Az91d-based damping composite material and preparation method and application thereof

Abstract

The application discloses an AZ91D-based damping composite material and a preparation method and application thereof, and belongs to the technical field of composite materials and preparation thereof.The preparation method is as follows: taking AZ91D magnesium alloy as a matrix material, performing partial self-oxidation in a molten state; and then stirring uniformly under a protective atmosphere to obtain the AZ91D-based damping composite material through casting.Compared with the original AZ91D magnesium alloy, the damping performance of the AZ91D-based damping composite material prepared by the application is greatly improved, the AZ91D-based damping composite material also has excellent yield strength and good corrosion resistance, and is suitable for preparing automobile parts.The preparation process of the AZ91D-based composite material is simple and easy to operate, has low requirement on equipment, and is safe and free of danger in the production process.

Description

Technical Field

[0001] This invention belongs to the field of composite materials and their preparation technology, and particularly relates to an AZ91D-based damping composite material, its preparation method and application. Background Technology

[0002] Magnesium alloys, as a widely used engineering material, possess excellent properties such as good damping performance, low density, and high specific strength. These properties make magnesium alloys widely used in aerospace, automotive manufacturing, rail transportation, and other fields. However, with the rapid development of industrialization, industrial production has placed higher demands on the various properties of magnesium alloys. The prominent vibration and noise problems in the aerospace field make improving the damping performance of magnesium alloys urgent; the corrosion problems of the bottom plates in ships due to water and oxygen make improving the corrosion resistance of magnesium alloys particularly important; and in the automotive manufacturing field, maintaining high damping performance while improving the strength of magnesium alloys has always been key to lightweighting automobiles. Using magnesium alloys as the matrix material to prepare composite materials, thereby improving the corrosion resistance, damping performance, and yield strength of magnesium-based composite materials, will generate significant social and economic benefits.

[0003] Therefore, how to improve the corrosion resistance, damping properties and yield strength of magnesium-based composite materials is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes an AZ91D-based damping composite material, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing AZ91D-based damping composite material, the method being as follows: using AZ91D magnesium alloy as the matrix material, performing partial self-oxidation in the molten state; then stirring evenly under a protective atmosphere, and casting to obtain the final product.

[0007] Preferably, the matrix material is heated to a molten state at a temperature of 700–720°C for 10–15 minutes.

[0008] Preferably, a flame retardant layer needs to be applied to the surface of the base material before heating.

[0009] The flame retardant is a mixture of magnesium chloride and barium chloride in a mass ratio of 1:1.

[0010] Preferably, the self-oxidation is carried out in an air atmosphere.

[0011] The self-oxidation temperature is 680–700℃, and the time is 2–10 min.

[0012] The temperature for heat preservation is the same as the temperature for self-oxidation, and the heat preservation time is 10 minutes.

[0013] Beneficial effects: The time and temperature of self-oxidation are key factors in determining the degree of self-oxidation. By controlling the temperature of self-oxidation to 680-700℃ and the time to 2-10 minutes, the degree of self-oxidation of magnesium alloys can be ensured to reach the best effect.

[0014] Preferably, the stirring time is 1 to 5 minutes and the stirring speed is 500 to 900 rpm.

[0015] Beneficial effects: The stirring rate and time affect the metallographic structure of magnesium alloys. The grain size becomes smaller with the increase of stirring time and stirring intensity, and the degree of microstructure refinement increases. The size of oxide particles also becomes smaller with the increase of stirring intensity. The present invention controls the stirring time to 1 to 5 minutes and the stirring rate to 500 to 900 rpm, which can achieve the best effect of grain refinement of the alloy.

[0016] Preferably, the matrix material is preheated twice before melting.

[0017] The two preheating processes are as follows: the reaction vessel is preheated once by coating the inner and outer surfaces of the reaction vessel with a water glass solution, maintaining the temperature of the first preheating until the water glass solution evaporates, and then a second preheating is performed.

[0018] Preferably, the temperature of the first preheating is 400-450°C, and the temperature of the second preheating is 660-700°C.

[0019] Beneficial effect: The surface of the reaction vessel contains a large amount of water vapor. The purpose of preheating is to remove the water vapor completely to prevent it from entering the melt.

[0020] Preferably, the slag is removed under a protective atmosphere before self-oxidation.

[0021] Another object of the present invention is to provide an AZ91D-based damping composite material prepared by a method for preparing AZ91D-based damping composite material.

[0022] Another objective of this invention is to provide an application of AZ91D-based damping composite material in the manufacture of automotive parts.

[0023] The present invention has the following advantages and technical effects:

[0024] This invention uses AZ91D magnesium alloy as the matrix material, and performs partial self-oxidation in the molten state to introduce some metal oxides into the alloy composition, forming a metal / metal oxide damping composite material. By controlling the self-oxidation time and temperature, the degree of oxidation is controlled, and the stirring process is combined to achieve the effect of refining the grains, thereby achieving the effects of damping performance, improving corrosion resistance and yield strength.

[0025] The composite material prepared in this invention mainly consists of α-Mg, MgO, and Mg 17 Al 12 Composed of (β phase) and a small amount of Al2O3, the AZ91D-based damping composite material prepared by this invention has significantly improved damping performance compared with the original AZ91D magnesium alloy. It also has excellent yield strength and good corrosion resistance, making it suitable for manufacturing automotive parts.

[0026] Compared with the prior art, the preparation process of the AZ91D-based composite material of the present invention is simple and easy to operate, has low equipment requirements, and is safe and hazardless in the production process. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0028] Figure 1 Microstructure diagrams of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5;

[0029] in, Figure 1 (a) is a microstructure diagram of the matrix material AZ91D;

[0030] Figure 1 (b) is a microstructure diagram of the composite material AZ91D-1;

[0031] Figure 1 Image (c) shows the microstructure of the composite material AZ91D-3;

[0032] Figure 1 The middle (d) image shows the microstructure of the composite material AZ91D-5.

[0033] Figure 2 The results of EDS analysis of the composite material AZ91D-3;

[0034] in, Figure 2 In the middle (a), the energy dispersive spectroscopy (EDS) results of the composite material AZ91D-3 are shown. The three points are the positions of the β phase, matrix material, and oxide selected for the EDS analysis, respectively.

[0035] Figure 2 (b) shows the energy dispersive spectroscopy (EDS) analysis results of the composite material AZ91D-3, which reveals the distribution of each element.

[0036] Figure 3 The figures show the XRD analysis results of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5.

[0037] Figure 4 The strain amplitude-damping curves are for matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5.

[0038] Figure 5 The values ​​represent the damping values ​​of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5 under the same strain amplitude.

[0039] Figure 6 The polarization curves are for the matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5. Detailed Implementation

[0040] This invention provides a method for preparing AZ91D-based damping composite material, the method being as follows: using AZ91D magnesium alloy as the matrix material, performing partial self-oxidation in the molten state; then stirring uniformly under a protective atmosphere, and casting to obtain the final product;

[0041] The protective atmosphere is preferably a nitrogen atmosphere or an argon atmosphere.

[0042] In some embodiments of the present invention, the matrix material is molten under heating conditions. The heating temperature is preferably 700-720°C, more preferably 720°C in the embodiments; the heating time is preferably 10-15 min, more preferably 15 min in the embodiments.

[0043] In some embodiments of the present invention, a flame retardant is applied to the surface of the base material before heating to prevent combustion or excessive oxidation.

[0044] In some embodiments of the present invention, the flame retardant is a mixture of magnesium chloride and barium chloride in a mass ratio of 1:1.

[0045] In some embodiments of the present invention, the self-oxidation is preferably carried out in an air atmosphere.

[0046] In some embodiments of the present invention, the temperature of the self-oxidation is preferably 680-700°C, more preferably 700°C in the embodiments; the time is preferably 2-10 min, more preferably 2 min in the embodiments.

[0047] The temperature of the heat preservation is preferably the same as the temperature of self-oxidation. In some embodiments of the present invention, the heat preservation time is preferably 10 minutes.

[0048] In some embodiments of the present invention, the stirring time is preferably 3 to 5 minutes, more preferably 3 minutes in the embodiments; the stirring speed is preferably 500 to 900 rpm, more preferably 700 rpm in the embodiments.

[0049] In some embodiments of the present invention, it is preferable to preheat the base material twice before melting it.

[0050] The two preheating processes are as follows: the reaction vessel is preheated once by coating the inner and outer surfaces of the reaction vessel with a water glass solution, maintaining the temperature of the first preheating until the water glass solution evaporates, and then a second preheating is performed.

[0051] The modulus of the water glass is preferably 1.5 to 2.0.

[0052] In a preferred embodiment of the present invention, the temperature of the first preheating is preferably 400-450°C, more preferably 450°C in the embodiment; the temperature of the second preheating is preferably 660-700°C, more preferably 680°C in the embodiment.

[0053] In some embodiments of the present invention, it is preferable to remove the slag under a protective atmosphere before self-oxidation.

[0054] The protective atmosphere is preferably a nitrogen atmosphere or an argon atmosphere.

[0055] The present invention also provides an AZ91D-based damping composite material prepared by a method for preparing AZ91D-based damping composite material.

[0056] This invention also provides an application of AZ91D-based damping composite material in the manufacture of automotive parts.

[0057] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0058] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0059] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0060] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0061] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0062] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0063] All raw materials used in the following embodiments of the present invention are commercially available.

[0064] The following embodiments are further illustrations of the technical solution of the present invention.

[0065] Example 1

[0066] (1) Material preparation: AZ91D magnesium alloy ingot, flame retardant (magnesium chloride and barium chloride in a mass ratio of 1:1), water glass solution (modulus of 1.8).

[0067] (2) Equipment preparation: XMT type pit resistance furnace smelting equipment, stainless steel smelting crucible, mechanical stirring paddle.

[0068] (3) Melting: Preheat the crucible to 450°C, remove the crucible and coat the inner and outer surfaces with water glass solution, continue to heat it in the furnace until the water glass evaporates, preheat the crucible to 680°C again, remove the crucible and place the AZ91D magnesium alloy ingot at the bottom, sprinkle a layer of flame retardant, and then place the crucible in the furnace cavity to continue heating; when the temperature reaches the set oxidation temperature of 700°C, hold it for 15 minutes to obtain a molten melt; then open the furnace lid and remove the slag on the surface of the molten metal under a nitrogen atmosphere; cut off the protective gas and let the melt come into contact with air, oxidize at 700°C for 2 minutes; introduce protective nitrogen again and turn on the mechanical stirrer to stir the melt, the stirring time is set to 3 minutes and the stirring speed is set to 700 rpm.

[0069] (4) Casting: After holding the temperature for 10 minutes, open the furnace cover, remove the residue, and pour the molten metal into the steel mold for casting and molding to obtain the AZ91D-based damping composite material, which is denoted as AZ91D-3.

[0070] Example 2

[0071] (1) Material preparation: AZ91D magnesium alloy ingot, flame retardant (magnesium chloride and barium chloride in a mass ratio of 1:1), water glass solution (modulus of 1.8).

[0072] (2) Equipment preparation: XMT type pit resistance furnace smelting equipment, stainless steel smelting crucible, mechanical stirring paddle.

[0073] (3) Melting: Preheat the crucible to 450°C, remove the crucible and coat the inner and outer surfaces with water glass solution, then put it back into the furnace and heat until the water glass evaporates. Preheat the crucible to 680°C again, remove the crucible and place the AZ91D magnesium alloy ingot at the bottom, sprinkle a layer of flame retardant, and then place the crucible in the furnace cavity to continue heating. When the temperature reaches the set oxidation temperature of 700°C, hold it for 15 minutes to obtain a molten melt. Then open the furnace lid and remove the slag on the surface of the molten metal under a nitrogen atmosphere. Cut off the protective gas and let the melt come into contact with the air. Oxidize at 700°C for 2 minutes. Then introduce protective nitrogen again and turn on the mechanical stirrer to stir the melt. The stirring time is set to 5 minutes and the stirring speed is set to 900 rpm.

[0074] (4) Casting: After holding the temperature for 10 minutes, open the furnace cover, remove the residue, and pour the molten metal into the steel mold for casting and molding. The AZ91D-based damping composite material can be obtained and is denoted as AZ91D-5.

[0075] Comparative Example 1

[0076] (1) Material preparation: AZ91D magnesium alloy ingot, flame retardant (magnesium chloride and barium chloride in a mass ratio of 1:1), water glass solution (modulus of 1.8).

[0077] (2) Equipment preparation: XMT type pit resistance furnace smelting equipment, stainless steel smelting crucible, mechanical stirring paddle.

[0078] (3) Melting: Preheat the crucible to 450°C, remove the crucible and coat the inner and outer surfaces with water glass solution, continue to heat it in the furnace until the water glass evaporates, preheat the crucible to 680°C again, remove the crucible and place the AZ91D magnesium alloy ingot at the bottom, sprinkle a layer of flame retardant, and then place the crucible in the furnace cavity to continue heating; when the temperature reaches the set oxidation temperature of 700°C, hold it for 15 minutes to obtain a molten melt; then open the furnace lid and remove the slag on the surface of the molten metal under a nitrogen atmosphere; cut off the protective gas and let the melt come into contact with the air, oxidize at 700°C for 2 minutes; introduce protective nitrogen again and turn on the mechanical stirrer to stir the melt, the stirring time is set to 1 minute and the stirring speed is set to 500 rpm.

[0079] (4) Casting: After holding the temperature for 10 minutes, open the furnace cover, remove the residue, and pour the molten metal into the steel mold for casting to obtain the AZ91D-based damping composite material, which is denoted as AZ91D-1.

[0080] Sample characterization

[0081] (1) Microscopic morphology and phase analysis: Figure 1 Microstructure diagrams of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5.

[0082] Microstructural analysis of the samples revealed that AZ91D-1 exhibited grain sizes on the micrometer scale, indicating fine grains. Intense mechanical stirring broke down the dendritic network skeleton, refining the microstructure. At this stage, the oxide particle content within the composite material was approximately 1.3%. AZ91D-3 showed even finer grain sizes with increasing stirring time and intensity, resulting in increased microstructural refinement. The oxide particle size also decreased with increasing stirring intensity, leading to an increase in oxide content to approximately 1.7%. The composite material also exhibited micrometer-scale grain sizes, with fine grains. Intense mechanical stirring broke down the dendritic network skeleton, refining the microstructure. The oxide particle size further decreased with increasing stirring intensity, resulting in another increase in oxide content to approximately 2.0%. Table 1 shows the oxide contents of composite materials AZ91D-1, AZ91D-3, and AZ91D-5, obtained using software analysis.

[0083] Table 1. Oxide content of composite materials AZ91D-1, AZ91D-3, and AZ91D-5

[0084]

[0085] Figure 2 The results of EDS analysis of the composite material AZ91D-3 are shown; among them, Figure 2 In the middle (a), the results of energy dispersive spectroscopy (EDS) analysis of the composite material AZ91D-3 are shown. The three points represent the positions of the β phase, oxide, and matrix material selected for EDS analysis, respectively. Figure 2 Table (b) shows the energy dispersive spectroscopy (EDS) analysis results of the composite material AZ91D-3, revealing the distribution of each element. Table 2 presents the EDS fitting data for the composite material AZ91D-3 prepared in this invention. The results show that the main constituent elements of the β phase are Mg and Al, with a small amount of O and trace amounts of C and Zn; the main constituent elements of the matrix material are Mg and Al, with a small amount of O and trace amounts of C and Zn; the main constituent elements of the oxide are Mg and O, with the Al content significantly lower than that of the matrix material but slightly higher, and the O content significantly higher, also containing trace amounts of C and Zn.

[0086] Table 2. Energy dispersive spectroscopy (EDS) data of composite material AZ91D-3

[0087]

[0088] (2) XRD analysis: Figure 3 The images show the XRD analysis results of the matrix material AZ91D, composite materials AZ91D-1, AZ91D-3, and AZ91D-5. XRD analysis of the samples further determined the phase composition of the composite materials. According to the XRD diffraction peaks, AZ91D-1, AZ91D-3, and AZ91D-5 are mainly composed of α-Mg, MgO, and MgO. 17 Al 12 It consists of (β phase) and a small amount of Al2O3.

[0089] (3) Damping performance test: The matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3 and composite material AZ91D-5 were respectively made into standard specimens of 50×5×1mm, and the damping performance of the specimens was tested on the dynamic thermomechanical analyzer (DMA-Q800). Figure 4 The strain amplitude-damping curves are for matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5. Figure 5 The values ​​represent the damping values ​​of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5 under the same strain amplitude.

[0090] As shown above, compared with the matrix material AZ91D magnesium alloy, the damping value of the composite material AZ91D-1 is significantly higher than that of the matrix alloy. In the low strain amplitude stage, the increase in damping value of AZ91D-1 with increasing strain amplitude is not significant, while in the high strain amplitude stage, the damping performance of AZ91D-1 is significantly improved. Similarly, the damping value of AZ91D-3 is also significantly higher than that of the matrix alloy. In the low strain amplitude stage, the increase in damping value of AZ91D-3 with increasing strain amplitude is not significant, while in the high strain amplitude stage, the damping performance of AZ91D-3 is significantly improved. However, compared to AZ91D-1, the damping performance of AZ91D-3 decreased with increasing stirring speed. This is mainly attributed to the smaller oxide particle size, which significantly increased the number of dislocation pinning points, adversely affecting dislocation damping. Compared to the matrix material, AZ91D-5 showed a significant improvement in damping value. In the low strain amplitude stage, the increase in damping value of AZ91D-5 was not significant with increasing strain amplitude, while in the high strain amplitude stage, the damping performance of AZ91D-5 was significantly improved. Compared to AZ91D-1 and AZ91D-3, with increasing stirring speed, the size of oxide particles and β phase in the composite material further decreased, resulting in more uniform dispersion. Small particles were difficult to break down, further reducing the damping improvement ability of AZ91D-5. The increase in the number of dislocation points had a greater adverse effect on the damping performance of AZ91D-5, leading to a further decline in its damping performance.

[0091] (4) Yield strength test: The tensile strength of the materials was tested using an AG-X series universal electronic tensile testing machine, with the tensile speed set to 1 mm / min. Table 3 shows the yield strength of the matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3 and composite material AZ91D-5.

[0092] Table 3. Yield strength of matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3 and composite material AZ91D-5

[0093]

[0094] As shown above, the yield strength of composite materials AZ91D-1, AZ91D-3, and AZ91D-5 is significantly higher than that of the matrix material. The high yield strength of composite materials AZ91D-3 and AZ91D-5 is due to the following: as the stirring speed increases, the size of the oxide particles decreases, their distribution becomes more uniform, the volume fraction increases, the thermal mismatch area decreases, and stress concentration is alleviated. This results in higher yield strengths for AZ91D-3 and AZ91D-5, exceeding those of the matrix material and AZ91D-1, reaching 84.49 MPa and 92.99 MPa respectively.

[0095] (5) Corrosion resistance test: The corrosion resistance of AZ91D as the matrix material, AZ91D-1, AZ91D-3 and AZ91D-5 as composite materials were tested on the CHI660A electrochemical workstation. Figure 6 The polarization curves are shown in Table 4 for the matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5. The electrochemical fitting data for the matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5 are also shown in Table 4.

[0096] Table 4. Electrochemical fitting data for matrix material AZ91D, composite material AZ91D-1, composite material AZ91D-3, and composite material AZ91D-5.

[0097]

[0098]

[0099] As can be seen from the above, compared with the matrix material AZ91D, the introduction of oxide particles during the preparation of AZ91D-1 causes the corrosion potential to shift negatively, decreasing to -1.481V, while the corrosion current density increases slightly, reaching 0.0699 mA / cm². 2 At this point, the large oxide particles within AZ91D-1 easily create voids and cracks with the surrounding matrix, inducing pitting corrosion and ultimately leading to a decrease in corrosion resistance. With increasing stirring speed, the potential of AZ91D-3 shifts positively to -1.424V, and the corrosion current density decreases significantly to 0.0094 mA / cm². 2The corrosion resistance was significantly improved. With further increases in stirring speed, the reduction in the size of oxide particles and the β phase in AZ91D-5 effectively weakened the tendency for galvanic corrosion in the material, which was beneficial for blocking charge transfer between the corrosive medium and the magnesium matrix. Furthermore, the protective layer composed of the β phase became more dense, causing the potential of AZ91D-5 to rise to -1.404V and the corrosion current density to decrease to 0.0054mA / cm². 2 The corrosion resistance of AZ91D-5 has been further improved.

[0100] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An AZ91D-based damping composite material, characterized in that, The preparation method is as follows: using AZ91D magnesium alloy as the base material, a layer of flame retardant is sprinkled on the surface of the base material, and the base material is molten under heating conditions, and partial self-oxidation is carried out in the molten state; then, it is stirred evenly under a protective atmosphere and cast to obtain the product. The self-oxidation is carried out in an air atmosphere; the temperature of the self-oxidation is 680-700℃, and the time is 2-10 min. The flame retardant is a mixture of magnesium chloride and barium chloride in a mass ratio of 1:1; The stirring time is 3 to 5 minutes, and the speed is 700 to 900 rpm; The AZ91D-based damping composite material mainly consists of α-Mg, MgO, and β-phase Mg. 17 Al 12 It is composed of a small amount of Al2O3.

2. The AZ91D-based damping composite material according to claim 1, characterized in that, The heating temperature is 700-720℃, and the time is 10-15 minutes.

3. The AZ91D-based damping composite material according to claim 1, characterized in that, Before melting the base material, the crucible is preheated twice. The two preheating processes are as follows: the crucible is preheated once by coating the inner and outer surfaces of the crucible with water glass solution, maintaining the temperature of the first preheating until the water glass solution evaporates, and then the crucible is preheated a second time.

4. The AZ91D-based damping composite material according to claim 3, characterized in that, The temperature for the first preheating is 400–450°C, and the temperature for the second preheating is 660–700°C.

5. The AZ91D-based damping composite material according to any one of claims 1-4, characterized in that, Remove the slag under a protective atmosphere before self-oxidation.

6. The application of the AZ91D-based damping composite material according to any one of claims 1-5 in the manufacture of automotive parts.

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