Background technology
Zirconium white is because essential propertys such as its inherent chemical ingredients and crystalline structure, thereby has advantages such as chemical stability is good, heat-conduction coefficient is little, hardness is big, is a kind of important 26S Proteasome Structure and Function stupalith.Common zirconium white ℃ exists with monocline mutually at normal temperature to 1170, changes cubic phase when being heated to 1170 ℃~2370 ℃ into, becomes cube phase (2700 ℃ of left and right sides fusions) by tetragonal phase converting in the time of more than 2370 ℃.Because the high temperature phase (cube phase or cubic phase) of pure zirconia is along with the reduction of temperature can be transformed into low temperature phase (monocline phase), obtain high temperature phase zircite stable under the room temperature, some other oxide compound just need mix in zirconium white, as yttrium oxide, calcium oxide, magnesium oxide, Scium trioxide etc., form composite oxides.The mutually partially stabilized or complete stable zirconium white in this adulterated four directions transformation toughening and tiny crack toughness reinforcing aspect excellent property, have high room temperature strength and fracture toughness property.Studies show that in recent years, with the tetragonal phase zirconium oxide (Y-TZP) of stabilized with yttrium oxide, when crystal size is controlled at nano level (less than 100nm), the sudden change that may bring material property, as significantly improving of the strength of materials and fracture toughness property, the superplasticity under the realization normal temperature etc.Simultaneously, the zirconium white of stabilized with yttrium oxide still is a kind of good gas sensitive (being used for oxygen sensor) and solid state battery material, is one of focus of present material area research.
Utilize the character of nano zirconium oxide powder, it is better or possess the matrix material and the functional materials of some specific function to work out mechanical property, is applied to different fields, is the final purpose of preparation Zirconium powder research work.One of main prerequisite that improves the zircite product performance is requirement crystal size tiny (nano level), even particle size distribution, the purity height of preparing Zirconium powder, it is few to reunite, and the cost of preparation low, be easy to suitability for industrialized production.
The method for preparing at present nano zirconium oxide powder is divided liquid phase method and vapor phase process.Wherein liquid phase method has coprecipitation method, hydrothermal method, sol-gel method, microemulsion method etc.These methods respectively have its characteristics, but also exist a lot of not enough.Be in the solution that contains zirconates (as zirconium oxychloride, zirconium sulfate, zirconium carbonate acyl etc.), to add precipitation agent as coprecipitation method, obtain precipitation of hydroxide, more after filtration, washing, dehydration, dry, calcining, obtain Zirconium powder.This method is relatively simple, can make that granularity is little, the more manageable multicomponent nanocomposite powder of composition, and JP96000698 has the report of this respect.Weak point is that the powder that makes often exists more hard agglomeration, influences the sintering temperature and the mechanical property of goods.CN1253120A is raw material with the zirconium oxychloride, in order to solve the agglomeration traits of powder, adopts to add dispersion agent and controlled temperature aged method in ethanol, has prepared the nano zirconium oxide powder of able to sinter at low temp.The Hydrothermal Preparation nano zircite is a raw material with the inorganic or organic compound of zirconium generally, can make that particle diameter is little, the powder of high dispersive, and CN1253119A has introduced the method for Hydrothermal Preparation nano zircite colloidal sol.The weak point of hydrothermal method is that preparation condition is harsh, and cost is higher, and output is lower.Sol-gel processing and alkoxide hydrolysis use the organic compound of zirconium, exist the raw material sources difficulty equally, and price is higher, and hydrolysis method long reaction time, productive rate be low excessively, be difficult to defective such as suitability for industrialized production.Vapor phase process is produced nano zirconium oxide powder, and products therefrom is better dispersed, can prepare continuously.But vapor phase process is not suitable for preparation multicomponent mixture oxide powder, and the controllability of component is also relatively poor relatively, and employed cost of material is higher, and output is lower.Is raw material as CN1259488A with the zirconium tetrachloride, mixes, hydrolysis the preparation nano zirconium oxide powder in high-temperature reactor with water vapour.But, obtain the mutually stable Zirconium powder in four directions in this way, the pure zirconia powder that also needs vapor phase process is obtained immerses in the metal salt solution, evaporation, dry, calcining.
Goal of the invention
The preparation method who the purpose of this invention is to provide a kind of nano zirconium oxide powder overcomes the deficiency that exists among the present nano zirconium oxide powder liquid phase method preparation technology, has the reaction times weak point, flow process is few, turnout is safe greatly, but suitability for industrialized production reduces the advantage of preparation cost greatly.
Technical scheme
Technical scheme of the present invention is: the preparation method of nano zirconium oxide powder, in containing the aqueous solution of zirconates, add alkaline precipitating agent, obtain precipitation of hydroxide, washing more after filtration,, dehydration, dry, calcining, obtain Zirconium powder, it is characterized in that adopting the colloidal solution after azeotropic distn dewaters dry in water distilling apparatus, constantly stir when dehydration and drying.This scheme can overcome prior art dries with baking oven or microwave oven, and when sediment separate out and alcohol, what the alcohol of evaporation caused when fractional dose was big catches fire and explode.Simultaneously, can reduce operation steps and program.Thereby can carry out large batch of suitability for industrialized production, can produce more than 10 kilograms at least for every batch.
The preparation method of aforesaid nano zirconium oxide powder is characterized in that adding alcohol earlier in containing the aqueous solution of zirconates, mixes the back and adds alkaline precipitating agent at once.With this pure dispersing method sedimentary agglomeration is improved, and be saved time, enhance productivity.
The preparation method of aforesaid nano zirconium oxide powder is characterized in that the aqueous solution that contains zirconates is, selecting cheap zircon sand for use is raw material, adopt the caustic alkali melting method through roasting, embathe, leaching, purging by crystallization and obtain.With zircon sand is that raw material is directly produced the precursor solution that contains zirconium ion, with be that raw material is produced the precursor solution that contains zirconium ion and compared with the zirconium oxychloride of crystal attitude or other zirconates, can save step that makes zirconates crystal attitude and the step that is returned as the solion attitude from the crystal attitude again.
The preparation method of aforesaid nano zirconium oxide powder is characterized in that calcining temperature after the powder for drying is at 650-1000 ℃.Help removing fully the organism in the powder like this, can improve the purity of product.
The preparation method of aforesaid nano zirconium oxide powder is characterized in that used alcohol is butanols, Virahol, primary isoamyl alcohol, propyl alcohol, glycol ether, ethylene glycol, ethanol.
The preparation method of aforesaid nano zirconium oxide powder, it is characterized in that the aqueous solution that contains zirconates in add crystal phase stablizer after, add alkaline precipitating agent again.Can obtain cubic phase crystal stable under the normal temperature.Described stablizer can be yttrium oxide, calcium oxide, magnesium oxide etc.
The preparation method of nano zirconium oxide powder of the present invention, with the zircon sand is that raw material is exemplified below: adopt sodium hydroxide to mix with the zircon sand fine ore, roasting, make zirconium silicate be converted into six side's phase sodium zirconates that can be decomposed by hydrochloric acid, burn till material and wash impurity such as divided silicon, aluminium, sodium with water, use dissolving with hydrochloric acid again, through impurity such as condensing crystal separation of iron, calcium, titaniums, with oxyethane (or polyacrylamide) secondary silica removal, with ketone or amine extractant extraction iron, prepare the precursor solution of highly purified zirconium.This solution is directly used in preparation monocline phase, the four directions is mutually partially stabilized or full stabilized nanoscale Zirconium powder.The mutually partially stabilized or full stabilized nanoscale zirconium white in preparation four directions, the method for employing other oxide stabilizer of doping (yttrium oxide, calcium oxide, magnesium oxide etc.) is mixed with zirconium solution with dissolving with hydrochloric acid (or Yttrium trinitrate is water-soluble) back as yttrium oxide.PH value with the ammoniacal liquor regulator solution under brute force stirs makes zirconium and yttrium form the oxyhydroxide co-precipitation, washes precipitation with water.Precipitation of hydroxide is mixed with alcohol, in the high temperature dehydration moisture eliminator, dewater under certain temperature, calcining obtains nano zirconium oxide powder.This preparation method adopts the azeotropic distn dehydration, utilize the pure oxygen based structures and the hydrophobic grouping of pure molecule, make it to replace the water molecules in the hydroxide colloid, before powder for drying, all remove water molecules wherein, greatly reduce the agglomeration of powder at calcination stage, the nano zirconium oxide powder high dispersing, the agglomeration that obtain are little, have very big specific surface area and sintering activity.This preparation method's key technology is, colloidal solution after the dehydration is dry in water distilling apparatus, constantly stirs when dehydration and drying, and this technology can overcome prior art dries with baking oven or microwave oven, when sediment separate out and alcohol, what the alcohol of evaporation caused when fractional dose was big catches fire and explodes.Simultaneously, can reduce operation steps and program.Thereby can carry out large batch of suitability for industrialized production, can produce more than 10 kilograms at least for every batch.
What above-mentioned preparation method gave an example is described below step by step:
1. zircon sand decomposes.The zircon sand fine ore is mixed by 1: 1.2~1.6 (weight ratios) with sodium hydroxide, and 650 ℃~800 ℃ pyrolytic decompositions are 1.5~3 hours in High Temperature Furnaces Heating Apparatus.
2. the preparation of zirconium precursor liquid solution.Degradation production is through repeatedly washing, filter, separating impurity.
Material after the water washing is controlled salt acidacidity 2.5~4.0 mol through dissolving with hydrochloric acid, and it is 0.1~0.3 grams per liter that adding polyethylene oxide (or polyacrylamide) makes its concentration, and precipitation separation, cooling solution make zirconium with ZrOCl
2The form crystallization.Adopt the method for polyethylene oxide (or polyacrylamide) secondary silica removal and ketone or amine extractant extraction iron to be further purified.ZrOCl
2The water-soluble precursor solution that promptly obtains zirconium.The concentration of zirconium ion is controlled between 0.2~1.0 mol in the solution.
3. precipitate.(doping of controlled oxidation yttrium in Zirconium powder is 2~8mol%) and a certain amount of alcohol to add a certain amount of yttrium solution in the zirconium solution of preparation.Add ammoniacal liquor again, use in the ammoniacal liquor and the generation precipitation of hydroxide.
PH value in the precipitation process is controlled between 9~11, and powerful the stirring, with guarantee the ruthenium ion precipitation fully and with the zirconium hydroxide uniform mixing.
4. solid-liquid separation and washing.Precipitation of hydroxide is adopted the distilled water wash precipitation through centrifugal or press filtration and liquid separation. to remove foreign ion wherein.
5. dehydration.Precipitation of hydroxide after the washing mixes with alcohol, with milling treatment of colloid mixture or powerful the stirring.The add-on of alcohol is 2.0~5.0: 1 with respect to the weight ratio of precipitation of hydroxide.Alcohol herein can be butanols, Virahol, primary isoamyl alcohol, propyl alcohol, glycol ether, ethylene glycol, ethanol.Wherein preferentially adopt butanols and Virahol.
The mixture of oxyhydroxide and alcohol is placed the distillation dehydration drying installation, and heating process temperature is controlled at (pure water azeotropic point temperature) between 70 ℃~180 ℃, with finishing of guaranteeing to react, the water in the precipitation of hydroxide is all removed.
6. dry.After planar water was removed fully, elevated temperature made the alcohol evaporation and collects.Convection drying powder in the distillation dehydration drying installation, the time is 1~5 hour.Constantly stir in the drying process, make the powder drying temperature even.
7. calcining: control calcining temperature between 450-1000 ℃ according to the granularity of required powder, the time is 1-5 hour.The purpose of calcination is that the powder crystallization that drying obtains is become crystalline oxide.
Outstanding feature of the present invention is:
1. the reaction times is short.With the zirconium oxychloride is raw material, and the time that makes nano zirconium oxide powder is no more than 6 hours, is raw material with the zircon sand, and the time that makes nano zirconium oxide powder is no more than 20 hours.
2. the drying treatment amount is big, and is safe, but suitability for industrialized production.When in enormous quantities dry, isolated alcohol can not catch fire and explode, thus can tens, the hundreds of kilogram carry out drying.
3. flow process is few, and equipment is simple, and processing parameter is easy to control, is easy to large-scale industrial production.
4. adopt alcohol to disperse and the azeotropic distn dewatering process, reduced the agglomeration of powder, the gained powder granularity is little, be evenly distributed, pattern is regular, reunion is less.
5. Zhi Bei zirconium white has big specific surface area.
6. adulterated oxide stabilizer can suppress the grain growth in the calcination process effectively.
Be loose shape behind the powder drying that adopts above method to prepare, the granularity of the Zirconium powder after the calcining can be as small as several nanometer to tens nanometers, the less and hard aggregation-free body of reuniting.
The protection domain of present patent application is not subjected to above-mentioned restriction of giving an example.Nano zirconium oxide powder by the preparation of present patent application disclosed method has good performance, thereby important application is arranged in many aspects.For example, utilize its granularity tiny, reunite fewly, can reduce about 300 ℃ of the sintering temperatures of ceramic.Utilize its high strength, high rigidity and toughness, be used to make sintex, bearing, valve, abrasive material.Utilize low, the high temperature resistant and wear resistance of its heat-conduction coefficient, be used for the spraying of plasma body ceramic layer and the high-temperature fuel gas turbine components material of cylinder sleeve of engine.Because the superplasticity that nanometer zirconium oxide ceramic occurs, being desirably in easily processing aspect of ceramic has important application.
In order to be illustrated more clearly in the present invention, enumerate following specific embodiment.
Embodiment 1:
30 kilograms of zirconium oxychlorides getting lenticular are water-soluble, make that zirconium ion concentration is 0.2 mol in the aqueous solution, add the yttrium solution of 0.1 mol, and the doping of controlled oxidation yttrium in Zirconium powder is 3mol%.Add a certain amount of alcohol, Dropwise 5 0% ammoniacal liquor (volume ratio) under brute force stirs, until the pH value of solution value greater than 9.Press filtration separation of hydrogen oxide precipitation, the distilled water wash precipitation is up to detecting less than chlorion (Silver Nitrate check).
The butanols (weight ratio) of precipitation of hydroxide with 2 times mixed, with milling treatment of colloid or powerful the stirring.Place the distillation dehydration drying installation,,, calcined powder 4 hours for 400 ℃ in the High Temperature Furnaces Heating Apparatus until the powder complete drying in 150 ℃ of dehydrations.With the specific surface area of BET method mensuration powder, the granularity of transmissioning electric mirror determining powder, size-grade distribution and crystal morphology, X ray powder crystal diffraction is measured the crystalline structure of powder and the mean particle size of primary particle.The result is as shown in table 1.
Table 1 embodiment 1 obtains the test data of nano zirconium oxide powder
Morphology microstructure four directions phase proportion monocline phase proportion primary particle mean particle size specific surface area (BET)
/% /% /nm /m
2/g
Sub-circular 95 5 5.6 135.2
Embodiment 2:
Get zircon sand fine ore 1000 gram and mix, 700 ℃ of decomposition 1.5 hours in High Temperature Furnaces Heating Apparatus in corundum ware with 1400 gram sodium hydroxide.Degradation production is prepared into 4 liters of solution through washing, dissolving with hydrochloric acid, silica removal, iron, aluminium, sodium etc.The mandelic acid gravimetric determination wherein in the precursor solution of zirconium zirconic concentration be 0.915 mol, the zirconic rate of recovery is 69.4% in the zircon sand.
Add a certain amount of alcohol in the precursor solution of zirconium, powerful Dropwise 5 0% ammoniacal liquor (volume ratio) down that stirs is greater than 9 until the pH value of solution value.The centrifugation precipitation of hydroxide, the distilled water wash precipitation is up to detecting less than chlorion (Silver Nitrate check).
The butanols (weight ratio) of precipitation of hydroxide with 3 times mixed, use milling treatment of colloid.Place distillation drying and dehydrating device,,, calcined powder 2 hours for 650 ℃ in the High Temperature Furnaces Heating Apparatus until the powder complete drying in 150 ℃ of dehydrations.With the specific surface area of BET method mensuration powder, the granularity of transmissioning electric mirror determining powder, size-grade distribution and crystal morphology, X ray powder crystal diffraction is measured the crystalline structure of powder and the mean particle size of primary particle.The result is as shown in table 2.Transmission electron microscope photo is seen Fig. 1.
Table 2 embodiment 2 obtains the test data of nano zirconium oxide powder
Morphology microstructure four directions phase proportion monocline phase proportion primary particle mean particle size specific surface area (BET)
/% /% /nm /m
2/g
Sub-circular 3 97 10.0 90.1
Embodiment 3:
Prepare hydroxide colloid precipitation (doping of yttrium oxide in Zirconium powder is 6mol%) by the method among the embodiment 2.The ethanol (weight ratio) of precipitation of hydroxide with 2 times is mixed, and powerful the stirring.Centrifugation, with the same ethanol repeated washing of measuring once, centrifugation again.Place distillation drying and dehydrating device,,, calcined powder 3 hours for 500 ℃ in the High Temperature Furnaces Heating Apparatus until the powder complete drying in 100 ℃ of dehydrations.With the specific surface area of BET method mensuration powder, the granularity of transmissioning electric mirror determining powder, size-grade distribution and crystal morphology, X ray powder crystal diffraction is measured the crystalline structure of powder and the mean particle size of primary particle.The result is as shown in table 3, and transmission electron microscope is seen Fig. 2.
Table 3 embodiment 3 obtains the test data of nano zirconium oxide powder
Morphology microstructure four directions phase proportion monocline phase proportion primary particle mean particle size specific surface area (BET)
/% /% /nm /m
2/g
Sub-circular 100 0 7.5 110.2
Embodiment 4:
Prepare hydroxide colloid precipitation (doping of yttrium oxide in Zirconium powder is 8mol%) by the method among the embodiment 2.The butanols (weight ratio) of precipitation of hydroxide with 4 times mixed, and powerful the stirring.Centrifugation, with the same butanols repeated washing of measuring once.Place distillation drying and dehydrating device,,, calcined powder 2 hours for 1000 ℃ in the High Temperature Furnaces Heating Apparatus until the powder complete drying in 120 ℃ of dehydrations.The granularity of transmissioning electric mirror determining powder is 43nm, and the crystalline structure that X ray powder crystal diffraction is measured powder is cubic phase.Purity is that zirconium white (hafnium, yttrium) is greater than 99.9%.