CN102220038A - [Alpha]-alumina single-crystal slices, and preparation method thereof - Google Patents
[Alpha]-alumina single-crystal slices, and preparation method thereof Download PDFInfo
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- CN102220038A CN102220038A CN201110097497XA CN201110097497A CN102220038A CN 102220038 A CN102220038 A CN 102220038A CN 201110097497X A CN201110097497X A CN 201110097497XA CN 201110097497 A CN201110097497 A CN 201110097497A CN 102220038 A CN102220038 A CN 102220038A
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Abstract
The invention relates to [alpha]-alumina single-crystal slices, and a preparation method thereof. The [alpha]-alumina single-crystal slices are characterized in that: the slices are composed of a main component of alumina and an auxiliary component of calcium oxide, wherein the weight of the calcium oxide in the [alpha]-alumina single-crystal slices equals 0.5% to 5% of the weight of alumina in the [alpha]-alumina single-crystal slices. The preparation method is that: a solution containing water-soluble aluminum precursor, calcium precursor and water-soluble flux is mixed with an alkali solution containing alkali phosphate; the mixture is then hydrolyzed to form a mixed gel; the gel is then processed through drying and calcining, such that a finish product is obtained. The [alpha]-alumina single-crystal slices have particle sizes greater than or equal to 20 [mu]m, and are well distributed; the thicknesses of the [alpha]-alumina single-crystal slices are small (which are smaller than or equal to 0.5 [mu]m) and are uniform; and the radius-thickness ratios of the [alpha]-alumina single-crystal slices are large (which are greater than or equal to 80). The appearances of the slices are structured, the surfaces of the slices are smooth, and the slices are rarely inlayed, interlaced or laminated. With good dispersity, the [alpha]-alumina single-crystal slices can be applied in the manufacturing of high performance pearlescent pigments, and are especially suitable in the manufacturing of optically variable pigments.
Description
Technical field
The present invention relates to a kind of Alpha-alumina single-chip and preparation method thereof.This Alpha-alumina single-chip is applicable to makes the high-performance pearly pigment, is particularly useful for making pigment changeable colors along with angle.
Background technology
The high-performance pearly pigment is to prepare by the metal oxide (as titanium oxide, ferric oxide etc.) that has high refractive index in high-quality flat substrates coated with uniform.Pigment changeable colors along with angle then is to make at metal oxide and the external protection that high-quality flat substrates surface alternately coats different refractivity by physics or chemical method.What be suitable as high-performance pearly pigment and pigment changeable colors along with angle base material is natural or the laminar material of synthetic.Natural base material commonly used then comprises synthetic mica, flake ferric oxide, sheet silicon oxide, tabular alumina, glass microplate etc. for refining sheet mica, artificial base material.
High-performance pearly pigment and pigment changeable colors along with angle are close to harsh to substrate requirements.At first, substrate surface must be very smooth slick.For the high-performance pearly pigment, if substrate surface is rough, scattering can take place on the surface in most of light, is difficult to obtain the pearliness of high saturation and high brightness; And concerning pigment changeable colors along with angle, have only substrate surface very smooth smooth, accurately the thickness of each coating layer of control obtains perfect optical effect.Secondly, base material must have bigger particle diameter, and is evenly distributed.The base material that particle diameter is less, radius-thickness ratio is inevitable lower, and part light has reduced the parallel light intensity that reflects at generation scattering of base material edge or diffraction between the base material upper and lower surface, and then destroyed the interference of light effect, the saturation ratio of gained pearly pigment and brightness are reduced.Because light is directly different with the ratio of the reflection of small pieces footpath substrate surface and transmission at sheet, if particle diameter is inhomogeneous again, and the tone of interference color just can be different, so particle diameter evenly is the prerequisites that produce bright-coloured and consistent interference color.The 3rd, base material must have bigger radius-thickness ratio.The base material of big radius-thickness ratio, very few at the light proportion of generation scattering of base material edge or diffraction, interference effect is remarkable.Simultaneously, according to the film interference principle, the twice of base material geometric thickness must be within visible wavelength range, that is to say that the base material geometric thickness should be below 0.4 μ m, and Bao Yuehao more, but if be lower than 0.2 μ m, the physical strength of base material reduces, and is easily cracked in subsequent processes.The 4th, base material must have regular pattern.On the one hand, the less scattering of light of base material and the diffraction that have regular pattern; On the other hand, the base material physical strength with regular pattern is higher, can be kept perfectly in repeatedly coating process; Simultaneously, regular base material obtains regular pigment flakes, and regular pigment flakes is easy to orientations in applying operation, increases the smooth finish of coating.The 5th, base material must be easy to disperse less reunion and stacked.Base material is difficult to obtain various bright-coloured interference color if reunion and stacked is arranged, and it is very coarse that coating also can seem.
Natural and the artificial base material that meets above-mentioned requirements fully is very rare, and the base material that successfully is used to prepare high-performance pearly pigment and pigment changeable colors along with angle up to now has: meagre of refined natural sheet mica, synthetic mica, flake ferric oxide, sheet silicon oxide, tabular alumina, glass etc.Wherein, tabular alumina also has following unique advantage except might satisfying above prerequisite: 1, good weatherability.Acidproof, alkaline-resisting, can be under extreme weather conditions or under the particular surroundings normally use; 2, physical strength height.Tabular alumina is the Alpha-alumina single-chip, and the hardness height is not easily broken in subsequent processes.3, water white transparency, specific refractory power is lower.Have more light to participate in interference effect, interference color saturation ratio and brightness are higher.
Tabular alumina is (as open in the open No.39362/1992 of Japanese Patent) with Hydrothermal Preparation at first, but the tabular alumina particle diameter of this method preparation is too little, and radius-thickness ratio is too small, easily reunites and forms twin, is not suitable for use in the pearly pigment substrate.And this method under high pressure carries out, and needs expensive high-pressure reactor, and certain danger is arranged.
Recently, inventors update preparation method and processing condition, prepare suitable flake aluminum oxide as the pearly pigment substrate by using titanium oxide, zinc oxide or stannic oxide as additive, and the exemplary of Ti Chuing provides as follows up to now:
Flake aluminum oxide is made up of aluminum oxide (principal constituent) and titanium oxide (auxilliary composition), median size 5-60 μ m, and thickness is less than 1 μ m, and radius-thickness ratio is greater than 20.(the open CN 1150165A of Chinese patent).
The flaky alpha-alumina crystal of large aspect ratio is made up of aluminum oxide, zinc oxide and stannic oxide, and average particle thickness is smaller or equal to 0.5 μ m, and the average grain chi is more than or equal to 30 μ m, and aspect ratio is more than or equal to 100.(the open CN101541681A of Chinese patent).
The flake aluminum oxide of foregoing invention can be used to prepare pearly pigment, but still is unsuitable for preparing high-performance pearly pigment, especially pigment changeable colors along with angle.Their defective is mainly reflected in the following aspects:
1, the alumina wafer of above-mentioned each invention is difficult to all satisfy the various prerequisites of above-mentioned high-performance pearly pigment and pigment changeable colors along with angle base material.The flaky alpha-alumina crystal thickness that the method for interpolation titanium oxide obtains is than higher, and density is bigger, is difficult to form even metal or metal oxide coating layer in the above.Add the flaky alpha-alumina crystal that the method for zinc oxide and stannic oxide obtains simultaneously, although thinner, median size is bigger, and size distribution is even inadequately, influences the pearl effect of pigment strongly.
2, the difficult dispersion.The alumina wafer of above-mentioned each invention is in process of growth, inlay mutually, interlock, stacked together, form bigger agglomerate, the nucleus of these agglomerates is very fine and close, no matter is to use physics mode, as heating, stirring or ultra-sonic dispersion, or chemical mode, molten as acid, alkali is molten, or dual-purpose dual mode all can't effectively disperse it.The result is, on the one hand a large amount of wafers form can't the dispersive agglomerate, greatly reduces yield, on the other hand, these agglomerates must be separated from product, has increased production link, thereby has improved cost greatly.
3, pattern irregularity, particle diameter is inhomogeneous.Generally speaking, in above-mentioned each invention, if the processing parameter regulation and control are proper, wafer should grow into relatively regular sexangle.But actual in the wafer process of growth because inlay mutually, interlock, stacked together, form bigger agglomerate, must adopt physics or chemical method to disperse.Because wafer is very thin, generally below 0.5 μ m, absolute physical strength is relatively poor, simultaneously inlaying mutually between the wafer, interlock, stacked, must make some defectives of generation on the wafer, as the gap of dislocation, crack, mosaic site etc., in dispersion process, because the effect of external force, wafer is cracked from fault location easily, becomes the small pieces of pattern irregularity.Again because the distribution of defective is at random, the size of external force also can only be controlled within the scope, so the sizableness of wafer is inhomogeneous after disperseing, before carrying out subsequent disposal, must carry out classification, increase production link equally, improve cost, limited the scope of application of product, reduced its competitive power as high-performance pearly pigment and pigment changeable colors along with angle base material.
Summary of the invention
At the defective that exists in the above-mentioned prior art, one of technical problem to be solved by this invention provides that a kind of pattern is regular, particle diameter is big and be evenly distributed, radius-thickness ratio is big, good dispersity, suitable Alpha-alumina single-chip as high-performance pearly pigment and pigment changeable colors along with angle base material.
Two of technical problem to be solved by this invention provides a kind of preparation method of above-mentioned Alpha-alumina single-chip.
The invention discloses a kind of new Alpha-alumina single-chip, it is made up of aluminum oxide (principal constituent) and calcium oxide (auxilliary composition), its preparation method is: the solution that will contain water-soluble flux, calcium precursor and aluminum precursor under selected condition mixes with the alkaline aqueous solution that contains phosphoric acid salt or pyrophosphate salt, hydrolysis forms mixed gel, drying, calcination processing and obtaining.
A first aspect of the present invention relates to a kind of Alpha-alumina single-chip, it is characterized in that: it is made up of principal constituent aluminum oxide and auxilliary composition calcium oxide, and the weight of calcium oxide is the 0.5%-5% of alumina weight.
A second aspect of the present invention relates to the preparation method of above-mentioned Alpha-alumina single-chip, may further comprise the steps:
(1) preparation contains the mixing precursor solution of water-soluble aluminum precursor, calcium precursor and water-soluble flux, and wherein the calcium precursor is counted the 0.5%-5% of aluminum precursor with aluminum oxide weight in calcium oxide;
(2) alkaline aqueous solution that will contain alkali metal phosphate joins in the described mixing precursor solution of step (1), and whole pH was 6.0-8.0 when the control hydrolysis reaction finished, and obtained containing the mixed gel of hydrolysate, and the weight of described alkali metal phosphate is with P
2O
5Count the 0.1-1% of water-soluble aluminum precursor in aluminum oxide weight;
(3) at 60-150 ℃ of dry mixed gel;
(4) under 900-1300 ℃, make exsiccant mixed gel calcining contain the block mixture of Alpha-alumina single-chip and fusing assistant in 1-6 hour with preparation;
(5) described block mixture is cooled to room temperature, cleans water-soluble flux, dry to obtain the Alpha-alumina single-chip.
Below be to specific descriptions of the present invention.
The present invention is mainly reflected in the new Alpha-alumina single-chip that contains calcium oxide.With contain titanium oxide or contain zinc oxide or the laminar alpha-alumina crystal that not only contained zinc oxide but also contained stannic oxide is compared, calcium oxide can more effectively promote reducing of grain thickness and platy shaped particle at diametric ordering growth, and can effectively prevent particle agglomeration.Alpha-alumina single-chip provided by the invention has and is less than or equal to 0.5 μ m, the mean thickness of preferred 0.1-0.3 μ m; More than or equal to 20 μ m, the median size of preferred 25-50 μ m; Be equal to or greater than 80, the radius-thickness ratio of preferred 100-200.In addition, its profile is more regular, and the surface is very smooth, and water white transparency is seldom inlayed between the wafer, staggered and stacked, good dispersity.Therefore Alpha-alumina single-chip of the present invention is particularly suitable for as high-performance pearly pigment and pigment changeable colors along with angle base material.
To explain the preparation method of Alpha-alumina single-chip of the present invention in detail below.
At first, a kind of aqueous solution that contains water-soluble aluminum precursor, calcium precursor and water-soluble flux of preparation.
The example of water-soluble aluminum precursor includes but not limited to the oxysalt of aluminium, the halogenide of aluminium and the oxide compound of aluminium, wherein is preferably Tai-Ace S 150 and aluminum nitrate.Because they are easy to obtain and use.
The example of water-soluble calcium precursor includes but not limited to the oxysalt of calcium, the halogenide of calcium and the oxide compound of calcium, and wherein preferably calcium chloride and nitrocalcite are because they are soluble in water.Calcium chloride is stable in the fused salt treating processes, exists with calcium ion in fused salt, and nitrocalcite can decomposition produce into calcium oxide more than 500 ℃.And no matter whether decompose, in recrystallization process, calcium ion or calcium oxide are attached to the alpha-alumina crystal surface, stoped inlaying mutually between the alpha-alumina crystal, staggered and stacked, the more important thing is, at high temperature calcium ion replaces aluminum ion by diffusing into the aluminum oxide intracell, suppressed the growth of higher (0001) crystal face of surface energy, promoted the growth of surface energy lower (2110), (1120), (1210) crystal face simultaneously, thereby it is less to prepare thickness, the uniform Alpha-alumina single-chip of particle diameter.In addition, by changing the consumption of calcium salt, gained Alpha-alumina single-chip has different thickness and particle diameter, so radius-thickness ratio also is adjustable.
The amount of calcium precursor is decided with the requirement (particle diameter, thickness and radius-thickness ratio etc.) of product, usually the calcium precursor with calcium oxide count into; Between the 0.5-5wt% of aluminum precursor with alumina content, preferred 1-3wt%.The amount of calcium salt is during less than 0.5wt%, is difficult to stop alpha-alumina crystal to form twin and reunites mutually.And the amount of calcium salt can stop the formation of Alpha-alumina single-chip during greater than 5wt%.
The example of water-soluble flux comprises various alkali metal sulfates or muriate, and sodium-chlor is particularly arranged, sodium sulfate, and Repone K, vitriolate of tartar, lithium chloride, Lithium Sulphate both can be wherein a kind of, also can be wherein several mixtures.The mol ratio of aluminum precursor and water-soluble flux is 1: 1-8.When mol ratio was higher than 1: 1, alpha-alumina crystal was difficult to be dissolved in fully in the melting salt, and the formation of Alpha-alumina single-chip is difficulty very.And when mol ratio is lower than 1: 8, can't obtain special effect, but can waste a large amount of fusing assistants, and need a large amount of water that it is removed.
Second step, a kind of alkaline aqueous solution that contains phosphoric acid salt or pyrophosphate salt is added drop-wise in the above-mentioned aqueous solution that contains water-soluble aluminum precursor, calcium precursor and water-soluble flux, whole pH is 6.0-8.0 when hydrolysis reaction finishes, and obtains a kind of mixed gel that contains hydrolysate.
The example of phosphoric acid salt or pyrophosphate salt comprises sodium phosphate, sodium hydrogen phosphate, Sodium phosphate dibasic, potassiumphosphate, potassium hydrogen phosphate, dipotassium hydrogen phosphate, trisodium phosphate, potassium pyrophosphate.It is the slowest that phosphate anion is easy to be adsorbed in the alpha-alumina crystal speed of growth, and the most normal (0001) crystal face that appears has stoped the stack of growth unit on crystal face, has played the effect of prohibiting, and aluminum oxide is restricted in the growth of thickness direction.When its amount during, do not have the effect that reduces alpha-alumina crystal thickness less than the 0.1wt% of alumina content.When its amount during greater than the 1wt% of alumina content, alpha-alumina crystal is because too thin cracked easily, and obtains the little and uneven product of particle diameter.
The example of alkali comprises yellow soda ash, salt of wormwood, sodium hydroxide, potassium hydroxide, sodium bicarbonate, saleratus.Wherein be preferably yellow soda ash and salt of wormwood.Its amount is approximately suitable with the chemical equivalent that neutralizes and hydrolysis water dissolubility aluminum precursor is required.
In the 3rd step, mixed gel was descended dry 3-24 hour at 60-150 ℃.If temperature is lower than 60 ℃, mixed gel can't complete drying, can not carry out fused salt and handle.If temperature is higher than 150 ℃, the surface of mixed gel forms duricrust, causes the skewness of fusing assistant in xerogel, causes the formation of inhomogeneous Alpha-alumina single-chip.
In the 4th step, the exsiccant mixed gel was calcined 1-6 hour down at 900-1300 ℃.When temperature is lower than 900 ℃, there is not laminar alpha-alumina crystal to form.And when temperature is higher than 1300 ℃, can decompose as the vitriol of solubility promoter, fusing assistant is reduced in a large number, thereby cause wafer to be reunited together, make follow-up dispersion process difficult unusually; Simultaneously, temperature is too high, and energy consumption increases, and the performance of product does not but almost change.
The 5th step, with the cooling of gained block mixture, clean water-soluble solubility promoter, drying makes the Alpha-alumina single-chip.
The XRD diffracting spectrum of Alpha-alumina single-chip provided by the invention shows: have only the diffraction peak of Alpha-alumina in the XRD diffracting spectrum, this shows that calcium ion replaces the crystalline network that some aluminum ion has entered aluminum oxide.And show by chemical analysis, calcium contents in this Alpha-alumina single-chip and the calcium contents in the raw material are about equally, and do not detect the existence of phosphoric, final separated the coming out of this explanation used phosphorus compound in preparation Alpha-alumina single-chip process, calcium cpd then finally becomes the part of Alpha-alumina single-chip of the present invention.
Therefore, the Alpha-alumina single-chip of the present invention's definition is made up of Alpha-alumina (as principal constituent) and calcium oxide (as auxilliary composition).
Beneficial effect of the present invention: Alpha-alumina single-chip particle diameter provided by the invention 〉=20 μ m and being evenly distributed; Thickness little (≤0.5 μ m) and distribution homogeneous, radius-thickness ratio big (〉=80), pattern is more regular, and smooth surface is seldom inlayed between the wafer, staggered and stacked, good dispersity.
Description of drawings
Fig. 1 is the X-ray diffracting spectrum of the Alpha-alumina single-chip that makes of embodiment 1.
Fig. 2 is the sem photograph of the Alpha-alumina single-chip that makes of embodiment 1.
Embodiment
In order to further specify the present invention, provide the following example.These embodiment just illustrate of the present invention, are not the restrictions to protection domain of the presently claimed invention.
Embodiment 1
1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 458g anhydrous sodium sulphate (Na
2SO
4), 375g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.Calcium Chloride Powder Anhydrous (the CaCl that in the solution that obtains, adds 7.7g 35%
2) solution, stir.The solution that makes is called the aqueous solution (a).
2) with 3.7g ten phosphate dihydrate sodium (Na
3PO
412H
2O) and 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
3) with mixed gel 70 ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.
4) the exsiccant mixed gel is pulverized, the corundum crucible of packing into is incubated 6 hours down at 1200 ℃.
5) will cool off crucible to room temperature, and add 70 ℃ hot water, supersound process then with the dissolving fusing assistant, and is separated the Alpha-alumina single-chip, leaches insoluble solids, with the deionized water repetitive scrubbing to specific conductivity less than 20 μ Scm
-1, dry then, just obtain required Alpha-alumina single-chip.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffracting spectrum, and this explanation calcium ion replaces the crystalline network that some aluminum ion has entered aluminum oxide, sees Fig. 1.Atom analysis shows that the Alpha-alumina single-chip contains the calcium oxide of 0.9% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation (sem photograph is seen Fig. 2) shows that gained Alpha-alumina single-chip particle diameter is 20-35 μ m, and thickness is about 0.3 μ m, does not have twin and reunion.During dispersed with stirring, this Alpha-alumina single-chip produces the smooth streamline with strong metalluster, has shown its good dispersion in water in water.
Embodiment 2
Water-soluble liquid calcium precursor uses the anhydrous chlorides of rase calcium solution of 15.4g 35% among this embodiment, and other condition is all identical with embodiment 1 with method.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffracting spectrum, and this explanation calcium ion replaces the crystalline network that some aluminum ion has entered aluminum oxide.Atom analysis shows that the Alpha-alumina single-chip contains the calcium oxide of 1.8% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that gained Alpha-alumina single-chip particle diameter is 25-40 μ m, and thickness is about 0.3 μ m, does not have twin and reunion.During dispersed with stirring, the Alpha-alumina single-chip produces the smooth streamline with strong metalluster, has shown its good dispersion in water in water.
Water-soluble liquid calcium precursor uses the anhydrous chlorides of rase calcium solution of 23.1g 35% among this embodiment, and other condition is all identical with embodiment 1 with method.
Confirm to have only the diffraction peak of Alpha-alumina in the diffracting spectrum through the X-ray diffraction analysis.Atom analysis shows that the Alpha-alumina single-chip contains the calcium oxide of 2.7% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that gained Alpha-alumina single-chip particle diameter is 30-45 μ m, and thickness is about 0.3 μ m, does not have twin and reunion.During dispersed with stirring, the Alpha-alumina single-chip produces the smooth streamline with strong metalluster, has shown its good dispersion in water in water.
Embodiment 4
Ten phosphate dihydrate sodium (Na among this embodiment
3PO
412H
2O) be 7.4g, other condition is all identical with embodiment 1 with method.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffracting spectrum.Atom analysis shows that the Alpha-alumina single-chip contains the calcium oxide of 0.9% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that gained Alpha-alumina single-chip particle diameter is 30-45 μ m, and thickness is about 0.2 μ m, does not have twin and reunion.During dispersed with stirring, the Alpha-alumina single-chip produces the smooth streamline with strong metalluster, has shown its good dispersion in water in water.
The water-soluble calcium precursor uses the anhydrous chlorides of rase calcium solution of 3.8g 35% among this embodiment, and other condition is all identical with embodiment 1 with method.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffracting spectrum.Atom analysis shows that the Alpha-alumina single-chip contains the calcium oxide of 0.4% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that gained Alpha-alumina single-chip particle diameter is 15-30 μ m, and thickness is about 0.3 μ m, does not have twin and reunion.During dispersed with stirring, the Alpha-alumina single-chip produces the smooth streamline with strong metalluster, has shown its good dispersion in water in water.
Embodiment 6
1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 114.5 anhydrous sodium sulphate (Na
2SO
4), 93.8g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.Calcium Chloride Powder Anhydrous (the CaCl that in the solution that obtains, adds 38.5g 35%
2) solution, stir.The solution that makes is called the aqueous solution (a).
2) with 0.74g ten phosphate dihydrate sodium (Na
3PO
412H
2O) and 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
3) with mixed gel 70 ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.
4) the exsiccant mixed gel is pulverized, the corundum crucible of packing into is incubated 6 hours down at 1300 ℃.
5) will cool off crucible to room temperature, clean water-soluble solubility promoter, dry then, just obtain required Alpha-alumina single-chip.
Embodiment 7
1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 916g anhydrous sodium sulphate (Na
2SO
4), 750g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.Calcium Chloride Powder Anhydrous (the CaCl that in the solution that obtains, adds 7.7g 35%
2) solution, stir.The solution that makes is called the aqueous solution (a).
2) with 3.7g ten phosphate dihydrate sodium (Na
3PO
412H
2O) and 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
3) with mixed gel 70 ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.
4) the exsiccant mixed gel is pulverized, the corundum crucible of packing into is incubated 6 hours down at 900 ℃.
5) will cool off crucible to room temperature, and add 70 ℃ hot water, supersound process then with the dissolving fusing assistant, and is separated the Alpha-alumina single-chip, leaches insoluble solids, with the deionized water repetitive scrubbing to specific conductivity less than 20 μ Scm
-1, dry then, just obtain required Alpha-alumina single-chip.
Embodiment 8
1) with 358.2g aluminum chloride (AlCl
3), 188.6g sodium-chlor (NaCl), 160.4g Repone K (KCl) joins in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.In the solution that obtains, add 5.7g four water-calcium nitrate (Ca (NO
3)
24H
2O) solution stirs.The solution that makes is called the aqueous solution (a).
2) with 1.6g potassium pyrophosphate (K
4P
2O
7) and 426.8g anhydrous sodium carbonate (106) (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
3) with mixed gel 70 ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.
4) the exsiccant mixed gel is pulverized, the corundum crucible of packing into is incubated 6 hours down at 1200 ℃.
5) will cool off crucible to room temperature, and add 70 ℃ hot water, supersound process then with the dissolving fusing assistant, and is separated the Alpha-alumina single-chip, leaches insoluble solids, with the deionized water repetitive scrubbing to specific conductivity less than 20 μ Scm
-1, dry then, just obtain required Alpha-alumina single-chip.
Embodiment 9
1) with 137g aluminum oxide (Al
2O
3), 188.6g sodium-chlor (NaCl), 275.3g sulfuric acid monohydrate lithium (Li
2SO
4H
2O) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.In the solution that obtains, add 1.36g calcium oxide (CaO), stir.The solution that makes is called the aqueous solution (a).
2) with 3.5g disodium hydrogen phosphate (Na
2HPO
412H
2O) and 426.8g anhydrous sodium carbonate (106) (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
3) with mixed gel 70 ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.
4) the exsiccant mixed gel is pulverized, the corundum crucible of packing into is incubated 6 hours down at 1200 ℃.
5) will cool off crucible to room temperature, and add 70 ℃ hot water, supersound process then with the dissolving fusing assistant, and is separated the Alpha-alumina single-chip, leaches insoluble solids, with the deionized water repetitive scrubbing to specific conductivity less than 20 μ Scm
-1, dry then, just obtain required Alpha-alumina single-chip.
The comparative example 1
(1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 458g anhydrous sodium sulphate (Na
2SO
4), 375g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (a).
(2) with 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
(3) with mixed gel 70 ℃ of following ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.The exsiccant mixed gel is pulverized, and the corundum crucible of packing into was handled 6 hours at 1200 ℃ of following fused salts.
(4) the cooling crucible adds 70 ℃ hot water to room temperature, supersound process then, and dissolving fusing assistant, and with laminar alpha-alumina crystal separation.Leach insoluble solids, use deionized water wash, dry then, obtain alpha-alumina powder.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffraction pattern.The result of opticmicroscope and scanning electron microscopic observation shows that Alpha-alumina is the particulate state crystal, obviously has twin and reunion, does not obtain the Alpha-alumina single-chip.In water, during dispersed with stirring, obtain muddy suspension, do not produce any streamline.
The comparative example 2
(1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 458g anhydrous sodium sulphate (Na
2SO
4), 375g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.Calcium Chloride Powder Anhydrous (the CaCl that in the solution that obtains, adds 7.7g 35%
2) solution, stir.The solution that makes is called the aqueous solution (a).
(2) with 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
(3) with mixed gel 70 ℃ of following ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.The exsiccant mixed gel is pulverized, and the corundum crucible of packing into was handled 6 hours at 1200 ℃ of following fused salts.
(4) the cooling crucible adds 70 ℃ hot water to room temperature, supersound process then, and dissolving fusing assistant, and with laminar alpha-alumina crystal separation.Leach insoluble solids, use deionized water wash, dry then, obtain alpha-alumina powder.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffraction pattern.Atom analysis shows that the alpha-alumina crystal powder contains the calcium oxide of 0.9% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that Alpha-alumina is the particulate state crystal, and particle diameter is 5-10 μ m, and thickness surpasses 1 μ m, obviously greater than by adding the Alpha-alumina single-chip that phosphorus compound makes, causes radius-thickness ratio very little (below 10).In water, during dispersed with stirring, obtain muddy suspension, do not produce any streamline.
The comparative example 3
(1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 458g anhydrous sodium sulphate (Na
2SO
4), 375g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (a).
(2) with 3.7g ten phosphate dihydrate sodium (Na
3PO
412H
2O) and 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
(3) with mixed gel 70 ℃ of following ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.The exsiccant mixed gel is pulverized, and the corundum crucible of packing into was handled 6 hours at 1200 ℃ of following fused salts.
(4) the cooling crucible adds 70 ℃ hot water to room temperature, supersound process then, and dissolving fusing assistant, and with laminar alpha-alumina crystal separation.Leach insoluble solids, use deionized water wash, dry then, obtain alpha-alumina powder.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffraction pattern.The result of opticmicroscope and scanning electron microscopic observation shows that Alpha-alumina is the particulate state crystal.In water, during dispersed with stirring, obtain muddy suspension, do not produce any streamline.
The comparative example 4
(1) with 895.2g 18 water Tai-Ace S 150 (Al
2(SO
4)
318H
2O), 458g anhydrous sodium sulphate (Na
2SO
4), 375g anhydrous potassium sulfate (K
2SO
4) join in the deionized water of 1800ml, be heated to 70 ℃ and make it to dissolve fully.Add the calcium chloride solution of 38.5g 35% in the solution that obtains, the solution that makes is called the aqueous solution (a).
(2) with 18.5g ten phosphate dihydrate sodium (Na
3PO
412H
2O) and 426.8g anhydrous sodium carbonate (Na
2CO
3) join in the deionized water of 1000ml, be heated to 70 ℃ and make it to dissolve fully.The solution that makes is called the aqueous solution (b).When constantly stirring, with 50ml/ minute speed the aqueous solution (b) is added drop-wise in the aqueous solution (a), after dropwising, continue to stir 10 minutes, make to react completely, make a kind of mixed gel that contains fusing assistant.
(3) with mixed gel 70 ℃ of following ℃ of ageings 10 hours, 60 ℃ of following vacuum-dryings, and then 105 ℃ dry 10 hours down.The exsiccant mixed gel is pulverized, and the corundum crucible of packing into was handled 6 hours at 1200 ℃ of following fused salts.
(4) the cooling crucible adds 70 ℃ hot water to room temperature, supersound process then, and dissolving fusing assistant, and with laminar alpha-alumina crystal separation.Leach insoluble solids, use deionized water wash, dry then, obtain alpha-alumina powder.
The X-ray diffraction analysis confirms to have only the diffraction peak of Alpha-alumina in the diffraction pattern.Atom analysis shows that laminar alpha-alumina crystal contains the calcium oxide of 4.6% (weight ratio).The result of opticmicroscope and scanning electron microscopic observation shows that Alpha-alumina is the particulate state crystal, does not obtain the Alpha-alumina single-chip.In water, during dispersed with stirring, obtain muddy suspension, do not produce any streamline.
Table 1 has been listed the used condition of method among embodiment 1-9 and the comparative example 1-4.Table 2 has been listed the pattern of the alpha-alumina crystal that makes among embodiment 1-5 and the comparative example 1-4.
Each concrete raw material that the present invention is cited, and the bound of each raw material, interval value, and the bound of processing parameter (as temperature, time etc.), interval value can both realize the present invention, do not enumerate embodiment one by one at this.
Table 1
Table 2
Claims (9)
1. Alpha-alumina single-chip, it is characterized in that: it is made up of principal constituent aluminum oxide and auxilliary composition calcium oxide, and the weight of calcium oxide is the 0.5%-5% of alumina weight in the described Alpha-alumina single-chip.
2. Alpha-alumina single-chip according to claim 1 is characterized in that: described Alpha-alumina single-chip thickness≤0.5 μ m, and particle diameter 〉=20 μ m, radius-thickness ratio 〉=80, profile is more regular.
3. the preparation method of Alpha-alumina single-chip according to claim 1 is characterized in that, may further comprise the steps:
(1) preparation contains the mixing precursor solution of water-soluble aluminum precursor, calcium precursor and water-soluble flux, and wherein the calcium precursor is the 0.5%-5% of aluminum precursor in aluminum oxide weight in oxide compound weight;
(2) alkaline aqueous solution that will contain alkali metal phosphate joins in the described mixing precursor solution of step (1), and whole pH was 6.0-8.0 when the control hydrolysis reaction finished, and obtained containing the mixed gel of hydrolysate, and the weight of described alkali metal phosphate is with P
2O
5Count the 0.1-1% of water-soluble aluminum precursor in aluminum oxide weight;
(3) at 60-150 ℃ of dry mixed gel;
(4) under 900-1300 ℃, make exsiccant mixed gel calcining contain the block mixture of Alpha-alumina single-chip and fusing assistant in 1-6 hour with preparation;
(5) described block mixture is cooled to room temperature, cleans water-soluble flux, dry to obtain the Alpha-alumina single-chip.
4. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: the mol ratio of described aluminum precursor and water-soluble flux is 1 ︰ 1-8.
5. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: described water-soluble aluminum precursor is selected from the oxysalt of aluminium, the halogenide of aluminium and the oxide compound of aluminium.
6. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: described water-soluble calcium precursor is selected from the oxysalt of calcium, the halogenide of calcium and the oxide compound of calcium.
7. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: described water-soluble flux is one or more the mixture in alkali metal sulfates or the muriate.
8. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: described alkali metal phosphate is selected from one or more in sodium phosphate, sodium hydrogen phosphate, Sodium phosphate dibasic, potassiumphosphate, potassium hydrogen phosphate, dipotassium hydrogen phosphate, trisodium phosphate, the potassium pyrophosphate.
9. the preparation method of Alpha-alumina single-chip according to claim 3 is characterized in that: described alkali is selected from one or more in yellow soda ash, salt of wormwood, sodium hydroxide, potassium hydroxide, sodium bicarbonate, the saleratus.
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