CN101407421B - Method for preparing non-grain boundary phase porous silicon nitride ceramic based on siliconizing nitridation - Google Patents
Method for preparing non-grain boundary phase porous silicon nitride ceramic based on siliconizing nitridation Download PDFInfo
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- CN101407421B CN101407421B CN2008102320992A CN200810232099A CN101407421B CN 101407421 B CN101407421 B CN 101407421B CN 2008102320992 A CN2008102320992 A CN 2008102320992A CN 200810232099 A CN200810232099 A CN 200810232099A CN 101407421 B CN101407421 B CN 101407421B
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Abstract
The invention discloses a method for preparing non-crystal boundary phrase porous silicon nitride ceramics based on siliconizing nitridation, which comprises the following steps: according to weight percent, the components of 93-95 wt percent of silicon nitride and 5-7 wt percent of sintering aid are mixed, and a porous silicon nitride sample with 35-55 percent of porosity is obtained by the conventional preparation technology for porous silicon nitride. The glass phases of the silicon nitride and the compounds formed by the sintering aid are removed by hydrofluoric acid, nitric acid and sulphuric acid; the sample undergoing acid cleaning is put in a vacuum furnace to insulate heat in vacuum for 20-40 minutes at 1550-1700 DEG C; after 5-10 wt percent of silicon is permeated, the sample is put into an atmosphere furnace of 1250-1390 DEG C to insulate heat for 4-8h to be nitridized, and then the sample is further insulated for 1-2 hours under the conditions that the temperature is 1750-1800 DEG C and the nitrogen pressure is between 3 to 6 atmospheric pressures to obtain the non-crystal boundary phrase porous silicon nitride ceramics. The porous ceramics can be widely applied to the base materials of filters used for separating gas in high temperature and corrosive atmospheres, and the high temperature heat resisting materials used by gas turbines used for generating power, engines, space shuttles, and the like.
Description
Technical field
The present invention relates to the preparation method of porous silicon nitride ceramic, relate in particular to a kind of method for preparing non-grain boundary phase porous silicon nitride ceramic based on siliconizing nitridation.
Background technology
Porous silicon nitride has excellent mechanical property such as high-wearing feature, high anti-complaisance and traumatic resistance, can be applied to strainer, support of the catalyst and bio-reactor under the high low temperature, and the enhancing of matrix material equates in the every field.Porous silicon nitride also has good thermostability, lower specific inductivity, low-dielectric loss, high erosive wear resistance, is regarded as most promising electromagnetic wave transparent material of new generation.Silicon nitride is the strong covalent bond compound, and its self-diffusion coefficient is very little, and necessary volume diffusion of densification and crystal boundary velocity of diffusion are very little, simultaneously its crystal boundary energy V
GbWith powder surface energy V
Sv, ratio (V
Gb/ V
Sv) more much bigger than ionic compound and metal, make that sintering motivating force △ V is less, therefore pure silicon nitride is difficult to by solid state sintering, the silicon-dioxide zone of oxidation or the silicon nitride that must add sintering aid (normally metal oxide) and alpha-silicon nitride powders surface form low-melting congruent melting liquid, have promoted SINTERING FOR SILICON NITRIDE CERAM and densification by liquid phase sintering mechanism.So far, the porous silicon nitride ceramic preparation is adopted and is added MgO, Al
2O
3, Y
2O
3, Yb
2O
3Produce liquid phase sintering Deng the oxidesintering auxiliary agent, and method such as carbothermic reduction.The molding of opening the mixed powder formation that will contain silicon nitride particle and oxidesintering auxiliary agent among the 2000-225985 as the Japanese Patent spy heats in nitrogen, and the addition of control sintering temperature and sintering aid obtains silicon nitride porous ceramic material.
Owing to add sintering aid,, form the porous silicon nitride ceramic that contains glassy phase among the above preparation method by liquid phase sintering.Owing to contain more glassy phase, hot strength is lower, and at high temperature glassy phase is easily softening, so its high thermal resistance, performances such as insulativity all have certain influence.
Summary of the invention
The preparation method who the purpose of this invention is to provide a kind of non-grain boundary phase porous silicon nitride ceramic improves the high-temperature behavior of existing porous silicon nitride ceramic and uses.
For reaching above purpose, the present invention takes following technical scheme to be achieved:
A kind ofly prepare the method for non-grain boundary phase porous silicon nitride ceramic, comprise the steps: based on siliconizing nitridation
(1) by weight percentage, with following component: silicon nitride 93～95%, sintering aid 5～7% mix, and the preparation technology of porous silicon nitride routinely is at N
2In 1750 times sintering 2h, obtaining void content is the porous silicon nitride sample of 35-55% in the atmosphere;
(2) remove glassy phase and the formed compound of sintering aid in the porous silicon nitride sample with more than one pickling of hydrofluoric acid, nitric acid, sulfuric acid, acid is removed in alkali cleaning again, prepares the silicon nitride matrix sample of no crystal boundary;
(3) the nitride porous silicon substrate sample after the pickling is put into the crucible that fills the silicon grain, place 1550～1700 ℃ of vacuum ovens to vacuumize the silicon that 5～10wt% was infiltrated in insulation in 20～40 minutes, silicon nitride matrix sample after the siliconising is placed the atmosphere furnace nitrogenize again, nitriding temperature is 1250～1390 ℃, soaking time 4～8h
(4) be to be incubated 1～2 hour under 3～6 normal atmosphere at 1750～1800 ℃ of nitrogen pressures afterwards, promptly obtain non-grain boundary phase porous silicon nitride ceramic.
In the aforesaid method, described sintering aid is at least a of aluminum oxide or trivalent rare earth metals oxide compound.Described pickling is the HNO with HF acid+98% of mass concentration 96%
3Acid, 60 ℃ of water-bath 2～4h remove glassy phase; H with mass concentration 98%
2SO
4Acid, 60 ℃ of water-bath 1h remove the compound of yttrium.Described alkali cleaning is to use the ammoniacal liquor of mass concentration 28%, and 69 ℃ of 1h remove acid.Vacuum meter indicating value in the described vacuum carburization step is-0.05～-0.1.In the described nitriding step, be with 5～30 degree/minute heat-up rate feed nitrogen when being heated to 800 ℃, nitrogen flow is 1.0～1.5Lmin
-1, be warming up to 1250～1390 ℃ after half an hour,
The present invention utilizes the silicon nitride that sinters to be the matrix sample, has guaranteed the skeleton of silicon nitride rod-like structure, utilizes the siliconising direct nitridation method to prepare the non-grain boundary phase porous silicon nitride ceramic that the silicon nitride that makes new advances is taken knot then.
The invention has the beneficial effects as follows, according to method of the present invention,, infiltrate controlled silicon amount by controlled temperature and time of vacuumizing, again by adjusting nitriding temperature and nitrogen pressure, the non-grain boundary phase porous silicon nitride ceramic that can obtain having high porosity and good mechanical behavior under high temperature.Non-grain boundary phase porous silicon nitride ceramic of the present invention, compare with existing porous silicon nitride ceramic,, have excellent high-temperature behavior owing to there is not the crystal boundary glassy phase, the body material that can be widely used in the gas delivery usefulness strainer under high-temperature atmosphere and the aggressive atmosphere, internal combustion turbine is used in generating, engine, the strengthening material of the heat-stable material that space shuttle etc. use, the strengthening material of metal-base composites, and various thermal insulation, sound-absorbing, substrate etc.
Description of drawings
Fig. 1 is the SEM figure after the example 7 sample siliconisings.
Fig. 2 is the XRD figure after the example 7 sample nitrogenize.
Fig. 3 is the SEM figure after the example 7 sample nitrogenize.
Embodiment
The present invention is described in further detail below in conjunction with specific embodiment.
Porous silicon nitride ceramic, its composition is as shown in table 1, in the embodiment shown in the table 1 1～9, alpha-silicon nitride powders content is generally at 93～95wt%, the addition of sintering aid is 5～7wt%, addition surpasses 7wt%, and the shrinking percentage of porous ceramics strengthens, and causes reducing and a large amount of intergranular glassy phases of void content.Sintering aid is meant the metal oxide that is varied to glassy phase in agglomerating high temperature field, can be expressed as M2O3 or MO (M is a metal), comprises that also a kind of oxide compound of or several compositions can become the mixture of glassy phase by reaction.The Y that adopts among such metal oxide such as table 1 embodiment
2O
3, Al
2O
3, Eu
2O
3Or Lu
2O
3At least a, according to circumstances also can add several hopcalites.
The preparation method of porous silicon nitride: silicon nitride is mixed the ball grinder of packing into sintering aid by the proportioning of table 1, is ball-milling medium with the dehydrated alcohol, with silicon nitride abrading-ball ball milling 24h on rotary mill.Mixed slip is dry in 60 ℃ of loft drier, cross 200 mesh sieves.The powder for preparing is pressed into bar-shaped sample at the pressure forming machine single shaft, then the green compact that press is being put in a plumbago crucible that scribbles BN, plumbago crucible is put into Japan produce the HIGH-MULTI-5000 multifunctional furnace at N
2In 1750 ℃ of following sintering 2h, the acquisition void content is 35～55% porous silicon nitride sample in the atmosphere.
The silicon nitride matrix preparation method of sample of no crystal boundary: be 35～55% porous silicon nitride sample with table 1 embodiment 1-embodiment 9 preparation void content with 96% dense HF acid+98% dense HNO
3Acid, 60 ℃ of temperature, water-bath 2～4h, glassy phase is removed in pickling; 98% dense H
2SO
4Acid, 60 ℃ of 1h, the compound of yttrium is removed in pickling; 28% dense ammonia, 69 ℃ of temperature, time 1h, acid is removed in alkali cleaning, prepares the silicon nitride matrix sample of no crystal boundary.
Silicon nitride is put in the crucible that fills the silicon grain, put into vacuum oven, vacuumize, the indicating value of vacuum meter is-0.05～-0.1 intensification, is raised to the silicon that 1550～1700 ℃ of vacuum heat-preservings infiltrated about 5～10wt% in 20～40 minutes.
Silicon nitride matrix sample after the siliconising is put into multi-functional atmosphere stove, with 5～30 degree/minute 800 ℃ of heat-up rate heating, feed nitrogen, nitrogen flow is 1.0～1.5Lmin
-1Rise to 1250～1390 ℃ after half an hour, soaking time 4～8h, be to be incubated 1～2 hour under 3～6 normal atmosphere at 1750～1800 ℃ of nitrogen pressures afterwards, obtain non-grain boundary phase porous silicon nitride ceramic with almost same void content of former sintered sample and strength level.
With electronics balance measurement sample mass, three-point bending method is measured flexural strength.Archimedes's drainage is measured the ventilate rate.X-ray diffraction (XRD) instrument analyte phase.Observe the microstructure of sample with scanning electron microscope (SEM).Table 1 is composition, void content and the bending strength of the embodiment of the invention 1～9, and table 2 is thermal treatment process conditions of the embodiment of the invention 1～9, and table 3 the present invention does not have the test performance of crystal boundary porous silicon nitride ceramic.SEM after example 7 sample siliconisings figure as shown in Figure 1, the XRD figure of sample as shown in Figure 2, the SEM after the nitrogenize is as shown in Figure 3.
Composition, void content and the bending strength of table 1 embodiment of the invention 1-9
| Example | Proportioning | Void content (%) | Bending strength (MPa) |
| Embodiment 1 | 95％Si 3N 4+5％Y 2O 3 | 53.13 | 139.2 |
| Embodiment 2 | 94％Si 3N 4+5％Y 2O 3+1％Al 2O 3 | 42.39 | 197.2 |
| Embodiment 3 | 93％Si 3N 4+5％Y 2O 3+2％Al 2O 3 | 35.05 | 216.8 |
| Embodiment 4 | 95％Si 3N 4+5％Lu 2O 3 | 54.06 | 148.3 |
| Embodiment 5 | 94％Si 3N 4+5％Lu 2O 3+1％Al 2O 3 | 44.35 | 206.3 |
| Embodiment 6 | 93％Si 3N 4+5％Lu 2O 3+2％Al 2O 3 | 37.12 | 234.2 |
| Embodiment 7 | 95％Si 3N 4+5％Lu 2O 3 | 53.65 | 143.4 |
| |
94％Si 3N 4+5％Lu 2O 3+1％Al 2O 3 | 43.12 | 217.5 |
| Embodiment 9 | 93％Si 3N 4+5％Lu 2O 3+2％Al 2O 3 | 36.67 | 229.4 |
The thermal treatment process condition of table 2 embodiment of the invention 1-9
| Example | Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | Embodiment 5 | Embodiment 6 | Embodiment 7 | |
Embodiment 9 |
| The siliconising temperature/℃ | 1550 | 1550 | 1550 | 1600 | 1600 | 1600 | 1650 | 1650 | 1700 |
| Vacuum heat-preserving time/min | 40 | 40 | 40 | 30 | 30 | 30 | 20 | 20 | 20 |
| Nitriding temperature/℃ | 1250 | 1250 | 1250 | 1320 | 1320 | 1320 | 1390 | 1380 | 1380 |
| Soaking time/h | 6 | 6 | 8 | 6 | 6 | 8 | 4 | 6 | 8 |
| High-temperature temperature/℃ | 1750 | 1750 | 1750 | 1750 | 1750 | 1750 | 1800 | 1800 | 1800 |
| Soaking time/h | 1 | 1 | 1 | 1.5 | 1.5 | 1.5 | 2 | 2 | 2 |
| Nitrogen pressure/atm | 6 | 6 | 6 | 4 | 3 | 4 | 5 | 5 | 5 |
The test performance of table 3 porous silicon nitride ceramic of the present invention
As can be seen from Table 1: along with the increase of sintering aid addition, volumetric shrinkage increases, and void content reduces, and intensity increases.
As shown in Table 2: substrate quality reduces 5～10% after the pickling, and void content increases about 2%.The sample weightening finish is 5～10% after the siliconising, and the sample weightening finish is 5～8% behind the sintering, has filled up the quality that erodes basically.After the sample corrosion, connect the interstructural glassy phase of silicon nitride rod-like and be corroded, only remaining club shaped structure, and between overlap joint not, intensity reduces, and almost reduces to half of original intensity.After the matrix sample infiltrated silicon, by the direct nitrogenizing reaction generation silicon nitride of silicon, the bar-shaped silicon nitride after the corrosion was overlapped again, and intensity raises.
Fig. 1 is as can be seen: the lamellar structure silicon of infiltration is evenly distributed between bar-shaped silicon nitride tissue.
Fig. 2 can show: have only β-Si among the figure
3N
4Diffraction peak, illustrate that the principal constituent of sample is β-Si after the nitrogenize
3N
4, the silicon and the nitrogen complete reaction of infiltrating the matrix sample generate silicon nitride.
Fig. 3 is as can be seen: newly-generated silicon nitride rod-like tissue has been filled up the space of the intergranular phase that erodes, and makes original silicon nitride rod-like tissue overlap joint mutually, has improved the intensity of sample, therefore can prepare the porous silicon nitride ceramic of no crystal boundary phase.
Claims (4)
1. one kind prepares the method for non-grain boundary phase porous silicon nitride ceramic based on siliconizing nitridation, it is characterized in that, comprises the steps:
(1) by weight percentage, with following component: silicon nitride 93～95%, sintering aid 5～7% mix, and the preparation technology of porous silicon nitride routinely is at N
2In 1750 ℃ of following sintering 2h, obtaining void content is the porous silicon nitride sample of 35-55% in the atmosphere;
(2) remove glassy phase and the formed compound of sintering aid in the porous silicon nitride sample with more than one pickling of hydrofluoric acid, nitric acid, sulfuric acid, acid is removed in alkali cleaning again, prepares the silicon nitride matrix sample of no crystal boundary;
(3) the nitride porous silicon substrate sample after the pickling is put into the crucible that fills the silicon grain, place 1550～1700 ℃ of vacuum ovens to vacuumize the silicon that 5～10wt% was infiltrated in insulation in 20～40 minutes, silicon nitride matrix sample after the siliconising is placed the atmosphere furnace nitrogenize again, nitriding temperature is 1250～1390 ℃, soaking time 4～8h
(4) be to be incubated 1～2 hour under 3～6 normal atmosphere at 1750～1800 ℃ of nitrogen pressures afterwards, promptly obtain non-grain boundary phase porous silicon nitride ceramic.
2. as claimed in claim 1ly prepare the method for non-grain boundary phase porous silicon nitride ceramic, it is characterized in that described sintering aid is at least a of aluminum oxide or trivalent rare earth metals oxide compound based on siliconizing nitridation.
3. as claimed in claim 1ly prepare the method for non-grain boundary phase porous silicon nitride ceramic based on siliconizing nitridation, it is characterized in that described alkali cleaning is to use the ammoniacal liquor of mass concentration 28%, 69 ℃ of 1h remove acid.
4. as claimed in claim 1ly prepare the method for non-grain boundary phase porous silicon nitride ceramic, it is characterized in that based on siliconizing nitridation, in the described nitriding step, be with 5～30 degree/minute heat-up rate feed nitrogen when being heated to 800 ℃, nitrogen flow is 1.0～1.5Lmin
-1, be warming up to 1250～1390 ℃ after half an hour.
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| CN101734925B (en) * | 2009-12-04 | 2012-02-01 | 西安交通大学 | Silicon nitride porous ceramics with controllable porosity and preparation method thereof |
| CN102757237B (en) * | 2012-06-28 | 2013-11-06 | 航天材料及工艺研究所 | Method for adding ceramic material sintering aid |
| CN105254306A (en) * | 2015-09-30 | 2016-01-20 | 西北工业大学 | Method for preparing high-thermal-conductivity silicon nitride ceramics |
| CN111094212A (en) * | 2017-09-12 | 2020-05-01 | 杰富意钢铁株式会社 | Refractory for siliconizing treatment furnace |
| CN109721370B (en) * | 2019-03-05 | 2022-02-18 | 青岛瓷兴新材料有限公司 | Silicon nitride, ceramic slurry and preparation method |
| CN112898040B (en) * | 2021-02-04 | 2022-05-06 | 西安交通大学 | Method for preparing intercrystalline-free glass phase beta-Si by using high length-diameter ratio whisker3N4Method for producing porous ceramics |
| CN115504808B (en) * | 2022-11-01 | 2023-09-19 | 中钢集团洛阳耐火材料研究院有限公司 | Preparation method of BN nozzle for gas atomization |
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