CN109930186B - Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating - Google Patents
Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating Download PDFInfo
- Publication number
- CN109930186B CN109930186B CN201711367583.1A CN201711367583A CN109930186B CN 109930186 B CN109930186 B CN 109930186B CN 201711367583 A CN201711367583 A CN 201711367583A CN 109930186 B CN109930186 B CN 109930186B
- Authority
- CN
- China
- Prior art keywords
- layer
- nickel
- skutterudite
- aluminum
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The invention relates to an Al-Ni-Al composite coating on the surface of a skutterudite-based thermoelectric material, which comprises a first Al layer, a Ni layer and a second Al layer which are sequentially formed on the skutterudite-based thermoelectric material. The composite coating prevents the substrate from being further oxidized, and the ordered intermetallic aluminum nickel compound forms a fine crystal structure, so that the compactness of the composite coating can effectively prevent Sb and oxygen from passing through, and the protection of the surface of a skutterudite material in a skutterudite thermoelectric device can be met.
Description
Technical Field
The invention relates to the field of thermoelectric power generation material protection, in particular to the field of Skutterudite (SKD) thermoelectric material surface protection, and specifically relates to an aluminum-nickel Al-Ni-Al composite coating prepared on the surface of an SKD thermoelectric material.
Background
The thermoelectric material is a functional material that directly converts thermal energy and electric energy into each other, and is realized by utilizing the Seebeck (Seebeck) effect and Peltier (Peltier) effect of a semiconductor material. The thermoelectric power generation device has the advantages of small volume, light weight and no mechanical transmission part. The method has wide application prospect in various aspects such as aerospace power supplies, waste heat recovery power generation, thermoelectric refrigerators, superconducting electronic instruments and the like. The thermoelectric power supply has been applied in aerospace, and how to break through the application barrier of the thermoelectric material and further expand the application range is a hot point of research.
The performance of thermoelectric materials is generally measured by a dimensionless figure of merit, ZT, a larger value representing a better thermoelectric performance of the material. While
(in the formula, α, k, ρ represent the Seebeck coefficient, thermal conductivity, and electrical resistivity of the thermoelectric material, respectively). Various thermoelectric materials have their typical performance characteristics, such as: the Half-Heusler compound is a cubic MgAgAs type structure, and is characterized by having higher electric conductivity and Seebeck coefficient at room temperature, but has the defect of high thermal conductivity, and the thermal conductivity is reduced by adopting a multi-element alloying or replacement method generally; skutterudite structural materials employ a theoretical model of "electronic crystal-phonon glass" (i.e., high performance thermoelectric materials should have crystal-like electrical conductivity and glass-like thermal conductivity). The thermoelectric performance of the material can be obviously improved by adopting a filling mode (1996, B.S. Sales et al propose to fill rare earth atoms in lattice holes of the skutterudite compound) [ Phys.Rev.B 56(1997) 1508-1511-]Maintains a high Seebeck coefficient and can have extremely high electrical conductivity, and the ZT value of the CoSb 3-based thermoelectric material filled compositely is as high as 1.7-2.0[ Journal of Materials Research 26(2011) 1745-; acta materiala 63(2014)30-43]。
When various thermoelectric materials are in service, oxidation and sublimation of hot-end material elements occur, such as: ge in SiGe material, Te in PbTe, and Sb in skutterudite. Among them, the CoSb 3-based skutterudite material is expected to be the most commercially valuable thermoelectric material due to its advantages in terms of performance, price, safety, and the like. The working temperature of the skutterudite at the high-temperature end of the material can reach about 570 ℃, and the vapor pressure of Sb is very high at the temperature, compared with elements such as Fe, Co and the like which are 12 orders of magnitude higher (In-ternet version 87 (2007)), Sb sublimation can lead to the deterioration of the performance of the material. The Energy conversion and Mnement 47(2009),174-200 use a thermal endurance experiment method to study the service behavior of the skutterudite thermoelectric power generation device in an argon atmosphere, and the study shows that when the device is at a high temperature end 973K and a low temperature end 300K for about 3600 hours, the skutterudite thermoelectric device causes the performance of the thermoelectric material to be reduced due to continuous sublimation of Sb at the high temperature end, and the interface contact resistance is increased due to thermal diffusion of the material and the electrode, so that the total output power of the skutterudite device is reduced by about 70%. The problem of easy Oxidation and low thermal stability of the skutterudite material [ Oxidation of Metals74(2010) 113-124; journal of Alloys & Compounds 505(2010) L6-L9 ]. In addition, under the periodic thermal cycle environment, the SKD thermoelectric material can generate phenomena such as element enrichment and element deletion at the grain boundary, so that the microstructure and chemical composition of the material change, and the material performance is deteriorated.
Due to the limitation of the factors, the application of the skutterudite thermoelectric material faces huge challenges, and the volatilization and oxidization problems of the thermoelectric material Sb at the high temperature end are technical problems to be broken through in the industrial application of the thermoelectric material. One effective solution is to coat a protective layer which is resistant to oxidation and Sb sublimation and diffusion on the surface of the material.
The metal coating can inhibit sublimation of elements in the thermoelectric material [ NASA Tech Briefs, September2007,5-6 ]. H.H.Saber, M.S.El-Genk et al [ Energy Conversion and Management48(2007) 555-; energy Conversion and Management,47(2006) 174-; energy Conversion and Management48(2007)1383-1400(2007) ] is encapsulated with molybdenum, tantalum, titanium and vanadium coatings, and provides a solution for SKD-based thermoelectric materials to inhibit Sb dissipation. Sakamoto et al use a continuous metal foil to coat the surface of a skutterudite material with a metal to inhibit sublimation of Sb [ Date of Patent: jan.27(2009)2009 ]. Liu and the like adopt an electrochemical method to prepare a self-sealing end controllable growth Pt single-layer film, and realize a wet atomic layer deposition technology of the Pt film. [ Science,338(2012), 1327-.
The use of glass as a self-healing coating material was proposed as early as the first patent relating to the oxidation protection of Carbon materials in 1934 National Carbon co. Zawadzka et al encapsulate CoSb3 with an enamel coating that protects CoSb3At 873K it is a good diffusion barrier for oxygen, but a small amount of Sb is volatilized at the interface and pores are present. [ AIP Conference Proceedings 1449(2012), 231-.]。
Godlewska et al applied pulse magnetron sputtering method to CoSb3The surface is deposited with a Cr-5Si thin film layer [ oxidized Met74(2010) 205-213).]Thereby protecting the material from aging during elevated temperatures. However, the results show that the oxide formation is thick when the 873K is exposed in the air for 80h, and the protection effect is not achieved.
ZAWADZKA et al prepared polymer metal hybrid coatings to protect CoSb3Skutterudite, [ Ceramic Materials,62(2010) 490-.]The single-layer coating with Al as a filler has no protective effect, and the double-layer coating has slight protective effect, but the cyclic oxidation is easy to peel off. A two-layer coating with Cr as filler can significantly inhibit the sublimation of Sb up to 873K, but cannot prevent the permeation of oxygen into its interior, with the coating failing altogether at 973K.
Dong et al use composite glass materials to protect thermoelectric materials and prevent SKD materials from oxidizing in air at high temperatures. 923K aging test a small amount of Sb is detected in the composite coating. Sublimation of Sb severely limits the performance of skutterudite materials. Intra.39 (2013) 4551-4557.
The glass coating has excellent covering property, and CoSb can be prepared3The oxidation resistance of the substrate is improved to 600 ℃. The glass coating/CoSb is ensured at 600 ℃ due to the higher thermodynamic stability of the oxides present in the coating compared to antimony and/or cobalt oxides3The durability of the system, but the mismatch of thermal expansion coefficient between the glass coating and the skutterudite matrix, the generation of cracks and the provision of new oxygen channels. [ Materials and Design 119(2017) 65-75]。
For the thermoelectric material, the thermoelectric material is prevented from being influenced by external moisture, oxygen and corrosive substances, and the performance of the thermoelectric material is prevented from being reduced due to sublimation of elements. There are generally many ways to coat the protective coating: such as flame spraying, plasma spraying, electric arc spraying and the like, although the methods are widely applied, the prepared coating is generally poor in compactness, the working shape has certain requirements (not applicable to the spraying of the surface with a complex shape), the energy consumption is large, the equipment is complex, and the cost is high.
Patent CN1375576A adopts a specific heat source to heat a metal member to be treated, and utilizes the heat of the member itself to make the special porcelain glaze material automatically melt, wet and flow, and produce dense combination with the substrate of the member to form a glass coating. But the method is difficult to be uniformly coated, and the quality of the coating is difficult to ensure when the size of the sample is small. In addition, the heat treatment curing temperature is difficult to control, the skutterudite material is unstable due to too high temperature, and the adhesive force of the glass glaze layer is insufficient due to too low temperature.
For CoSb3The problem of high temperature volatilization of Sb and oxidation of the material in skutterudite materials, patent application No. 200910055439.3, proposes the use of a physicochemical process in CoSb3The surface of the skutterudite material forms a metal and oxide multilayer coating, thereby achieving the double effects of preventing Sb volatilization and inhibiting material oxidation at high temperature and improving CoSb3The durability and reliability of use of the skutterudite material and its devices. However, the method has the disadvantages of complex process, high cost and insufficient oxidation resistance.
Patent CN103146301A discloses a composite coating of organosilane-modified silica sol and glass powder, which can prevent volatilization of elements and oxidation of materials in thermoelectric materials and devices, has good chemical stability, and is suitable for being used as a protective coating of thermoelectric material substrates. However, the difference in thermal expansion coefficient between the composite coating and the thermoelectric base material may cause thermal stress and strain during use, which may result in generation of defects such as microcracks in the coating, and may cause migration of easily sublimable elements such as Sb between the base thermoelectric material and the glass phase.
Patent CN104890325A adopts an inner layer of ceramic composite coating and an outer layer of porous glass coating. The composite material has good compatibility with a thermoelectric material matrix and good bonding strength, and can effectively insulate heat and prevent the volatilization of matrix elements. However, the SKD thermoelectric material is concentrated on the aspect of recycling waste heat in the middle temperature section of automobile exhaust and industry and the like, the waste heat is often related to annular and other special-shaped SKD thermoelectric materials for efficient utilization, and the mode of coating a coating with uniform thickness and a protective effect on the special-shaped thermoelectric materials has certain difficulty.
U.S. Pat. No. 4, 9065014, 2 discloses the deposition and sintering of Bi0.5Sb1.5Te3Preparation of Al2O3Coating layer, Al2O3-Cu-Al2O3Coatings, Ag coatings and the like have oxidation resistance, but the preparation process is relatively complex and the cost is high.
Therefore, the art needs to search for a preparation technology of an anti-oxidation and anti-corrosion coating which is more suitable for the high-temperature end and the low-temperature end of the thermoelectric material.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide an Al-Ni-Al composite coating of a skutterudite thermoelectric material, which can eliminate or reduce the phenomenon of thermoelectric device performance reduction caused by the oxidation of the thermoelectric material in a thermoelectric device to the maximum extent, has relatively simple preparation method and low price, and can be used for thermoelectric materials (such as CoSb) with complex shape and structure3A base thermoelectric material) surface, and a uniform and dense protective coating which prevents Sb from dissipating and is resistant to oxidation.
Here, in one aspect, the present invention provides a composite coating layer including a first Al layer, a Ni layer, and a second Al layer sequentially formed on a skutterudite-based thermoelectric material.
The composite coating can generate a compact Al-Ni oxide layer at high temperature, prevents a substrate from being further oxidized, has a fine crystal structure formed by ordered intermetallic aluminum nickel oxides, can effectively prevent Sb and oxygen from passing through due to compactness, can meet the requirement of protecting the surface of a skutterudite material in a skutterudite thermoelectric device, is particularly suitable for an antioxidant protective coating on the surface of a SKD thermoelectric material with a relatively complex shape, has important significance for engineering preparation of an aluminum nickel composite coating on the outer surface of the SKD thermoelectric material with the complex shape required for efficiently utilizing waste heat, and has important significance for prolonging the service life and reducing the production cost of the SKD thermoelectric device in practice. According to the invention, the first Al layer, the Ni layer and the second Al layer are sequentially formed on the surface of the substrate, so that oxygen can be prevented from entering, and the nickel coating can be prevented from entering the substrate to cause the change of chemical composition specific gravity and the performance reduction.
In the present invention, the Al-Ni-Al coating layer contains an Al-Ni mixed phase (i.e., an Al-Ni oxide layer). Affected by high temperature and oxidation, the mixed phase including Al2O3NiO, NiAl or Ni3Al. wherein the oxide layer is mainly located between Al-Ni layers on the outer layer of the composite coating, and the aluminum nickel compound is located between Al-Ni layers.
Preferably, the thickness of the composite coating is 45-80 μm.
Preferably, the thickness of the first Al layer is 25-40 μm, the thickness of the Ni layer is 10-20 μm, and the thickness of the second Al layer is 10-20 μm.
In another aspect, the present invention provides a method for preparing the above composite coating layer, in which a first Al layer, a Ni layer, and a second Al layer are sequentially formed on a skutterudite-based thermoelectric material as a base by an electroplating method.
The invention adopts an electroplating method, so that the surface of the obtained plating layer is compact and uniform, and the bonding force with the matrix is good; the thickness of the coating is controllable, no special requirements are particularly required for the shape and size of a base material, the aluminum coating can be coated on large-size complex structural shapes (such as square and cylindrical shapes), and the preparation of the aluminum coating can be realized on the surfaces of annular and other special-shaped thermoelectric devices which can utilize residual heat and waste heat to the maximum extent. In addition, the method can be operated in a near room temperature environment, has a simple process, and is a good basis for industrially preparing SKD surface protective aluminum nickel and related aluminum nickel compound composite coatings.
Preferably, the method comprises:
putting the substrate into a first aluminum plating liquid for electroplating for 45-55 minutes to form a first Al layer on the surface of the substrate, wherein the electroplating technological parameters of the first Al layer are as follows: the substrate is used as a cathode, a pure aluminum material is used as an anode, the temperature is 55-57 ℃, and the current isThe density is 15 to 20mA/cm2；
Putting the substrate with the first Al layer into a nickel plating solution for electroplating for 30-40 minutes, and forming a Ni layer on the surface of the first Al layer, wherein the electroplating technological parameters of the Ni layer are as follows: the substrate with the first Al layer is used as a cathode, the Ti alloy material is used as an anode, the temperature is 35-40 ℃, and the current density is 10-15 mA/cm2；
Placing the substrate with the first Al layer and the Ni layer into a second aluminum plating liquid for electroplating for 25-30 minutes, and forming a second Al layer on the surface of the Ni layer, wherein the electroplating technological parameters of the second Al layer are as follows: the substrate with the first Al layer and the Ni layer is used as a cathode, a pure aluminum material is used as an anode, the temperature is 55-57 ℃, and the current density is 8-15 mA/cm2。
In the invention, the first aluminum plating solution and/or the second aluminum plating solution can be obtained by fully mixing and dissolving an aluminum source and an organic salt in a dry environment under the protection of inert gas to obtain an ionic liquid, and mixing the ionic liquid with a solvent A, wherein the molar ratio of the aluminum source to the organic salt is (1-2): (2-5), wherein the volume ratio of the ionic liquid to the solvent A is (2-4): (1-1.5).
Preferably, the aluminum source is AlCl3、AlCl4 -、Al2Cl7 -At least one of; the organic salt is at least one of chlorinated 1-butyl-3-methylimidazole, chlorinated 1-ethyl-3-methylimidazole and 1 carboxyl-3-methylimidazole chloride salt; the solvent A is at least one of benzene, toluene and xylene.
In the present invention, the nickel plating solution can be obtained by mixing a nickel source, a buffer, and a solvent B.
Preferably, the concentration of the nickel source in the nickel plating solution is 200-400 g/L, and the concentration of the buffering agent in the nickel plating solution is 25-40 g/L.
Preferably, the nickel source is at least one of nickel sulfamate, nickel citrate, nickel fluoborate and nickel chloride; the buffer is at least one of boric acid, hydrochloric acid, phosphoric acid and acetic acid; the solvent B is water.
Preferably, the substrate is pretreated. In one example, the pretreatment may include, for example, sanding followed by ultrasonic cleaning, degreaser degreasing, acid roughening, and the like.
In another aspect, the invention also provides a skutterudite thermoelectric device with the composite coating.
Drawings
FIG. 1 is a schematic cross-sectional view of an Al-Ni-Al composite coating on a skutterudite substrate;
FIG. 2 is a cross-sectional SEM micrograph of example 2;
FIG. 3 is an SEM micrograph of the surface of the coating of example 2;
FIG. 4 is an SEM surface scan energy spectrum of the coating surface of example 2;
FIG. 5 is a graph of the mass loss per unit area of the 600 ℃ weathering test of example 2 and an uncoated substrate;
FIG. 6 is a graph of ZT value as a function of temperature after 20 days of 600 ℃ aging test for example 2 and an uncoated substrate.
Detailed Description
The present invention is further described below in conjunction with the following embodiments, which are intended to illustrate and not to limit the present invention.
The invention relates to an Al-Ni-Al composite coating on the surface of a skutterudite-based (SKD) thermoelectric material. According to the invention, the first Al layer, the Ni layer and the second Al layer (as shown in figure 1) are sequentially formed on the surface of the substrate, and the Al-Ni composite anti-oxidation protective layer of the SKD thermoelectric material is prepared, so that the method has great potential in the aspect of anti-oxidation protection of the special skutterudite-based thermoelectric material with complex size, shape and structure.
In one embodiment of the present invention, the composite coating is prepared using an electroplating process. The method is carried out at the condition of near room temperature, does not need special atmosphere, has the advantages of simple operation process, low energy consumption and the like, can meet the requirement of the skutterudite-based thermoelectric material surface protection composite coating, and has great significance in the engineering preparation of the annular and other special-shaped SKD thermoelectric material surface protection coatings. The method for preparing the Al-Ni-Al composite protective layer (coating) on the skutterudite surface by adopting the electroplating mode can become a basis for realizing the preparation of the aluminum-nickel compound coating on the surface of the SKD material. The method for electroplating the aluminum-nickel composite layer on the SKD material has important significance for protecting the SKD thermoelectric material, eliminating or reducing the influence of high-temperature oxidation of the SKD thermoelectric device and prolonging the service life operation of the SKD thermoelectric device.
The method for producing an Al-Ni-Al composite coating according to the present invention will be specifically described below.
Firstly, the substrate is put into a first aluminum plating liquid for electroplating, and a first Al layer (inner Al layer) is formed on the surface of the substrate. Specifically, the time for electroplating the first Al layer can be 45-55 min; the Al electroplating process parameters can be as follows: the substrate is used as a cathode, a pure aluminum material (such as a pure aluminum sheet and a pure aluminum block) is used as an anode, the temperature is 55-57 ℃, and the current density is 15-20 mA/cm2. The electroplating solution can be kept stirred during the electroplating process, and the stirring speed can be 100-200 r/min. Electroplating is carried out at a proper temperature, so that the cathode polarization can be stabilized, and the grain size can be controlled. A certain pre-treatment of the pure aluminium material may be performed. In one example, pure aluminum material is treated separately, for example, with NaOH solution to remove oxide film, degreaser to remove oil, ultrasonic cleaning with deionized water, and the like. In the present invention, the thickness of the first Al layer can be controlled by controlling the time, temperature, current density, and the like of the plating. In the present invention, the thickness of the first Al layer may be 25 to 40 μm. When the thickness of the first Al layer is 25-40 mu m, the first Al layer has the advantages that the thickness allows Ni to enter the Al layer for reaction, and the allowance is reserved to prevent the Ni from entering skutterudite to influence the performance of the first Al layer.
In the present invention, the substrate is made of a skutterudite thermoelectric material (or "skutterudite-based thermoelectric material"). Skutterudite thermoelectric materials include, for example, but are not limited to CoSb3CoSb-doped skutterudite material3Skutterudite compound, CoSb3Base-filled skutterudite compound, doped CoSb3Base-filled skutterudite compound, Ba, In-filled CoSb3、Er(x+x’)FeyNizCo4-x-y-zSb12Skutterudite and Yb0.3Co4Sb12Etc. … the substrate may be pretreated prior to plating, which may include, for example, grinding, followed by ultrasonic cleaning, degreaser degreasing, acid roughening, etc. In one example of the use of a magnetic resonance imaging system,the pretreatment process of the substrate may include: grinding and polishing the cobaltite matrix by using sand paper (such as 800-mesh, 1200-mesh and 5000-mesh metallographic sand paper) according to the mesh number from small to large to prepare a first sample (matrix sample); placing the first sample into water, and ultrasonically cleaning for a period of time (for example, 2min) to obtain a second sample; putting the second sample into an alkaline degreasing agent, and washing for a period of time (for example, 3-4min) to obtain a third sample; after the third sample is subjected to ultrasonic cleaning by water, a fourth sample is obtained by acid cleaning and coarsening; a fifth sample is obtained after the fourth sample is ultrasonically cleaned in water for a period of time (e.g., 2-3 min). Wherein, the alkaline degreasing agent can adopt a mixed solution of 10-15 wt% of a cleaning agent (such as YB-5-A) and water. The pickling solution may be HNO, for example3:HF:H23:1: 6.
The first aluminum plating solution can be obtained by fully mixing and dissolving an aluminum source and an organic salt in a dry environment under the protection of inert gas to obtain an ionic liquid, and mixing the ionic liquid with a solvent A. In the invention, AlCl can be used as the aluminum source3(Anhydrous AlCl)3)、AlCl4 -、Al2Cl7 -Etc.; the organic salt can be 1-butyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole chloride, 1-carboxy-3-methylimidazole chloride salt, etc.; as the solvent A, benzene, toluene, xylene or the like can be used. The molar ratio of the aluminum source to the organic salt can be (1-2): (2-5); the volume ratio of the ionic liquid to the solvent A can be (2-4): (1-1.5). The molar ratio of the aluminum source to the organic salt is (1-2): (2-5), the acid condition can be maintained. The inert gas may be argon, helium, or the like. The "dry environment" referred to above refers to an environment of very low moisture content. The aluminum coating has the characteristic performances of oxidation resistance, corrosion resistance and the like, is an excellent surface coating material, can form a compact coating with the thickness of hundreds of micrometers and controllable thickness on the inner surface and the outer surface of a complex shape by adjusting the parameters of the electroplating process, and has unique advantages.
Then, the substrate with the first Al layer is put into a nickel plating solution for electroplating, and a Ni layer is formed on the surface of the first Al layer, namely one side surface of the first Al layer is connected with the substrate, and the other side surface of the first Al layer is connected with the Ni layerAre connected with each other. Specifically, the time for electroplating the Ni layer can be 30-40 minutes; the electroplating process parameters of the Ni layer can be as follows: the substrate with the first Al layer is used as a cathode, a Ti alloy material (such as a Ti alloy net) is used as an anode, the temperature is 35-40 ℃, and the current density is 10-15 mA/cm2. The electroplating solution can be kept stirred during the electroplating process, and the stirring speed can be 100-200 r/min. The thickness of the Ni layer can be controlled by controlling the time, temperature, current density, etc. of the plating. In the present invention, the Ni layer may have a thickness of 10 to 20 μm. When the thickness of the Ni layer is 10-20 μm, the method has the advantage of producing the aluminum nickel compound to the maximum extent.
The nickel plating solution can be obtained by mixing a nickel source, a buffer and a solvent B. In the invention, the nickel source can adopt nickel sulfamate, nickel citrate, nickel fluoborate or nickel chloride and the like; the buffering agent can be boric acid, hydrochloric acid, phosphoric acid or acetic acid; water can be used as solvent B. The molar ratio of the nickel source to the buffer can be (8-12): (1-2). The concentration of the nickel source in the nickel plating solution can be 200-400 g/L; the concentration of the buffering agent in the nickel plating solution can be 25-40 g/L. When the concentration of the nickel source in the nickel plating solution is 200-400 g/L, the method has the advantages of keeping sufficient supply of the Ni source and uniform distribution of the concentration of the plating solution.
And then, putting the substrate with the first Al layer and the Ni layer into a second aluminum plating liquid for electroplating, and forming a second Al layer (an outer Al layer) on the surface of the Ni layer, wherein the Ni layer is positioned between the first Al layer and the second Al layer, and the Al layer, the Ni layer and the Al layer are respectively arranged on the substrate from inside to outside. Specifically, the time for electroplating the second Al layer can be 25-30 minutes; the electroplating process parameters of the second Al layer can be as follows: the substrate with the first Al layer and the Ni layer is used as a cathode, the pure aluminum material is used as an anode, the temperature is 55-57 ℃, and the current density is 8-15 mA/cm2. The electroplating solution can be kept stirred during the electroplating process, and the stirring speed can be 100-200 r/min. The thickness of the second Al layer can be controlled by controlling the time, temperature, current density, etc. of the plating. In the present invention, the thickness of the second Al layer may be 10 to 20 μm. When the thickness of the second Al layer is 10-20 μm, the second Al layer has the advantages of oxidation resistance and enough thickness to form an aluminum nickel compound with the Ni layer.
The second aluminum plating solution can be prepared by mixing an aluminum source and an organic solventAnd fully mixing and dissolving the salt in a dry environment under the protection of inert gas to obtain ionic liquid, and mixing the ionic liquid with the solvent A to obtain the compound. Wherein AlCl can be adopted as an aluminum source3(Anhydrous AlCl)3)、AlCl4 -、Al2Cl7 -Etc.; the organic salt can be 1-butyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole chloride or 1-carboxy-3-methylimidazole chloride salt; as the solvent A, benzene, toluene, xylene or the like can be used. The molar ratio of the aluminum source to the organic salt can be (1-2): (2-5); the volume ratio of the ionic liquid to the solvent A can be (2-4): (1-1.5). In the invention, the second aluminum plating solution may be the same as the first aluminum plating solution, or the first aluminum plating solution and the second aluminum plating solution may adopt different aluminum plating solutions.
According to the method, the Al-Ni-Al composite coating on the surface of the skutterudite thermoelectric material is obtained. The thickness of the composite coating is 45-80 μm. The composite coating obtained above may be subjected to certain post-treatment. In one example, the obtained skutterudite thermoelectric material surface Al-Ni-Al composite coating is cleaned by absolute ethyl alcohol and dried to obtain a product.
The Al-Ni-Al composite coating on the surface of the skutterudite thermoelectric material can generate a compact Al-Ni oxide layer at high temperature, the substrate is prevented from being further oxidized, the ordered intermetallic aluminum nickel compound forms a fine crystal structure, the compactness can effectively prevent Sb and oxygen from passing through, the protection on the surface of the skutterudite material in a skutterudite thermoelectric device can be met, the Al-Ni composite coating is particularly suitable for an anti-oxidation protective coating on the surface of an SKD thermoelectric material with a relatively complex shape, the Al-Ni composite coating has important significance for the engineering preparation of the Al-Ni composite coating on the outer surface of the SKD thermoelectric material with the complex shape required for efficiently utilizing the residual waste heat, and the Al-Ni composite coating has important significance for the practical application of the SKD thermoelectric device, prolonging the service life and reducing the production cost.
The invention has the advantages that:
according to the invention, the first Al layer, the Ni layer and the second Al layer are sequentially formed on the surface of the substrate, so that the aluminum-nickel composite coating can be tightly combined on the substrate by utilizing the physicochemical characteristic of Ni, the oxidation resistance of the aluminum-nickel oxide and the aluminum-nickel compound is enhanced, and micro cracks of single-layer aluminum caused by mismatching of thermal expansion coefficients are avoided. The surface of the plating layer obtained by the method is compact and uniform, and the bonding force with the substrate is good; the thickness of the coating is controllable, no special requirements are particularly required for the shape and the size of a base material, the aluminum coating can be coated on the large-size complex structure shape, and the preparation of the aluminum coating is realized on the surfaces of annular and other special-shaped thermoelectric devices which can utilize the residual heat and the waste heat to the maximum extent;
the method can be operated in a near room temperature environment, has a simple process, and is a good foundation for industrially preparing SKD surface protective aluminum-nickel and related aluminum-nickel compound coatings;
the method for electroplating the aluminum-nickel composite layer on the SKD material has important significance for protecting the SKD thermoelectric material, eliminating or reducing the influence of high-temperature oxidation of the SKD thermoelectric device and prolonging the service life operation of the SKD thermoelectric device.
The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.
Example 1
The Al-Ni-Al composite coating is prepared on the surface of a cylindrical skutterudite material by electroplating, and the specific operation process is as follows:
selecting a three-neck flask with a proper size, cleaning the three-neck flask with absolute ethyl alcohol, and drying the three-neck flask in a drying box for later use;
taking analytically pure anhydrous AlCl3And uniformly stirring and mixing the mixture with chlorinated 1-butyl-3-methylimidazole (BMIC) in a molar ratio of 2:1 in a dry environment to obtain the ionic liquid. Pouring the solution into a clean and dried three-neck flask, pouring analytically pure benzene with the volume approximately equal to that of the ionic liquid into the three-neck flask, and uniformly stirring by using magnetic force to obtain a plating solution;
a high-purity aluminum block is selected as an anode for electroplating. Respectively removing an oxide layer film by using NaOH solution, removing oil by using a deoiling agent, ultrasonically cleaning by using deionized water and the like, and immediately transferring into a standby three-mouth bottle for electroplating after cleaning and drying;
taking P-type skutterudite with phi of 5.68mm and h of 19.77mm as a plating object, polishing a substrate step by step from coarse to fine by using abrasive paper, then performing ultrasonic cleaning by using deionized water, deoiling by using a deoiling agent and roughening by using acid liquor, cleaning, drying and immediately transferring into a three-neck bottle for electroplating;
fully immersing an anode aluminum block and an SKD (skutterudite) substrate into the electroplating solution, and stirring the ionic liquid by using magnetic force at a stirring speed of 100-200 r/min. A constant current method is adopted at the temperature of 55 ℃, and the current density is 15-16 mA/cm2；
And (5) after electroplating for about 50min, cutting off the power to obtain a primary product. Ultrasonically cleaning the product with absolute ethyl alcohol and drying to obtain an initial product;
a clean beaker was taken, a small amount of deionized water (about 80ml) was added to the beaker, and 120g of nickel sulfamate and 14g of boric acid were weighed into the beaker. Adding deionized water to 400ml of scale marks, and stirring and fully dissolving to obtain uniform plating solution;
titanium alloy is selected as an anode, and the primary product is a cathode. Stirring in a water bath at 45 ℃ at a stirring speed of 100-200 r/min. The current density is 10mA/cm2And electroplating for 30 minutes. Cleaning in deionized water to obtain an intermediate product;
taking the intermediate product as a cathode and pure aluminum as an anode in the aluminum plating solution, wherein the stirring speed is 100-200 r/min. Adopting a constant current method at 55 ℃ and the current density is 10mA/cm2Electroplating for 30 min. And cleaning the obtained product in absolute ethyl alcohol. And obtaining a final product.
The SKD material prepared by the embodiment has compact and smooth surface coating and good bonding force.
Example 2
Preparing an Al-Ni-Al composite coating on the surface of cuboid SKD (skutterudite) by electroplating, which comprises the following specific operations:
selecting a three-neck flask with a proper size, cleaning the three-neck flask with absolute ethyl alcohol, and drying the three-neck flask in a drying box for later use;
taking analytically pure anhydrous AlCl3And uniformly stirring and mixing the mixture with chlorinated 1-butyl-3-methylimidazole (BMIC) in a molar ratio of 2:1 in a dry environment to obtain the ionic liquid. Pouring the solution into a clean and dried three-neck flask, pouring analytically pure benzene with the volume approximately equal to that of the ionic liquid into the three-neck flask, and uniformly stirring by using magnetic force to obtain a plating solution;
a high-purity aluminum block is selected as an anode for electroplating. Respectively removing an oxide layer film by using NaOH solution, removing oil by using a deoiling agent, ultrasonically cleaning by using deionized water and the like, and immediately transferring into a standby three-mouth bottle for electroplating after cleaning and drying;
taking N-type skutterudite with the length, width and height of 11.73mm, 3.81mm and 3.89mm as a plating object, polishing a substrate step by step from coarse to fine by using abrasive paper, then performing ultrasonic cleaning by using deionized water, deoiling by using a deoiling agent and roughening by using acid liquor, cleaning, drying and immediately transferring into a three-neck bottle for electroplating;
fully immersing an anode aluminum block and an SKD (skutterudite) substrate into the electroplating solution, and stirring the ionic liquid by using magnetic force at a stirring speed of 100-200 r/min. A constant current method is adopted at the temperature of 55 ℃, and the current density is 15-16 mA/cm2；
After electroplating for about 50min, powering off, cleaning the obtained product in absolute ethyl alcohol and drying to obtain a primary product;
a clean beaker was taken, a small amount of deionized water (about 80ml) was added to the beaker, and 120g of nickel sulfamate and 14g of boric acid were weighed into the beaker. Adding deionized water to 400ml of scale marks, and stirring and fully dissolving to obtain uniform plating solution;
titanium alloy is selected as an anode, and the primary product is a cathode. Stirring in a water bath at 45 ℃ at a stirring speed of 100-200 r/min. The current density is 10mA/cm2And electroplating for 30 minutes. Cleaning in deionized water to obtain an intermediate product;
taking the intermediate product as a cathode and pure aluminum as an anode in the aluminum plating solution, wherein the stirring speed is 100-200 r/min. Adopting a constant current method at 55 ℃ and the current density is 10mA/cm2Electroplating for 30 min. And cleaning the obtained product in absolute ethyl alcohol. And obtaining a final product.
The SKD material prepared by the embodiment has compact surface coating structure and no obvious fluctuation phenomenon.
FIG. 2 is a cross-sectional SEM micrograph of example 2. As can be seen from fig. 2, the bonding between the plating layers and between the plating layer and the substrate was good. FIG. 3 is an SEM micrograph of the surface of the coating of example 2. As can be seen from FIG. 3, the SKD material prepared by the example has a dense surface coating structure and no obvious fluctuation. FIG. 4 is an SEM surface scan energy spectrum of the coating surface of example 2. As can be seen from fig. 4, the plating purity was high.
Repeated experiments are carried out for a plurality of times by adopting the invention, and the results show that: the composite coating prepared on the surface of SKD (skutterudite) has compact structure, uniform and controllable thickness and good combination with a substrate. The method is further proved to have good repeatability by combining the simplicity of operation, can meet the industrial requirement and has wide market prospect.
The P-type skutterudite protected by the coating and the P-type skutterudite in the example 2 are aged in an aerobic environment at 600 ℃ to obtain the comparison of the performances of the substrate/Al/Ni/Al and the substrate without the coating, for example, the coating shows the capability of preventing Sb from dissipating as shown in figure 5, for example, the coating shows the protection of the performances of the skutterudite material as shown in figure 6, and the higher the ZT value is, the better the performances are.
Claims (8)
1. The composite coating is characterized by comprising a first Al layer, a Ni layer and a second Al layer which are sequentially formed on a skutterudite-based thermoelectric material, wherein the thickness of the composite coating is 45-80 mu m, the thickness of the first Al layer is 25-40 mu m, the thickness of the Ni layer is 10-20 mu m, and the thickness of the second Al layer is 10-20 mu m.
2. A method for producing the composite coating layer according to claim 1, characterized in that a first Al layer, a Ni layer, and a second Al layer are formed in this order on a skutterudite-based thermoelectric material as a base by an electroplating method.
3. The method of claim 2, comprising:
putting the substrate into a first aluminum plating liquid for electroplating for 45-55 minutesForming a first Al layer on the surface of the substrate, wherein the electroplating technological parameters of the first Al layer are as follows: the substrate is used as a cathode, a pure aluminum material is used as an anode, the temperature is 55-57 ℃, and the current density is 15-20 mA/cm2；
Putting the substrate with the first Al layer into a nickel plating solution for electroplating for 30-40 minutes, and forming a Ni layer on the surface of the first Al layer, wherein the electroplating technological parameters of the Ni layer are as follows: the substrate with the first Al layer is used as a cathode, the Ti alloy material is used as an anode, the temperature is 35-40 ℃, and the current density is 10-15 mA/cm2；
Placing the substrate with the first Al layer and the Ni layer into a second aluminum plating liquid for electroplating for 25-30 minutes, and forming a second Al layer on the surface of the Ni layer, wherein the electroplating technological parameters of the second Al layer are as follows: the substrate with the first Al layer and the Ni layer is used as a cathode, a pure aluminum material is used as an anode, the temperature is 55-57 ℃, and the current density is 8-15 mA/cm2。
4. The method according to claim 3, wherein the first aluminum plating solution and/or the second aluminum plating solution is obtained by fully mixing and dissolving an aluminum source and an organic salt in a dry environment under the protection of inert gas to obtain an ionic liquid, and mixing the ionic liquid with a solvent A, wherein the molar ratio of the aluminum source to the organic salt is (1-2): (2-5), wherein the volume ratio of the ionic liquid to the solvent A is (2-4): (1-1.5).
5. The method of claim 4, wherein the aluminum source is AlCl3、AlCl4 - 、Al2Cl7 -At least one of; the organic salt is at least one of chlorinated 1-butyl-3-methylimidazole, chlorinated 1-ethyl-3-methylimidazole and 1 carboxyl-3-methylimidazole chloride salt; the solvent A is at least one of benzene, toluene and xylene.
6. The method according to any one of claims 3 to 5, wherein the nickel plating solution is obtained by mixing a nickel source, a buffer and a solvent B, wherein the concentration of the nickel source in the nickel plating solution is 200-400 g/L, and the concentration of the buffer in the nickel plating solution is 25-40 g/L.
7. The method of claim 6, wherein the nickel source is at least one of nickel sulfamate, nickel citrate, nickel fluoborate, nickel chloride; the buffer is at least one of boric acid, hydrochloric acid, phosphoric acid and acetic acid; the solvent B is water.
8. A skutterudite thermoelectric device having the composite coating of claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711367583.1A CN109930186B (en) | 2017-12-18 | 2017-12-18 | Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711367583.1A CN109930186B (en) | 2017-12-18 | 2017-12-18 | Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109930186A CN109930186A (en) | 2019-06-25 |
| CN109930186B true CN109930186B (en) | 2021-03-16 |
Family
ID=66982850
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711367583.1A Active CN109930186B (en) | 2017-12-18 | 2017-12-18 | Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109930186B (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012024120A1 (en) * | 2010-08-20 | 2012-02-23 | Corning Incorporated | P-type skutterudite material and method of making the same |
| CN102514282A (en) * | 2011-12-15 | 2012-06-27 | 济南大学 | Protective coating suitable for CoSb3 base thermoelectric material and preparation method thereof |
| CN102770196A (en) * | 2009-11-11 | 2012-11-07 | 新纳米有限公司 | Porous materials |
| CN104465976A (en) * | 2013-09-22 | 2015-03-25 | 中国科学院上海硅酸盐研究所 | Protected thermoelectric element, thermoelectric device comprising same and forming method thereof |
| CN104890325A (en) * | 2014-03-03 | 2015-09-09 | 中国科学院上海硅酸盐研究所 | Protective coating for thermoelectric material or thermoelectric device |
| JP2017168609A (en) * | 2016-03-16 | 2017-09-21 | 古河機械金属株式会社 | Thermoelectric conversion element, thermoelectric conversion module, and thermoelectric conversion system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110220166A1 (en) * | 2010-03-12 | 2011-09-15 | Ruxandra Vidu | Method of synthesis cobalt antimonide nanoscale structures and device |
-
2017
- 2017-12-18 CN CN201711367583.1A patent/CN109930186B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102770196A (en) * | 2009-11-11 | 2012-11-07 | 新纳米有限公司 | Porous materials |
| WO2012024120A1 (en) * | 2010-08-20 | 2012-02-23 | Corning Incorporated | P-type skutterudite material and method of making the same |
| CN102514282A (en) * | 2011-12-15 | 2012-06-27 | 济南大学 | Protective coating suitable for CoSb3 base thermoelectric material and preparation method thereof |
| CN104465976A (en) * | 2013-09-22 | 2015-03-25 | 中国科学院上海硅酸盐研究所 | Protected thermoelectric element, thermoelectric device comprising same and forming method thereof |
| CN104890325A (en) * | 2014-03-03 | 2015-09-09 | 中国科学院上海硅酸盐研究所 | Protective coating for thermoelectric material or thermoelectric device |
| JP2017168609A (en) * | 2016-03-16 | 2017-09-21 | 古河機械金属株式会社 | Thermoelectric conversion element, thermoelectric conversion module, and thermoelectric conversion system |
Non-Patent Citations (6)
| Title |
|---|
| CoSb3基方钴矿热电材料保护涂层研究进展;包鑫 等;《材料导报》;20190331;第33卷(第3期);784-789 * |
| CoSb3基方钴矿热电材料及其热电性能优化研究;杨帆 等;《材料应用》;20140131(第1期);60-65 * |
| Fabrication and thermal aging behavior of skutterudites with silica-based composite protective coatings;Hongliang Dong et al.;《Journal of Alloys and Compounds》;20120303;第527卷;247-251 * |
| protective coating to suppress degradation of cosb3 thermoelectric at elevated temperatures;E.Godlewska et al.;《material ceramiczne materials》;20100430;第6卷(第4期);490-495 * |
| Protective Properties of Electrochemically Deposited Al-Based Coatings on Yb0.3Co4Sb12 Skutterudite;XIN BAO et al.;《Journal of ELECTRONIC MATERIALS》;20190111;1-9 * |
| 方钴矿热电元件Ni电极和TiSi2阻挡层制备及界面性能研究;师兰芳;《中国科学院大学硕士学位论文集》;20161231;58 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109930186A (en) | 2019-06-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2460182B1 (en) | A coating for thermoelectric materials and a device containing the same | |
| EP2415089B1 (en) | Thermoelectric material coated with a protective layer | |
| EP3046116B1 (en) | Superconductor and method of manufacturing same | |
| US20120097205A1 (en) | Magnesium-silicon composite material and process for producing same, and thermoelectric conversion material, thermoelectric conversion element, and thermoelectric conversion module each comprising or including the composite material | |
| JP2007502536A (en) | New metal strip | |
| JP2012523111A (en) | Thermoelectric module having an insulating substrate | |
| CN104465976B (en) | Shielded thermoelectric element, the thermo-electric device comprising the thermoelectric element and forming method thereof | |
| Xu et al. | A perovskite solar cell textile that works at− 40 to 160° C | |
| CN109930186B (en) | Skutterudite-based thermoelectric material surface Al-Ni-Al composite coating | |
| Piccardo et al. | Metallic interconnects for SOFC: Characterization of their corrosion resistance in hydrogen/water atmosphere and at the operating temperatures of differently coated metallic alloys | |
| Xia et al. | Preparation and structural evolution of Mo/SiOx protective coating on CoSb3-based filled skutterudite thermoelectric material | |
| Nie et al. | Protection coatings for planar solid oxide fuel cell interconnect prepared by plasma spraying | |
| Lv et al. | Effect of spraying power on the microstructure and thermoelectric performance of plasma sprayed higher manganese silicides films | |
| EP2944624A1 (en) | MAX phase materials free of the elements Al and Si | |
| Kim et al. | Free-standing Bi–Sb–Te films derived from thermal annealing of sputter-deposited Sb 2 Te 3/Bi 2 Te 3 multilayer films for thermoelectric applications | |
| JP4876422B2 (en) | Laminated body | |
| US20180112081A1 (en) | Composite thermoelectric material and its manufacturing method | |
| Qiu et al. | Antimony telluride thin films electrodeposited in an alkaline electrolyte | |
| CN102514282A (en) | Protective coating suitable for CoSb3 base thermoelectric material and preparation method thereof | |
| CN105349936A (en) | Metal tungsten surface WAl4-AlN-Al2O3 high-temperature insulation coating and preparation method thereof | |
| WO2024060115A1 (en) | Thermoelectric device containing protective layer and manufacturing method therefor | |
| Chen et al. | Atmospheric Plasma-Sprayed La0. 3Sr0. 7TiO3-δ Interconnect for High-Temperature Solid Oxide Fuel Cells | |
| JP5718671B2 (en) | Thermoelectric conversion material and manufacturing method thereof | |
| TWI541382B (en) | A coating for thermoelectric materials and a device containing the same | |
| JPH01221810A (en) | Oxide superconductive mold and its manufacture |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |