A high-thermal-stability welding method for skutterudite thermoelectric material / electrode based on a cermet composite barrier layer

Abstract

The application discloses a high-thermal-stability welding method for a skutterudite thermoelectric material / electrode based on a metal ceramic composite barrier layer, and relates to a connecting method for a skutterudite-based thermoelectric material and a metal electrode. In order to solve the problem that there is a strong element diffusion between the skutterudite and the metal electrode, so that the strength and the interface resistance are increased, and the welding joint strength is low and the service life is reduced. The application uses a metal ceramic composite phase as a diffusion barrier layer, and has high connecting strength, low joint resistance and slow thickness growth of a reaction layer under long-term service, so that good mechanical properties and use performance are maintained. The application can control the composition and proportion of the overall barrier layer by selecting different refractory metals and ceramics, can control the type, thickness and distribution mode of the interface reaction layer by controlling the welding temperature and holding time, and then control the strength and thermal / electric transport performance of the welding joint.

Description

TECHNICAL FIELD

[0001] The present application relates to a skutterudite thermoelectric material / electrode welding method. BACKGROUND

[0002] Thermoelectric materials are a kind of important materials with the function of converting thermal energy and electrical energy. With the Seebeck effect and Peltier effect, this kind of material has a wide application in thermoelectric power generation and thermoelectric refrigeration. Skutterudite thermoelectric material (hereinafter referred to as SKD) is a representative of medium-temperature thermoelectric materials, with a service temperature range of 300-600℃. It has great practical application potential due to its good thermoelectric performance and mechanical properties.

[0003] The last step of manufacturing thermoelectric devices is to connect the thermoelectric material with the metal electrode, but there is a strong element diffusion between the skutterudite and the metal electrode, which increases the strength and interface resistance, greatly reducing the service life. There is no barrier metal material that can meet the long-term service needs of skutterudite thermoelectric materials. Therefore, it is very important to design a method to realize the long-term reliable connection between skutterudite thermoelectric materials and metal electrodes.

[0004] The conventional metal barrier layer will appear brittle phase after being connected with the skutterudite. The addition of refractory metal can reduce the proportion of brittle phase to a certain extent, but it often leads to low connection strength due to the difference in thermal expansion coefficient. If other metals are added, they will react with the skutterudite, resulting in poor overall diffusion resistance effect. In summary, the reaction layer between the added barrier layer and the skutterudite has an interface resistivity greater than that of the base material, while the strength is lower than that of the base material, so reducing the thickness of the reaction layer is the core purpose of the barrier layer. Therefore, it is of great practical significance to invent a method for reliable connection between skutterudite-based thermoelectric materials and metal electrodes. SUMMARY

[0005] The present application is to solve the problem of strong element diffusion between skutterudite and metal electrode, which increases the strength and interface resistance, and thus reduces the strength of the welded joint and the service life.

[0006] The skutterudite thermoelectric material / electrode high-thermal-stability welding method based on the metal-ceramic composite barrier layer is carried out according to the following steps:

[0007] First, the skutterudite thermoelectric material is hot-pressed and sintered with the barrier layer to obtain a skutterudite with a pre-installed barrier layer. The surface of the barrier layer in the skutterudite with a pre-installed barrier layer is the welding surface. The welding surfaces of the skutterudite with a pre-installed barrier layer and the metal electrode are pretreated respectively. Finally, the treated skutterudite with a pre-installed barrier layer and the metal electrode are stored in an oxygen-free or inert atmosphere.

[0008] The method for preparing the skutterudite with a pre-set barrier layer comprises: spreading a layer of skutterudite powder in a graphite mold, then spreading a layer of metal-ceramic composite barrier layer powder on the skutterudite powder, and finally performing hot pressing and sintering;

[0009] The hot pressing sintering process is as follows: in a vacuum environment, the applied pressure is 40-70 MPa, the temperature is raised to 650-760°C at a rate of 10-20°C / min and kept at this temperature for 5-30 minutes, and then cooled to room temperature at a rate of 20-50°C / min;

[0010] The metal-ceramic composite barrier layer powder is made of a mixture of refractory metal powder and ceramic powder; the refractory metal powder is one or more of Mo, V, Zr, Nb, Ta, Re, and Ti; the ceramic powder is M x Si y 、M x N y 、M x O y One or more of, wherein M is one or more of Ti, Zr, Mg, Al, K, Ca, Zn, and Mn; the molar percentage of the refractory metal powder in the metal-ceramic composite barrier layer powder is 60%-90%;

[0011] 2. Assemble the skutterudite with a pre-set barrier layer and the metal electrode, with the surface to be welded of the skutterudite with the pre-set barrier layer facing the surface to be welded of the metal electrode, place a brazing filler metal between the surface to be welded of the skutterudite with the pre-set barrier layer and the surface to be welded of the electrode, and finally weld the parts to be welded; the welding process is as follows: in a vacuum degree of 5×10 -3 In a vacuum brazing furnace below Pa, heat to 600-700℃ at a rate of 10-20℃ / min and keep warm for 5-30min, then cool to room temperature at a rate of 10-50℃ / min.

[0012] The metal ceramic composite barrier layer powder in the application is mixed by refractory metal powder and ceramic powder, and forms a metal ceramic composite phase after hot-pressing sintering. The metal ceramic composite phase as a barrier layer has no serious interface reaction with skutterudite series thermoelectric materials and metal electrodes in the welding process, and element diffusion is slow in the metal ceramic composite phase. Compared with the existing Ti barrier layer, the brittle reaction layer of the metal ceramic composite phase is reduced in overall proportion, and the reaction layer is also thinned as a whole. The high thermal expansion coefficient of the ceramic in the metal ceramic composite phase adjusts the overall thermal expansion coefficient, and the connection strength is higher. The addition of the ceramic also avoids the problem that the adjustment of the thermal expansion coefficient by other metals will react with skutterudite, without damaging the overall diffusion barrier effect. Therefore, the application has high connection strength with the metal ceramic composite phase as the diffusion barrier layer, low joint resistance, slow thickness growth of the reaction layer under long-term service, and thus maintains good mechanical properties and use performance. The application can adjust the composition and proportion of the overall barrier layer by selecting different refractory metals and ceramics, and can control the type, thickness and distribution mode of the interface reaction layer by controlling the welding temperature and holding time, so as to control the strength and thermal / electric transport performance of the welded joint.

[0013] Another skutterudite thermoelectric material / electrode high-temperature stable welding method based on the metal ceramic composite barrier layer of the application is carried out according to the following steps:

[0014] I. First, the skutterudite powder is hot-pressed and sintered into skutterudite, and the metal ceramic composite barrier layer powder is hot-pressed and sintered into a pre-positioned barrier layer; then the surfaces to be welded of the skutterudite, the surfaces to be welded of the metal electrode, and the two surfaces of the pre-positioned barrier layer are pretreated; finally, the treated skutterudite, metal electrode and pre-positioned barrier layer are stored in an oxygen-free or inert atmosphere;

[0015] The process of hot-pressing and sintering the skutterudite powder into skutterudite is: in a vacuum environment, the applied pressure is 40-70 MPa, the temperature is raised to 650-760℃ at a rate of 10-20℃ / min and held for 5-30 min, and then cooled to room temperature at a rate of 20-50℃ / min;

[0016] The process of hot-pressing and sintering the metal ceramic composite barrier layer powder into a pre-positioned barrier layer is: in a vacuum environment, the applied pressure is 40-70 MPa, the temperature is raised to 650-760℃ at a rate of 10-20℃ / min and held for 5-30 min, and then cooled to room temperature at a rate of 20-50℃ / min;

[0017] The metal ceramic composite barrier layer powder is mixed by refractory metal powder and ceramic powder; the refractory metal powder is one or more of Mo, V, Zr, Nb, Ta, Re and Ti; the ceramic powder is M xSi y , M x N y , M x O y , wherein M is one or more of Ti, Zr, Mg, Al, K, Ca, Zn, Mn; the molar percentage of the refractory metal powder in the cermet composite barrier layer powder is 60%-90%;

[0018] II. The pre-set barrier layer is placed between the rhombohedral cobaltite surface to be welded and the surface of the metal electrode to be welded to obtain a welding part, and finally welding is performed; the welding process is: in a vacuum brazing furnace with a vacuum degree of 5*10 -3 Pa, a pressure of 5-20 MPa is applied, the temperature is raised to 600-700 DEG C at a rate of 10-20 DEG C / min and kept for 5-30 min, and then the temperature is lowered to room temperature at a rate of 10-50 DEG C / min.

[0019] In the present application, the cermet composite barrier layer powder is mixed by refractory metal powder and ceramic powder, and the cermet composite phase is formed after hot pressing sintering. The cermet composite phase as a barrier layer has no serious interface reaction with rhombohedral cobaltite-based thermoelectric materials and metal electrodes in the welding process, and the element diffusion is slow in the cermet composite phase. At the same time, compared with the existing Ti barrier layer, the overall proportion of the brittle reaction layer of the cermet composite phase is reduced, and the reaction layer is also thinned. The high thermal expansion coefficient of the ceramic in the cermet composite phase adjusts the overall thermal expansion coefficient, and the connection strength is higher. The addition of the ceramic also avoids the problem that the adjustment of the thermal expansion coefficient by other metals will react with rhombohedral cobaltite, without damaging the overall diffusion barrier effect. Therefore, the present application has high connection strength with the cermet composite phase as the diffusion barrier layer, low joint resistance, slow growth of the reaction layer thickness after 135h annealing, and thus maintains good mechanical properties and use performance. The present application can control the composition and proportion of the overall barrier layer by selecting different refractory metals and ceramics, and can control the type, thickness and distribution mode of the interface reaction layer by controlling the welding temperature and holding time, thereby controlling the strength and thermal / electric transport performance of the welded joint. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 SEM image of the welded interface of the cermet composite phase / rhombohedral cobaltite thermoelectric material obtained in Example 1;

[0021] Figure 2 SEM image of the welded interface of the cermet composite phase / rhombohedral cobaltite thermoelectric material obtained in Example 1 after 135h annealing. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is not limited to the specific implementation methods listed below, but also includes any reasonable combination of the specific implementation methods.

[0023] Specific embodiment 1: The high thermal stability welding method of skutterudite thermoelectric material / electrode based on metal-ceramic composite barrier layer in this embodiment is carried out according to the following steps:

[0024] 1. First, hot-pressing and sintering the skutterudite thermoelectric material and the barrier layer to obtain a skutterudite with a pre-barrier layer; the surface of the barrier layer in the skutterudite with the pre-barrier layer is the surface to be welded, and the surface to be welded of the skutterudite with the pre-barrier layer and the surface to be welded of the metal electrode are pre-treated respectively; finally, the treated skutterudite with the pre-barrier layer and the metal electrode are stored in an oxygen-free or inert atmosphere;

[0025] The method for preparing the skutterudite with a pre-set barrier layer comprises: spreading a layer of skutterudite powder in a graphite mold, then spreading a layer of metal-ceramic composite barrier layer powder on the skutterudite powder, and finally performing hot pressing and sintering;

[0026] The hot pressing sintering process is as follows: in a vacuum environment, the applied pressure is 40-70 MPa, the temperature is raised to 650-760°C at a rate of 10-20°C / min and kept at this temperature for 5-30 minutes, and then cooled to room temperature at a rate of 20-50°C / min;

[0027] The metal-ceramic composite barrier layer powder is made of a mixture of refractory metal powder and ceramic powder; the refractory metal powder is one or more of Mo, V, Zr, Nb, Ta, Re, and Ti; the ceramic powder is M x Si y 、M x N y 、M x O y One or more of, wherein M is one or more of Ti, Zr, Mg, Al, K, Ca, Zn, and Mn; the molar percentage of the refractory metal powder in the metal-ceramic composite barrier layer powder is 60%-90%;

[0028] 2. Assemble the skutterudite with a pre-set barrier layer and the metal electrode, with the surface to be welded of the skutterudite with the pre-set barrier layer facing the surface to be welded of the metal electrode, place a brazing filler metal between the surface to be welded of the skutterudite with the pre-set barrier layer and the surface to be welded of the electrode, and finally weld the parts to be welded; the welding process is as follows: in a vacuum degree of 5×10 -3 In a vacuum brazing furnace below Pa, heat to 600-700℃ at a rate of 10-20℃ / min and keep warm for 5-30min, then cool to room temperature at a rate of 10-50℃ / min.

[0029] In the embodiment, the cermet composite barrier layer powder is mixed by refractory metal powder and ceramic powder, and a cermet composite phase is formed after hot-pressing sintering. The cermet composite phase as the barrier layer has no serious interface reaction with the skutterudite thermoelectric material and the metal electrode in the welding process, and the element diffusion is slow in the cermet composite phase. Compared with the existing Ti barrier layer, the brittle reaction layer of the cermet composite phase in the embodiment has a reduced overall proportion and a thinned reaction layer. The high thermal expansion coefficient of the ceramic in the cermet composite phase adjusts the overall thermal expansion coefficient, and the connection strength is higher. The addition of the ceramic also avoids the problem that the adjustment of the thermal expansion coefficient by other metals will react with the skutterudite, without damaging the overall barrier diffusion effect. Therefore, the embodiment has high connection strength of the diffusion barrier layer with the cermet composite phase, low joint resistance, slow growth of the reaction layer thickness under long-term service, and thus good mechanical properties and use performance. The embodiment can adjust the composition and proportion of the overall barrier layer by selecting different refractory metals and ceramics, and can control the type, thickness and distribution of the interface reaction layer by controlling the welding temperature and holding time, thereby controlling the strength and thermal / electric transport performance of the welded joint.

[0030] Specific embodiment two: The difference between the embodiment and the specific embodiment one is that the pretreatment process in step one is: sequentially polishing, polishing, cleaning and drying the surface to be welded by using metallographic sandpaper step by step; the cleaning uses ethanol or acetone.

[0031] Specific embodiment three: The difference between the embodiment and the specific embodiment one or two is that the barrier layer thickness in step one is 20-200 μm.

[0032] Specific embodiment four: The difference between the embodiment and any one of the specific embodiments one to three is that the metal electrode in step one is Cu, Cu-based alloy, Ni, Ni-based alloy, Fe or Fe-based alloy.

[0033] Specific embodiment five: The difference between the embodiment and any one of the specific embodiments one to four is that the solder in step two is a copper-based soldering paste.

[0034] Specific embodiment six: The skutterudite thermoelectric material / electrode high-thermal-stability welding method based on the cermet composite barrier layer is carried out according to the following steps:

[0035] I. First, the skutterudite powder is hot-pressed and sintered into skutterudite, and the cermet composite barrier layer powder is hot-pressed and sintered into a pre-positioned barrier layer; then the surfaces to be welded of the skutterudite, the surfaces to be welded of the metal electrode, and the two surfaces of the pre-positioned barrier layer are pretreated; finally, the treated skutterudite, metal electrode and pre-positioned barrier layer are stored in an oxygen-free or inert atmosphere;

[0036] The process of hot-press sintering the skutterudite powder into skutterudite is: under vacuum, applying a pressure of 40-70 MPa, heating at a rate of 10-20 ℃ / min to 650-760 ℃ and holding for 5-30 min, and then cooling at a rate of 20-50 ℃ / min to room temperature;

[0037] The process of hot-press sintering the cermet composite barrier layer powder into the pre-set barrier layer is: under vacuum, applying a pressure of 40-70 MPa, heating at a rate of 10-20 ℃ / min to 650-760 ℃ and holding for 5-30 min, and then cooling at a rate of 20-50 ℃ / min to room temperature;

[0038] The cermet composite barrier layer powder is mixed from refractory metal powder and ceramic powder; the refractory metal powder is one or several of Mo, V, Zr, Nb, Ta, Re and Ti; the ceramic powder is one or several of SiO2, Al2O3, MgO, K2O, CaO, ZnO and MnO, wherein M is one or several of Ti, Zr, Mg, Al, K, Ca, Zn and Mn; the molar percentage of the refractory metal powder in the cermet composite barrier layer powder is 60%-90%; x Si y , M x N y , M x O y , wherein M is one or several of Ti, Zr, Mg, Al, K, Ca, Zn and Mn; the molar percentage of the refractory metal powder in the cermet composite barrier layer powder is 60%-90%;

[0039] II. Placing the pre-set barrier layer between the skutterudite to-be-welded surface and the metal electrode to-be-welded surface to obtain a to-be-welded piece, and finally performing welding; the welding process is: in a vacuum brazing furnace with a vacuum degree of 5×10 -3 Pa or less, applying a pressure of 5-20 MPa, heating at a rate of 10-20 ℃ / min to 600-700 ℃ and holding for 5-30 min, and then cooling at a rate of 10-50 ℃ / min to room temperature.

[0040] In the embodiment, the cermet composite barrier layer powder is mixed by refractory metal powder and ceramic powder, and a cermet composite phase is formed after hot-pressing sintering. The cermet composite phase as the barrier layer has no serious interface reaction with the skutterudite thermoelectric material and the metal electrode during the welding process, and the element diffusion is slow in the cermet composite phase. Compared with the existing Ti barrier layer, the overall proportion of the brittle reaction layer of the cermet composite phase in the embodiment is reduced, and the reaction layer is also thinned as a whole. The high thermal expansion coefficient of the ceramic in the cermet composite phase adjusts the overall thermal expansion coefficient, and the connection strength is higher. The addition of the ceramic also avoids the problem that the adjustment of the thermal expansion coefficient by other metals will react with the skutterudite, without damaging the overall barrier diffusion effect. Therefore, the connection strength of the cermet composite phase as the diffusion barrier layer in the embodiment is high, the joint resistance is low, the thickness of the reaction layer grows slowly under long-term service, and the thickness of the reaction layer is only increased from 8.5 μm to 15.5 μm after annealing for 135 h, so that good mechanical properties and use performance are maintained. The embodiment can adjust the composition and proportion of the overall barrier layer by selecting different refractory metals and ceramics, and can control the type, thickness and distribution mode of the interface reaction layer by controlling the welding temperature and holding time, so as to control the strength and thermal / electric transport performance of the welded joint.

[0041] Specific embodiment seven: different from the specific embodiment six, the pretreatment process in step one is: sequentially polishing, polishing, cleaning and drying the surface to be welded by using metallographic sandpaper step by step; the cleaning uses ethanol or acetone.

[0042] Specific embodiment eight: different from the specific embodiment six or seven, the thickness of the barrier layer in step one is 20-200 μm.

[0043] Specific embodiment nine: different from one of the specific embodiments six to eight, the metal electrode in step one is Cu, Cu-based alloy, Ni, Ni-based alloy, Fe or Fe-based alloy.

[0044] Specific embodiment ten: different from one of the specific embodiments six to nine, the solder in step two is a copper-based soldering paste.

[0045] Example 1:

[0046] The skutterudite thermoelectric material / electrode high-temperature stable welding method based on the cermet composite barrier layer in the embodiment is carried out according to the following steps:

[0047] I. First, the skutterudite thermoelectric material and the barrier layer are hot-pressed and sintered to obtain a skutterudite with a pre-installed barrier layer; the surface of the barrier layer in the skutterudite with a pre-installed barrier layer is a welding surface, and the welding surfaces of the skutterudite with a pre-installed barrier layer and the metal electrode are pretreated respectively; finally, the pretreated skutterudite with a pre-installed barrier layer and the metal electrode are stored in an inert atmosphere;

[0048] The pretreatment process is: sequentially polishing, polishing, cleaning and drying the welding surface by using metallographic sandpaper step by step; cleaning uses ethanol;

[0049] The preparation method of the skutterudite with a pre-installed barrier layer is: laying a layer of skutterudite powder in a graphite mold, then laying a layer of metal ceramic composite barrier layer powder on the skutterudite powder, and finally hot-pressing and sintering; the process of hot-pressing and sintering is: under vacuum environment, the applied pressure is 40MPa, the temperature is raised to 750℃ at a rate of 10℃ / min and kept for 15min, and then cooled to room temperature at a rate of 20℃ / min;

[0050] The metal ceramic composite barrier layer powder is mixed by refractory metal powder and ceramic powder; the refractory metal powder is Ti and Nb, and the molar percentage of Ti in the metal ceramic composite barrier layer powder is 70%, and the molar percentage of Nb is 20%;

[0051] The thickness of the barrier layer is 200μm;

[0052] The metal electrode is a copper-tungsten electrode with a thickness of 2mm;

[0053] II. Assemble the skutterudite with a pre-installed barrier layer and the metal electrode, the welding surface of the skutterudite with a pre-installed barrier layer faces the welding surface of the metal electrode, and the brazing filler metal is placed between the welding surfaces of the skutterudite with a pre-installed barrier layer and the electrode to obtain a welding part, and finally welding; the process of welding is: in a vacuum brazing furnace with a vacuum degree of 5×10 -3 Pa or less, the temperature is raised to 675℃ at a rate of 10℃ / min and kept for 15min, and then cooled to room temperature at a rate of 10℃ / min; the brazing filler metal is a copper-based brazing filler metal paste.

[0054] This embodiment uses Ti-Nb-TiSi2 as the barrier layer between the skutterudite thermoelectric material and the metal electrode to prevent element diffusion. It can effectively prevent the reaction of Sb element in skutterudite and electrode to form a large amount of intermetallic compound, and the joint has good thermal stability, Figure 1 SEM image of the Ti-Nb-TiSi2 barrier layer / skutterudite thermoelectric material interface obtained in Example 1, Figure 1 It can be seen that the reaction layer of the joint is thin and the element barrier effect is good. Figure 2To implement the metal ceramic composite phase / cobaltite thermoelectric material of example 1, the SEM figure after annealing the welding interface for 135h, the thickness of the reaction layer is only increased from 9.5μm to 14.5μm after annealing at the temperature of 550℃ for 135h.

[0055] Example 2:

[0056] The application is based on the high-thermal-stable welding method of metal ceramic composite barrier layer cobaltite thermoelectric material / electrode, which is carried out according to the following steps:

[0057] I. First, the cobaltite powder is hot-pressed and sintered into cobaltite, and the metal ceramic composite barrier layer powder is hot-pressed and sintered into a pre-set barrier layer; then the welding surfaces of the cobaltite, the metal electrode and the two surfaces of the pre-set barrier layer are pretreated; finally, the treated cobaltite, metal electrode and pre-set barrier layer are stored in an inert atmosphere;

[0058] The pretreatment process is: the welding surface is sequentially polished by gradually polishing with metallographic sandpaper, polishing, cleaning and drying; ethanol is used for cleaning;

[0059] The process of hot-pressing and sintering the cobaltite powder into cobaltite is: in a vacuum environment, the pressure applied is 40MPa, the temperature is raised to 750℃ at a rate of 10℃ / min and kept for 15min, and then cooled to room temperature at a rate of 20℃ / min;

[0060] The process of hot-pressing and sintering the metal ceramic composite barrier layer powder into a pre-set barrier layer is: in a vacuum environment, the pressure applied is 40MPa, the temperature is raised to 750℃ at a rate of 10℃ / min and kept for 15min, and then cooled to room temperature at a rate of 20℃ / min;

[0061] The metal ceramic composite barrier layer powder is mixed by refractory metal powder and ceramic powder; the refractory metal powder is Ti and Nb, the mole percentage of Ti in the metal ceramic composite barrier layer powder is 70%, and the mole percentage of Nb is 20%;

[0062] The thickness of the barrier layer is 200μm;

[0063] The metal electrode is a copper-tungsten electrode with a thickness of 2mm;

[0064] II. The pre-set barrier layer is placed between the welding surface of the cobaltite and the welding surface of the metal electrode to obtain a welding piece, and finally welding is carried out; the welding process is: in a vacuum brazing furnace with a vacuum degree of 5×10 -3 Pa or less, a pressure of 5MPa is applied, the temperature is raised to 675℃ at a rate of 10℃ / min and kept for 15min, and then cooled to room temperature at a rate of 10℃ / min; the brazing filler metal is a copper-based brazing filler metal paste;

[0065] In this embodiment, Ti-Nb-TiSi2 is used as a barrier layer between the skutterudite thermoelectric material and the metal electrode to prevent element diffusion. The Sb element in the skutterudite reacts with the electrode to form a large amount of intermetallic compounds, and the joint has good thermal stability, a thin reaction layer, and good element barrier effect. After annealing at 550°C for 135h, the thickness of the reaction layer only increases from 8.5μm to 15.5μm.

Claims

1. A method for high thermal stable welding of skutterudite thermoelectric materials / electrodes based on a cermet composite barrier layer, characterized in that: The high-thermal-stability welding method for skutterudite thermoelectric material / electrode based on metal ceramic composite barrier layer is performed according to the following steps: Firstly, the skutterudite thermoelectric material and the barrier layer are hot-pressed and sintered to obtain the skutterudite with pre-installed barrier layer; the surface of the barrier layer in the skutterudite with pre-installed barrier layer is the welding surface to be welded, and the welding surfaces to be welded of the skutterudite with pre-installed barrier layer and the metal electrode are pretreated respectively; finally, the skutterudite with pre-installed barrier layer and the metal electrode after treatment are stored in an oxygen-free or inert atmosphere; The preparation method of the skutterudite with pre-installed barrier layer is as follows: a layer of skutterudite powder is laid in a graphite mold, then a layer of metal ceramic composite barrier layer powder is laid on the skutterudite powder, and finally hot-pressing and sintering is performed; The hot-pressing and sintering process is as follows: in a vacuum environment, a pressure of 40-70 MPa is applied, the temperature is raised to 650-760 DEG C at a rate of 10-20 DEG C / min and kept for 5-30 min, and then cooled to room temperature at a rate of 20-50 DEG C / min; The metal-ceramic composite barrier layer powder is made of a mixture of refractory metal powder and ceramic powder; the refractory metal powder is one or more of Mo, V, Zr, Nb, Ta, Re, and Ti; the ceramic powder is M x Si y 、M x N y 、M x O y One or more of, wherein M is one or more of Ti, Zr, Mg, Al, K, Ca, Zn, and Mn; the molar percentage of the refractory metal powder in the metal-ceramic composite barrier layer powder is 60%-90%; II. Assembling the pre-interlayer skutterudite and the metal electrode, with the pre-interlayer skutterudite's welding surface facing the metal electrode's welding surface, placing a filler metal between the pre-interlayer skutterudite's welding surface and the electrode's welding surface to obtain a welding piece, and finally welding; the welding process is as follows: heating to 600-700°C at a rate of 10-20°C / min in a vacuum brazing furnace with a vacuum degree of 5x10 -3 In a vacuum brazing furnace with a vacuum degree of 5x10 -4 Pa, heating to 600-700°C at a rate of 10-20°C / min and holding for 5-30 min, and then cooling to room temperature at a rate of 10-50°C / min.

2. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 1, wherein: The pretreatment process in step one is as follows: the welding surface is sequentially polished by metallographic sandpaper, polished, cleaned and dried; ethanol or acetone is used for cleaning.

3. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 1, wherein: The thickness of the barrier layer in step one is 20-200 μm.

4. The metal ceramic composite barrier based skutterudite thermoelectric material / electrode high thermal stable soldering method of claim 1, wherein: The metal electrode in step one is Cu, Cu-based alloy, Ni, Ni-based alloy, Fe or Fe-based alloy.

5. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 1, wherein: The solder in step two is copper-based soldering paste.

6. A method for high thermal stable welding of skutterudite thermoelectric materials / electrodes based on cermet composite barrier layer, characterized by: The high-thermal-stability welding method for skutterudite thermoelectric material / electrode based on metal ceramic composite barrier layer is performed according to the following steps: Firstly, the skutterudite powder is hot-pressed and sintered into skutterudite, and the metal ceramic composite barrier layer powder is hot-pressed and sintered into pre-installed barrier layer; then the welding surfaces to be welded of the skutterudite, the metal electrode and the two surfaces of the pre-installed barrier layer are pretreated; finally, the skutterudite, the metal electrode and the pre-installed barrier layer after treatment are stored in an oxygen-free or inert atmosphere; The process of hot-pressing and sintering the skutterudite powder into skutterudite is as follows: in a vacuum environment, a pressure of 40-70 MPa is applied, the temperature is raised to 650-760 DEG C at a rate of 10-20 DEG C / min and kept for 5-30 min, and then cooled to room temperature at a rate of 20-50 DEG C / min; The process of hot-pressing and sintering the metal ceramic composite barrier layer powder into pre-installed barrier layer is as follows: in a vacuum environment, a pressure of 40-70 MPa is applied, the temperature is raised to 650-760 DEG C at a rate of 10-20 DEG C / min and kept for 5-30 min, and then cooled to room temperature at a rate of 20-50 DEG C / min; The cermet composite barrier layer powder is mixed by refractory metal powder and ceramic powder; the refractory metal powder is one or more of Mo, V, Zr, Nb, Ta, Re and Ti; the ceramic powder is one or more of Si x Si y , M x N y , M x O y , wherein M is one or more of Ti, Zr, Mg, Al, K, Ca, Zn and Mn; the mole percentage of the refractory metal powder in the cermet composite barrier layer powder is 60%-90%. Secondly, the pre-installed barrier layer is placed between the welding surfaces to be welded of the skutterudite and the metal electrode to obtain a welding piece, and finally welding is performed; The welding process is: in the vacuum degree is 5 × 10 -3 In the vacuum brazing furnace with the vacuum degree below 10 Pa, the pressure of 5-20 MPa is applied, the temperature is increased to 600-700 DEG C at the rate of 10-20 DEG C / min and kept for 5-30 min, and then decreased to room temperature at the rate of 10-50 DEG C / min.

7. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 6, wherein: The pretreatment process in step one is as follows: the welding surface is sequentially polished by metallographic sandpaper, polished, cleaned and dried; ethanol or acetone is used for cleaning.

8. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 6, wherein: The thickness of the barrier layer in step one is 20-200 μm.

9. The cermet composite barrier based skutterudite thermoelectric material / electrode high thermal stability soldering method of claim 6, wherein: The metal electrode in step one is Cu, Cu-based alloy, Ni, Ni-based alloy, Fe or Fe-based alloy.

10. The metal ceramic composite barrier based skutterudite thermoelectric material / electrode high thermal stable soldering method of claim 6, wherein: The solder in step two is copper-based soldering paste.

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