Ultrahigh-rigidity magnesium-based composite material as well as preparation method and application thereof

Abstract

The invention provides an ultrahigh-rigidity magnesium-based composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing aluminum oxide ceramic slurry into a ceramic preform by adopting a freezing casting method; and a vacuum pressure infiltration method is adopted for infiltrating magnesium alloy into the ceramic prefabricated body, and the ultrahigh-rigidity magnesium-based composite material is prepared. According to the ultrahigh-rigidity magnesium-based composite material and the preparation method and application thereof, the same mechanical property as that of a traditional aluminum alloy component is guaranteed, and meanwhile the ultrahigh-rigidity magnesium-based composite material is lighter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, in particular to a super-high-rigidity magnesium-based composite material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous development of application requirements, the lightweight of load becomes an urgent common problem to be solved in the development process. The traditional aluminum alloy components have approached the performance limit. From material performance to part manufacturing process, the potential for further improvement is almost exhausted. And with the development of task requirements, the contradiction between the traditional aluminum alloy material and the lightweight, high reliability technology requirements of aerospace load is becoming increasingly acute. Magnesium alloy, as the metal structural material with the smallest density that can be currently engineered, also has the advantages of high specific strength, high specific modulus, damping vibration, electromagnetic shielding, easy processing and forming, and easy recycling. By using magnesium alloy instead of aluminum alloy, further weight reduction of the component can be achieved, and the super-high-rigidity magnesium-based material (elastic modulus ≥ 90 GPa, tensile strength ≥ 385 MPa, yield strength ≥ 330 MPa, and elongation after fracture ≥ 1%) exhibits unique advantages in harsh vibration and impact environments, while further reducing the weight, a high safety stress coefficient can be achieved. SUMMARY

[0003] Based on the technical problems existing in the background art, the present application proposes a super-high-rigidity magnesium-based composite material and a preparation method and application thereof, which can ensure the same mechanical properties as traditional aluminum alloy components while having a lighter weight.

[0004] The preparation method of the super-high-rigidity magnesium-based composite material proposed by the present application comprises the following steps:

[0005] S1, an alumina ceramic slurry is used to prepare a ceramic preform by a freeze casting method;

[0006] S2, a magnesium alloy is infiltrated into the ceramic preform by a vacuum pressure infiltration method to obtain the super-high-rigidity magnesium-based composite material.

[0007] In the present application, a super-high-rigidity magnesium-based composite material is obtained by a method combining freeze casting and vacuum pressure infiltration, which achieves the weight reduction target while significantly improving the safety stress coefficient.

[0008] Preferably, step S1 specifically comprises:

[0009] S11, the alumina ceramic slurry is placed in a mold and frozen, and a frozen green body is obtained after demolding;

[0010] S12, after vacuum freeze-drying of the frozen green body, sintering is performed to obtain the ceramic preform.

[0011] Preferably, in step S11, the alumina ceramic slurry is obtained by ball milling 100 parts of alumina powder, 1-10 parts of sintering aid and 0.5-2 parts of dispersant;

[0012] The freezing temperature is -10℃ to -80℃.

[0013] Preferably, the alumina powder is alumina powder grafted with sulfonic acid-based silane coupling agent; the sintering aid is at least one of yttrium oxide, zirconium oxide, magnesium oxide, silicon oxide or titanium oxide; and the dispersant is ammonium ion surfactant, preferably at least one of cetyltrimethylammonium bromide, polyacrylammonium or tetramethylammonium hydroxide.

[0014] In the present application, the alumina powder is modified by sulfonic acid-based silane coupling agent, and the electrostatic adsorption between ammonium ion surfactant and sulfonic acid group is utilized, thereby effectively improving the dispersion uniformity of the alumina powder in the alumina ceramic slurry, ensuring the porous structure and strength performance of the ceramic preform, and being helpful to the formation of the subsequent ultra-high stiffness magnesium-based composite material.

[0015] Preferably, in step S12, the vacuum freezing drying is performed at a vacuum degree of 10 Pa to 30 Pa and a temperature of -30℃ to -50℃ for 12 h to 36 h.

[0016] The sintering comprises: heating from room temperature to 200℃ to 400℃ at a heating rate of 1℃ / min to 5℃ / min and holding for 20 min to 1 h; then heating to 550℃ to 600℃ at a heating rate of 5℃ / min to 10℃ / min and holding for 0.5 h to 2 h; and then heating to 1000℃ to 1400℃ at a heating rate of 5℃ / min to 10℃ / min and holding for 1 h to 5 h.

[0017] Preferably, step S2 specifically comprises:

[0018] S21, heating and melting the magnesium alloy to obtain a magnesium alloy melt;

[0019] S22, immersing the ceramic preform in the magnesium alloy melt, holding and pressurizing, and then cooling to obtain the ultra-high stiffness magnesium-based composite material.

[0020] Preferably, the magnesium alloy is AZ91 magnesium alloy.

[0021] The heating and melting temperature is 720℃ to 760℃, and the heating rate is 1℃ / min to 10℃ / min.

[0022] Preferably, in step S22, the holding and pressurizing temperature is 720℃ to 760℃, the pressure is 1MPa to 2MPa, and the time is 1h to 2h.

[0023] The application further provides the super-high-rigidity magnesium-based composite material prepared by the preparation method.

[0024] The application further provides application of the super-high-rigidity magnesium-based composite material in preparation of a frame / support member.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] (1) The super-high-rigidity magnesium-based composite material member (frame) has a maximum stress of 12.99 MPa under acceleration overload, a maximum stress of 17.86 MPa under sinusoidal vibration, a maximum stress of 115.14 MPa under random vibration (3σ), and a stress safety factor of 2.4, which is much greater than that of an aluminum alloy composite material member (frame, safety factor 1.5), and the weight is reduced by 20%.

[0027] (2) The super-high-rigidity magnesium-based composite material member (support seat) has a maximum stress of 19.34 MPa under acceleration overload, a maximum stress of 15.19 MPa under sinusoidal vibration, a maximum stress of 35.03 MPa under random vibration (3σ), and a stress safety factor of 8, which is much greater than that of an aluminum alloy composite material member (frame, safety factor 1.5), and the weight is reduced by 20%.

[0028] (3) The super-high-rigidity magnesium-based composite material frame / support seat is verified by random vibration, sinusoidal vibration, impact test, and acceleration test. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a physical diagram of the super-high-rigidity magnesium-based composite material frame member described in Example 1;

[0030] Figure 2 is a mechanical simulation diagram of the super-high-rigidity magnesium-based composite material frame member described in Example 1;

[0031] Figure 3 is a mechanical simulation diagram of the super-high-rigidity magnesium-based composite material seat member described in Example 1. DETAILED DESCRIPTION

[0032] In the following, the technical solutions of the application will be described in detail through specific examples, but it should be clear that these examples are used for illustration, but not to be interpreted as limiting the scope of the application.

[0033] Example 1

[0034] A super-high-rigidity magnesium-based composite material frame member, and a preparation method thereof, comprises the following steps:

[0035] (1) Preparing an alumina ceramic preform:

[0036] First step: Put 100 parts of alumina powder (average particle size of 5 μm), 5 parts of sintering aid (zirconium oxide), 1 part of dispersing agent (cetyl trimethyl ammonium bromide) and 200 parts of deionized water into a corundum ball mill tank by weight parts, the rotation speed of the ball mill is 100 rpm, the ball milling time is 12 h, and a uniformly mixed alumina ceramic slurry is prepared;

[0037] Second step: Put the alumina ceramic slurry into a vacuum box for degassing, and then freeze it in a metal mold corresponding to the frame member, the inner cavity of the metal mold should be slightly larger than the outer envelope size of the actual part, the single side size is at least 6 mm, the freezing temperature is -40℃, and the frozen green body is obtained after demolding;

[0038] Third step: Put the frozen green body into a vacuum freeze dryer, set the vacuum degree in the vacuum freeze dryer to 20 Pa, the freeze drying temperature to -40℃, and the freeze drying time to 24 h, and the ice in the frozen green body sublimates;

[0039] Fourth step: Put the green body after vacuum freeze drying into a heating furnace for sintering, first heat from room temperature to 300℃ at a heating rate of 3℃ / min, keep the temperature for 40 min; then heat to 580℃ at a heating rate of 8℃ / min, keep the temperature for 1 h; finally, heat to 1200℃ at a heating rate of 8℃ / min, keep the temperature for 3 h, and cool to room temperature in the furnace, to obtain an alumina ceramic preform;

[0040] (2) Vacuum infiltration to prepare an ultra-high stiffness magnesium alloy blank:

[0041] First step: Put the AZ91 magnesium alloy raw material into a vacuum heating furnace, vacuumize to a pressure of 20 Pa, then fill in protective gas argon until the pressure is 0.05 MPa, heat at a temperature of 740℃, and a heating rate of 5℃ / min to obtain a magnesium alloy melt;

[0042] Second step: Immerse the alumina ceramic preform in the magnesium alloy melt, keep the heating temperature at 740℃, and at the same time, fill in protective gas argon, keep the pressure at 1.5 MPa, and the time is 1.5 h; reduce the heating temperature to 550℃, take out the infiltrated blank, cool to room temperature in the furnace, and take out the ultra-high stiffness magnesium alloy blank;

[0043] (3) Process the ultra-high stiffness magnesium matrix composite frame member:

[0044] First step: Polish and sand the outer surface of the ultra-high stiffness magnesium alloy blank;

[0045] Second step: using a hard alloy cutter, the rake angle is 25 degrees, the relief angle is slightly larger, the connection of the cutting edge adopts a smooth transition, the tool tip angle is increased, the tool path is processed in a high-speed layered and surrounding manner, the feed speed is 40 m / min, and the rotation speed is 10000 rpm;

[0046] Third step: surface oxidation and oil painting treatment are performed on the super-high-rigidity magnesium alloy blank, so that the super-high-rigidity magnesium matrix composite frame member is obtained.

[0047] Reference Figure 2 According to finite element modeling calculation of related maximum stress, wherein the acceleration: ±X direction 17g, ±Y and ±Z direction 48g; impact 30g, three directions, 11ms; vibration total root mean square value 12g, 3 minutes in each direction; the maximum stress of the super-high-rigidity magnesium matrix composite frame member is 12.99MPa, the maximum stress of the sinusoidal vibration is 17.86MPa, the maximum stress of the random vibration (3σ) is 115.14MPa, and the stress safety factor is 2.4.

[0048] Example 2

[0049] A super-high-rigidity magnesium matrix composite seat member, a preparation method thereof comprises:

[0050] (1) preparing an alumina ceramic preform:

[0051] First step: 100 parts of alumina powder (average particle size 5μm), 5 parts of sintering aid (zirconium oxide), 1 part of dispersing agent (cetyltrimethylammonium bromide) and 200 parts of deionized water are put into a corundum ball mill tank, the rotation speed of the ball mill is 100rpm, and the ball milling time is 12h, so as to prepare uniformly mixed alumina ceramic slurry;

[0052] Second step: the alumina ceramic slurry is placed in a vacuum box for degassing, and then placed in a metal mold corresponding to the seat member for freezing, the inner cavity of the metal mold should be slightly larger than the outer envelope size of the actual part, the single-side size is at least 6mm larger, the freezing temperature is-40℃, and the frozen green body is obtained after demolding;

[0053] Third step: the frozen green body is placed in a vacuum freeze dryer, the vacuum degree in the vacuum freeze dryer is set to 20Pa, the freeze-drying temperature is-40℃, and the freeze-drying time is 24h, so that the ice in the frozen green body is sublimated;

[0054] Fourth step: the green body after vacuum freeze-drying is placed in a heating furnace for sintering, first heated from room temperature to 300℃ at a rate of 3℃ / min, and the holding time is 40min; then heated to 580℃ at a rate of 8℃ / min, and the holding time is 1h; finally, heated to 1200℃ at a rate of 8℃ / min, and the holding time is 3h, and the furnace is cooled to room temperature, to obtain an alumina ceramic preform;

[0055] (2) Preparation of an ultra-high stiffness magnesium alloy blank by vacuum infiltration:

[0056] First step: the AZ91 magnesium alloy raw material is placed in a vacuum heating furnace, vacuumized to a pressure of 20Pa, and then filled with protective gas argon until the pressure is 0.05MPa, and the heating temperature is 740℃, and the heating rate is 5℃ / min, to obtain a magnesium alloy melt;

[0057] Second step: the alumina ceramic preform is immersed in the magnesium alloy melt, the heating temperature is kept at 740℃, and the protective gas argon is filled, the pressure is 1.5MPa, and the time is 1.5h; the heating temperature is reduced to 550℃, the infiltrated blank is taken out, and the ultra-high stiffness magnesium alloy blank is taken out and cooled to room temperature in the furnace;

[0058] (3) Processing of an ultra-high stiffness magnesium matrix composite frame member:

[0059] First step: the ultra-high stiffness magnesium alloy blank is polished and sanded on the outer surface;

[0060] Second step: a hard alloy tool is used, the rake angle is 25 degrees, the relief angle is slightly larger, the connection of the cutting edge is smooth transition, the tool tip angle is increased, the feed speed is 40m / min, and the rotation speed is 10000rpm;

[0061] Third step: the ultra-high stiffness magnesium alloy blank is surface oxidized and painted, to obtain the ultra-high stiffness magnesium matrix composite frame member.

[0062] Reference Figure 3 According to the finite element modeling calculation of the related maximum stress, the acceleration overload maximum stress of the above ultra-high stiffness magnesium matrix composite seat member is 19.34MPa, the sinusoidal vibration maximum stress is 15.19MPa, the random vibration (3σ) maximum stress is 35.03MPa, and the stress safety factor is 8.

[0063] Example 3

[0064] A super-high-rigidity magnesium-based composite frame member was prepared according to the method of Example 1, except that in the preparation of the alumina ceramic preform, alumina powder (average particle size 5 μm) was first uniformly dispersed in water by ultrasonic treatment, then 3-(trihydroxysilyl)-propane sulfonic acid was added, the amount of 3-(trihydroxysilyl)-propane sulfonic acid being 5% by weight of the alumina powder, then sodium hydroxide solution was added to adjust the pH value to 6, and the mixture was stirred at 60°C for 6 h, centrifuged, washed, and dried to obtain alumina powder grafted with sulfonic acid group-containing silane coupling agent; then the alumina powder grafted with sulfonic acid group-containing silane coupling agent was used instead of alumina powder and sintering aids (zirconia), dispersing agent (cetyltrimethylammonium bromide), and deionized water in the corundum ball mill pot.

[0065] According to the test conditions described in Example 1, the maximum stress of the above super-high-rigidity magnesium-based composite frame member under acceleration overload was 10.24 MPa, the maximum stress under sinusoidal vibration was 14.35 MPa, the maximum stress under random vibration (3σ) was 101.29 MPa, and the stress safety factor was 3.3.

[0066] Example 4

[0067] A super-high-rigidity magnesium-based composite seat member was prepared according to the method of Example 2, except that in the preparation of the alumina ceramic preform, alumina powder (average particle size 5 μm) was first uniformly dispersed in water by ultrasonic treatment, then 3-(trihydroxysilyl)-propane sulfonic acid was added, the amount of 3-(trihydroxysilyl)-propane sulfonic acid being 5% by weight of the alumina powder, then sodium hydroxide solution was added to adjust the pH value to 6, and the mixture was stirred at 60°C for 6 h, centrifuged, washed, and dried to obtain alumina powder grafted with sulfonic acid group-containing silane coupling agent; then the alumina powder grafted with sulfonic acid group-containing silane coupling agent was used instead of alumina powder and sintering aids (zirconia), dispersing agent (cetyltrimethylammonium bromide), and deionized water in the corundum ball mill pot.

[0068] According to the test conditions described in Example 1, the maximum stress of the above super-high-rigidity magnesium-based composite seat member under acceleration overload was 17.07 MPa, the maximum stress under sinusoidal vibration was 12.33 MPa, the maximum stress under random vibration (3σ) was 31.24 MPa, and the stress safety factor was 9.2.

[0069] Comparative Example 1

[0070] A kind of super-high rigidity magnesium-based composite frame member, its preparation method refers to example 1, except that in preparation alumina ceramic preform, first, alumina powder (average particle size is 5 μm) is added in water ultrasonic dispersion uniformity, 3-(trihydroxy silicon group)-propane sulfonic acid is added, the amount of 3-(trihydroxy silicon group)-propane sulfonic acid is 5wt% of alumina powder, then sodium hydroxide solution is added to adjust pH value to 6, stirring is carried out at 60 DEG C for 6h, centrifugal washing, drying, and the alumina powder of surface grafting sulfonic acid group silane coupling agent is obtained;After that, the alumina powder of surface grafting sulfonic acid group silane coupling agent is placed in corundum ball mill pot instead of alumina powder and sintering aid (zirconium oxide), dispersing agent (sodium polymethacrylate) and deionized water are ball milled.

[0071] According to the test conditions described in example 1, the maximum stress of the above-mentioned super-high rigidity magnesium-based composite frame member is 13.13 MPa under acceleration overload, the maximum stress is 17.42 MPa under sinusoidal vibration, the maximum stress is 117.37 MPa under random vibration (3σ), and the stress safety factor is 2.3.

[0072] Comparative example 2

[0073] A kind of super-high rigidity magnesium-based composite seat member, its preparation method refers to example 2, except that in preparation alumina ceramic preform, first, alumina powder (average particle size is 5 μm) is added in water ultrasonic dispersion uniformity, 3-(trihydroxy silicon group)-propane sulfonic acid is added, the amount of 3-(trihydroxy silicon group)-propane sulfonic acid is 5wt% of alumina powder, then sodium hydroxide solution is added to adjust pH value to 6, stirring is carried out at 60 DEG C for 6h, centrifugal washing, drying, and the alumina powder of surface grafting sulfonic acid group silane coupling agent is obtained;After that, the alumina powder of surface grafting sulfonic acid group silane coupling agent is placed in corundum ball mill pot instead of alumina powder and sintering aid (zirconium oxide), dispersing agent (sodium polymethacrylate) and deionized water are ball milled.

[0074] According to the test conditions described in example 1, the maximum stress of the above-mentioned super-high rigidity magnesium-based composite seat member is 20.09 MPa under acceleration overload, the maximum stress is 14.87 MPa under sinusoidal vibration, the maximum stress is 36.93 MPa under random vibration (3σ), and the stress safety factor is 7.6.

[0075] The above-mentioned is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art in the technical range disclosed by the present application, according to the technical scheme and the inventive concept of the present application, equivalent replacement or change, should be covered in the protection scope of the present application.

Claims

1. A method of producing an ultra-high stiffness magnesium-based composite material, characterized by, The method comprises the following steps: S1, preparing a ceramic preform by using a freeze casting method; S2, infiltrating a magnesium alloy into the ceramic preform by using a vacuum pressure infiltration method to obtain the super-high-rigidity magnesium matrix composite material.

2. The method of claim 1, wherein the magnesium-based composite material has an ultra-high stiffness. The step S1 specifically comprises: S11, placing the alumina ceramic slurry into a mold for freezing, and obtaining a frozen green body after demolding; S12, vacuum freeze-drying the frozen green body, and then sintering to obtain the ceramic preform.

3. The method of claim 2, wherein the magnesium-based composite material has an ultra-high stiffness. In the step S11, the alumina ceramic slurry is obtained by ball-milling alumina powder 100 parts, sintering aid 1-10 parts and dispersant 0.5-2 parts uniformly; The freezing temperature is-10℃ to-80℃.

4. The method of claim 3, wherein the magnesium-based composite material has an ultra-high stiffness. The alumina powder is alumina powder with surface grafted sulfonic acid silane coupling agent; the sintering aid is at least one of yttrium oxide, zirconium oxide, magnesium oxide, silicon oxide or titanium oxide; and the dispersant is ammonium ion surfactant, preferably at least one of cetyltrimethylammonium bromide, polyacrylammonium or tetramethylammonium hydroxide.

5. The method of producing an ultra-high stiffness magnesium matrix composite according to any one of claims 2 to 4, characterized in that, In the step S12, the vacuum degree of the vacuum freeze-drying is 10 Pa to 30 Pa, the temperature is-30℃ to-50℃, and the time is 12 h to 36 h; The sintering comprises: heating from room temperature to 200℃ to 400℃ at a heating rate of 1℃ / min to 5℃ / min, and holding for 20 min to 1 h; then heating to 550℃ to 600℃ at a heating rate of 5℃ / min to 10℃ / min, and holding for 0.5 h to 2 h; and then heating to 1000℃ to 1400℃ at a heating rate of 5℃ / min to 10℃ / min, and holding for 1 h to 5 h.

6. The method of producing ultra-high stiffness magnesium matrix composites according to any one of claims 1 to 5, characterized in that, The step S2 specifically comprises: S21, heating and melting the magnesium alloy to obtain a magnesium alloy melt; S22, immersing the ceramic preform into the magnesium alloy melt, holding and pressurizing, and then cooling to obtain the super-high-rigidity magnesium matrix composite material.

7. The method of claim 6, wherein the magnesium-based composite material has an ultra-high stiffness. In the step S21, the magnesium alloy is AZ91 magnesium alloy; The heating and melting temperature is 720℃ to 760℃, and the heating rate is 1℃ / min to 10℃ / min.

8. The method for preparing the ultra-high stiffness magnesium-based composite material according to claim 6 or 7, characterized in that, In the step S22, the holding and pressurizing temperature is 720℃ to 760℃, the pressure is 1 MPa to 2 MPa, and the time is 1 h to 2 h.

9. A super-high-rigidity magnesium matrix composite material prepared by the preparation method of any one of claims 1-8.

10. Use of the super-high-rigidity magnesium matrix composite material of claim 9 in preparing a frame / seat component.

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