CN114591089A - Defect regulation and control-based ultrahigh-temperature ceramic densification method and ultrahigh-temperature ceramic - Google Patents
Defect regulation and control-based ultrahigh-temperature ceramic densification method and ultrahigh-temperature ceramic Download PDFInfo
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- 238000003786 synthesis reaction Methods 0.000 description 2
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- 150000003623 transition metal compounds Chemical class 0.000 description 2
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Abstract
The invention provides a defect regulation based densification method of ultrahigh-temperature ceramic, which comprises the following steps: preparing ultrahigh-temperature ceramic powder corresponding to each synthesis method by adopting a plurality of synthesis methods; calculating to obtain the dislocation density of the ultrahigh-temperature ceramic powder; determining the mixing proportion of the ultrahigh-temperature ceramic powder respectively obtained by various synthesis methods based on the calculated dislocation density of the powder; mixing the ultrahigh-temperature ceramics respectively obtained by the multiple synthesis methods according to the mixing proportion so as to regulate and control the defect concentration of the ultrahigh-temperature ceramic powder; sintering the mixed ultrahigh-temperature ceramic powder to obtain ultrahigh-temperature ceramic; the ultrahigh-temperature ceramic with high density is prepared by calculating the dislocation density and regulating and controlling the powder defects by using powder with different dislocation densities.
Description
Technical Field
The invention relates to the field of preparation of ultrahigh-temperature ceramics, in particular to a defect regulation-based ultrahigh-temperature ceramic densification method and ultrahigh-temperature ceramics.
Background
ultra-high-Temperature ceramic materials (UHTCs) mainly refer to a special material capable of maintaining chemical stability in a high-Temperature environment (above 2000 ℃) and a reaction atmosphere (such as an atomic oxygen environment), and generally include some high-melting-point transition metal compounds including borides, carbides and oxides. Among these high melting point transition metal compounds, TaC and ZrB2、HfB2HfC, etc. have melting points in excess of 3000 c, making them of great potential for use in extremely high temperature conditions. However, the high melting point of the ultra-high temperature ceramic also brings the problems of strong covalent bond and low self-diffusion rate, so that the ultra-high temperature ceramic is difficult to densify, which is a main difficulty which hinders the engineering application of the ultra-high temperature ceramic material at present.
The preparation of the ultra-high temperature ceramic material mainly comprises two parts of powder synthesis and powder sintering, and the synthesis of common ultra-high temperature ceramic powder generally adopts a self-propagating method, a sol-gel method and a carbothermic method. In the self-propagating method, due to the extremely high temperature rise/fall rate of the reaction, the reaction environment has high temperature gradient, so that the grown crystals deflect or bend to cause phase difference between adjacent crystal blocks and the thermal stress of rapid cooling volume change to form a large amount of dislocation, further, the powder has high defect concentration and high powder sintering activity, but the self-propagating reaction rate is too fast, the reaction is not thorough, the particle size of a product is large, the cost of raw materials is high, and the method is not beneficial to industrial production. The sol-gel method and the carbothermic method have slow reaction temperature rise/fall rate, sufficient grain nucleation and growth time, low dislocation density in the synthesized ultra-high temperature ceramic powder, low defect concentration and low powder sintering activity, and the high-densification ceramic is difficult to obtain by the conventional sintering method. Therefore, the improvement of the sintering activity of the ultrahigh-temperature ceramic powder and the realization of high densification are technical problems which need to be solved urgently in the promotion of engineering of the ultrahigh-temperature ceramic material.
Disclosure of Invention
In order to solve the problems, the invention provides an ultrahigh-temperature ceramic densification method based on defect regulation and control and ultrahigh-temperature ceramic. The specific contents are as follows:
in a first aspect, the invention provides a method for densification of ultrahigh-temperature ceramic based on defect regulation, which comprises the following steps:
preparing ultrahigh-temperature ceramic powder corresponding to each synthesis method by adopting a plurality of synthesis methods;
calculating the dislocation density of the ultrahigh-temperature ceramic powder obtained by the various synthesis methods;
determining the mixing proportion of the ultra-high temperature ceramic powder respectively obtained by multiple synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic powder;
mixing the ultrahigh-temperature ceramic powder obtained by the various synthesis methods according to the mixing proportion to regulate and control the defect concentration of the ultrahigh-temperature ceramic powder; wherein the dislocation density of the mixed ultrahigh-temperature ceramic powder is 1015m-2And the above;
and sintering the mixed ultrahigh-temperature ceramic powder to obtain the ultrahigh-temperature ceramic.
Preferably, the step of determining the mixing proportion of the ultra-high temperature ceramic powder respectively obtained by a plurality of synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic powder comprises the following steps:
determining the dislocation density of the ultrahigh-temperature ceramic powder to 1015m-2And the corresponding high dislocation density ultrahigh temperature ceramic powder, and the dislocation density is 1015m-2The following low dislocation density ultra-high temperature ceramic powder;
and determining the mixing proportion of the ultrahigh-temperature ceramic powder respectively obtained by a plurality of synthesis methods on the basis of 0.5-75% of the mass fraction of the ultrahigh-temperature ceramic powder with high dislocation density in the mixed powder.
Preferably, the mass fraction of the high dislocation density ultrahigh temperature ceramic powder in the mixed powder is 0.5-50%.
Preferably, the plurality of synthetic methods include a self-propagating method, a sol-gel method, a carbothermic method.
Preferably, the method for calculating the dislocation density is a method adopting X-ray diffraction combined with multiple convolution contour fitting;
specifically, the method for calculating the dislocation density comprises the following steps:
data such as diffraction curves and lattice parameters of the powder are obtained through X-ray diffraction, and dislocation density can be obtained through fitting of formulas (1-3) on the basis of convolution and superposition of different physical effect functions.
IM(2θ)＝∑hkl(Is*ID*IINST)+IBG (1)
In the formula: I.C. AM-a function of a diffraction profile; i isD-a grain strain function; i isS-a grain distribution function; i isINST-an instrument profile function; i isBG-a background function.
In the formula: erfc — complementary function of error; m and σ -the median and variance of the lognormal distribution function; Δ K ═ 2cos θ Δ θ/λ.
In the formula: ρ — dislocation density; b-Boehringer vector; c-contrast factor; g-diffraction vector, | g | ═2sin theta/lambda; f (η) -stress function, η ═ L/Re(ii) a L is a Fourier variable; re-effective outer cutoff radius of dislocations.
Preferably, the sintering method comprises: one of a pressureless sintering method, a hot-pressing sintering method, a hot isostatic pressing sintering method, and a spark plasma sintering method.
Preferably, the densification process is also applicable to sintering of rare earth boride powders, including: LaB6、YB6、GdB6、CeB6、YbB6、EuB6And the like.
In a second aspect, the invention provides an ultrahigh-temperature ceramic prepared by the defect-regulation-based ultrahigh-temperature ceramic densification method of the first aspect.
Compared with the prior art, the invention has the following advantages:
the embodiment of the invention provides a densification method of ultra-high temperature ceramic, which adopts various synthesis methods to prepare corresponding ultra-high temperature ceramic powder; calculating the dislocation density of the ultrahigh-temperature ceramic powder; determining the mixing proportion of the ultra-high temperature ceramics respectively obtained by a plurality of synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic; mixing the ultrahigh-temperature ceramics respectively obtained by the multiple synthesis methods according to the mixing proportion so as to regulate and control the defect concentration of the ultrahigh-temperature ceramic powder; wherein the dislocation density of the mixed ultrahigh-temperature ceramic powder is 1015m-2And the above; and sintering the mixed ultrahigh-temperature ceramic powder to obtain the ultrahigh-temperature ceramic.
In the embodiment of the invention, the dislocation density of the ultrahigh-temperature ceramic powder obtained by different synthesis methods is calculated, the ultrahigh-temperature ceramic powder with high dislocation density and low dislocation density is mixed based on the calculation result, the ultrahigh-temperature ceramic powder with high defect concentration is obtained, and the ultrahigh-temperature ceramic with the density of more than 95% can be obtained after sintering. According to the invention, the ultrahigh-temperature ceramic powder synthesized by the self-propagating method is mixed with the ultrahigh-temperature ceramic powder prepared by the carbothermic method and the sol-gel method according to a certain proportion, so that the problems of poor sintering performance, high raw material cost, inconvenience for industrial production and the like of single powder are solved, and on the other hand, by adopting the method for mixing the high-dislocation-density and low-dislocation-density powder, the ultrahigh-temperature ceramic with higher density can be obtained without adding extra sintering aids in the sintering process, so that the sintering process is simplified.
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Fig. 1 shows a flow chart of a densification method of ultra-high temperature ceramics in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and detailed description so that the above objects, features and advantages of the present invention can be more clearly understood. The following examples are given for the detailed implementation and the specific operation procedures, but the scope of the present invention is not limited to the following examples. The specific experimental procedures or conditions not specified in the examples can be performed according to the procedures or conditions of the conventional experimental procedures described in the prior art in this field. The reagents and other instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The applicant of the invention finds that the existing ultrahigh-temperature ceramic has the problems of low sintering activity of synthetic powder and difficult densification.
In order to solve the above problems, in a first aspect, the present invention provides a method for densification of ultra-high temperature ceramics based on defect regulation, the method comprising:
preparing ultrahigh-temperature ceramic powder corresponding to each synthesis method by adopting a plurality of synthesis methods;
calculating the dislocation density of the ultrahigh-temperature ceramic powder obtained by the multiple synthesis methods;
determining the mixing proportion of the ultra-high temperature ceramic powder respectively obtained by a plurality of synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic powder;
mixing the ultrahigh-temperature ceramic powder obtained by the various synthesis methods respectively according to the mixing proportion to regulate and control the ultrahigh temperatureDefect concentration of the warm ceramic powder; wherein the dislocation density of the mixed ultrahigh-temperature ceramic powder is 1015m-2And the above;
and sintering the mixed ultrahigh-temperature ceramic powder to obtain the ultrahigh-temperature ceramic.
In the embodiment of the invention, the determined proportion of the ultrahigh-temperature ceramic powder is the ratio of the mass fractions of the high-dislocation density powder and the low-dislocation density powder;
in the embodiment of the present invention, the plurality of synthesis methods may include a high temperature self-propagating method, a carbothermic method, a sol-gel method, a hydrothermal/solvothermal method, a plasma synthesis method, a precursor synthesis method, and the like; the sintering method of the ultrahigh-temperature ceramic powder body can comprise the following steps: hot pressing sintering, isostatic pressing sintering, hot isostatic pressing sintering, air pressure sintering, microwave sintering, spark plasma sintering and the like.
In general, a large number of dislocations are present in the powder, and the amount of these dislocations is expressed in terms of dislocation density, which is defined as the total length of dislocation lines contained in a unit volume of crystal; another definition of dislocation density is: the number of dislocation lines per unit cross-sectional area is also 1/cm. Generally, when the powder has a higher dislocation density, the powder can have higher lattice distortion energy, that is, the powder has higher activity, so that the densified ultrahigh-temperature ceramic can be obtained through sintering.
According to the embodiment of the invention, the low dislocation density and high dislocation density powder are combined, so that the dislocation density of the mixed powder is greatly improved compared with that of the low dislocation density powder, and the problem of high difficulty in obtaining the high dislocation density powder is solved.
Preferably, the step of determining the mixing proportion of the ultra-high temperature ceramics respectively obtained by a plurality of synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic comprises the following steps:
determining the dislocation density of the ultrahigh-temperature ceramic powder to 1015m-2And the corresponding high dislocation density ultrahigh temperature ceramic powder, and the dislocation density is 1015m-2The following low dislocation density ultra-high temperature ceramic powder;
the main factors influencing the sintering activity of the powder are the specific surface area of the powder, the granularity distribution, the shape and the purity of powder particles and the like, and the dislocation density 10 is prepared15m-2The powder increases the defect concentration of the powder, improves the sintering activity of the powder, and can obtain the ultrahigh-temperature ceramic with high density.
In the embodiment of the invention, according to the calculation result, the ultrahigh-temperature ceramic powder with high dislocation density is synthesized by a self-propagating method, the ultrahigh-temperature ceramic powder with low dislocation density is prepared by a carbothermic method and a sol-gel method, and the ultrahigh-temperature ceramic powder synthesized by the self-propagating method is combined with the ultrahigh-temperature ceramic powder synthesized by the carbothermic method and the sol-gel method, so that the problems of high cost and high raw material toxicity of a single self-propagating method can be solved, and the problems of low sintering activity of the powder and low density of the sintered ceramic caused by the single carbothermic method and the sol-gel method can be avoided.
And determining the mixing proportion of the ultrahigh-temperature ceramic powder respectively obtained by a plurality of synthesis methods on the basis of 0.5-75% of the mass fraction of the ultrahigh-temperature ceramic powder with high dislocation density in the mixed powder.
Preferably, the mass fraction of the high dislocation density ultrahigh temperature ceramic powder in the mixed powder is 0.5-50%.
In the embodiment of the invention, if the mass fraction of the ultrahigh-temperature ceramic powder with high dislocation density is too low, the defect concentration of the mixed powder is low, and the powder with good sintering activity is difficult to obtain; when the mass fraction of the ultrahigh-temperature ceramic powder with high dislocation density is too high, the problems of high production cost, low raw material utilization rate and the like of the ultrahigh-temperature ceramic can be faced.
Preferably, the plurality of synthetic methods include a self-propagating method, a sol-gel method, a carbothermic method.
Preferably, the method for calculating the dislocation density is a method adopting X-ray diffraction combined with multiple convolution contour fitting;
specifically, the method for calculating the dislocation density comprises the following steps:
data such as diffraction curves and lattice parameters of the powder are obtained through X-ray diffraction, and dislocation density can be obtained through fitting of formulas (1-3) on the basis of convolution and superposition of different physical effect functions.
IM(2θ)＝∑hkl(Is*ID*IINST)+IBG (1)
In the formula: I.C. AM-a function of a diffraction curve; i isD-a grain strain function; i isS-a grain distribution function; i isINST-an instrument profile function; i isBG-a background function.
In the formula: erfc — complementary function of error; m and σ -the median and variance of the lognormal distribution function; Δ K ═ 2cos θ Δ θ/λ.
In the formula: ρ — dislocation density; b-Boehringer vector; c-a contrast factor; g-diffraction vector, | g | ═ 2sin θ/λ; f (η) -stress function, η ═ L/Re(ii) a L is a Fourier variable; re-effective outer cutoff radius of dislocations.
Preferably, the sintering method comprises: one of a pressureless sintering method, a hot-pressing sintering method, a hot isostatic pressing sintering method, and a spark plasma sintering method.
Preferably, the densification process is also applicable to sintering of rare earth boride powders, including: LaB6、YB6、GdB6、CeB6、YbB6、EuB6And the like.
In a second aspect, the present application provides an ultra-high temperature ceramic prepared by the defect-control-based ultra-high temperature ceramic densification method of the first aspect.
In order that those skilled in the art will better understand the present invention, one of the present inventions is described below in terms of several specific embodiments.
Example 1:
ZrB preparation by adopting self-propagating method and carbothermic method2Powder;
respectively carrying out X-ray diffraction on the powder obtained by the self-propagating method and the powder obtained by the carbothermic method to obtain basic data such as a diffraction curve, lattice parameters and the like, calculating the dislocation density of the two powders by utilizing a CMWP-fit method, and calculating to obtain ZrB prepared by the self-propagating method2The dislocation density of the powder is 8.68 multiplied by 1015m-2ZrB prepared by carbothermic method2Dislocation density of powder is 6.49 × 1011m-2；
Mixing the two powders, wherein ZrB is prepared by a self-propagating method2The proportion of the powder is 25 percent, and the dislocation density of the powder after calculation and regulation is 2.67 multiplied by 1015m-2(ii) a Densifying the regulated powder by adopting a hot-pressing sintering method to obtain ZrB2A ceramic.
According to the calculation result, the calculated ZrB2Dislocation density of powder, compared with ZrB prepared by single carbothermic method2Greatly increasing dislocation density of powder, increasing defect concentration, and measuring ZrB obtained by sintering2The density of the ceramic is 96%, and compared with the ultrahigh-temperature ceramic powder obtained by a single carbothermic synthesis method, the density of the sintered ceramic is greatly improved.
Example 2:
ZrB preparation by adopting self-propagating method and sol-gel method2Powder;
respectively carrying out X-ray diffraction on the powder obtained by the self-propagating method and the powder obtained by the sol-gel method to obtain basic data such as a diffraction curve, lattice parameters and the like, calculating the dislocation density of the two kinds of powder by utilizing a CMWP-fit method, and obtaining ZrB prepared by the self-propagating method2The dislocation density of the powder is 8.68 multiplied by 1015m-2ZrB prepared by carbothermic method2Dislocation density of powder is 6.49 × 1011m-2；
Mixing the two powders, wherein ZrB is prepared by a self-propagating method2The powder proportion is 50 percent, and the powder is calculated and regulatedDislocation density of powder is 5.41 × 1015m-2Densifying the regulated powder by a pressureless sintering method to obtain ZrB2And (3) ceramic.
According to the calculation result, the calculated ZrB2Dislocation density of powder, compared with ZrB prepared by single sol-gel method2The dislocation density of the powder is greatly improved, the defect concentration is increased, and ZrB obtained by sintering is measured2The ceramic density is 97%, compared with the ultrahigh-temperature ceramic powder obtained by a single sol-gel method, the ceramic density obtained by sintering is greatly improved.
Example 3:
ZrB preparation by adopting self-propagating method and carbothermic method2Powder;
respectively obtaining the basic data such as diffraction curve and lattice parameter by X-ray diffraction of the powder obtained by the self-propagating method and the powder obtained by the carbothermic method, calculating the dislocation density of the two powders by using a CMWP-fit method, and obtaining ZrB prepared by the self-propagating method2The dislocation density of the powder is 8.68 multiplied by 1015m-2ZrB prepared by carbothermic method2Dislocation density of powder is 6.49 × 1011m-2；
Mixing the two powders, wherein ZrB is prepared by a self-propagating method2The proportion of the powder is 75 percent, and the dislocation density of the powder after calculation and regulation is 7.90 multiplied by 1015m-2Densifying the regulated powder by adopting a hot isostatic pressing sintering method to obtain ZrB2A ceramic.
According to the calculation result, the calculated ZrB2Dislocation density of powder, compared with ZrB prepared by single carbothermic method2The dislocation density of the powder is greatly improved, the defect concentration is increased, and ZrB obtained by sintering is measured2The density of the ceramic is 98.3%, and compared with the ultrahigh-temperature ceramic powder obtained by a single carbothermic synthesis method, the density of the ceramic obtained by sintering is greatly improved.
Example 4:
preparation of HfB by self-propagating method and carbothermic method2Powder;
mixing the powder obtained by self-propagating method with the powder obtained by carbothermic methodObtaining basic data such as diffraction curve and lattice parameter by X-ray diffraction, calculating dislocation density of two kinds of powder by CMWP-fit method, and obtaining HfB prepared by self-propagating method2Dislocation density of powder is 7.81X 1015m-2HfB prepared by carbothermic process2Dislocation density of powder is 5.66X 1011m-2；
Mixing the two powders, wherein HfB is self-propagating2The proportion of the powder is 75 percent, and the dislocation density of the powder after calculation and regulation is 6.13 multiplied by 1015m-2The regulated and controlled powder is densified by adopting a hot-pressing sintering method to obtain HfB2And (3) ceramic.
From the calculation results, the calculated HfB was found2Powder dislocation density, compared with HfB prepared by single carbothermic method2The dislocation density of the powder is greatly improved, the defect concentration is increased, and HfB obtained by sintering is measured2The density of the ceramic is 98%, compared with the ultrahigh-temperature ceramic powder obtained by a single carbothermic reduction synthesis method, the density of the ceramic obtained by sintering is greatly improved.
Example 5:
respectively adopting self-propagating method and carbothermic method to prepare TiB2Powder;
respectively obtaining the powder obtained by the self-propagating method and the powder obtained by the carbothermic method through X-ray diffraction to obtain the basic data such as diffraction curve, lattice parameter and the like, calculating the dislocation density of the two powders by utilizing a CMWP-fit method, and obtaining the TiB prepared by the self-propagating method2Dislocation density of powder is 5.67X 1015m-2TiB prepared by carbothermic process2Dislocation density of powder is 4.35 × 1011m-2；
Mixing the two powders, wherein TiB is self-propagating method2The proportion of the powder is 25 percent, and the dislocation density of the powder after calculation and regulation is 5.76 multiplied by 1014m-2Densifying the regulated powder by a hot-pressing sintering method to obtain TiB2A ceramic.
According to the calculation result, the calculated TiB2Dislocation density of powder, compared with TiB prepared by single carbothermic method2Powder positionThe dislocation density is greatly improved, the defect concentration is increased, and the TiB obtained by sintering is measured2The density of the ceramic is 97%, compared with the ultrahigh-temperature ceramic powder obtained by a single carbothermic reduction synthesis method, the density of the ceramic obtained by sintering is greatly improved.
Example 6
ZrB preparation by adopting self-propagating method and carbothermic method2Powder;
respectively carrying out X-ray diffraction on the powder obtained by the self-propagating method and the powder obtained by the carbothermic method to obtain basic data such as a diffraction curve, lattice parameters and the like, calculating the dislocation density of the two powders by utilizing a CMWP-fit method, and calculating to obtain ZrB prepared by the self-propagating method2The dislocation density of the powder is 8.68 multiplied by 1015m-2ZrB prepared by carbothermic method2Dislocation density of powder is 6.49 × 1011m-2；
Mixing the two powders, wherein ZrB is prepared by a self-propagating method2The proportion of the powder is 0.5 percent, and the dislocation density of the powder after calculation and regulation is 1.05 multiplied by 1015m-2(ii) a Densifying the regulated powder by adopting a hot-pressing sintering method to obtain ZrB2A ceramic.
According to the calculation result, the calculated ZrB2Dislocation density of powder, compared with ZrB prepared by single carbothermic method2Greatly improving the dislocation density of the powder, increasing the defect concentration, and measuring ZrB obtained by sintering2The density of the ceramic is 95%, and compared with the ultrahigh-temperature ceramic powder obtained by a single carbothermic synthesis method, the density of the sintered ceramic is greatly improved.
According to the embodiment results, the density of the ultrahigh-temperature ceramic obtained by mixing and sintering the high-dislocation-density powder and the low-dislocation-density powder is over 95%, so that the problems of low sintering activity and difficulty in densification caused by a single synthesis method are solved, the cost of synthesizing the powder is reduced, the sintering process flow is simplified, and the method is beneficial to industrial production.
For simplicity of explanation, the method embodiments are described as a series of acts or combinations, but those skilled in the art will appreciate that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are preferred embodiments and that the acts and elements referred to are not necessarily required to practice the invention.
The method for densifying the ultrahigh-temperature ceramic based on defect regulation and control and the ultrahigh-temperature ceramic provided by the invention are described in detail, specific examples are applied in the method for explaining the principle and the implementation mode of the invention, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (7)
1. A method for densifying ultrahigh-temperature ceramic based on defect regulation is characterized by comprising the following steps:
preparing ultrahigh-temperature ceramic powder corresponding to each synthesis method by adopting a plurality of synthesis methods;
calculating the dislocation density of the ultrahigh-temperature ceramic powder obtained by the multiple synthesis methods;
determining the mixing proportion of the ultra-high temperature ceramic powder respectively obtained by multiple synthesis methods based on the calculated dislocation density of each ultra-high temperature ceramic powder;
mixing the ultrahigh-temperature ceramic powder obtained by the various synthesis methods according to the mixing proportion to regulate and control the defect concentration of the ultrahigh-temperature ceramic powder; wherein the dislocation density of the mixed ultrahigh-temperature ceramic powder is 1015m-2And the above;
and sintering the mixed ultrahigh-temperature ceramic powder to obtain the ultrahigh-temperature ceramic.
2. The method for densifying ultrahigh-temperature ceramic based on defect regulation and control of claim 1, wherein the step of determining the mixing proportion of the ultrahigh-temperature ceramic powder respectively obtained by a plurality of synthesis methods based on the calculated dislocation density of each ultrahigh-temperature ceramic powder comprises the steps of:
determining the dislocation density of the ultrahigh-temperature ceramic powder to 1015m-2And the corresponding high dislocation density ultrahigh temperature ceramic powder, and the dislocation density is 1015m-2The following low dislocation density ultra-high temperature ceramic powder;
and determining the mixing proportion of the ultrahigh-temperature ceramic powder respectively obtained by a plurality of synthesis methods on the basis of 0.5-75% of the mass fraction of the high-dislocation density ultrahigh-temperature ceramic powder in the mixed powder.
3. The densification method of the ultrahigh-temperature ceramic based on defect regulation and control of claim 2, characterized in that the mass fraction of the high-dislocation density ultrahigh-temperature ceramic powder in the mixed powder is 0.5% -50%.
4. The densification method of ultrahigh-temperature ceramic based on defect regulation according to claim 1, characterized in that the multiple synthesis methods comprise a self-propagating method, a sol-gel method and a carbothermal reduction method.
5. The densification method of ultrahigh-temperature ceramic based on defect regulation according to claim 1, characterized in that the method for calculating dislocation density is a method using X-ray diffraction combined with multiple convolution profile fitting.
6. The densification method of ultrahigh-temperature ceramic based on defect regulation according to claim 1, characterized in that the sintering method comprises: one of a pressureless sintering method, a hot-pressing sintering method, a hot isostatic pressing sintering method, and a spark plasma sintering method.
7. An ultra-high temperature ceramic, characterized in that the ultra-high temperature ceramic is prepared by the defect regulation-based ultra-high temperature ceramic densification method of any one of claims 1 to 6.
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| CN101096272A (en) * | 2007-06-04 | 2008-01-02 | 哈尔滨工业大学 | Nitride silicon based composite material burning synthesis method |
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