Ceramic preform, preparation method thereof and wear-resistant part

Abstract

The invention discloses a ceramic preform and a preparation method thereof and a wear-resistant part, and relates to the technical field of preparation methods of wear-resistant parts, and the preparation method comprises the following steps: dissolving ceramic powder in distilled water, carrying out acid pickling, neutralizing to be neutral by using ammonia water, carrying out solid-liquid separation, drying, and carrying out oxidizing roasting treatment to obtain rounded ceramic powder; mixing a solvent, a binder, a dispersing agent and a conditioning agent in proportion, magnetically stirring, and adding the rounded ceramic powder in batches for ball milling to obtain ceramic slurry; the ceramic slurry is injected into a freezing mold to be frozen, and a preform blank is obtained; performing freeze drying on the preform blank to form a blank of a three-dimensional network interpenetrating preform with honeycomb pores; and sintering the freeze-dried green body to obtain a ceramic preform, the ceramic preform has a three-dimensional network structure with honeycomb pores, does not deform during molten metal casting, can provide a good channel for infiltration of molten metal, and further enhances the performance of the composite material.

Description

Technical Field

[0001] The invention relates to the technical field of wear-resistant materials, and in particular to a ceramic preform and a preparation method thereof, and a wear-resistant part. Background Art

[0002] In industrial fields such as mining, metallurgy, electricity, and building materials, equipment is exposed to harsh working conditions of high wear and strong impact for a long time. Wear resistance has become a key factor affecting equipment life and production efficiency. Currently, the commonly used metal and ceramic materials each have their own performance shortcomings. Metal materials have good toughness and processing properties, but poor hardness and wear resistance. They are very easy to fail in severe wear environments, resulting in frequent replacement of equipment components, increased maintenance costs, and production stagnation. Although ceramic materials have high hardness, wear resistance, and strong chemical stability, they are brittle and easily break when subjected to impact loads, which limits their widespread application in complex working conditions. To solve these problems, composite materials of ceramics and metals have become a research hotspot, hoping to obtain new wear-resistant materials with excellent performance by complementing the advantages of the two.

[0003] There are many difficulties in the current ceramic preform preparation technology. Traditional methods make it difficult to accurately control the microstructure of the preform, resulting in uneven pore distribution, obstructed metal liquid penetration, many pores and defects inside the composite material, and greatly reduced bonding strength and overall performance; the preform strength is insufficient, and it is easy to deform and collapse under the high temperature and high pressure of metal liquid casting, and the molding accuracy and composite material quality cannot be guaranteed; the metal liquid and the ceramic preform have poor wettability, poor interface bonding, and interface peeling is prone to occur during use, shortening the service life of the composite material. Summary of the Invention

[0004] The purpose of the present invention is to provide a ceramic preform, a preparation method and a wear-resistant part thereof. The ceramic preform is prepared by freeze casting technology. By optimizing the process and parameters, the microstructure is precisely controlled to achieve uniform pore distribution and a honeycomb structure, providing a good channel for the infiltration of molten metal, improving wettability and interfacial bonding strength, and at the same time enhancing the strength and stability of the preform. It maintains a good shape and structure during molten metal casting, effectively improving the quality and reliability of the composite material, meeting the urgent demand for wear-resistant materials in the industrial field, and solving the problem of poor bonding between molten metal and ceramic preform.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present invention discloses a method for preparing a ceramic preform, comprising the following steps:

[0007] Step 1: dissolving the ceramic powder in distilled water and then acid washing it, then neutralizing it with ammonia water to neutrality, drying it after solid-liquid separation, and then performing oxidation roasting treatment to obtain rounded ceramic powder;

[0008] Step 2: Mix the solvent, binder, dispersant, and regulator in proportion and perform magnetic stirring, then add the rounded ceramic powder in batches for ball milling to obtain a ceramic slurry;

[0009] Step 3: Inject the ceramic slurry into a freezing mold with the lower surface temperature of -35°C to -25°C, keep the upper surface temperature of the freezing mold at room temperature of 15 - 25°C, freeze for 8 - 12 min, and at the same time adjust the lower surface temperature of the freezing mold at a cooling rate of 0.5 - 2°C / min to obtain a preform embryo;

[0010] Step 4: Freeze-dry the preform embryo under a vacuum of 8 - 12 Pa and a temperature of -40°C to -50°C for 20 - 28 h to form an embryo of a three-dimensional network interpenetrating preform with honeycomb-like pores;

[0011] Step 5: Sinter the freeze-dried embryo to obtain a ceramic preform.

[0012] Further, the specific operation method of Step 1 is: dissolve the ceramic powder in distilled water, pickle it with hydrochloric acid with a mass fraction of 5 - 15% until the solution is acidic, ultrasonically clean it and then neutralize it to neutral with ammonia water, separate the solid and liquid and dry it, and calcine it at 900 - 1100°C for 0.5 - 1 h to obtain the rounded ceramic powder;

[0013] Preferably, the dosage ratio of the ceramic powder to distilled water is 1 g:20 mL.

[0014] Preferably, the mass fraction of the hydrochloric acid is 10%.

[0015] Preferably, the determination method for the solution to be acidic is: determine it using pH test paper.

[0016] Preferably, the frequency of the ultrasonic cleaning is 20 - 40 kHz, the time is 0.5 - 1 h, and more preferably, ultrasonic cleaning is performed at 30 kHz for 45 min.

[0017] Preferably, the method of solid-liquid separation is: let it stand until it is completely stratified.

[0018] Preferably, the drying method is: dry it in an oven at 100°C for 2 h.

[0019] Further, in Step 1, the ceramic powder is SiC, Al2O3, ZrO2, TiC, ZrN, ZTA ceramic powder, and / or; the particle size of the ceramic powder is 1 - 3 um.

[0020] Further, in Step 2, the weight ratio of the solvent to the rounded ceramic powder is 100:(30 - 60), and the dosages of the binder, dispersant, and regulator respectively account for 0.5 - 2%, 0.8 - 2%, and 0.1 - 1.5% of the weight of the rounded ceramic powder;

[0021] Preferably, the weight ratio of the solvent to the rounded ceramic powder is 100:(30 - 60), and the dosages of the binder, dispersant, and regulator all account for 1% of the weight of the rounded ceramic powder.

[0022] Further, the solvent is tert-butanol, the binder is sodium silicate, the dispersant is polyvinyl alcohol, and the regulator is polyethylene glycol.

[0023] Further, in Step 2, the rotation speed of the magnetic stirring is 300 r / min, and the time is 20 min.

[0024] Further, in Step 2, the ball milling conditions are as follows: using zirconia grinding balls, ball milling for 20 - 28 h with a ball-to-material ratio of 20:1, more preferably 25 h.

[0025] Further, the specific operation method of Step 4 is as follows: putting the freeze-dried green body into a muffle furnace, sintering at a temperature of 1250 - 1350 °C for 1.5 - 2.5 h in an air atmosphere, and obtaining a ceramic preform after cooling with the furnace;

[0026] Preferably, the sintering temperature is 1300 °C, and the sintering time is 2 h.

[0027] In a second aspect, the present invention discloses a ceramic preform, which is obtained by the preparation method of the ceramic preform as described above.

[0028] In a third aspect, the present invention further discloses a wear-resistant part, which includes the ceramic preform as described above and a metal material compounded with the ceramic preform.

[0029] Further, the metal material includes at least one of high-chromium cast iron, high-manganese steel, low-alloy wear-resistant cast steel, and medium-alloy wear-resistant cast steel.

[0030] Further, the preparation method of the wear-resistant part is as follows: compounding the ceramic preform and the metal material by a non-pressure casting infiltration method;

[0031] Preferably, the operation method of the non-pressure casting infiltration is as follows: placing the ceramic preform at a preset position in the sand mold cavity, then preheating the internal temperature of the sand mold cavity to 100 - 600 °C, and then pouring the metal liquid at a temperature of 1450 - 1500 °C into the sand mold cavity, and removing the sand mold cavity after cooling to obtain the wear-resistant part.

[0032] Advantages of the present invention:

[0033] (1) The present invention uses a directional solidification technique to prepare a three-dimensional network interpenetrating preform with honeycomb-shaped pores, which will not deform during the casting of molten metal, and provides a better channel for the infiltration of molten metal, further enhancing the performance of the composite material; compared with the preforms obtained by traditional preparation methods, the ceramic preforms prepared by the present invention have significantly improved stability and composite effect during the casting of molten metal; the reasonable application of freeze-drying and sintering processes effectively maintains the microstructure of the preform, and the performance stability is significantly enhanced.

[0034] (2) The present invention configures the position and size of the ceramic preform according to the actual working conditions and wear conditions of the wear-resistant part, can achieve precise control of the wear resistance of the wear-resistant part, can meet the use requirements under different working conditions, and the pouring of molten metal is carried out under normal pressure, non-pressure or negative pressure, which has significant economic benefits and practical value. Compared with traditional wear-resistant parts, the wear-resistant parts of the present invention have a longer service life, and the service life is 3 to 6 times that of traditional single-metal wear-resistant materials. Brief Description of the Drawings

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] Figure 1 is a schematic structural diagram of the freezing device in Embodiment 1 of the present invention;

[0037] Figure 2 is a schematic structural diagram of the ceramic preform in Embodiment 2 of the present invention;

[0038] Figure 3 is a schematic structural diagram of the honeycomb-shaped pores in the ceramic preform of Embodiment 2 of the present invention;

[0039] Figure 4 is a schematic structural diagram of the hammer head wear-resistant part in Embodiment 5 of the present invention.

[0040] Reference Numerals: 100, ceramic preform; 1001, cylindrical hole; 1002, honeycomb-shaped pore; 101, preform mold; 102, refrigerating copper plate; 103, temperature measuring element; 104, heat insulating material; 105, heat conducting plate; 200, hammer head wear-resistant part. Detailed Embodiments

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] In the experimental methods of the following embodiments, unless otherwise specified, they are all conventional methods, carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. The materials used in the following embodiments, unless otherwise specified, can all be obtained commercially.

[0043] Example 1

[0044] This embodiment discloses a freezing device. Please refer to Figure 1 , the freezing device includes a ceramic preform mold 101, which is wrapped with a layer of thermal insulation material 104 on the outside; a refrigeration copper plate 102 is provided below the preform mold 101, a temperature measuring element 103 is provided inside the refrigeration copper plate 102, and a heat conducting plate 105 is provided below the refrigeration copper plate 102. The size of the preform mold 101 is 20 cm in diameter and 4 cm in height, and its interior is used to form a ceramic preform 100.

[0045] Example 2

[0046] This embodiment provides a ceramic preform, which is prepared by the following steps:

[0047] Step 1: Take 100 g of alumina ceramic powder with a particle size range of 1 - 3 μm, place it in a beaker, add 2000 mL of distilled water and stir evenly; perform pickling with 10% dilute hydrochloric acid. During the pickling process, use pH test paper to detect until the solution becomes acidic; then, transfer the solution into an ultrasonic cleaner and clean it at 30 Hz for 40 min to remove impurities; after cleaning, neutralize with ammonia water until the solution is neutral, then let it stand for precipitation for solid-liquid separation, and finally dry the separated powder in an oven at 100 °C for 2 h; roast the dried powder in a muffle furnace at 1000 °C for 40 min to blunt the sharp corners of the particles and make its surface round, obtaining 96.5 g of rounded ceramic powder;

[0048] Step 2: Mix 482.5 g of tert-butanol, 0.97 g of sodium silicate, 0.97 g of PVA, and 0.97 g of polyethylene glycol, place them in a magnetic stirrer, and stir at a speed of 300 r / min for 20 min to make them fully uniform. During this period, add the rounded ceramic powder in 3 equal amounts, and finally put it into a ball mill and ball mill it with zirconia grinding balls at a ball-to-material ratio of 20:1 for 25 h to finally obtain a uniform ceramic slurry.

[0049] Step 3: Inject the prepared ceramic slurry into the preform mold 101 of Example 1. The temperature of the refrigeration copper plate 102 is -30 °C, and the upper surface of the preform mold 101 is maintained at a room temperature environment of 20 °C, and directionally freeze for 10 min. During the freezing process, precisely control the cooling rate of the refrigeration copper plate 102 to be 1 °C / min, and finally form a three-dimensional network interpenetrating preform embryo with honeycomb-like pores;

[0050] Step 4: Place the prefabricated embryo into a freeze dryer, and freeze-dry the green body for 24 h in an environment with a vacuum degree of 10 Pa and a temperature of -50 °C to remove the solvent in the embryo and maintain the structure of the embryo;

[0051] Step 5: Place the freeze-dried embryo into a vacuum atmosphere tube furnace, heat it to 1300 °C at a heating rate of 5 °C / min in an air atmosphere, hold the temperature for 2 h, and then cool it with the furnace to obtain the ceramic preform 100 as shown in Figure 2 Figure 100.

[0052] Please refer to Figure 2-3 , a plurality of cylindrical holes 1001 are provided on the surface of the ceramic preform 100. The plurality of cylindrical holes 1001 are formed by the shaping structure inside the preform mold 101. It should be noted that the hole structure on the ceramic preform 100 is not limited to the cylindrical shape in this embodiment. In other embodiments, the hole structure can also be set to a hexagonal prism shape, an octagonal prism shape, etc. according to requirements; when using this type of structure, when subjected to an external force, the matrix can provide the maximum support for its side; there are a large number of honeycomb-like pores 1002 between the particles of the ceramic preform 100 body, and these pores can provide a good channel for the infiltration of molten metal.

[0053] Example 3

[0054] This example provides a ceramic preform, which is prepared by the following steps:

[0055] Compared with Example 2, the only difference is that: in Step 4, the vacuum degree is 8 Pa, the temperature is -40 °C, and the freeze-drying time is 28 h, and other steps and conditions remain the same; finally, a ceramic preform is obtained.

[0056] Example 4

[0057] This example provides a ceramic preform, which is prepared by the following steps:

[0058] Compared with Example 2, the only difference is that: in Step 4, the vacuum degree is 12 Pa, the temperature is -50 °C, and the freeze-drying time is 20 h, and other steps and conditions remain the same; finally, a ceramic preform is obtained.

[0059] Comparative Example 1

[0060] This comparative example provides a ceramic preform, which is prepared by the following steps:

[0061] Compared with Example 2, the only difference is that: Step 4 is cancelled, and other steps and conditions remain the same; finally, a ceramic preform is obtained.

[0062] Example 5

[0063] This embodiment discloses a hammer wear-resistant part, which is prepared through the following steps:

[0064] Please refer to Figure 4 , place two ceramic preforms 100 of Embodiment 2 at preset positions in the sand mold cavity, then preheat the internal temperature of the sand mold cavity to 300 °C, and then pour high manganese steel liquid at a temperature of 1480 °C into the sand mold cavity. After cooling, remove the sand mold cavity to obtain the hammer wear-resistant part 200. The two ceramic preforms 100 are respectively located at both ends (key easily worn parts) of the head of the hammer wear-resistant part 200.

[0065] The honeycomb-shaped pores 1002 in the ceramic preform 100 provide a good channel for the infiltration of high manganese steel liquid, significantly improving the wettability between the high manganese steel liquid and the ceramic preform 100, so that the hammer wear-resistant part 200 formed after their combination has excellent wear resistance and toughness.

[0066] Embodiment 6

[0067] This embodiment discloses a hammer wear-resistant part, which is prepared through the following steps:

[0068] Compared with Embodiment 5, the difference is only that the ceramic preform 100 of Embodiment 2 is replaced with the ceramic preform of Embodiment 3, and other steps and conditions remain the same, and finally a hammer wear-resistant part is obtained.

[0069] Embodiment 7

[0070] This embodiment discloses a hammer wear-resistant part, which is prepared through the following steps:

[0071] Compared with Embodiment 5, the difference is only that the ceramic preform 100 of Embodiment 2 is replaced with the ceramic preform of Embodiment 4, and other steps and conditions remain the same, and finally a hammer wear-resistant part is obtained.

[0072] Comparative Example 2

[0073] This comparative example discloses a hammer wear-resistant part, which is prepared through the following steps:

[0074] Compared with Embodiment 5, the difference is only that the ceramic preform 100 of Embodiment 2 is replaced with the ceramic preform of Comparative Example 1, and other steps and conditions remain the same, and finally a hammer wear-resistant part is obtained.

[0075] Perform mechanical property tests on the hammer wear-resistant parts corresponding to Embodiments 5-7 and Comparative Example 2, including wear resistance and deformation strength. The test methods are as follows.

[0076] Wear resistance: Considering the large impact on the hammer head in the actual service environment, the impact abrasive wear test was used to test its wear resistance; the composite material and the high manganese steel matrix were made into specimens with dimensions of 10mm×10mm×30mm and placed on the upper part of the testing machine, and quenched alloy steel (Cr12MoV, hardness 58HRC) was used as the corresponding specimen in the lower part. The abrasive was quartz sand with an average particle size of 0.1mm; the feeding speed, impact frequency, impact time, and impact energy were set to 50kg / h, 150 times / min, 60min, and 1J respectively; its wear resistance was calculated by the following formula: ε = ΔV m / ΔV c ; where ε is the relative wear resistance; ΔV m is the wear volume of the high manganese steel matrix; ΔV c is the wear volume of the composite material; ε is the average value of three repeated impact wear tests.

[0077] Deformation strength: A three-point bending test was carried out on the composite material specimen. The specimen was placed stably on two supports, and a load was applied at the midpoint above the two supports to cause the bending specimen to generate bending stress and deformation until the specimen fractured; the specimen size was 10mm×5mm×30mm, the span was 25mm, and the load loading rate was set to 0.1mm / min; the deformation strength formula is as follows: σ = 3FL / 2bh 2 ; where σ is the deformation strength (MPa), F is the load (N), L is the span (mm), b is the specimen width (mm), and h is the specimen height (mm).

[0078] The test results are listed in Table 1 as follows:

[0079] Table 1

[0080]

[0081]

[0082] By analyzing the data in Table 1, it can be known that compared with Comparative Example 2, the hammer wear parts of Examples 5-7 have stronger wear resistance and deformation strength; this shows that the wear parts prepared by combining the ceramic preform and the metal material of the present invention have stronger mechanical properties.

[0083] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation and specific orientation structure and operation. Therefore, it should not be construed as a limitation of the present invention. In addition, "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0084] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] The above has described in detail one embodiment of the present invention, but the content described is only the preferred embodiment of the present invention and cannot be considered as used to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for preparing a ceramic preform, characterized in that, It includes the following steps: Step 1: Dissolve the ceramic powder in distilled water, then perform pickling, neutralize it with ammonia water until neutral, separate the solid from the liquid, dry it, and then perform oxidative roasting treatment to obtain rounded ceramic powder; Step 2: Mix the solvent, binder, dispersant, and regulator in proportion and perform magnetic stirring, then add the rounded ceramic powder in batches for ball milling to obtain ceramic slurry; Step 3: Inject the ceramic slurry into a freezing mold with a lower surface temperature of -35°C to -25°C. The upper surface temperature of the freezing mold is maintained at room temperature of 15 - 25°C, and freeze for 8 - 12 minutes. At the same time, adjust the lower surface temperature of the freezing mold at a cooling rate of 0.5 - 2°C / min to obtain a preform embryo; Step 4: Freeze-dry the preform embryo under a vacuum of 8 - 12 Pa and a temperature of -40°C to -50°C for 20 - 28 hours to form an embryo of a three-dimensional network interpenetrating preform with honeycomb-like pores; Step 5: Sinter the freeze-dried embryo to obtain a ceramic preform.

2. The preparation method of the ceramic preform according to claim 1, characterized in that, The specific operation method of Step 1 is: Dissolve the ceramic powder in distilled water, pickle it with hydrochloric acid with a mass fraction of 5 - 15% until the solution is acidic, perform ultrasonic cleaning, neutralize it with ammonia water until neutral, separate the solid from the liquid, dry it, and roast it at 900 - 1100°C for 0.5 - 1 hour to obtain rounded ceramic powder.

3. The method for preparing a ceramic preform according to claim 1, wherein, In Step 1, the ceramic powder is SiC, Al2O3, ZrO2, TiC, ZrN, ZTA ceramic powder, and / or; the particle size of the ceramic powder is 1 - 3 um.

4. The method for preparing a ceramic preform according to claim 1, wherein In Step 2, the weight ratio of the solvent to the rounded ceramic powder is 100:(30 - 60), and the dosages of the binder, dispersant, and regulator respectively account for 0.5 - 2%, 0.8 - 2%, and 0.1 - 1.5% of the weight of the rounded ceramic powder.

5. The preparation method of the ceramic preform according to claim 4, wherein, The solvent is tert-butanol, the binder is sodium silicate, the dispersant is polyvinyl alcohol, and the regulator is polyethylene glycol.

6. The method for preparing the ceramic preform according to claim 1, characterized in that, In Step 2, the ball milling conditions are: Use zirconia grinding balls to ball mill for 20 - 28 hours at a ball-to-material ratio of 20:

1.

7. The preparation method of the ceramic preform according to claim 1, wherein, The specific operation method of Step 4 is: Put the freeze-dried embryo into a muffle furnace, sinter it at a temperature of 1250 - 1350°C for 1.5 - 2.5 hours in an air atmosphere, and cool it with the furnace to obtain a ceramic preform.

8. A ceramic preform, characterized in that, It is prepared by the preparation method of the ceramic preform according to any one of claims 1 - 7.

9. A wear-resistant part, characterized in that, It includes the ceramic preform according to claim 8 and a metal material composite with the ceramic preform.

10. The wear-resistant part according to claim 9, characterized in that, The preparation method of the wear-resistant part is: Composite the ceramic preform and the metal material by a non-pressure casting infiltration method.

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