Ultrahigh-strength anti-fatigue ceramic particle aluminum-based composite material and preparation method thereof

Abstract

The invention belongs to the field of aluminum-based composite materials, and particularly relates to an ultrahigh-strength anti-fatigue ceramic particle aluminum-based composite material and a preparation method thereof.The preparation method comprises the steps that magnesium hydroxide whiskers are prepared, and titanium and the magnesium hydroxide whiskers are ground and mixed; adding aluminum powder and boron powder under the oxygen-free condition, uniformly mixing, and pressing into a block to obtain a blank; carrying out heat treatment on the blank, softening and generating pores to obtain a precursor; and the precursor is added into molten aluminum alloy, and the ultrahigh-strength anti-fatigue ceramic particle aluminum-based composite material is prepared. According to the ultrahigh-strength anti-fatigue ceramic particle aluminum-based composite material, TiB2 particles are uniformly distributed and are well combined with a matrix, and the elastic modulus of the composite material is gt; the tensile strength is gt; the elongation at break is gt under the pressure of 660 MPa; 8%, fatigue strength gt; the composite material has excellent comprehensive performance under the pressure of 280 MPa.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based composite materials, specifically relating to an ultra-high strength fatigue-resistant ceramic particle aluminum-based composite material and its preparation method. Background Technology

[0002] Aluminum-based composites have attracted widespread attention as structural materials due to their excellent specific strength, stiffness, and wear resistance. TiB2, with its high hardness and non-reactive interface with the metal matrix, is a commonly used reinforcing particle in aluminum-based composites. In-situ synthesis refers to the method of generating reinforcing particles in situ within an aluminum matrix under certain conditions through chemical reactions between elements or between elements and compounds. In-situ synthesis offers advantages such as simple production processes, low production costs, ease of large-scale mass production, and the ability to manufacture products with complex shapes. The TiB2 particles synthesized in situ in aluminum-based composites have micro- and nano-sized particle sizes, which is beneficial for improving the mechanical properties of the composite material. However, due to the influence of particle surface energy, nano-sized TiB2 particles are prone to agglomeration, resulting in composite materials with high strength but poor plasticity. Under alternating pressure, after a period of time, microcracks can form in metal materials or some industrial products and parts at locations of stress concentration, particle agglomeration, or casting defects caused by different casting methods. These cracks gradually propagate and lead to fracture. Improving the dispersibility and compatibility of TiB2 particles with the matrix, and reducing crack initiation and propagation, are key to enhancing the strength and fatigue resistance of aluminum matrix composites.

[0003] For example, Chinese patent CN107723526A discloses a corrosion-resistant rare-earth aluminum alloy and its preparation method. However, due to the unstable morphology of the reinforcing phase, the precipitated phase coarsens during long-term service, thereby reducing corrosion resistance and mechanical properties. Chinese patent CN104073674A discloses a method for preparing a graphene-aluminum-based composite material. Aluminum alloy powder is placed in a ball mill jar, evacuated, and then filled with a protective gas. Graphene and aluminum metal powders are then placed in the ball mill jar and ball-milled to obtain a composite powder, which is then cold-pressed into a preform. Aluminum liquid is obtained through melting and then impregnated into the gaps between the preforms to obtain the graphene-aluminum-based composite material. This method has difficulty controlling the dispersion of the reinforcing phase in the composite material, resulting in uneven performance across different parts of the workpiece. Chinese patent CN101173331A discloses a method for preparing aluminum-based composite materials. The method involves mixing molten aluminum (1300-1700℃) with KBF4, K2TiF6, and TiO2 under mechanical stirring, followed by cooling and then heating to remove byproducts, yielding an aluminum-based composite material precursor. This precursor is then kept in a molten state and mixed with magnesium and copper. However, this in-situ method for generating reinforcing particles suffers from excessively high aluminum melt temperatures, leading to alloy element burn-off, and the mechanical stirring process introduces impurities. Summary of the Invention

[0004] To address the problems of poor dispersibility and compatibility with the matrix of TiB2 particles, resulting in poor toughness and fatigue resistance in existing technologies, this invention mainly provides a method for preparing ultra-high strength, fatigue-resistant ceramic particle aluminum-based composite materials, and the composite material obtained by this method. The technical solution is as follows: A method for preparing an ultra-high strength fatigue-resistant ceramic particle aluminum-based composite material includes the following steps: preparing magnesium hydroxide whiskers, grinding and mixing titanium and magnesium hydroxide whiskers; adding aluminum powder and boron powder under oxygen-free conditions, mixing evenly, and pressing into blocks to obtain a blank; heat-treating the blank to soften it and generate pores to obtain a precursor; adding the precursor to molten aluminum alloy to obtain the ultra-high strength fatigue-resistant ceramic particle aluminum-based composite material.

[0005] Furthermore, the mass ratio of titanium to boron powder is 1:0.5~0.7; the mass ratio of aluminum powder to boron powder is 1:0.25~0.75; and the molar ratio of magnesium hydroxide whiskers to titanium is 1:4~20.

[0006] Furthermore, the precursor is heat-treated at 650~750℃ for 4~6 hours, then treated at 1100~1300℃ for 0.5~1 hours, and then mixed with molten aluminum alloy.

[0007] Furthermore, after melting the aluminum alloy, it is poured into a mold, and the precursor is placed in the mold containing the aluminum melt, so that the aluminum melt completely covers the blank. After cooling, an intermediate is obtained; the intermediate is placed in the molten aluminum alloy to obtain an ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

[0008] Furthermore, the aluminum alloy is a 7-series Al-Zn-Mg-Cu alloy, including 7075Al, 7050Al, 7A04, 7136, 7185 and 7056Al, etc.

[0009] Furthermore, this includes the following steps: a. Preparation of magnesium hydroxide whiskers; Take titanium and magnesium hydroxide whiskers, add alcohol and grind and mix at a speed of 50~100 rpm for 10~30 min to obtain a mixture; b. Under an argon atmosphere, aluminum powder and boron powder are first ground and dispersed, and then the mixture is added and ground and dispersed to obtain a mixed powder; the mixed powder is pressed into blocks with a relative density of 50-70% to obtain a blank; c. Heat-treat the blank at 350~450℃ for 2~4h to soften the blank and generate pores to obtain a precursor; add the precursor to molten aluminum alloy to obtain an ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

[0010] Further, in step b, aluminum powder and boron powder are ground at 250-350 rpm for 2-3 hours under an argon atmosphere, and then the mixture is added and ground at 100-200 rpm for 0.5-1.5 hours to obtain a mixed powder.

[0011] Furthermore, the preparation of the magnesium hydroxide whiskers includes the following steps: Prepare a sodium carbonate and magnesium sulfate solution. While stirring, add sodium carbonate dropwise to the magnesium sulfate solution and react at 30-50℃ for 0.5-3 hours. Separate and collect the precipitate, wash thoroughly with water to obtain magnesium carbonate whiskers. Disperse the obtained magnesium carbonate whiskers in water and react at 50-65℃ until the solvent evaporates to dryness to obtain magnesium hydroxide whiskers.

[0012] Furthermore, the mass ratio of magnesium sulfate to sodium carbonate is 1:1~2.5; magnesium carbonate and ammonium sulfate are ground and mixed, and then calcined at 480~580℃ for 0.5~2h to obtain magnesium sulfate.

[0013] Furthermore, the mass ratio of magnesium carbonate to ammonium sulfate is 1:2.5~3.

[0014] An ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material prepared by the above method.

[0015] By adopting the above scheme, the method of the present invention has the following advantages: 1. The composite material of the present invention generates TiB2 particle reinforcement in situ within an aluminum matrix. The reinforcement is tightly bonded to the matrix, exhibits strong dispersibility, and has uniform particle size. Fatigue crack propagation is not easily achieved, resulting in high material strength and good fatigue resistance.

[0016] 2. This invention utilizes the pores generated by gas escape during the conversion of magnesium hydroxide to magnesium oxide to increase the porosity of the precursor, which facilitates full contact between molten aluminum, titanium, and boron, promotes uniform distribution of solute atoms, makes the reaction more complete and uniform, reduces agglomeration, and improves the mechanical properties of the material.

[0017] 3. In this invention, magnesium hydroxide whiskers are added to the aluminum base. After losing water and turning into magnesium oxide, the whisker structure can still be retained to a certain extent, which produces crack deflection and crack bridging effects, thereby improving the fracture toughness of the composite material.

[0018] 4. In the second stage of high-temperature treatment of segmented heat treatment, some magnesium is released from the whiskers and forms a magnesium, aluminum and boron bonded reinforcement with aluminum and excess boron. This increases the variety of reinforcements in the matrix and has strong dispersibility, improving the interfacial bonding strength between the reinforcement and the aluminum matrix. The strength and toughness of the material are significantly improved, and the fatigue resistance is excellent.

[0019] 5. In this invention, magnesium carbonate whiskers are first prepared and then hydrated to generate magnesium hydroxide. Compared with magnesium carbonate, magnesium hydroxide is converted to magnesium oxide at a lower temperature, significantly reducing the production cost. The temperature difference between different reaction processes is greater and more controllable.

[0020] 6. This invention mixes raw materials to form a preform, then creates more pores to obtain a precursor. A layer of aluminum is then coated on the surface. The aluminum surface oxidizes to form dense alumina, protecting the internal precursor and preventing the internal titanium and boron from contacting and being contaminated by the external environment. The aluminum-coated precursor can be stored for a long time. When used, the appropriate amount of precursor can be freely selected and applied to different aluminum matrices according to the properties of the material to be prepared, thus broadening its application range. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the elastic modulus of various embodiments; Figure 2 This is a comparison diagram of the yield strength of various embodiments; Figure 3 This is a comparison diagram of the tensile strength of various embodiments; Figure 4 This is a comparison chart of the elongation at break of each embodiment; Figure 5 This is a comparison chart of the fatigue strength of various embodiments.

[0022] Figure 6 This is a schematic diagram of the geometric dimensions of a tensile specimen; Figure 7 This is a schematic diagram of the geometric dimensions of the fatigue specimen. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: (1) Magnesium carbonate and ammonium sulfate were ground and mixed at a mass ratio of 1:2.5, and then calcined at 520°C for 1 h to obtain magnesium sulfate; a sodium carbonate and magnesium sulfate solution was prepared at a mass ratio of 1:1.5, and sodium carbonate was added dropwise to the magnesium sulfate solution while stirring. The reaction was carried out at 40°C for 2 h, the precipitate was separated and collected, and thoroughly washed with water to obtain magnesium carbonate whiskers; the obtained magnesium carbonate whiskers were dispersed in water and reacted at 50°C until the solvent evaporated to dryness to obtain magnesium hydroxide whiskers; (2) Take 2 parts by mass of titanium and 0.2 parts by mass of magnesium hydroxide whiskers, add alcohol and grind and mix at 8 rpm for 20 min to obtain a mixture; under argon atmosphere, grind 2.5 parts by mass of aluminum powder and 1.4 parts by mass of boron powder at 300 rpm for 2-3 h, continue to add the mixture and grind at 150 rpm for 1 h to obtain a mixed powder; press the mixed powder into a block with a relative density of 50% to obtain a blank; (3) Heat-treat the blank at 450℃ for 4 hours to soften the blank and generate pores to obtain the precursor; heat-treat the precursor at 750℃ for 6 hours, and then heat it to 1200℃ and hold it for 0.5 hours to complete the segmented heat treatment. (4) After melting 7075Al, pour it into a mold, place the precursor in the mold containing 7075Al melt, so that the melt completely covers the blank, and obtain the intermediate after cooling; place the intermediate in the molten aluminum alloy to obtain ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

[0025] Example 2: The difference from Example 1 is as follows: (1) Grind and mix magnesium carbonate and ammonium sulfate at a mass ratio of 1:2.5, and then calcine at 520°C for 1 h to obtain magnesium sulfate; prepare a sodium carbonate and magnesium sulfate solution at a mass ratio of 1:1.5, add sodium carbonate dropwise to the magnesium sulfate solution while stirring, react at 40°C for 2 h, separate and collect the precipitate, wash thoroughly with water to obtain magnesium carbonate whiskers; disperse the obtained magnesium carbonate whiskers in water, react at 65°C until the solvent evaporates to dryness to obtain magnesium hydroxide whiskers.

[0026] Example 3: The difference from Example 1 is as follows: (2) Take 2 parts by mass of titanium and 1 part by mass of magnesium hydroxide whiskers and add alcohol to grind and mix at 80 rpm for 20 min to obtain a mixture; under argon atmosphere, grind 2.5 parts by mass of aluminum powder and 1.4 parts by mass of boron powder at 300 rpm for 2-3 h, and continue to add the mixture and grind at 150 rpm for 1 h to obtain a mixed powder; press the mixed powder into a block with a relative density of 50% to obtain a blank.

[0027] Example 4: The difference from Example 1 is as follows: (2) Take 2 parts by mass of titanium and 0.1 parts by mass of magnesium hydroxide whiskers and add alcohol to grind and mix at 80 rpm for 20 min to obtain a mixture; under argon atmosphere, grind 2.5 parts by mass of aluminum powder and 1.4 parts by mass of boron powder at 300 rpm for 2-3 h, and continue to add the mixture and grind at 150 rpm for 1 h to obtain a mixed powder; press the mixed powder into a block with a relative density of 50% to obtain a blank.

[0028] Example 5: The difference from Example 1 is as follows: (2) Take 2 parts by mass of titanium and 0.2 parts by mass of magnesium hydroxide whiskers and add alcohol to grind and mix at 80 rpm for 20 min to obtain a mixture; under argon atmosphere, grind 2.5 parts by mass of aluminum powder and 1 part by mass of boron powder at 300 rpm for 2-3 h, and continue to add the mixture and grind at 150 rpm for 1 h to obtain a mixed powder; press the mixed powder into a block with a relative density of 50% to obtain a blank.

[0029] Example 6: The difference from Example 1 is as follows: (2) Take 2 parts by mass of titanium and 0.2 parts by mass of magnesium hydroxide whiskers and add alcohol to grind and mix at 80 rpm for 20 min to obtain a mixture; under argon atmosphere, grind 2.5 parts by mass of aluminum powder and 1.4 parts by mass of boron powder at 300 rpm for 2-3 h, and continue to add the mixture and grind at 150 rpm for 1 h to obtain a mixed powder; press the mixed powder into a block with a relative density of 70% to obtain a blank.

[0030] Example 7: The difference from Example 1 is as follows: (3) Heat-treat the blank at 350℃ for 2 hours to soften the blank and generate pores to obtain the precursor; heat-treat the precursor at 750℃ for 6 hours, and then heat it to 1200℃ and hold it for 0.5 hours to complete the segmented heat treatment.

[0031] Example 8: The difference from Example 1 is as follows: (3) Heat-treat the blank at 450℃ for 2 hours to soften the blank and generate pores to obtain the precursor; heat-treat the precursor at 750℃ for 6 hours, and then heat it to 1200℃ and hold it for 0.5 hours to complete the segmented heat treatment.

[0032] Example 9: The difference from Example 1 is as follows: (3) Heat-treat the blank at 450℃ for 4 hours to soften the blank and generate pores to obtain the precursor; heat-treat the precursor at 750℃ for 6 hours, and then heat it to 1200℃ and hold it for 1 hour to complete the segmented heat treatment.

[0033] Example 10: The difference from Example 1 is as follows: (3) Heat-treat the preform at 450°C for 4 hours to soften the preform and generate pores to obtain the precursor.

[0034] Example 11: The difference from Example 1 is as follows: (4) The precursor was placed in molten 7050Al alloy to obtain ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

[0035] Example Sample Testing: All embodiments used a 7-series Al-Zn-Mg-Cu alloy as the molten matrix, and the prepared samples contained 5 wt.% TiB2. The aluminum-based composite materials of all embodiments were solution-treated at 480°C for 70 min, then quenched at room temperature, and then aged at 120°C for 20 h, followed by furnace cooling. The methods for testing elastic modulus, yield strength, tensile strength, and elongation at break were as follows: Figure 6 Samples were prepared and tested using a universal testing machine according to GB / T 228.1-2021 standard, with a tensile rate of 1 mm / min. The fatigue performance testing method was as follows: Figure 7 Prepare test specimens and conduct tests according to GB / T 3075-2021 standard, using a stress ratio of 0.5 and a frequency of 10-30Hz. Test one specimen at each stress level until the specimen passes 10. 7 Based on the initial fatigue limit value obtained by the single-point method, the fatigue limit was then accurately determined using the rise-fall method. Since the performance differences between the various embodiments were not significant, five samples were prepared for each embodiment to make the data closer to the actual performance. The results are as follows: From the above table and Figures 1-4It can be seen that the temperature at which magnesium carbonate was converted into magnesium hydroxide whiskers in Example 2 was higher than that in Example 1, and the water evaporated faster. The elastic modulus, yield strength, and tensile strength of the resulting sample were all reduced, as was the fatigue limit. This is likely because the higher temperature and shorter time affected the formation of magnesium hydroxide whiskers. Example 3 added more magnesium hydroxide whiskers, while Example 4 added fewer. The strength of the sample in Example 4 was significantly lower than that in Example 3, especially the fatigue limit, which was reduced by 27 MPa. This indicates that the presence of magnesium oxide whiskers has a significant effect on improving the strength of the material, especially its fatigue resistance. In Example 5, the boron content involved in the reaction was less than that in Example 1. Its yield strength and tensile strength were significantly lower than those in Example 1, with the tensile strength decreasing by 17 MPa, while the fatigue limit only decreased by 5 MPa. This may be because less boron affects the content of the magnesium, aluminum, and boron bonded reinforcement, and the interfacial bonding between the reinforcement and the whiskers and the matrix may also be affected to some extent, but the whisker structure is more preserved. The pressed block in Example 6 had a high relative density and fewer pores within the block itself, resulting in a significant decrease in both the mechanical strength and fatigue limit of the material. When the raw material is softened and pores are generated, the heat treatment temperature and time in Example 7 are lower, and the treatment time in Example 8 is reduced. The mechanical strength and fatigue limit of the samples in both examples are significantly reduced, indicating that more pores are beneficial to the full bonding of raw materials and promote the full reaction. In Example 9, during the segmented heat treatment, the heat treatment time at the high temperature of the second stage is longer, and the strength of the sample increases, but the fatigue limit does not increase but decreases. This indicates that the longer high-temperature heat treatment is beneficial to increasing the content of magnesium, aluminum and boron-bonded reinforcement, but it will affect the retention of whisker structure. In Example 10, no segmented heat treatment is performed, and the sample strength and fatigue limit decrease significantly, indicating that the segmented heat treatment step has a significant effect on improving the strength and fatigue resistance of the sample. In Example 11, no intermediate preparation step is performed, and the mechanical properties of the sample do not change. This indicates that compared with direct preparation, storing the intermediate and then fusing it with the matrix does not affect the mechanical properties of the sample.

[0036] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for preparing an ultra-high-strength, fatigue-resistant ceramic particle aluminum matrix composite material, characterized in that, Includes the following steps: Magnesium hydroxide whiskers were prepared by grinding and mixing titanium and magnesium hydroxide whiskers; aluminum powder and boron powder were added under oxygen-free conditions, and after being mixed evenly, they were pressed into blocks to obtain a blank; the blank was heat-treated to soften it and generate pores to obtain a precursor; the precursor was added to molten aluminum alloy to obtain an ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

2. The method of claim 1, wherein the ceramic particle reinforced aluminum matrix composite material has a tensile strength of 400 MPa or more, an elongation of 1% or more, and a fatigue limit of 200 MPa or more. The mass ratio of titanium to boron powder is 1:0.5~0.7; the mass ratio of aluminum powder to boron powder is 1:0.25~0.75; and the molar ratio of magnesium hydroxide whiskers to titanium is 1:4~20.

3. The method of claim 1, wherein the ceramic particulate reinforced aluminum matrix composite material has a tensile strength of 400 MPa or more, an elongation of 1% or more, and a fatigue limit of 200 MPa or more. The precursor is heat-treated at 650~750℃ for 4~6 hours, then treated at 1100~1300℃ for 0.5~1 hours, and then mixed with molten aluminum alloy.

4. The method of making ultra-high-strength, fatigue-resistant ceramic particulate aluminum matrix composite material of claim 1, wherein, After melting aluminum, it is poured into a mold. The precursor is placed in the mold containing the aluminum melt, so that the aluminum melt completely covers the blank. After cooling, an intermediate is obtained. The intermediate is placed in molten aluminum alloy to obtain an ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

5. The method of making ultra-high-strength, fatigue-resistant ceramic particulate aluminum matrix composite material of claim 1, wherein, Includes the following steps: a. Preparation of magnesium hydroxide whiskers; Take titanium and magnesium hydroxide whiskers, add alcohol and grind and mix at a speed of 50~100 rpm for 10~30 min to obtain a mixture; b. Under an argon atmosphere, aluminum powder and boron powder are first ground and dispersed, and then the mixture is added and ground and dispersed to obtain a mixed powder; the mixed powder is pressed into blocks with a relative density of 50-70% to obtain a blank; c. Heat-treat the blank at 350~450℃ for 2~4h to soften the blank and generate pores to obtain a precursor; add the precursor to molten aluminum alloy to obtain an ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material.

6. The method of claim 5, wherein the ceramic particle reinforced aluminum matrix composite material has a tensile strength of 400 MPa or more, an elongation of 1% or more, and a fatigue limit of 200 MPa or more. In step b, aluminum powder and boron powder are ground at 250-350 rpm for 2-3 hours under an argon atmosphere. Then, the mixture is added and ground at 100-200 rpm for 0.5-1.5 hours to obtain a mixed powder.

7. The method of making ultra-high-strength, fatigue-resistant ceramic particulate aluminum matrix composite material of claim 1, wherein, The preparation of the magnesium hydroxide whiskers includes the following steps: Prepare a sodium carbonate and magnesium sulfate solution. While stirring, add sodium carbonate dropwise to the magnesium sulfate solution and react at 30-50℃ for 0.5-3 hours. Separate and collect the precipitate, wash thoroughly with water to obtain magnesium carbonate whiskers. Disperse the obtained magnesium carbonate whiskers in water and react at 50-65℃ until the solvent evaporates to dryness to obtain magnesium hydroxide whiskers.

8. The method of claim 7, wherein the ceramic particulate is present in an amount of 0.1 to 10 vol%. The mass ratio of magnesium sulfate to sodium carbonate is 1:1~2.5; magnesium carbonate and ammonium sulfate are ground and mixed, and then calcined at 480~580℃ for 0.5~2h to obtain magnesium sulfate.

9. The method of claim 8, wherein the ceramic particulate is present in an amount of 0.1 to 10 vol%. The mass ratio of magnesium carbonate to ammonium sulfate is 1:2.5~3.

10. An ultra-high strength fatigue-resistant ceramic particle aluminum matrix composite material prepared by the method of any one of claims 1 to 9.

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