The method for preparing porous alumina ceramic
Technical field
The present invention relates to the manufacturing technology of thermal insulation ceramics material, specifically is a kind of method for preparing porous alumina ceramic.
Background technology
Alumina-ceramic has good physical and chemical performance, as high-melting-point, high strength, high rigidity, high tenacity, excellent corrosion resisting performance and chemical stability.Therefore, aluminum oxide has obtained widespread use as structured material in a plurality of fields such as metallurgy, chemistry, the energy.Along with the expansion of aluminum oxide range of application, it is complicated that the shape of ceramic component is tending towards, and traditional moulding process is difficult to prepare the ceramic component of complicated shape, or the ceramic performance of preparation is relatively poor.The notes type (Gel-casting) that congeals into is a kind of new moulding process, this technology generates high molecular method with traditional ceramic preparation method in conjunction with organic monomer polymerization, utilize the organic monomer polymerization with ceramic powder suspensoid in-situ solidifying, the near net-shape ceramic component for preparing complicated shape afterwards through technological processs such as super-dry, binder removal, sintering, thereby in the close attention that has been subjected to people aspect forming process of ceramics and the preparation.But prior art does not still have desirable scheme for the heat-insulating capability of the stupalith that how to improve the injectiong coagulation shaping technology manufacturing.
Summary of the invention
Technical problem to be solved by this invention is, the method that can make the strong alumina-ceramic of complex configuration and heat-insulating capability is provided.
For achieving the above object, the technical solution used in the present invention is as follows:
A kind of method for preparing porous alumina ceramic comprises the steps:
A) be raw material with the aluminum oxide powder, add an amount of pore-forming material, adopt to annotate and coagulate technological forming;
B) with the biscuit after the moulding, at natural drying at room temperature 12-24 hour, then at 40-80 ℃ of dry 5-10 hour;
C) dried sample is inserted in the High Temperature Furnaces Heating Apparatus, in air atmosphere, be warming up to 600 ℃ with 1-3 ℃/minute speed, and be incubated 2-4 hour to remove pore-forming material; Be warming up to 1350~1550 ℃ with 2~25 ℃/minute speed then, be incubated 30~180 minutes and carry out high temperature sintering, namely obtain porous alumina ceramic.
As a kind of preferred version, described pore-forming material is starch, Graphite Powder 99 etc.
As a kind of preferred version, the granularity of described aluminum oxide and pore-forming material powder is 200~400 orders.
As a kind of preferred version, it is dispersion agent that described injectiong coagulation shaping technology adopts JA-281, add-on be in the slurry solid masses 0.8%~1.2%; Acrylamide is monomer, add-on be in the slurry solid masses 2%~4%; N-N ,-methylene tri propyl amides are linking agent, and add-on is 2%~4% of acrylamide quality; Tetramethyl Ethylene Diamine is catalyzer, and add-on is 0.5%~1% of slurry cumulative volume; Ammonium persulfate is initiator, and add-on is 5%~10% of Tetramethyl Ethylene Diamine quality.
As a kind of preferred version, in the ceramic size of preparation, the volume content of pore-forming material (pore-forming material content/total powder content) is 10~60%.
Compared with prior art, the present invention has following beneficial effect:
The present invention will annotate with fixed attention, and technology and porous material preparation technology combine; can prepare the porous alumina ceramic material with complex configuration; expanded the range of application of alumina material; its method not only has advantages such as raw material is cheap and easy to get, technology is simple, cost is low, suitable mass-producing; and prepared alumina-ceramic has lower thermal conductivity, excellent properties such as high porosity.
Embodiment
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only are used for explanation the present invention and unrestricted protection scope of the present invention.
Embodiment 1
Get the 60ml deionized water, splash into several ammoniacal liquor and regulate the pH value between 9-10, take by weighing 150g 400 purpose alumina-ceramic powders, and placing deionized water, the adjusting pH value is 9-10, adds the JA-281 of 3ml, and fully stir, add again 65g greater than 400 purpose starch as pore-forming material.Add 5.4g acrylamide and 0.25g N-N'-methylene tri propyl amides then, fully stir.The Tetramethyl Ethylene Diamine solution (50% concentration) that adds about 1.2ml more fully stirs and vacuum-treat on vacuum mixer, to eliminate the bubble in the slurry.Add at last the ammonium persulfate solution (5% concentration) of about 0.6ml in the slurry, after fully stirring fast, slurry inserted in the ready mould, leave standstill about 1 hour after, the sample of taking-up gelation.
With the biscuit after the moulding, natural drying at room temperature 24 hours, in 40 ℃ of baking ovens dry 5 hours then; Then sample is inserted in the High Temperature Furnaces Heating Apparatus, in air atmosphere, be warming up to 600 ℃ with 1 ℃/minute speed, and be incubated 2 hours to remove pore-forming material; Be warming up to 1500 ℃ with 5 ℃/minute speed then, be incubated 120 minutes and carry out high temperature sintering, namely obtain porous alumina ceramic.
Prepared porous alumina ceramic has the feature of the high pore of lower thermal conductivity, shows after the test that embodiment 1 prepared its thermal conductivity of porous alumina is 3.2W/mK, and volume density is 2.31g/cm
3This alumina-ceramic becomes typical porous pattern, and gas cell distribution is more even, and its median size is about 4 μ m.
Embodiment 2
Get the 50ml deionized water, splash into several ammoniacal liquor and regulate the pH value between 9-10, take by weighing 100g 300 purpose alumina-ceramic powders, and placing deionized water, the adjusting pH value is 9-10, adds the JA-281 of 3ml, and fully stir, add again 24g greater than 400 purpose Graphite Powder 99s as pore-forming material.Add 3.5g acrylamide and 0.15g N-N'-methylene tri propyl amides then, fully stir.The Tetramethyl Ethylene Diamine solution (50% concentration) that adds about 0.9ml more fully stirs and vacuum-treat on vacuum mixer, to eliminate the bubble in the slurry.Add at last the ammonium persulfate solution (5% concentration) of about 0.5ml in the slurry, after fully stirring fast, slurry inserted in the ready mould, leave standstill about 1 hour after, the sample of taking-up gelation.
With the biscuit after the moulding, natural drying at room temperature 20 hours, in 60 ℃ of baking ovens dry 8 hours then; Then sample is inserted in the High Temperature Furnaces Heating Apparatus, in air atmosphere, be warming up to 600 ℃ with 1 ℃/minute speed, and be incubated 4 hours to remove pore-forming material; Be warming up to 1500 ℃ with 2 ℃/minute speed then, be incubated 180 minutes and carry out high temperature sintering, namely obtain porous alumina ceramic.
Prepared porous alumina ceramic has the feature of the high pore of lower thermal conductivity, shows after the test that embodiment 1 prepared its thermal conductivity of porous alumina is 2.7W/mK, and volume density is 2.05g/cm
3
In sum as seen: adopt the inventive method can be at a lower temperature, synthetic lower thermal conductivity in the short period of time, high porosity has the alumina ceramic material of complex configuration.
Be necessary at last in this explanation to be: above embodiment only is used for technical scheme of the present invention is done explanation in further detail; can not be interpreted as limiting the scope of the invention, some nonessential improvement that those skilled in the art's foregoing according to the present invention is made and adjustment all belong to protection scope of the present invention.