CN103172366A - Preparation method of microwave dielectric ceramic material - Google Patents
Preparation method of microwave dielectric ceramic material Download PDFInfo
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- CN103172366A CN103172366A CN2011104356100A CN201110435610A CN103172366A CN 103172366 A CN103172366 A CN 103172366A CN 2011104356100 A CN2011104356100 A CN 2011104356100A CN 201110435610 A CN201110435610 A CN 201110435610A CN 103172366 A CN103172366 A CN 103172366A
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Abstract
The invention discloses a preparation method of a microwave dielectric ceramic material. The preparation method comprises the following steps of: mechanically mixing mixed powder of calcium carbonate, calcium oxide, alumina, neodymia and titanium dioxide uniformly to form powder particles; carrying out primary high-energy ball milling on the powder particles to uniformly refine the powder particles to form refined powder; calcining the refined powder at a high temperature in a closed container to form precursor powder; and carrying out secondary high-energy ball milling on the precursor powder to further refine the precursor powder uniformly to form ceramic powder. The preparation method has the beneficial effects that the lattice defect effects caused by the volatile element Ca can be inhibited by appropriately increasing the mole percent of the volatile element Ca in the raw materials and combining with the two-time high-energy ball milling processes, thus greatly reducing the sintering temperature and shortening the sintering time, achieving high densification and reducing the production cost and the technical difficulty.
Description
Technical field
The present invention relates to the stupalith field, particularly relate to a kind of preparation method of microwave dielectric ceramic materials.
Background technology
Microwave-medium ceramics is to be applicable to the medium dielectric constant microwave medium of microwave frequency band and the stupalith of high quality factor, bringing into play the functions such as media isolated, Medium Wave Guide and dielectric resonance in microwave circuit, can be used for making the microwave hybrid integrated circuit take microwave tube, pipe racks line etc. as main composition, reduced largely quality and the volume of the devices such as microwave dielectric resonator.
Wherein, (1-x) CaTiO that has 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
f～0) and quite high quality factor (Q * f＞30000), thus caused extensive concern and the research of industry.Yet the research of industry mainly rests on the mutual relationship of dielectric properties of the microtexture of its material and dielectric properties and firing process and material, for the research of its preparation method seldom.
In present prior art, the preparation method that domestic and international manufacturer mostly adopts mechanically mixing to be combined with solid state sintering, solid state reaction occurs under the high-temperature calcination condition and prepare required ceramic powder after being about to the solid powder raw material and fully mixing in planetary or stirring ball mill, and then compression moulding, solid state sintering become medium ceramic material.This traditional preparation method mainly contains following defective: in high-temperature sintering process, the powder reactive behavior is relatively poor, needs very high sintering temperature (more than at least 1450 degrees centigrade) and long sintering time, causes the high production energy consumption of needs; The synthetic ceramic powder particle diameter of reaction is larger, 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, namely is difficult to obtain to possess the medium ceramic material of stablizing good microwave dielectric property; Ignored the detrimentally affect that Ca element volatile " lattice imperfection effect " in sintering process causes the microwave property of product.
Therefore, need to provide a kind of preparation method of microwave dielectric ceramic materials, to solve the problem that in prior art, in preparation microwave dielectric ceramic materials process, sintering temperature is too high, sintering time is long and be difficult to realize sintering densification.
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 reduce sintering temperature, shorten sintering time and suppress " the lattice imperfection effect " that Volatile Elements Ca causes in preparation microwave dielectric ceramic materials process.
For solving the problems of the technologies described above, the invention provides 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 the mechanical uniform mixing, form powder granule; Powder granule is carried out high-energy ball milling for the first time, with the even refinement of powder granule, form the refinement powder; The refinement powder is carried out high-temperature calcination in encloses container, form the presoma powder; The presoma powder is carried out high-energy ball milling for the second time, with the further evenly refinement of presoma powder, form ceramic powder.
Wherein, also comprise after the high-energy ball milling step for the second time: mist projection granulating, add concentration and be 5%, mass percent is 5%～10% polyvinyl alcohol water solution, ceramic powder is made the powder granule of the spherical mobility of tool in ceramic powder.
Wherein, also comprise after the mist projection granulating step: compression moulding, the powder granule of the spherical mobility of tool is made the ceramic pressed compact of desired shape.
Wherein, ceramic pressed compact is to carry out two-sided compression moulding by pressing machine in filler mode manually or automatically, perhaps carries out shot moulding by shot forming technique.
Wherein, also comprise after the compression moulding step: sintering, ceramic pressed compact is carried out stoking, form ceramic blank, wherein, the highest sintering temperature is 1200～1500 degrees centigrade, soaking time is 3～6 hours.
Wherein, also comprise after sintering step: mechanical workout and sample detection, ceramic blank is carried out surface treatment obtain ceramics sample, and measure the dielectric properties index of ceramics sample.
Wherein, the formula of mixed powder is according to chemical formula (1-x) Ca
1+yTiO
3-x[NdAlO
3] make wherein that x and y satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).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%.
wherein, with calcium carbonate, calcium oxide, aluminum oxide, the mixed powder of Neodymium trioxide and titanium dioxide carries out mechanical uniform to be mixed, the step that forms powder granule comprises: mixed powder is placed in spherical tank, add the zirconium dioxide abrading-ball as grinding medium, adding dehydrated alcohol or deionized water to carry out mechanical uniform as organic solvent mixes, and after forming powder granule, remove organic solvent and carry out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight is 1: 3: 3 and accounts for 60%～80% of spherical tank volume, mixing time is 1～3 hour.
Wherein, in high-energy ball milling step for the first time, 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 rev/mins.
Wherein, the refinement powder granularity after high-energy ball milling is distributed in 1～2 μ m scope for the first time.
Wherein, in the high-temperature calcination step, encloses container is high-temperature crucible, and calcining temperature is 900～1200 degrees centigrade, and soaking time is 3～6 hours.
Wherein, in high-energy ball milling step for the second time, ratio of grinding media to material is 10: 1～12: 1, Ball-milling Time 1～3 hour, 600～1000 rev/mins of rotating speeds.
Wherein, for the second time the granularity of the ceramic powder after high-energy ball milling less than 1 μ m.
Wherein, in high-energy ball milling step for the second time, further add property-modifying additive and sintering aid.
Wherein, 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.
Wherein, the formula of microwave dielectric ceramic materials is according to chemical formula (1-x) Ca
1+yTiO
3-x[NdAlO
3] make x and y satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).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 that is different from prior art, the preparation method of microwave dielectric ceramic materials of the present invention is by increasing Volatile Elements Ca molar percentage and twice high-energy ball milling in raw material, " the lattice imperfection effect " that can suppress the volatile generation of Ca element, reduce to a great extent sintering temperature and shorten sintering time, and realize high compaction, reduce production costs and technical difficulty.
Description of drawings
In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, during the below will describe embodiment, the accompanying drawing of required use is done to introduce simply, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings, wherein:
Fig. 1 is preparation method's the schematic flow sheet 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 the particle size distribution figure (a) of the refinement powder that traditional solid state reaction synthetic method makes through high-energy ball milling for the first time in conjunction with high-energy ball-milling process and uses traditional solid state reaction synthetic method in conjunction with high-energy ball-milling process and increase X-ray diffraction (XRD) collection of illustrative plates (b) of the microwave-medium ceramics sample that the preparation method of Ca element percentage composition makes;
Fig. 3 is in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, uses the microwave-medium ceramics sample that traditional solid state reaction synthetic method makes in conjunction with the preparation method of high-energy ball-milling process and uses scanning electron microscope (SEM) contrast images (a) of the microwave-medium ceramics sample that traditional solid state reaction synthetic method makes in conjunction with high-energy ball-milling process and the preparation method by appropriate increase Ca element percentage composition and (b).
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment in the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.
Embodiment one
A kind of preparation method of microwave dielectric ceramic materials, its schematic flow sheet comprises as shown in Figure 1:
Step S101 carries out mechanical uniform with the mixed powder of calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide and mixes, and forms powder granule.
Step S101 comprises mixed powder is placed in spherical tank, add the zirconium dioxide abrading-ball as grinding medium, adding dehydrated alcohol or deionized water to carry out mechanical uniform as organic solvent mixes, and after forming powder granule, remove organic solvent and carry out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight be 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 satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).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, improved the molar percentage of Volatile Elements Ca in the CTNA based dielectric material, can suppress " lattice imperfection effect " that Volatile Elements Ca causes.
Step S102 carries out high-energy ball milling for the first time with powder granule, with the even refinement of powder granule, forms the refinement powder.
In the present embodiment, carry out high-energy ball milling for the first time with the zirconium dioxide abrading-ball as the grinding medium of high-energy ball milling, make the size-grade distribution of the refinement powder after high-energy ball milling for the first time in 1～2 μ m scope, reactive behavior and the contact area of powder granule have effectively been improved, and then reach the purpose that reduces the 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 rev/mins.
Step S103 carries out the refinement powder high-temperature calcination in encloses container, form the presoma powder.
In the present embodiment, the powder after high-energy ball milling for the first time 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 calcination process is: encloses container is high-temperature crucible, and calcining temperature is 900～1200 degrees centigrade, and soaking time is 3～6 hours.
Step S104 carries out high-energy ball milling for the second time with the presoma powder, with the further evenly refinement of presoma powder, forms ceramic powder.
In the present embodiment, with the grinding medium of zirconium dioxide abrading-ball as high-energy ball milling, and further add property-modifying additive and sintering aid carries out high-energy ball milling for the second time.Control the granularity of the ceramic powder that forms less than 1 μ m, 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 satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).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, 600～1000 rev/mins of rotating speeds.
By adding property-modifying additive and sintering aid, ceramic powder is further evenly distributed, reduce the porosity between ceramic powder, can reach the purpose that reduces to a certain extent sintering temperature and microwave-medium ceramics sintering densification.
In addition, in the present embodiment, after ceramic powder is formed, can also be further comprising the steps as required:
Mist projection granulating adds concentration and is 5%, mass percent is 5%～10% polyvinyl alcohol water solution, ceramic powder is made the powder granule of the spherical mobility of tool, so that this powder granule has good mobility in ceramic powder.
The ceramic pressed compact of desired shape is made the powder granule of the spherical mobility of tool in compression moulding.
In the present embodiment, ceramic pressed compact is to carry out two-sided compression moulding by pressing machine in filler mode manually or automatically, perhaps carries out shot moulding by shot forming technique.Wherein, pressing pressure is 80～120MPa.
Sintering carries out stoking with ceramic pressed compact, forms ceramic blank, and wherein, the highest sintering temperature is 1200～1500 degrees centigrade, and soaking time is 3～6 hours.
In the present embodiment, ceramic pressed compact is put into airtight high-temperature resistant aluminium oxide crucible carry out stoking, in the high temperature period, solid state reaction occurs and generate fine and close ceramic blank.
Mechanical workout and sample detection are carried out surface treatment with ceramic blank and are obtained ceramics sample, and measure the dielectric properties index of ceramics sample.
In the present embodiment, can adopt the mechanical workout modes such as grinding, polishing 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 kind of preparation method of microwave dielectric ceramic materials comprises:
Step 1, before batching with the former powder of Neodymium trioxide 800 degrees centigrade 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, add the zirconium dioxide abrading-ball as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed on and carry out the mechanical uniform mixing in spherical tank, and after forming powder granule, remove organic solvent and carry out drying treatment, mixed powder, abrading-ball, solvent (weight) ratio are that 1: 3: 3 and its account for 60%～80% of spherical tank volume, and the 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.Need to prove, 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 3, the refinement powder that step 2 is formed are placed in airtight high-temperature crucible, through the synthetic presoma powder with high purity principal crystalline phase of high-temperature calcination reaction.Wherein, calcining temperature is 1000 degrees centigrade, and soaking time is 3 hours.
Step 4, take the zirconium dioxide abrading-ball as grinding medium, presoma powder after calcining is carried out high-energy ball milling for the second time obtains further the evenly ceramic powder of 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 rev/mins.
Step 5, the mass percent example of adding in the ceramic powder that step 4 obtains are 10% polyvinyl alcohol (PVA) aqueous solution (concentration is 5%), utilize drying tower or tablets press to make the powder granule of spherical and good fluidity.
Step 6, the powder granule that adopts pressing machine (filler manually or automatically) with two-sided compacting, step 5 to be obtained are made the ceramic pressed compact of desired shape, and its pressing pressure is 120MPa; Perhaps 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, carried out stoking, form ceramic blank.Wherein, the highest sintering temperature is 1350 degrees centigrade, and soaking time is 3 hours.
The ceramic blank that step 8, taking-up are burnt till obtains the ceramics sample of desired size, in order to test after the surface treatments such as grinding, polishing.Then, utilizing network analyzer to record its dielectric properties index is respectively: ε
r=43.7; τ
f=21.5ppm/ ℃; Q * f=41000 (test frequency is 1.1GHz).
Embodiment three
A kind of preparation method of microwave dielectric ceramic materials comprises:
Step 1, before batching with the former powder of Neodymium trioxide 800 degrees centigrade 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, add the zirconium dioxide abrading-ball as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed on and carry out the mechanical uniform mixing in spherical tank, and after forming powder granule, remove organic solvent and carry out drying treatment, mixed powder, abrading-ball, solvent (weight) ratio are that 1: 3: 3 and its account for 60%～80% of spherical tank volume, and the 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.Need to prove, 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 3, the refinement powder that step 2 is formed are placed in airtight high-temperature crucible, through the synthetic presoma powder with high purity principal crystalline phase of high-temperature calcination reaction.Wherein, calcining temperature is 900 degrees centigrade, and soaking time is 5 hours.
Step 4, take the zirconium dioxide abrading-ball as grinding medium, presoma powder after calcining is carried out high-energy ball milling for the second time obtains further the evenly ceramic powder of 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 rev/mins.
Step 5, the mass percent example of adding in the ceramic powder that step 4 obtains are 10% polyvinyl alcohol (PVA) aqueous solution (concentration is 5%), utilize spray-drying tower or tablets press to make the powder granule of spherical and good fluidity.
Step 6, the powder granule that adopts pressing machine (filler manually or automatically) with two-sided compacting, step 5 to be obtained are made the ceramic pressed compact of desired shape, and its pressing pressure is 120MPa; Perhaps 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, carried out stoking, form ceramic blank.Wherein, the highest sintering temperature is 1450 degrees centigrade, and soaking time is 4 hours.
The ceramic blank that step 8, taking-up are burnt till obtains the ceramics sample of desired size, in order to test after the surface treatments such as grinding, polishing.Then, utilizing network analyzer to record its dielectric properties index is respectively: ε
r=45.2; τ
f=5.6ppm/ ℃; Q * f=48400 (test frequency is 1.1GHz).
Embodiment four
A kind of preparation method of microwave dielectric ceramic materials comprises:
Step 1, before batching with the former powder of Neodymium trioxide 800 degrees centigrade 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, add the zirconium dioxide abrading-ball as grinding medium in mixed powder, add dehydrated alcohol or deionized water as organic solvent, be placed on and carry out the mechanical uniform mixing in spherical tank, and after forming powder granule, remove organic solvent and carry out drying treatment, mixed powder, abrading-ball, solvent (weight) ratio are that 1: 3: 3 and its account for 60%～80% of spherical tank volume, and the 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.Need to prove, 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 3, the refinement powder that step 2 is formed are placed in airtight high-temperature crucible, through the synthetic presoma powder with high purity principal crystalline phase of high-temperature calcination reaction.Wherein, calcining temperature is 1150 degrees centigrade, and soaking time is 4 hours.
Step 4, take the zirconium dioxide abrading-ball as grinding medium, presoma powder after calcining is carried out high-energy ball milling for the second time obtains further the evenly ceramic powder of 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 rev/mins.
Step 5, the mass percent example of adding in the ceramic powder that step 4 obtains are 10% polyvinyl alcohol (PVA) aqueous solution (concentration is 5%), utilize spray-drying tower or tablets press to make the powder granule of spherical and good fluidity.
Step 6, the powder granule that adopts pressing machine (filler manually or automatically) with two-sided compacting, step 5 to be obtained are made the ceramic pressed compact of desired shape, and its pressing pressure is 120MPa; Perhaps 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, carried out stoking, form ceramic blank.Wherein, the highest sintering temperature is 1250 degrees centigrade, and soaking time is 6 hours.
The ceramic blank that step 8, taking-up are burnt till obtains the ceramics sample of desired size, in order to test after the surface treatments such as grinding, polishing.Then, utilizing network analyzer to record its dielectric properties index is respectively: ε
r=44.7; τ
f=-8.4ppm/ ℃; Q * f=42600 (test frequency is 1.1GHz).
Embodiment five
The employing processing parameter identical with the preparation method of the microwave dielectric ceramic materials of embodiment three manufactured experimently and detected the sample of appropriate increase Ca element percentage composition (y), be described in detail thereby the above embodiment of the present invention is applied in specific environment, the fundamental property index of gained sample sees table 1-2 for details.
The different molar percentage calcium carbonate of table 1 (CaCO
3) the dielectric properties index of corresponding sample
The dielectric properties index of the corresponding sample of the different molar percentage calcium oxide of table 2 (CaO)
Embodiment six
With the dielectric sample preparation technology of embodiment three, add in right amount 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 the same process parameter to carry out trial-manufacture of sample and detection, be described in detail thereby the above embodiment of the present invention is applied in specific environment, its fundamental property index sees table 3-4 for details.
The dielectric properties index of the corresponding sample of the different proportioning property-modifying additives of table 3
The dielectric properties index of the corresponding sample of the different proportioning sintering aids of table 4
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, impel the even refinement of ceramic powder by high-energy ball milling for the first time, not only effectively reduce the powder calcined temperature, and guaranteed that the synthetic ceramic powder principal crystalline phase of reaction has high purity.Impel further evenly refinement of powder granule by high-energy ball milling for the second time, for mist projection granulating is established good granularity basis, and reduced sintering temperature, and increase the molar percentage of Volatile Elements Ca in raw material, suppress volatile " the lattice imperfection effect " that causes of Ca element in the sintering process, guaranteed the high compaction of Low fire ceramic.
See also Fig. 2, Figure 2 shows that in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, use the particle size distribution figure (a) of the refinement powder that traditional solid state reaction synthetic method makes through high-energy ball milling for the first time in conjunction with high-energy ball-milling process and use traditional solid state reaction synthetic method in conjunction with high-energy ball-milling process and increase X-ray diffraction (XRD) collection of illustrative plates (b) of the microwave-medium ceramics sample that the preparation method of Ca element percentage composition makes.
The X-coordinate of particle size distribution figure (a) is particle size diameter, unit is μ m, ordinate zou is the powder volume, unit is %, after can finding out that from particle size distribution figure (a) preparation method who adopts microwave dielectric ceramic materials of the present invention carries out for the first time high-energy ball milling, refinement powder particles high concentration, granularity narrow obviously, and diameter is generally less than 1 μ m.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, do not find any assorted peak from X-ray diffraction (XRD) collection of illustrative plates (b), so its crystalline structure (principal crystalline phase) is single-phase orthogonal type perovskite structure.
See also Fig. 3, Figure 3 shows that in the preparation method of microwave dielectric ceramic materials according to an embodiment of the invention, use the microwave-medium ceramics sample that traditional solid state reaction synthetic method makes in conjunction with the preparation method of high-energy ball-milling process and use scanning electron microscope (SEM) contrast images (a) of the microwave-medium ceramics sample that traditional solid state reaction synthetic method makes in conjunction with high-energy ball-milling process and the preparation method by appropriate increase Ca element percentage composition and (b).
Can find out obviously that from figure the microwave dielectric ceramic materials that the preparation method that adopts microwave dielectric ceramic materials of the present invention makes does not only have obvious local hole (pore), and the porcelain body size distribution is more even, fine and close, has effectively suppressed " lattice imperfection effect ".
By the way, the preparation method of microwave dielectric ceramic materials of the present invention is by increasing Volatile Elements Ca molar percentage and twice high-energy ball milling in raw material, can suppress " lattice imperfection effect " that Volatile Elements Ca produces, reduce to a great extent sintering temperature and shorten sintering time, and realize high compaction, reduce production costs and technical difficulty.
The above is only embodiments of the invention; not thereby limit the scope of the claims of the present invention; every equivalent structure or equivalent flow process conversion that utilizes specification sheets of the present invention and accompanying drawing content to do; or directly or indirectly be used in other relevant technical fields, all in like manner be included in scope of patent protection of the present invention.
Claims (16)
1. the preparation method of a 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 the mechanical uniform mixing, form powder granule;
Described powder granule is carried out high-energy ball milling for the first time, with the even refinement of described powder granule, form the refinement powder;
Described refinement powder is carried out high-temperature calcination in encloses container, form the presoma powder;
Described presoma powder is carried out high-energy ball milling for the second time, with the further evenly refinement of described presoma powder, form ceramic powder.
2. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, also comprises after the described step of high-energy ball milling for the second time:
Mist projection granulating adds concentration and is 5%, mass percent is 5%～10% polyvinyl alcohol water solution, described ceramic powder is made the powder granule of the spherical mobility of tool in described ceramic powder.
3. the preparation method of microwave dielectric ceramic materials according to claim 2, is characterized in that, also comprises after described mist projection granulating step:
The ceramic pressed compact of desired shape is made the powder granule of the spherical mobility of described tool in compression moulding.
4. the preparation method of microwave dielectric ceramic materials according to claim 3, it is characterized in that, described ceramic pressed compact is to carry out two-sided compression moulding by pressing machine in filler mode manually or automatically, perhaps carries out shot moulding by shot forming technique.
5. the preparation method of microwave dielectric ceramic materials according to claim 3, is characterized in that, also comprises after described compression moulding step:
Sintering carries out stoking with described ceramic pressed compact, forms ceramic blank, and wherein, the highest sintering temperature is 1200～1500 degrees centigrade, and soaking time is 3～6 hours.
6. the preparation method of microwave dielectric ceramic materials according to claim 5, it is characterized in that, also comprise after described sintering: mechanical workout and sample detection, described ceramic blank is carried out surface treatment obtain ceramics sample, and measure the dielectric properties index of described ceramics sample.
7. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, the formula of described mixed powder is according to chemical formula (1-x) Ca
1+yTiO
3-x[NdAlO
3] make wherein that x and y satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).Wherein, 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%.
8. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, described mixed powder with calcium carbonate, calcium oxide, aluminum oxide, Neodymium trioxide and titanium dioxide carries out mechanical uniform to be mixed, and the step that forms powder granule comprises:
Described mixed powder is placed in spherical tank, add the zirconium dioxide abrading-ball as grinding medium, adding dehydrated alcohol or deionized water to carry out mechanical uniform as organic solvent mixes, and after forming described powder granule, remove organic solvent and carry out drying treatment, wherein, mixed powder, grinding medium, organic solvent three part by weight be 1: 3: 3 and account for 60%～80% of spherical tank volume, and mixing time is 1～3 hour.
9. the preparation method of microwave dielectric ceramic materials according to claim 1, is characterized in that, in the described step of high-energy ball milling for the first time, 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 rev/mins.
10. the preparation method of microwave dielectric ceramic materials according to claim 9, is characterized in that, the refinement powder granularity after described high-energy ball milling for the first time is distributed in 1～2 μ m scope.
11. the preparation method of microwave dielectric ceramic materials according to claim 1 is characterized in that, in described high-temperature calcination step, encloses container is high-temperature crucible, and calcining temperature is 900～1200 degrees centigrade, and soaking time is 3～6 hours.
12. the preparation method of microwave dielectric ceramic materials according to claim 1 is characterized in that, in the described step of high-energy ball milling for the second time, ratio of grinding media to material is 10: 1～12: 1, Ball-milling Time 1～3 hour, 600～1000 rev/mins of rotating speeds.
13. the preparation method of microwave dielectric ceramic materials according to claim 12 is characterized in that, the granularity of the ceramic powder after described high-energy ball milling for the second time is less than 1 μ m.
14. the preparation method of microwave dielectric ceramic materials according to claim 1 is characterized in that, in the described step of high-energy ball milling for the second time, further adds property-modifying additive and sintering aid.
15. the preparation method of microwave dielectric ceramic materials according to claim 14 is characterized in that, described property-modifying additive is CaO, SrO, TiO
2, ZnO, Al
2O
3, Nb
2O
5And Ta
2O
5In one or more, described sintering aid is Bi
2O
3, B
2O
3, CuO, V
2O
5And one or more in BaO.
16. the preparation method of microwave dielectric ceramic materials according to claim 15 is characterized in that, the formula of described medium ceramic material is according to chemical formula (1-x) Ca
1+yTiO
3-x[NdAlO
3] make x and y satisfy respectively 0.28mol%≤x≤0.48mol% and 0.05mol%≤y≤0.5mol% (the optional calcium carbonate of y or calcium oxide).Wherein, 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 |
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