Aluminium nitride ceramics material and preparation method thereof
Technical field
The present invention relates to a kind of aluminium nitride ceramics material and preparation method thereof, particularly a kind of aluminium nitride ceramics material that adds nano aluminium oxide and preparation method thereof.
Background technology
Along with electronic information, power electronics, semiconductor laser technique constantly develop to highly integrated, high-speedization, microminiaturization, intelligentized direction.Adapt with this trend, this has all proposed more, higher requirement to the ceramic substrate as one of main base components that plays load-carrying unit, interconnected, outer subsides, protection and refrigerative effect in circuit on quality and quantity.Especially thermal conductivity, the dielectric properties to baseplate material have all proposed more and more higher requiring a little.At present, the Al of widespread use
2O
3Ceramic substrate is the needs of the above-mentioned technical development of incompatibility more and more.Its major cause is Al
2O
3Thermal conductivity lower, be about 20-30W/mK, so heat dispersion does not far reach service requirements; And the BeO pottery with high heat conductance is just progressively eliminated owing to its high hypertoxicity.In order to improve high integrated IC, the heat dissipation characteristics of components and parts such as package casing and power model, new A lN pottery with high heat conductance, the about 160-230W/mK of the thermal conductivity of industrialization product, at the high power module circuit, silicon-controlled rectifier, high power transistor, semiconductor laser, high-power integrated circuit, solid-state relay, switch power supply and other require not only to insulate but also the high power device of high heat radiation on, and as the multi-functional portable phone microcircuit chip bearing substrate of G high frequency, the 4th generation field such as led light source circuit bearing substrate all shown huge superiority, use increasingly extensively, the market requirement is increasing.
With regard to the characteristic of AlN material itself, because AlN belongs to the covalent linkage compound, must be at N
2Sintering could obtain dense stupalith under 1850 ℃ the high temperature under the atmosphere protection, being higher than, and promptly is difficult to sintering; On the other hand because Al and O have very strong avidity, in case and O enter the AlN lattice and will cause oxygen defect to produce and the thermal conductivity that reduces the AlN pottery; In addition, often contain a spot of Al in the normally used AlN powder raw material
2O
3(≤1wt%).Therefore, in order to reduce sintering temperature, preparation high-compactness and to reduce AlN lattice oxygen defective, to obtain high heat conductance (〉 160W/mK) the AlN pottery, present existing technology be adopt add a small amount of (usually≤6wt%), as Y
2O
3, CaO, Li
2Oxide compounds such as O, or YF
3, CaF
2Deng the fluorochemical sintering aid,, obtain high thermal conductivity to realize densification sintering and to capture lattice oxygen.
All the time, for obtaining high thermal conductivity, people avoid as far as possible always or avoid and have aluminum oxide to exist in AlN, and purpose is in order to prevent that O from entering the AlN lattice, cause oxygen defect to produce and reduce the thermal conductivity of AlN pottery.Therefore, even a small amount of as Y by adding
2O
3, CaO, Li
2Oxide compounds such as O, or YF
3, CaF
2As sintering aid, the densification sintering temperature of AlN pottery is also mostly more than 1820 ℃, and is high in fluorochemical.Even if by further increasing the addition of sintering aid, perhaps adopt other sintering aid systems with lower solid melting temperatur, though can further reduce sintering temperature, the thermal conductivity that tends to cause reducing significantly aluminium nitride ceramics (usually<80W/mK).
With regard to the AlN ceramic product, except that some high radiator structure spare of increasingly extensive application, the product of consumption maximum is that employing has the flow casting molding technology of large scale continuous prod characteristics and the AlN ceramic substrate that technology is made (or claiming substrate) at present.Requirement for the development trend of the chip type that adapts to components and parts such as electronic information, power electronics, semiconductor laser technique, multilayer monolithization, miniaturization etc., and improve components and parts production efficiency of products and consistency of product, the substrate product towards smooth, bright and clean and thin (as≤0.2mm), (direction as 〉=6 * 6in) develops big area.Based on this outward appearance, the dimensional characteristic of substrate product, high sintering temperature be the more important thing is the performance that is not easy to control the substrate product except causing manufacturing cost increases, and as consistence, planeness and roughness of color and luster or the like, influences the qualification rate of product.
Summary of the invention
The purpose of this invention is to provide a kind of aluminium nitride ceramics material and preparation method thereof.
Aluminium nitride ceramics material provided by the invention is prepared by aluminium nitride, liquid phase sintering auxiliary agent, sintering aid and organic additive.
Wherein, aluminium nitride (AlN) can be for by carbothermic method, direct nitridation method or spread method synthetic powder certainly;
Sintering aid is Y
2O
3, CaO, Li
2O, YF
3And CaF
2In any one or any several mixtures with arbitrary proportion;
The liquid phase sintering auxiliary agent is nano aluminium oxide, aluminium secondary butylate (C
12H
27AlO
3), aluminum isopropylate (C
9H
21AlO
3) or aluminium acetylacetonate (C
15H
21AlO
6).
The method for preparing aluminium nitride ceramics material provided by the invention is to add nano aluminium oxide in existing commonly used preparation method's raw material, is prepared according to the preparation technology of ordinary method, to realize the liquid phase sintering of AlN pottery.This method is not only applicable to conventional dry-pressing formed, is applicable to large-scale industrialization quantity-produced flow casting molding method yet; Both can adopt normal pressure-sinteredly, and also can adopt hot-pressing sintering technique to prepare the AlN pottery.
The present invention adopts two kinds of technology approach to add nanometer Al to be implemented in the AlN pottery compositing formula
2O
3: one is that directly interpolation is nano alumina powder jointed, and its particle size can be regulated at 20-600nm; Two for adding organoaluminum, as aluminium secondary butylate (C
12H
27AlO
3), aluminum isopropylate (C
9H
21AlO
3) or aluminium acetylacetonate (C
15H
21AlO
6) the mixture of any one or its arbitrary proportion.Low-temperature decomposition by organoaluminum can obtain nano aluminium oxide indirectly, thereby is implemented in the purpose of adding nano aluminium oxide in existing preparation method's the raw material.
During this stupalith was raw materials used, the mass percent of aluminium nitride, liquid phase sintering auxiliary agent (by aluminum oxide) and sintering aid was 94-98:0-1:1-6; Wherein, the quality percentage composition of liquid phase sintering auxiliary agent is 0-1%, but does not comprise 0; The quality percentage composition of sintering aid is 1-6%, but does not comprise 6; The mole dosage of used organoaluminum is 2 times of mole dosage of nano aluminium oxide.
The used organic additive of moulding process comprises solvent, dispersion agent, binding agent and softening agent four classes.According to all kinds of mixtures by a certain percentage of process choice that adopt usually, wherein every kind can be selected a kind of or be several with arbitrary proportion blended mixture arbitrarily.Solvent, dispersion agent, binding agent and softening agent commonly used all is applicable to present method in the existing method.Wherein, solvent is preferably butanone and/or dehydrated alcohol; Binding agent is preferably polyvinyl butyral acetal (PVB); Softening agent is preferably dibutyl phthalate (DBP) (DBP) or polyoxyethylene glycol (PEG); Dispersion agent be preferably in fish oil, Viscotrol C or the triglyceride (GTO) any one or arbitrarily several with arbitrary proportion blended mixture, most preferably Viscotrol C.
Wherein, comprise the steps: with dry-pressing formed preparation AlN method of ceramic material
(1) mixing of materials, granulation: with ceramic raw material, comprise AlN powder, sintering aid, liquid phase sintering auxiliary agent, with organic additives such as solvent, dispersion agent, binding agents, by carrying out spray drying granulation behind certain proportioning weighing, the uniform mixing; Or broken, granulation after directly mixture being dried under≤90 ℃ temperature.
(2) dry-pressing formed: as, to be prepared into biscuit by pressure forming machine with definite shape and size with the powder after the granulation.
(3) binder removal: the product biscuit is placed the binder removal stove, under≤600 ℃ temperature, carry out binder removal in the air atmosphere and handle, with the various organism in the eliminating biscuit, thereby acquisition does not contain the biscuit of ceramics of residual carbon.
(4) high temperature sintering: the biscuit of ceramics behind the binder removal is placed High Temperature Furnaces Heating Apparatus, and according to the difference of ceramic formula, desirable 1700 ℃-1820 ℃ differing temps is carried out high temperature and is burnt till, and sintering time is 4-6 hour, finally obtains the aluminium nitride ceramics product.Sintering oven can be the graphite high temperature resistance furnace, also can be the tungsten high temperature vacuum resistance furnace.
Prepare the method for AlN ceramic substrate with doctor-blade casting process, comprise the steps:
(1) casting slurry preparation: with ceramic raw material, comprise AlN powder, sintering aid, liquid phase sintering auxiliary agent, with various organic additives, comprise that solvent, dispersion agent, binding agent, softening agent etc. are by certain proportioning weighing, utilize ball mill to carry out 36-48 hour uniform mixing, obtain elementary casting slurry by certain processing sequence.Then, elementary casting slurry is carried out froth in vacuum handle, make the casting slurry that is suitable for flow casting molding with certain viscosity.
(2) flow casting molding: casting slurry is prepared into curtain coating biscuit (sheet) band by casting machine.
(3) punching and shaping: with curtain coating biscuit (sheet) band punching and shaping is the biscuit sheet with definite shape and size.
(4) binder removal: the biscuit sheet is placed the binder removal stove, under≤600 ℃ temperature, carry out binder removal in the air atmosphere and handle, thereby acquisition does not contain the ceramic green sheet of residual carbon with the various organism in the eliminating biscuit.
(5) high temperature sintering: the ceramic green sheet behind the binder removal is placed High Temperature Furnaces Heating Apparatus, and according to the difference of ceramic formula, desirable 1700 ℃-1820 ℃ differing temps is carried out high temperature and is burnt till, and sintering time is 4-6 hour, finally obtains the aluminium nitride ceramics substrate.Sintering oven can be the graphite high temperature resistance furnace, also can be the tungsten high temperature vacuum resistance furnace.
In addition, hot pressing sintering method prepares the method for AlN ceramic substrate, and its forming method is consistent with dry pressuring forming process, only is that the sintering process employing is carried out under stressed state, but not normal pressure-sintered, comprises the steps:
(1) mixing of materials, granulation: with ceramic raw material, comprise AlN powder, sintering aid, liquid phase sintering auxiliary agent, with organic additives such as solvent, dispersion agent, binding agents, by carrying out spray drying granulation behind certain proportioning weighing, the uniform mixing; Or broken, granulation after directly mixture being dried under≤90 ℃ temperature.
(2) dry-pressing formed: as, to be prepared into biscuit by pressure forming machine with definite shape and size with the powder after the granulation.
(3) binder removal: the product biscuit is placed the binder removal stove, under≤600 ℃ temperature, carry out binder removal in the air atmosphere and handle, with the various organism in the eliminating biscuit, thereby acquisition does not contain the biscuit of ceramics of residual carbon.
(4) high temperature hot pressed sintering: the biscuit of ceramics behind the binder removal is placed the high temperature hot pressing furnace, according to the difference of ceramic formula, can be that 1700 ℃-1820 ℃, pressure are that high temperature burns till under the condition of 10-20MPa in sintering temperature, finally obtains the aluminium nitride ceramics product.
The present invention is different with in the past understanding or viewpoint, promptly it is believed that usually, and that is added is a small amount of as Y
2O
3, CaO, Li
2Oxide compound sintering aids such as O, can be under lower temperature with the AlN powder in a small amount of Al of being contained
2O
3(usually≤and 1wt%) react, produce liquid phase, promote densification sintering.And it is considered herein that a small amount of Al that is contained in the AlN powder
2O
3Mainly be that form with the AlN lattice oxygen exists, rather than with Al
2O
3Exist mutually, therefore be not enough to or be difficult under lower temperature and sintering aid such as Y
2O
3Or CaO forms liquid phase; If add as Y
2O
3Binary or the agent of polybasic composite sintering knot such as-CaO, or YF
3, CaF
2Deng fluorochemical sintering aid and the agent of polynary composite sintering knot thereof, or the polynary composite sintering knot agent of oxide compound and fluorochemical composition etc., though these itself can form liquid phase under lower temperature, can only form the low liquid phase that contains Al, so still can only take the means of high temperature sintering.And in the process of high temperature sintering,, fluorochemical lost the effect that helps burning owing to being easy to volatilize.The present invention is by adding an amount of nanometer Al
2O
3But, the deficiency that one side You mends its content; On the other hand, because the high reactivity of nano-powder, can be under lower temperature and as Y
2O
3, CaO, Li
2O, YF
3, CaF
2Deng the sintering aid reaction, directly form the liquid phase that contains Al.Contain the diffusion mass transfer that the Al liquid phase helps Al, therefore can realize the densification sintering of the AlN pottery under the lesser temps, so among the preparation method provided by the invention, sintering temperature can be reduced to 1700-1820 ℃.
In addition, the present invention is by adding a small amount of nanometer Al
2O
3Can obtain to have a small amount of and be evenly distributed on the liquid phase of AlN crystal grain triangle crystal boundary or the microstructure of second crystallization phases.This microstructure can not influence the thermal conductivity of AlN pottery significantly, but helps realizing the color consistency of the large-size substrate product produced in enormous quantities, improves the planeness of product, and surfaceness etc. improve the production qualification rate, reduce manufacturing cost.
The method for preparing aluminium nitride ceramics provided by the invention has the following advantages:
1, added a spot of nanometer Al in the AlN ceramic formula of the present invention
2O
3Powder, and with the castor-oil plant wet goods as dispersion agent, not only can obviously not influence the colloid property of casting slurry, and can obtain good, the mixed uniformly slurry of dispersing characteristic of nano aluminium oxide and aluminium nitride, improve the sintering activity of material.
2, added in the AlN ceramic formula provided by the invention on a small quantity as aluminium secondary butylate C
12H
27AlO
3, aluminum isopropylate C
9H
21AlO
3With aluminium acetylacetonate C
15H
21AlO
6In one or more the mixture in the organoaluminum, above-mentioned organoaluminum can be dissolved in the ethanol, butanone equal solvent of preparation casting slurry fully, equably.Because these organoaluminums in binder removal (≤600 ℃) process of AlN biscuit, decomposing oxidation can take place, thereby original position generate highly active nanometer Al
2O
3, and be evenly dispersed in the biscuit of AlN matrix.
3, nanometer Al
2O
3Or by aluminium secondary butylate C
12H
27AlO
3, aluminum isopropylate C
9H
21AlO
3With aluminium acetylacetonate C
15H
21AlO
6Deng organoaluminum through binder removal and generated in-situ nanometer Al
2O
3With Y
2O
3, CaO, Li
2Oxide compounds such as O, or YF
3, CaF
2Sintering aids such as fluorochemical can produce under≤1700 ℃ temperature and contain the Al liquid phase, and are evenly distributed on around the AlN particle, help realizing down in lower temperature (≤1800 ℃) densification sintering of AlN pottery; And, help improving the product performance such as color consistency, planeness and roughness of ceramic substrate because a small amount of liquid phase is evenly distributed in ceramic grain-boundary.
4, adopt the compositing formula of AlN pottery of the present invention not to be only applicable to the casting method production of AlN ceramic substrate, and be applicable to the production of the AlN pottery of method such as dry-pressing formed.
Embodiment
The invention will be further described below in conjunction with specific embodiment, but the present invention is not limited to following examples.
The preparation of the doctor-blade casting process AlN ceramic substrate of embodiment 1, interpolation nano aluminium oxide
Raw material: ceramic raw material comprises AlN powder, Y
2O
3Powder, CaCO
3Powder and nanometer Al
2O
3(D50=250nm) powder, mixing of materials and moulding organic additive comprise solvent butanone and dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C and plasticizer phthalic acid dibutylester (DBP), polyoxyethylene glycol (PEG).
AlN pottery compositing formula: AlN, Y
2O
3, CaO and nanometer Al
2O
3Weight percentage be respectively 94.0%, 5.0%, 0.8% and 0.2%.Wherein, CaO is in fact by CaCO
3Introduce CaCO
3Addition convert i.e. CaCO by the shared weight percent of CaO in its molecular formula
3Mole addition of mole addition and CaO identical.
The casting slurry preparation: the compositing formula by above-mentioned AlN pottery, adopt common casting molding processes, with AlN, Y
2O
3, CaCO
3With nanometer Al
2O
3With dehydrated alcohol, butanone, Viscotrol C, binding agent PBV, dibutyl phthalate (DBP), the polyoxyethylene glycol of certainweight per-cent, the ball milling that utilizes ball mill to carry out 48 hours, obtain the uniform elementary casting slurry of mixing of materials.Then, elementary slurry is carried out froth in vacuum handle, make and be suitable for the casting slurry that flow casting molding is used.Wherein, the consumption of dehydrated alcohol, butanone, Viscotrol C, binding agent PBV, dibutyl phthalate (DBP), polyoxyethylene glycol and the add-on in the existing method are in full accord.
Flow casting molding: casting slurry is prepared curtain coating biscuit (sheet) band by casting machine.
Punching and shaping: with curtain coating biscuit (sheet) punching and shaping is the biscuit sheet of certain size.
Binder removal: the biscuit sheet is placed the binder removal stove, under 580 ℃ temperature, carry out binder removal in the air atmosphere and handle,, obtain not contain the ceramic green sheet of residual carbon to get rid of the various organism in the biscuit.
High temperature sintering: the ceramic green sheet behind the binder removal is placed the graphite high temperature resistance furnace, and N flows
2Carry out 1760 ℃, 5 hours sintering of insulation under the gas atmosphere protection, obtain the aluminium nitride ceramics substrate.
The performance of prepared AlN ceramic substrate as 100 * 100 * 1mm size is as shown in table 1.
Table 1 adds the casting method moulding of nano aluminium oxide, the AlN ceramic substrate performance of 1760 ℃/5h sintering preparation
Project |
Performance |
Project |
Performance |
Volume density (g/cm
3)
|
3.32 |
Bending strength (MPa) |
330 |
Thermal conductivity [20 ℃] (W/mk) |
168 |
Dielectric strength (MV/m) |
15 |
Linear expansivity (10
-6/℃)
|
4.7×10
-6 |
Body resistivity (Ω cm) |
2×10
14 |
Roughness R
a(μm)
|
0.30 |
Specific inductivity |
8.8 |
Planeness [~/ 25 (length)] |
0.04 |
Dielectric loss [1MHz] |
5×10
-4 |
The preparation of the doctor-blade casting process AlN ceramic substrate of embodiment 2, interpolation aluminum isopropylate
Raw material: ceramic raw material comprises AlN powder, Y
2O
3Powder, aluminum isopropylate C
9H
21AlO
3, mixing of materials and moulding organic additive comprise solvent butanone and dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C and plasticizer phthalic acid dibutylester (DBP), polyoxyethylene glycol (PEG).
AlN pottery compositing formula: AlN, Y
2O
3And Al
2O
3Weight percentage be respectively 95.0%, 4.5%, 0.5%.Wherein, Al
2O
3In fact by aluminum isopropylate C
9H
21AlO
3Introduce aluminum isopropylate C
9H
21AlO
3Addition by Al in its molecular formula
2O
3Shared weight percent converts, i.e. C
9H
21AlO
3The mole addition be Al
2O
3Mole 2 times of addition.
The casting slurry preparation: the compositing formula by above-mentioned AlN pottery, adopt common casting molding processes, with AlN, Y
2O
3With dehydrated alcohol, butanone, Viscotrol C, binding agent PVB, dibutyl phthalate (DBP), the polyoxyethylene glycol of aluminum isopropylate and certainweight per-cent, the ball milling that utilizes ball mill to carry out 40 hours, obtain the uniform elementary slurry of mixing of materials.Then, elementary slurry is carried out froth in vacuum handle, make and be suitable for the casting slurry that flow casting molding is used.Wherein, the consumption of dehydrated alcohol, butanone, Viscotrol C, binding agent PVB, dibutyl phthalate (DBP), polyoxyethylene glycol and the add-on in the existing method are in full accord.
Flow casting molding: casting slurry is prepared curtain coating biscuit (sheet) band by casting machine.
Punching and shaping: with curtain coating biscuit (sheet) punching and shaping is the biscuit sheet of certain size.
Binder removal: the biscuit sheet is placed the binder removal stove, under 580 ℃ temperature, carry out binder removal in the air atmosphere and handle,, obtain not contain the ceramic green sheet of residual carbon to get rid of the various organism in the biscuit.
High temperature sintering: the ceramic green sheet behind the binder removal is placed tungsten vacuum high-temperature resistance furnace, and N flows
2/ H
21780 ℃, 4 hours sintering of insulation are carried out in the protection of gas mixture atmosphere down, obtain the aluminium nitride ceramics substrate.
The performance of prepared AlN ceramic substrate as 100 * 100 * 1mm size is as shown in table 2.
Table 2 adds the casting method moulding of aluminum isopropylate, the AlN ceramic substrate performance of 1780 ℃/4h sintering preparation
Project |
Performance |
Project |
Performance |
Volume density (g/cm
3)
|
3.31 |
Bending strength (MPa) |
340 |
Thermal conductivity [20 ℃] (W/mk) |
178 |
Dielectric strength (MV/m) |
15 |
Linear expansivity (10
-6/℃)
|
4.5×10
-6 |
Body resistivity (Ω cm) |
3×10
14 |
Roughness R
a(μm)
|
0.20 |
Specific inductivity |
8.6 |
Planeness [~/ 25 (length)] |
0.03 |
Dielectric loss [1MHz] |
4×10
-4 |
The preparation of the dry pressing AlN pottery of embodiment 3, interpolation nano aluminium oxide
Raw material: ceramic raw material comprises AlN powder, Y
2O
3Powder, CaF
2Powder, nano alumina powder jointed (D50=200nm), mixing of materials and moulding organic additive comprise solvent dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C.
AlN pottery compositing formula: AlN, Y
2O
3, CaF
2With nanometer Al
2O
3Weight percentage be respectively 96.0%, 2.8%, 0.5% and 0.7%.
The mixture preparation: the compositing formula by above-mentioned AlN pottery, adopt common dry pressuring forming process, with AlN, Y
2O
3, CaF
2With nanometer Al
2O
3With dehydrated alcohol, binding agent PVB, the dispersion agent Viscotrol C of certainweight per-cent, the mixing that utilizes ball mill to carry out 36 hours obtains mixed slurry.Broken, the granulation in mixed slurry oven dry back with obtaining obtains mixture, and is standby.Wherein, the consumption of dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C and the add-on in the existing method are in full accord.
Dry-pressing formed: the biscuit that mixture has definite shape and size by the pressure forming machine preparation.
Binder removal: the biscuit sheet under 580 ℃ temperature, is carried out binder removal in the air atmosphere.
High temperature sintering: the ceramic green sheet behind the binder removal is placed tungsten vacuum high-temperature resistance furnace, and N flows
2/ H
21780 ℃, 4 hours sintering of insulation are carried out in the protection of gas mixture atmosphere down, obtain aluminium nitride ceramics.
Prepared as
The performance of AlN pottery as shown in table 3.
Table 3 adds the performance of AlN pottery of dry-pressing formed, the 1780 ℃/4h sintering preparation of nano aluminium oxide
Project |
Performance |
Project |
Performance |
Volume density (g/cm
3)
|
3.30 |
Dielectric strength (MV/m) |
15 |
Thermal conductivity [20 ℃] (W/mk) |
174 |
Body resistivity (Ω cm) |
2×10
14 |
Linear expansivity (10
-6/℃)
|
4.4×10
-6 |
Specific inductivity |
8.7 |
Bending strength (MPa) |
340 |
Dielectric loss [1MHz] |
6×10
-4 |
The preparation of the dry pressing AlN pottery of embodiment 4, interpolation aluminum isopropylate
Raw material: ceramic raw material comprises AlN powder, Y
2O
3Powder, aluminum isopropylate C
9H
21AlO
3, mixing of materials and moulding organic additive comprise solvent dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C.
AlN pottery compositing formula: aluminium nitride AlN, yttrium oxide Y
2O
3And aluminium oxide Al
2O
3Weight percentage be respectively 97.5%, 1.5%, 1.0%.Wherein, Al
2O
3In fact by aluminum isopropylate C
9H
21AlO
3Introduce aluminum isopropylate C
9H
21AlO
3Addition by Al in its molecular formula
2O
3Shared weight percent converts, i.e. C
9H
21AlO
3The mole addition be Al
2O
3Mole 2 times of addition.
The mixture preparation: the compositing formula by above-mentioned AlN pottery, adopt common dry-pressing formed preparation of powder technology, by the compositing formula of above-mentioned AlN pottery, with AlN, Y
2O
3With aluminum isopropylate C
9H
21AlO
3With dehydrated alcohol, binding agent PVB, the dispersion agent Viscotrol C of certainweight per-cent, the mixing that utilizes ball mill to carry out 36 hours obtains mixed slurry.Ball milling is mixed broken, the granulation in slurry oven dry back that obtains, obtain mixture, standby.Wherein, the consumption of dehydrated alcohol, binding agent PVB, dispersion agent Viscotrol C and the add-on in the existing method are in full accord.
Dry-pressing formed: the biscuit that mixture has definite shape and size by the pressure forming machine preparation.
Binder removal: the biscuit sheet under 580 ℃ temperature, is carried out binder removal in the air atmosphere.
High temperature sintering: the ceramic green sheet behind the binder removal is placed the graphite high temperature resistance furnace, and N flows
2Carry out 1800 ℃, 6 hours sintering of insulation under the gas atmosphere protection, obtain aluminium nitride ceramics.
Prepared as
The performance of AlN pottery as shown in table 4.
Table 4 adds the AlN ceramic performance of dry-pressing formed, the 1800 ℃/6h sintering preparation of aluminum isopropylate
Project |
Performance |
Project |
Performance |
Volume density (g/cm
3)
|
3.29 |
Dielectric strength (MV/m) |
15 |
Thermal conductivity [20 ℃] (W/mk) |
173 |
Body resistivity (Ω cm) |
3×10
14 |
Linear expansivity (10
-6/℃)
|
4.4×10
-6 |
Specific inductivity |
8.6 |
Bending strength (MPa) |
340 |
Dielectric loss [1MHz] |
3×10
-4 |