Porous SiC preform, Al / SiC composite material and preparation method, and stack shell

Abstract

The porous SiC preform provided in the present application can enhance the bonding force between SiC matrices by selecting a specific inorganic binder, and the provided porous SiC preform can make the prepared Al / SiC composite material have a lower density and higher strength, and has a lower thermal expansion coefficient and a higher thermal conductivity coefficient, and can be used as a fuel cell shell material.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic composite materials, and in particular to a porous SiC preform, an Al / SiC composite material and a preparation method, and a fuel cell stack shell. Background Art

[0002] Fuel cells are one of the primary technologies for new energy vehicles. With the increasing adoption of electrification, fuel cell vehicles are subject to diverse operating environments. Impact damage from ground objects, rainwater splashing, and atmospheric pollution can easily damage the fuel cell stack, necessitating a stack housing to protect it.

[0003] Fuel cell stack casings commonly used in the market are primarily made of metal or resin. Metal materials are primarily aluminum alloy or stainless steel. Aluminum alloy is easy to process but lacks strength, while stainless steel offers strength but suffers from high density and weight. Fuel cell stack casings made of resin also suffer from insufficient strength and easy deformation. Summary of the Invention

[0004] Based on this, the present application provides a porous SiC preform, an Al / SiC composite material, a preparation method, and a fuel cell stack housing. The porous SiC preform provided in the present application enables the prepared Al / SiC composite material to have both low density and high strength, and excellent thermal conductivity.

[0005] In a first aspect of the present application, a porous SiC preform is provided, wherein the porous SiC preform comprises a SiC matrix and an inorganic binder dispersed in the SiC matrix.

[0006] The mass ratio of the inorganic binder to the SiC substrate is (0.02-0.1):1;

[0007] The inorganic binder includes one or more of sodium silicate and lithium silicate.

[0008] In one embodiment, the raw materials for preparing the SiC matrix include SiC powder of a first particle size and SiC powder of a second particle size.

[0009] The particle size ratio of the SiC powder of the first particle size to the SiC powder of the second particle size is ≥2.

[0010] In one embodiment, the SiC substrate has one or more of the following characteristics:

[0011] (1) The particle size of the first particle size SiC powder is 50 μm to 500 μm;

[0012] (2) The particle size of the second particle size SiC powder is 25 μm to 250 μm;

[0013] (3) The total volume ratio of the SiC powder of the first particle size to the total volume of the SiC powder of the second particle size is (0.5-1):1.

[0014] In one embodiment, the porosity of the porous SiC preform is 45% to 75%.

[0015] A second aspect of the present application provides a method for preparing the porous SiC preform according to any embodiment of the first aspect of the present application, comprising the following steps:

[0016] The raw materials for preparing the SiC matrix are mixed with the inorganic binder and the porogen, and after forming and sintering, the porogen is discharged to prepare the porous SiC preform.

[0017] In one embodiment, the sintering process parameters include: a sintering temperature of 600°C to 750°C.

[0018] In a third aspect of the present application, an Al / SiC composite material is provided, comprising the porous SiC preform as described in any embodiment of the first aspect of the present application and an Al phase filling the pores of the porous SiC preform and coating the outer surface of the porous SiC preform.

[0019] In one embodiment, in the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (25% to 55%): (75% to 45%).

[0020] In one embodiment, in the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (40% to 50%): (60% to 50%).

[0021] A fourth aspect of the present application provides a method for preparing the Al / SiC composite material according to any embodiment of the third aspect of the present application, comprising the following steps:

[0022] Aluminum and / or aluminum alloy is heated to be molten, filled into the pores of the porous SiC preform, and coated on the outer surface of the porous SiC preform to form the Al phase, thereby preparing the Al / SiC composite material.

[0023] In one embodiment, the filling method includes vacuum infiltration and / or pressure infiltration.

[0024] Among them, the process parameters of vacuum pressure infiltration include: vacuum degree ≤-95kPa, pressure 3Bar~6Bar.

[0025] In a fifth aspect of the present application, a fuel cell stack shell is provided, comprising the porous SiC preform described in any embodiment of the first aspect of the present application or the Al / SiC composite material described in any embodiment of the third aspect of the present application.

[0026] The porous SiC preform provided in the present application can enhance the bonding force between SiC matrices by selecting a specific inorganic binder, and the provided porous SiC preform can make the prepared Al / SiC composite material have a lower density and higher strength, and has a lower thermal expansion coefficient and a higher thermal conductivity coefficient, and can be used as a fuel cell shell material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of the battery stack housing of this application;

[0028] Figure 2 This is a process flow chart of the Al / SiC composite material preparation method of this application. DETAILED DESCRIPTION

[0029] The following, in conjunction with specific examples, provides a further complete and clear description of the porous SiC preform, Al / SiC composite material, stack housing, and corresponding preparation methods of the present application. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to facilitate a more thorough and comprehensive understanding of the disclosure herein.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0031] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0032] In this application, terms such as "first aspect," "second aspect," "third aspect," "fourth aspect," and "fifth aspect" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," "third," "fourth," and "fifth" serve only as non-exhaustive enumeration and description, and should not constitute a closed-ended limitation on quantity.

[0033] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0035] Unless otherwise specified, the percentage contents mentioned in this application refer to mass percentage for solid-liquid mixture and solid-solid mixture, and refer to volume percentage for liquid-liquid mixture.

[0036] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0037] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control.

[0038] In a first aspect of the present application, a porous SiC preform is provided, wherein the porous SiC preform comprises a SiC matrix and an inorganic binder dispersed in the SiC matrix.

[0039] The mass ratio of the inorganic binder to the SiC substrate is (0.02-0.1):1;

[0040] The inorganic binder includes one or more of sodium silicate and lithium silicate.

[0041] It is understood that the mass ratio of the inorganic binder to the SiC substrate can be selected from any value between (0.02-0.1): 1. Specifically, the mass ratio of the inorganic binder to the SiC substrate includes but is not limited to 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1 or 0.1:1.

[0042] Preferably, the mass ratio of the inorganic binder to the SiC matrix is (0.3-0.6): 1. By adjusting the mass ratio of the inorganic binder to the SiC matrix, it is possible to ensure that the inorganic binder can increase the bonding strength of the porous SiC preform while ensuring that the porous SiC preform has both fluidity and plasticity.

[0043] In one example, the raw materials for preparing the SiC matrix include SiC powder of a first particle size and SiC powder of a second particle size.

[0044] The particle size ratio of the SiC powder of the first particle size to the SiC powder of the second particle size is ≥2.

[0045] In one example, the particle size of the first-size SiC powder is 50 μm to 500 μm. It is understood that the particle size of the first-size SiC powder can be selected from any value between 50 μm and 500 μm. Specifically, the particle size of the first-size SiC powder includes but is not limited to 50 μm, 70 μm, 80 μm, 100 μm, 150 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 300 μm, 400 μm, or 500 μm.

[0046] In one example, the particle size of the second-size SiC powder is 25 μm to 250 μm. Specifically, the particle size of the second-size SiC powder includes but is not limited to 25 μm, 30 μm, 40 μm, 45 μm, 48 μm, 50 μm, 55 μm, 60 μm, 80 μm, 100 μm, 120 μm, 150 μm, 200 μm, or 250 μm.

[0047] In one example, the ratio of the total volume of the SiC powder of the first particle size to the total volume of the SiC powder of the second particle size is (0.5-1):1.

[0048] By selecting SiC powders of different particle sizes, the gaps between the first particle size powders can be filled with the second particle size powders. At the same time, by adjusting the total volume ratio of the first particle size SiC powder to the second particle size SiC powder, it is more conducive to compact filling of the first particle size SiC powder and the second particle size SiC powder, the specific surface area and volume in the porous SiC preform can be adjusted, and the pore distribution in the porous SiC preform can be made more uniform.

[0049] In one example, the porosity of the porous SiC preform is 45% to 75%. Specifically, the porosity of the porous SiC preform includes but is not limited to 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 70% or 75%.

[0050] Preferably, the porosity of the porous SiC preform is 50% to 70%.

[0051] More preferably, the porosity of the porous SiC preform is 50% to 60%. By adjusting the porosity of the porous SiC preform, the volume of other components subsequently filled in the pores of the porous SiC preform can be controlled, which has good adjustability.

[0052] In a second aspect of the present application, there is provided a method for preparing the porous SiC preform according to any example of the first aspect of the present application, comprising the following steps:

[0053] The raw materials for preparing the SiC matrix are mixed with the inorganic binder and the porogen, and after forming and sintering, the porogen is discharged to prepare the porous SiC preform.

[0054] It is understood that the present application does not have any special requirements for the amount of the porogen, and the conventional amount in the art can be referred to. In one example, the porogen uses an organic binder, which includes one or more of methyl cellulose, ethyl cellulose, polyvinyl alcohol, and silicone.

[0055] In one example, the sintering process parameters include a sintering temperature of 600°C to 750°C. By controlling the sintering temperature, the organic binder is expelled, increasing the porosity of the porous SiC preform while preventing the SiC matrix from oxidizing into SiO2, a material with low thermal conductivity, thereby improving the thermal conductivity of the porous SiC preform.

[0056] In one example, the sintering process parameters include: sintering time of 2 to 4 hours, sintering heating rate of 5°C / min, first stage 120°C, holding time of 20 minutes; second stage 600 to 750°C, holding time of 1 to 2 hours.

[0057] In one example, the sintering step is performed under a nitrogen atmosphere.

[0058] In one example, the forming step includes the steps of granulating the blank and drying and dehydrating the blank.

[0059] The method for preparing the porous SiC preform specifically comprises the following steps:

[0060] S10, selecting a first particle size SiC powder and a second particle size SiC powder with a particle size ratio of ≥2 according to a ratio of the total volume of the first particle size SiC powder to the total volume of the second particle size SiC powder of (0.5-1):1; mixing the first particle size SiC powder and the second particle size SiC powder to prepare a SiC matrix;

[0061] S20, adding an inorganic binder and an organic binder to the SiC matrix and mixing them to prepare a SiC blank;

[0062] S30, granulating the SiC blank, drying and dehydrating it, and then placing it into a stack housing mold for compression molding; after compression molding, performing high-temperature sintering at a temperature of 600° C. to 750° C., discharging the organic binder, and preparing a porous SiC preform;

[0063] In a third aspect of the present application, an Al / SiC composite material is provided, comprising the porous SiC preform as described in any embodiment of the first aspect of the present application and an Al phase filling the pores of the porous SiC preform and coating the outer surface of the porous SiC preform.

[0064] The porous SiC preform provided in this application can make the prepared Al / SiC composite material have lower density and higher strength, as well as lower thermal expansion coefficient and higher thermal conductivity, and can be used as a fuel cell shell material.

[0065] In one example, in the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (25% to 55%): (75% to 45%).

[0066] Preferably, in the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (30% to 50%): (70% to 50%).

[0067] More preferably, in the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (40% to 50%): (60% to 50%).

[0068] The volume ratio of the porous SiC preform to the Al phase plays a significant role in improving the strength of the Al / SiC composite, reducing the coefficient of thermal expansion, and enhancing thermal conductivity. A volume ratio of the porous SiC preform to the Al phase of (40% to 50%):(60% to 50%) can result in an Al / SiC composite with higher strength, lower coefficient of thermal expansion, and superior thermal conductivity.

[0069] In a fourth aspect of the present application, there is provided a method for preparing the Al / SiC composite material as described in any example of the third aspect of the present application, comprising the following steps:

[0070] Aluminum and / or aluminum alloy is heated to be molten, filled into the pores of the porous SiC preform, and coated on the outer surface of the porous SiC preform to form the Al phase, thereby preparing the Al / SiC composite material.

[0071] It is understood that the molten Al phase in this application can be derived from any aluminum alloy commonly selected in the art, by adding elements such as magnesium (Mg), copper (Cu), silicon (Si), and manganese (Mn). For example, usable aluminum alloys include, but are not limited to, one or more of ADC12, ZL101, ZL101A, ZL105, and ZL105A.

[0072] In one example, the filling method includes vacuum infiltration and / or pressure infiltration.

[0073] The process parameters of vacuum pressure infiltration include: vacuum degree ≤ -95kPa, pressure 3Bar to 6Bar. In one specific example, the preparation method of the battery stack shell includes the following steps:

[0074] S10, selecting a first particle size SiC powder and a second particle size SiC powder with a particle size ratio of ≥2 according to a ratio of the total volume of the first particle size SiC powder to the total volume of the second particle size SiC powder of (0.5-1):1; mixing the first particle size SiC powder and the second particle size SiC powder to prepare a SiC matrix;

[0075] S20, adding an inorganic binder and an organic binder to the SiC matrix and mixing them to prepare a SiC blank;

[0076] S30, granulating the SiC blank, drying and dehydrating it, and then placing it into a stack housing mold for compression molding; after compression molding, performing high-temperature sintering at a temperature of 600° C. to 750° C., discharging the organic binder, and preparing a porous SiC preform;

[0077] S40. Place the porous SiC preform into a stack shell mold, apply pressure of 3 to 6 Bar under a vacuum degree of less than -95 kPa, infiltrate the molten Al phase into the pores of the porous SiC preform and wrap the outer surface of the porous SiC preform to prepare an Al / SiC composite material.

[0078] In a fifth aspect of the present application, a fuel cell stack shell is provided, comprising the porous SiC preform described in any example of the first aspect of the present application or the Al / SiC composite material described in any example of the third aspect of the present application.

[0079] In one example, the stack housing is a fuel cell stack housing.

[0080] The stack housing material provided in this application has low density and high strength, as well as a low thermal expansion coefficient and high thermal conductivity, which can prevent damage to the stack. Furthermore, Al has a good surface effect, enabling near-net shape formation.

[0081] In a sixth aspect of the present application, a method for preparing the fuel cell stack housing according to the fifth aspect of the present application is provided, comprising the following steps:

[0082] S10, selecting a first particle size SiC powder and a second particle size SiC powder with a particle size ratio of ≥2 according to a ratio of the total volume of the first particle size SiC powder to the total volume of the second particle size SiC powder of (0.5-1):1; mixing the first particle size SiC powder and the second particle size SiC powder to prepare a SiC matrix;

[0083] S20, adding an inorganic binder and an organic binder to the SiC matrix and mixing them to prepare a SiC blank;

[0084] S30, granulating the SiC blank, drying and dehydrating it, and then placing it into a stack housing mold for compression molding; after compression molding, performing high-temperature sintering at a temperature of 600° C. to 750° C., discharging the organic binder, and preparing a porous SiC preform;

[0085] S40, placing the porous SiC preform into a stack housing mold, applying pressure of 3 to 6 Bar under a vacuum degree of less than -95 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0086] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0087] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are all commercially available products.

[0088] Example 1

[0089] Example 1 of the present application provides a method for preparing an Al / SiC composite material and a stack shell, and the specific steps are as follows:

[0090] S10, selecting two silicon carbide particles of 200 μm and 50 μm in a ratio of 1:1 between the total volume of the first SiC particle size and the total volume of the second SiC particle size; mixing the first SiC particle size and the second SiC particle size to prepare a SiC matrix;

[0091] S20, adding a mixed binder to the SiC matrix, wherein the volume ratio of the SiC matrix to the mixed binder is 2.5:7.5, and an aqueous solution of 5% wt methyl cellulose and 5% wt sodium silicate is used in the mixed binder, wherein the volume ratio of the methyl cellulose to the aqueous solution of sodium silicate is 1:1, and the mixture is mixed to prepare a SiC blank;

[0092] S30. Granulate the SiC billet, dry and dehydrate it, and then place it into a fuel cell shell mold for compression molding; after compression molding, perform high-temperature sintering, with the first stage temperature at 120°C and sintering for 20 minutes; the second stage sintering temperature at 750°C and sintering for 1 hour; discharge the organic binder to prepare a porous SiC preform, with the mass ratio of sodium silicate to SiC matrix being 0.087:1; the porous SiC preform has a porosity of 75%.

[0093] S40, placing the porous SiC preform into a stack housing mold, applying a pressure of 5 Bar under a vacuum degree of -90 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0094] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0095] Example 2

[0096] Example 2 of the present application provides a method for preparing an Al / SiC composite material and a stack shell, and the specific steps are as follows:

[0097] S10, selecting two silicon carbide particles of 200 μm and 50 μm in a ratio of 1:1 between the total volume of the first SiC particle size and the total volume of the second SiC particle size; mixing the first SiC particle size and the second SiC particle size to prepare a SiC matrix;

[0098] S20, adding a mixed binder to the SiC matrix, wherein the volume ratio of the SiC matrix to the mixed binder is 3:7, and an aqueous solution of 5% wt methyl cellulose and 5% wt sodium silicate is used in the mixed binder, wherein the volume ratio of the methyl cellulose to the aqueous solution of sodium silicate is 1:1, and mixing to prepare a SiC blank;

[0099] S30. Granulate the SiC billet, dry and dehydrate it, and then place it into a fuel cell shell mold for compression molding; after compression molding, perform high-temperature sintering, with the first stage temperature at 120°C and sintering for 20 minutes; the second stage sintering temperature at 750°C and sintering for 1 hour; discharge the organic binder to prepare a porous SiC preform, with the mass ratio of sodium silicate to SiC matrix being 0.072:1; the porous SiC preform has a porosity of 70%.

[0100] S40, placing the porous SiC preform into a stack housing mold, applying a pressure of 5 Bar under a vacuum degree of -90 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0101] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0102] Example 3

[0103] Example 3 of the present application provides a method for preparing an Al / SiC composite material and a stack shell, and the specific steps are as follows:

[0104] S10, selecting two silicon carbide particles of 200 μm and 50 μm in a ratio of 1:1 between the total volume of the first SiC particle size and the total volume of the second SiC particle size; mixing the first SiC particle size and the second SiC particle size to prepare a SiC matrix;

[0105] S20, adding a mixed binder to the SiC matrix, wherein the volume ratio of the SiC matrix to the mixed binder is 4:6, and an aqueous solution of 5% wt methyl cellulose and 5% wt sodium silicate is used in the mixed binder, wherein the volume ratio of the methyl cellulose to the aqueous solution of sodium silicate is 1:1, and mixing to prepare a SiC blank;

[0106] S30. Granulate the SiC billet, dry and dehydrate it, and then place it into a fuel cell shell mold for compression molding; after compression molding, perform high-temperature sintering, with the first stage temperature at 120°C and sintering for 20 minutes; the second stage sintering temperature at 750°C and sintering for 1 hour; discharge the organic binder to prepare a porous SiC preform, with the mass ratio of sodium silicate to SiC matrix being 0.053:1; the porous SiC preform has a porosity of 60%.

[0107] S40, placing the porous SiC preform into a stack housing mold, applying a pressure of 5 Bar under a vacuum degree of -90 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0108] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0109] Comparative Example 1

[0110] Comparative Example 1 is basically the same as Example 3, except that no inorganic binder is added in Comparative Example 1. The specific steps are as follows:

[0111] S10, selecting two silicon carbide particles of 200 μm and 50 μm in a ratio of 1:1 between the total volume of the first SiC particle size and the total volume of the second SiC particle size; mixing the first SiC particle size and the second SiC particle size to prepare a SiC matrix;

[0112] S20, adding an organic binder to the SiC matrix, wherein the volume ratio of the SiC matrix to the organic binder is 4:6, and 5% wt methyl cellulose is used in the organic binder, and the mixture is mixed to prepare a SiC blank;

[0113] S30. Granulate the SiC billet, dry and dehydrate it, and then place it into a fuel cell shell mold for compression molding; after compression molding, perform high-temperature sintering, with the first stage temperature at 120°C and sintering for 20 minutes; the second stage temperature at 750°C and sintering for 1 hour; discharge the organic binder to prepare a porous SiC preform, wherein the porous SiC preform has a porosity of 60%.

[0114] S40, placing the porous SiC preform into a stack housing mold, applying a pressure of 5 Bar under a vacuum degree of -90 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0115] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0116] Comparative Example 2

[0117] Comparative Example 2 is basically the same as Example 3, except that a 1% wt aqueous solution of sodium silicate is used. In the porous SiC preform finally prepared, the mass ratio of sodium silicate to SiC matrix is 0.01:1.

[0118] The specific steps are as follows:

[0119] S10, selecting two silicon carbide particles of 200 μm and 50 μm in a ratio of 1:1 between the total volume of the first SiC particle size and the total volume of the second SiC particle size; mixing the first SiC particle size and the second SiC particle size to prepare a SiC matrix;

[0120] S20, adding a mixed binder to the SiC matrix, wherein the volume ratio of the SiC matrix to the mixed binder is 4:6, and an aqueous solution of 5% wt methyl cellulose and 1% wt sodium silicate is used in the mixed binder, wherein the volume ratio of the methyl cellulose to the aqueous solution of sodium silicate is 1:1, and mixing to prepare a SiC blank;

[0121] S30. Granulate the SiC billet, dry and dehydrate it, and then place it into a fuel cell shell mold for compression molding; after compression molding, perform high-temperature sintering, with the first stage temperature at 120°C and sintering for 20 minutes; the second stage sintering temperature at 750°C and sintering for 1 hour; discharge the organic binder to prepare a porous SiC preform, with the mass ratio of sodium silicate to SiC matrix being 0.01:1; the porous SiC preform has a porosity of 90%.

[0122] S40, placing the porous SiC preform into a stack housing mold, applying a pressure of 5 Bar under a vacuum degree of -90 kPa, filling the pores of the porous SiC preform with molten Al phase, and wrapping the outer surface of the porous SiC preform with Al phase, to prepare an Al / SiC composite material;

[0123] S50. Aluminum is infiltrated into the joints of the Al / SiC composite material to prepare a complete stack shell.

[0124] The Al / SiC composite materials prepared in the examples and comparative examples were characterized and tested.

[0125] The test method or standard is:

[0126] (1) Density: Tested based on the contents of GB / T 3190-2020;

[0127] (2) Young's modulus: tested based on the content recorded in GB / T 22315-2008;

[0128] (3) Thermal expansion coefficient: GB / T 3074.4;

[0129] (4) Thermal conductivity: Thermal conductivity was tested based on the ASTM E1461 flash method.

[0130] The test results are shown in Table 1:

[0131] Table 1

[0132]

[0133] As shown in Table 1, the density of the Al / SiC composite material provided in Examples 1 to 3 is 2.77 g / cm 3 ~2.99g / cm 3 , lower than the density of SiC (3.2g / cm 3). At the same time, the Young's modulus of the Al / SiC composite materials of Examples 1 to 3 is 117GPa~157GPa, indicating that they have high strength; and the thermal conductivity is 150W / m·K~165W / m·K, which has excellent thermal conductivity. Further, in Example 3, Al is 60vol%, and its Young's modulus values are higher than those of Examples 1 and 2, the thermal expansion coefficient value is lower than that of Examples 1 and 2, and the thermal conductivity value is higher than that of Examples 1 and 2; indicating that when Al is 50vol%~60vol%, the Al / SiC composite material has higher strength, lower thermal expansion coefficient and better thermal conductivity. Similarly, in Example 2, Al is 70vol%, which has higher strength, lower thermal expansion coefficient and better thermal conductivity than Example 1. By comparing Comparative Examples 1 and 2 with Example 3, it is found that the composite materials prepared in Comparative Examples 1 and 2 have a low Young's modulus, a lower strength than Example 3, and a lower thermal conductivity than Example 3.

[0134] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A porous SiC preform, characterized in that: The raw materials for preparing the porous SiC preform are composed of the raw materials for preparing the SiC matrix, an inorganic binder and a pore-forming agent, wherein the pore-forming agent is an organic binder, and the porosity of the porous SiC preform is 45% to 75%; The mass ratio of the inorganic binder to the raw material for preparing the SiC substrate is (0.02-0.1):1; The inorganic binder includes one or more of sodium silicate and lithium silicate; The raw materials for preparing the SiC matrix are composed of SiC powder of a first particle size and SiC powder of a second particle size, wherein the particle size of the SiC powder of the first particle size is 50 μm to 500 μm; and the particle size of the SiC powder of the second particle size is 25 μm to 250 μm. The particle size ratio of the SiC powder of the first particle size to the SiC powder of the second particle size is ≥2; The ratio of the total volume of the SiC powder of the first particle size to the total volume of the SiC powder of the second particle size is (0.5-1):

1.

2. A method for preparing a porous SiC preform according to claim 1, characterized in that: The following steps are involved: The porous SiC preform is prepared by mixing the raw materials for preparing the porous SiC preform, forming and sintering the mixture, and then removing the porogen.

3. The method for preparing a porous SiC preform according to claim 2, wherein: The sintering process parameters include: sintering temperature is 600℃~750℃.

4. An Al / SiC composite material, characterized in that: The Al / SiC composite material comprises the porous SiC preform according to claim 1 and an Al phase filling pores in the porous SiC preform and covering the outer surface of the porous SiC preform.

5. The Al / SiC composite material according to claim 4, characterized in that In the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (25%-55%):(75%-45%).

6. The Al / SiC composite material according to claim 5, characterized in that In the Al / SiC composite material, the volume ratio of the porous SiC preform to the Al phase is (40%-50%):(60%-50%).

7. A method for preparing the Al / SiC composite material according to any one of claims 4 to 6, characterized in that: The following steps are involved: Aluminum and / or aluminum alloy is heated to be molten, filled into the pores of the porous SiC preform, and coated on the outer surface of the porous SiC preform to form the Al phase, thereby preparing the Al / SiC composite material.

8. The method for preparing the Al / SiC composite material according to claim 7, characterized in that: Filling methods include vacuum infiltration and / or pressure infiltration, Among them, the process parameters of vacuum pressure infiltration include: vacuum degree ≤-95 kPa, pressure 3 Bar ~6 Bar.

9. A battery stack casing, characterized in that: The method comprises the porous SiC preform according to claim 1 or the Al / SiC composite material according to any one of claims 4 to 6.

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