Layered gradient Al-Al based composite material, and preparation method and application thereof

Abstract

The present application relates to the field of powder metallurgy composite material, in particular to a layered gradient Al-Al based composite material and a preparation method and application thereof, the material comprises a matrix layer and a reinforcing layer, the matrix layer is pure aluminum or aluminum alloy, the components and mass percentage of the aluminum alloy are as follows: Si 7.5%-10.5%, Cu 2.0%-3.5%, and the balance is Al; the reinforcing layer is a ceramic reinforced aluminum based composite material, the components and mass percentage of the ceramic reinforced aluminum based composite material are as follows: Si 7.5%-10.5%, Cu 2.0%-3.5%, ceramic powder 6%-18%, and the balance is Al. The layered gradient Al-Al based composite material disclosed in the present application comprises a matrix layer and a reinforcing layer, the interface connection strength between the matrix layer and the reinforcing layer is greater than 500 MPa, the tensile strength of the material is greater than 520 MPa, and the yield strength is greater than 405 MPa. The layered gradient Al-Al based composite material disclosed in the present application has high heat resistance, high wear resistance and excellent structural characteristics, and is an excellent alternative material for automobile brake discs.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy composite materials, specifically to a layered gradient Al-Al based composite material, its preparation method, and its application. Background Technology

[0002] Lightweighting is a global trend in the automotive industry, and weight reduction is crucial for vehicles. In vehicle braking systems, the brake disc and friction pads work together to convert the force applied by the driver's pedal into braking force, causing the vehicle to slow down or stop. The brake disc is a critical component of the braking system, requiring normal operation in harsh environments such as 0-100% humidity and -40-600℃ temperatures. This places high demands on the heat resistance and corrosion resistance of the materials used. Currently, cast iron is a common material for brake discs; however, cast iron has a high density, which is detrimental to reducing the overall weight of the vehicle body, and its corrosion resistance is also poor.

[0003] Aluminum is a lightweight, corrosion-resistant metal with good thermal conductivity. By adding other alloying elements, aluminum alloys possess high mechanical strength and excellent corrosion resistance. Aluminum and aluminum alloys are among the most widely used metallic materials. However, their poor heat resistance and wear resistance significantly limit their application in critical components such as vehicle brake discs. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a layered gradient Al-Al based composite material prepared by powder metallurgy, combining aluminum and aluminum alloys with aluminum-based composite materials to form a composite material with good wear resistance, heat resistance, and ductility. Specifically, this invention includes the following:

[0005] A layered gradient Al-Al based composite material includes a matrix layer and a reinforcing layer. The matrix layer is pure aluminum or an aluminum alloy, and the composition and mass percentage of the aluminum alloy are: Si 7.5%-10.5%, Cu 2.0%-3.5%, with the balance being Al. The reinforcing layer is a ceramic-reinforced aluminum matrix composite material, and its composition and mass percentage are: Si 7.5%-10.5%, Cu 2.0%-3.5%, ceramic powder 6%-18%, with the balance being Al.

[0006] Preferably, the volume ratio of the matrix layer to the reinforcing layer is (5-8):1.

[0007] Preferably, the ceramic powder is one or more of B4C, SiC, and Al2O3, and the average particle size of the ceramic powder is 15-30 μm.

[0008] Preferably, the interfacial bonding strength between the matrix layer and the reinforcing layer is >500MPa, and the tensile strength and yield strength of the material are >520MPa and >405MPa.

[0009] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0010] (1) The ingredients are prepared and mixed according to the ratio of Si 7.5%-10.5%, Cu 2.0%-3.5%, ceramic powder 6%-18%, and the balance is Al, so as to obtain ceramic reinforced aluminum matrix composite powder with an average particle size of 15-30μm.

[0011] (2) Pure aluminum powder or aluminum alloy powder with a composition and mass percentage of Si 7.5%-10.5%, Cu 2.0%-3.5% and the balance Al is used as the matrix layer powder, and the average particle size of the matrix layer powder is 15-30μm.

[0012] (3) The ceramic-reinforced aluminum matrix composite powder and the matrix layer powder are molded according to the volume ratio to obtain a composite material blank;

[0013] (4) The composite material blank is subjected to pressureless sintering treatment;

[0014] (5) The composite material blank after pressureless sintering is subjected to thermal densification treatment to obtain the layered gradient Al-Al based composite material.

[0015] Preferably, the batching and mixing method in step (1) is as follows: aluminum matrix powder, alloy element powder and ceramic powder are batched in proportion, and then the batched raw material powder is added to a high-energy ball mill for two-stage ball milling and mixing. The ball-to-material ratio of the first stage ball milling and mixing is 1:(0.8-1.2), the ball mill speed is 250-300 r / min, and the ball milling time is 0.5-1 h; the ball-to-material ratio of the second stage ball milling and mixing is (8-12):1, the ball mill speed is 100-150 r / min, and the ball milling time is 1-1.5 h. After ball milling and mixing, ceramic-reinforced aluminum matrix composite powder is obtained.

[0016] Preferably, step (2) further includes adding the matrix layer powder to a high-energy ball mill for ball milling and mixing, controlling the ball-to-material ratio to be 1:(0.8-1.2), the rotation speed of the ball mill to be 200-250 r / min, and the ball milling time to be 1.5-2 h.

[0017] Preferably, the molding method in step (3) is as follows: First, the ceramic-reinforced aluminum matrix composite powder obtained in step (1) is laid on the lower template of the molding die, and the upper template is used to press and form it with a pressure of 0.8-1.0 MPa; then, the upper template is removed, and the matrix layer powder obtained in step (2) is laid on the pressed ceramic-reinforced aluminum matrix composite powder. After laying, the upper mold is used to press and form it with a pressure of 45-50 MPa to obtain the composite material blank.

[0018] Preferably, the temperature of the pressureless sintering treatment in step (4) is 600-650℃, and the sintering time is ≥2 hours.

[0019] Preferably, the thermal densification process in step (5) is as follows: the composite material blank after pressureless sintering is placed in a mold, heated to 450-500℃, and then a pressure of 15-25MPa is applied. The temperature and pressure are maintained for 0.2-0.5h, and the layered gradient Al-Al based composite material is obtained after cooling.

[0020] Application of the aforementioned layered gradient Al-Al based composite material in automobiles.

[0021] The beneficial effects of this invention are:

[0022] (1) The layered gradient Al-Al based composite material disclosed in this invention includes a matrix layer and a reinforcing layer. The interfacial bonding strength between the matrix layer and the reinforcing layer is >500MPa, and the tensile strength and yield strength of the material are >520MPa and >405MPa, respectively. The layered gradient Al-Al based composite material of this invention not only has the advantages of low density and light weight of aluminum alloy, but also has excellent mechanical properties, high heat resistance, high wear resistance and excellent structural characteristics, making it an excellent alternative material for automotive brake discs.

[0023] (2) The method for preparing the layered gradient Al-Al based composite material disclosed in this invention employs a two-stage ball milling process to ensure uniform mixing of multi-component powders in the ceramic-reinforced aluminum matrix composite material. Simultaneously, the small-sized original powders are uniformly mixed and then milled into large-sized particles, with the average particle size of the treated raw material powders limited to 15-30 μm. This ensures more thorough alloying in subsequent processing, solving problems such as insufficient alloying caused by pressureless sintering. Furthermore, the thermal densification process guarantees the interfacial bonding strength and density of the layered gradient Al-Al based composite material parts prepared by this invention. The method disclosed in this invention has a simple process, controllable cost, and can be industrialized. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. The embodiments shown below do not limit the scope of the invention as described in the claims. Furthermore, the complete contents of the configurations shown in the embodiments below are not limited to those necessary for the solution of the invention described in the claims.

[0025] A layered gradient Al-Al matrix composite material includes a matrix layer and a reinforcing layer. The matrix layer is pure aluminum or an aluminum alloy, and the composition and mass percentage of the aluminum alloy are: Si 7.5%-10.5% (e.g., 8%, 8.5%, 9%, 9.5%, 10%, 10.2%, etc.), Cu 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), with the balance being Al. The reinforcing layer is a ceramic-reinforced aluminum matrix composite material, and its composition and mass percentage are: Si 7.5%-10.5% (e.g., 8%, 8.5%, 9%, 9.5%, 10%, 10.2%, etc.), Cu 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), Cu 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), with the balance being Al. The matrix layer comprises 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), and the reinforcing layer comprises 6%-18% ceramic powder (e.g., 7%, 8%, 10%, 12%, 14%, 16%, etc.), with the balance being Al. The volume ratio of the matrix layer to the reinforcing layer is (5-8):1 (e.g., 5:1, 6:1, 6.5:1, 7:1, 7.5:1, 7.8:1, etc.). The ceramic powder is one or more of B4C, SiC, and Al2O3, and the average particle size of the ceramic powder is 15-30 μm (e.g., 16 μm, 18 μm, 20 μm, 22 μm, 25 μm, 26 μm, 28 μm, etc.). The interfacial bonding strength between the matrix layer and the reinforcing layer is >500 MPa, and the tensile strength and yield strength of the material are >520 MPa and >405 MPa, respectively.

[0026] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0027] (1) Prepare aluminum matrix powder, alloy element powder, and ceramic powder according to the following proportions: Si 7.5%-10.5% (e.g., 8%, 8.5%, 9%, 9.5%, 10%, 10.2%, etc.), Cu 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), ceramic powder 6%-18% (e.g., 7%, 8%, 10%, 12%, 14%, 16%, etc.), with the balance being Al. Then, add the prepared raw material powder to a high-energy ball mill for two-stage ball milling. The ball-to-material ratio in the first stage of ball milling is 1:(0.8-1.2) (e.g., 1:0.9, 1:1, 1:1.1, etc.), and the ball mill speed is 250-300 r / min (e.g., 260 r / min, 270 r / min, 280 r / min, 290 r / min). The ball milling speed is 0 r / min, 295 r / min, etc., and the ball milling time is 0.5-1 h (e.g., 0.6 h, 0.7 h, 0.8 h, 0.9 h, 0.95 h, etc.). The ball-to-material ratio of the second-stage ball milling is (8-12):1 (e.g., 9:1, 10:1, 11:1, etc.), the ball mill speed is 100-150 r / min (e.g., 110 r / min, 120 r / min, 130 r / min, 140 r / min, 145 r / min, etc.), and the ball milling time is 1-1.5 h (e.g., 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.45 h, etc.), resulting in ceramic-reinforced aluminum matrix composite powder with an average particle size of 15-30 μm (e.g., 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, etc.).

[0028] (2) Pure aluminum powder or aluminum alloy powder with the following composition and mass percentage: Si 7.5%-10.5% (e.g., 8%, 8.5%, 9%, 9.5%, 10%, 10.2%, etc.), Cu 2.0%-3.5% (e.g., 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, etc.), with the balance being Al, is used as the matrix layer powder. The matrix layer powder is added to a high-energy ball mill for ball milling and mixing, controlling the ball-to-material ratio at 1:(0.8-1.2) (e.g., 1:0.9, 1:1, 1:1.1, etc.), and the ball mill speed at 200-250 r / min (e.g., 0.8-1.2). Ball milling speeds of 212 r / min, 220 r / min, 230 r / min, 240 r / min, 245 r / min, etc., and milling times of 1.5-2 h (e.g., 1.6 h, 1.7 h, 1.8 h, 1.9 h, etc.) are used to obtain matrix layer powders with average particle sizes of 15-30 μm (e.g., 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, etc.).

[0029] (3) First, the ceramic-reinforced aluminum matrix composite powder obtained in step (1) is laid on the lower template of the molding die, and the upper template is used to press it into shape with a pressure of 0.8-1.0MPa (e.g. 0.85MPa, 0.9MPa, 0.95MPa, 0.98MPa, etc.); then, the upper template is removed, and the matrix layer powder obtained in step (2) is laid on the pressed ceramic-reinforced aluminum matrix composite powder. After laying, the upper mold is used to press it into shape with a pressure of 45-50MPa (e.g. 46MPa, 46.5MPa, 47MPa, 48MPa, 49MPa, etc.) to obtain the composite material blank;

[0030] (4) The composite material blank is subjected to pressureless sintering treatment at a temperature of 600-650℃ (e.g., 610℃, 620℃, 630℃, 640℃, 645℃, etc.) and a sintering time of ≥2 hours (e.g., 2.2h, 2.5h, 2.8h, 3h, 4h, 5h, etc.).

[0031] (5) The composite material blank after pressureless sintering is placed in a mold and heated to 450-500℃ (e.g., 460℃, 470℃, 480℃, 490℃, 495℃, etc.). Then, a pressure of 15-25MPa (e.g., 16MPa, 18MPa, 20MPa, 22MPa, 24MPa, etc.) is applied and the temperature and pressure are maintained for 0.2-0.5h (e.g., 0.3h, 0.35h, 0.4h, 0.45h, etc.). After cooling, the layered gradient Al-Al based composite material is obtained.

[0032] Example 1

[0033] A layered gradient Al-Al based composite material includes: a first layer of powder being a ceramic-reinforced aluminum-based composite material, and a second layer of powder being aluminum or an aluminum alloy, wherein the volume ratio of the first layer to the second layer is 1:6. It should be noted that in this embodiment of the invention, the first layer is the reinforcing layer described above, and the second layer is the matrix layer described above.

[0034] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0035] Step 1: Composition Design of Layered Gradient Al-Al Matrix Composite: The first layer of the powdered ceramic reinforced aluminum matrix composite consists of aluminum matrix powder A, alloying element powder B, and ceramic powder C. Aluminum matrix powder A is pure aluminum powder; alloying element powder B includes Si and Cu; ceramic powder C is selected from one or more of B4C, SiC, and Al2O3. The average particle size of aluminum matrix powder A, alloying element powder B, and ceramic powder C is 20 μm. The composition and mass percentage of the first layer of the ceramic reinforced aluminum matrix composite are: Si: 7.5%, Cu: 3.0%, B4C: 12%, with the balance being Al. The composition and mass percentage of the second layer of the aluminum alloy are: Si: 7.5%, Cu: 3.0%, with the balance being Al.

[0036] Step 2: First layer powder preparation: Aluminum matrix powder, alloy element powder and ceramic powder are added to a high-energy ball mill in proportion and a two-stage ball milling process is carried out. In the first stage of ball milling, the ball-to-material ratio is 1:1, the ball mill speed is 250 r / min, and the ball milling time is 0.8 h. In the second stage of ball milling, after the first stage of ball milling is completed, grinding balls are added to the ball mill to make the ball-to-material ratio 10:1, the ball mill speed is 130 r / min, and the ball milling time is 1.2 h.

[0037] Step 3: Preparation of the second layer of powder: Add the second layer of powder into a high-energy ball mill and carry out the ball milling and mixing process. The ball-to-powder ratio is 1:1, the speed of the ball mill is 220 r / min, and the ball milling time is 2 h.

[0038] Step 4: Compression molding: The first layer of ceramic-reinforced aluminum matrix composite powder is evenly laid on the lower mold plate, and the upper mold plate with the same shape as the lower mold plate is used to press and mold it with a pressure of 0.8MPa; the upper mold plate is removed, the second layer of aluminum or aluminum alloy powder is laid, and the upper mold plate is used to press and mold it with a pressure of 46MPa to obtain a layered gradient Al-Al matrix composite material blank.

[0039] Step 5: Pressureless sintering: Place the pressed blank into a sintering furnace, heat it to 650℃, hold it at that temperature for 2.5 hours, and then cool it to room temperature with the furnace.

[0040] Step 6: Thermal densification treatment: Place the blank after pressureless sintering in a mold, heat it to 450℃ and apply a pressure of 20MPa, keep it at the temperature and pressure for 0.3h, and air cool it to room temperature to obtain a layered gradient Al-Al matrix composite part.

[0041] Example 2

[0042] A layered gradient Al-Al based composite material includes: a first layer of powder being a ceramic-reinforced aluminum-based composite material, and a second layer of powder being aluminum or an aluminum alloy, wherein the volume ratio of the first layer to the second layer is 1:5.

[0043] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0044] Step 1: Design of Layered Gradient Al-Al Matrix Composite Composition: The first layer of the powdered ceramic reinforced aluminum matrix composite composition includes aluminum matrix powder A, alloy element powder B, and ceramic powder C. Aluminum matrix powder A is pure aluminum powder; alloy element powder B includes Si and Cu; ceramic powder C is selected from one or more of B4C, SiC, and Al2O3. The average particle size of aluminum matrix powder A, alloy element powder B, and ceramic powder C is 15 μm. The composition and mass percentage of the first layer of ceramic reinforced aluminum matrix composite are: Si: 8.0%, Cu: 3.5%, SiC: 6%, with the balance being Al. The composition and mass percentage of the second layer aluminum alloy are: Si: 8.0%, Cu: 3.5%, with the balance being Al.

[0045] Step 2: Preparation of the first layer of powder: Add aluminum matrix powder, alloy element powder and ceramic powder to a high-energy ball mill in proportion and carry out a two-stage ball milling process. In the first stage of ball milling, the ball-to-material ratio is 1:1, the speed of the ball mill is 250 r / min, and the ball milling time is 1 h. In the second stage of ball milling, after the first stage of ball milling is completed, add grinding balls to the ball mill to make the ball-to-material ratio 10:1, the speed of the ball mill is 150 r / min, and the ball milling time is 1 h.

[0046] Step 3: Preparation of the second layer of powder: Add the second layer of powder into a high-energy ball mill and carry out the ball milling and mixing process. The ball-to-powder ratio is 1:1, the speed of the ball mill is 230 r / min, and the ball milling time is 1.8 h.

[0047] Step 4: Compression molding: The first layer of ceramic-reinforced aluminum matrix composite powder is evenly laid on the lower mold plate, and the upper mold plate with the same shape as the lower mold plate is used to press and mold it with a pressure of 1.0 MPa; the upper mold plate is removed, the second layer of aluminum or aluminum alloy powder is laid, and the upper mold plate is used to press and mold it with a pressure of 45 MPa to obtain a layered gradient Al-Al matrix composite material blank.

[0048] Step 5: Pressureless sintering: Place the pressed blank into a sintering furnace, heat it to 650℃, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace.

[0049] Step 6: Thermal densification treatment: Place the blank after pressureless sintering in a mold, heat it to 500℃ and apply a pressure of 20MPa, keep it at the temperature and pressure for 0.2h, and air cool it to room temperature to obtain a layered gradient Al-Al matrix composite part.

[0050] Example 3

[0051] A layered gradient Al-Al based composite material includes: a first layer of powder being a ceramic-reinforced aluminum-based composite material, and a second layer of powder being aluminum or an aluminum alloy, wherein the volume ratio of the first layer to the second layer is 1:8.

[0052] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0053] Step 1: Composition Design of Layered Gradient Al-Al Matrix Composite: The first layer of the powdered ceramic reinforced aluminum matrix composite consists of aluminum matrix powder A, alloy element powder B, and ceramic powder C. Aluminum matrix powder A is pure aluminum powder; alloy element powder B includes Si and Cu; ceramic powder C is selected from one or more of B4C, SiC, and Al2O3. The average particle size of aluminum matrix powder A, alloy element powder B, and ceramic powder C is 30 μm. The composition and mass percentage of the first layer of ceramic reinforced aluminum matrix composite are: Si: 10.5%, Cu: 2.0%, Al2O3: 18%, with the balance being Al. The composition and mass percentage of the second layer of aluminum alloy are: Si: 10.5%, Cu: 2.0%, with the balance being Al.

[0054] Step 2: Preparation of the first layer of powder: Add aluminum matrix powder, alloy element powder and ceramic powder to a high-energy ball mill in a certain proportion and carry out a two-stage ball milling process. In the first stage of ball milling, the ball-to-material ratio is 1:1, the ball mill speed is 300 r / min, and the ball milling time is 0.5 h. In the second stage of ball milling, after the first stage of ball milling is completed, add grinding balls to the ball mill to make the ball-to-material ratio 10:1, the ball mill speed is 120 r / min, and the ball milling time is 1.5 h.

[0055] Step 3: Preparation of the second layer of powder: Add the second layer of powder to a high-energy ball mill and carry out the ball milling and mixing process. The ball-to-powder ratio is 1:1, the speed of the ball mill is 250 r / min, and the ball milling time is 1.5 h.

[0056] Step 4: Compression molding: The first layer of ceramic-reinforced aluminum matrix composite powder is evenly spread on the lower mold plate, and the upper mold plate with the same shape as the lower mold plate is used to press and mold it with a pressure of 0.9MPa; the upper mold plate is removed, the second layer of aluminum or aluminum alloy powder is spread, and the upper mold plate is used to press and mold it with a pressure of 48MPa to obtain a layered gradient Al-Al matrix composite material blank.

[0057] Step 5: Pressureless sintering: Place the pressed blank into a sintering furnace, heat it to 600℃, hold it at that temperature for 2.5 hours, and then cool it to room temperature with the furnace.

[0058] Step 6: Thermal densification treatment: Place the blank after pressureless sintering in a mold, heat it to 480℃ and apply a pressure of 25MPa, keep it at the temperature and pressure for 0.2h, and air cool it to room temperature to obtain a layered gradient Al-Al matrix composite part.

[0059] Example 4

[0060] A layered gradient Al-Al based composite material includes: a first layer being a ceramic-reinforced aluminum-based composite material, and a second layer being aluminum or an aluminum alloy, wherein the volume ratio of the first layer to the second layer is 1:7.

[0061] A method for preparing a layered gradient Al-Al based composite material includes the following steps:

[0062] Step 1: Composition Design of Layered Gradient Al-Al Matrix Composite: The first layer of the powdered ceramic reinforced aluminum matrix composite consists of aluminum matrix powder A, alloy element powder B, and ceramic powder C. Aluminum matrix powder A is pure aluminum powder; alloy element powder B includes Si and Cu; ceramic powder C is selected from one or more of B4C, SiC, and Al2O3. The average particle size of aluminum matrix powder A, alloy element powder B, and ceramic powder C is 25 μm. The composition and mass percentage of the first layer of ceramic reinforced aluminum matrix composite are: Si: 9.0%, Cu: 2.5%, B4C: 6%, Al2O3: 10%, with the balance being Al. The composition and mass percentage of the second layer of aluminum alloy are: Si: 9.0%, Cu: 2.5%, with the balance being Al.

[0063] Step 2: First layer powder preparation: Aluminum matrix powder, alloy element powder and ceramic powder are added to a high-energy ball mill in proportion and a two-stage ball milling process is carried out. In the first stage of ball milling, the ball-to-material ratio is 1:1, the ball mill speed is 280 r / min, and the ball milling time is 0.6 h. In the second stage of ball milling, after the first stage of ball milling is completed, grinding balls are added to the ball mill to make the ball-to-material ratio 10:1, the ball mill speed is 100 r / min, and the ball milling time is 1.5 h.

[0064] Step 3: Preparation of the second layer of powder: Add the second layer of powder to a high-energy ball mill and carry out the ball milling and mixing process. The ball-to-powder ratio is 1:1, the speed of the ball mill is 200 r / min, and the ball milling time is 1.8 h.

[0065] Step 4: Compression molding: The first layer of ceramic-reinforced aluminum matrix composite powder is evenly laid on the lower mold plate, and the upper mold plate with the same shape as the lower mold plate is used to press and mold it with a pressure of 0.9MPa; the upper mold plate is removed, the second layer of aluminum or aluminum alloy powder is laid, and the upper mold plate is used to press and mold it with a pressure of 50MPa to obtain a layered gradient Al-Al matrix composite material blank.

[0066] Step 5: Pressureless sintering: Place the pressed blank into a sintering furnace, heat it to 600℃, hold it at that temperature for 3 hours, and then cool it to room temperature with the furnace.

[0067] Step 6: Thermal densification treatment: Place the blank after pressureless sintering in a mold, heat it to 460℃ and apply a pressure of 15MPa, keep it at the temperature and pressure for 0.5h, and air cool it to room temperature to obtain a layered gradient Al-Al based composite material part.

[0068] Comparative Example 1

[0069] The difference between Comparative Example 1 and Example 1 is the composition design of the layered gradient Al-Al matrix composite material. In this comparative example, the powders for the first layer of ceramic-reinforced aluminum matrix composite material and the second layer of aluminum or aluminum alloy are both selected from aluminum matrix powders, and the rest is the same as in Example 1.

[0070] Comparative Example 2

[0071] The difference between Comparative Example 2 and Example 1 is the composition design of the layered gradient Al-Al matrix composite material. In this comparative example, the powders of the first layer of ceramic-reinforced aluminum matrix composite material and the second layer of aluminum or aluminum alloy are both selected from aluminum matrix powder and elemental alloy powder, with the following composition and mass percentage: Si: 7.5%, Cu: 3.0%, and the balance being Al. The rest is the same as in Example 1.

[0072] Comparative Example 3

[0073] The difference between Comparative Example 3 and Example 1 is the preparation of the first layer of powder. Aluminum matrix powder, alloy element powder, and ceramic powder were added to a high-energy ball mill in a specific ratio, along with grinding balls at a ball-to-powder ratio of 1:1. The ball mill rotated at 350 r / min for 2.5 h to obtain the first layer of powder. The rest of the process was the same as in Example 1.

[0074] Comparative Example 4

[0075] Comparative Example 4 differs from Example 1 in that it was molded. The first layer of ceramic-reinforced aluminum matrix composite powder and the second layer of aluminum or aluminum alloy powder were uniformly laid in a mold according to volume ratio, and then pressed under a pressure of 50 MPa to obtain a layered gradient Al-Al matrix composite preform. The rest was the same as in Example 1.

[0076] The table below shows a comparison of the mechanical properties, density, and other comprehensive results of the layered gradient Al-Al based composite materials prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention. The results are shown in Table 1.

[0077] Table 1. Performance data of the materials prepared in Examples 1-4 and Comparative Examples 1-4

[0078]

[0079]

[0080] As can be seen from Table 1, the Al-Al based composite materials obtained in Examples 1-4 all exhibit high hardness and strength, indicating that the composition design, powder preparation, pressureless sintering, and thermal densification processes of the composite materials are reasonable and the technical solutions are feasible. Compared to Example 1, in Comparative Example 1, the powders for the first layer ceramic-reinforced aluminum matrix composite material and the second layer aluminum or aluminum alloy were both selected from aluminum matrix powder. Because no alloying element powder or ceramic powder was added, the material strength and hardness were lower, and its high-temperature resistance was poor. Compared to Example 1, in Comparative Example 2, the powders for the first layer ceramic-reinforced aluminum matrix composite material and the second layer aluminum or aluminum alloy were both selected from aluminum matrix powder and elemental alloy powder. No ceramic phase components were added, significantly reducing the high-temperature resistance of the composite material. Compared to Example 1, in Comparative Example 3, the high-energy ball milling step for the first layer of powder, due to the use of high-speed ball milling, increased the specific surface area of ​​the powder, increased the proportion of aluminum oxide film, weakened the contact between powders, and significantly hindered metallurgical bonding, resulting in a substantial impact on the material's density, strength, and hardness. Compared with Example 1, in Comparative Example 4, the compression molding step is omitted because the low-pressure molding process of the first layer of ceramic-reinforced aluminum matrix composite powder is eliminated. The first layer of powder and the second layer of powder are evenly laid in the mold according to the volume ratio and then subjected to one-time high-pressure molding. This results in incomplete filling of the lower mold recess, low interface bonding strength, and low density of the layered gradient Al-Al matrix composite material.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a layered gradient Al-Al based composite material, characterized in that, Includes the following steps: (1) The components and mass percentages are Si 7.5%-10.5%, Cu 2.0%-3.5%, ceramic powder 6%-18%, and the balance is Al. The components are prepared and mixed to obtain ceramic-reinforced aluminum matrix composite powder with an average particle size of 15-30 μm. The preparation and mixing method is as follows: aluminum matrix powder, alloy element powder and ceramic powder are prepared in proportion. Then, the prepared raw material powder is added to a high-energy ball mill and mixed in two stages. The ball-to-material ratio of the first stage of ball milling is 1:(0.8-1.2), the speed of the ball mill is 250-300 r / min, and the ball milling time is 0.5-1 h. The ball-to-material ratio of the second stage of ball milling is (8-12):1, the speed of the ball mill is 100-150 r / min, and the ball milling time is 1-1.5 h. After ball milling and mixing, ceramic-reinforced aluminum matrix composite powder is obtained. (2) Pure aluminum powder or aluminum alloy powder with a composition and mass percentage of Si 7.5%-10.5%, Cu 2.0%-3.5% and the balance Al is used as the matrix layer powder, and the average particle size of the matrix layer powder is 15-30 μm. (3) The ceramic-reinforced aluminum matrix composite powder and the matrix layer powder are molded in a volume ratio of 1:(5-8) to obtain a composite material blank; the molding method is as follows: First, the ceramic-reinforced aluminum matrix composite powder obtained in step (1) is laid on the lower template of the molding die, and the upper template is used to press it with a pressure of 0.8-1.0MPa; then, the upper template is removed, and the matrix layer powder obtained in step (2) is laid on the pressed ceramic-reinforced aluminum matrix composite powder. After laying, the upper die is used to press it with a pressure of 45-50MPa to obtain a composite material blank; (4) The composite material blank is subjected to pressureless sintering treatment; (5) The composite material blank after pressureless sintering is subjected to thermal densification treatment to obtain the layered gradient Al-Al based composite material.

2. The method for preparing a layered gradient Al-Al based composite material according to claim 1, characterized in that, The pressureless sintering process in step (4) is carried out at a temperature of 600-650℃ and a sintering time of ≥2 hours.

3. The method for preparing a layered gradient Al-Al based composite material according to claim 1, characterized in that, The thermal densification process described in step (5) is as follows: the composite material blank after pressureless sintering is placed in a mold, heated to 450-500℃, and then a pressure of 15-25MPa is applied. The temperature and pressure are maintained for 0.2-0.5h, and the layered gradient Al-Al based composite material is obtained after cooling.

4. The layered gradient Al-Al based composite material prepared by the preparation method according to any one of claims 1-3, characterized in that, The material comprises a matrix layer and a reinforcing layer. The matrix layer is made of pure aluminum or an aluminum alloy, and the composition and mass percentage of the aluminum alloy are: Si 7.5%-10.5%, Cu 2.0%-3.5%, with the balance being Al. The reinforcing layer is a ceramic-reinforced aluminum matrix composite material, and its composition and mass percentage are: Si 7.5%-10.5%, Cu 2.0%-3.5%, ceramic powder 6%-18%, with the balance being Al.

5. The layered gradient Al-Al based composite material according to claim 4, characterized in that, The ceramic powder is one or more of B4C, SiC, and Al2O3, and the average particle size of the ceramic powder is 15-30 μm.

6. The layered gradient Al-Al based composite material according to claim 4, characterized in that, The interfacial bonding strength between the matrix layer and the reinforcing layer is >500MPa, and the tensile strength and yield strength of the material are >520MPa and >405MPa.

7. The application of the layered gradient Al-Al based composite material according to any one of claims 4-6 in automobiles.

Images