CN1026482C - Making method of crystal whisker excess weld metal silicon nitride compound material - Google Patents

Making method of crystal whisker excess weld metal silicon nitride compound material Download PDF

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CN1026482C
CN1026482C CN 91100598 CN91100598A CN1026482C CN 1026482 C CN1026482 C CN 1026482C CN 91100598 CN91100598 CN 91100598 CN 91100598 A CN91100598 A CN 91100598A CN 1026482 C CN1026482 C CN 1026482C
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temperature
sic
crystal whisker
strength
weld metal
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CN 91100598
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CN1052652A (en
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柳光祖
宋慎泰
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Central Iron and Steel Research Institute
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Central Iron and Steel Research Institute
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Abstract

The present invention belongs to a manufacturing method of silicon carbide crystal whisker excess weld metal silicon nitride composite materials, which uses Si3N4, SiO2, carbon black and an agglutinant aid as raw materials to synthesize a SiC crystal whisker at the temperature of 1500 to 1900 DEG C and the pressure of 1.1 to 10 atm N2. The SiC crystal whisker is then decarbonized at the temperature of 600 to 700 DEG C. The composite raw material of carbon elimination is hot pressed for 0.5 to 2 hours at the temperature of 1700 to 1900 DEG C and the atmosphere of N2, and a compact Si3N4-SiC (w) composite material is obtained. The fracture toughness of the composite material obtained by the present invention is 8.0MPa. m1/2, and the strength of the composite material is 670MPa at a normal temperature. After being oxidized for 100 hours at the temperature of 1300 DEG C, the measured high temperature strength of the composite material is 621MPa at the temperature of 1300 DEG C. Compared with the strength at the normal temperature, the strength is decreased by 7.3%.

Description

Making method of crystal whisker excess weld metal silicon nitride compound material
The invention belongs to a kind of manufacture method of silicon carbide whisker excess weld metal silicon nitride compound material.High temperature resistant, corrosion-resistant, the wear-resisting structural timber that undermines performance such as anti-oxidant can be made with this method, products such as engine component, lathe tool, wortle can be used for manufacturing.
At present, the crystal whisker excess weld metal matrix material methods that add whisker that adopt more, but since whisker itself be worth expensive, the matrix material price height that obtains, the restriction of being originated again, and need very complicated technology whisker is handled and disperseed; Therefore, how obtaining in preparation process the matrix material that self generates the some amount whisker, is one of striving direction of people.Japanese Patent J63-182254 discloses a kind of crystal whisker excess weld metal Al 2O 3The manufacture method of molding is with Al 2O 3, SiO 2React at 1600 ℃ with carbon black; Be SiO 2+ 3C → SiC (w)+ 2CO ↑, like this, matrix Al 2O 3Can not participate in the reaction and change, can obtain Al 2O 3Base SiC metal whisker composite.For Si 3N 4Base SiC metal whisker composite J63-64969,64970,64971 disclose a series of Si 3N 4-SiC (w)The manufacture method of sintered compact is with Si powder or Si powder and Si 3N 4Be raw material, adopt at N 2Reaction sintering is prepared Si earlier in the atmosphere 3N 4The matter base substrate is then at C 3H 8+ H 2+ H 2Synthetic SiC whisker in the mixed gas of S adopts the gas pressure sintering method to prepare fine and close matrix material at last, and performance is δ b～750MPa, K IC～8.0MPam 1/2, but do not see and introduce high-temperature behavior.This technological process is complicated, and source of the gas requires harsh, so its enforcement and application are subjected to certain limitation.
Purpose of the present invention is intended to overcome the shortcoming of above-mentioned prior art, and it is simple, easy to implement to obtain a kind of technology, and can obtain the manufacture method of the matrix material of higher high-temperature behavior.
For achieving the above object, the present invention is achieved in that Si 3N 4, SiO 2, powder mixes such as carbon black and sintering aid, at certain temperature (1500～1900 ℃), certain N 2Pressure (1.1～10atm) times synthetic SiC whiskers, decarburization 1～3h in 600～700 ℃, air then.In 1700～1900 ℃ of following hot pressing 0.5～2h, can obtain Si again 3N 4-SiC (w)Matrix material.
Below the present invention is described in further detail.
The Si that the present invention obtains 3N 4-SiC (w)The manufacture method of matrix material is: with weight ratio is 50～70%Si 3N 4(granularity＜0.3 μ m), 15～25%SiO 2(granularity＜100 μ m), 10～20% carbon blacks, 3～8% sintering aids mix in anhydrous ethanol medium, sieve after the oven dry.This mixing raw material is packed in the plumbago crucible, at 1.1～10atmN 2Under the pressure, 1500～1900 ℃ of synthetic 1～2h are then at Al 2O 3Coil decarburization 1～3h in interior 700 ℃ of air.To take off compound material behind the C and pack into and scribble in the graphite jig of BN, in 1700～1900 ℃, 30MPa, N 2Hot pressing 0.5～2h under the atmosphere can obtain relative density greater than 99% matrix material.
The used raw material of the present invention is Si 3N 4, SiO 2And carbon black, when at high temperature synthesizing the SiC whisker for assurance, Si 3N 4The unlikely decomposition of matrix needs to adopt N 2Protect, but because N 2Participation, Si 3N 4, SiO 2C and N 2Between at high temperature (1600 ℃) down very complicated chemical reaction may take place, sum up and get up to mainly contain following three reactions:
△G 0 1＝137500+3TlgT-92.44T Cal
△G 0 2＝98500-75.21T Cal
△G 0 3＝314000+9TlgT-202.11T Cal
As calculated, above-mentioned three standard free energies variations that are reflected under 1600 ℃ are respectively:
△G 0 1＝-17251Cal
△G 0 2＝-42368Cal
△G 0 3＝-9309Cal
This shows, consider that from the thermodynamics angle above-mentioned three reactions all may take place.Work as N 2Preponderated than the reaction of (1) (2) when pressure was 1atm, promptly as the Si of matrix material 3N 4To be transformed into SiC(with C reaction but not be the whisker shape), make SiC content be higher than expectation quantity; Like this, be the generation of inhibited reaction (2), should increase N 2Pressure, but the meeting of the trend of reaction (3) so increase, i.e. SiO 2Be transformed into Si 2N 4, be difficult to obtain estimating the SiC whisker of quantity.So,, guarantee SiO for the generation of inhibited reaction (2), (3) 2All generate the SiC that estimates quantity, must select suitable pressure range with the C reaction.Be defined as 1.1～10atm through experiment.
Consider Si simultaneously 3N 4If the phase composite of raw material is N 2Pressure excessive (＞3atm), then can promote α → β → Si 3N 4Phase transformation, make α-Si 3N 4Content reduces, β-Si 3N 4Content increases.
In 1500～1900 ℃ of scopes, when temperature during less than 1600 ℃, SiO 2Though the reaction of+3C → SiC+2CO can take place, react abundant inadequately, and particulate state SiC is more; After 1650 ℃, react completely, but the whisker surface deterioration.
In sum, synthetic Si 3N 4-SiC (w)The optimal processing parameter of compound material is: 1600～1650 ℃, and 2～2.5atmN 2Pressure.
Employed sintering aid is among the present invention: Y 2O 3, Al 2O 3And La 2O 3
After the synthetic SiC whisker,, therefore have remaining C and exist, also need in air 600～700 ℃ of decarburization 1～3h because C is excessive.And then will take off compound material after the C and pack into and scribble in the graphite jig of BN, in 1700～1900 ℃, 30MPa, N 2Protection (1atm) is hot pressing 0.5～2h down, can obtain fine and close matrix material.
Introduce embodiments of the invention below in conjunction with effect.
Embodiment 1, raw material: 62wt%Si 3N 4(mean particle size is 0.25 μ m, α-Si 3N 4Account for 94%, β-Si 3N 4Be that 5.2% free Si and other impurity are 0.8%), 18.18wt%SiO 2(granularity＜100 μ m), 16.1wt% carbon ink, sintering aid Y 2O 3And Al 2O 3Respectively be 1.86%.
Above-mentioned raw materials ball milling in anhydrous ethanol medium is mixed, sieves after the oven dry, in the plumbago crucible of packing in 1600 ℃, 2.5tmN 2Synthetic 2 h under the pressure, 700 ℃ of decarburization 2h in air atmosphere again take off compound material behind the C and carry out X-ray diffraction analysis and prove by α-Si 3N 4, β-Si 3N 4And β-SiC composition, under scanning electron microscope, can observe tangible whisker, diameter is 0.1～0.5 μ m, length is tens μ m.SiC content adopts infrared absorption determining C constituent content to convert out in the compound material.With the synthetic compound material at 1800 ℃, 1atmN 2Hot pressing 1h under the atmosphere.
Embodiment 2: proportioning raw materials is 69.44wt%Si 3N 4, 13.2wt%SiO 2, 13.20wt% carbon black, Y 2O 3And AL 2O 3Respectively be 2.08%.Manufacture method is with embodiment 1.
Embodiment 3: proportioning raw materials is with embodiment 1, in 1600 ℃, and 2atmN 2Following Synthetic 2 h, 700 ℃ are taken off C2h, and 1800 ℃, 1atmN 2Following hot pressing 1h.
Comparative Examples is Si same as the previously described embodiments 3N 4Raw material is in 1800 ℃, 1atmN 2Following hot pressing 1h.
The measurement of material mechanical performance: the normal temperature bending strength adopts three-point bending method, and specimen size is 3 * 4 * 36mm, and span is 30mm, and loading velocity is 0.5mm/min; Fracture toughness property adopts the coped beam method, and specimen size is 2 * 4 * 22mm, and kerf width is 84 μ m; High-temperature bending strength is 1300 ℃ of oxidation 100h, 1300 ℃ of intensity that record.
The measuring result such as the table 1 of the present invention and Comparative Examples show.
As can be seen from Table 1, because the existence of SiC whisker, the fracture toughness property of material has obtained very big improvement, by 5.7MPam 1/2Bring up to 8.0MPam 1/2, improved approximately 40% than matrix, simultaneously, the high-temperature behavior of material has had significant raising: Si 3N 4The hot strength of material is that 383MPa(is without 1300 ℃ * 100h oxidation), compare with normal temperature strength (750MPa) and to have reduced by 48.9%; And the hot strength of matrix material of the present invention is that 621MPa(is through 1300 ℃ * 100h oxidation), (670MP) compares with normal temperature strength, only reduced about 7.3%.
Compared with the prior art, the present invention directly adopts Si 3N 4Be matrix, use SiO simultaneously 2With the synthetic SiC whisker of carbon black, because the temperature higher (greater than 1550 ℃) that synthetic SiC whisker needs, all selecting the material that can not react with it and change in the prior art for use is matrix, as AL 2O 3Deng, and the present invention calculates and analyzes by thermodynamic argument, by selecting suitable atmosphere, pressure and synthesis temperature, has solved this difficult problem dexterously, has both guaranteed Si 3N 4Matrix can not change because of reaction takes place to decompose, and can obtain being uniformly distributed in the SiC whisker of the expectation quantity in the matrix again.The Si that the present invention obtains 3N 4-SiC (w)Method for composite material, with J63-64969,64970,64971 all methods are compared, have advantages such as technology is simple, easy to implement, the source of the gas requirement is single, can eliminate the harm that obnoxious flavour causes in composite material manufacturing process, and can obtain having the matrix material of excellent high-temperature behavior.
Table 1
1300℃×100h
Krc(MPa) after the oxidation
SiCvol%????δ（MPa）
·m 1/2） δ b1300℃
（MPa）
Si 3N 40 750 5.7 383°
Embodiment 1 15 670 8.0 621
Embodiment 2 10 640 7.0-
Embodiment 3 19 622 6.5-
* without 1300 ℃ * 100h oxidation.

Claims (2)

1, a kind of manufacture method of crystal whisker excess weld metal helium silicon composite, this method comprises: synthetic through 1～2 hour high temperature after required raw material is mixed, in 600～700 ℃ of insulations decarburization in 1～3 hour,, can obtain fine and close Si then again in 1700～1900 ℃ of following hot pressing 0.5～2 hour 3N 4-SiC (w)Matrix material is characterized in that: the content of raw material is (wt%): Si 3N 450～70, SiO 215～25, carbon black 10～20, sintering aid 3～8, described sintering aid are Y 2O 3, Al 2O 3And La 2O 3, under 1500～1900 ℃, 1.1～2.5atmN 2Synthetic compound material under the pressure.
2, manufacture method according to claim 1 is characterized in that: the optimal processing parameter of described synthetic compound material is 1600～1650 ℃, 2～2.5atmN 2Pressure.
CN 91100598 1991-02-04 1991-02-04 Making method of crystal whisker excess weld metal silicon nitride compound material Expired - Fee Related CN1026482C (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100381398C (en) * 2005-07-29 2008-04-16 南京理工大学 Preparation method of AlN Si3N4-SiC ceramic material

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1055324C (en) * 1994-06-30 2000-08-09 中国科学院金属研究所 Amorphous in-situ synthesized nm silicon nitride crystal whisker
CN1057515C (en) * 1997-10-24 2000-10-18 清华大学 Method for deoxidisation and reinforcement of solid organic procursor of silicon nitride material
CN1112337C (en) * 1999-05-28 2003-06-25 清华大学 Preparation of silicon nitride-based composite material with superhigh tenacity
CN109320276B (en) * 2018-10-15 2021-04-02 西北工业大学 Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transmitting ceramic
CN112159236B (en) * 2020-10-19 2021-06-11 江苏贝色新材料有限公司 High-thermal-conductivity silicon nitride ceramic substrate and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100381398C (en) * 2005-07-29 2008-04-16 南京理工大学 Preparation method of AlN Si3N4-SiC ceramic material

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