CN1057514C

CN1057514C - Al2O3-base series composite materials and prepn. thereof

Info

Publication number: CN1057514C
Application number: CN96108389A
Authority: CN
Inventors: 周曦亚; 邓再德; 刘登坤
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 1996-07-05
Filing date: 1996-07-05
Publication date: 2000-10-18
Anticipated expiration: 2016-07-05
Also published as: CN1145346A

Abstract

The present invention relates to Al2 O3 base composite materials and a preparation method thereof Al2 O3 Al-Si-Mg(Zn)-X and a composite material containing an enhanced ceramic phase of the Al2 O3 Al-Si-Mg(Zn)-X are formed by that an aluminium alloy melt and a SiO2 prefabrication body or a sio2 prefabrication body containing the enhanced ceramic phase react and permeates under the condition of no shielding gas atmosphere at the temperature of 900 to 1200 DEG C, and the dimension of the formed composite material is precise, the shape and the dimension are basically identical with the shape and the dimension of the prefabrication body. In the composite material containing the enhanced ceramic phase, the maximum ceramic content is can achieve 92 vol%. The Al2 O3 base composite material provided by the present invention has the advantages of excellent performance, simple process, low price of raw materials, low process temperature, simple equipment and low cost.

Description

Alumina-based composite material and preparation method thereof

The invention relates to an inorganic material and a preparation method thereof, in particular to Al₂O₃A base composite material and a preparation method thereof.

Due to Al₂O₃The ceramic not only has high hardness and strength, good heat resistance and chemical stability, but also has lower price than other ceramic materials, therefore, Al₂O₃Is widely used in industry, such as the mill of a ball millBalls, and porcelain insulators, etc.

Despite the conventional Al₂O₃Ceramics have many excellent basic properties, but still suffer from the following disadvantages, which are unsatisfactory as structural materials:

(1) poor processability due to high hardness (mohs hardness 9);

(2) the brittleness is high, and the mechanical impact resistance is poor;

(3) due to poor machinability, it is difficult to form precise dimensions;

(4) the sintering temperature is high (1500-1900 ℃);

(5) sintering shrinkage is large;

(6) the thermal shock resistance is poor;

(7) the lubricity is inferior to that of metals.

U.S. Pat. No. 4, 4,673,435, issued to Toshiba ceramics, Japan, discloses Al₂O₃Since the composite material is formed by reaction infiltration of a pure aluminum melt with quartz glass, it is composed of a three-dimensionally interconnected matrix α -Al₂O₃And the material is composed of reticular aluminum alloy, has a unique microstructure, and has the strength of 400 MPa. Under the same conditions, they were also passed through an aluminum melt with SiO₂Reaction infiltration of SiC-bonded preforms to form SiC/Al₂O₃The strength of the/Al-Si composite material reaches 400 MPa.

However, Al₂O₃Al-Si and SiC/Al₂O₃The preparation of the/Al-Si composite material must be carried out at 780-1000 ℃ under vacuum or inert atmosphere, the equipment is complex, the operation cost is high, the raw material (quartz glass) is expensive, and the preparation method is not suitable for large-scale production.

The invention aims to overcome the defects in the prior art and provide Al with excellent performance₂O₃A ceramic matrix composite material and a method for preparing the same are provided. The method can obtain various complex-shaped ceramic composites with excellent performance and accurate size, has simple process method and does not need protective atmosphere,the process temperature is low, the equipment is simple, and the raw materials for preparing the material are low in price and low in preparation cost.

The aim of the invention is achieved by the following measures:

porous Al connected by three dimensions₂O₃Al of base body and aluminum alloy₂O₃Composite material, characterized in that it is composed of three-dimensionally interconnected Al₂O₃Base body of Al₂O₃、SiC、Si₃N₄、ZrO₂Particles or fibres or crystals of mulliteAny one of the whiskers consists of three main parts, namely a reinforced ceramic phase and an Al-Si-Mg-X or Al-Si-Zn-X alloy phase, wherein X is Fe or Cu or Ti or Ni metal element.

Porous Al connected by three dimensions₂O₃The alumina-based composite material composed of a matrix and aluminum alloy is characterized by comprising three-dimensionally communicatedAl₂O₃Base body of Al₂O₃、SiC、Si₃N₄、ZrO₂Any one of the mullite particles or fibers or whiskers is composed of a reinforced ceramic phase and an Al-Si-Mg-X or Al-Si-Zn-X alloy phase, wherein X is Fe or Cu or Ti or Ni metal element; three-dimensionally connected Al₂O₃The content of the matrix is 20-82%, the content of the reinforced ceramic phase is 0-70 wt%, and the content of the aluminum alloy phase is 8-50 wt%; wherein, in the aluminum alloy phase, the content of Al is 70-99 wt%, the content of Si is 0.5-10 wt%, the content of Mg or Zn is 0.1-10 wt%, and the content of X is 0-30 wt%.

Al₂O₃The preparation method of the base composite material is characterized by comprising the following steps and process conditions:

(1) preparation of preforms

25 to 95 weight percent of quartz powder or quartz glass waste or SiO with the purity of more than 98 percent₂Grinding a chemical reagent, and doping 0-65 wt% of Al₂O₃Or SiC or Si₃N₄Or ZrO₂Or mullite particles, fibers or whiskers and 5-10 wt% of kaolin bonding agent, and sintering the mixture into a preform after molding;

(2) preparation of an aluminium alloy melt

Smelting and casting Al-Mg-X or Al-Zn-X alloy from pure aluminum blocks or leftover materials of aluminum alloy or recycled waste alloy, wherein the content of Al is 83-99 wt%, the content of Mg or Zn is 0.1-10 wt%, X is Fe or Cu or Ni or Ti, and the content is 0-10 wt%, and the batch materials are put into a crucible and smelted into melt at 720-800 ℃;

(3)Al₂O₃preparation of base composite materials

Firstly, preheating the preform prepared in the step (1), immersingthe preform into the aluminum alloy melt in the step (2), then heating to 900-1200 ℃, preserving heat under the protection of no atmosphere, and reacting for 1-15 hours to form the composite material.

AL formed by the above method₂O₃In the matrix composite, α -Al₂O₃The matrix is a network body containing a large number of three-dimensionally connected pores, and the aluminum alloy is filled in the pores to make the pores compact. The prefabricated body is divided into two types of doping and non-doping, namely, the prefabricated body is divided into a reinforced ceramic phase and can not contain the reinforced ceramic phase. In Al without reinforcing ceramic phase₂O₃In the matrix composite, Al₂O₃The content is 50-75 Vol%, and the content of metal is 25-50 Vol%. The ratio of metal/ceramic can be adjusted by the compactness of the preform, the denser the preform, the higher the ceramic content in the formed ceramic composite material. In SiO₂The preform being doped with a ceramic which is relatively inert to aluminium (e.g. Al)₂O₃、SiC、Si₃N₄、ZrO₂Etc.), the ceramic content of the composite material can be increased, and the ceramic content in the formed composite material can reach 92Vol at most. Doping of TiO in preforms₂Can ensure that Al and TiO react and permeate in the process of reaction and permeation of the Al liquid and the prefabricated body₂The reaction is carried out, and the reaction is carried out, 。

the alloy or intermetallic compound formed by Ti, Al and Si can improve the melting point of the alloy, and is beneficial to the high-temperature application of the material.

Compared with the prior art, the invention has thefollowing outstanding advantages:

1. al of the invention₂O₃The ceramic content of the base composite material can reach 92Vol% at most, and the melting point of the metal phase can be improved due to the alloy or intermetallic compound formed by Ti, Al and Si, so that the base composite material is more suitable for high-temperature application.

2. Preforms containing a reinforced ceramic fiber phase having enhanced Al₂O₃The strength and toughness of the base composite material are as high as 850MPa in bending strength and 16 MPa.m in fracture toughness^1/2The Vickers hardness reaches 18 GPa.

3. Al prepared by the invention₂O₃The ratio of ceramic to metal content in the base composite material is adjustable, and ceramic phase (such as SiC and Al) can be doped₂O₃、Si₃N₄、ZrO₂Etc.), or can be mixed with hybrid gold elements (Fe, Cu, Ni, Ti, etc.) to adjust the properties of the material.

4. Preparation of Al₂O₃The raw materials of the base composite material are low in price and abundant in sources, and leftover materials of aluminum alloy and recycled waste aluminum alloy, quartz glass waste and quartz ore can be used as raw materials.

5. The invention has simple preparation process, does not need protective atmosphere, has low process temperature, simple equipment and obviously reduced product cost.

6. The shape and size of the composite material prepared by the method are basically the same as those of a prefabricated body, and the size is accurate.

The invention will be further described in detail with reference to the following examples:

example1

1. Preparation of preforms

Taking 90 wt% of quartz mineral powder with the purity of more than 98%, adding 10 wt% of kaolin, molding and sintering;

2. preparation of an aluminium alloy melt

Putting Al98 wt% and Zn2 wt% into a crucible made of cordierite-mullite or clay-mullite refractory materials, and heating to 720 ℃ in an air atmosphere to melt;

3、Al₂O₃preparation of/Al-Si-Zn composite material

The high-temperature SiO prepared in the step 1₂Immersing the prefabricated body into the aluminum alloy liquid prepared in the step 2, heating to 1125 ℃, preserving the heat without any protective atmosphere, reacting for 6 hours, and enabling Al and SiO₂According to the following chemical equation:

form α -Al₂O₃And Si, α -Al₂O₃In a three-dimensionally connected network structure, at α -Al₂O₃In which Al-Si-Zn alloy is distributed. Thus, Al is obtained₂O₃A base composite material. Zn in the master alloy can improve the wetting of the aluminum melt to the preform and can react with O in the preform through evaporation₂ZnO is formed by reaction, so that a certain vacuum degree is formed in the prefabricated body, and the infiltration capacity of the aluminum melt to the prefabricated body is improved.

The material is taken out of the melt and blown off from the surface of the aluminum melt by blowing air from a blower at a high temperature of 800 ℃. Al (Al)₂O₃the/Al-Si-Zn composite material contains 25 wt% of Al, 3.5 wt% of Si, 1.5 wt% of Zn,70 wt% of Al₂O₃The bending strength of the material is 380MPa, the Vickers hardness is 14.5GPa, and the fracture toughness is 5.2 MPa.m^1/2。

Example 2

1. Preparation of preforms

A prefabricated body made of commercial quartz glass is adopted;

2. preparation of an aluminium alloy melt

Putting 99 wt% of Al and 1 wt% of Mg into a crucible, and heating to 720 ℃ in an air atmosphere for melting;

3、Al₂O₃preparation of/Al-Si-Mg composite material

Immersing the high-temperature quartz glass preform prepared in the step 1 into the aluminum alloy melt prepared in the step 2, heating to 1000 ℃, and carrying out heat preservation reaction for 3 hours, wherein the reaction equation is as follows:

form Al₂O₃/Al-Si-Mg composite material, and removing the aluminum melt on the surface of the material by adopting the method of example 1. Chemical analysis shows that Al in the material₂O₃71 wt% of Al, 5.5 wt% of Si and 0.5 wt% of Mg, the bending strength of the material is 390MPa, and the fracture toughness is 5.1 MPa.m^1/2。

Example 3

1. Preparation of preforms

Mixing 95 wt% of quartz glass waste and 5 wt% of kaolin, ball-milling, molding and sintering to form a compact ceramic preform;

2. preparation of an aluminium alloy melt

Taking leftover materials of Al-Zn alloy as main raw materials, adding a proper amount of Fe, and smelting the mixture at 720 ℃ to obtain an aluminum alloy melt containing 83 wt% of Al10 wt% of Zn and 7 wt% of Fe;

3、Al₂O₃preparation of/Al-Si-Zn-Fe composite material

Preheating the prefabricated body prepared in the step 1, then immersing the prefabricated body into the aluminum alloy melt in the step 2, heating to 1050 ℃, and preserving heat for 3 hours to perform the following reactions:

thereby preparing Al₂O₃The Al-Si-Zn-Fe composite material. The aluminum alloy melt on the surface of the material was removed by the method of example 1. The material contains 76 wt% of Al₂O₃14 wt% Al, 5.4 wt% Si, 0.6 wt% Zn and 4 wt% Fe. The bending strength of the material is 410MPa, and the Vickers hardness is 13.8 GPa.

Example 4

1. Preparation of preforms

65 wt% of industrial Al₂O₃25 wt% quartz ore (containing 98% SiO)₂) Mixing with 10 wt% of kaolin, ball-milling and sintering to form a compact ceramic body;

2. preparation of an aluminium alloy melt

Smelting Al-2% Zn alloy melt at 720 ℃ by taking Al-Zn alloy leftover materials as main raw materials;

3、Al₂O₃preparation of/Al-Si-Zn based composite material

Preheating the prefabricated body prepared in the step 1, then immersing the prefabricated body into the aluminum alloy melt in the step 2, heating to 1200 ℃, and preserving heat for 7 hours to perform the following reactions:

preparing Al₂O₃The ceramic content of the/Al-Si-Zn composite material is 90.76 Vol%, the bending strength is 413.6MPa, and the Vickers hardness is 18.9 GPa.

Example 5

1. Preparation of preforms

Taking pure SiO₂90 wt% of quartz glass with the content of more than 98%, adding 8 wt% of SiC fiber as a reinforced ceramic phase, doping 2 wt% of clay as a bonding agent, molding and sintering to obtain the product;

2. preparation of an aluminium alloy melt

Putting 95 wt% of Al and 5 wt% of Zn into a crucible, and heating to 720 ℃ for melting;

3、SiC_f/Al₂O₃preparation of/Al-Si-Zn composite material

Immersing the high-temperature preform of the reinforced ceramic phase prepared in the step 1 into the aluminum alloy melt prepared in the step 2, heating to 1035 ℃, preserving the temperature and reacting for 3 hours, wherein the reaction equation is the same as that of the example 1, and removing the melt on the surface of the composite material by the method shown in the example 1 to obtain SiC_f/Al₂O₃The Al-Si-Zn composite material has a bending strength of 850MPa and a fracture toughness of 16 MPa-m^1/2。

Example 6

1. Preparation of preforms

Taking SiO₂95 wt% of quartz sand with the content of more than 98%, 5 wt% of kaolin is doped, and the quartz sand is sintered into a prefabricated body at high temperature;

2. preparation of an aluminium alloy melt

Al-Zn alloy and Al-Ti alloy leftover materials are used as main ingredients and are smelted into Al-1 percent Zn-10 percent Ti (weight ratio) alloy melt at 800 ℃;

3、Al₂O₃preparation of/Al-Zn-Si-Ti composite material

Preheating the prefabricated body prepared in the step 1, then immersing the prefabricated body into the aluminum alloy melt in the step 2, heating to 1175 ℃, and preserving heat for 6 hours to perform the following reactions:

form Al₂O₃The bending strength of the/Al-Zn-Si-Ti composite material is 418.3MPa and K_ICIs 5.7MPa · m^1/2The hardness was 18.1 GPa. The X-ray diffraction analysis shows that the composite material contains Al, Si and Al₃A Ti phase.

Claims

1. Porous Al connected by three dimensions₂O₃The alumina-based composite material composed of a matrix and aluminum alloy is characterized by comprising three-dimensionally communicated Al₂O₃Base body of Al₂O₃、SiC、Si₃N₄、ZrO₂Any one of the mullite particles or fibers or whiskers is composed of a reinforced ceramic phase and an Al-Si-Mg-X or Al-Si-Zn-X alloy phase, wherein X is Fe or Cu or Ti or Ni metal element; three-dimensionally connected Al₂O₃The content of the matrix is 20-82%, the content of the reinforced ceramic phase is 0-70 wt%, and the content of the aluminum alloy phase is 8-50 wt%; wherein, in the aluminum alloy phase, the content of Al is 70-99 wt%, the content of Si is 0.5-10 wt%, the content of Mg or Zn is 0.1-10 wt%, and the content of X is 0-30 wt%.

2、Al₂O₃The preparation method of the base composite material is characterized by comprising the following steps and process conditions:

(1) preparation of preforms

25to 95 weight percent of quartz powder or quartz glass waste or SiO with the purity of more than 98 percent₂Grinding a chemical reagent, and doping 0-65 wt% of Al₂O₃Or SiC or Si₃N₄Or ZrO₂Or mullite particles, fibers or whiskers and 5-10 wt% of kaolin bonding agent, and sintering the mixture into a preform after molding;

(2) preparation of an aluminium alloy melt

(3)Al₂O₃preparation of base composite materials

Firstly, preheating the preform prepared in the step (1), immersing the preform into the aluminum alloy melt in the step (2), then heating to 900-1200 ℃, preserving heat under the protection of no atmosphere, and reacting for 1-15 hours to form the composite material.