CN1040932A - Ultrasonic atomizing preparation of superfine powder - Google Patents

Abstract

The invention belongs to the fine ceramics preparing raw material, feature is to adopt the ultrasonic spray pyrolysis legal system to be equipped with oxide ceramics ultrafine powder such as zirconium white, aluminum oxide, present device is simple, easy to operate, be easy to promote, it is good to make the product powder property, and particle is spherical in shape, be difficult for reuniting granularity and distributed components.

Description

Ultrasonic atomizing preparation of superfine powder

The invention belongs to the fine ceramics preparing raw material, relate in particular to the ultrasonic spray pyrolysis legal system and be equipped with zirconium white, the technology and the device of oxide ceramics ultrafine powder such as aluminum oxide.

Oxide ceramic powder, especially Zirconium oxide powder is important fine ceramics starting material, be subjected to the increasingly extensive attention of people, at present, generally all adopt coprecipitation method both at home and abroad, with certain zirconates with need certain salt (as doped aluminium time can use aluminum chloride) of doped element to be made into the aqueous solution together, add the ammonium hydroxide hydrogen peroxide and form precipitation, oven dry, get final product to such an extent that be mixed with the Zirconium oxide powder of aluminum oxide after fusing, this method does not need specific installation, is easy to left-hand seat, also be easy to the amplification scale, but this technology there is significant disadvantages:

1. the gained powder is easy to reunite, though its primary particle can be carefully to 0.01～0.03 μ, they always are agglomerated into several μ even bigger particle, therefore, must could use behind the ball milling.

2. the powder particle shape is bad, and corner angle are clearly demarcated.

3. composition profiles is even inadequately, and segregation phenomena is arranged.

2nd, 3 obviously is to cause owing to liquid phase reaction and crystallisation process, in order to seek better preparation technology, there is exploration to prepare ultrafine zirconia powder abroad with spray pyrolysis, be about to the solution that coprecipitation method is joined, hydro-oxidation ammonium etc. does not form throw out, pyrolytic reaction takes place in the high-temperature reactor and generate fines but its atomisation sent into.Up to the present, people come atomized soln with high velocity air, and for the ease of removing reasons such as big drop, adopt of reactor is arranged vertically more, this technology than coprecipitation method much easy and simple to handle, powder is difficult for reuniting and distributed components, but owing to adopt airsream atomizer, has brought the shortcoming that is difficult to avoid to it again.

1. droplet is thicker, and size is inhomogeneous, remove big drop after, nebulization efficiency is then very low, so very difficult production ultrafine powder on a large scale.

2. during with high-speed gas atomization solution, the droplet size is directly related with gas velocity, like this with regard to impossible independent regulation carrier gas flux, that is the speed of can not the independent regulation drop passing reactor, the thin spherical shell that the result can only obtain differing in size.

In order to solve these problems in the existing spray pyrolysis process, improve the distribution of sizes of droplet, make the speed-controllable system of droplet through reactor, improve powder size, pattern and hollow degree, the present invention proposes the apparatus and method that a kind of follow-on spray pyrolysis prepares the oxide ceramics ultrafine powder, this method not only equipment is simple, and is easy and simple to handle, and powder is not reunited, shapeliness and composition profiles are even especially, and the corrosive liquid that can atomize.

Main contents of the present invention are as follows:

1. replace the general airsream atomizer feed liquid that atomizes with the ultrasonic atomizatio method.

2. adopt a kind of sound passing membrane that feed liquid and sound bearing medium are isolated, the atomisation unit that has one or more ultrasonic transducer dot matrixs to arrange under the film is realized ultrasonic atomizatio.

3. reactor is taked horizontally disposed

4. collect powder and handle tail gas with multistage bubbling water absorption method.

This spray pyrolysis unit is divided into three major portions, the one, atomisation unit, the 2nd, reactor, the 3rd, powder catcher.

The function of atomisation unit is that the defeated next solution mist of feeder system is changed into drop, under the carrying secretly of carrier gas, it is sent into reactor again.

The ultimate principle of ultrasonic atomizatio is the piezoelectric activity by means of piezoquartz, the high-frequency electromagnetic vibration is converted into the mechanical vibration of liquid, again because cavatition is broken up and mist formation the wave head of solution, now general ultrasonic atomizer all is used for atomized water, transverter all directly places water, because the atomization quantity that needs is little, so a transverter gets final product, in order to allow its mordant feed liquid that atomizes, adopt film to separate with the feed liquid that needs atomizing as transaudient water with heat-eliminating medium, for increasing atomization quantity, the transverter and the linked method that have also adopted a plurality of one-tenth dot matrixs to distribute, what, then decide on required atomization quantity as for use a transverter actually.

Reactor mainly is made up of a silica tube that is inserted in the tube type resistance furnace, silica tube one end links to each other it by a securing gear with the spraying gun outlet, for avoiding leaking, securing gear should add sealing-ring, joins a watercooling jacket again to guarantee that sealing-ring can works better.

The ultimate principle of powder collection is that the gas-powder mixture that will export directly feeds bubbling in the water, thereby reaches the dual purpose of collecting powder and vent gas treatment.

During the preparation powder, raw material (adding the salt that needs hotchpotch as zirconates or zirconates) is made into the aqueous solution of 0.5～2.5M, be contained in the loader, be injected in the atomization tank with infusion pump, under the ultrasonic wave effect of about 2MHz, be atomized into mist, carry secretly down at the pressurized air (also available bottle oxugen) that air compressor machine produced again, inflow is heated in 500～1300 ℃ of reactors by tube type resistance furnace, the very fast evaporation of solution droplet, and the generation pyrolytic reaction, be generated as the oxide ceramics ultrafine powder and in collector, be collected, dry through diafiltration again.

Description of drawings: Fig. 1 is a ultrasonic atomizatio ultrafine powder device block diagram

Fig. 2 is atomizer structure figure

[1] air compressor machine, [2] ultrasonic atomizer, [3] loader

[4] resistance furnace, [5] reactor, [6] powder catcher

[7] carrier gas inlet, [8] ultrasonic vibrator, [9] atomization tank

[10] material liquid entrance, [11] transaudient with heat-eliminating medium,

[12] atomization gas outlet

Compared with prior art, the present invention has following advantages:

1. equipment is simple, is easy to promote.

2. easy and simple to handle, stable, because of manual operations seldom, so an operator can operate multiple devices simultaneously.

3. can produce continuously

4. the product powder property is good

A. particle is spherical in shape

B. fineness ratio is more even

C. be difficult for reuniting

D. component distributing is very even

So, not only can reduce sintering temperature with this powder product, and can improve the intensity of ceramic member.

Embodiment 1

Weighing 100g ZrOCl ₂8H ₂O and 7.35g Y(NO ₃) ₃6H ₂O places a beaker altogether, the deionized water that adds 300ml, stir and suitably heating, it is dissolved fully, with infusion pump it is progressively injected atomization tank, start pressurized air that ultrasonic atomizer power supply usefulness～15l/ divides and feed liquid fog is written into by resistance furnace gives in the quartz reactor that is heated to 800 ℃ earlier, the feed liquid droplet evaporate in reactor, the formation powder particle is collected the device collection after the pyrolysis.Diafiltration after taking out, oven dry promptly get and contain 3Mol% Y ₂O ₃Zirconium oxide micro powder, with scanning electron microscope observation its pattern, particle is garden sphere very, through the analysis of X-ray diffractometer, its microtexture is a cube type, recording its specific surface with low-temperature nitrogen adsorption method is 24m ²/ g.

Embodiment 2

The ZrOCl of preparation 1M ₂.8H ₂The aqueous solution of O, with infusion pump it is progressively injected atomization tank, behind ultrasonic atomizatio, go into by electric furnace to give in the quartz reactor that is heated to 900 ℃ earlier with the pressurized air carrier band that 10～15l/ divides, after evaporation in reactor, the pyrolytic reaction, the powder particle that generates is collected in the collector, takes out the diafiltration oven dry and promptly gets pure ZrO ₂Ultrafine powder is the garden sphere with its pattern of scanning electron microscopic observation, uniform particles, and recording its specific surface is 4.19m ²/ g, its microtexture is an oblique crystal.

Embodiment 3:

Weighing 100g zirconium chloride and 12.5g Yttrium trinitrate (YCNO ₃) ₃.6H ₂O adds the 300ml deionized water, stirs and suitably heating, and it is dissolved fully, is injected into spraying gun with infusion pump equally, and the bottle oxugen carrier band with 8l/min behind ultrasonic atomizatio is gone into reactor, and all the other conditions and operation are the same, and the result gets ZrO ₂+ 5mol% Y ₂O ₃Ultrafine powder, the scanning electron microscopic observation particle is the garden sphere, recording its specific surface area is 18m ²/ g, crystalline phase is based on cube mutually.

Claims (3)

1, spray pyrolysis prepares ultrafine powder, it is characterized in that said spray pyrolysis adopts the ultrasonic atomizatio method, preparation of raw material is become the aqueous solution of 0.1～2.5M, be contained in the loader [3], be injected in the atomization tank [9] with infusion pump, under the effect of ultrasonic vibrator [8], be atomized into mist, carry secretly at the pressurized air (available bottle oxugen) that air compressor machine [1] is produced and to flow into down in the reactor [5] that is heated to 500～1300 ℃ by resistance furnace [4], the very fast evaporation of solution droplet, pyrolytic reaction taking place simultaneously, generate the ceramic ultrafine powder end, is collected at powder catcher [6].

2, method according to claim 1, it is characterized in that preparing zirconium oxide micro powder reactor and temperature is 600～1000 ℃.

3, spray pyrolysis prepares the device of ultrafine powder, comprise air compressor machine [1], spraying plant, resistance furnace, reactor, collector, it is characterized in that said atomisation unit, for a kind of sound passing membrane feed liquid and sound bearing medium are isolated, 1 above ultrasonic transducer dot matrix is arranged behind the film.