Aluminum-based silicon carbide composite material, and preparation method and application thereof

Abstract

The application belongs to the technical field of aluminum-based silicon carbide materials, and discloses an aluminum-based silicon carbide composite material and a preparation method and application thereof, which comprises the following steps: (1) adding the composite powder obtained by mixing silicon carbide and a binder into a printing device to print to obtain a silicon carbide blank; (2) performing a degreasing treatment on the silicon carbide blank to obtain a silicon carbide preform; (3) performing pre-oxidation on the silicon carbide preform; (4) performing vacuum impregnation on the silicon carbide preform with cross-linkable solution PCS, and then performing solidification; (5) performing pyrolysis on the silicon carbide preform; and (6) performing vacuum pressure impregnation of aluminum alloy on the silicon carbide preform to obtain the aluminum-based silicon carbide composite material. By introducing the cross-linkable liquid PCS, the difficulty that the strength of the silicon carbide preform sharply decreases after pre-oxidation and the preform cannot be shaped can be effectively solved, and even the preform can be prevented from being powdered.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum-based silicon carbide materials, and more particularly relates to an aluminum-based silicon carbide composite material and a preparation method and application thereof. BACKGROUND

[0002] High volume fraction SiC / Al composite materials have become important materials in the fields of aerospace, electronic packaging, thermal management, etc. due to their high thermal conductivity, excellent mechanical properties, low thermal expansion coefficient, etc. With the development of high-performance components with more complex structures in key equipment, higher requirements are put forward for the preparation and processing technology of SiC / Al composite materials. Generally, the methods for preparing SiC / Al composite materials mainly include powder metallurgy, casting and infiltration. However, when manufacturing SiC / Al composite material components with complex structures, these traditional methods face challenges such as low density, internal defects, difficulty in accurately controlling local composition and structure, etc. Moreover, SiC / Al composite materials formed by traditional methods also have great difficulties in subsequent processing, as described in the processing method of the aluminum-based silicon carbide structural part for a gyroscope disclosed in ZL201110256283.2, the current processing method of aluminum-based silicon carbide structural parts has high requirements for tools, high processing difficulty and high cost. Therefore, it is difficult to meet the demand for rapidly manufacturing individualized, fine, lightweight and complex SiC / Al composite material components, which greatly limits the development and application of SiC / Al composite materials.

[0003] The preparation process of aluminum-based silicon carbide composite materials with medium and low volume fractions has become mature, and the performance and stability of the products are relatively ideal. For high volume fraction aluminum-based silicon carbide composite materials, most of them are currently prepared by a composite method combining silicon carbide and aluminum infiltration. The preparation of the preform mostly goes through a sintering stage, and high sintering temperature (greater than 1000℃) causes high energy consumption, and the sintering process also causes a certain degree of shrinkage, which greatly affects the dimensional accuracy of the structural part. At the same time, defects such as bubbling, porosity and cracking will occur during the sintering process, and most importantly, impurity phases and brittle Al4C3 phases are easily produced.

[0004] Although the method of additive manufacturing can form complex structural parts while maintaining good dimensional accuracy. However, the loose bulk density (~1.2g / cm 3 ) and tap density (~1.6g / cm 3) are not high, which shows that a higher volume fraction of silicon carbide cannot be obtained by the method of additive manufacturing. In addition, a large amount of free carbon remains in the silicon carbide preform after debinding, and the carbon source will directly react with liquid aluminum alloy to generate brittle phase Al4C3. The existence of brittle phase Al4C3 and unreacted free carbon will seriously affect the microstructure and mechanical properties of SiC / Al composite material. Therefore, when obtaining a silicon carbide preform by additive manufacturing, it is necessary to improve the volume fraction of silicon carbide in the SiC / Al composite material by appropriate post-processing while taking into account the problem of strength reduction of the preform after oxidation of the residual carbon. The patent "CN104177621B A new liquid polycarbosilane and its preparation method and application" discloses a new cross-linkable liquid polycarbosilane with low viscosity and high storage stability. Using the cross-linkable liquid PCS disclosed in the patent to do PIP processing can solve the above two problems at the same time. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides an aluminum-based silicon carbide composite material and a preparation method and application thereof. The method introduces cross-linkable liquid polycarbosilane to solve the problem of preform pulverization after oxidation of residual carbon.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of an aluminum-based silicon carbide composite material is provided, which comprises the following steps:

[0007] (1) adding the composite powder obtained by mixing silicon carbide and a binder into a printing device to print to obtain a silicon carbide green body;

[0008] (2) performing debinding treatment on the silicon carbide green body to obtain a silicon carbide preform;

[0009] (3) performing pre-oxidation on the silicon carbide preform;

[0010] (4) vacuum impregnating the silicon carbide preform with cross-linkable solution PCS, and then solidifying;

[0011] (5) performing pyrolysis on the silicon carbide preform;

[0012] (6) performing vacuum pressure impregnation of aluminum alloy on the silicon carbide preform to obtain an aluminum-based silicon carbide composite material.

[0013] Further, the particle size of the silicon carbide in the composite powder is 10-100 μm, the particle size of the binder is 5-30 μm, the mass fraction of the silicon carbide is 80-90%, and the mass fraction of the binder is 10-20%.

[0014] Further, the type of the binder is epoxy resin or phenolic resin.

[0015] Further, the debinding holding temperature is 600-800 DEG C, and the holding time is 1.5-3h.

[0016] Further, in the pre-oxidation process, the pre-oxidation temperature is 950-1200 DEG C, and the holding time is 1-4h.

[0017] Further, the cross-linkable liquid PCS is a six-membered ring structure, and its structural formula is as follows:

[0018]

[0019] wherein R independently contains C=C, C≡C or cyclopropyl; m is a positive integer, and m>=3; 0.05<=n<=2.

[0020] Further, the catalyst used for curing and cross-linking is DCP or platinum, the content of DCP is 0.1-0.5wt%, and the concentration of the platinum catalyst is 20ppm.

[0021] Further, the pyrolysis temperature is 1000-1400 DEG C, the heating rate is 3-5 DEG C / min; the pressure of vacuum infiltration is 1-9MPa, the infiltration temperature is 750-900 DEG C, and the holding time is 2-4h.

[0022] The application further provides an aluminum-based silicon carbide composite material prepared by the preparation method of the aluminum-based silicon carbide composite material.

[0023] The application further provides application of the aluminum-based silicon carbide composite material in aerospace, electronic packaging and thermal management equipment.

[0024] Overall, compared with the prior art, the aluminum-based silicon carbide composite material and the preparation method and application thereof provided by the application mainly have the following beneficial effects:

[0025] 1. The application can effectively solve the difficulty that the strength of the silicon carbide preform sharply decreases after pre-oxidation and the preform cannot be shaped, and even the preform is powdered. After the pre-oxidized preform is infiltrated with the cross-linkable liquid PCS, the strength of the preform can be ensured after curing, thereby providing guarantee for subsequent processes. In addition, the residual carbon after debinding seriously affects the microstructure of the SiC / Al composite material, and the surface of the SiC / Al composite material has serious pore defects and even layered peeling. The application gradually removes the residual carbon through the above method.

[0026] 2. Although complex structural parts can be shaped by the method of additive manufacturing, due to the limitations of the process, the bulk density of the composite powder will not be too high, which will directly affect the volume fraction of silicon carbide in the final aluminum-based silicon carbide composite material, so as to obtain a higher volume fraction, the cross-linkable liquid PCS is used as the raw material of the PIP process, which can not only adjust the volume fraction of silicon carbide, but also achieve the gain effect.

[0027] 3. By using vacuum pressure infiltration of aluminum alloy, not only can the gas in the porous silicon carbide preform be removed, but also the aluminum liquid can be infiltrated into the voids generated during the sintering process of the binder and repeated PIP by pressure, thereby forming a structurally dense aluminum-based silicon carbide composite material.

[0028] 4. By using liquid PCS to carry out the PIP process, on the one hand, it can regulate the porosity of the silicon carbide preform itself, that is, the volume fraction of silicon carbide; on the other hand, due to the cross-linkable side chain in the liquid PCS, this feature can be used to solve the problem of weakening of the strength of the oxidized silicon carbide preform, that is, by using liquid PCS to realize the regulation of the volume fraction of silicon carbide and using the cross-linking property to strengthen the strength of the silicon carbide preform. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flowchart of a preparation method of an aluminum-based silicon carbide composite material provided by the present application.

[0030] Figure 2 is a bending performance curve of SiC / Al composite materials with different PIP times obtained by the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0032] Please refer to Figure 1 , the present application provides a preparation method of an aluminum-based silicon carbide composite material mainly comprising the following steps:

[0033] Step 1: The composite powder obtained by mixing silicon carbide and a binder is added to a printing device to obtain a silicon carbide blank.

[0034] The particle size of the silicon carbide in the composite powder is 10-100 microns, the particle size of the binder is 5-30 microns, the mass fraction of the silicon carbide is 80-90%, and the type of the binder is epoxy resin or phenolic resin. The mass fraction of the binder is 10-20%.

[0035] The printing method can be selective laser sintering (SLS), digital light processing (DLP), stereolithography (SLA), and three-dimensional inkjet printing (3DP).

[0036] Step two: the silicon carbide green body is subjected to debinding treatment to obtain a silicon carbide preform.

[0037] The debinding holding temperature is 600-800 DEG C, and the holding time is 1.5-3 hours.

[0038] Step three: the silicon carbide preform is subjected to pre-oxidation.

[0039] During the pre-oxidation process, the pre-oxidation temperature is 950-1200 DEG C, and the holding time is 1-4 hours.

[0040] Step four: the silicon carbide preform is subjected to vacuum impregnation with cross-linkable solution PCS, and then solidified.

[0041] The cross-linkable liquid PCS is a six-membered ring structure, and its structural formula is:

[0042]

[0043] wherein R independently of one another contains a reactive group of C=C, C≡C or cyclopropyl, etc., m is a positive integer, and m≥3; 0.05≤n≤2; wherein R independently of one another is R 1 —(CR 2 2) x —, wherein R 1 is CR 3 2=CR 3 —, R 3 and R 2 independently of one another are H or C1-C4 alkyl (such as methyl, ethyl, propyl, butyl, including isomers thereof), and x is 0, 1, 2 or 3.

[0044] The catalyst used for curing and cross-linking is DCP (dicumyl peroxide) or platinum, the content of DCP is 0.1wt% to 0.5wt%, and the concentration of platinum catalyst is 20ppm. After adding DCP, stirring and dissolving (about 0.5h-1h), impregnating the composite material, removing bubbles by vacuumizing, and under the protection of airtight or nitrogen or argon, heating to 100℃-120℃ at a heating rate of 3℃ / min, and keeping for 1h, then heating to 130℃-160℃ at a heating rate of 0.5℃ / min, and keeping for 2h; or curing at 125℃-140℃ for 2h-3h. The initial curing temperature under pure nitrogen is about 5℃-10℃ lower than that in airtight air, and there is also a fluctuation of 5℃-10℃ between different batches.

[0045] Step five, pyrolyzing the silicon carbide preform.

[0046] The pyrolysis temperature is 1000℃-1400℃, and the heating rate is 3℃ / min-5℃ / min.

[0047] Step six, vacuum pressure impregnating aluminum alloy into the silicon carbide preform to obtain an aluminum-based silicon carbide composite material.

[0048] The pressure of vacuum impregnation is 1MPa-9MPa, the impregnation temperature is 750℃-900℃, and the holding time is 2h-4h.

[0049] The application also provides an aluminum-based silicon carbide composite material prepared by the preparation method of the aluminum-based silicon carbide composite material as described above.

[0050] The application also provides an application of the aluminum-based silicon carbide composite material as described above in aerospace, electronic packaging, and thermal management equipment.

[0051] The application will be further described in detail in the following several embodiments.

[0052] Embodiment 1

[0053] In this embodiment, the SiC / Al composite material is prepared by using silicon carbide powder and 6063Al as main raw materials, and cross-linkable liquid PCS as a raw material for controlling porosity in post-processing.

[0054] In this embodiment, the SiC / Al composite material with different porosities is prepared by the following method:

[0055] S1 Silicon carbide powder with different particle sizes 10 μm, 30 μm, 40 μm, 70 μm, 90 μm and epoxy resin (15 μm) binder mixed after the composite powder (sample 1, 2, 3, 4, 5 respectively) is added to the selective laser sintering printing equipment for printing, wherein the printing parameters are laser power 9W, filling speed 2000mm / s, filling thickness 0.1mm, and silicon carbide green body is obtained.

[0056] S2 The silicon carbide green body obtained by printing with different particle sizes is subjected to debinding treatment, wherein the holding temperature during debinding is 800℃, and the holding time is 2h, and then a silicon carbide preform is obtained.

[0057] S3 The silicon carbide preform is subjected to pre-oxidation treatment, and the silicon carbide preform after debinding in step S2 contains a large amount of residual carbon, the pre-oxidation temperature is 950℃, and the holding time is 1.5h, and then the final silicon carbide porous skeleton is obtained.

[0058] S4 Cross-linkable liquid PCS containing vinyl groups in the side chain is used, the molecular weight of the liquid PCS is 1050-1600, M w / M n = 4-9 The catalyst used for curing and cross-linking is DCP (dicumyl peroxide), and the content of DCP is 0.2wt%. After adding DCP, stirring and dissolving (about 1h), impregnating the composite material, removing bubbles under vacuum, and in a closed environment, curing at 120℃ for 3h.

[0059] S5 The silicon carbide preform is subjected to pyrolysis, the pyrolysis temperature is 1200℃, the heating rate is 5℃ / min, and the holding time is 2h.

[0060] S6 The silicon carbide porous skeleton obtained by printing with different particle sizes is subjected to vacuum pressure impregnation of aluminum, wherein the pressure of vacuum impregnation is 8MPa, the impregnation temperature is 800℃, and the holding time is 2h, and the final SiC / Al composite material is obtained.

[0061] The properties of the silicon carbide porous skeleton obtained by printing with different particle sizes are characterized, and the specific data are shown in Table 1 and Table 2. The properties of the final SiC / Al composite material of sample 1, 2, 3, 4, 5 are characterized, and different samples of SiC / Al composite material are named as A1, A2, A3, A4, A5. The results show that the particle size has an important influence on the porosity of the silicon carbide preform, and further, the volume fraction of silicon carbide is affected.

[0062] Table 1 Physical property data of different samples

[0063]

[0064] Table 2 Performance data of different SiC / Al composite material samples

[0065]

[0066] Example 2

[0067] In this embodiment, the SiC / Al composite material is prepared by using silicon carbide powder and 6063 Al as the main printing raw materials and cross-linkable liquid PCS as the raw material for regulating porosity in post-processing.

[0068] In this embodiment, the SiC / Al composite material with different porosities is prepared by the following method:

[0069] S1: The composite powder obtained by mixing the silicon carbide powder with different particle sizes (70 μm) and the epoxy resin (15 μm) binder is added into the selective laser sintering printing equipment for printing, wherein the printing parameters are as follows: the laser power is 10 W, the filling speed is 2500 mm / s, and the filling thickness is 0.15 mm, and the silicon carbide green body is obtained.

[0070] S2: The silicon carbide green body obtained by printing is subjected to debinding treatment, wherein the holding temperature in the debinding process is 800 ℃, and the holding time is 2 h, and then the silicon carbide preform is obtained.

[0071] S3: The silicon carbide preform is subjected to pre-oxidation treatment, and the silicon carbide preform after debinding in step S2 contains a large amount of residual carbon. The pre-oxidation temperature is 950 ℃, and the holding time is 1.5 h, and then the final silicon carbide porous skeleton is obtained.

[0072] S4: The cross-linkable liquid PCS with a side chain containing a vinyl group is used, and the molecular weight of the liquid PCS is 1050-1600, M w / M n = 4-9. The catalyst used for curing and cross-linking is DCP (dicumyl peroxide), and the content of DCP is 0.3 wt%. After adding DCP and stirring for dissolution (about 1 h), the composite material is impregnated, vacuumized to remove bubbles, and cured at 140 ℃ for 3 h in a closed environment.

[0073] S5: The silicon carbide preform is subjected to pyrolysis, and the pyrolysis temperature is 1200 ℃, the heating rate is 5 ℃ / min, and the holding time is 2 h. As Figure 1 cycled to S4, and then the porosity of the sample is tested by the Archimedes method every time the PIP is performed, and the results are shown in Table 3. Please refer to Figure 2 The presence of residual carbon will seriously affect the SiC / Al composite material, and the bending strength of PIP-0 is only 200 MPa; and for the samples subjected to different PIP times, the performance is improved by nearly one time after removing the residual carbon, reaching 380 MPa. The results show that the method provided by the present application can not only effectively regulate the volume fraction of silicon carbide, but also significantly improve the mechanical properties of the material.

[0074] Table 3 Performance data of SiC / Al composite samples with different PIP times of sample A4

[0075]

[0076] S6 The SiC / Al composite material was prepared by vacuum pressure infiltration of the porous skeleton of silicon carbide with different particle sizes, wherein the pressure of vacuum infiltration was 8 MPa, the infiltration temperature was 800 DEG C, and the holding time was 2 h.

[0077] It can be known from the performance data of SiC / Al composite samples with different PIP times that the volume fraction of silicon carbide in the SiC / Al composite material prepared by additive manufacturing can be effectively controlled by this method, that is, the volume fraction of silicon carbide in the SiC / Al composite material is controlled by the PIP process.

[0078] Those skilled in the art will easily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an aluminum-based silicon carbide composite material, characterized in that, The method includes the following steps: (1) The composite powder after mixing silicon carbide and binder is added to the printing equipment for printing to obtain silicon carbide blank; (2) The silicon carbide preform is degreased to obtain a silicon carbide preform; (3) The silicon carbide preform is pre-oxidized; (4) Vacuum impregnate the silicon carbide preform with a crosslinkable solution PCS, and then cure it; (5) Pyrolysis of silicon carbide preform; (6) Vacuum pressure impregnation of aluminum alloy into the silicon carbide preform to obtain aluminum-based silicon carbide composite material.

2. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: The composite powder has a silicon carbide particle size of 10 μm to 100 μm, a binder particle size of 5 μm to 30 μm, a silicon carbide mass fraction of 80% to 90%, and a binder mass fraction of 10% to 20%.

3. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: The adhesive is either epoxy resin or phenolic resin.

4. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: The degreasing and heat preservation temperature is 600℃~800℃, and the heat preservation time is 1.5h~3h.

5. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: During the pre-oxidation process, the pre-oxidation temperature is 950℃~1200℃, and the holding time is 1h~4h.

6. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: Crosslinkable liquid PCS has a six-membered ring structure, and its structural formula is as follows: Where R independently contains C=C, C≡C or cyclopropyl; m is a positive integer and m≥3; 0.05≤n≤2.

7. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: The catalyst used for curing and crosslinking is DCP or platinum, with DCP content of 0.1wt% to 0.5wt% and platinum catalyst concentration of 20ppm.

8. The method for preparing the aluminum-based silicon carbide composite material according to any one of claims 1-7, characterized in that: The pyrolysis temperature is 1000℃~1400℃, the heating rate is 3℃ / min~5℃ / min; the vacuum impregnation pressure is 1MPa~9MPa, the impregnation temperature is 750℃~900℃, and the holding time is 2h~4h.

9. An aluminum-based silicon carbide composite material, characterized in that: The aluminum-based silicon carbide composite material is prepared by the preparation method of the aluminum-based silicon carbide composite material according to any one of claims 1-8.

10. The application of the aluminum-based silicon carbide composite material of claim 9 in aerospace, electronic packaging, and thermal management equipment.

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