CN103172366B - A kind of preparation method of microwave dielectric ceramic materials - Google Patents
A kind of preparation method of microwave dielectric ceramic materials Download PDFInfo
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Abstract
The invention discloses a kind of preparation method of microwave dielectric ceramic materials, comprising: the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide is carried out mechanical uniform mixing, form powder granule; Powder granule is carried out first time high-energy ball milling, with by even for powder granule refinement, forms refinement powder; Refinement powder is carried out high-temperature calcination in encloses container, forms presoma powder; Presoma powder is carried out second time high-energy ball milling, with by the evenly refinement further of presoma powder, forms ceramic powder.The preparation method of microwave dielectric ceramic materials of the present invention increases Volatile Elements Ca molar percentage in the feed and in conjunction with twice high-energy-milling by appropriate, " the lattice imperfection effect " that Volatile Elements Ca can be suppressed to produce, reduce sintering temperature to a great extent and shorten sintering time, and realize high compaction, reduce production cost and technical difficulty.
Description
Technical field
The present invention relates to stupalith field, particularly relate to a kind of preparation method of microwave dielectric ceramic materials.
Background technology
Microwave-medium ceramics is applicable to the medium dielectric constant microwave medium of microwave frequency band and the stupalith of high quality factor, the functions such as media isolated, Medium Wave Guide and dielectric resonance are played in microwave circuit, can be used for making the microwave hybrid integrated circuit being main composition with microwave tube, pipe racks line etc., reduce quality and the volume of the devices such as microwave dielectric resonator largely.
Wherein, there is (1-x) CaTiO of perovskite structure
3-xNdAlO
3(be called for short CTNA, wherein, x represents molar percentage), base microwave medium ceramic material was owing to having moderate specific inductivity (ε
r~ 45), close to zero temperature coefficient of resonance frequency (τ
fand quite high quality factor (Q × f>30000), thus cause extensive concern and the research of industry ~ 0).But the research of industry mainly rests in the mutual relationship of the microtexture of its material and the dielectric properties of dielectric properties and firing process and material, and the research for its preparation method is little.
In current prior art, the preparation method that domestic and international manufacturer mostly adopts mechanically mixing to be combined with solid state sintering, under high-temperature calcination condition, solid state reaction occur after fully mixing in planetary or stirring ball mill by solid powder raw material and prepare required ceramic powder, and then compression moulding, solid state sintering become medium ceramic material.This traditional preparation method mainly contains following defect: in high-temperature sintering process, powder reactive behavior is poor, needs very high sintering temperature (more than at least 1450 degrees Celsius) and longer sintering time, causes the production energy consumption that needs are high; The ceramic powder particle diameter of Reactive Synthesis is comparatively large, and size-grade distribution is wide, and dephasign is more and then affect the principal crystalline phase purity of CTNA and cause being difficult to realize the complete densification of sintering, is namely difficult to obtain the medium ceramic material possessing and stablize excellent microwave dielectric property; Have ignored the detrimentally affect that volatile " the lattice imperfection effect " in sintering process of Ca element causes the microwave property of product.
Therefore, need the preparation method that a kind of microwave dielectric ceramic materials is provided, prepare in microwave dielectric ceramic materials process that sintering temperature is too high, sintering time is longer and be difficult to realize the problem of sintering densification to solve in prior art.
Summary of the invention
The technical problem that the present invention mainly solves is to provide a kind of preparation method of microwave dielectric ceramic materials, can prepare in microwave dielectric ceramic materials process " the lattice imperfection effect " that reduce sintering temperature, shorten sintering time and suppress Volatile Elements Ca to cause.
For solving the problems of the technologies described above, the invention provides a kind of preparation method of microwave dielectric ceramic materials, comprise: the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide is carried out mechanical uniform mixing, form powder granule, the formula of mixed powder is according to chemical formula (1-x) Ca
1+ytiO
3-x [NdAlO
3] make wherein x and y meet 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% respectively, the purity of described calcium carbonate, calcium oxide and aluminum oxide is all greater than 99.5%, and the purity of described titanium dioxide and Neodymium trioxide is not less than 99.9%, powder granule is carried out first time high-energy ball milling, and with by even for powder granule refinement, form refinement powder, wherein, ratio of grinding media to material is 8:1 ~ 10:1, and Ball-milling Time is 1 ~ 3 hour, and rotating speed is 600 ~ 800 revs/min, refinement powder is carried out high-temperature calcination in encloses container, and form presoma powder, wherein, calcining temperature is 900 ~ 1200 degrees Celsius, and soaking time is 3 ~ 6 hours, presoma powder is carried out second time high-energy ball milling, wherein, ratio of grinding media to material is 10:1 ~ 12:1, Ball-milling Time 1 ~ 3 hour, rotating speed 600 ~ 1000 revs/min, and add property-modifying additive and sintering aid, with by the further evenly refinement of presoma powder, form ceramic powder, wherein, refinement powder granularity after described first time high-energy ball milling is distributed within the scope of 1 ~ 2 μm, the granularity of the ceramic powder after described second time high-energy ball milling is less than 1 μm, described property-modifying additive is CaO, SrO, ZnO, Al2O3, one or more in Nb2O5 and TiO2, described sintering aid is Bi2O3, B2O3, CuO, one or more in V2O5 and BaO,
Mist projection granulating, adds in described ceramic powder that concentration is 5%, mass percent is the polyvinyl alcohol water solution of 5% ~ 10%, described ceramic powder is made the powder granule of the spherical mobility of tool;
Compression moulding, makes the ceramic pressed compact of desired shape by the powder granule of spherical for described tool mobility;
Sintering, carries out stoking by described ceramic pressed compact, forms ceramic blank, and wherein, most high sintering temperature is 1200 ~ 1500 degrees Celsius, and soaking time is 3 ~ 6 hours;
Mechanical workout and sample detection, carry out surface treatment by described ceramic blank and obtain ceramics sample, and measure the dielectric properties index of described ceramics sample;
Described the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide is carried out mechanical uniform mixing, the step forming powder granule comprises:
Described mixed powder is placed in spherical tank, add zirconium dioxide abrading-ball as grinding medium, add dehydrated alcohol or deionized water carries out mechanical uniform mixing as organic solvent, and after the described powder granule of formation, removing organic solvent carries out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight are 1:3:3 and account for 60% ~ 80% of spherical tank volume, and mixing time is 1 ~ 3 hour.
Wherein, ceramic pressed compact carries out two-sided compression moulding by pressing machine in filler mode manually or automatically, or it is shaping to carry out a shot by shot forming technique.
Wherein, in high-temperature calcinations step, encloses container is high-temperature crucible.
Wherein, the mass percent of property-modifying additive is 1% ~ 4% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount, and the mass percent of sintering aid is 0.1% ~ 1% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount.
The invention has the beneficial effects as follows: the situation being different from prior art, the preparation method of microwave dielectric ceramic materials of the present invention is by increasing Volatile Elements Ca Mole percent when twice high-energy ball milling in the feed, can suppress " the lattice imperfection effect " of the volatile generation of Ca element, reduce sintering temperature to a great extent and shorten sintering time, and realize high compaction, reduce production cost and technical difficulty.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings, wherein:
Fig. 1 is the schematic flow sheet of the preparation method of the microwave dielectric ceramic materials of the embodiment of the present invention;
Fig. 2 is in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, uses conventional solid reaction synthesis process in conjunction with high-energy ball-milling process through the first time particle size distribution figure (a) of refinement powder that obtains of high-energy ball milling and use conventional solid reaction synthesis process in conjunction with high-energy ball-milling process and X-ray diffraction (XRD) collection of illustrative plates (b) of microwave-medium ceramics sample that obtains of the preparation method increasing Ca element percentage composition;
Fig. 3 is in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, the microwave-medium ceramics sample using conventional solid reaction synthesis process to obtain in conjunction with the preparation method of high-energy ball-milling process and use conventional solid reaction synthesis process in conjunction with high-energy ball-milling process and scanning electron microscope (SEM) contrast images (a) of the microwave-medium ceramics sample obtained by the appropriate preparation method increasing Ca element percentage composition and (b).
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only a part of embodiment of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Embodiment one
A preparation method for microwave dielectric ceramic materials, its schematic flow sheet as shown in Figure 1, comprising:
Step S101, carries out mechanical uniform mixing by the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide, forms powder granule.
Step S101 comprises and is placed in spherical tank by mixed powder, add zirconium dioxide abrading-ball as grinding medium, add dehydrated alcohol or deionized water carries out mechanical uniform mixing as organic solvent, and after formation powder granule, removing organic solvent carries out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight are 1:3:3 and account for 60% ~ 80% of spherical tank volume, and mixing time is 1 ~ 3 hour.Wherein, the formula of mixed powder is according to chemical formula (1-x) Ca
1+ytiO
3-x [NdAlO
3] make x and y meet 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide) respectively.Wherein, the purity of calcium carbonate, calcium oxide and aluminum oxide is all greater than 99.5%, and the purity of titanium dioxide and Neodymium trioxide is not less than 99.9%.Owing to having calcium carbonate and calcium oxide in raw material, improve the molar percentage of Volatile Elements Ca in CTNA based dielectric material, " the lattice imperfection effect " that Volatile Elements Ca can be suppressed to cause.
Step S102, carries out first time high-energy ball milling by powder granule, with by even for powder granule refinement, forms refinement powder.
In the present embodiment, first time high-energy ball milling is carried out using zirconium dioxide abrading-ball as the grinding medium of high-energy ball milling, make the size-grade distribution of the refinement powder after first time high-energy ball milling within the scope of 1 ~ 2 μm, effectively improve reactive behavior and the contact area of powder granule, and then reach the object reducing calcination reaction synthesis temperature, wherein, ratio of grinding media to material is 8:1 ~ 10:1, Ball-milling Time is 1 ~ 3 hour, and rotating speed is 600 ~ 800 revs/min.
Step S103, carries out high-temperature calcination by refinement powder in encloses container, forms presoma powder.
In the present embodiment, the powder after first time high-energy ball milling is placed in airtight high-temperature crucible, through the presoma powder of pyroreaction synthesis of high purity principal crystalline phase.The processing parameter of high-temperature burning process is: encloses container is high-temperature crucible, and calcining temperature is 900 ~ 1200 degrees Celsius, and soaking time is 3 ~ 6 hours.
Step S104, carries out second time high-energy ball milling by presoma powder, with by the evenly refinement further of presoma powder, forms ceramic powder.
In the present embodiment, using zirconium dioxide abrading-ball as the grinding medium of high-energy ball milling, and interpolation property-modifying additive and sintering aid carry out second time high-energy ball milling further.The granularity controlling the ceramic powder formed is less than 1 μm, and property-modifying additive is CaO, SrO, TiO
2, ZnO, Al
2o
3, Nb
2o
5and Ta
2o
5in one or more, sintering aid is Bi
2o
3, B
2o
3, CuO, V
2o
5and one or more in BaO, the formula of this microwave dielectric ceramic materials is according to chemical formula (1-x) Ca
1+ytiO
3-x [NdAlO
3] make x and y meet 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide) respectively.Wherein, the mass percent of property-modifying additive is 1% ~ 4% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount, and the mass percent of sintering aid is 0.1% ~ 1% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount.Wherein, ratio of grinding media to material is 10:1 ~ 12:1, Ball-milling Time 1 ~ 3 hour, rotating speed 600 ~ 1000 revs/min.
By adding property-modifying additive and sintering aid, ceramic powder can be made to be uniformly distributed further, reducing the porosity between ceramic powder, the object reducing sintering temperature and microwave-medium ceramics sintering densification to a certain extent can be reached.
In addition, in the present embodiment, after ceramic powder is formed, can also be further comprising the steps as required:
Mist projection granulating, adds in ceramic powder that concentration is 5%, mass percent is the polyvinyl alcohol water solution of 5% ~ 10%, ceramic powder is made the powder granule of the spherical mobility of tool, has good mobility to make this powder granule.
Compression moulding, makes the ceramic pressed compact of desired shape by the powder granule of spherical for tool mobility.
In the present embodiment, ceramic pressed compact carries out two-sided compression moulding by pressing machine in filler mode manually or automatically, or it is shaping to carry out a shot by shot forming technique.Wherein, pressing pressure is 80 ~ 120MPa.
Sintering, carries out stoking by ceramic pressed compact, forms ceramic blank, and wherein, most high sintering temperature is 1200 ~ 1500 degrees Celsius, and soaking time is 3 ~ 6 hours.
In the present embodiment, ceramic pressed compact is put into airtight high-temperature resistant aluminium oxide crucible and carry out stoking, in the high temperature period, solid state reaction occurs and generate fine and close ceramic blank.
Mechanical workout and sample detection, carry out surface treatment by ceramic blank and obtain ceramics sample, and measure the dielectric properties index of ceramics sample.
In the present embodiment, the mechanical workout such as grinding, polishing mode can be adopted to carry out surface treatment to ceramic blank, obtain the ceramics sample of desired size, and measure its dielectric properties index with network analyzer: DIELECTRIC CONSTANT ε
r, temperature coefficient of resonance frequency τ
fand quality factor q.
Embodiment two
A preparation method for microwave dielectric ceramic materials, comprising:
Step one, before batching by former for Neodymium trioxide powder 800 degrees Celsius of lower pre-burnings 3 hours, carry out drying to get rid of moisture; According to chemical formula 0.72Ca
1+0.1mol%tiO
3-0.28NdAlO
3proportioning calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide, zirconium dioxide abrading-ball is added as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed in spherical tank and carry out mechanical uniform mixing, and after formation powder granule, removing organic solvent carries out drying treatment, and mixed powder, abrading-ball, solvent (weight) ratio is 1:3:3 and it accounts for 60% ~ 80% of spherical tank volume, and raw material mixing time is 3 hours.
In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.72mol%, and the stoichiometric ratio of aluminum oxide and Neodymium trioxide is 0.28mol%, and the stoichiometric ratio of calcium oxide is 0.1mol%, to increase the percentage composition of Ca element.It should be noted that, the purity of calcium carbonate, calcium oxide and alumina powder is all greater than 99.5%, and the purity of titanium dioxide and Neodymium trioxide powder is not less than 99.9%.
Step 2, with zirconium dioxide abrading-ball for grinding medium, carry out first time high-energy ball milling after powder granule drying step one formed, so that even for powder granule refinement is formed refinement powder.Wherein, High Energy Ball Milling Time is 2 hours, and ratio of grinding media to material is 8:1, and rotating speed is 400 revs/min.
Step 3, by step 2 formed refinement powder be placed in airtight high-temperature crucible, there is through high-temperature calcination Reactive Synthesis the presoma powder of high purity principal crystalline phase.Wherein, calcining temperature is 1000 degrees Celsius, and soaking time is 3 hours.
Step 4, with zirconium dioxide abrading-ball for grinding medium, presoma powder after calcining is carried out the ceramic powder that second time high-energy ball milling obtains further evenly refinement.Wherein, High Energy Ball Milling Time is 1 hour, and ratio of grinding media to material is 10:1, and rotating speed is 1000 revs/min.
Add polyvinyl alcohol (PVA) aqueous solution (concentration is 5%) that percent mass ratio is 10% in step 5, the ceramic powder that obtains in step 4, utilize drying tower or tablets press to make the spherical and powder granule of good fluidity.
Step 6, employing pressing machine (manually or automatically filler) make the ceramic pressed compact of desired shape with the powder granule that step 5 obtains by two-sided compacting, its pressing pressure is 120MPa; Or adopt shot forming technique to obtain the ceramic pressed compact of desired shape.
Step 7, ceramic pressed compact is put into the high-temperature resistant aluminium oxide crucible of sealing, carry out stoking, form ceramic blank.Wherein, most high sintering temperature is 1350 degrees Celsius, and soaking time is 3 hours.
The ceramic blank that step 8, taking-up are burnt till, obtains the ceramics sample of desired size, to test after the surface treatment such as grinding, polishing.Then, utilize network analyzer to record its dielectric properties index to be respectively: ε
r=43.7; τ
f=21.5ppm/ DEG C; Q × f=41000 (test frequency is 1.1GHz).
Embodiment three
A preparation method for microwave dielectric ceramic materials, comprising:
Step one, before batching by former for Neodymium trioxide powder 800 degrees Celsius of lower pre-burnings 3 hours, carry out drying to get rid of moisture; According to chemical formula 0.62Ca
1+0.15mol%tiO
3-0.38NdAlO
3proportioning calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide, zirconium dioxide abrading-ball is added as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed in spherical tank and carry out mechanical uniform mixing, and after formation powder granule, removing organic solvent carries out drying treatment, and mixed powder, abrading-ball, solvent (weight) ratio is 1:3:3 and it accounts for 60% ~ 80% of spherical tank volume, and raw material mixing time is 2 hours.
In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.62mol%, and the stoichiometric ratio of aluminum oxide and Neodymium trioxide is 0.38mol%, and the stoichiometric ratio of calcium oxide is 0.15mol%, to increase the percentage composition of Ca element.It should be noted that, the purity of calcium carbonate, calcium oxide and alumina powder is all greater than 99.5%, and the purity of titanium dioxide and Neodymium trioxide powder is not less than 99.9%.
Step 2, with zirconium dioxide abrading-ball for grinding medium, carry out first time high-energy ball milling after powder granule drying step one formed, so that even for powder granule refinement is formed refinement powder.Wherein, High Energy Ball Milling Time is 3 hours, and ratio of grinding media to material is 12:1, and rotating speed is 800 revs/min.
Step 3, by step 2 formed refinement powder be placed in airtight high-temperature crucible, there is through high-temperature calcination Reactive Synthesis the presoma powder of high purity principal crystalline phase.Wherein, calcining temperature is 900 degrees Celsius, and soaking time is 5 hours.
Step 4, with zirconium dioxide abrading-ball for grinding medium, presoma powder after calcining is carried out the ceramic powder that second time high-energy ball milling obtains further evenly refinement.Wherein, High Energy Ball Milling Time is 2 hours, and ratio of grinding media to material is 10:1, and rotating speed is 800 revs/min.
Add polyvinyl alcohol (PVA) aqueous solution (concentration is 5%) that percent mass ratio is 10% in step 5, the ceramic powder that obtains in step 4, utilize spray-drying tower or tablets press to make the spherical and powder granule of good fluidity.
Step 6, employing pressing machine (manually or automatically filler) make the ceramic pressed compact of desired shape with the powder granule that step 5 obtains by two-sided compacting, its pressing pressure is 120MPa; Or adopt shot forming technique to obtain the ceramic pressed compact of desired shape.
Step 7, ceramic pressed compact is put into the high-temperature resistant aluminium oxide crucible of sealing, carry out stoking, form ceramic blank.Wherein, most high sintering temperature is 1450 degrees Celsius, and soaking time is 4 hours.
The ceramic blank that step 8, taking-up are burnt till, obtains the ceramics sample of desired size, to test after the surface treatment such as grinding, polishing.Then, utilize network analyzer to record its dielectric properties index to be respectively: ε
r=45.2; τ
f=5.6ppm/ DEG C; Q × f=48400 (test frequency is 1.1GHz).
Embodiment four
A preparation method for microwave dielectric ceramic materials, comprising:
Step one, before batching by former for Neodymium trioxide powder 800 degrees Celsius of lower pre-burnings 3 hours, to carry out drying; According to chemical formula 0.52Ca
1+0.25mol%tiO
3-0.48NdAlO
3proportioning calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide, zirconium dioxide abrading-ball is added as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed in spherical tank and carry out mechanical uniform mixing, and after formation powder granule, removing organic solvent carries out drying treatment, and mixed powder, abrading-ball, solvent (weight) ratio is 1:3:3 and it accounts for 60% ~ 80% of spherical tank volume, and raw material mixing time is 3 hours.
In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.52mol%, and the stoichiometric ratio of aluminum oxide and Neodymium trioxide is 0.48mol%, and the stoichiometric ratio of calcium carbonate is 0.25mol%, to increase the percentage composition of Ca element.It should be noted that, the purity of calcium carbonate, calcium oxide and alumina powder is all greater than 99.5%, and the purity of titanium dioxide and Neodymium trioxide powder is not less than 99.9%.
Step 2, with zirconium dioxide abrading-ball for grinding medium, carry out first time high-energy ball milling after powder granule drying step one formed, so that even for powder granule refinement is formed refinement powder.Wherein, High Energy Ball Milling Time is 3 hours, and ratio of grinding media to material is 10:1, and rotating speed is 600 revs/min.
Step 3, by step 2 formed refinement powder be placed in airtight high-temperature crucible, there is through high-temperature calcination Reactive Synthesis the presoma powder of high purity principal crystalline phase.Wherein, calcining temperature is 1150 degrees Celsius, and soaking time is 4 hours.
Step 4, with zirconium dioxide abrading-ball for grinding medium, presoma powder after calcining is carried out the ceramic powder that second time high-energy ball milling obtains further evenly refinement.Wherein, High Energy Ball Milling Time is 2 hours, and ratio of grinding media to material is 8:1, and rotating speed is 1000 revs/min.
Add polyvinyl alcohol (PVA) aqueous solution (concentration is 5%) that percent mass ratio is 10% in step 5, the ceramic powder that obtains in step 4, utilize spray-drying tower or tablets press to make the spherical and powder granule of good fluidity.
Step 6, employing pressing machine (manually or automatically filler) make the ceramic pressed compact of desired shape with the powder granule that step 5 obtains by two-sided compacting, its pressing pressure is 120MPa; Or adopt shot forming technique to obtain the ceramic pressed compact of desired shape.
Step 7, ceramic pressed compact is put into the high-temperature resistant aluminium oxide crucible of sealing, carry out stoking, form ceramic blank.Wherein, most high sintering temperature is 1250 degrees Celsius, and soaking time is 6 hours.
The ceramic blank that step 8, taking-up are burnt till, obtains the ceramics sample of desired size, to test after the surface treatment such as grinding, polishing.Then, utilize network analyzer to record its dielectric properties index to be respectively: ε
r=44.7; τ
f=-8.4ppm/ DEG C; Q × f=42600 (test frequency is 1.1GHz).
Embodiment five
The processing parameter identical with the preparation method of the microwave dielectric ceramic materials of embodiment three is adopted to carry out manufacturing experimently to the sample increasing Ca element percentage composition (y) in right amount and detect, thus the above embodiment of the present invention is applied in specific environment is described in detail, the fundamental property index of gained sample refers to table 1-2.
The different molar percentage calcium carbonate of table 1 (CaCO
3) the dielectric properties index of corresponding sample
The dielectric properties index of table 2 different molar percentage calcium oxide (CaO) corresponding sample
Embodiment six
With the dielectric sample preparation technology of embodiment three, appropriate interpolation property-modifying additive and sintering aid, property-modifying additive is CaO, SrO, TiO
2, ZnO, Al
2o
3, Nb
2o
5and Ta
2o
5in one or more, sintering aid is Bi
2o
3, B
2o
3, CuO, V
2o
5and one or more in BaO, the formula of this microwave dielectric ceramic materials is according to chemical formula 0.62Ca
(1+0.15mol%)tiO
3-0.38NdAlO
3) carry out proportioning.Wherein, the mass percent of property-modifying additive is 1% ~ 4% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount, the mass percent of sintering aid is 0.1% ~ 1% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount, and adopt same process parameter to carry out trial-manufacture of sample and detection, thus the above embodiment of the present invention is applied in specific environment is described in detail, its fundamental property index refers to table 3-4.
The dielectric properties index of the corresponding sample of table 3 different ratio property-modifying additive
The dielectric properties index of the corresponding sample of table 4 different ratio sintering aid
The embodiment of the present invention on the basis of traditional mechanically mixing and solid phase reaction method in conjunction with high-energy ball-milling process, the even refinement of ceramic powder is impelled by first time high-energy ball milling, not only effectively reduce powder calcined temperature, and ensure that the ceramic powder principal crystalline phase of Reactive Synthesis has high purity.Powder granule evenly refinement is further impelled by second time high-energy ball milling, for mist projection granulating establishes good granularity basis, and reduce sintering temperature, and increase the molar percentage of Volatile Elements Ca in the feed, inhibit volatile " the lattice imperfection effect " caused of Ca element in sintering process, ensure that the high compaction of Low fire ceramic.
Refer to Fig. 2, Figure 2 shows that in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, use conventional solid reaction synthesis process in conjunction with high-energy ball-milling process through the first time particle size distribution figure (a) of refinement powder that obtains of high-energy ball milling and use conventional solid reaction synthesis process in conjunction with high-energy ball-milling process and X-ray diffraction (XRD) collection of illustrative plates (b) of microwave-medium ceramics sample that obtains of the preparation method increasing Ca element percentage composition.
The X-coordinate of particle size distribution figure (a) is particle size diameter, unit is μm, ordinate zou is powder volume, unit is %, can find out after adopting the preparation method of microwave dielectric ceramic materials of the present invention to carry out first time high-energy ball milling from particle size distribution figure (a), refinement powder particles high concentration, granularity narrows obviously, and diameter is generally less than 1 μm.The X-coordinate of X-ray diffraction (XRD) collection of illustrative plates (b) is 2 θ angles, unit is degree, ordinate zou is the counting that receptor detects, unit is CPS, from X-ray diffraction (XRD) collection of illustrative plates (b), do not find any assorted peak, therefore its crystalline structure (principal crystalline phase) is single-phase orthogonal type perovskite structure.
Refer to Fig. 3, Figure 3 shows that in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, the microwave-medium ceramics sample using conventional solid reaction synthesis process to obtain in conjunction with the preparation method of high-energy ball-milling process and use conventional solid reaction synthesis process in conjunction with high-energy ball-milling process and scanning electron microscope (SEM) contrast images (a) of the microwave-medium ceramics sample obtained by the appropriate preparation method increasing Ca element percentage composition and (b).
Microwave dielectric ceramic materials not only unobvious local hole (pore) adopting the preparation method of microwave dielectric ceramic materials of the present invention to obtain obviously can be found out from figure, and porcelain body size distribution is more even, fine and close, effectively inhibit " lattice imperfection effect ".
By the way, the preparation method of microwave dielectric ceramic materials of the present invention is by increasing Volatile Elements Ca Mole percent when twice high-energy ball milling in the feed, " the lattice imperfection effect " that Volatile Elements Ca can be suppressed to produce, reduce sintering temperature to a great extent and shorten sintering time, and realize high compaction, reduce production cost and technical difficulty.
Claims (4)
1. a preparation method for microwave dielectric ceramic materials, is characterized in that, comprising:
The mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide is carried out mechanical uniform mixing, and form powder granule, the formula of described mixed powder is according to chemical formula (1-x) Ca
1+ytiO
3-x [NdAlO
3] make wherein x and y meet 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% respectively; The purity of described calcium carbonate, calcium oxide and aluminum oxide is all greater than 99.5%, and the purity of described titanium dioxide and Neodymium trioxide is not less than 99.9%;
Described powder granule is carried out first time high-energy ball milling, and with by even for described powder granule refinement, form refinement powder, wherein, ratio of grinding media to material is 8:1 ~ 10:1, and Ball-milling Time is 1 ~ 3 hour, and rotating speed is 600 ~ 800 revs/min;
Described refinement powder is carried out high-temperature calcination in encloses container, and form presoma powder, wherein, calcining temperature is 900 ~ 1200 degrees Celsius, and soaking time is 3 ~ 6 hours;
Described presoma powder is carried out second time high-energy ball milling, wherein, ratio of grinding media to material is 10:1 ~ 12:1, Ball-milling Time 1 ~ 3 hour, rotating speed 600 ~ 1000 revs/min, and add property-modifying additive and sintering aid, with by the further evenly refinement of described presoma powder, form ceramic powder, wherein, refinement powder granularity after described first time high-energy ball milling is distributed within the scope of 1 ~ 2 μm, and the granularity of the ceramic powder after described second time high-energy ball milling is less than 1 μm, and described property-modifying additive is CaO, SrO, ZnO, Al
2o
3, Nb
2o
5and TiO
2in one or more, described sintering aid is Bi
2o
3, B
2o
3, CuO, V
2o
5and one or more in BaO;
Mist projection granulating, adds in described ceramic powder that concentration is 5%, mass percent is the polyvinyl alcohol water solution of 5% ~ 10%, described ceramic powder is made the powder granule of the spherical mobility of tool;
Compression moulding, makes the ceramic pressed compact of desired shape by the powder granule of spherical for described tool mobility;
Sintering, carries out stoking by described ceramic pressed compact, forms ceramic blank, and wherein, most high sintering temperature is 1200 ~ 1500 degrees Celsius, and soaking time is 3 ~ 6 hours;
Mechanical workout and sample detection, carry out surface treatment by described ceramic blank and obtain ceramics sample, and measure the dielectric properties index of described ceramics sample;
Described the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide is carried out mechanical uniform mixing, the step forming powder granule comprises:
Described mixed powder is placed in spherical tank, add zirconium dioxide abrading-ball as grinding medium, add dehydrated alcohol and carry out mechanical uniform mixing as organic solvent, and after the described powder granule of formation, removing organic solvent carries out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight are 1:3:3 and account for 60% ~ 80% of spherical tank volume, and mixing time is 1 ~ 3 hour.
2. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, described ceramic pressed compact carries out two-sided compression moulding by pressing machine in filler mode manually or automatically.
3. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, in described high-temperature calcinations step, encloses container is high-temperature crucible.
4. the preparation method of microwave dielectric ceramic materials according to claim 1, it is characterized in that, the mass percent of described property-modifying additive is 1% ~ 4% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount, and the mass percent of described sintering aid is 0.1% ~ 1% of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide total amount.
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| JP2001199763A (en) * | 1999-11-12 | 2001-07-24 | Ube Ind Ltd | Dielectric porcelain composition |
| KR20020029446A (en) * | 2000-09-15 | 2002-04-19 | 박호군 | Process for Preparing Ultrafine Barium Titanate Dielectric Ceramic Material |
| JP2008143769A (en) * | 2006-12-07 | 2008-06-26 | Korea Inst Of Machinery & Materials | Nano-size lead-free piezoceramic powder and method of synthesizing the same |
| CN101555135A (en) * | 2009-05-05 | 2009-10-14 | 张家港保税区灿勤科技有限公司 | Microwave medium ceramic material with ultrahigh Q-value middle dielectric constant |
| CN101891475A (en) * | 2010-07-08 | 2010-11-24 | 桂林理工大学 | Preparation method of potassium-sodium niobate-potassium-bismuth titanate nano ceramics |
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|---|---|---|---|---|
| JP2001199763A (en) * | 1999-11-12 | 2001-07-24 | Ube Ind Ltd | Dielectric porcelain composition |
| KR20020029446A (en) * | 2000-09-15 | 2002-04-19 | 박호군 | Process for Preparing Ultrafine Barium Titanate Dielectric Ceramic Material |
| JP2008143769A (en) * | 2006-12-07 | 2008-06-26 | Korea Inst Of Machinery & Materials | Nano-size lead-free piezoceramic powder and method of synthesizing the same |
| CN101555135A (en) * | 2009-05-05 | 2009-10-14 | 张家港保税区灿勤科技有限公司 | Microwave medium ceramic material with ultrahigh Q-value middle dielectric constant |
| CN101891475A (en) * | 2010-07-08 | 2010-11-24 | 桂林理工大学 | Preparation method of potassium-sodium niobate-potassium-bismuth titanate nano ceramics |
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