CN103058701A - Preparation method for porous silicon nitride composite ceramic - Google Patents
Preparation method for porous silicon nitride composite ceramic Download PDFInfo
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- CN103058701A CN103058701A CN2012105365652A CN201210536565A CN103058701A CN 103058701 A CN103058701 A CN 103058701A CN 2012105365652 A CN2012105365652 A CN 2012105365652A CN 201210536565 A CN201210536565 A CN 201210536565A CN 103058701 A CN103058701 A CN 103058701A
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Abstract
The invention relates to a preparation method for porous silicon nitride composite ceramic. In the preparation method, silicon nitride is used as a substrate, Al2O3 and Y2O3 are used as sintering aids, BN is used as an additive, and diatomite is used as a pore-forming agent. The preparation method comprises the following steps of performing ball milling and wet mixing on the raw materials in proportion; drying, screening, dry pressing and presintering mixed materials; sintering the mixed materials in a multifunctional sintering furnace under an N2 atmosphere, sintering to a specified temperature and preserving the heat for a period of time; and naturally cooling to a room temperature, and thus obtaining finished products. The prepared products have good performance, the porosity of porous silicon nitride can reach 51 percent and is increased by 20 percent compared with that of the porous silicon nitride without the diatomite, the bending strength can reach 86.46 MPa, and the fracture toughness can reach 1.41 MPa m1/2.
Description
Technical field
The present invention relates to a kind of diatomite and make the preparation method of the nitride porous Si composite ceramic of pore-forming material, belong to ceramic preparation method technical field.
Background technology
At present, pottery and ceramic matric composite have obtained paying close attention to greatly both at home and abroad with its excellent dielectric properties and mechanical property.Porous Si
3N
4Composite ceramics has excellent mechanical property, thermal shock resistance, fire performance, and lower specific inductivity, is the excellent candidate material of electromagnetic wave transparent material.
The preparation method that porous silicon nitride is commonly used has the organic foam method of forming, particle packing to form pore, gas foaming forms the methods such as vesicular structure, the pressureless sintering of interpolation pore-forming material.But these methods prepare the sample gas porosity and mechanical property can not get both.Organic foam material produces the sintering residue easily as a kind of intermediate, becomes obnoxious flavour in sintering process easily, causes environmental pollution; The void content of the standby porous material of particle packing legal system is lower, is generally about 20%～30%.
Application number: 200610041867.7 Chinese patent discloses a kind of porous SiN ceramic and preparation method thereof, by weight percentage, with following component: carbon, SiO 2 powder 75～95%, silicon nitride 1～10%, sintering aid 2～20% mixes; Wherein the weight ratio of carbon and silicon-dioxide is 0.4～0.6; Sintering aid comprises metal oxide Y
2O
3, Al
2O
3, MgO at least a; Above-mentioned initial powder is sieved after with dispersion agent ball milling drying, obtain mixed powder; Mixed powder is inserted in the mould, adopted pressure molding to obtain molding; Above-mentioned molding is put into atmosphere furnace, under nitrogen with 600 the degree/hour heat-up rate be heated to 1500 the degree, further with 180 the degree/hour heat-up rate be heated to the 1700-1800 degree, be to be incubated 2～8 hours under 6-10 the normal atmosphere at nitrogen pressure, namely obtain sintered compact.This patent adopts carbothermic reduction reaction to prepare porous silicon nitride, but has easily carbon residual in the sintered sample, and is unfavorable to ceramic performance; And sintering temperature is higher, and power consumption is large.
Application number: 200810017782.4 Chinese patent discloses a kind of silicon nitride porous ceramic composition and preparation method, by weight percentage, comprises following component: alpha-silicon nitride powders 50～70%, wilkinite 5～30%, sintering aid 0～10%, water 20～30%.Sintering aid comprises Y
2O
3, Al
2O
3Or MgO is at least a; Component weighing with beyond above-mentioned the dewatering places ball mill dry method mix grinding, obtains mixed powder, then mixed powder is placed the crushing mill rolling to mediate, and obtains pug; Pug put into carry out extrusion molding in the extrusion machine and obtain molding; To put into atmosphere furnace after the molding oven dry again, and be heated to the 1700-1850 degree with 10 heat-up rates of spending/dividing under nitrogen, be to be incubated 1～3 hour sintering under 1-6 the normal atmosphere at nitrogen pressure, namely obtains sintered compact.Contain more Na, Mg plasma in this patent agents useful for same wilkinite, limited ceramic range of application; Sintering temperature is higher simultaneously, and consumed energy is large.
Summary of the invention
For overcoming the deficiencies in the prior art, the invention provides a kind of preparation method of nitride porous Si composite ceramic, take the vesicular structure diatomite of cheapness as pore-forming material.Diatomite is the biomineral material that is formed by the remains deposition mineralization of waterplant diatom, and essence is unformed amorphousness SiO
2Because its biogenesis, have the microvoid structure of unique ordered arrangement, the advantage such as porosity is high, pore volume is large, quality is light, tap density is little, thermal conductivity is low, and it is widely distributed, cheap.
The technical scheme that the present invention takes is:
A kind of preparation method of nitride porous Si composite ceramic comprises that step is as follows:
(1) takes by weighing Si by weight 30 ~ 85:1 ~ 30:10 ~ 15:5
3N
4Matrix, diatomite pore-forming material, sintering aid and BN additive in the ball grinder of then packing into, use alumina balls, and ratio of grinding media to material is 5-7:1, and the 300-500r/min ball milling is 5 ~ 8 hours under the room temperature;
(2) mixed powder behind the ball milling is dried 200 mesh sieves after, adding additives stirs and places under mould 30 ~ 40MPa pressure dry-pressing formedly, drying is warming up to 600 ~ 700 ℃ with 3 ℃/min speed and carries out presintering in resistance furnace, insulation 1 ~ 2h;
(3) place multifunctional sintering furnace to be warming up to 1450～1550 ℃ with 10 ℃/min speed, at N
2Carry out sintering under the atmosphere, nitrogen pressure is to be incubated 1 ~ 2 hour under 1-5 the normal atmosphere, and stopped heating makes it naturally cool to room temperature in stove, obtains finished product.
Sintering aid described in the above-mentioned steps (1) is Al
2O
3And Y
2O
3, both mass ratioes are 1-1.5:1;
The described binding agent of step (2) is polyvinyl alcohol water solution (every 5g polyvinyl alcohol powder is dissolved in 100ml water, boils to clarification), and mixed powder and binding agent mass ratio are 15-20:1; Described drying means is 100～120 ℃ of drying 10～12h.
The gained finished product is through grinding, and the techniques such as cutting are carried out other performance test.
The intrinsic disc vesicular structure of diatomite stops the particle packing, sintering post shrinkage can pore-creating before sintering, the bonding that eutectic mixture helps to reduce between the particle is most advanced and sophisticated, increase the hole wall smoothness, can stop generation and the expansion of tiny crack, all will produce positive influence to ceramic hole structure and mechanical property, and SiO
2The phase transformation thing can not bring impurity, can not produce environment and pollute.The present invention adopts common pressureless sintering, and the equipment of use is comparatively simple, can prepare the porous silicon nitride ceramic of better performances under lower cost.
Beneficial effect of the present invention is: the equipment of use is simple and security good, and cost is lower, stable preparation process, and manipulation is simple, and production efficiency is high.Good product performance, the void content of porous silicon nitride can reach 51%, improves on year-on-year basis 20% than nothing diatomite, and flexural strength can reach 86.46MPa, and fracture toughness property can reach 1.41MPam
1/2
Description of drawings
Fig. 1 is the x-ray diffraction pattern of the diatomite pore-creating nitride porous silicon sample that makes of the present invention;
Fig. 2 (a) is diatomaceous shape appearance figure;
Fig. 2 (b) is the scanning electron microscope shape appearance figure of mixed powder;
The scanning electron microscope shape appearance figure of the sample that Fig. 2 (c) makes for the present invention;
The scanning electron microscope shape appearance figure of the sample that Fig. 2 (d) makes for the present invention;
Fig. 3 is the flexural strength curve of the diatomite pore-creating nitride porous silicon sample that makes of the present invention;
Fig. 4 is the fracture toughness property curve of the diatomite pore-creating nitride porous silicon sample that makes of the present invention;
Fig. 5 is the void content curve of the diatomite pore-creating nitride porous silicon sample that makes of the present invention.
Embodiment
Further specify below in conjunction with embodiment.
Embodiment 1
With 15g Si
3N
4, 1.2g Al
2O
3, 0.8g Y
2O
3, 1.0g BN and 2.0g diatomite puts into ball mill, take dehydrated alcohol as solvent, uses alumina balls, ratio of grinding media to material is 7:1, the 300r/min ball milling is 7 hours under the room temperature; Mixed powder behind ball milling oven dry is sieved behind 200 orders, and adding additives stirs and places mould, and is dry-pressing formed under 40MPa pressure, 100 ℃ of dry 12h, 700 ℃ of presintering in resistance furnace, insulation 1h; In multifunctional sintering furnace, be warming up to 1500 ℃ with 10 ℃/min, N
2Carry out sintering under the atmosphere, be incubated stopped heating after 1 hour, make it in stove, naturally cool to room temperature, obtain finished product.
Fig. 1 is the x-ray diffraction pattern of the porous material that makes of present embodiment.From figure diffraction peak as seen, matrix material is with α-Si
3N
4Be principal phase, and a small amount of β-Si is arranged
3N
4Generate, this conforms to fracture apperance figure observations.Grain-Boundary Phase is the mixture that some Si, Al, O, N form, and still keeps a small amount of SiO in the sample
2Phase; Because the BN add-on seldom, does not have the diffraction peak of BN to occur among the figure.
Fig. 2 (a) is complete diatomaceous shape appearance figure, and as seen it has the level and smooth butterfly structure of ordered arrangement micropore.Fig. 2 (b) is the shape appearance figure behind the wet ball-milling, can see still retaining part original appearance of diatomite, plays active effect to hindering the idiosome contraction.Fig. 2 (c) and 2(d) be the fracture shape appearance figure that makes sample, Fig. 2 (c) shows even pore distribution, porosity is high, and mostly be the small-bore structure, observe hole wall smooth structure (arrow indication) from Fig. 2 (d), bonding is most advanced and sophisticated between the particle reduces, diatomite is to reducing sintering shrinkage, increase porosity, reduce tiny crack generation and expansion and all will produce active effect, thereby improve porousness and the mechanical property of composite ceramics.
Fig. 3 and Fig. 4 are the flexural strength of the porous material that makes of present embodiment and the change curve of fracture toughness property.As seen, than without the diatomite sample, Mechanical Property of Ceramics descends to some extent when adding diatomite among the figure, mainly is because due to its void content raises.When increasing to 30% along with the diatomite addition by 5%, strength and toughness be first descend after increase trend, pore takes the lead in increasing rear minimizing simultaneously because diatomite adds when a small amount of, diatomite plays the pore-creating effect; Surpass Y when a certain amount of
2O
3, Al
2O
3And SiO
2The eutectic mixture that forms increases, and cohesive action increases, so void content descends again.With reference to figure 5 void content change curves, void content is maximum when adding 10% diatomite, reaches 51%, relatively improves 28.1% (without diatomite sample gas porosity 39.8%); Strength and toughness reaches respectively 78.04MPa and 1.25MPam simultaneously
1/2, relative reduce 22.2% (without diatomite sample 100.24MPa) and 33.9% is (without diatomite sample 1.89MPam
1/2).
Embodiment 2
Make matrix, Al with silicon nitride
2O
3And Y
2O
3Make sintering aid, BN is that additive, diatomite are made the pore-creating skeleton.Take by weighing Si with balance by proportioning
3N
415.75g, 1.26gAl
2O
3, 0.84gY
2O
3, 1.05gBN and 2.1g diatomite, in the planetary type ball-milling tank of packing into, dehydrated alcohol is solvent, uses alumina balls, ratio of grinding media to material is 7:1, the 300r/min ball milling is 6 hours under the room temperature; After mixed powder behind ball milling oven dry sieved, adding additives stirs and places the length of side was the mould of 42mm, dry-pressing formed under the 40MPa pressure, 100 ℃ of dry 12h, 700 ℃ of presintering in resistance furnace, insulation 1h; In multifunctional sintering furnace, be warming up to 1500 ℃ with 10 ℃/min, N
2Carry out sintering under the atmosphere, be incubated stopped heating after 1 hour, make it naturally cool to room temperature in stove, through grinding, the techniques such as cutting obtain finished product with the ceramic block that sinters.
Make matrix, Al with silicon nitride
2O
3And Y
2O
3Make sintering aid, BN is that additive, diatomite are made the pore-creating skeleton.Take by weighing Si with balance by proportioning
3N
413.02g, 1.20gAl
2O
3, 0.81gY
2O
3, 1.01gBN and 4.02g diatomite, in the planetary type ball-milling tank of packing into, dehydrated alcohol is solvent, uses alumina balls, ratio of grinding media to material is 7:1, the 300r/min ball milling is 6 hours under the room temperature; After mixed powder behind ball milling oven dry sieved, adding additives stirs and places the length of side was the mould of 42mm, dry-pressing formed under the 40MPa pressure, 100 ℃ of dry 12h, 700 ℃ of presintering in resistance furnace, insulation 1h; In multifunctional sintering furnace, be warming up to 1500 ℃ with 10 ℃/min, N
2Carry out sintering under the atmosphere, be incubated stopped heating after 1 hour, make it naturally cool to room temperature in stove, through grinding, the techniques such as cutting obtain finished product with the ceramic block that sinters.
Embodiment 4
Make matrix, Al with silicon nitride
2O
3And Y
2O
3Make sintering aid, BN is that additive, diatomite are made the pore-creating skeleton.Take by weighing Si with balance by proportioning
3N
411.03g, 1.20gAl
2O
3, 0.83gY
2O
3, 1.02gBN and 4.05g diatomite, in the planetary type ball-milling tank of packing into, dehydrated alcohol is solvent, uses alumina balls, ratio of grinding media to material is 7:1, the 300r/min ball milling is 6 hours under the room temperature; After mixed powder behind ball milling oven dry sieved, adding additives stirs and places the length of side was the mould of 42mm, dry-pressing formed under the 40MPa pressure, 100 ℃ of dry 12h, 700 ℃ of presintering in resistance furnace, insulation 1h; In multifunctional sintering furnace, be warming up to 1500 ℃ with 10 ℃/min, N
2Carry out sintering under the atmosphere, be incubated stopped heating after 1 hour, make it naturally cool to room temperature in stove, through grinding, the techniques such as cutting obtain finished product with the ceramic block that sinters.
Claims (4)
1. the preparation method of a nitride porous Si composite ceramic is characterized in that, comprises that step is as follows:
(1) takes by weighing Si by weight 30 ~ 85:1 ~ 30:10 ~ 15:5
3N
4Matrix, diatomite pore-forming material, sintering aid and BN additive in the ball grinder of then packing into, use alumina balls, and the 300-500r/min ball milling is 5 ~ 8 hours under the room temperature;
(2) mixed powder behind the ball milling is dried 200 mesh sieves after, adding additives stirs and places under mould 30 ~ 40MPa pressure dry-pressing formedly, drying is warming up to 600 ~ 700 ℃ with 3 ℃/min speed and carries out presintering in resistance furnace, insulation 1 ~ 2h;
(3) place multifunctional sintering furnace to be warming up to 1450 ~ 1550 ℃ with 10 ℃/min speed, at N
2Carry out sintering under the atmosphere, nitrogen pressure is to be incubated 1 ~ 2 hour under 1-5 the normal atmosphere, and stopped heating makes it naturally cool to room temperature in stove, obtains finished product.
2. the preparation method of a kind of nitride porous Si composite ceramic according to claim 1 is characterized in that, the sintering aid described in the step (1) is Al
2O
3And Y
2O
3, both mass ratio 1-1.5:1.
3. the preparation method of a kind of nitride porous Si composite ceramic according to claim 1 is characterized in that, the described binding agent of step (2) is polyvinyl alcohol water solution, and concentration is 0.05g/ml, and batch mixing and binding agent mass ratio are 15-20:1.
4. the preparation method of a kind of nitride porous Si composite ceramic according to claim 1 is characterized in that, the described drying means of step (2) is 100 ~ 120 ℃ of drying 10 ~ 12h.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105439620A (en) * | 2014-09-28 | 2016-03-30 | 盐城工学院 | Method for preparing porous silicon nitride by spark plasma sintering |
| CN105601319A (en) * | 2016-03-01 | 2016-05-25 | 中钢集团洛阳耐火材料研究院有限公司 | Method for preparing silicon carbide porous ceramics through low temperature sintering assisting |
| CN107963907A (en) * | 2017-11-21 | 2018-04-27 | 浙江师范大学 | A kind of sewage disposal sintered porous potsherd and preparation method thereof |
| CN108178657A (en) * | 2018-01-12 | 2018-06-19 | 上海均博复合材料科技有限公司 | A kind of high intensity wave transparent ceramic shield and preparation method thereof |
| CN108751968A (en) * | 2018-06-13 | 2018-11-06 | 北京科技大学 | A kind of porous ceramic film material preparation method of intrinsic pore-forming |
| CN112830796A (en) * | 2021-01-07 | 2021-05-25 | 盐城工学院 | Silicon nitride foamed ceramic for purifying water and preparation method thereof |
| CN113135761A (en) * | 2021-04-28 | 2021-07-20 | 白山市科学技术研究所 | Method for preparing silicon nitride ceramic from low-grade diatomite |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105439620A (en) * | 2014-09-28 | 2016-03-30 | 盐城工学院 | Method for preparing porous silicon nitride by spark plasma sintering |
| CN105601319A (en) * | 2016-03-01 | 2016-05-25 | 中钢集团洛阳耐火材料研究院有限公司 | Method for preparing silicon carbide porous ceramics through low temperature sintering assisting |
| CN107963907A (en) * | 2017-11-21 | 2018-04-27 | 浙江师范大学 | A kind of sewage disposal sintered porous potsherd and preparation method thereof |
| CN108178657A (en) * | 2018-01-12 | 2018-06-19 | 上海均博复合材料科技有限公司 | A kind of high intensity wave transparent ceramic shield and preparation method thereof |
| CN108178657B (en) * | 2018-01-12 | 2021-02-02 | 上海均博复合材料科技有限公司 | High-strength wave-transparent ceramic cover and preparation method thereof |
| CN108751968A (en) * | 2018-06-13 | 2018-11-06 | 北京科技大学 | A kind of porous ceramic film material preparation method of intrinsic pore-forming |
| CN108751968B (en) * | 2018-06-13 | 2020-12-22 | 北京科技大学 | Preparation method of intrinsic pore-forming porous ceramic material |
| CN112830796A (en) * | 2021-01-07 | 2021-05-25 | 盐城工学院 | Silicon nitride foamed ceramic for purifying water and preparation method thereof |
| CN113135761A (en) * | 2021-04-28 | 2021-07-20 | 白山市科学技术研究所 | Method for preparing silicon nitride ceramic from low-grade diatomite |
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Application publication date: 20130424 |