A kind of erosion-resistant carburized YSZ-C ceramic material and its preparation method

Abstract

This invention relates to a cavitation-resistant carburized YSZ-C ceramic material and its preparation method. The material is characterized by the use of graphite molds, graphite paper, and a vacuum hot press furnace to sinter a black YSZ-C ceramic block with uniform carbon permeation. The preparation method uses YSZ powder containing oxygen vacancies as raw material, adding distilled water or anhydrous ethanol as the ball milling medium, and ball milling the powder raw material in a ball mill jar. The ball-milled powder is then pressed into shape and hot-pressed for sintering. During the sintering process, graphite molds, graphite pads, and high-purity graphite paper are used to provide the carbon source, and the sintering temperature reaches 1450~1650℃. During vacuum sintering, carbon elements with atomic radii close to oxygen can uniformly enter the interior of the YSZ grains through oxygen vacancies under high temperature. After sintering, cooling yields the target product. Testing shows that this carburized YSZ-C ceramic block material has significantly improved cavitation resistance compared to conventional YSZ ceramic block materials, making it more suitable for use as a material for flow-through components such as ball valves.

Description

Technical Field

[0001] This invention relates to a cavitation-resistant carburized YSZ-C bulk ceramic material, and more particularly to a black carburized YSZ-C bulk ceramic with cavitation resistance and its preparation method, belonging to the technical field of structural ceramics and cavitation-resistant ceramic material preparation. Background Technology

[0002] Material failure during service has always been a major factor restricting the upgrading of core technologies in high-end manufacturing industries. Among these, cavitation damage (or cavitation) in high-speed flow components such as turbine ball valves, water turbines, pumps, and propellers poses a significant threat. For example, cavitation damage to water turbines, a core component of hydropower generation, results in an annual power generation loss exceeding 128 billion kilowatt-hours; cavitation damage to propellers greatly affects the stability and reliability of ship navigation; and ball valves in various chemical plant pipelines are prone to sealing leaks due to cavitation damage, introducing significant uncertainties to safe production. The difficulty in solving cavitation problems stems from the fact that the combined effects of the shock waves, microjets, and instantaneous high temperatures generated by cavitation collapse almost invariably cause severe fatigue spalling or even breakdown fractures in traditional materials. Therefore, developing new materials with excellent cavitation resistance is of great significance for the upgrading and optimization of various flow components.

[0003] Ceramic materials, due to their high strength, high hardness, high melting point, corrosion resistance, and chemical stability, have been widely used in aerospace, shipbuilding, hydropower, petrochemical, and biomedical fields, and have become one of the research hotspots for cavitation erosion-resistant materials in recent years. Currently, common ceramic materials used for cavitation erosion resistance include alumina, silicon nitride, zirconium oxide, and glass mica. The literature "Ceram. Int., 1994, 20(3): 201-9." studied the cavitation erosion behavior of various ceramic materials in distilled water and found that they are more resistant to cavitation erosion than metals. Among them, zirconium oxide has multiple toughening mechanisms such as phase transformation toughening, stress microcrack toughening, and ferroelastic toughening, and exhibits high strength and relatively good toughness among many ceramic materials, and is considered one of the most promising cavitation erosion-resistant ceramic materials. However, pure zirconium oxide is prone to cracking due to volume changes caused by phase transformation during high-temperature sintering, making it difficult to obtain complete ceramic blocks, which greatly limits its application. Although adding yttrium oxide (Y₂O₃) can stabilize the phase structure of zirconia (ZrO₂) during high-temperature sintering to some extent and improve the yield, the study in "Wear, 2013, 300(1-2):163–8." found that the mechanical properties, especially the toughness, of yttrium oxide-stabilized zirconia (YSZ) ceramics are still poor, and they are still prone to brittle spalling under continuous impact from cavitation loads. Therefore, how to further improve the mechanical and cavitation erosion resistance properties of YSZ has become an urgent problem to be solved in the fields of fluid machinery and materials science. Summary of the Invention

[0004] To address the problems existing in the above-mentioned background technology, this invention discloses a cavitation-resistant carburized YSZ-C bulk ceramic material and its preparation method. This material is not only easier to fire, but also has significantly higher comprehensive mechanical properties. Furthermore, it changes the contact angle with water, thus improving the cavitation resistance performance by 1 to 2 orders of magnitude compared to traditional YSZ materials, making it a significant advantage as a protective material.

[0005] The technical solution adopted in this invention is as follows:

[0006] I. Preparation of Cavitation-Resistant Carburized YSZ-C Bulk Ceramic Material

[0007] 1. Select YSZ (yttrium-stabilized zirconium oxide) powder as raw material, pour it into a ball mill jar, and then add 2 to 3 times the mass of YSZ powder of deionized water or ethanol as wet grinding medium to the ball mill jar. Ball mill at 200 to 500 r / min for 20 to 50 h, then dry and grind to obtain powder.

[0008] The purpose of ball milling is to cause the powder and the grinding balls in the jar to collide and rub against each other at high speed, so as to achieve the functions of crushing, grinding and dispersing the sample.

[0009] Drying involves placing the slurry obtained after ball milling into a blower drying oven for drying; grinding involves placing the dried powder in a grinding mortar or other grinding tools and grinding it with tools such as an agate grinding rod.

[0010] Preferably, the purity of the YSZ powder is ≥99%, and the particle size range is 20nm~200μm.

[0011] Preferably, the yttrium oxide content in the YSZ powder is 1 mol% to 10 mol%.

[0012] Preferably, the wet grinding medium is 99% pure deionized water or anhydrous ethanol.

[0013] 2. The obtained target powder is pressed into a green body. The obtained target green body is then placed into a graphite mold in the following order: graphite pad - graphite paper - target green body - graphite paper - target green body - graphite paper. Hot pressing and sintering are then performed. After sintering, the material is cooled to obtain the target product, carburized YSZ-C bulk ceramic material. A vacuum is applied during the hot pressing and sintering process, with a vacuum degree ≤10. -1 Pa, sintering pressure is 10~30 MPa, sintering temperature is 1200~1650 ℃.

[0014] Preferably, the carbon content in the graphite paper and graphite pad is ≥99%.

[0015] The preferred hot pressing sintering process and process parameters are as follows:

[0016] 1) Heating process: The sample is rapidly heated to 800~1100 ℃ in the furnace at a rate of 10~15℃ / min and subjected to sintering pressure of 10~15 MPa;

[0017] 2) Heating and sintering process: The sample is heated to 1200~1450℃ in the furnace at a rate of 5~15℃ / min and subjected to a sintering pressure of 20~25MPa for a total of 20~50min. Then, the temperature is increased to 1450~1650℃ at a rate of 1~5℃ / min and subjected to a sintering pressure of 25~30MPa for a total of 90~120min.

[0018] 3) Self-controlled cooling process: Cool down to 1100~1400℃ at a rate of 5~10℃ / min, and then maintain the sintering pressure at 10~15 MPa for 15~30min. Then, maintain the sintering pressure at 10MPa for 20~50min. After cooling to room temperature, black cavitation resistant YSZ-C bulk ceramic material can be obtained.

[0019] The synthesis mechanism of this invention: Yttrium-stabilized zirconium oxide (YSZ) powder is selected as the raw material, wherein the doping content of yttrium oxide is 1 mol%~10 mol%, because Y 3+ and Zr 4+ The number of oxygen atoms distributed around the ion varies in Y. 3+ Doping with metal Zr 4+ After lattice positioning, a large number of oxygen vacancies are formed in YSZ. Since the radius of a carbon atom is 0.077 nm, which is very close to the radius of an oxygen atom (0.074 nm), the vacuum hot-pressing sintering technology used in this invention, along with the oxygen-free and sufficiently carbon atmosphere provided by graphite molds, graphite pads, and graphite paper, creates favorable conditions for carbon elements to diffuse into YSZ through oxygen vacancies. More importantly, this invention employs an ultra-high temperature sintering temperature of 1450~1650℃, providing carbon atoms with sufficiently high migration potential energy, facilitating the overcoming of migration energy barriers and enabling uniform diffusion within the YSZ bulk. The uniformly distributed heterogeneous carbon atoms not only prevent excessive growth of YSZ grains but also reduce residual stress and brittleness, greatly improving the sintering success rate of the bulk material. Furthermore, the preferred grinding and sintering processes of this invention also play a significant role in preparing carburized YSZ-C bulk ceramics with excellent structure and performance: if the ball mill does not reach the predetermined speed and time, the powder will not be sufficiently broken down, resulting in uneven grain growth in the sintered sample and affecting its performance; if the sintering temperature is too low, the ceramic bulk will not be densely sintered, and the carburized layer will be shallow, small in quantity and uneven; if the holding time is too long, the grains will grow too large, resulting in poor performance.

[0020] II. Characterization and Properties of Cavitation-Resistant Carburized YSZ-C Ceramic Bulk Materials

[0021] 1. Structural characterization

[0022] Figure 2 The YSZ-C bulk ceramic synthesized in this invention and conventional YSZ bulk ceramics show that YSZ-C is a typical black bulk material, which is quite different from conventional YSZ ceramics, which are usually white.

[0023] Figure 3 The image shows the Raman spectrum of the YSZ-C ceramic material prepared in this invention. A distinct carbon peak is present, located approximately at 1360 cm⁻¹. -1 The D peaks on the left and right are located at approximately 1570cm. -1 The G peaks around the left and right indicate that the method provided by this invention can indeed allow carbon to diffuse into YSZ in elemental form.

[0024] Figure 4 This is a SEM image of the thermally etched surface of the YSZ-C synthesized in this invention. Figure 5 The elemental statistics of the EDS energy spectrum of YSZ-C are shown below. Figure 6 The images show the TEM morphology and corresponding elemental distribution patterns inside YSZ-C. These data clearly demonstrate that the carbon atom distribution in the YSZ-C material prepared in this invention is extremely uniform, with a large amount of carbon present throughout the entire material, accounting for 13.33% by weight. This further indicates that carbon atoms have been efficiently infiltrated into YSZ through oxygen vacancies. Furthermore, the YSZ-C ceramic grain size is relatively uniform, with a maximum grain size of less than 3 μm, indicating that the infiltrated heterogeneous C atoms have a good inhibitory effect on grain growth. This is beneficial for improving the mechanical properties and cavitation erosion resistance of the ceramic material.

[0025] 2. Performance Evaluation

[0026] 2.1 Mechanical Properties

[0027] 1) The hardness of YSZ-C and conventional YSZ ceramic materials was tested using a Vickers microhardness tester. The test conditions were: a load of 300g and a loading duration of 5s. The results showed that the microhardness of YSZ-C was 1487.50±29.72 HV. 300g It is higher than YSZ's 1395.70±8.89 HV. 300g .

[0028] 2) The nanohardness and elastic modulus of YSZ-C and YSZ ceramic materials were tested using a nanoindenter. The test conditions were: 5 test points were randomly selected, a load of 10 mN was applied, and the loading duration was 10 s. The results showed that the H of YSZ-C... IT and H 3 / E* 2The values ​​are 14.56 GPa and 0.111 respectively, which are significantly higher than those of YSZ (3.15 GPa and 0.003), indicating that the YSZ-C ceramic of this invention has significantly higher hardness and toughness than the traditional YSZ.

[0029] The improved toughness of the YSZ-C novel ceramic is also reflected in the morphology of its Vickers indentation, such as... Figure 7 As shown, unlike the obvious cracks at the edges of the YSZ indentation, no cracks were observed around the YSZ-C indentation, further proving that carburizing can significantly improve the ability of ceramic materials to resist fatigue cracking.

[0030] 2.2 Hydrophilicity

[0031] The water contact angles of YSZ-C and YSZ ceramic blocks were measured using a DSA100 contact angle meter (KRUSS GmbH, Germany). Each test used a 5 μL water droplet, and each sample was measured three times, with the average value taken. The results showed that the water contact angle of YSZ-C was 70.31°, significantly higher than that of YSZ (62°), indicating that the ceramic surface of this invention is more hydrophobic. This is mainly because the inclusion of carbon reduces the surface energy of YSZ-C. The hydrophobic and aerophilic surface can better prevent the formation and collapse of cavitation bubbles around it, and the gas film adsorbed on the material surface can effectively mitigate the impact of shock waves and microjets generated by cavitation collapse on the ceramic surface. Therefore, this is highly beneficial for improving the material's resistance to cavitation erosion.

[0032] 2.3 Cavitation performance

[0033] Cavitation performance was tested in deionized water using an ultrasonic cavitation machine. Before the experiment, the polished sample was fixed on the sample stage below the ultrasonic tip, 12±4 mm above the liquid surface. The upper sample was made of stainless steel with a diameter of 15.9 mm, coaxially mounted with the sample to be tested, with a distance of approximately 0.5±0.01 mm between them. The water bath circulation system maintained the temperature of the deionized water within the range of 25±2 ℃, the vibration frequency was 20 kHz, and the amplitude was 50 μm (peak-to-peak). Before and after the experiment, the sample was ultrasonically cleaned in ethanol solution for 3 min each time. Then, the mass loss of the sample was measured and recorded using an analytical balance with an accuracy of 0.1 mg.

[0034] The results showed that the cavitation incubation period of the YSZ-C ceramic material prepared by the present invention was as long as 9 h, while the cumulative mass loss after 10 h of cavitation was only 0.1 mg, which was 1 to 2 orders of magnitude lower than that of the traditional zirconia ceramic "Ceram. Int., 1994, 20(3): 201-9." and the YSZ ceramic prepared by Comparative Example 3, demonstrating extremely high resistance to cavitation.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] This invention utilizes the similarity in size between oxygen vacancies and carbon elements in YSZ material. By using graphite molds, graphite pads, and graphite paper, and through vacuuming, an "oxygen-free, carbon-rich" atmosphere is created in a hot press furnace. Heating to a sufficiently high temperature allows carbon atoms to acquire enough migration energy to overcome energy barriers and uniformly penetrate all grains and interfaces on the surface and within the YSZ, resulting in a uniformly colored black YSZ-C ceramic bulk material. This synthesis method has never been reported before; it is a completely new design by the inventor based on scientific principles. Furthermore, the YSZ powder and graphite paper used in this invention are simple, common, commercially available, readily available, and inexpensive. The vacuum hot press furnace used is also a commonly used piece of equipment for preparing ceramic bulk materials. More importantly, the black YSZ-C ceramic material prepared by this invention exhibits significantly improved hardness and toughness compared to YSZ, and is more hydrophobic and air-philic. Therefore, it can better resist the mechanical impact of cavitation collapse under cavitation conditions, with extremely slight fatigue spalling and excellent cavitation resistance. Therefore, the YSZ-C ceramic material prepared by this invention is expected to be widely used in the field of fluid machinery. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the mold and sample loading process in the sintering preparation of YSZ-C carburized ceramic material according to the present invention (① graphite pad, ② graphite paper, ③ target green body, ④ upper pressure rod).

[0038] Figure 2 Digital photographs of the YSZ-C bulk ceramic prepared for this invention and conventional YSZ bulk ceramic.

[0039] Figure 3 The Raman spectrum of the carburized YSZ-C ceramic material prepared according to the present invention.

[0040] Figure 4 This is a SEM image of the thermally etched surface of the carburized YSZ-C ceramic material prepared according to the present invention.

[0041] Figure 5 The image shows the elemental distribution of the carburized YSZ-C ceramic material prepared according to this invention using EDS energy dispersive spectroscopy.

[0042] Figure 6 The TEM morphology and corresponding elemental distribution diagrams of the carburized YSZ-C ceramic material prepared in this invention are shown.

[0043] Figure 7 Vickers indentation SEM images of the carburized YSZ-C (a) and conventional YSZ (b) prepared according to the present invention. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solution of the present invention, the preparation and properties of the carburized YSZ-C ceramic material of the present invention will be further explained below with reference to implementation examples.

[0045] Example 1

[0046] 1) Select 3 mol% yttrium oxide stabilized zirconium oxide (YSZ) powder with a purity ≥99% and a particle size range of 60~90 μm as raw material, weigh 100 g and pour it into a ball mill jar, add 200 g of deionized water as wet grinding medium; the ball mill speed is 400 r / min; the ball milling time is 36 h; dry the slurry obtained above in a forced-air drying oven at 150 ℃ for 3 h; finally, grind the dried powder using an agate mortar to obtain the powder required for sintering.

[0047] 2) Weigh 10 g of the dried target powder obtained in step 1), press it using a manual press at 14 MPa for 10 min to obtain a green body, and then process the obtained target green body according to... Figure 1 The sample was loaded in the order shown. The green body, graphite pad, and graphite paper were placed into a standard graphite mold measuring 25 mm × 25 mm × 1500 mm and then placed in a vacuum hot press furnace for hot pressing and sintering. Hot pressing and sintering process conditions: The atmosphere furnace was evacuated to ensure the vacuum reading was <10. -1 Pa; First, the heating process: the sample is rapidly heated to 1100 ℃ at a rate of 10 ℃ / min in the furnace and subjected to a sintering pressure of 12.5 MPa; second, the heating and sintering process: the sample is heated to 1400 ℃ at a rate of 10 ℃ / min in the furnace and subjected to a sintering pressure of 20 MPa for a total of 30 min, then heated to 1600 ℃ at a rate of 5 ℃ / min and subjected to a sintering pressure of 25 MPa for 100 min; 3) Next is the self-controlled cooling process: the sample is cooled to 1400 ℃ at a rate of 10 ℃ / min and held at a sintering pressure of 12.5 MPa for 20 min, then held at a sintering pressure of 10 MPa for another 30 min. After sintering, the sample is cooled in the furnace to obtain the target product, carburized YSZ-C bulk ceramic material.

[0048] 3) Properties of carburized YSZ-C bulk ceramic material: The appearance is uniformly black, and the microhardness is 1487.50±29.72 HV. 300g The cumulative cavitation mass loss after 10 hours of cavitation erosion was 0.1 mg, demonstrating excellent cavitation resistance.

[0049] Example 2

[0050] 1) Select 3 mol% yttrium oxide stabilized zirconium oxide (YSZ) powder with a purity ≥99% and a particle size range of 60~90μm as raw material, weigh 100 g and pour it into a ball mill jar, add 250 g of anhydrous ethanol as wet grinding medium; the ball mill speed is 500 r / min; the ball milling time is 36 h; dry the slurry obtained above in a forced-air drying oven at 150 ℃ for 3 h; finally, grind the dried powder using an agate mortar to obtain the powder required for sintering.

[0051] 2) Weigh 10 g of the dried target powder obtained in step 1), press it using a manual press at 14 MPa for 10 min to obtain a green body, and then process the obtained target green body according to... Figure 1 The sample was loaded in the order shown. The green body, graphite pad, and graphite paper were placed into a standard graphite mold measuring 25 mm × 25 mm × 1500 mm and then placed in a vacuum hot press furnace for hot pressing and sintering. Hot pressing and sintering process conditions: The atmosphere furnace was evacuated to ensure the vacuum reading was <10. -1 Pa; First, the heating process: the sample is rapidly heated to 1100 ℃ in the furnace at a rate of 10 ℃ / min and subjected to a sintering pressure of 12.5 MPa; second, the heating and sintering process: the sample is heated to 1400 ℃ in the furnace at a rate of 10 ℃ / min and subjected to a sintering pressure of 20 MPa for a total of 30 min, then heated to 1600 ℃ at a rate of 5 ℃ / min and subjected to a sintering pressure of 25 MPa for 100 min; 3) Next is the self-controlled cooling process: the temperature is lowered to 1400 ℃ at a rate of 10 ℃ / min and maintained at a sintering pressure of 12.5 MPa for 20 min, then maintained at a sintering pressure of 10 MPa for another 30 min. After sintering, the sample is cooled in the furnace to obtain the target product, carburized YSZ-C bulk ceramic material.

[0052] 3) Properties of carburized YSZ-C bulk ceramic material: The appearance is uniformly black, and the microhardness is 1459.10±26.05 HV. 300g The cumulative cavitation mass loss after 10 hours of cavitation erosion was 0.1 mg, demonstrating excellent cavitation resistance.

[0053] Example 3

[0054] 1) Select 3 mol% yttrium oxide stabilized zirconium oxide (YSZ) powder with a purity ≥99% and a particle size range of 60~90μm as raw material, weigh 100 g and pour it into a ball mill jar, add 250 g of anhydrous material as wet grinding medium; the ball mill speed is 400 r / min; the ball milling time is 24 h; dry the slurry obtained above in a forced-air drying oven at 150 ℃ for 3 h; finally, grind the dried powder using an agate mortar to obtain the powder required for sintering.

[0055] 2) Weigh 10 g of the dried target powder obtained in step 1), press it using a manual press at 16 MPa for 15 min to obtain a green body, and then process the obtained target green body according to... Figure 1 The sample was loaded in the order shown. The green body, graphite pad, and graphite paper were placed into a standard graphite mold measuring 25 mm × 25 mm × 1500 mm and then placed in a vacuum hot press furnace for hot pressing and sintering. Hot pressing and sintering process conditions: The atmosphere furnace was evacuated to ensure the vacuum reading was <10. -1 Pa; First, the heating process: the sample is rapidly heated to 1100 ℃ at a rate of 10 ℃ / min in the furnace and subjected to a sintering pressure of 12.5 MPa; second, the heating and sintering process: the sample is heated to 1400 ℃ at a rate of 10 ℃ / min in the furnace and subjected to a sintering pressure of 20 MPa for a total of 30 min, then heated to 1600 ℃ at a rate of 5 ℃ / min and subjected to a sintering pressure of 25 MPa for 100 min; 3) Next is the self-controlled cooling process: the sample is cooled to 1400 ℃ at a rate of 10 ℃ / min and held at a sintering pressure of 12.5 MPa for 20 min, then held at a sintering pressure of 10 MPa for another 30 min. After sintering, the sample is cooled in the furnace to obtain the target product, carburized YSZ-C bulk ceramic material.

[0056] 3) Properties of carburized YSZ-C bulk ceramic material: The appearance is uniformly black, and the microhardness is 1419.50±27.66 HV. 300g The cumulative cavitation mass loss after 10 hours of cavitation erosion was 0.6 mg, demonstrating excellent cavitation resistance.

[0057] Comparative Example 1

[0058] 1) Select ZrO2 powder with a purity of ≥99% and a particle size range of 80~100 nm as raw material.

[0059] 2) Weigh 10 g of the powder from step 1), press it at 14 MPa for 10 min using a manual press to obtain a green body, and then press the obtained green body according to... Figure 1The sample was loaded in the order shown. The green body, graphite pad, and graphite paper were placed into a standard graphite mold measuring 25 mm × 25 mm × 1500 mm and then placed in a vacuum hot press furnace for hot pressing and sintering. Hot pressing and sintering process conditions: The atmosphere furnace was evacuated to ensure the vacuum reading was <10. -1 The process involved several steps: First, the heating process: the sample was rapidly heated to 1100 °C at a rate of 10 °C / min in the furnace and subjected to a sintering pressure of 12.5 MPa. Second, the sintering process: the sample was heated to 1400 °C at a rate of 10 °C / min and subjected to a sintering pressure of 20 MPa for 30 min. Then, the sample was heated to 1600 °C at a rate of 5 °C / min and subjected to a sintering pressure of 25 MPa for 100 min. Third, the controlled cooling process: the sample was cooled to 1400 °C at a rate of 10 °C / min and held at a sintering pressure of 12.5 MPa for 20 min, then held at a sintering pressure of 10 MPa for another 30 min. After sintering, the sample was cooled in the furnace to obtain ZrO2 bulk ceramic material.

[0060] 3) Properties of ZrO2 bulk ceramic materials: The appearance is that of white ceramic blocks, which are very brittle and prone to cracking, making further experimental testing of mechanical properties and cavitation erosion resistance impossible. Since pure ZrO2 lacks oxygen vacancies, carbon cannot penetrate it at high temperatures, thus a uniformly carburized black ZrO2-C material cannot be obtained. This demonstrates that even if the sintering temperature and carburizing atmosphere conditions are exactly the same as in the examples, a carburized ceramic material with good cavitation erosion resistance cannot be obtained if the raw material types are not within the range specified in this invention.

[0061] Comparative Example 2

[0062] 1) Select 3 mol% yttrium oxide stabilized zirconium oxide (YSZ) powder with a purity ≥99% and a particle size range of 60~90 μm as raw material, weigh 100 g and pour it into a ball mill jar, add 200 g of deionized oil as wet grinding medium to the ball mill jar; the ball mill speed is 400 r / min; the ball milling time is 36 h; dry the slurry obtained above in a forced-air drying oven at 150 ℃ for 3 h; finally, grind the dried powder using an agate mortar to obtain the powder required for sintering.

[0063] 2) Weigh 10 g of the dried target powder obtained in step 1), press it at 14 MPa for 10 min using a manual press to obtain a green body. Then, pack the obtained target green body in the following order: molybdenum pad block - target green body - molybdenum pad block - target green body. Place it into a standard graphite mold with dimensions of 25 mm × 25 mm × 1500 mm and molybdenum sheets on all sides, and then place it in a vacuum hot press furnace for hot pressing sintering. Hot pressing sintering process conditions: The atmosphere furnace is evacuated to ensure that the vacuum reading is <10. -1 Pa; First, the heating process: the sample is rapidly heated to 1100 ℃ in the furnace at a rate of 10 ℃ / min and subjected to a sintering pressure of 12.5 MPa; second, the heating and sintering process: the sample is heated to 1400 ℃ in the furnace at a rate of 10 ℃ / min and subjected to a sintering pressure of 20 MPa for a total of 30 min, then heated to 1600 ℃ at a rate of 5 ℃ / min and subjected to a sintering pressure of 25 MPa for 100 min; 3) Next is the self-controlled cooling process: the sample is cooled to 1400 ℃ at a rate of 10 ℃ / min and held at a sintering pressure of 12.5 MPa for 20 min, then held at a sintering pressure of 10 MPa for another 30 min. After sintering, the sample is cooled in the furnace to obtain YSZ bulk ceramic material.

[0064] 3) Performance of YSZ bulk ceramic material: The ceramic blocks are extremely uneven in color, light gray. The blocks are prone to breakage due to numerous cracks, making further testing of mechanical properties and cavitation erosion resistance impossible. Because graphite pads and graphite paper were not used, a sufficient carbon atmosphere was lacking during high-temperature sintering. Therefore, even though YSZ contains oxygen vacancies and the sintering temperature is high enough, carbon cannot efficiently penetrate, resulting in a uniformly carburized black YSZ-C material. This demonstrates that even if the raw materials and sintering process are exactly the same as in the examples, a carburized ceramic material with good cavitation erosion resistance cannot be obtained if the carburizing atmosphere conditions are not within the range specified in this invention.

[0065] Comparative Example 3

[0066] 1) Select 7 mol% yttrium oxide stabilized zirconium oxide (YSZ) powder with a purity ≥99% and a particle size range of 80~100 nm as raw material.

[0067] 2) Weigh 10 g of the powder from step 1), press it at 14 MPa for 10 min using a manual press to obtain a green body, and then press the obtained green body according to... Figure 1The sample was loaded in the order shown. The green body, graphite pad, and graphite paper were placed into a standard graphite mold measuring 25 mm × 25 mm × 1500 mm and then placed in a vacuum hot press furnace for hot pressing and sintering. Hot pressing and sintering process conditions: The atmosphere furnace was evacuated to ensure the vacuum reading was <10. -1 The process involved two stages: First, a heating process: the sample was rapidly heated to 400 °C at a rate of 10 °C / min and subjected to a sintering pressure of 12.5 MPa. Then, the sample was heated to 1100 °C at a rate of 10 °C / min and subjected to a sintering pressure of 20 MPa, a process lasting 110 min. Next, a sintering process was performed: the sample was heated to 1400 °C at a rate of 10 °C / min and subjected to a sintering pressure of 25 MPa, a process lasting 150 min. After sintering, the sample was cooled in the furnace to obtain YSZ bulk ceramic material.

[0068] 3) Properties of YSZ bulk ceramic material: The appearance color is uneven gray, and the microhardness is 1395.70±8.89HV. 300g The cumulative cavitation mass loss of YSZ-C obtained in the example after 10 hours of cavitation erosion testing was 23.8 mg, significantly higher than that of YSZ-C in the example by tens to hundreds of times. Due to insufficient sintering temperature, even with sufficient carbon source, carbon atoms could not acquire enough migration energy to uniformly diffuse into YSZ containing more oxygen vacancies. This indicates that even if the raw material contains more oxygen vacancies and the carbon source is sufficient, a carburized ceramic material with good cavitation erosion resistance cannot be obtained if the sintering temperature is not within the required range of this invention.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a cavitation-resistant carburized YSZ-C ceramic material, characterized in that, Includes the following steps: 1) Select YSZ powder as raw material, pour it into a ball mill jar, add 2 to 3 times the mass of YSZ powder of deionized water or anhydrous ethanol as wet grinding medium, ball mill at 200 to 500 r / min for 20 to 50 hours, dry it, and then grind it to obtain powder raw material. 2) Press the target powder obtained in step 1) into a green body, and then put the target green body into a graphite mold in the order of graphite pad block-graphite paper-target green body-graphite paper-target green body-graphite paper for hot pressing sintering. After sintering, cool to obtain the target product carburized YSZ-C bulk ceramic material. The hot pressing sintering process consists of the following steps: The process consists of three stages: First, a heating process: The sample is heated to 800-1100℃ in the furnace at a rate of 10-15℃ / min and subjected to a sintering pressure of 10-15MPa for a total of 90-120 minutes. Second, a heating and sintering process: The sample is heated to 1200-1450℃ in the furnace at a rate of 5-15℃ / min and subjected to a sintering pressure of 20-25MPa for a total of 20-50 minutes. Then, the sample is heated to 1450-1650℃ at a rate of 1-5℃ / min and subjected to a sintering pressure of 25-30MPa for a total of 90-120 minutes. Finally, a self-controlled cooling process: The sample is cooled to 1100-1400℃ at a rate of 5-10℃ / min and held at a sintering pressure of 10-15MPa for 10-30 minutes, then held at a sintering pressure of 10MPa for another 20-50 minutes.

2. The preparation method of the cavitation-resistant carburized YSZ-C ceramic material as described in claim 1, characterized in that, In step 1), the purity of YSZ powder is ≥99%, and the particle size range is 20nm~200μm.

3. The method for preparing a cavitation-resistant carburized YSZ-C ceramic material as described in claim 1, characterized in that, In step 1), the yttrium oxide content in the YSZ powder is 1 mol% to 10 mol%.

4. The preparation method of the cavitation-resistant carburized YSZ-C ceramic material as described in claim 1, characterized in that, In step 1), the wet grinding medium is 99% pure deionized water or anhydrous ethanol.

5. The method for preparing a cavitation-resistant carburized YSZ-C ceramic material as described in claim 1, characterized in that, In step 2), the carbon content in the graphite pad and graphite paper is ≥99%.

6. The method for preparing a cavitation-resistant carburized YSZ-C ceramic material as described in claim 1, characterized in that, In step 2), the vacuum level is controlled at 10 during the hot pressing sintering process. -1 Below Pa.

7. A cavitation-resistant carburized YSZ-C ceramic material prepared by the method described in claim 1.

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