Preparation method of equiaxial self-expanding ceramic and product thereof

Abstract

Aluminum oxide powder, graphene oxide powder, magnesium oxide powder and manganese oxide powder are used as main raw materials, a simple and convenient compression molding process is combined, proper heat treatment is performed, and the novel high-performance equiaxed self-expanding ceramic product with high volume expansion rate and high compressive strength is prepared. The method has the advantages of simple and convenient process, low cost, easiness in industrialization, excellent product performance and the like, and has wide application prospects in the fields of engineering, scientific research and the like.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a preparation method of equiaxed self-expanding ceramics and a product thereof. Background Art

[0002] Isometric self-expanding materials are a type of special material that can expand spontaneously and evenly in all directions (with the same expansion rate) under specific conditions (such as temperature changes, humidity changes or chemical reactions, etc.). They usually achieve the characteristics of isometric self-expanding through phase change expansion, chemical reaction expansion or thermal expansion. Compared with traditional expansion materials (or foaming materials) with complex preparation processes and non-uniform expansion rates in all directions, this material has significant technical and performance advantages. At the same time, isometric self-expanding materials have many unique performance advantages, such as being able to ensure that no stress concentration occurs inside the material during the expansion process (will not cause cracks or damage to the product, etc.), and being able to precisely control the volume stability of the product by regulating the expansion rate, so that it has a wide and important application prospect in engineering and scientific research, especially in the fields of precision instruments, aerospace, structural engineering and biomedicine.

[0003] At present, although equiaxed self-expanding materials have shown great application potential in many important fields, the types of materials that can produce equiaxed self-expanding effects are relatively few and their performance needs to be improved, especially the relative scarcity of equiaxed self-expanding ceramic materials, which limits their application and development. Therefore, it is of great significance to carry out innovations in raw material composition design and preparation technology, and to develop high-performance equiaxed self-expanding ceramic products with controllable expansion rate and high mechanical strength to promote the technological progress of such materials and broaden their applications. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing equiaxed self-expanding ceramics, using aluminum oxide powder, graphene oxide powder, magnesium oxide powder and manganese oxide powder as main raw materials, and combining a simple pressing molding process, and heat treatment, combining chemical reaction expansion and thermal expansion mechanisms to prepare a new type of high-performance equiaxed self-expanding ceramic product. Another purpose of the present invention is to provide a product obtained by using the above-mentioned method for preparing equiaxed self-expanding ceramics.

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

[0006] The present invention provides a method for preparing an equiaxed self-expanding ceramic, comprising the following steps:

[0007] (1) Alumina powder, graphene oxide powder, magnesium oxide powder, and manganese oxide powder are used as base materials, polyvinyl alcohol solution is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 10-60wt% of aluminum oxide powder, 1-5wt% of graphene oxide powder, 5-10wt% of magnesium oxide powder, and 30-80wt% of manganese oxide powder, and the amount of the polyvinyl alcohol solution and ethanol is 10-20wt% and 5-10wt% of the base material, respectively;

[0008] (2) using a compression molding process to compress the mixed material into a green body;

[0009] (3) The green body is heat treated, i.e., dried at 60-100° C. for 2-4 hours; and then sintered at 1100-1250° C. for 1-2 hours to obtain an equiaxed self-expanding ceramic product.

[0010] In the above scheme, the average particle size of the aluminum oxide powder of the present invention is 500nm~5μm, the average particle size of the graphene oxide powder is 50~200nm, the average particle size of the magnesium oxide powder is 100~300nm, and the average particle size of the manganese oxide powder is 500nm~15μm.

[0011] Furthermore, the step (2) of the present invention is pressed and formed at a pressure of 8-12 MPa. The manganese oxide is manganous oxide, manganese tetraoxide, manganese trioxide, or manganese dioxide. The concentration of the polyvinyl alcohol solution is 5-10%.

[0012] The product prepared by the preparation method of the equiaxed self-expanding ceramics of the present invention has a volume expansion rate of 50-90% and a compressive strength of 5-12 MPa.

[0013] The present invention has the following beneficial effects:

[0014] The present invention aims at the key problems that need to be solved urgently, such as the relatively small number of equiaxed self-expanding materials and the need to improve their performance, especially the relative scarcity of equiaxed self-expanding ceramic materials. First, based on the pyrolysis and thermal expansion behavior of graphene oxide and manganese oxide, a basis is provided for the equiaxed self-expanding of ceramic materials; at the same time, combined with the solid-phase synthesis reaction mechanism of aluminum oxide, magnesium oxide and manganese oxide, while achieving thermally induced phase change expansion, the ceramic product is also endowed with higher mechanical strength characteristics. Therefore, the present invention proposes to use aluminum oxide powder, graphene oxide powder, magnesium oxide powder and manganese oxide powder as the main raw materials, and at the same time combine a simple pressing molding process, and after heat treatment, based on the mechanism of chemical reaction expansion and thermal expansion, a new high-performance equiaxed self-expanding ceramic product with high volume expansion rate and high compressive strength is prepared. The present invention has many advantages such as simple process, low cost, easy industrialization, excellent performance, etc., and has leading technical competitiveness and broad market space in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings:

[0016] Figure 1 This is a physical comparison diagram of the equiaxed self-expanding ceramic prepared in an embodiment of the present invention before and after sintering;

[0017] Figure 2 It is a comparison diagram of the microstructure of the equiaxed self-expanding ceramic prepared in the embodiment of the present invention before and after sintering. DETAILED DESCRIPTION

[0018] Embodiment 1:

[0019] This embodiment provides a method for preparing an equiaxed self-expanding ceramic, and the steps are as follows:

[0020] (1) Alumina powder (average particle size of 5 μm), graphene oxide powder (average particle size of 200 nm), magnesium oxide powder (average particle size of 300 nm), and manganese dioxide powder (average particle size of 500 nm) are used as base materials, a polyvinyl alcohol solution with a concentration of 5 wt% is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 60 wt% of aluminum oxide powder, 1 wt% of graphene oxide powder, 5 wt% of magnesium oxide powder, and 34 wt% of manganese dioxide powder, and the amounts of polyvinyl alcohol solution and ethanol are 15 wt% and 8 wt% of the base material, respectively;

[0021] (2) using a compression molding process to compress the mixed material under a pressure of 12 MPa to obtain a green body;

[0022] (3) The green body is heat treated by drying it in an oven at 60°C for 4 hours; and then sintering it in a muffle furnace at 1200°C for 1.5 hours to obtain an equiaxed self-expanding ceramic product with a volume expansion rate of 75.29% and a compressive strength of 10.61 MPa.

[0023] Embodiment 2:

[0024] This embodiment provides a method for preparing an equiaxed self-expanding ceramic, and the steps are as follows:

[0025] (1) Alumina powder (average particle size of 500 nm), graphene oxide powder (average particle size of 100 nm), magnesium oxide powder (average particle size of 200 nm), and manganese trioxide powder (average particle size of 5 μm) are used as base materials, a polyvinyl alcohol solution with a concentration of 10 wt% is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 20 wt% of aluminum oxide powder, 5 wt% of graphene oxide powder, 10 wt% of magnesium oxide powder, and 65 wt% of manganese trioxide powder, and the amounts of polyvinyl alcohol solution and ethanol are 10 wt% and 9 wt% of the base material, respectively;

[0026] (2) using a compression molding process to compress the mixed material under a pressure of 10 MPa to obtain a green body;

[0027] (3) The green body is heat treated by drying it in an oven at 80°C for 3 hours; and then sintering it in a muffle furnace at 1100°C for 2 hours to obtain an equiaxed self-expanding ceramic product with a volume expansion rate of 80.12% and a compressive strength of 8.56 MPa.

[0028] Embodiment three:

[0029] This embodiment provides a method for preparing an equiaxed self-expanding ceramic, and the steps are as follows:

[0030] (1) Alumina powder (average particle size of 1 μm), graphene oxide powder (average particle size of 50 nm), magnesium oxide powder (average particle size of 100 nm), and manganous oxide powder (average particle size of 1 μm) are used as base materials, a polyvinyl alcohol solution with a concentration of 5 wt% is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 10 wt% of aluminum oxide powder, 3 wt% of graphene oxide powder, 7 wt% of magnesium oxide powder, and 80 wt% of manganous oxide powder, and the amounts of polyvinyl alcohol solution and ethanol are 20 wt% and 5 wt% of the base material, respectively;

[0031] (2) using a compression molding process to compress the mixed material under a pressure of 8 MPa to obtain a green body;

[0032] (3) The green body is heat treated by drying it in an oven at 60°C for 4 hours; and then sintering it in a muffle furnace at 1100°C for 2 hours to obtain an equiaxed self-expanding ceramic product with a volume expansion rate of 90.03% and a compressive strength of 5.32 MPa.

[0033] Embodiment 4:

[0034] This embodiment provides a method for preparing an equiaxed self-expanding ceramic, and the steps are as follows:

[0035] (1) Alumina powder (average particle size of 3 μm), graphene oxide powder (average particle size of 200 nm), magnesium oxide powder (average particle size of 100 nm), and manganese tetraoxide powder (average particle size of 15 μm) are used as base materials, a polyvinyl alcohol solution with a concentration of 10 wt% is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 58 wt% of alumina powder, 4 wt% of graphene oxide powder, 8 wt% of magnesium oxide powder, and 30 wt% of manganese tetraoxide powder, and the amounts of polyvinyl alcohol solution and ethanol are 10 wt% and 10 wt% of the base material, respectively;

[0036] (2) using a compression molding process to compress the mixed material under a pressure of 10 MPa to obtain a green body;

[0037] (3) The green body is heat treated, i.e., placed in an oven for drying at 100°C for 2 hours; and then placed in a muffle furnace for sintering at 1250°C for 1 hour to obtain an equiaxed self-expanding ceramic. Compared with the green body before sintering, the equiaxed self-expanding ceramic after sintering has a relatively uniform and large number of pore structures inside. Its volume expansion rate is 50.12% and its compressive strength is 12.38MPa.

[0038] like Figure 1 As shown, in the preparation method of the embodiment of the present invention, after the sintering treatment, the green body undergoes obvious equiaxed volume expansion in three dimensions. Figure 2 As shown, compared with the green body before firing, the fired equiaxed self-expanding ceramic product has a uniform and abundant pore structure inside.

Claims

1. A method for preparing equiaxed self-expanding ceramics, characterized in that The following steps are involved: (1) Alumina powder, graphene oxide powder, magnesium oxide powder, and manganese oxide powder are used as base materials, polyvinyl alcohol solution is used as a molding agent, and ethanol is used as a dispersant, and the mixture is mixed and aged to obtain a mixed material; wherein the raw material composition of the base material is 10-60wt% of aluminum oxide powder, 1-5wt% of graphene oxide powder, 5-10wt% of magnesium oxide powder, and 30-80wt% of manganese oxide powder, and the amount of the polyvinyl alcohol solution and ethanol is 10-20wt% and 5-10wt% of the base material, respectively; (2) using a compression molding process to compress the mixed material into a green body; (3) The green body is heat treated, i.e., dried at 60-100° C. for 2-4 hours; and then sintered at 1100-1250° C. for 1-2 hours to obtain an equiaxed self-expanding ceramic product.

2. The method for preparing equiaxed self-expanding ceramics according to claim 1, characterized in that: The average particle size of the aluminum oxide powder is 500nm-5μm, the average particle size of the graphene oxide powder is 50-200nm, the average particle size of the magnesium oxide powder is 100-300nm, and the average particle size of the manganese oxide powder is 500nm-15μm.

3. The method for preparing equiaxed self-expanding ceramics according to claim 1, characterized in that: The step (2) is performed by compression molding at a pressure of 8 to 12 MPa.

4. The method for preparing equiaxed self-expanding ceramics according to claim 1, characterized in that: The manganese oxide is manganous oxide, trimanganese tetraoxide, dimanganese trioxide, or manganese dioxide.

5. The method for preparing equiaxed self-expanding ceramics according to claim 1, characterized in that: The concentration of the polyvinyl alcohol solution is 5-10%.

6. A product obtained by the method for preparing equiaxed self-expanding ceramics according to any one of claims 1 to 5.

7. The product according to claim 6, characterized in that: The product prepared by the preparation method of the equiaxed self-expanding ceramic has a volume expansion rate of 50-90% and a compressive strength of 5-12 MPa.

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