Metal-ceramic gradient material and preparation method thereof

Abstract

The invention belongs to the field of gradient materials, and particularly relates to a metal-ceramic gradient material and a preparation method thereof.The method comprises the steps that S1, metal powder and ceramic powder are selected, and the metal powder is modified; s2, ceramic powder and modified metal powder are mixed and laid in a mold according to a set gradient; s3, carrying out pressure generation on the mixed powder to obtain a semi-compact green body; s4, performing low-temperature pre-sintering on the green body to obtain a metal-ceramic biscuit; and S5, performing high-temperature sintering on the metal-ceramic biscuit to obtain the metal-ceramic gradient material. The method is simple in process, short in production period and high in production efficiency. Compared with an existing gradient material prepared through powder metallurgy, the advantages of metal and ceramic materials are absorbed, the metal-rich part shows higher strength than pure metal, and the ceramic-rich part shows certain toughness. The prepared metal-ceramic gradient material is a continuous component gradient material, gradient layers are well combined, and the problem that thermodynamic properties of different materials are not matched is solved to a certain extent.

Description

Technical Field

[0001] The invention belongs to the technical field of gradient materials, and in particular relates to a metal-ceramic gradient material and a preparation method thereof. Background Art

[0002] Functionally graded materials refer to heterogeneous materials with a spatially gradient distribution of composition or structure. Due to the gradient of composition or structure, the properties and functions of the material also change in a gradient. Gradient materials have important application value in the fields of biomedicine, electronic information, aerospace, and atomic energy.

[0003] Metal-ceramic gradient materials absorb the advantages of both metal and ceramic materials. The materials have good properties such as fracture resistance, thermal shock resistance, heat insulation, and internal thermal stress relief in ultra-high temperature environments.

[0004] Preparation science and technology are the basis for the application and development of functional gradient materials. At present, the preparation methods of metal / ceramic functional gradient materials mainly include self-propagating high-temperature combustion synthesis, plasma spraying, vapor deposition, powder metallurgy, etc. Among them, powder metallurgy is considered to be one of the more flexible and promising methods for preparing large components. However, the current powder metallurgy method mainly adopts the lamination method, that is, the two powders are first mixed in different proportions according to the design, and then pressed and sintered layer by layer. The gradient change direction of the gradient material is along the longitudinal direction of the pressure head pressure.

[0005] In the prior art, for example, the invention patent CN115029598A discloses "a ZrB2-Mo gradient material and preparation method", which prepares a ZrB2-Mo gradient material by a lamination method. Compared with the homogeneous ZrB2 / Mo composite material, the ZrB2-Mo gradient material prepared by the invention effectively alleviates the thermal stress caused by the difference in thermal expansion coefficient between the ceramic material and the metal material, and greatly improves the thermal shock ablation resistance.

[0006] However, this method has great limitations. The gradient material obtained by the lamination method is composed of multiple layers of components with different contents. It is a step-shaped gradient material, which has certain difficulties in controlling the lamination size. At the same time, the gradient material will have a step-change in composition at the lamination interface, resulting in problems such as mismatch in the thermodynamic properties of the interlayer bonding parts, causing the material to be delaminated and damaged, affecting the performance of the material itself. Summary of the invention

[0007] In view of the problems in the existing lamination method for preparing gradient materials, such as difficulty in controlling the lamination size and step-change in composition at the lamination interface, the present invention provides a metal-ceramic gradient material and a preparation method thereof. A powder storage bin with a combined structure is used to complete gradient mixing of metal / ceramic two-component powders during the powder spreading process to prepare a metal-ceramic gradient material with continuously distributed components.

[0008] The present invention provides a method for preparing a metal-ceramic gradient material, comprising the following steps:

[0009] S1. Selecting metal powder and ceramic powder, and modifying the metal powder;

[0010] S2, mixing the ceramic powder and the modified metal powder and laying them in a mold according to a set gradient;

[0011] S3, pressing the mixed powder in the mold to obtain a semi-dense green compact;

[0012] S4, pre-sintering the green body obtained in step S3 at a low temperature to obtain a metal-ceramic green body;

[0013] S5, sintering the metal-ceramic green body obtained in step S4 at high temperature to obtain a metal-ceramic gradient material.

[0014] Any possible implementation as described above further provides an implementation, in step S1, the metal powder and the ceramic powder are both spherical powders, the particle sizes of the metal powder and the ceramic powder are 15 to 53 μm, and the sintering temperature of the metal powder is higher than that of the ceramic powder.

[0015] According to any possible implementation described above, there is further provided an implementation, in step S1, a binder is added to modify the metal powder, the binder is stearic acid powder, the particle size of the binder is 1-5 μm, and the mass fraction of the binder is 5-10 wt.% of the metal powder.

[0016] Any possible implementation as described above further provides an implementation, in step S1, the metal powder and the binder are mixed according to mass percentage using a V-type mixer to prepare a modified metal powder, the rotation speed of the V-type mixer is 60 to 80 rpm, and the total rotation time is 24 to 48 hours.

[0017] Any possible implementation as described above further provides an implementation, in which in step S1, the fluidity of the modified metal powder is 20 to 45 s / 100 g.

[0018] Any possible implementation as described above further provides an implementation method, in which in step S2, the modified metal powder and the ceramic powder are respectively placed in corresponding partitions of the powder storage bin, and the partitions are V-shaped partitions; the scraper plate moves on the powder storage bin to scrape the powder, and the mixed powder with a gradient ratio is pushed into the mold to achieve the laying of the gradient powder.

[0019] As any possible implementation described above, a further implementation is provided, in step S3, the raw pressure head pressure is 10 to 20 MPa, and the duration is 60 to 120 seconds.

[0020] Any possible implementation as described above, further provides an implementation, in step S4, the heating rate of the low-temperature pre-sintering is 0.1-0.5°C / min, the low-temperature sintering temperature is 500-600°C, the sintering atmosphere is a protective gas, and the low-temperature sintering time is 60-120 minutes.

[0021] Any possible implementation as described above, further provides an implementation, in step S5, the heating rate of the high temperature sintering is 5-10°C / min, the sintering temperature is lower than the melting point of the metal powder and higher than the ceramic sintering temperature, the sintering atmosphere is a protective gas, and the sintering time is 60-120 minutes.

[0022] On the other hand, the present invention also provides a metal-ceramic gradient material, which is prepared by the above method.

[0023] Any possible implementation as described above further provides an implementation, wherein one end of the metal-ceramic gradient material is a ceramic-rich end and the other end is a metal-rich end (the ceramic-rich and metal-rich ends can be 50-100%), and between the two ends is a metal-ceramic composite material with a continuous gradient change.

[0024] The beneficial effects of the present invention are:

[0025] Based on powder metallurgy technology, the process is simple, the production cycle is short, and the production efficiency is high. Compared with the existing powder metallurgy method for preparing gradient materials, the present invention changes the gradient change direction of the gradient material prepared by the previous lamination method from the longitudinal pressure direction of the pressure head to the horizontal direction perpendicular to the pressure direction, and processes the gradient material with continuous gradient change through the powder storage-powder spreading process. At the same time, the prepared metal-ceramic gradient material absorbs the advantages of both metal / ceramic materials. The metal-rich part shows higher strength than pure metal, and the ceramic-rich part shows a certain toughness. In addition, the prepared metal-ceramic gradient is a continuous composition gradient material with good bonding between gradient layers, which solves the problem of mismatch in thermodynamic properties between different materials to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a schematic flow chart of a method for preparing a metal-ceramic gradient material of the present invention;

[0027] Figure 2 Shown is the green body of the ZrO2-316L gradient material prepared in Example 1 of the present invention (the left end is the ceramic-rich end, and the right end is the metal-rich end). DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be described in detail below in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0029] like Figure 1 As shown, the present invention provides a method for preparing a metal-ceramic gradient material, comprising the following steps:

[0030] S1. Selecting metal powder and ceramic powder, and modifying the metal powder;

[0031] S2, mixing the ceramic powder and the modified metal powder and laying them in a mold according to a set gradient;

[0032] S3, pressing the mixed powder in the mold to obtain a semi-dense green compact;

[0033] S4, pre-sintering the green body obtained in step S3 at a low temperature to obtain a metal-ceramic green body;

[0034] S5, sintering the metal-ceramic green body obtained in step S4 at high temperature to obtain a metal-ceramic gradient material.

[0035] Any possible implementation as described above further provides an implementation, in step S1, the metal powder and the ceramic powder are both spherical powders, the particle sizes of the metal powder and the ceramic powder are 15 to 53 μm, and the sintering temperature of the metal powder is higher than that of the ceramic powder.

[0036] Any possible implementation as described above further provides an implementation, in step S1, a binder is added to modify the metal powder, the binder is stearic acid powder, the particle size of the binder is 1 to 5 μm, and the mass fraction of the binder is 5 to 10 wt.% of the metal powder.

[0037] Any possible implementation as described above further provides an implementation, in step S1, the metal powder and the binder are mixed according to mass percentage using a V-type mixer to prepare a modified metal powder, the rotation speed of the V-type mixer is 60 to 80 rpm, and the total rotation time is 24 to 48 hours.

[0038] Any possible implementation as described above further provides an implementation, in which in step S1, the fluidity of the modified metal powder is 20 to 45 s / 100 g.

[0039] Any possible implementation as described above further provides an implementation method, in which in step S2, the modified metal powder and the ceramic powder are respectively placed in corresponding partitions of the powder storage bin, and the partitions are V-shaped partitions; the scraper plate moves on the powder storage bin to scrape the powder, and the mixed powder with a gradient ratio is pushed into the mold to achieve the laying of the gradient powder.

[0040] As any possible implementation described above, a further implementation is provided, in step S3, the raw pressure head pressure is 10 to 20 MPa, and the duration is 60 to 120 seconds.

[0041] Any possible implementation as described above, further provides an implementation, in step S4, the heating rate of the low-temperature pre-sintering is 0.1-0.5°C / min, the low-temperature sintering temperature is 500-600°C, the sintering atmosphere is a protective gas, and the low-temperature sintering time is 60-120 minutes.

[0042] Any possible implementation as described above, further provides an implementation, in step S5, the heating rate of the high temperature sintering is 5-10°C / min, the sintering temperature is lower than the melting point of the metal powder and higher than the ceramic sintering temperature, the sintering atmosphere is a protective gas, and the sintering time is 60-120 minutes.

[0043] On the other hand, the present invention also provides a metal-ceramic gradient material, which is prepared by the above method.

[0044] Any possible implementation as described above further provides an implementation, wherein one end of the metal-ceramic gradient material is a ceramic-rich end and the other end is a metal-rich end (the ceramic-rich and metal-rich ends can be 50-100%), and between the two ends is a metal-ceramic composite material with a continuous gradient change.

[0045] Example 1

[0046] This embodiment provides a method for preparing a ZrO2-316L gradient material, wherein the two ends are ZrO2-rich ceramic and 316L-rich metal layers (the content of the ZrO2-rich ceramic and 316L-rich metal layers can be 50-100%), and the middle is a ZrO2-316L composite material layer with a continuous gradient component change. The method includes the following specific steps:

[0047] Step 1: Select 316L and stearic acid as raw materials, and modify the 316L metal powder. Use a V-type mixer to prepare a mixed powder of 316L / stearic acid according to mass percentage. The mass fraction of stearic acid is 5wt.%. The rotation speed of the V-type mixer is 60rpm, and the total rotation time is 48 hours.

[0048] Step 2: Select ZrO2 and modified 316L powder as raw materials, place the ZrO2 and 316L powders in the corresponding partitions of the powder storage bin, and remove the powder storage bin after the powder is filled.

[0049] As the scraper moves, it pushes the powder mixed with gradient ratio into the mold to achieve the laying of gradient material powder; the thickness of each layer of powder is 0.1-0.2mm, and the number of times of laying powder is 50 times;

[0050] Step 3: After the gradient powder is laid in the mold, it is pressed with a pressing head pressure of 20 MPa and a duration of 90 seconds to obtain a semi-densified green body.

[0051] Step 4: Place the green body into a sintering furnace for pre-sintering in an argon atmosphere; the heating rate is 0.5°C / min, the sintering temperature is 600°C, the holding time is 120 minutes, and the ZrO2-316L green body is obtained after cooling to room temperature in the furnace.

[0052] Step 5: Place the green blank into a sintering furnace for sintering in an argon atmosphere; the heating rate is 10°C / min, the sintering temperature is 1300°C, the insulation time is 120 minutes, and the ZrO2-316L gradient material is obtained after cooling to room temperature in the furnace.

[0053] The materials prepared are as follows Figure 2 As shown, the left end is the ceramic-rich end and the right end is the metal-rich end. The ZrO2-rich ceramic end has a 10% compression elongation, and the 316L-rich metal end has a maximum yield strength of 324MPa. The ZrO2-316L gradient material has good interlayer bonding and excellent comprehensive performance.

[0054] Example 2

[0055] This embodiment provides a method for preparing an Al2O3-Ni gradient material, wherein the two ends are Al2O3-rich ceramic and Ni-rich metal layers (the content of the Al2O3-rich ceramic and Ni-rich metal layers can be 50-100%), and the middle is an Al2O3-Ni composite material layer with a continuous gradient component change. The method includes the following specific steps:

[0056] Step 1: Select Ni and stearic acid as raw materials to modify the single Ni metal powder. Use a V-type mixer to prepare a mixed powder of Ni / stearic acid according to mass percentage. The mass fraction of stearic acid is 5wt.%. The rotation speed of the V-type mixer is 60rpm, and the total rotation time is 48 hours.

[0057] Step 2: Select Al2O3 and modified Ni powder as raw materials, place the Al2O3 and Ni powders in the corresponding partitions of the powder storage bin, and remove the powder storage bin after the powder is filled.

[0058] As the scraper moves, it pushes the powder mixed with gradient ratio into the mold to achieve the laying of gradient material powder; the thickness of each layer of powder is 0.1-0.2mm, and the number of times of laying powder is 50 times;

[0059] Step 3: After the gradient powder is laid in the mold, it is pressed with a pressing head pressure of 20 MPa and a duration of 90 seconds to obtain a semi-densified green body.

[0060] Step 4: Place the green body into a sintering furnace for pre-sintering in an argon atmosphere; the heating rate is 0.1°C / min, the sintering temperature is 600°C, the holding time is 120 minutes, and the Al2O3-Ni green body is obtained after cooling to room temperature in the furnace.

[0061] Step 5: Place the green blank into a sintering furnace for sintering in an argon atmosphere; the heating rate is 10°C / min, the sintering temperature is 1400°C, the holding time is 60 minutes, and the Al2O3-Ni gradient material is obtained after cooling to room temperature. The Al2O3-rich ceramic end has a 5% compression elongation, and the Ni-rich metal end has a maximum yield strength of 275MPa.

[0062] Example 3

[0063] This embodiment provides a method for preparing an Al2O3-Cu gradient material, wherein the two ends are Al2O3-rich ceramic and Cu-rich metal layers (the Al2O3-rich ceramic layer may have a content of 50-60%, and the Cu-rich metal layer may have a content of 50-100%), and the middle is an Al2O3-Cu composite material layer with a continuous gradient composition change. The method comprises the following specific steps:

[0064] Step 1: Select Cu and stearic acid as raw materials to modify the single Ni metal powder. Use a V-type mixer to prepare a mixed powder of Cu / stearic acid according to mass percentage. The mass fraction of stearic acid is 5wt.%. The rotation speed of the V-type mixer is 60rpm, and the total rotation time is 48 hours.

[0065] Step 2: Select A12O3 and modified Cu powder as raw materials, place the A12O3 and Cu powders in the corresponding partitions of the powder storage bin, and remove the powder storage bin after the powders are filled.

[0066] As the powder scraper moves, it pushes the powder mixed with gradient ratio into the mold to achieve the laying of gradient material powder; the thickness of each layer of powder is 0.1-0.2mm, and the number of times of powder laying is 50 times;

[0067] Step 3: After the gradient powder is laid in the mold, it is pressed with a pressing head pressure of 20 MPa and a duration of 90 seconds to obtain a semi-densified green body.

[0068] Step 4: Place the green body into a sintering furnace for pre-sintering in an argon atmosphere; the heating rate is 0.1°C / min, the sintering temperature is 600°C, the holding time is 120 minutes, and the A12O3-Cu green body is obtained after cooling to room temperature in the furnace.

[0069] Step 5: Place the green blank into a sintering furnace for sintering in an argon atmosphere; the heating rate is 10°C / min, the sintering temperature is 1050°C, the holding time is 120 minutes, and the Al2O3-Cu gradient material is obtained after cooling to room temperature. The Al2O3-rich ceramic end has a compression elongation of 7%, and the yield strength of the Cu-rich metal end can reach up to 262MPa.

[0070] The present invention proposes a method for preparing metal-ceramic gradient materials by integrated preparation based on powder metallurgy technology, which has simple process, short production cycle and high production efficiency. Compared with the existing powder metallurgy preparation of gradient materials, the present invention changes the gradient change direction of the gradient material prepared by the previous lamination method from the longitudinal pressure direction of the pressure head to the horizontal direction perpendicular to the pressure direction, and processes the gradient material with continuous gradient change through the powder storage-powder spreading process. At the same time, the prepared metal-ceramic gradient material absorbs the advantages of both metal / ceramic materials, the metal-rich part shows higher strength than pure metal, and the ceramic-rich part shows a certain toughness. In addition, the prepared metal-ceramic gradient is a continuous composition gradient material, and the gradient layers are well bonded, which to a certain extent solves the problem of mismatch in thermodynamic properties between different materials.

[0071] Although several embodiments of the present invention have been given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A method for preparing a metal-ceramic gradient material, characterized in that: The method comprises the following steps: S1. Selecting metal powder and ceramic powder, and modifying the metal powder; S2, mixing the ceramic powder and the modified metal powder and laying them in a mold according to a set gradient; S3, pressing the mixed powder in the mold to obtain a semi-dense green compact; S4, pre-sintering the green body obtained in step S3 at low temperature to obtain a metal-ceramic green body; S5, sintering the metal-ceramic green body obtained in step S4 at high temperature to obtain a metal-ceramic gradient material.

2. The method for preparing a metal-ceramic gradient material according to claim 1, characterized in that: In step S1, the metal powder and the ceramic powder are both spherical powders, the particle sizes of the metal powder and the ceramic powder are 15-53 μm, and the sintering temperature of the metal powder is higher than that of the ceramic powder.

3. The method for preparing a metal-ceramic gradient material according to claim 1, characterized in that: In step S1, a binder is added to modify the metal powder, wherein the binder is stearic acid powder, the particle size of the binder is 1 to 5 μm, and the mass fraction of the binder is 5 to 10 wt.% of the metal powder.

4. The method for preparing a metal-ceramic gradient material according to claim 3, characterized in that: In step S1, the metal powder and the binder are mixed according to mass percentage using a V-type mixer to prepare a metal modified powder. The rotation speed of the V-type mixer is 60 to 80 rpm, and the total rotation time is 24 to 48 hours.

5. The method for preparing a metal-ceramic gradient material according to claim 4, characterized in that: In step S1, the fluidity of the modified metal powder is 20 to 45 s / 100 g.

6. The method for preparing a metal-ceramic gradient material according to claim 1, characterized in that: In step S2, the modified metal powder and the ceramic powder are respectively placed in corresponding partitions of the powder storage bin, and the partitions are V-shaped partitions; a powder scraper moves on the powder storage bin to scrape the powder, and the mixed powder with a gradient ratio is pushed into the mold to achieve the laying of the gradient powder.

7. The method for preparing a metal-ceramic gradient material according to claim 1, characterized in that: In step S3, the raw pressure head pressure is 10-20 MPa, and the duration is 60-120 seconds.

8. The method for preparing the metal-ceramic gradient material according to claim 1, characterized in that: In step S4, the heating rate of the low-temperature pre-sintering is 0.1-0.5°C / min, the low-temperature sintering temperature is 500-600°C, the sintering atmosphere is a protective gas, and the low-temperature sintering time is 60-120 minutes.

9. The method for preparing the metal-ceramic gradient material according to claim 1, characterized in that: In step S5, the heating rate of the high-temperature sintering is 5-10°C / min, the sintering temperature is lower than the melting point of the metal powder and higher than the ceramic sintering temperature, the sintering atmosphere is a protective gas, and the sintering time is 60-120 minutes.

10. A metal-ceramic gradient material, characterized in that: The metal-ceramic gradient material is prepared by the method according to any one of claims 1 to 9; One end of the metal-ceramic gradient material is a ceramic-rich end, and the other end is a metal-rich end. Between the two ends is a metal-ceramic composite material with a continuous gradient change. The ceramic volume of the ceramic-rich end accounts for 50-100%, and the metal volume of the metal-rich end accounts for 50-100%.

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