CN104387105A - Method for preparing porous alumina ceramic material through combination of 3D printing and reactive sintering - Google Patents

Abstract

The invention relates to a method for preparing a porous alumina ceramic material by combining 3D printing with reaction sintering, the method comprising: 1) Adding aluminum powder or aluminum alloy powder to a feeding box of a three-dimensional printer, and printing out a porous biscuit by the three-dimensional printer ; 2) The porous green body prepared in step 1) is sequentially solidified, debonded, oxidized, and sintered to obtain the porous alumina ceramic material.

Description

Method for preparing porous alumina ceramic materials by 3D printing combined with reaction sintering

technical field

The invention relates to a method for preparing a porous alumina ceramic material, which belongs to the technical field of porous ceramic material preparation.

Background technique

Porous alumina ceramics have light weight, high permeability, chemical corrosion resistance, friction resistance, low expansion coefficient and good high temperature stability, and have broad application prospects in high temperature gas and liquid filtration, catalyst carriers, heat insulation materials and other fields. According to the specific application requirements in different fields, the porosity and pore size of porous alumina ceramics can be designed, and there are many reports on related preparation methods. For example, porous alumina ceramics with porosity>50% are prepared by using alumina as aggregate, carbon powder and ethyl cellulose composite pore-forming agent (Chinese Patent, Patent No. CN101734909A). Aluminum nitrate, citric acid and water are mixed according to a certain ratio, reacted at 150-200°C, and calcined at a high temperature to prepare foamed alumina ceramics (Chinese patent, patent number CN101717105A). Using aluminum isopropoxide as a precursor, porous alumina ceramics are prepared by sol-gel-freeze drying process, with adjustable porosity of 30-97% and adjustable pore size of 1-100 μm (Chinese patent, patent number CN196257A). The above reports are all means of regulating the microstructure, and do not involve the preparation of complex shapes, especially those with complex macroscopic pore structures inside.

As a kind of rapid prototyping process, three-dimensional printing technology (3DP) can automatically, quickly, directly and accurately transform design ideas into prototypes with certain functions or directly manufacture parts (molds), effectively shortening the product development cycle. The first-time yield of product design and manufacturing is improved, and the cost of product development is reduced. 3DP technology adopts the inkjet method in printing technology. The nozzle selectively sprays the binder to the required position without directly contacting the powder surface, and bonds the parts layer by layer. This technology can realize the design and preparation of three-dimensional pore structure. However, the conventional 3DP method for preparing porous alumina is to mix fine alumina powder (~0.5 μm) and dextrin in distilled water, and then freeze-dry to obtain a loose granulated powder with a particle size distribution of 50-200 μm. Facilitate the spreading of 3DP layer-by-layer powder (MelcherR, Mater Lett 2006; 60:572-75). However, the shrinkage rate of the sample is about 20% during the post-sintering process, and it is difficult to realize the manipulation from prototype design to precise preparation, which greatly reduces the application value of 3DP.

Therefore, how to combine 3DP technology to prepare porous ceramic materials with low shrinkage rate is still an important research direction for those skilled in the field.

Contents of the invention

The present invention aims to overcome the defect of high shrinkage rate of the existing porous ceramic material prepared by 3DP technology, and provides a method for preparing porous alumina ceramic material by combining 3D printing with reaction sintering.

The invention provides a method for preparing a porous alumina ceramic material, the method comprising:

1) Add aluminum powder or aluminum alloy powder to the feeding box of the three-dimensional printer, and print out the porous green body through the three-dimensional printer;

2) The porous green body prepared in step 1) is sequentially subjected to solidification, debonding, oxidation, and sintering processes to obtain the porous alumina ceramic material.

Preferably, the aluminum alloy powder includes AlSi5 powder and/or AlSi12 powder.

Preferably, the particles in the aluminum powder or aluminum alloy powder are 10-25 μm spherical particles.

Preferably, in step 1), the parameters of the three-dimensional printing are: the thickness of the single layer of the porous green body is 50-200 μm, the saturation of the binder is 60-150%, and the binder includes ethylene glycol, ethylene glycol monolayer Butyl ether, and the mixture of these two binders, the drying time is 60-120s.

Preferably, in step 2), the parameters of the curing process are: at 100-120°C, heat preservation for 24-96 hours.

Preferably, in step 2), in the debonding process, the temperature is raised to 200-600° C. at a rate of 0.2-2° C./minute, and the holding time is 2-12 hours.

Preferably, in step 2), in the oxidation process, the temperature is raised to 550-1400° C. at a heating rate of 0.2-2° C./minute, and the holding time is 2-24 hours.

Preferably, in step 2), in the sintering process, the temperature is raised to 1550-1600° C. at a heating rate of 5-10° C./minute, and the holding time is 2-8 hours.

Beneficial effects of the present invention:

(1) 3DP can prepare products with complex shapes without molds, and the product has good uniformity and pore connectivity, and the pore diameter and porosity are controllable;

(2) The shape and size of the sample are basically unchanged before and after reaction sintering, effectively realizing the precise realization from design to final product.

Description of drawings

Fig. 1 shows the scanning electron micrographs of raw material powder Al (a) and AlSi12 (b) used in two embodiments of the present invention;

Fig. 2 shows the XRD patterns of the Al body and porous alumina ceramics prepared in two embodiments of the present invention;

Fig. 3 shows the cross-sectional scanning electron microscope pictures of the Al green body (a) and porous alumina ceramics (b) prepared in one embodiment of the present invention;

Fig. 4 shows the physical photographs of the Al green body (gray) and the porous alumina ceramics (white) prepared in one embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the drawings and the following embodiments. It should be understood that the drawings and the following embodiments are only used to illustrate the present invention rather than limit the present invention.

The purpose of the present invention is to provide a method with simple process and low cost to prepare porous aluminum with complex shape and excellent performance through 3D printing process, and to prepare porous alumina ceramic material by further reaction and sintering, so as to realize near-size molding and sintering to overcome Problems and deficiencies in the prior art. At the same time, AlSi alloy is selected, oxidized to generate Al ₂ O ₃ and SiO ₂ , and sintered to generate porous mullite bonded alumina.

The invention discloses a method for preparing a porous alumina ceramic material, which comprises the following steps: selecting a spherical metal aluminum powder prepared by an atomization method, preparing a porous aluminum body through a rapid prototyping process of a 3D printer, and oxidizing in an air atmosphere and Sintering obtains a porous alumina ceramic material. The invention provides a method with simple process and low cost to prepare porous alumina ceramics with complex shape and excellent performance, and has the advantages of forming and sintering in close size.

The invention provides a method for preparing a porous alumina ceramic material, which specifically includes the following steps:

(a) adding aluminum powder to a commercial three-dimensional printer feeding box;

(b) Load the three-dimensional image that needs to be printed in the computer, and start printing after adjusting the printing parameters;

(c) The printed porous body is cured in an oven;

(d) The cured sample is placed in a muffle furnace for binder removal, oxidation, and sintering to obtain porous alumina ceramics.

The metal powder described in the step (a) is Al and its alloys such as AlSi5, AlSi12 and the like.

The metal powder in step (a) is a spherical particle with a size of 10-25 μm.

The printing parameters described in step (b) are layer thickness of 50-200 μm, binder saturation of 60-150%, and drying time of 60-120 s.

The curing condition described in the step (c) is 100-120° C. for 24-96 hours.

The binder removal temperature described in step (d) is 200-600°C, and the heating rate is 0.2-2°C/min; the oxidation temperature is 550-1400°C, and the heating rate is 0.2-2°C/min; the sintering temperature is 1550-1600°C, the heating rate is 5-10°C/min.

Compared with the prior art, the present invention has the following beneficial effects:

(1) 3DP can prepare products with complex shapes without molds, and the product has good uniformity and pore connectivity, and the pore diameter and porosity are controllable;

(2) The shape and size of the sample are basically unchanged before and after reaction sintering, effectively realizing the precise realization from design to final product.

Some exemplary embodiments are further enumerated below to better illustrate the present invention. It should be understood that the above-mentioned embodiments described in detail in the present invention and the following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention, and those skilled in the art may make some non-essential improvements and improvements according to the above-mentioned contents of the present invention All adjustments belong to the protection scope of the present invention. In addition, the specific proportions, time, temperature, etc. in the following process parameters are only exemplary, and those skilled in the art can select appropriate values within the range defined above.

Example 1

(1) Add 10-25 μm Al powder (as shown in Figure 1 a) into a commercial 3D printer feeding box;

(2) The printing parameters are adopted as layer thickness 50 μm, binder saturation is 80%, binder is a mixture of 15% ethylene glycol and 85% ethylene glycol monobutyl ether, and the drying time is 60 s;

(3) The printed porous body is cured in an oven at 120°C for 24 hours;

(4) Put the cured sample into a muffle furnace for 2°C/min to 600°C to remove the binder (hold for 2 hours), 1°C/min to 1400°C for oxidation (hold for 6 hours), 5°C /min increased to 1600°C for sintering (4 hours of heat preservation), and finally obtained porous alumina ceramics with a bending strength of 74.8Mpa, a porosity of 45%, and a sample size increase of 0.6%;

As can be seen from Figure 2, the aluminum powder is completely oxidized, and the final product is an alumina ceramic material; it can also be seen from the photo in Figure 4 that the size of the porous alumina ceramic prepared in this embodiment is very close to the size of the green body, and there is no What a change.

Example 2

(1) Add 10-25 μm Al powder into a commercial 3D printer feeding box;

(2) The printing parameters are adopted as layer thickness 100 μm, binder saturation is 120%, binder is a mixture of 15% ethylene glycol and 85% ethylene glycol monobutyl ether, and the drying time is 90s;

(3) The printed porous body is cured in an oven at 120°C for 24 hours;

(4) Put the cured sample into a muffle furnace for 1°C/min to 600°C to remove the binder (hold for 2 hours), 1°C/min to 1400°C for oxidation (hold for 12 hours), 5°C /min increased to 1600°C for sintering (holding temperature for 2 hours), and finally obtained porous alumina ceramics with a bending strength of 71.3Mpa, a porosity of 44%, and a sample size increase of 0.8%;

It can be seen from Figure 2 that the aluminum powder is completely oxidized, and the final product is an alumina ceramic material; it can be seen from Figure 3 that the green body particles are densely packed, and there is a good sintering neck connection between the particles after sintering.

Example 3

(1) Add 20-25 μm AlSi5 powder into a commercial 3D printer feeding box;

(2) The printing parameters are adopted as layer thickness 75 μm, binder saturation is 80%, binder is a mixture of 15% ethylene glycol and 85% ethylene glycol monobutyl ether, and the drying time is 120s;

(3) The printed porous body is cured in an oven at 120°C for 24 hours;

(4) Put the cured sample into a muffle furnace for 2°C/min to 600°C to remove the binder (4 hours of heat preservation), 0.5°C/min to 1400°C for oxidation (24 hours of heat preservation), and 5°C/min The min was raised to 1600°C for sintering (4 hours of heat preservation), and finally a porous mullite-bonded alumina ceramic was obtained, with a flexural strength of 63.4Mpa, a porosity of 48%, and a sample size increase of 1.2%.

Example 4

(1) Add 20-25 μm AlSi12 powder (as shown in b in Figure 1) into a commercial three-dimensional printer feeding box;

(2) The printing parameters are adopted as layer thickness 150 μm, binder saturation is 120%, binder is a mixture of 15% ethylene glycol and 85% ethylene glycol monobutyl ether, and the drying time is 90s;

(3) The printed porous body is cured in an oven at 120°C for 24 hours;

(4) Put the cured sample into a muffle furnace and raise it to 600°C at 2°C/min to remove the binder (2 hours of heat preservation), rise to 1100°C at 0.3°C/min (8 hours of heat preservation), and 0.5°C/min Min rises to 1400°C for oxidation (4 hours of heat preservation), 5°C/min rises to 1600°C for sintering (4 hours of heat preservation), and finally obtains porous mullite-bonded alumina ceramics with a flexural strength of 60.2Mpa and a porosity of 47.5%. 1.1% increase in size.

Claims (8)

1. prepare a method for porous alumina ceramic material, it is characterized in that, described method comprises:

1) aluminium powder or Al alloy powder are added in the box for feeding odd of three-dimensional printer, print porous biscuit by three-dimensional printer;

2) porous biscuit step 1) prepared, successively through overcuring, unsticking, oxidation, sintering circuit, obtains described porous alumina ceramic material.

2. method according to claim 1, is characterized in that, described Al alloy powder comprises AlSi5 powder and/or AlSi12 powder.

3. method according to claim 1 and 2, is characterized in that, in described aluminium powder or Al alloy powder, particle is the spheroidal particle of 10-25 μm.

4., according to described method arbitrary in claim 1-3, it is characterized in that, in step 1), the parameter of 3 D-printing is: the thickness in monolayer of porous biscuit is 50-200 μm, binding agent saturation ratio is 60-150%, and binding agent comprises ethylene glycol and/or ethylene glycol monobutyl ether, and time of drying is 60-120s.

5., according to described method arbitrary in claim 1-4, it is characterized in that, step 2) in, the parameter of curing process is: at 100 ~ 120 DEG C, is incubated 24 ~ 96 hours.

6., according to described method arbitrary in claim 1-5, it is characterized in that, step 2) in, be warming up to 200-600 DEG C with the heat-up rate of 0.2-2 DEG C/min in debinding process, soaking time is 2-12 hours.

7., according to described method arbitrary in claim 1-6, it is characterized in that, step 2), be warming up to 550-1400 DEG C with the heat-up rate of 0.2-2 DEG C/min in oxidation operation, soaking time is 2-24 hours.

8., according to described method arbitrary in claim 1-7, it is characterized in that, step 2) in, be warming up to 1550-1600 DEG C with the heat-up rate of 5-10 DEG C/min in sintering circuit, soaking time is 2-8 hours.