CN107353012A - A kind of composite thermoelectric material and preparation method thereof - Google Patents
A kind of composite thermoelectric material and preparation method thereof Download PDFInfo
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- CN107353012A CN107353012A CN201610302274.5A CN201610302274A CN107353012A CN 107353012 A CN107353012 A CN 107353012A CN 201610302274 A CN201610302274 A CN 201610302274A CN 107353012 A CN107353012 A CN 107353012A
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Abstract
The present invention provides a kind of composite thermoelectric material, and the composite thermoelectric material includes SiC, Mg2Si and optional doped chemical Sb, wherein, SiC and Mg2Si volume ratio is 5:95‑40:60, and doped chemical Sb and Mg2Si mol ratio 0 0.03：1.The composite thermoelectric material of the present invention is a kind of potential high-temperature region thermoelectric material, and its consistency is high (for example, its density is the 95% or higher of solid density), hardness is big, not easy to break, in 825K, thermoelectric figure of merit ZT has potential application prospect up to 0.3.In addition, present invention also offers a kind of method for preparing the composite thermoelectric material, it has the advantages that, and preparation temperature is relatively low, technological parameter is easily controllable, short preparation period, product component are controllable.
Description
Technical field
The invention belongs to technical field of inorganic material, more particularly to a kind of composite thermoelectric material and its preparation
Method.
Background technology
Thermoelectric material can realize the mutual conversion between heat energy and electric energy, and conversion process is without machinery
Moving component, it is noiseless, without abrasion, its mechanism is simple, environmentally safe, it is considered to be solve
One of main path of energy crisis.Thermoelectric material can be divided into low-temperature space heat by the temperature range of its work
Electric material, middle warm area thermoelectric material and high-temperature region thermoelectric material.Because material easily occurs in high temperature
The problems such as oxidation and fusing, therefore high-temperature region thermoelectric material is relatively in short supply.
Mg2Si base semiconductor materials are a kind of high temperature thermoelectric materials, raw material Mg and Si used in it
All rich reserves and nontoxic environmentally friendly on earth.Pure Mg2The electric conductivity of Si thermoelectric materials is relatively low,
Thermoelectricity capability is poor.At present, Mg can be improved by Sb doping2The thermoelectricity capability of Si materials, but Sb
The Mg of doping2It is easily broken off after Si sills sintering, is unfavorable for synthesizing big quality bulk material, and high temperature
Bad mechanical property.
Carborundum (SiC) is one of wide bandgap semiconductor materials received significant attention, has breakdown
Field strength is high, carrier saturation drift velocity is big, heat endurance is good, good in oxidation resistance and good mechanical property
The advantages that, it is considered to be the high temperature semiconductors material of function admirable.In addition, the temperature difference of carborundum is electronic
Gesture rate (Seebeck coefficients) greatly, poorly conductive.At present, can be by adulterating the member such as N, Al usually
Improved electric conductivity is obtained, electrical conductivity can regulate and control in the range of several orders of magnitude, and thermal conductivity can pass through
Reduce material granule degree to reduce, thus it is potential high-temperature thermoelectric material again.
At present, the problem of SiC base thermoelectricity materials are present is mainly that required sintering temperature is high, hardly possible shaping.
For example, the sintering temperature of pure SiC thermoelectric materials is typically more than 2000 DEG C.For another example SiC-B4C
The sintering preparation temperature of composite thermoelectric material (J.Eur.Ceram.Soc.24,409 more than 1800 DEG C
(2004))。
Therefore, still suffer from that continual exploitation sinter molding temperature is low at present, be easy to the high warm of sinter molding
The demand of electric material.
The content of the invention
The present invention provides a kind of composite thermoelectric material and preparation method thereof.Compound thermoelectricity provided by the invention
Material is a kind of high-temperature thermoelectric material, and hardness is big, and its sinter molding temperature is low, is easy to sinter molding,
It is and not easy to break after sintering.
The purpose of the present invention is achieved through the following technical solutions.
On the one hand, the invention provides a kind of composite thermoelectric material, the composite thermoelectric material to include
SiC、Mg2Si and optional doped chemical Sb, wherein, SiC and Mg2Si volume ratio is
5:95-40:60, and doped chemical Sb and Mg2Si mol ratio 0-0.03：1.
In the present invention, the SiC and Mg2Si volume ratio be according to its solid density by raw material come
Metering.Further, since Sb doping enters Mg2In Si, its caused Volume Changes can be ignored
Disregard, therefore, SiC and Mg in the present invention2Si volume ratio and its volume fraction can be with cross-references.
According to composite thermoelectric material provided by the invention, wherein, the composite thermoelectric material is sintering
The form of dense body.
Present inventors have surprisingly discovered that composite thermoelectric material of the invention is in relatively low sintering temperature
Under, especially, with pure Mg2It under the same or analogous sintering temperatures of Si, can sinter into cause
Dense body.Further, the inventors discovered that, do not allow after composite thermoelectric material of the invention sintering easily broken
Split, be advantageous to synthesize the block materials of big quality.
In some embodiments, the density of the composite thermoelectric material for its solid density 95% or
It is higher；And in some embodiments, the density of the composite thermoelectric material is its solid density
97% or higher.
In the present invention, the solid density of composite thermoelectric material is obtained by following methods：By XRD
Determine SiC and Mg2Si cell parameter, and respective solid density is calculated, then by respective reason
Its volume fraction is multiplied by by density, so as to obtain the solid density of composite thermoelectric material.
According to composite thermoelectric material provided by the invention, wherein, SiC and Mg2Si volume ratio is
5:95-20:80, preferably 5:95-15:85.
According to composite thermoelectric material provided by the invention, can be improved by using doped chemical Sb compound
The thermoelectricity capability of thermoelectric material.In some preferred embodiments, Sb and Mg2Si mol ratio is
0.005-0.03：1, and in other preferred embodiments, Sb and Mg2Si mol ratio is
0.005-0.015：1.
According to composite thermoelectric material provided by the invention, wherein, the SiC is selected from 4H-SiC, 6H-SiC
With the one or more in 3C-SiC.
According to composite thermoelectric material provided by the invention, wherein, the SiC can be conductive or mix
Miscellaneous.In some preferred embodiments, the SiC is that n-type adulterates SiC, and preferably N mixes
Miscellaneous SiC.
On the other hand, the invention provides a kind of method for preparing described composite thermoelectric material, wherein,
Methods described includes：
(1) by SiC powder, Mg2Si powder and optional Sb powder carry out ball milling mixing, so as to
Mixed-powder is made；With
(2) mixed-powder made from plasma discharge sintering process sintering step (1) is utilized, so as to
Composite thermoelectric material is made.
According to method provided by the invention, wherein the SiC powder can be high-purity or conductive,
Crystal formation can be 4H, 6H, 3C-SiC or their mixture.
In the present invention, to SiC powder, Mg2Si powder and Sb particle diameter do not have particular/special requirement, as long as
Suitable for ball milling to realize their uniform mixing.However, it is believed that less particle diameter is advantageous to thermoelectricity
The uniform mixing of material, and advantageously reduce lattice thermal conductivity.
In some embodiments, the average grain diameter of SiC powder is in below 100nm, is preferably existed
Not higher than 60nm, for example, particle diameter is 40nm.In some specific embodiments, SiC powder is put down
Equal particle diameter is 40-100nm, and 40-60nm in some embodiments.
In other embodiments, Mg2Si powder average particle sizes are in below 100nm, preferably
Not higher than below 80nm, for example, particle diameter is 40nm.In some specific embodiments, Mg2Si
The average grain diameter of powder is 40-100nm, and 40-80nm in some embodiments.
According to method provided by the invention, wherein, the ball milling mixing described in step (1) exists
7500-10000 revs/min, for example, carrying out 3-5 hours under 8000 revs/min of rotating speed.
According to method provided by the invention, wherein, the ball milling mixing described in step (1) is with interval
The mode of ball milling is carried out.
According to method provided by the invention, wherein, Mg2Si powder can be made by solid reaction process
It is standby.In some preferred embodiments, Mg2Si powder is the method system by comprising the following steps
Standby：
(a) it is Mg by atomic ratio：Si=2.1-2.2:1, for example, Mg：Si=2.1:1, weigh magnesium and
Silicon raw material, it is placed in interval ball milling 3-5 hours in ball grinder；
(b) by the raw material tabletting after ball milling in step (a), and under an argon atmosphere in 500-550 DEG C,
For example, 5-10 hours are sintered at a temperature of 530 DEG C, so as to which Mg be made2Si。
According to method provided by the invention, wherein, interval ball milling described in step (a) is in 7500-10000
Rev/min, for example, being carried out under 8000 revs/min of rotating speed.
According to method provided by the invention, wherein, the pressure of argon gas is 0.2-0.3 in step (b)
Atmospheric pressure.
According to method provided by the invention, wherein, the plasma discharge described in step (2) burns
The condition of connection is as follows：For vacuum in below 0.1Pa, sample pressure is 60-70MPa；Preferably
65-70MPa；Sintering temperature is 700-900 DEG C, preferably 750-900 DEG C；It is 8-15 with sintering time
Minute.
Beneficial effects of the present invention comprise at least：
(1) present inventors have surprisingly discovered that, by Mg2Si is compound with SiC, with Mg2Si phases
Than not improving sinter molding temperature, considerably improving the hardness of composite thermoelectric material, sample is not
Easy fracture, and prepare Mg2Raw material Mg and Si used in Si all rich reserves, nontoxic on earth
It is environmentally friendly.
(2) Mg after sintering2Si/SiC composite thermoelectric materials are a kind of potential high-temperature region thermoelectricity materials
Material, its consistency is high (for example, its density is the 95% or higher of solid density), and hardness is big, machine
Tool performance is good, and in 825K, thermoelectric figure of merit ZT has potential application prospect up to 0.3.
(3) composite thermoelectric material of the invention can be sintered by plasma discharge sintering process and prepared；
By comparison, SiC thermoelectric materials and such as SiC-B4The SiC base thermoelectricity materials of C composite thermoelectric materials
Material is unsuitable for the preparation of using plasma discharge sintering method, and sintering temperature is high, hardly possible shaping.Present invention tool
Have the advantages that preparation temperature is relatively low, technological parameter is easily controllable, short preparation period, product component are controllable.
Brief description of the drawings
Hereinafter, embodiment of the present invention is described in detail with reference to accompanying drawing, wherein：
Fig. 1 shows the XRD spectra of the composite thermoelectric material of embodiments of the invention 1；
Fig. 2 shows the thermoelectric figure of merit ZT of the composite thermoelectric material of embodiments of the invention 1 with temperature
Change curve；
Fig. 3 shows the XRD spectra of the composite thermoelectric material of embodiments of the invention 2；
Fig. 4 shows the composite thermoelectric material thermoelectric figure of merit ZT of embodiments of the invention 2 with temperature
Change curve；
Fig. 5 shows the XRD spectra of the composite thermoelectric material of embodiments of the invention 3；
Fig. 6 shows the thermoelectric figure of merit ZT of the composite thermoelectric material of embodiments of the invention 3 with temperature
Change spectrogram；
Fig. 7 shows the XRD spectra of the composite thermoelectric material of embodiments of the invention 4；
Fig. 8 shows the thermoelectric figure of merit ZT of the composite thermoelectric material of embodiments of the invention 4 with temperature
Change spectrogram.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, below in conjunction with specific
Embodiment, the present invention is described in more detail.It should be appreciated that specific embodiment described herein
Only to explain the present invention, the scope being not intended to be limiting of the invention.
In following examples, unless specific instructions, used reagent is commercially available chemical reagent.
Embodiment 1
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=5:95 Mg2The compound thermoelectricity of Si/SiC
Material (that is, the SiC comprising 5vol% and 95vol% Mg2S Mg2The compound thermoelectricity materials of Si/SiC
Material) and preparation method thereof.
Specifically, Mg2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintered 8 hours at 530 DEG C,
So as to which Mg be made2Si。
(3) 0.0843g high-purity alpha-SiC powder is weighed in the glove box that Ar atmosphere is enclosed, and (crystal formation is
6H-SiC, average grain diameter 40nm) and Mg made from (2) the step of 1.0013g2Si powder,
Interval ball milling 3 hours in the ball grinder of steel are placed in, so as to which Mg be made2Si/SiC mixed-powders,
Wherein the rotating speed of ball grinder is 8000 revs/min.
(4) obtained Mg in the step of taking 0.7g (3)2Si/SiC mixed-powders, utilize plasma
Body discharge sintering method sinters, so as to which the block composite thermoelectric material containing 5vol%SiC be made；Wherein,
Sintering condition is：Sample pressure is 65MPa, and sintering temperature is 750 DEG C, and sintering time is 10 points
Clock, chamber pressure is in below 0.1Pa.
The Mg of embodiment 1 is measured by XRD2Si/SiC composite thermoelectric material samples, as a result such as Fig. 1
It is shown.It will be seen from figure 1 that the Mg containing 5vol%SiC after the sintering2The compound thermoelectricity of Si/SiC
SiC and Mg are only existed in material sample2Si diffraction maximum, this illustrates SiC and Mg in sample2Si is
Exist in the form of compound.
The density of the sample of embodiment 1 is measured, the results are shown in Table 1.Measurement the sample of embodiment 1 density be
The 98% of solid density, illustrate the Mg obtained by the inventive method2Si/SiC composite samples consistency is high.
Fig. 2 is the thermoelectric figure of merit ZT variation with temperature curves of the sample of embodiment 1.Can be with from Fig. 2
Find out, when test temperature is 725K, ZT values are 0.10.
The sample of embodiment 1 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 1
Hardness significantly improves.
Embodiment 2
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=10:90 Mg2The compound thermoelectricity of Si/SiC
Material (that is, the SiC comprising 10vol% and 90vol% Mg2S Mg2The compound thermoelectricity materials of Si/SiC
Material) and preparation method thereof.
Specifically, Mg2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintered 8 hours at 530 DEG C,
So as to which Mg be made2Si。
(3) 0.1249g high-purity alpha-SiC powder is weighed in the glove box that Ar atmosphere is enclosed, and (crystal formation is
6H-SiC, average grain diameter 40nm) and Mg made from (2) the step of 0.7025g2Si powder,
Interval ball milling 3 hours in the ball grinder of steel are placed in, so as to which Mg be made2Si/SiC mixed-powders,
Wherein the rotating speed of ball grinder is 8000 revs/min.
(4) obtained Mg in the step of taking 0.7g (3)2Si/SiC mixed-powders, utilize plasma
Body discharge sintering method sinters, so as to which the block composite thermoelectric material containing 10vol%SiC be made；Its
In, sintering condition is：Sample pressure is 65MPa, and sintering temperature is 800 DEG C, and sintering time is
10 minutes, chamber pressure was in below 0.1Pa.
The Mg of embodiment 2 is measured by XRD2Si/SiC composite thermoelectric material samples, as a result such as Fig. 3
It is shown.From figure 3, it can be seen that the Mg containing 10vol%SiC after the sintering2Si/SiC compound thermals
SiC and Mg are only existed in electric material sample2Si diffraction maximum, this illustrates SiC and Mg in sample2Si
It is to exist in the form of compound.
The density of the sample of embodiment 2 is measured, the results are shown in Table 1.Measurement the sample of embodiment 2 density be
The 98% of solid density, illustrate the Mg obtained by the inventive method2Si/SiC composite samples consistency is high.
Fig. 4 is the thermoelectric figure of merit ZT variation with temperature curves of the sample of embodiment 2.Can be with from Fig. 4
Find out, when test temperature is 725K, ZT values are 0.08.
The sample of embodiment 2 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 2
Hardness significantly improves.
Embodiment 3
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=15:85 Mg2The compound thermoelectricity of Si/SiC
Material (that is, the SiC comprising 15vol% and 85vol% Mg2S Mg2The compound thermoelectricity materials of Si/SiC
Material) and preparation method thereof.
Specifically, Mg2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintering 8 is small at 530 DEG C
When, so as to which Mg be made2Si。
(3) 0.1791g high-purity alpha-SiC powder is weighed in the glove box that Ar atmosphere is enclosed, and (crystal formation is
6H-SiC, average grain diameter 40nm) and Mg made from (2) the step of 0.6343g2Si powder,
Interval ball milling 3 hours in the ball grinder of steel are placed in, so as to which Mg be made2Si/SiC mixed-powders,
Wherein the rotating speed of ball grinder is 8000 revs/min.
(4) obtained Mg in the step of taking 0.7g (3)2Si/SiC mixed-powders, utilize plasma
Body discharge sintering method sinters, so as to which the block composite thermoelectric material containing 15vol%SiC be made；Its
In, sintering condition is：Sample pressure is 65MPa, and sintering temperature is 800 DEG C, and sintering time is
10 minutes, chamber pressure was in below 0.1Pa.
The Mg of embodiment 3 is measured by XRD2Si/SiC composite thermoelectric material samples, as a result such as Fig. 5
It is shown.From fig. 5, it can be seen that the Mg containing 15vol%SiC after the sintering2Si/SiC compound thermals
SiC and Mg are only existed in electric material sample2Si diffraction maximum, this illustrates SiC and Mg in sample2Si
It is to exist in the form of compound.
The density of the sample of embodiment 3 is measured, the results are shown in Table 1.Measurement the sample of embodiment 3 density be
The 98% of solid density, illustrate the Mg obtained by the inventive method2Si/SiC composite thermoelectric material samples
Consistency it is high.
Fig. 6 is the thermoelectric figure of merit ZT variation with temperature curves of the sample of embodiment 3.Can be with from Fig. 6
Find out, when test temperature is 725K, ZT values are 0.04.
The sample of embodiment 3 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 3
Hardness significantly improves.
Embodiment 4
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=15:The Mg of 85 Sb doping2Si/SiC
Composite thermoelectric material (that is, the SiC comprising 15vol% and 85vol% Mg2S Sb doping
Mg2Si/SiC composite thermoelectric materials) and preparation method thereof.
Specifically, the Mg of Sb doping2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintering 8 is small at 530 DEG C
When, so as to which Mg be made2Si。
(3) 0.1791g N doping SiC powder (current-carrying is weighed in the glove box that Ar atmosphere is enclosed
Sub- concentration 1018/cm3, crystal formation 6H-SiC, average grain diameter 40nm), 0.6343g the step of (2)
Obtained Mg2Si powder and 0.0152g Sb powder, are placed in interval ball milling 3 in the ball grinder of steel
Hour, so as to which the Mg containing Sb be made2The rotating speed of Si/SiC mixed-powders, wherein ball grinder is 8000
Rev/min.
(4) the obtained Mg containing Sb in the step of taking 0.7g (3)2Si/SiC mixed-powders,
Sintered using plasma discharge sintering process, so as to which the block doping of the Sb containing 15vol%SiC be made
Mg2Si/SiC composite thermoelectric materials；Wherein, sintering condition is：Sample pressure is 65MPa, is burnt
Junction temperature is 800 DEG C, and sintering time is 10 minutes, and chamber pressure is in below 0.1Pa.
The Mg of the Sb doping of embodiment 4 is measured by XRD2Si/SiC composite thermoelectric material samples,
As a result it is as shown in Figure 7.From figure 7 it can be seen that the doping of the Sb containing 15vol%SiC after the sintering
Mg2SiC and Mg are only existed in Si/SiC composite thermoelectric material samples2Si diffraction maximum, illustrates sample
SiC and Mg in product2Si is present in the form of compound.It is not intended to bound by theory, it is believed that Sb mixes
It is miscellaneous enter sample structure cell in, so as to be advantageous to improve material electric conductivity.
The density of the sample of embodiment 4 is measured, the results are shown in Table 1.Measurement the sample of embodiment 4 density be
The 98% of solid density, illustrate that the Sb obtained by the inventive method adulterates Mg2The compound thermoelectricity of Si/SiC
The consistency of material sample is high.
Fig. 8 is the thermoelectric figure of merit ZT variation with temperature curves of the sample of embodiment 4.Can be with from Fig. 8
To find out, when test temperature is 725K, ZT values are 0.23, when test temperature is 825K, ZT values
For 0.30.
The sample of embodiment 4 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 4
Hardness significantly improves.
Embodiment 5
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=20:80 Mg2The compound thermoelectricity of Si/SiC
Material (that is, the SiC comprising 20vol% and 80vol% Mg2S Mg2The compound thermoelectricity materials of Si/SiC
Material) and preparation method thereof.
Specifically, Mg2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintered 5 hours at 530 DEG C,
So as to which Mg be made2Si。
(3) 0.3373g high-purity alpha-SiC powder is weighed in the glove box that Ar atmosphere is enclosed, and (crystal formation is
6H-SiC, average grain diameter 40nm) and Mg made from (2) the step of 0.8432g2Si powder,
Interval ball milling 3 hours in the ball grinder of steel are placed in, so as to which Mg be made2Si/SiC mixed-powders,
Wherein the rotating speed of ball grinder is 8000 revs/min.
(4) obtained Mg in the step of taking 0.8g (3)2Si/SiC mixed-powders, utilize plasma
Body discharge sintering method sinters, so as to which the block composite thermoelectric material containing 20vol%SiC be made；Its
In, sintering condition is：Sample pressure is 70MPa, and sintering temperature is 850 DEG C, sintering time 8
Minute, chamber pressure is in below 0.1Pa.
The Mg of embodiment 5 is measured by XRD2Si/SiC composite thermoelectric material samples, its result show
Show, the Mg containing 20vol%SiC after the sintering2Only existed in Si/SiC composite thermoelectric material samples
SiC and Mg2Si diffraction maximum, this illustrates SiC and Mg in sample2Si is present in the form of compound.
The density of the sample of embodiment 5 is measured, the results are shown in Table 1.Measurement the sample of embodiment 5 density be
The 97% of solid density, illustrate the Mg obtained by the inventive method2Si/SiC composite samples consistency is high.
The thermoelectric figure of merit ZT variation with temperature curves of the sample are determined, when test temperature is 725K,
ZT values are 0.01.
The sample of embodiment 5 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 5
Hardness significantly improves.
Embodiment 6
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=40:60 Mg2The compound thermoelectricity of Si/SiC
Material (that is, the SiC comprising 40vol% and 60vol% Mg2S Mg2The compound thermoelectricity materials of Si/SiC
Material) and preparation method thereof.
Specifically, Mg2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 5 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintered 8 hours at 530 DEG C,
So as to which Mg be made2Si。
(3) 0.4612g high-purity alpha-SiC powder is weighed in the glove box that Ar atmosphere is enclosed, and (crystal formation is
6H-SiC, average grain diameter 40nm) and Mg made from (2) the step of 0.4324g2Si powder,
Interval ball milling 3 hours in the ball grinder of steel are placed in, so as to which Mg be made2Si/SiC mixed-powders,
Wherein the rotating speed of ball grinder is 8000 revs/min.
(4) obtained Mg in the step of taking 0.7g (3)2Si/SiC mixed-powders, utilize plasma
Body discharge sintering method sinters, so as to which the block composite thermoelectric material containing 40vol%SiC be made；Its
In, sintering condition is：Sample pressure is 70MPa, and sintering temperature is 900 DEG C, and sintering time is
10 minutes, chamber pressure was in below 0.1Pa.
The Mg of embodiment 6 is measured by XRD2Si/SiC composite thermoelectric material samples, its result show
Show, the Mg containing 40vol%SiC after the sintering2Only existed in Si/SiC composite thermoelectric material samples
SiC and Mg2Si diffraction maximum, this illustrates SiC and Mg in sample2Si is present in the form of compound.
The density of the sample of embodiment 6 is measured, its density is the 97% of solid density, is illustrated by the present invention
The Mg that method obtains2Si/SiC composite samples consistency is high.
The thermoelectric figure of merit ZT variation with temperature curves of the sample are determined, when test temperature is 725K,
ZT values are 0.008.
The sample of embodiment 6 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 6
Hardness significantly improves.
Embodiment 7
It is SiC that the present embodiment, which is used to describe volume ratio,：Mg2Si=40:The Mg of 60 Sb doping2Si/SiC
Composite thermoelectric material (that is, the SiC comprising 40vol% and 60vol% Mg2S Sb doping
Mg2Si/SiC composite thermoelectric materials) and preparation method thereof.
Specifically, the Mg of Sb doping2The preparation method of Si/SiC composite thermoelectric materials comprises the following steps：
(1) it is Mg by atomic ratio in the glove box that Ar atmosphere is enclosed：Si=2.1:1 weigh high purity magnesium and
Silicon raw material, interval ball milling 3 hours in the ball grinder of steel are placed in, the wherein rotating speed of ball grinder is 8000
Rev/min.
(2) by the material powder tabletting after ball milling mixing in step (1), it is placed in alumina crucible,
And enclose in the quartz ampoule of the Ar gas filled with 0.2 atmospheric pressure, then sintering 8 is small at 530 DEG C
When, so as to which Mg be made2Si。
(3) 0.4612g N doping SiC powder (current-carrying is weighed in the glove box that Ar atmosphere is enclosed
Sub- concentration 1018/cm3, crystal formation 6H-SiC, average grain diameter 40nm), 0.4324g the step of
(2) Mg made from2Si powder and 0.0034g Sb powder, it is placed in interval in the ball grinder of steel
Ball milling 3 hours, so as to which the Mg containing Sb be made2The rotating speed of Si/SiC mixed-powders, wherein ball grinder
For 8000 revs/min.
(4) the obtained Mg containing Sb in the step of taking 0.7g (3)2Si/SiC mixed-powders,
Sintered using plasma discharge sintering process, so as to which the block doping containing 40vol%SiC be made
Conductive composite thermoelectric material；Wherein, sintering condition is：Sample pressure is 70MPa, and sintering temperature is
900 DEG C, sintering time is 10 minutes, and chamber pressure is in below 0.1Pa.
The Mg of embodiment 7 is measured by XRD2Si/SiC composite thermoelectric material samples, its result show
Show, the doping of the Sb containing the 40vol%SiC Mg after the sintering2In Si/SiC composite thermoelectric material samples
Only exist SiC and Mg2Si diffraction maximum, illustrate SiC and Mg in sample2Si is in the form of compound
In the presence of.It is not intended to bound by theory, it is believed that Sb is doped into the structure cell of sample, so as to be advantageous to carry
The electric conductivity of high material.
The density of the sample of embodiment 7 is measured, its density is the 97% of solid density, is illustrated by the present invention
The Sb doping Mg that method obtains2The consistency of Si/SiC composite thermoelectric material samples is high.
The thermoelectric figure of merit ZT variation with temperature curves of determination sample, when test temperature is 725K,
ZT values are 0.18.
The sample of embodiment 7 is fallen on marble slab from 2 meters of height, sample is not broken.And in phase
With under the conditions of, Mg2Si samples are broken.The material of this explanation present invention is not easy to break.In addition,
Using its hardness of scarification observational measurement, it is found that with Mg2Si materials are compared, the sample of embodiment 7
Hardness significantly improves.
The solid density and measurement density of the embodiment sample of table 1
| SiC content | MMg2Si(g) | MSiC(g) | ρexpt(g/cm3) | ρther(g/cm3) | |
| Embodiment 1 | 5vol% | 1.0012 | 0.0843 | 2.02 | 2.06 |
| Embodiment 2 | 10vol% | 0.7025 | 0.1249 | 2.07 | 2.12 |
| Embodiment 3 | 15vol% | 0.6343 | 0.1791 | 2.14 | 2.18 |
| Embodiment 4 | 15vol% | 0.6343 | 0.1791 | 2.14 | 2.18 |
| Embodiment 5 | 20vol% | 0.8432 | 0.3373 | 2.18 | 2.24 |
| Embodiment 6 | 40vol% | 0.4324 | 0.4612 | 2.41 | 2.48 |
| Embodiment 7 | 40vol% | 0.4324 | 0.4612 | 2.41 | 2.48 |
Note：ρtherRepresentation theory density, ρexptRepresent measurement density.
The synthetic schemes of the present invention is described above with reference to specific embodiment, people in the art
Member is and non-limiting it is understood that the various parameters in above-described embodiment are exemplary only,
Those skilled in the art can make various modifications according to synthetic schemes provided by the invention.This area
It is to be appreciated by one skilled in the art that being modified or equivalent substitution to the synthetic schemes of the present invention, all
The spirit and scope of synthetic schemes of the present invention are not departed from, it all should cover in scope of the presently claimed invention
It is central.
Claims (10)
1. a kind of composite thermoelectric material, the composite thermoelectric material includes SiC, Mg2Si and optional
Doped chemical Sb, wherein, SiC and Mg2Si volume ratio is 5:95-40:60, and doped chemical
Sb and Mg2Si mol ratio 0-0.03：1.
2. composite thermoelectric material according to claim 1, wherein, the composite thermoelectric material is
The form of the dense body of sintering；
Preferably, the density of the composite thermoelectric material is the 95% or higher of its solid density；
It is highly preferred that the density of the composite thermoelectric material is the 97% or higher of its solid density.
3. composite thermoelectric material according to claim 1 or 2, wherein, SiC and Mg2Si's
Volume ratio is 5:95-20:80, preferably 5:95-15:85；
Preferably, Sb and Mg2Si mol ratio is 0.005-0.03：1, preferably 0.005-0.015：
1。
4. composite thermoelectric material according to any one of claim 1 to 3, wherein, it is described
One or more of the SiC in 4H-SiC, 6H-SiC and 3C-SiC；And/or
The SiC is that n-type adulterates SiC, the SiC of preferably N doping.
5. the method for the composite thermoelectric material any one of Claims 1-4 is prepared, wherein,
Methods described includes：
(1) by SiC powder, Mg2Si powder and optional Sb powder carry out ball milling mixing, so as to
Mixed-powder is made；With
(2) mixed-powder made from plasma discharge sintering process sintering step (1) is utilized, so as to
Composite thermoelectric material is made.
6. according to the method for claim 5, wherein, the average grain diameter of the SiC powder is
Below 100nm, preferably 40-100nm；
Preferably, Mg2Si powder average particle sizes are in below 100nm, preferably 40-100nm.
7. the method according to claim 5 or 6, wherein, the ball milling described in step (1)
It is blended in progress 3-5 hours under 7500-10000 revs/min of rotating speed；
Preferably, the ball milling mixing described in step (1) is carried out in a manner of interval ball milling.
8. the method according to any one of claim 5 to 7, wherein, institute in step (1)
The Mg stated2Si powder is prepared by the method comprised the following steps：
(a) it is Mg by atomic ratio：Si=2.1-2.2:1, magnesium and silicon raw material are weighed, is placed in ball grinder
Middle interval ball milling 3-5 hours；
(b) by the raw material tabletting after ball milling in step (a), and under an argon atmosphere in 500-550 DEG C,
5-10 hours are sintered preferably at a temperature of 530 DEG C, so as to which Mg be made2Si。
9. according to the method for claim 8, interval ball milling described in step (a) exists
7500-10000 revs/min, preferably carried out under 8000 revs/min of rotating speed；
Preferably, the pressure of argon gas is 0.2-0.3 atmospheric pressure in step (b).
10. the method according to any one of claim 5 to 9, wherein, institute in step (2)
The condition for the plasma discharge sintering process stated is as follows：Vacuum is in below 0.1Pa, sample pressure
60-70MPa, sintering temperature are 700-900 DEG C, preferably 750-900 DEG C, and sintering time is 8-15
Minute.
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| JP7359412B2 (en) | 2019-03-29 | 2023-10-11 | 学校法人東京理科大学 | Polycrystalline magnesium silicide, sintered body and its use |
| CN117069500A (en) * | 2023-08-14 | 2023-11-17 | 陕西科技大学 | Magnesium silicide thermoelectric semiconductor material and preparation method and application thereof |
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| CN108198934A (en) * | 2017-12-28 | 2018-06-22 | 长沙善道新材料科技有限公司 | A kind of composite thermoelectric material and preparation method thereof |
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| JP7359412B2 (en) | 2019-03-29 | 2023-10-11 | 学校法人東京理科大学 | Polycrystalline magnesium silicide, sintered body and its use |
| CN111211215A (en) * | 2020-03-06 | 2020-05-29 | 杨锦祯 | Nano composite thermoelectric material and preparation method thereof |
| CN117069500A (en) * | 2023-08-14 | 2023-11-17 | 陕西科技大学 | Magnesium silicide thermoelectric semiconductor material and preparation method and application thereof |
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