CN102807389A - Preparation method for Si3N4-Si2N2O porous complex phase ceramic - Google Patents

Preparation method for Si3N4-Si2N2O porous complex phase ceramic Download PDF

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CN102807389A
CN102807389A CN2012103157903A CN201210315790A CN102807389A CN 102807389 A CN102807389 A CN 102807389A CN 2012103157903 A CN2012103157903 A CN 2012103157903A CN 201210315790 A CN201210315790 A CN 201210315790A CN 102807389 A CN102807389 A CN 102807389A
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complex phase
phase ceramic
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porous complex
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CN102807389B (en
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贾德昌
王胜金
杨治华
段小明
周玉
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Harbin Institute of Technology
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Harbin Institute of Technology
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Abstract

The invention provides a preparation method for Si3N4-Si2N2O porous complex phase ceramic and relates to a preparation method for porous complex phase ceramic. The invention solves the technical problems that the conventional preparation method for the Si3N4-Si2N2O porous complex phase ceramic is complex and SiO2 is remained in the final product easily. The preparation method comprises the following steps: 1, preparing raw materials; 2, preparing block materials; 3, preparing green bodies; 4, preparing porous structure green bodies; and 5, preparing the Si3N4-Si2N2O porous complex phase ceramic. The Si3N4-Si2N2O porous complex phase ceramic prepared by the method has bending strength of 132 to 267 MPa, breaking tenacity of 1.8 to 4.3 MPa.m1/2, actual density of 1.8 to 2.7 g/cm<3> and dielectric constant of 4.0 to 6.7, and can serve as a thermal protection material and a wave-transparent material applied in the fields of aerospace, mechanical industry and the like.

Description

A kind of Si 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic
Technical field
The present invention relates to the preparation method of porous complex phase ceramic.
Background technology
Ceramic foam is a kind of novel texture and ceramic material; Has the physical surface properties that volume density is little, specific surface area reaches uniqueness greatly; To the selective perviousness of liquids and gases medium; Have energy absorption or damping characteristic, and have distinctive high temperature resistant, corrosion-resistant, high chemicalstability of pottery and dimensional stability, it is used widely in filtration, purification separation, chemical industry catalytic carrier, many-sides such as sound absorption damping, senior lagging material and sensing material.
Si 3N 4Pottery has a series of good character, as HS, H.T., anticorrosive, wear-resisting, thermal shock resistance is good, high temperature creep-resisting excellent property etc.With respect to Si 3N 4Pottery, Si 2N 2The O pottery possesses excellent more high temperature oxidation resistance characteristics.Consider Si from the thermodynamics angle 2N 2O is unique stable compound in the Si-N-O ternary system, can with Si 3N 4Coexistence.Si 3N 4-Si 2N 2The O complex phase ceramic can combine Si on performance 3N 4Mechanical property and Si that pottery is excellent 2N 2The excellent antioxidant property of O pottery.Therefore, Si 3N 4-Si 2N 2The O complex phase ceramic receives extensive concern as the structure unit that is applied under high temperature, the abominable working conditions.
Si 3N 4-Si 2N 2The traditional preparation process method of O porous complex phase ceramic is: for example publication number is the Chinese invention patent of CN102229498 and CN101531538, all is with Si 3N 4And SiO 2Be raw material, through adding a small amount of M xO y(M=Al, Y, Li etc.), M under the hot conditions xO yWith part Si O 2The reaction solution phase, Si 3N 4In liquid phase dissolving and with wherein SiO 2Reaction generates Si 2N 2O, the hole in the material is introduced through the preparation method of common ceramic foam.Q.F.Tong, and et al. (J.Eur.Ceram.Soc., 27 (16), 2007,4767-72); S.Q.Li, and et al. (Ceram.Int., 35 (5), 2009,1851-4); R.K.Paul, and et al. (J.Mater.Sci., 42 (12), 2007,4701-6) wait the people in document, also to do similar report.Traditional with Si 3N 4Be feedstock production Si 3N 4-Si 2N 2There is following problem in the method for O porous complex phase ceramic: the extra interpolation SiO of needs 2, the preparation method is complicated, and is prone to residual Si O in the final product 2
Summary of the invention
The present invention will solve existing preparation Si 3N 4-Si 2N 2The preparation method that the method for O porous complex phase ceramic exists is complicated, and is prone to residual Si O in the final product 2Technical problem, thereby a kind of Si is provided 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic.
A kind of Si of the present invention 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic carries out according to the following steps:
One, takes by weighing Si 3N 4, Y 2O 3, Al 2O 3(NH 4) 2HPO 4, Si wherein 3N 4: Y 2O 3: Al 2O 3Mass ratio be (92～95): 4: 2, (NH 4) 2HPO 4Account for Si 3N 4, Y 2O 3And Al 2O 310～60vol.% of TV is to Si 3N 4, Y 2O 3And Al 2O 3Middle (the NH that adds 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 5～24h, obtains slurry;
Two, be to dry under 40～80 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 1～2min carries out premolding under the pressure of 20～30MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1～2min cold isostatic compaction obtains green compact under the pressure of 100～300MPa;
Four, with the green compact after the moulding in air furnace in 500～800 ℃ the calcining 1～2h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1～0.2MPa 2In hot-pressed sintering furnace, carry out pressureless sintering 1～3h in 1500～1800 ℃ under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The Si of the present invention's preparation 3N 4-Si 2N 2O porous complex phase ceramic has following advantage:
(1) utilizes (NH 4) 2HPO 4Decomposition, original position forms the hole in the green compact, behind sintering, is able to keep, and forms Si 3N 4-Si 2N 2Pore texture in the O complex phase ceramic is through (NH in the control raw material 4) 2HPO 4Size, shape and add-on, can regulate and control Si 3N 4-Si 2N 2The porosity of O complex phase ceramic and the size and dimension of hole;
(2) Si of the present invention's preparation 3N 4-Si 2N 2The O ceramic foam is by waiting axle shape α-Si 3N 4, long bar-shaped β-Si 3N 4With tabular Si 2N 2O three phase composites, mean pore size are 5～8 μ m;
(3) (NH 4) 2HPO 4Degradation production be Si in the complex phase ceramic 2N 2The generation of O provides O, Si 2N 2The growing amount of O phase is with (NH in the raw material 4) 2HPO 4The increase of addition and increasing, thereby can be through (NH in the control raw material 4) 2HPO 4The introducing amount and control Si 3N 4-Si 2N 2Si in the O complex phase ceramic 2N 2The content of O phase;
(4) the present invention need not extra interpolation SiO 2, make Si 2N 2The formation proceed step by step of O phase and material mesoporosity, the preparation method is simple, and noresidue SiO in the final product 2, be fit to the actual production of extensiveization;
(5) Si of the present invention's preparation 3N 4-Si 2N 2Bending strength 132～the 267MPa of O porous complex phase ceramic, fracture toughness property 1.8～4.3MPam 1/2, actual density 1.8～2.7g/cm 3, specific inductivity 4.0～6.7 can be used for the thermally protective materials and the electromagnetic wave transparent material in fields such as aerospace, mechanical industry.
Description of drawings
Fig. 1 is different (NH in the prepared raw material 4) 2HPO 4Si during addition 3N 4-Si 2N 2The XRD figure of O porous complex phase ceramic: Fig. 1 is a) for adding (NH in the test one prepared raw material 4) 2HPO 4The time Si 3N 4Porous complex phase ceramic XRD figure, Fig. 1 b) is (NH in the prepared raw material of test two 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3Si during the 10vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure, Fig. 1 c) is (NH in the prepared raw material of test three 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3Prepared Si during the 20vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure, Fig. 1 d) is (NH in the prepared raw material of test four 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3Si during the 30vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure, Fig. 1 e) is (NH in the prepared raw material of test five 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3Si during the 40vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure, wherein,
Figure GDA00002083095200031
Represent α-Si 3N 4, zero represents Si 2N 2O,
Figure GDA00002083095200032
Represent β-Si 3N 4
Fig. 2 is experiment three prepared Si 3N 4-Si 2N 2The low power SEM figure of O porous complex phase ceramic;
Fig. 3 is experiment three prepared Si 3N 4-Si 2N 2The high power SEM figure of O porous complex phase ceramic;
Fig. 4 is experiment three prepared Si 3N 4-Si 2N 2The TEM photo of O porous complex phase ceramic.
Embodiment
Embodiment one: a kind of Si in this embodiment 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic carries out according to the following steps:
One, takes by weighing Si 3N 4, Y 2O 3, Al 2O 3(NH 4) 2HPO 4, Si wherein 3N 4: Y 2O 3: Al 2O 3Mass ratio be (92～95): 4: 2, (NH 4) 2HPO 4Account for Si 3N 4, Y 2O 3And Al 2O 310～60vol.% of TV is to Si 3N 4, Y 2O 3And Al 2O 3Middle (the NH that adds 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 5～24h, obtains slurry;
Two, be to dry under 40～80 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 1～2min carries out premolding under the pressure of 20～30MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1～2min cold isostatic compaction obtains green compact under the pressure of 100～300MPa;
Four, with the green compact after the moulding in air furnace in 500～800 ℃ the calcining 1～2h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1～0.2MPa 2In hot-pressed sintering furnace, carry out pressureless sintering 1～3h in 1500～1800 ℃ under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The Si of this embodiment preparation 3N 4-Si 2N 2O porous complex phase ceramic has following advantage:
(1) utilizes (NH 4) 2HPO 4Decomposition, original position forms the hole in the green compact, behind sintering, is able to keep, and forms Si 3N 4-Si 2N 2Pore texture in the O complex phase ceramic is through (NH in the control raw material 4) 2HPO 4Size, shape and add-on, can regulate and control Si 3N 4-Si 2N 2The porosity of O complex phase ceramic and the size and dimension of hole;
(2) Si of this embodiment preparation 3N 4-Si 2N 2The O ceramic foam is by waiting axle shape α-Si 3N 4, long bar-shaped β-Si 3N 4With tabular Si 2N 2O three phase composites, mean pore size are 5～8 μ m;
(3) (NH 4) 2HPO 4Degradation production be Si in the complex phase ceramic 2N 2The generation of O provides O, Si 2N 2The growing amount of O phase is with (NH in the raw material 4) 2HPO 4The increase of addition and increasing, thereby can be through (NH in the control raw material 4) 2HPO 4The introducing amount and control Si 3N 4-Si 2N 2Si in the O complex phase ceramic 2N 2The content of O phase;
(4) this embodiment need not extra interpolation SiO 2, make Si 2N 2The formation proceed step by step of O phase and material mesoporosity, the preparation method is simple, and noresidue SiO in the final product 2, be fit to the actual production of extensiveization;
(5) Si of this embodiment preparation 3N 4-Si 2N 2Bending strength 132～the 267MPa of O porous complex phase ceramic, fracture toughness property 1.8～4.3MPam 1/2, actual density 1.8～2.7g/cm 3, specific inductivity 4.0～6.7 can be used for the thermally protective materials and the electromagnetic wave transparent material in fields such as aerospace, mechanical industry.
Embodiment two: what this embodiment and embodiment one were different is: Si in the step 1 3N 4Powder is the α type, and purity is 86～98%, and median size is 0.2～0.8 μ m, and other is identical with embodiment one.
Embodiment three: what this embodiment was different with one of embodiment one or two is: (NH in the step 1 4) 2HPO 4Particle diameter is 60～120 orders.Other is identical with one of embodiment one or two.
Embodiment four: what this embodiment was different with one of embodiment one to three is: the dispersion medium that adopts during batch mixing in the step 1 is an absolute ethyl alcohol, and the ball milling time is 24h, ball material mass ratio (1～1.5): 1.Other is identical with one of embodiment one to three.
Embodiment five: what this embodiment was different with one of embodiment one to four is: the incinerating temperature rise rate is lower than 2.5 ℃/min in the step 4.Other is identical with one of embodiment one to four.
Embodiment six: what this embodiment was different with one of embodiment one to five is: the incinerating temperature rise rate is 2 ℃/min in the step 4.Other is identical with one of embodiment one to five.
Embodiment seven: what this embodiment was different with one of embodiment one to six is: the agglomerating temperature rise rate is 10～30 ℃/min in the step 5.Other is identical with one of embodiment one to six.
Embodiment eight: what this embodiment was different with one of embodiment one to seven is: the agglomerating temperature rise rate is 20 ℃/min in the step 5.Other is identical with one of embodiment one to seven.
Through following verification experimental verification beneficial effect of the present invention:
Test one: this test is tested as a comparison, does not add (NH in the raw material 4) 2HPO 4, preparation Si 3N 4The porous complex phase ceramic, the preparation method realizes by following method:
One, takes by weighing that 94g purity is 95%, median size is the Si of 0.6 μ m 3N 4Powder, 4g Y 2O 3Powder and 2gAl 2O 3Powder does not add (NH 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 24h, ball material mass ratio 1.5: 1 obtains slurry;
Two, be to dry under 60 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 90s carries out premolding under the pressure of 20MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1min cold isostatic compaction obtains green compact under the pressure of 200MPa;
Four, with the vesicular structure green compact after the moulding in air furnace, in 2 ℃/min of temperature rise rate be warming up to 500 ℃ the calcining 1h, obtain the vesicular structure green compact;
Five, the green compact after will calcining at last are at the N of 0.1MPa 2In hot-pressed sintering furnace, be warming up to 1700 ℃ in 20 ℃/min of temperature rise rate and carry out pressureless sintering 2h under the protective atmosphere, obtain Si 3N 4The porous complex phase ceramic.
The real density of resultant vesicular structure green compact is 1.78g/cm in this testing sequence four 3
This is tested and adds (NH in the prepared raw material 4) 2HPO 4Si 3N 4Porous complex phase ceramic XRD figure as Fig. 1 a) shown in, a) can find out Si from Fig. 1 3N 4The porous complex phase ceramic is by α-Si 3N 4And β-Si 3N 4Form no Si 2N 2The O phase.The sintering linear shrinkage is 12.3%, and real density is 2.67g/cm 3, the ventilate rate is 13.3%, and bending strength is 433.2MPa, and fracture toughness property is 4.29MPam 1/2, the specific inductivity under 20GHz is 6.76.
Test two: a kind of Si of this test 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic realizes by following method:
One, takes by weighing that 94g purity is 95%, median size is the Si of 0.6 μ m 3N 4Powder, 4g Y 2O 3Powder and 2gAl 2O 3Powder is 100 purpose (NH to wherein adding the 10g particle diameter 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 24h, ball material mass ratio 1.5: 1 obtains slurry;
Two, be to dry under 60 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 90s carries out premolding under the pressure of 20MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1min cold isostatic compaction obtains green compact under the pressure of 200MPa;
Four, with the vesicular structure green compact after the moulding in air furnace, in 2 ℃/min of temperature rise rate be warming up to 500 ℃ the calcining 1h, obtain the vesicular structure green compact;
Five, the green compact after will calcining at last are at the N of 0.1MPa 2In hot-pressed sintering furnace, be warming up to 1700 ℃ in 20 ℃/min of temperature rise rate and carry out pressureless sintering 2h under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The real density of resultant vesicular structure green compact is 1.75g/cm in this testing sequence four 3
(the NH that adds in this test two 4) 2HPO 4Through calcining and decomposing, original position forms hole, (NH then in green compact 4) 2HPO 4Degradation production in the pressureless sintering process, can promote Si 2N 2The formation of O phase is promptly through adding (NH 4) 2HPO 4Just can make Si 2N 2The formation proceed step by step of O phase and material mesoporosity need not extra interpolation SiO 2, the preparation method is simple, and noresidue SiO in the final product 2
This tests two prepared (NH 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3The Si of TV 10vol.% 3N 4-Si 2N 2O porous complex phase ceramic XRD figure is like Fig. 1 b) shown in, from Fig. 1 b) can find out Si 3N 4-Si 2N 2O porous complex phase ceramic is by α-Si 3N 4, β-Si 3N 4And Si 2N 2O three phase composites, wherein Si 2N 2The content of O accounts for 20.3% of total molar content; The sintering linear shrinkage is 11.6%, and real density is 2.51g/cm 3, the ventilate rate is 15.5%, and bending strength is 266.2MPa, and fracture toughness property is 3.08MPam 1/2, the specific inductivity under 20GHz is 6.08.
Test three: a kind of Si of this test 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic realizes by following method:
One, takes by weighing that 94g purity is 95%, median size is the Si of 0.6 μ m 3N 4Powder, 4g Y 2O 3Powder and 2gAl 2O 3Powder is 100 purpose (NH to wherein adding the 20g particle diameter 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 24h, ball material mass ratio 1.5: 1 obtains slurry;
Two, be to dry under 60 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 90s carries out premolding under the pressure of 20MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1min cold isostatic compaction obtains green compact under the pressure of 200MPa;
Four, with the green compact after the moulding in air furnace, in 2 ℃/min of temperature rise rate be warming up to 500 ℃ the calcining 1h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1MPa 2In hot-pressed sintering furnace, be warming up to 1700 ℃ in 20 ℃/min of temperature rise rate and carry out pressureless sintering 2h under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The real density of resultant vesicular structure green compact is 1.69g/cm in this testing sequence four 3
(the NH that adds in this test three 4) 2HPO 4Through calcining and decomposing, original position forms hole, (NH then in green compact 4) 2HPO 4Degradation production in the pressureless sintering process, can promote Si 2N 2The formation of O phase is promptly through adding (NH 4) 2HPO 4Just can make Si 2N 2The formation proceed step by step of O phase and material mesoporosity need not extra interpolation SiO 2, the preparation method is simple, and noresidue SiO in the final product 2
This tests three prepared (NH 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3The Si of TV 20vol.% 3N 4-Si 2N 2O porous complex phase ceramic XRD figure is like Fig. 1 c) shown in, from Fig. 1 c) can find out Si 3N 4-Si 2N 2O porous complex phase ceramic is by α-Si 3N 4, β-Si 3N 4And Si 2N 2O three phase composites, wherein Si 2N 2The content of O accounts for 34.7% of total molar content; The sintering linear shrinkage is 10.3%, and real density is 2.25g/cm 3, the ventilate rate is 20.7%, and bending strength is 246.9MPa, and fracture toughness property is 2.72MPam 1/2, the specific inductivity under 20GHz is 5.34.
This tests three prepared Si 3N 4-Si 2N 2The low power SEM figure of O porous complex phase ceramic is as shown in Figure 2, as can beappreciated from fig. 2, and Si 3N 4-Si 2N 2Pore in the O porous complex phase ceramic distributes more even in matrix, and hole becomes random shape, and pore dimension is about 5～8 μ m.
This tests three prepared Si 3N 4-Si 2N 2The high power SEM figure of O porous complex phase ceramic is as shown in Figure 3, as can beappreciated from fig. 3, and Si 3N 4-Si 2N 2Si in the O porous complex phase ceramic 2N 2O crystal grain presents very regular plate-like structure, and thickness is about 0.7～1 μ m.
This tests three prepared Si 3N 4-Si 2N 2The TEM photo of O porous complex phase ceramic is as shown in Figure 4, as can beappreciated from fig. 4, and Si 2N 2O crystal grain middle part exists piling up dislocation.
Test four: a kind of Si of this test 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic realizes by following method:
One, takes by weighing that 94g purity is 95%, median size is the Si of 0.6 μ m 3N 4Powder, 4g Y 2O 3Powder and 2gAl 2O 3Powder is 100 purpose (NH to wherein adding the 30g particle diameter 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 24h, ball material mass ratio 1.5: 1 obtains slurry;
Two, be to dry under 60 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 90s carries out premolding under the pressure of 20MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1min cold isostatic compaction obtains green compact under the pressure of 200MPa;
Four, with the green compact after the moulding in air furnace, in 2 ℃/min of temperature rise rate be warming up to 500 ℃ the calcining 1h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1MPa 2In hot-pressed sintering furnace, be warming up to 1700 ℃ in 20 ℃/min of temperature rise rate and carry out pressureless sintering 2h under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The real density of resultant vesicular structure green compact is 1.65g/cm in this testing sequence four 3
(the NH that adds in this test four 4) 2HPO 4Through calcining and decomposing, original position forms hole, (NH then in green compact 4) 2HPO 4Degradation production in the pressureless sintering process, can promote Si 2N 2The formation of O phase is promptly through adding (NH 4) 2HPO 4Just can make Si 2N 2The formation proceed step by step of O phase and material mesoporosity need not extra interpolation SiO 2, the preparation method is simple, and noresidue SiO in the final product 2
This tests four prepared (NH 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3The Si of the 30vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure is like Fig. 1 d) shown in, from Fig. 1 d) can find out Si 3N 4-Si 2N 2O porous complex phase ceramic is by α-Si 3N 4, β-Si 3N 4And Si 2N 2O three phase composites, wherein Si 2N 2The content of O accounts for 43.1% of total molar content; The sintering linear shrinkage is 7.5%, and real density is 2.02g/cm 3, the ventilate rate is 28.5%, and bending strength is 175.8MPa, and fracture toughness property is 2.10MPam 1/2, the specific inductivity under 20GHz is 4.61.
Test five: a kind of Si of this test 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic realizes by following method:
One, takes by weighing that 94g purity is 95%, median size is the Si of 0.6 μ m 3N 4Powder, 4g Y 2O 3Powder and 2gAl 2O 3Powder is 100 purpose (NH to wherein adding the 40g particle diameter 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 24h, ball material mass ratio 1.5: 1 obtains slurry;
Two, be to dry under 60 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 90s carries out premolding under the pressure of 20MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1min cold isostatic compaction obtains green compact under the pressure of 200MPa;
Four, with the green compact after the moulding in air furnace, in 2 ℃/min of temperature rise rate be warming up to 500 ℃ the calcining 1h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1MPa 2In hot-pressed sintering furnace, be warming up to 1700 ℃ in 20 ℃/min of temperature rise rate and carry out pressureless sintering 2h under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
The real density of resultant vesicular structure green compact is 1.62g/cm in this testing sequence four 3
(the NH that adds in this test five 4) 2HPO 4Through calcining and decomposing, original position forms hole, (NH then in green compact 4) 2HPO 4Degradation production in the pressureless sintering process, can promote Si 2N 2The formation of O phase is promptly through adding (NH 4) 2HPO 4Just can make Si 2N 2The formation proceed step by step of O phase and material mesoporosity need not extra interpolation SiO 2, the preparation method is simple, and noresidue SiO in the final product 2
This tests five prepared (NH 4) 2HPO 4Addition accounts for Si 3N 4, Y 2O 3And Al 2O 3The Si of the 40vol.% of TV 3N 4-Si 2N 2O porous complex phase ceramic XRD figure is like Fig. 1 e) shown in, from Fig. 1 e) can find out Si 3N 4-Si 2N 2O porous complex phase ceramic is by α-Si 3N 4, β-Si 3N 4And Si 2N 2O three phase composites, wherein Si 2N 2The content of O accounts for 57.6% of total molar content; The sintering linear shrinkage is 6.0%, and real density is 1.84g/cm 3, the ventilate rate is 34.2%, and bending strength is 132.1MPa, and fracture toughness property is 1.81MPam 1/2, the specific inductivity under 20GHz is 4.08.
Can know through above-mentioned test: (NH 4) 2HPO 4Adding whether determining whether Si is arranged in the final product 2N 2The generation of O phase.There is not (NH in the raw material 4) 2HPO 4Add in fashionable, the prepared material and do not have Si 2N 2The generation of O phase is along with (NH in the raw material 4) 2HPO 4Add-on increase Si in the reaction product 2N 2The content of O phase is also increasing, and the density of material is reduced, and the ventilate rate raises.Therefore through regulating (NH in the raw material 4) 2HPO 4Addition, can make prepared Si 3N 4-Si 2N 2Density, the ventilate rate of O porous complex phase ceramic are controlled, Si 3N 4-Si 2N 2Si in the O porous complex phase ceramic 2N 2The content of O phase is adjustable.

Claims (6)

1. Si 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic is characterized in that Si 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic carries out according to the following steps:
One, takes by weighing Si 3N 4, Y 2O 3, Al 2O 3(NH 4) 2HPO 4, Si wherein 3N 4: Y 2O 3: Al 2O 3Mass ratio be (92～95): 4: 2, (NH 4) 2HPO 4Account for Si 3N 4, Y 2O 3And Al 2O 310～60vol.% of TV is to Si 3N 4, Y 2O 3And Al 2O 3Middle (the NH that adds 4) 2HPO 4, adopting absolute ethyl alcohol is that dispersion medium carries out ball mill mixing 5～24h, obtains slurry;
Two, be to dry under 40～80 ℃ of fluidizing air conditions slurry in temperature, the mixed powder after oven dry sieves, and pressurize 1～2min carries out premolding under the pressure of 20～30MPa, obtains block materials;
Three, take out block materials and put into rubber mold, bleed and encapsulate, pressurize 1～2min cold isostatic compaction obtains green compact under the pressure of 100～300MPa;
Four, with the green compact after the moulding in air furnace in 500～800 ℃ the calcining 1～2h, obtain the vesicular structure green compact;
Five, the vesicular structure green compact after will calcining at last are at the N of 0.1～0.2MPa 2In hot-pressed sintering furnace, carry out pressureless sintering 1～3h in 1500～1800 ℃ under the protective atmosphere, obtain Si 3N 4-Si 2N 2O porous complex phase ceramic.
2. a kind of Si according to claim 1 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic is characterized in that Si in the step 1 3N 4Powder is the α type, and purity is 86～98%, and median size is 0.2～0.8 μ m.
3. a kind of Si according to claim 1 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic is characterized in that (NH in the step 1 4) 2HPO 4Particle diameter is 60～120 orders.
4. a kind of Si according to claim 1 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic, when it is characterized in that in the step 1 batch mixing, the ball milling time is 24h, ball material mass ratio (1～1.5): 1.
5. a kind of Si according to claim 1 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic is characterized in that the incinerating temperature rise rate is lower than 2.5 ℃/min in the step 4.
6. a kind of Si according to claim 1 3N 4-Si 2N 2The preparation method of O porous complex phase ceramic is characterized in that the agglomerating temperature rise rate is 10～30 ℃/min in the step 5.
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CN109750351A (en) * 2018-05-31 2019-05-14 河北高富氮化硅材料有限公司 A kind of efficient Si of polycrystalline silicon ingot casting3N4Powder
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CN103755352A (en) * 2014-01-23 2014-04-30 哈尔滨工业大学 Preparation method of porous BN/Si3N4 composite ceramic hole sealing layer
CN105948783A (en) * 2016-01-14 2016-09-21 广东工业大学 Preparation method for preparing Si2N2O-Si3N4-TiN porous ceramics
CN105948783B (en) * 2016-01-14 2018-09-25 广东工业大学 A kind of Si2N2O-Si3N4The preparation method of-TiN porous ceramics
CN109750351A (en) * 2018-05-31 2019-05-14 河北高富氮化硅材料有限公司 A kind of efficient Si of polycrystalline silicon ingot casting3N4Powder
CN112140282A (en) * 2020-09-28 2020-12-29 中航装甲科技有限公司 Method for improving fluidity of silicon-based ceramic core slurry
CN112140282B (en) * 2020-09-28 2022-02-15 中航装甲科技有限公司 Method for improving fluidity of silicon-based ceramic core slurry

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