CN101101955A

CN101101955A - Alloy pole for cobalt antimonides-based thermal electrical part and part making method

Info

Publication number: CN101101955A
Application number: CNA2007100433898A
Authority: CN
Inventors: 陈立东; 赵德刚; 李小亚; 赵雪盈; 周燕飞; 柏胜强; 夏绪贵
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2007-07-03
Filing date: 2007-07-03
Publication date: 2008-01-09

Abstract

The invention is concerned with the electrode alloy pyroelectricity device of the cobalt antimonide pyroelectricity device and it's making method. It includes the Cu-W alloy electrode with the W quality percentage 20% to 30%; the rest components are copper and unavoidable impurity; the optimized Cu75W25 electrode hot coefficient of expansion (CTE) and the CoSb3 pyroelectricity are in right hot matching with difference no more than 9.8%. The component making applies the transition layer of the metal Ti, granularity about 20-50mum, and the discharge plasma sintering (SPS) method to achieve the connection of the Cu-W alloy electrode and the pyroelectricity. Because of the high conductivity and the thermal conductivity of the copper tungsten alloy and it is matching with the CoSb3 pyroelectricity material rightly, the invention is with the quite stable surface with no obvious composition plane electrode transition, keeps the making method simple.

Description

A kind of alloy electrode and part making method that is used for cobalt antimonides-based thermal electrical part

Technical field

The present invention relates to a kind of alloy electrode and part making method that is used for cobalt antimonides-based thermal electrical part, relate to the method for attachment of electrode material and the electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part or rather, belong to the preparing technical field of thermoelectric components and parts.

Background technology

The thermoelectric material functional material that to be a kind of Seebeck of utilization effect and Peltier effect transform heat energy and electric energy mutually; do not need the mechanical movement position when working by the thermoelectric device of thermoelectric material preparation; chemical reaction does not take place yet; it is long to have a life-span; the reliability height; advantages such as environmentally safe, along with increasing the weight of day by day of global environmental pollution and energy crisis, thermoelectric device is subjected to the attention of various countries' research day by day.At present, about the thermoelectric material Element Technology of cryogenic cooling suitable ripe such as bismuth telluride and be widely used in commodity production for example, the thermoelectric material of middle high temperature such as the components and parts of preparations such as PbTe, SiGe also begin to be applied to space field in developed countries such as the U.S. at present.Antimony cobalt-based thermoelectric material because of its special electronic structure be considered to the most promising in warm electricity generation material, the P type that mixes or fill, its thermoelectric figure of merit of antimony cobalt-based thermoelectric material (ZT) of N type have all reached more than 1.0, but its components and parts technology of preparing is still far from perfect, and particularly relates to the difference that electrode is connected owing to thermal coefficient of expansion with the antimony cobalt and has very big difficulty.

Select major requirement to have following characteristic to the electrode of thermoelectric material components and parts: in the serviceability temperature scope, not have serious counterdiffusion mutually or reaction, thereby guarantee that the thermoelectric material self performance is unaffected with corresponding thermoelectric material; Higher conductivity and thermal conductivity are arranged to reduce energy loss; To have certain non-oxidizability in the serviceability temperature scope to guarantee the reliability and the useful life of device; Thereby being the thermal coefficient of expansion and the corresponding thermoelectric material coupling of electrode material, the most important influences thermoelectric transmission performance with thermal stability to prevent to crack.

Low temperature thermoelectric unit spare generally selects for use Al etc. as electrode because the temperature range span is little, has selected for use Al (A1200, A1100, A1050 etc.) as electrode material as BiTe thermoelectric material among the patent documentation JP10012935.But for middle elevated temperature heat electrical component, because the temperature range span is bigger, and the long-term work of thermoelectric device hot junction is under hot conditions, electrode material and thermoelectric material be because the difference of thermal coefficient of expansion (CTE) and very easily cracking at the interface, therefore selects for the electrode of middle elevated temperature heat electrical component and be connected technology higher requirement is arranged.In patent documentation JP11274580, the PbTe thermoelectric material has adopted the Cu electrode, and among the patent documentation JP2000100751, the SiC thermoelectric material is also selected the Cu electrode for use.The research for antimony cobalt-based thermoelectric material device at present is in laboratory stage, and most of cobalt stibium antimonide based thermoelectric device electrodes have also adopted the Cu electrode, as patent documentation JP2004063585, and in fact Cu and CoSb ₃CTE difference excessively (be respectively 18 * 10 100 ℃ the time ^-6K ^-1With 10 * 10 ^-6K ^-1), be easy to cause the cracking of electrode and thermoelectric material.Have only U.S. jet power laboratory (JetPropulsion Laboratory) once when the 20th International Conference onThermoelectrics reports list to the thermoelectric power generation of antimony cobalt-based, to adopt metal Ti abroad as electrode, do not add elaboration for concrete preparation technology, be in the secret stage.Ti is that conductivity is relative with thermal conductivity higher as the shortcoming of electrode, and energy consumption is bigger, and non-oxidizability is poor.A large amount of work has been done by domestic Shanghai Silicate Inst., Chinese Academy of Sciences on the preparation of antimony cobalt-based thermoelectric material and element manufacturing, especially be connected with the reliability of electrode material to have done targetedly and study at selection of electrode materials and antimony cobalt-based thermoelectric material, as in CN1585145 and 200710037778.X (application number), adopt metal M o or Mo-Cu alloy as electrode material, adopt diverse ways to prepare antimony cobalt-based thermoelectric material components and parts, the present invention intends further optimizing on this basis the heat coupling, the more good Cu-W alloy electrode material of hot coupling has been proposed, utilize SPS (plasma discharging) sintering method to prepare antimony cobalt-based thermoelectric material components and parts, realized good being connected of electrode material with antimony cobalt-based thermoelectric material.

Summary of the invention

The object of the invention is to provide a kind of preparation method who is used for the alloy electrode and the thermoelectric element of cobalt antimonides-based thermal electrical part, be that the present invention puies forward the good Cu-W alloy electrode of a kind of and antimony cobalt-based thermoelectric material heat coupling and the technology that is connected of electrode and antimony cobalt-based thermoelectric material, thereby it is good to prepare interface electrical property transition, interface reliability height and the easy cobalt antimonides-based thermal electrical part of technology.

The present invention selects for use copper-tungsten (Cu-W) to do electrode, copper-tungsten made at 1400 ℃ of high temperature hot pressed sinterings in 1-2 hour, the microstructure of copper-tungsten owing to can freely design on the thermal expansion matching, has been avoided single Cu electrode because the excessive micro-crack that causes of thermal coefficient of expansion as shown in Figure 1.Mensuration knows that antimony cobalt thermoelectric material thermal coefficient of expansion is in 10-11 * 10 in 100-600 ℃ of temperature range ^-6K ^-1In the scope, the Cu-W alloy electrode component that is provided is that the content of tungsten is 20-30%, and surplus is copper and a small amount of unavoidable impurities, and best composition is the quality percentage composition 25% of tungsten, and surplus is copper and impurity, and note is made Cu ₇₅W ₂₅, also i.e. Cu after optimal design of the present invention ₇₅W ₂₅The electrode thermal expansion coefficient in 100-600 ℃ of temperature range basically in 9-11 * 10 ^-6K ^-1In the scope, its CTE difference maximum only has 9.8%, described Cu ₇₅W ₂₅Electrode material and CoSb ₃The thermal coefficient of expansion of thermoelectric material more as shown in Figure 2.Owing to obtained very good heat coupling, will reduce greatly like this because electrode in the thermal stress that produces at the interface, will farthest improve the useful life of cobalt stibium antimonide based thermoelectric device with the different of antimony cobalt-based thermoelectric material thermal expansion.

The electrode that the present invention selects for use with the processing step that the CoSb3 thermoelectric material adopts SPS to be connected is: at first Cu-W alloy electrode sheet metal is through blasting treatment, make its surface have certain roughness, sonicated is removed its surperficial impurity then, puts it in the graphite jig.Particle diameter is evenly covered the surface of electrode metal sheet at the Ti powder of 20-50 μ m, spread CoSb more equably on Ti powder surface then ₃Powder, carry out discharge plasma sintering in the vacuum, vacuum degree is 1Pa-15Pa, programming rate is controlled at 80-150 ℃/min, sintering temperature is 550-600 ℃, sintering pressure is at 30-60MPa, and temperature retention time utilized the SPS method that antimony cobalt thermoelectric material and Cu-W alloy electrode good binding are in the same place at 10-30 minute.Use as the Ti layer of transition zone as resilient coating, is because Ti and CoSb on the one hand ₃Can form alloy-layer, the introducing of Ti transition zone simultaneously also becomes semiconductor and being connected of metal being connected of metal and metal, and the Ti layer about 50-200 μ m can not introduced too big interface resistance and thermal resistance yet on the other hand.Described Cu-W electrode metal sheet thickness is 1-3mm.

This shows, the invention provides a kind of and good alloy electrode and element electrode and the CoSb of antimony cobalt-based thermoelectric material heat coupling ₃Interconnection technique technology, its maximum characteristics are to finish connection by discharge plasma sintering is once sintered, the composition surface does not have the transition of sharp interface resistance, combination interface is good, good reliability and technological operation are easy, and, make be improved useful life because the good heat coupling of electrode and thermoelectric material will farthest reduce the generation of thermal stress at the interface.

Description of drawings

Fig. 1 is thermal coefficient of expansion and CoSb ₃The Cu that material is complementary ₇₅W ₂₅The microstructure of electrode.

Fig. 2 is CoSb ₃With the thermal coefficient of expansion comparison diagram of Cu-W electrode at 100-600 ℃.

Fig. 3 is Cu-W electrode/CoSb in the thermoelectric element ₃The sem photograph at interface.

Fig. 4 is Cu-W electrode/CoSb in the thermoelectric element ₃The sem photograph of the various elements in interface, Fig. 4 (a) is the ESEM of institute's favored area; Fig. 4 (b) is the vegetarian noodles scanning of the favored area W of institute unit; Fig. 4 (c) is the first vegetarian noodles scanning of selected zone C u; Fig. 4 (d) is the first vegetarian noodles scanning of selected zone C o; Fig. 4 (e) is the first vegetarian noodles scanning of selected region S b; Fig. 4 (f) is the vegetarian noodles scanning of the favored area Ti of institute unit.

Fig. 5 is a phase boundary potential changes in distribution situation, and wherein abscissa is a test position, and unit is mm, and ordinate is voltage V, and unit is mV.

Embodiment

Below by instantiation substantive distinguishing features of the present invention and obvious improvement are described, but the present invention only is confined to embodiment by no means.

Embodiment 1

The copper tungsten electrode consists of Cu ₇₅W ₂₅Thickness 1mm, at first blasting treatment 2 minutes in sand-blasting machine of surface, sonicated is 10 minutes then, the copper tungsten electrode is put into the graphite jig of Φ 10, spread the titanium valve of granularity uniformly at electrode surface, then press antimony cobalt thermoelectric material, preload pressure 10MPa uniformly in advance at 20 μ m, carry out the SPS sintering then, vacuum degree 1Pa, sintering pressure are 30MPa, and heating rate is 80 ℃/min, sintering temperature is 600 ℃, is incubated 10min then and finishes sintering.

Resulting Cu-W electrode/CoSb ₃Block is through scanning electron microscopic observation, the interface is in conjunction with good, do not see the crackle (see figure 3) is arranged, electron probing analysis shows and does not have tangible interfacial diffusion between antimony cobalt-based thermoelectric material and electrode interface that Fig. 4 a shows device interfaces selected sector scanning Electronic Speculum figure and W, Cu respectively to Fig. 4 f, Ti, Co, the face of Sb element distributes, by contrasting as can be seen at CoSb among the figure ₃/ Ti interlayer has formed a TiSb alloy-layer that approaches, and this should be to form owing to Sb in the SPS process diffuses into the Ti layer.Adopt four termination electrode methods that the interface zone Potential Distributing is measured, the mild transition of electromotive force on the interface as can be seen, maximum potential difference only is 15 μ V when electric current is 10mA, there is not big electromotive force transition, illustrate from the side that also tangible resistance transition (see figure 5) is not taking place resistance at the interface, 500 hours thermal fatigue test rear interface microstructures and phase boundary potential do not have significant change, have illustrated to utilize SPS to connect the Cu-W electrode and thermoelectric material can stand long thermal fatigue test.

Embodiment 2

Copper tungsten electrode component is Cu ₈₀W ₂₀Thickness 2mm, with with embodiment 1 in identical method and condition electrode is handled, the copper tungsten electrode is put into the graphite jig of Φ 10, spread the titanium valve of granularity 40 μ m equably at electrode surface, then press antimony cobalt thermoelectric material equably in advance, preload pressure 10MPa carries out SPS sintering, vacuum degree 7Pa then, sintering pressure is 50MPa, heating rate is 120 ℃/min, and sintering temperature is 580 ℃, is incubated 20min then and finishes sintering.

Resulting Cu-W electrode/CoSb ₃Block finds no crackle through scanning electron microscopic observation, and electron probing analysis antimony cobalt-based thermoelectric material and electrode interface do not have tangible interfacial diffusion, and tangible electromotive force transition does not take place interfacial potential.

Embodiment 3

Copper tungsten electrode Cu ₇₀W ₃₀Thickness 3mm, with with embodiment 1 in identical method and condition electrode is handled, the copper tungsten electrode is put into the graphite jig of Φ 10, spread the titanium valve of granularity 50 μ m uniformly at electrode surface, then press antimony cobalt thermoelectric material uniformly in advance, preload pressure 10MPa carries out SPS sintering, vacuum degree 15Pa then, sintering pressure is 60MPa, heating rate is 150 ℃/min, and sintering temperature is 550 ℃, is incubated 30min then and finishes sintering.

Resulting Cu-W electrode/CoSb ₃Block is not found crackle through scanning electron microscopic observation, and electron probing analysis antimony cobalt-based thermoelectric material and electrode interface do not have tangible interfacial diffusion, and tangible electromotive force transition does not take place interfacial potential.

Claims

1, a kind of alloy electrode that is used for cobalt antimonides-based thermal electrical part is characterized in that described alloy electrode is the Cu-W alloy, and wherein the quality percentage composition of W is 20%-30%, and surplus is copper and a small amount of unavoidable impurities.

2, by the described alloy electrode that is used for cobalt antimonides-based thermal electrical part of right 1 requirement, the quality percentage composition that it is characterized in that W in the described Cu-W alloy electrode is 25%, and surplus is Cu and a small amount of unavoidable impurities.

3, a kind of by claim 1 or the 2 described methods of attachment that are used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part, it is characterized in that connecting processing step and be:

(a) at first the Cu-W alloy electrode is made sheet metal, through blasting treatment, remove surface impurity with ultrasonic processing method, the quality percentage composition of W is 20%-30% in the Cu-W alloy electrode sheet metal, and surplus is Cu and a small amount of unavoidable impurities;

(b) step (a) Cu-W alloy electrode sheet metal is after treatment put into graphite jig, on the electrode metal sheet, evenly cover the Ti powder, spread CoSb more equably on Ti powder surface then as transition zone ₃Powder;

(c) carry out discharge plasma sintering in the vacuum, vacuum degree 1Pa-15Pa, sintering temperature 550-600 ℃, sintering pressure is 30-60Mpa, utilizes the plasma discharging method with CoSb ₃Thermoelectric material is connected with the Cu-W alloy electrode.

4,, it is characterized in that described Cu-W electrode metal sheet thickness is 1-3mm by the described method of attachment that is used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part of claim 3

5,, it is characterized in that employed Ti powder directly is 20-50 μ m by the described method of attachment that is used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part of claim 3.

6, by the described method of attachment that is used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part of claim 3, the programming rate when it is characterized in that discharge plasma sintering in the step (c) is 80-150 ℃/min.

7,, it is characterized in that the discharge plasma sintering temperature retention time is 10-30 minute in the step (c) by the described method of attachment that is used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part of claim 3.

8, by claim 3 or the 5 described methods of attachment that are used for the alloy electrode and the thermoelectric material of cobalt antimonides-based thermal electrical part, it is characterized in that described alloy electrode sheet metal and CoSb ₃Thermoelectric material connects, and the thickness of Ti transition zone is 50-200 μ m.