An alumina-based valve core ceramic material and its preparation method

Abstract

This invention relates to the field of ceramic materials, specifically to an alumina-based valve core ceramic material and its preparation method. By weight, it comprises the following components: 80-100 parts alumina, 15-30 parts zirconium oxide, 4-8 parts boron-doped graphene, and 1-5 parts sintering aid. The ceramic material prepared by this invention has good properties and can meet the performance requirements of valve core materials.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials, specifically to an alumina-based valve core ceramic material and its preparation method. Background Technology

[0002] Valves are a general term for mechanical products with movable mechanisms used to control the flow of media in pipelines. They are widely used in modern industry. For most valves, their sealing performance is an important consideration during design and manufacturing. If the sealing performance is poor and media leakage occurs, it will affect the operation and pollute the environment. If toxic or harmful media leaks, it may cause major safety accidents.

[0003] Traditional steel and cast iron plug valves are usually coated with phenolic or other plastic protective layers when used with corrosive media. However, due to the softness, poor wear resistance and short lifespan of these materials, their applications are limited. Ceramic materials have the characteristics of high hardness, strong wear resistance and good corrosion resistance. Therefore, the development of ceramic sealing valve cores has become a current research hotspot.

[0004] Current research has explored incorporating graphene into valve core ceramic materials to improve mechanical and wear resistance while maintaining other ceramic properties. However, due to its structural characteristics, graphene exhibits strong intermolecular forces, making it difficult to uniformly integrate with ceramic materials. Consequently, the superior properties of graphene are not fully realized, limiting its application in valve core ceramic materials. Summary of the Invention

[0005] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes an alumina-based valve core ceramic material and its preparation method.

[0006] The technical solution adopted is as follows:

[0007] An alumina-based valve core ceramic material, comprising the following components by weight:

[0008] Alumina 80-100 parts, zirconium oxide 15-30 parts, boron-doped graphene 4-8 parts, sintering aid 1-5 parts.

[0009] Furthermore, the preparation method of the boron-doped graphene is as follows:

[0010] Graphene and boric acid are added to ethanol and mixed well. The mixture is heated to remove the ethanol. The resulting mixture is then thoroughly ground and transferred to a tube furnace for heat treatment. After that, it is naturally cooled to room temperature, washed with deionized water, and dried.

[0011] Furthermore, the weight ratio of graphene to boric acid is 1-5:1.

[0012] Furthermore, the heat treatment temperature is 900-1000℃, and the heat treatment time is 1-3h.

[0013] Furthermore, the heat treatment is carried out under the protection of an inert gas.

[0014] Furthermore, the sintering aids include magnesium fluoride, nano-silica, and rare earth oxides.

[0015] Furthermore, the weight ratio of the magnesium fluoride, nano-silica, and rare earth oxides is 1-5:1-5:1-5.

[0016] Furthermore, the rare earth oxide is any one or more combinations of samarium oxide, erbium oxide, ytterbium oxide, and lutetium oxide.

[0017] This invention also provides a method for preparing an alumina-based valve core ceramic material:

[0018] Alumina, zirconium oxide, boron-doped graphene, and sintering aids are mixed, ball-milled, and dried. A binder is added, the mixture is granulated, and then pressed into shape. The resulting green body is heated to 1500-1600℃ and sintered for 2-4 hours, then cooled to room temperature in the furnace.

[0019] Furthermore, the heating rate is 5-20℃ / min.

[0020] The beneficial effects of this invention are:

[0021] This invention provides an alumina-based valve core ceramic material. Boron doping can replace carbon atoms at the edges or defect sites of graphene, changing the lattice structure of the graphene framework and increasing the degree of surface defects. This allows for better mixing with alumina and other ceramic materials through ball milling, resulting in a reinforcing effect. During sintering, borides such as zirconium boride can also be generated. Through the pinning and bridging effects of borides, crack propagation can be effectively hindered under external force, improving fracture toughness. Magnesium fluoride can react with alumina to form magnesium aluminum spinel, promoting the transformation of alumina into a plate-like structure and promoting the densification of the ceramic sample. Nano-silica and rare earth oxides can generate a liquid phase at lower temperatures, accelerating the elimination of pores in the ceramic sample, inhibiting excessive growth of alumina grains, promoting grain refinement, and improving mechanical properties. After testing, the ceramic material prepared by this invention exhibits excellent properties and can meet the performance requirements of valve core materials. Attached Figure Description

[0022] Figure 1 This is a cross-sectional morphology diagram of the alumina-based valve core ceramic material prepared in Example 1. Detailed Implementation

[0023] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0024] Example 1:

[0025] An alumina-based valve core ceramic material, comprising the following components by weight:

[0026] 90 parts alumina, 25 parts zirconium oxide, 6 parts boron-doped graphene, 2 parts magnesium fluoride, 1 part nano-silica, and 1 part ytterbium oxide.

[0027] The preparation method of boron-doped graphene is as follows:

[0028] Graphene and boric acid in a weight ratio of 2:1 were added to an appropriate amount of ethanol and stirred until well mixed. The mixture was heated to 80°C while stirring to remove the ethanol. The resulting mixture was then thoroughly ground and transferred to a tube furnace. Under argon protection, the temperature was increased to 950°C at a rate of 10°C / min for 2 hours. After that, it was naturally cooled to room temperature, thoroughly washed with deionized water, and then dried in an oven at 60°C for 10 hours.

[0029] The preparation method of the above-mentioned alumina-based valve core ceramic material:

[0030] Alumina, zirconium oxide, boron-doped graphene, magnesium fluoride, nano-silica, and ytterbium oxide were added to a planetary ball mill and mixed with ethanol as the milling medium. After milling for 10 hours, the mixture was dried and then granulated with 10% polyvinyl alcohol as a binder. The granules were then passed through a 200-mesh sieve and placed into a mold. The mixture was then pressed into shape by isostatic pressing at 150 MPa. The resulting green body was heated to 1550 °C at a rate of 5 °C / min and sintered for 2 hours. After sintering, the green body was cooled to room temperature in the furnace.

[0031] Example 2:

[0032] An alumina-based valve core ceramic material, comprising the following components by weight:

[0033] 100 parts alumina, 30 parts zirconium oxide, 8 parts boron-doped graphene, 2 parts magnesium fluoride, 1 part nano-silica, and 1 part ytterbium oxide.

[0034] The preparation method of boron-doped graphene is as follows:

[0035] Graphene and boric acid in a weight ratio of 2:1 were added to an appropriate amount of ethanol and stirred until well mixed. The mixture was heated to 80°C while stirring to remove the ethanol. The resulting mixture was then thoroughly ground and transferred to a tube furnace. Under argon protection, the temperature was increased to 950°C at a rate of 10°C / min for 2 hours. After that, it was naturally cooled to room temperature, thoroughly washed with deionized water, and then dried in an oven at 60°C for 10 hours.

[0036] The preparation method of the above-mentioned alumina-based valve core ceramic material:

[0037] Alumina, zirconium oxide, boron-doped graphene, magnesium fluoride, nano-silica, and ytterbium oxide were added to a planetary ball mill and mixed with ethanol as the milling medium. After milling for 10 hours, the mixture was dried and then granulated with 10% polyvinyl alcohol as a binder. The granules were then passed through a 200-mesh sieve and placed into a mold. The mixture was then pressed into shape by isostatic pressing at 150 MPa. The resulting green body was heated to 1550 °C at a rate of 5 °C / min and sintered for 2 hours. After sintering, the green body was cooled to room temperature in the furnace.

[0038] Example 3:

[0039] An alumina-based valve core ceramic material, comprising the following components by weight:

[0040] 80 parts alumina, 15 parts zirconium oxide, 4 parts boron-doped graphene, 2 parts magnesium fluoride, 1 part nano-silica, and 1 part ytterbium oxide.

[0041] The preparation method of boron-doped graphene is as follows:

[0042] Graphene and boric acid in a weight ratio of 2:1 were added to an appropriate amount of ethanol and stirred until well mixed. The mixture was heated to 80°C while stirring to remove the ethanol. The resulting mixture was then thoroughly ground and transferred to a tube furnace. Under argon protection, the temperature was increased to 950°C at a rate of 10°C / min for 2 hours. After that, it was naturally cooled to room temperature, thoroughly washed with deionized water, and then dried in an oven at 60°C for 10 hours.

[0043] The preparation method of the above-mentioned alumina-based valve core ceramic material:

[0044] Alumina, zirconium oxide, boron-doped graphene, magnesium fluoride, nano-silica, and ytterbium oxide were added to a planetary ball mill and mixed with ethanol as the milling medium. After milling for 10 hours, the mixture was dried and then granulated with 10% polyvinyl alcohol as a binder. The granules were then passed through a 200-mesh sieve and placed into a mold. The mixture was then pressed into shape by isostatic pressing at 150 MPa. The resulting green body was heated to 1550 °C at a rate of 5 °C / min and sintered for 2 hours. After sintering, the green body was cooled to room temperature in the furnace.

[0045] Example 4:

[0046] It is basically the same as Example 1, except that samarium oxide is used instead of ytterbium oxide.

[0047] Example 5:

[0048] It is basically the same as Example 1, except that erbium oxide is used instead of ytterbium oxide.

[0049] Comparative Example 1:

[0050] It is basically the same as Example 1, except that boron-doped graphene is not added.

[0051] Comparative Example 2:

[0052] It is basically the same as Example 1, except that graphene is used instead of boron-doped graphene.

[0053] Comparative Example 3:

[0054] It is basically the same as Example 1, except that magnesium fluoride is not added.

[0055] Comparative Example 4:

[0056] It is basically the same as Example 1, except that no nano-silica is added.

[0057] Comparative Example 5:

[0058] It is basically the same as Example 1, except that ytterbium oxide is not added.

[0059] Performance testing:

[0060] The alumina-based valve core ceramic materials prepared in Examples 1-5 and Comparative Examples 1-5 of the present invention were used as samples for performance testing.

[0061] ① The Rockwell hardness of each sample was tested using a Rockwell hardness tester;

[0062] ② The bending strength of the specimens was tested using the three-point bending method. The specimen size was 3mm×4mm×36mm. Each group of specimens was tested 5 times and the average value was taken.

[0063] ③ The fracture toughness values ​​of each specimen were tested according to GB / T23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single-sided Precracked Beam (SEPB) Method";

[0064] ④ Weigh out the sample mass M, place it in an alumina ceramic jar, and add water at a ratio of sample to water of 2:1. Grind the sample on a planetary ball mill at a speed of 100 r / min for 8 hours. Then stop grinding, remove the sample, clean it, and dry it in an oven until constant weight. Weigh out the mass m. The wear rate is shown in the following formula:

[0065]

[0066] The test results are shown in Table 1 below:

[0067] Table 1:

[0068]

[0069] As shown in Table 1 above, the ceramic material prepared by this invention has good properties and can meet the performance requirements of valve core materials.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An alumina-based valve core ceramic material, characterized in that, By weight, it comprises the following components: Alumina 80-100 parts, zirconium oxide 15-30 parts, boron-doped graphene 4-8 parts, sintering aid 1-5 parts; The preparation method of the boron-doped graphene is as follows: Graphene and boric acid were added to ethanol and mixed well. The mixture was heated to remove the ethanol. The resulting mixture was then thoroughly ground and transferred to a tube furnace for heat treatment. After that, it was naturally cooled to room temperature, washed with deionized water, and dried. The heat treatment temperature is 900-1000℃, and the heat treatment time is 1-3 hours. The sintering aids include magnesium fluoride, nano-silica, and rare earth oxides.

2. The alumina-based valve core ceramic material as described in claim 1, characterized in that, The weight ratio of graphene to boric acid is 1-5:

1.

3. The alumina-based valve core ceramic material as described in claim 1, characterized in that, The heat treatment was carried out under inert gas protection.

4. The alumina-based valve core ceramic material as described in claim 1, characterized in that, The weight ratio of magnesium fluoride, nano-silica, and rare earth oxides is 1-5:1-5:1-5.

5. The alumina-based valve core ceramic material as described in claim 4, characterized in that, The rare earth oxide is any one or more combinations of samarium oxide, erbium oxide, ytterbium oxide, and lutetium oxide.

6. A method for preparing an alumina-based valve core ceramic material as described in any one of claims 1-5, characterized in that, Alumina, zirconium oxide, boron-doped graphene, and sintering aids are mixed, ball-milled, and dried. A binder is added, the mixture is granulated, and then pressed into shape. The resulting green body is heated to 1500-1600℃ and sintered for 2-4 hours, then cooled to room temperature in the furnace.

7. The method for preparing the alumina-based valve core ceramic material as described in claim 6, characterized in that, The heating rate is 5-20℃ / min.

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