes between 10～30nm.

Al described in the present invention ₂O ₃, ZrO ₂The average grain diameter of particle is 50～300nm; Described La (NO ₃) ₃6H ₂O and NaPO ₄12H ₂The concentration of the O aqueous solution is 0.001～0.1mol/L; Al in the described composite granule ₂O ₃With ZrO ₂Mass ratio be 2～6:1, Al ₂O ₃, ZrO ₂The weight ratio scope of composite granule and deionized water is 1:50～300, and the concentration of dispersant ammonium polymethacrylate in suspension of adding is 0.1～1wt%; The pH value scope of suspension is 1～12 in the described dropping process; Described baking temperature is 40～100 ℃, and be 8～16h drying time; Described calcining heat is 800～1200 ℃, and calcination time is 1～3h; Described dispersant is ammonium polymethacrylate, polyethylene glycol or citric acid.

Claims

1, a kind of LaPO ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that at first with a certain proportion of Al ₂O ₃, ZrO ₂Composite granule is put into deionized water, adds dispersant and carries out ultrasonic dispersion, makes suspension, again with 50～200ml La (NO ₃) ₃The aqueous solution joins in this suspension, and magnetic agitation 30～100min drips and La (NO in this suspension under magnetic agitation then ₃) ₃The isocyatic Na of aqueous solution equal-volume ₃PO ₄The aqueous solution, rate of addition are 5～15/min, in the dropping process, make the pH value of suspension keep constant, after dropping finishes, continue again to stir 1～3h, with deionized water the foreign ion in the suspension is cleaned then, it is dry to put into drying box, at last with powder calcination.

2, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described Al ₂O ₃, ZrO ₂The average grain diameter of composite granule is about 50～300nm.

3, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described La (NO ₃) ₃6H ₂O and NaPO ₄12H ₂The concentration of the O aqueous solution is 0.001～0.1mol/L.

4, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described Al ₂O ₃, ZrO ₂Al in the composite granule ₂O ₃With ZrO ₂Mass ratio be 2～6:1, Al ₂O ₃, ZrO ₂The weight ratio scope of composite granule and deionized water is 1:50～300, and the concentration of dispersant ammonium polymethacrylate in suspension of adding is 0.1～1wt%.

5, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that the pH value scope of suspension in the described dropping process is 1～12.

6, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described baking temperature is 40～100 ℃, and be 8～16h drying time.

7, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described calcining heat is 800～1200 ℃, and calcination time is 1～3h.

8, LaPO as claimed in claim 1 ₄Coat Al ₂O ₃, ZrO ₂The heterogeneous nucleation preparation method of composite granule is characterized in that described dispersant is ammonium polymethacrylate, polyethylene glycol or citric acid.