Gradient porous ceramic preform, aluminum alloy toughened ceramic composite material and preparation
阅读说明：本技术 梯度多孔陶瓷预制体、铝合金增韧陶瓷复合材料及制备 (Gradient porous ceramic preform, aluminum alloy toughened ceramic composite material and preparation ) 是由 贠柯 鲁元 王若虹 张建龙 刘金娥 毕成 杨旭 于 2021-09-14 设计创作，主要内容包括：本发明公开了一种梯度多孔陶瓷预制体、铝合金增韧陶瓷复合材料及制备。该梯度多孔陶瓷预制体包括依次设置的第一多孔陶瓷预制体层、第二多孔陶瓷预制体层、第三多孔陶瓷预制体层、第四多孔陶瓷预制体层和第五多孔陶瓷预制体层；所述第一多孔陶瓷预制体层的气孔率、第二多孔陶瓷预制体层的气孔率、第三多孔陶瓷预制体层的气孔率、第四多孔陶瓷预制体层的气孔率和第五多孔陶瓷预制体层的气孔率依次增大。本发明的梯度多孔陶瓷预制体通过五层叠设的结构,具有良好的耐蚀性、高比模量、高比强度和高耐磨性,同时在高温环境下能表现出良好的性能,符合安全钳楔块的性能需求,在电梯安全钳楔块制造领域具有广阔的应用前景。(The invention discloses a gradient porous ceramic preform, an aluminum alloy toughened ceramic composite material and preparation. The gradient porous ceramic preform comprises a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer and a fifth porous ceramic preform layer which are arranged in sequence; and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence. The gradient porous ceramic preform has a five-layer laminated structure, has good corrosion resistance, high specific modulus, high specific strength and high wear resistance, can show good performance in a high-temperature environment, meets the performance requirements of safety tongs wedge blocks, and has wide application prospects in the field of manufacturing of elevator safety tongs wedge blocks.)
1. The gradient porous ceramic preform is characterized by comprising a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer and a fifth porous ceramic preform layer which are sequentially arranged;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
2. The gradient porous ceramic preform of claim 1, wherein the thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer, and the thickness of the fifth porous ceramic preform layer are each 10mm to 20 mm.
3. The gradient porous ceramic preform of claim 1, wherein the raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer, and the fifth porous ceramic preform layer each comprise boron oxide, graphene, lutetium oxide, and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 50-56%, the mass percentage of graphene is 34-40%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 51-57%, the mass percentage of graphene is 35-41%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage content of boron oxide is 52-58%, the mass percentage content of graphene is 36-42%, the mass percentage content of lutetium oxide is 3%, and the mass percentage content of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage content of boron oxide is 53-59%, the mass percentage content of graphene is 37-43%, the mass percentage content of lutetium oxide is 2%, and the mass percentage content of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 54-60%, the mass percentage of graphene is 38-44%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
4. A method for preparing the gradient porous ceramic preform according to claim 1, comprising sequentially placing the respective mixed raw materials in a mold in the order of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer, and performing compression molding and vacuum sintering to obtain the gradient porous ceramic preform.
5. The method according to claim 4, comprising in particular:
step one, respectively carrying out wet ball milling drying on a raw material of a first porous ceramic prefabricated body layer, a raw material of a second porous ceramic prefabricated body layer, a raw material of a third porous ceramic prefabricated body layer, a raw material of a fourth porous ceramic prefabricated body layer and a raw material of a fifth porous ceramic prefabricated body layer to obtain mixed raw materials correspondingly;
step two, sequentially placing the mixed raw material of the first porous ceramic prefabricated body layer, the mixed raw material of the second porous ceramic prefabricated body layer, the mixed raw material of the third porous ceramic prefabricated body layer, the mixed raw material of the fourth porous ceramic prefabricated body layer and the mixed raw material of the fifth porous ceramic prefabricated body layer in a mold, pressurizing to 100 kN-120 kN, keeping for 2 min-4 min, and releasing the pressure to obtain a green body; the thickness of each layer of mixed raw materials laid in the mould is 15 mm-25 mm;
step three, under the vacuum environment, raising the temperature of the green body to 1800-2000 ℃ according to the heating rate of 20-40 ℃/min, and keeping the temperature for 4-6 h for sintering;
and step four, cooling the sintered blank along with the furnace to obtain the gradient porous ceramic prefabricated body.
6. The method according to claim 5, wherein the vacuum degree of the vacuum environment in the third step is 400Pa to 500 Pa; and step three, applying a pressure of 80-100 kN to the green body in the sintering process.
7. An aluminum alloy toughened ceramic composite material, comprising an aluminum alloy and the gradient porous ceramic preform of any one of claims 1 to 8, wherein the aluminum alloy is ZL101 aluminum alloy or ZL102 aluminum alloy.
8. A method of making an aluminum alloy toughened ceramic composite as claimed in claim 7 comprising:
step one, coating a release agent in a pressure chamber of a die casting machine;
secondly, placing the gradient porous ceramic preform in a pressure chamber, and preheating the pressure chamber to 500-700 ℃;
step three, pouring molten aluminum alloy liquid into the pressure chamber;
step four, vacuumizing the pressure chamber to less than 200Pa, applying pressure to the pressure chamber filled with the molten aluminum alloy liquid and the gradient porous ceramic prefabricated body to 40-60 MPa, keeping for 10-20 minutes, and stopping applying pressure;
step five, cooling, demolding to obtain an ingot, re-melting the ingot, and taking out;
and sixthly, performing heat treatment on the re-melted material to obtain the aluminum alloy toughened ceramic composite material for the elevator safety tongs wedge block.
9. The method of claim 8, wherein step six of said heat treating comprises: and putting the re-melted material into a muffle furnace, heating the furnace temperature to 500-700 ℃ from the room temperature within 0.6-1 h, preserving the temperature for 5-7 h, taking out, quenching with water, and preserving the temperature for 4-8 h at 160-200 ℃.
Technical Field
The invention belongs to the technical field of material forming, and particularly relates to a gradient porous ceramic preform, an aluminum alloy toughened ceramic composite material and preparation.
Background
The application of the elevator in modern life is increasingly common, along with the increasing of high-rise buildings and the continuous progress of high-performance elevator development, the running speed of the elevator is faster and faster, and the highest running speed of the elevator in the world is 17m/s at present. However, with the recent occurrence of many elevator accidents, the safety and reliability of elevators are receiving great attention. When the elevator accidentally drops due to a fault, the speed of the elevator exceeds a limit value, so that the speed limiter acts, and the elevator is braked under the braking action of the safety tongs, thereby ensuring the personal safety. The safety tongs are extremely important for guaranteeing the daily safe operation of the elevator. However, under high-speed and high-load service conditions, the friction process between the elevator safety gear brake block and the guide rail is often accompanied by significant changes of temperature and pressure, which puts severe requirements on the comprehensive mechanical property, thermal property, frictional wear property and stability of various performance parameters of the safety gear brake block in the service process. If the performance or service stability of the safety tongs brake block cannot meet the design service requirement, the elevator is prone to potential safety accidents such as brake failure and sudden stop and braking. The traditional friction braking material (gray cast iron) is often subjected to excessive wear under the action of frictional heat, the friction coefficient is reduced, and the safety requirement of the modern high-performance elevator cannot be met.
The safety gear wedge block produced by the traditional steel material is easy to corrode under the condition of long-term non-work, needs surface galvanization, has low friction coefficient with a guide rail, needs surface knurling and brings inconvenience to production and application. The elevator safety tongs wedge block material is convenient and easy to obtain, and can meet the safety requirement of the modern high-performance elevator, and the key for solving the problems is provided.
Disclosure of Invention
The invention aims to solve the technical problem of providing a gradient porous ceramic preform, an aluminum alloy toughened ceramic composite material and preparation thereof aiming at the defects of the prior art. The gradient porous ceramic preform and the aluminum alloy toughened ceramic composite material based on the gradient porous ceramic preform have a five-layer laminated structure, have good corrosion resistance, high specific modulus, high specific strength and high wear resistance, can show good performance in a high-temperature environment, meet the performance requirements of safety tongs wedge blocks, and have wide application prospects in the field of manufacturing of elevator safety tongs wedge blocks.
In order to solve the technical problems, the invention adopts the technical scheme that: the gradient porous ceramic preform is characterized by comprising a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer and a fifth porous ceramic preform layer which are sequentially arranged;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
The gradient porous ceramic preform is characterized in that the thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer and the thickness of the fifth porous ceramic preform layer are all 10-20 mm.
The gradient porous ceramic preform is characterized in that the raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer respectively comprise boron oxide, graphene, lutetium oxide and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 50-56%, the mass percentage of graphene is 34-40%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 51-57%, the mass percentage of graphene is 35-41%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage content of boron oxide is 52-58%, the mass percentage content of graphene is 36-42%, the mass percentage content of lutetium oxide is 3%, and the mass percentage content of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage content of boron oxide is 53-59%, the mass percentage content of graphene is 37-43%, the mass percentage content of lutetium oxide is 2%, and the mass percentage content of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 54-60%, the mass percentage of graphene is 38-44%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
In addition, the invention also provides a method for preparing the gradient porous ceramic preform, which is characterized by comprising the steps of sequentially placing the correspondingly mixed raw materials in a mold according to the sequence of a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer and a fifth porous ceramic preform layer, and carrying out compression molding and vacuum sintering to obtain the gradient porous ceramic preform.
The method is characterized by specifically comprising the following steps:
step one, respectively carrying out wet ball milling drying on a raw material of a first porous ceramic prefabricated body layer, a raw material of a second porous ceramic prefabricated body layer, a raw material of a third porous ceramic prefabricated body layer, a raw material of a fourth porous ceramic prefabricated body layer and a raw material of a fifth porous ceramic prefabricated body layer to obtain mixed raw materials correspondingly;
step two, sequentially placing the mixed raw material of the first porous ceramic prefabricated body layer, the mixed raw material of the second porous ceramic prefabricated body layer, the mixed raw material of the third porous ceramic prefabricated body layer, the mixed raw material of the fourth porous ceramic prefabricated body layer and the mixed raw material of the fifth porous ceramic prefabricated body layer in a mold, pressurizing to 100 kN-120 kN, keeping for 2 min-4 min, and releasing the pressure to obtain a green body; the thickness of each layer of mixed raw materials laid in the mould is 15 mm-25 mm;
step three, under the vacuum environment, raising the temperature of the green body to 1800-2000 ℃ according to the heating rate of 20-40 ℃/min, and keeping the temperature for 4-6 h for sintering;
and step four, cooling the sintered blank along with the furnace to obtain the gradient porous ceramic prefabricated body.
The method is characterized in that the vacuum degree of the vacuum environment in the step three is 400 Pa-500 Pa; and step three, applying a pressure of 80-100 kN to the green body in the sintering process.
The invention further provides an aluminum alloy toughened ceramic composite material, which is characterized by comprising an aluminum alloy and the gradient porous ceramic preform as claimed in any one of claims 1 to 8, wherein the aluminum alloy is ZL101 aluminum alloy or ZL102 aluminum alloy.
Furthermore, the invention also provides a method for preparing the aluminum alloy toughened ceramic composite material, which is characterized by comprising the following steps:
step one, coating a release agent in a pressure chamber of a die casting machine;
secondly, placing the gradient porous ceramic preform in a pressure chamber, and preheating the pressure chamber to 500-700 ℃;
step three, pouring molten aluminum alloy liquid into the pressure chamber;
step four, vacuumizing the pressure chamber to less than 200Pa, applying pressure to the pressure chamber filled with the molten aluminum alloy liquid and the gradient porous ceramic prefabricated body to 40-60 MPa, keeping for 10-20 minutes, and stopping applying pressure;
step five, cooling, demolding to obtain an ingot, re-melting the ingot, and taking out;
and sixthly, performing heat treatment on the re-melted material to obtain the aluminum alloy toughened ceramic composite material for the elevator safety tongs wedge block.
The method as described above, characterized in that the heat treatment comprises: and putting the re-melted material into a muffle furnace, heating the furnace temperature to 500-700 ℃ from the room temperature within 0.6-1 h, preserving the temperature for 5-7 h, taking out, quenching with water, and preserving the temperature for 4-8 h at 160-200 ℃.
Compared with the prior art, the invention has the following advantages:
1. the invention utilizes the specific layered structure of the ceramic prefabricated layer and the gradient-changing porosity to endow the material with wear resistance and impact resistance, has good corrosion resistance, high specific modulus, high specific strength and high wear resistance, meets the performance requirements of the safety gear wedge block, and has wide application prospect in the field of manufacturing of elevator safety gear wedge blocks.
2. The raw materials of the gradient porous ceramic preform comprise boron oxide, graphene, lutetium oxide and aluminum oxide, and the boron carbide ceramic preform is obtained through vacuum sintering and has good wear resistance and impact resistance.
3. The method for preparing the gradient porous ceramic preform comprises the steps of mixing boron oxide, graphene, lutetium oxide and aluminum oxide with specific particle size ranges according to a specific proportion, laying, compression molding and vacuum sintering to obtain the gradient porous ceramic preform, the defects that the traditional ceramic material is easy to agglomerate and the particle size is not uniform can be effectively overcome, the physical characteristics of the boron oxide, the graphene, the lutetium oxide and the aluminum oxide are fully utilized, and high-purity boron carbide ceramic with uniform and fine particle sizes is obtained and has higher hardness and wear resistance.
4. The aluminum alloy toughening ceramic composite material comprises an aluminum alloy and the gradient porous ceramic prefabricated body, and the physical properties of the aluminum alloy and the gradient porous ceramic prefabricated body are fully combined, so that the properties of the traditional steel material are improved.
5. The method for preparing the aluminum alloy toughened ceramic composite material has the advantages that the material with gradient change in hardness and toughness is obtained by extrusion casting of the molten aluminum alloy and the gradient porous ceramic prefabricated body, the density is high, the hardness is reduced layer by layer from the safety gear wedge block working surface which is in mutual friction with the elevator guide rail to the fixing surface where the safety gear wedge block is fixed with the base, the impact toughness is increased layer by layer, the safety gear wedge block working part which is in mutual friction with the elevator guide rail has excellent friction and wear resistance, the safety gear wedge block base part which is fixed with the base has excellent impact resistance, and the performance requirements of the safety gear wedge block are met.
6. The method for preparing the aluminum alloy toughened ceramic composite material provided by the invention aims at solving the problem of poor wettability of the molten alloy liquid and the gradient porous ceramic preform, and presses the molten aluminum alloy liquid into the pore channels of the gradient porous ceramic preform by a vacuum extrusion casting and pressing method, so that the method has the characteristic of infiltration time, and the molten aluminum alloy liquid is higher in filling amount and higher in physical property.
7. The preparation method has reasonable process, simple operation and wide application value.
The technical solution of the present invention is further described in detail with reference to the accompanying drawings and embodiments.
Drawings
Fig. 1 is a schematic structural view of an aluminum alloy toughened ceramic composite of example 4.
FIG. 2 is a scanning electron microscope image of the aluminum alloy toughened ceramic composite of example 4.
Detailed Description
The invention provides a gradient porous ceramic prefabricated body which comprises a first porous ceramic prefabricated body layer, a second porous ceramic prefabricated body layer, a third porous ceramic prefabricated body layer, a fourth porous ceramic prefabricated body layer and a fifth porous ceramic prefabricated body layer which are sequentially arranged;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
Further, the thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer and the thickness of the fifth porous ceramic preform layer are all 10mm to 20 mm.
Further, the raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer all comprise boron oxide, graphene, lutetium oxide and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 50-56%, the mass percentage of graphene is 34-40%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 51-57%, the mass percentage of graphene is 35-41%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage content of boron oxide is 52-58%, the mass percentage content of graphene is 36-42%, the mass percentage content of lutetium oxide is 3%, and the mass percentage content of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage content of boron oxide is 53-59%, the mass percentage content of graphene is 37-43%, the mass percentage content of lutetium oxide is 2%, and the mass percentage content of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 54-60%, the mass percentage of graphene is 38-44%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
In another aspect, the invention further provides an aluminum alloy toughened ceramic composite material, which comprises an aluminum alloy and the gradient porous ceramic preform, wherein the aluminum alloy is ZL101 aluminum alloy or ZL102 aluminum alloy.
The present invention will be described in detail with reference to the following examples, which are not intended to limit the present invention.
A series of gradient porous ceramic preforms and aluminum alloy toughened ceramic composite materials are prepared according to the method disclosed by the invention, and the method is as follows.
Example 1
The present embodiment provides a gradient porous ceramic preform, including a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer, and a fifth porous ceramic preform layer, which are sequentially disposed;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
The thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer and the thickness of the fifth porous ceramic preform layer are all 10 mm.
The raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer respectively comprise boron oxide, graphene, lutetium oxide and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 50%, the mass percentage of graphene is 40%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 51%, the mass percentage of graphene is 41%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage of boron oxide is 52%, the mass percentage of graphene is 42%, the mass percentage of lutetium oxide is 3%, and the mass percentage of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage of boron oxide is 53%, the mass percentage of graphene is 43%, the mass percentage of lutetium oxide is 2%, and the mass percentage of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 54%, the mass percentage of graphene is 44%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
In addition, the present embodiment also provides a method for preparing the gradient porous ceramic preform, including:
step one, respectively carrying out wet ball milling drying on a raw material of a first porous ceramic prefabricated body layer, a raw material of a second porous ceramic prefabricated body layer, a raw material of a third porous ceramic prefabricated body layer, a raw material of a fourth porous ceramic prefabricated body layer and a raw material of a fifth porous ceramic prefabricated body layer to obtain mixed raw materials correspondingly;
step two, sequentially placing the mixed raw material of the first porous ceramic prefabricated body layer, the mixed raw material of the second porous ceramic prefabricated body layer, the mixed raw material of the third porous ceramic prefabricated body layer, the mixed raw material of the fourth porous ceramic prefabricated body layer and the mixed raw material of the fifth porous ceramic prefabricated body layer in a mold, pressurizing to 100kN, keeping for 2min, and relieving the pressure to obtain a green body; the thickness of each layer of mixed raw materials laid in the mould is 15 mm;
step three, under the vacuum environment, heating the green body to 1800 ℃ according to the heating rate of 20 ℃/min, and keeping the temperature for 4 hours for sintering; thirdly, the vacuum degree of the vacuum environment is 400 Pa; step three also comprises applying a pressure of 80kN to the green body during sintering
And step four, cooling the sintered blank along with the furnace to obtain the gradient porous ceramic prefabricated body.
The composition and porosity of the raw material for each layer in the gradient porous ceramic preform of this example are shown in Table 1.
TABLE 1 parameters of the gradient porous ceramic preform of example 1
As can be seen from table 1, the gradient porous ceramic preform of the present example has a single-layer porosity that increases layer by layer.
Example 2
The present embodiment provides a gradient porous ceramic preform, including a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer, and a fifth porous ceramic preform layer, which are sequentially disposed;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
The thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer and the thickness of the fifth porous ceramic preform layer are all 15 mm.
The raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer respectively comprise boron oxide, graphene, lutetium oxide and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 53%, the mass percentage of graphene is 37%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 54%, the mass percentage of graphene is 38%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage of boron oxide is 55%, the mass percentage of graphene is 39%, the mass percentage of lutetium oxide is 3%, and the mass percentage of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage of boron oxide is 56%, the mass percentage of graphene is 40%, the mass percentage of lutetium oxide is 2%, and the mass percentage of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 57%, the mass percentage of graphene is 41%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
In addition, the present embodiment also provides a method for preparing the gradient porous ceramic preform, including:
step one, respectively carrying out wet ball milling drying on a raw material of a first porous ceramic prefabricated body layer, a raw material of a second porous ceramic prefabricated body layer, a raw material of a third porous ceramic prefabricated body layer, a raw material of a fourth porous ceramic prefabricated body layer and a raw material of a fifth porous ceramic prefabricated body layer to obtain mixed raw materials correspondingly;
step two, sequentially placing the mixed raw material of the first porous ceramic prefabricated body layer, the mixed raw material of the second porous ceramic prefabricated body layer, the mixed raw material of the third porous ceramic prefabricated body layer, the mixed raw material of the fourth porous ceramic prefabricated body layer and the mixed raw material of the fifth porous ceramic prefabricated body layer in a mold, pressurizing to 110kN, keeping for 3min, and relieving the pressure to obtain a green body; the thickness of each layer of mixed raw materials laid in the mould is 20 mm;
step three, under the vacuum environment, heating the green body to 1900 ℃ according to the heating rate of 30 ℃/min, and keeping the temperature for 5 hours for sintering; the vacuum degree of the vacuum environment is 450 Pa; step three also comprises applying a pressure of 90kN to the green body during sintering
And step four, cooling the sintered blank along with the furnace to obtain the gradient porous ceramic prefabricated body.
The composition and porosity of the raw material for each layer in the gradient porous ceramic preform of this example are shown in Table 2.
TABLE 2 parameters of gradient porous ceramic preform of example 2
As can be seen from table 2, the gradient porous ceramic preform of the present example has a single-layer porosity that increases layer by layer.
Example 3
The present embodiment provides a gradient porous ceramic preform, including a first porous ceramic preform layer, a second porous ceramic preform layer, a third porous ceramic preform layer, a fourth porous ceramic preform layer, and a fifth porous ceramic preform layer, which are sequentially disposed;
and the porosity of the first porous ceramic preform layer, the porosity of the second porous ceramic preform layer, the porosity of the third porous ceramic preform layer, the porosity of the fourth porous ceramic preform layer and the porosity of the fifth porous ceramic preform layer are increased in sequence.
The thickness of the first porous ceramic preform layer, the thickness of the second porous ceramic preform layer, the thickness of the third porous ceramic preform layer, the thickness of the fourth porous ceramic preform layer and the thickness of the fifth porous ceramic preform layer are all 20 mm.
The raw materials of the first porous ceramic preform layer, the second porous ceramic preform layer, the third porous ceramic preform layer, the fourth porous ceramic preform layer and the fifth porous ceramic preform layer respectively comprise boron oxide, graphene, lutetium oxide and aluminum oxide;
in the raw materials of the first porous ceramic material layer, the mass percentage of boron oxide is 56%, the mass percentage of graphene is 34%, the mass percentage of lutetium oxide is 5%, and the mass percentage of aluminum oxide is 5%;
in the raw materials of the second porous ceramic material layer, the mass percentage of boron oxide is 57%, the mass percentage of graphene is 35%, the mass percentage of lutetium oxide is 4%, and the mass percentage of aluminum oxide is 4%;
in the raw materials of the third porous ceramic material layer, the mass percentage of boron oxide is 58%, the mass percentage of graphene is 36%, the mass percentage of lutetium oxide is 3%, and the mass percentage of aluminum oxide is 3%;
in the raw materials of the fourth porous ceramic material layer, the mass percentage of boron oxide is 59%, the mass percentage of graphene is 37%, the mass percentage of lutetium oxide is 2%, and the mass percentage of aluminum oxide is 2%;
in the raw materials of the fifth porous ceramic material layer, the mass percentage of boron oxide is 60%, the mass percentage of graphene is 38%, the mass percentage of lutetium oxide is 1%, and the mass percentage of aluminum oxide is 1%;
particle diameter D of the boron oxide1D is more than 10 mu m1<20μm，B2O3The content is more than 99 percent;
particle diameter D of the graphene2D is more than 5 mu m2<10 mu m, the specific surface area of the graphene is 180m2/g～280m2The C content of the graphene is 80-90%;
the particle size D of the lutetium oxide3D is more than 5 mu m3<10μm，Lu2O3The content is more than 99 percent;
the particle diameter D of the alumina4D is more than 5 mu m4<10μm，Al2O3The content is more than 99 percent.
In addition, the present embodiment also provides a method for preparing the gradient porous ceramic preform, including:
step one, respectively carrying out wet ball milling drying on a raw material of a first porous ceramic prefabricated body layer, a raw material of a second porous ceramic prefabricated body layer, a raw material of a third porous ceramic prefabricated body layer, a raw material of a fourth porous ceramic prefabricated body layer and a raw material of a fifth porous ceramic prefabricated body layer to obtain mixed raw materials correspondingly;
step two, sequentially placing the mixed raw material of the first porous ceramic prefabricated body layer, the mixed raw material of the second porous ceramic prefabricated body layer, the mixed raw material of the third porous ceramic prefabricated body layer, the mixed raw material of the fourth porous ceramic prefabricated body layer and the mixed raw material of the fifth porous ceramic prefabricated body layer in a mold, pressurizing to 120kN, keeping for 4min, and relieving the pressure to obtain a green body; the thickness of each layer of mixed raw materials laid in the mould is 25 mm;
step three, under the vacuum environment, raising the temperature of the green body to 2000 ℃ according to the heating rate of 40 ℃/min, and keeping the temperature for 6 hours for sintering; thirdly, the vacuum degree of the vacuum environment is 500 Pa; step three, applying pressure of 100kN to the green body in the sintering process;
and step four, cooling the sintered blank along with the furnace to obtain the gradient porous ceramic prefabricated body.
The composition and porosity of the raw material for each layer in the gradient porous ceramic preform of this example are shown in Table 3.
TABLE 3 parameters of gradient porous ceramic preform of example 3
As can be seen from table 3, the gradient porous ceramic preform of the present example has a single-layer porosity that increases layer by layer.
Example 4
The embodiment provides an aluminum alloy toughened ceramic composite material for an elevator safety gear wedge, which comprises an aluminum alloy and the composite material of the embodiment 1, wherein the aluminum alloy is ZL 101.
The embodiment also provides a method for preparing the aluminum alloy toughened ceramic composite material for the elevator safety gear wedge block, which comprises the following steps:
step one, coating a release agent in a pressure chamber of a die casting machine so as to facilitate demoulding;
step two, placing the gradient porous ceramic preform in the embodiment 1 into a pressure chamber, and preheating the pressure chamber to 500 ℃;
pouring molten aluminum alloy liquid into the pressure chamber until the pressure chamber is filled with the molten aluminum alloy liquid; the molten aluminum alloy liquid is obtained by melting aluminum alloy at the temperature of more than or equal to 750 ℃, and the preferred melting temperature is 750-850 ℃;
step four, vacuumizing a pressure chamber to less than 200Pa, pressurizing the pressure chamber filled with molten aluminum alloy liquid and the gradient porous ceramic prefabricated body to 40MPa, keeping for 15 minutes to press the molten aluminum alloy liquid into the composite material, and stopping pressurizing;
step five, cooling, demolding to obtain an ingot, re-melting the ingot to remove redundant aluminum alloy, and taking out; the temperature of the remelting is preferably 800 ℃;
sixthly, carrying out heat treatment on the re-melted material to obtain the aluminum alloy toughened ceramic composite material for the elevator safety tongs wedge block; the heat treatment comprises: putting the re-melted material into a muffle furnace, heating the furnace temperature to 500 ℃ from room temperature within 0.6h, preserving the temperature for 5h, taking out, quenching with water, and preserving the temperature for 4h at 160 ℃; the aluminum alloy toughened ceramic composite material structure is shown in fig. 1 and comprises a first aluminum toughened porous ceramic layer 1, a second aluminum toughened porous ceramic layer 2, a third aluminum toughened porous ceramic layer 3, a fourth aluminum toughened porous ceramic layer 4 and a fifth aluminum toughened porous ceramic layer 5 which are sequentially arranged.
The single-layer microhardness and impact toughness of the aluminum alloy toughened ceramic composite material of the present example are shown in table 4. Wherein, the test of the single-layer microhardness and the impact toughness are respectively based on the mechanical property test of a welding test piece of a pressure-bearing equipment product (GB/T229-2007), each group comprises three test samples, an average value is taken, and the Vickers hardness test part 1 of GB/T4340.1-2009 metal material: test method, namely preparing a sample into a metallographic sample, measuring the microhardness of the sample by using a microhardness meter, measuring the microhardness of the sample within a test force range of 200gf, measuring an experimental load of 200g, measuring the loading time of 15s, measuring 6 points of the hardness of each part, and taking an average value.
TABLE 4 Single layer microhardness and impact toughness of the aluminum alloy toughened ceramic composite of example 4
The aluminum alloy toughened ceramic composite material has extremely high-temperature abrasion and wear resistance and impact resistance, and can meet the requirements of the working environment of the wedge block material of the elevator safety gear.
The aluminum alloy toughened ceramic composite material of embodiment 4 is loaded into an elevator system as a safety gear wedge block, so that the first layer is close to a guide rail, the fifth layer is close to a base, the hardness is gradually reduced from the safety gear wedge block working surface which is mutually rubbed with the elevator guide rail to the fixing surface of the safety gear wedge block fixed with the base, the impact toughness is gradually increased, the safety gear wedge block working part which is mutually rubbed with the elevator guide rail has excellent frictional wear resistance, and the safety gear wedge block base part which is fixed with the base has excellent impact resistance.
Fig. 2 is a scanning electron microscope image of the aluminum alloy toughened ceramic composite material according to the embodiment, and it can be seen from fig. 2 that the microstructure of the aluminum alloy toughened ceramic composite material is dense and has no casting defect, the pores of the aluminum alloy in the boron carbide ceramic porous gradient preform are completely filled, the boron carbide ceramic reinforcing particles are fine and equiaxial, and are uniformly distributed, indicating that the aluminum alloy toughened ceramic composite material of the present invention has an excellent microstructure.
Example 5
The embodiment provides an aluminum alloy toughened ceramic composite material for an elevator safety gear wedge, which comprises an aluminum alloy and the composite material of the embodiment 2, wherein the aluminum alloy is ZL 102.
The embodiment also provides a method for preparing the aluminum alloy toughened ceramic composite material for the elevator safety gear wedge block, which comprises the following steps:
step one, coating a release agent in a pressure chamber of a die casting machine so as to facilitate demoulding;
step two, placing the gradient porous ceramic preform of the embodiment 2 in a pressure chamber, and preheating the pressure chamber to 600 ℃;
pouring molten aluminum alloy liquid into the pressure chamber until the pressure chamber is filled with the molten aluminum alloy liquid; the molten aluminum alloy liquid is obtained by melting aluminum alloy at the temperature of more than or equal to 750 ℃, and the preferred melting temperature is 750-850 ℃;
step four, vacuumizing a pressure chamber to less than 200Pa, pressurizing the pressure chamber filled with molten aluminum alloy liquid and the gradient porous ceramic prefabricated body to 50MPa, keeping for 10 minutes to press the molten aluminum alloy liquid into the composite material, and stopping pressurizing;
step five, cooling, demolding to obtain an ingot, re-melting the ingot to remove redundant aluminum alloy, and taking out; the temperature of the remelting is preferably 800 ℃;
sixthly, carrying out heat treatment on the re-melted material to obtain the aluminum alloy toughened ceramic composite material for the elevator safety tongs wedge block; the heat treatment comprises: and (3) putting the re-melted material into a muffle furnace, heating the furnace temperature to 600 ℃ from the room temperature within 0.8h, preserving the heat for 6h, taking out, quenching with water, and preserving the heat for 6h at 180 ℃.
The single-layer microhardness and impact toughness of the aluminum alloy toughened ceramic composite material of this example are shown in table 5, and the single-layer microhardness and impact toughness test methods are the same as those of example 4.
TABLE 5 Single layer microhardness and impact toughness of the aluminum alloy toughened ceramic composites of example 5
Single layer microhardness Hv
Single layer impact toughness J
Layer 1
884
21
Layer 2
741
30
Layer 3
672
36
Layer 4
609
40
Layer 5
538
43
The aluminum alloy toughened ceramic composite material has extremely high-temperature abrasion and wear resistance and impact resistance, and can meet the requirements of the working environment of the wedge block material of the elevator safety gear.
The morphology of the aluminum alloy toughened ceramic composite material of the embodiment is basically the same as that of the embodiment 4.
Example 6
The embodiment provides an aluminum alloy toughened ceramic composite material for an elevator safety gear wedge, which comprises an aluminum alloy and the composite material of the embodiment 3, wherein the aluminum alloy is ZL 101.
The embodiment also provides a method for preparing the aluminum alloy toughened ceramic composite material for the elevator safety gear wedge block, which comprises the following steps:
step one, coating a release agent in a pressure chamber of a die casting machine so as to facilitate demoulding;
step two, placing the gradient porous ceramic preform of the embodiment 3 in a pressure chamber, and preheating the pressure chamber to 700 ℃;
pouring molten aluminum alloy liquid into the pressure chamber until the pressure chamber is filled with the molten aluminum alloy liquid; the molten aluminum alloy liquid is obtained by melting aluminum alloy at the temperature of more than or equal to 750 ℃, and the preferred melting temperature is 750-850 ℃;
step four, vacuumizing a pressure chamber to less than 200Pa, pressurizing the pressure chamber filled with molten aluminum alloy liquid and the gradient porous ceramic prefabricated body to 60MPa, keeping for 20 minutes to press the molten aluminum alloy liquid into the composite material, and stopping pressurizing;
step five, cooling, demolding to obtain an ingot, re-melting the ingot to remove redundant aluminum alloy, and taking out; the temperature of the remelting is preferably 800 ℃;
sixthly, carrying out heat treatment on the re-melted material to obtain the aluminum alloy toughened ceramic composite material for the elevator safety tongs wedge block; the heat treatment comprises: and (3) putting the re-melted material into a muffle furnace, heating the furnace temperature to 700 ℃ from the room temperature within 1.0h, preserving the heat for 7h, taking out, quenching with water, and preserving the heat for 8h at 200 ℃.
The single-layer microhardness and impact toughness of the aluminum alloy toughened ceramic composite material of this example are shown in table 6, and the single-layer microhardness and impact toughness test methods are the same as those of example 4.
TABLE 6 Single layer microhardness and impact toughness of the aluminum alloy toughened ceramic composite of example 6
Single layer microhardness Hv
Single layer impact toughness J
Layer 1
890
20
Layer 2
755
28
Layer 3
679
35
Layer 4
621
38
Layer 5
545
41
The aluminum alloy toughened ceramic composite material has extremely high-temperature abrasion and wear resistance and impact resistance, and can meet the requirements of the working environment of the wedge block material of the elevator safety gear.
The morphology of the aluminum alloy toughened ceramic composite material of the embodiment is basically the same as that of the embodiment 4.
Performance evaluation:
the results of the abrasion loss in the experimental tests of the frictional abrasion of the aluminum alloy toughened ceramic composite material in the embodiments 4 to 6 are shown in table 7, wherein the applied load is 50N, the rotation speed is 1500r/min, and the results are performed by using a frictional abrasion tester. It can be observed from table 7 that under the same frictional wear test conditions, the wear loss of the aluminum alloy toughened ceramic composite material is far less than 45 steel after being reinforced by boron carbide, which indicates that the aluminum alloy toughened ceramic composite material can meet the safe use requirement of the elevator safety gear wedge block and can effectively prolong the service life of the elevator safety gear wedge block.
TABLE 7 abrasion loss in experimental test of frictional abrasion of the aluminum alloy toughened ceramic composite material in examples 4 to 6
Sample (I)
Abrasion 20h (mg)
Abrasion 40h (mg)
Abrasion 60h (mg)
45 steel
72
89
103
Example 4
56
67
72
Example 5
54
66
70
Example 6
55
65
70
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.