Porous material with continuous porosity gradient and preparation method of porous material

Abstract

The invention provides a preparation method of a porous material with a continuous porosity gradient. The preparation method comprises the following steps: (1) mixing a raw powder material with the volume fraction of 50-70% and deionized water with the volume fraction of 30-50%, then adding sol, and performing ball milling to obtain a slurry A; (2) preparing a hydrosol B according to the same ratio as that in the step (1); (3) at regular time intervals, adding the hydrosol B into the slurry A to obtain a mixed slurry, keeping the solid phase content of the mixed slurry to change continuously in the range of 0-70vol%, inputting into a 3D printer for printing each time after addition of the hydrosol B, and keeping solidifying the mixed slurry at a nozzle into gel; (4) freezing the formed gel in a gradient direction, and sintering to form the porous material with the continuous porosity gradient. The invention has the beneficial effects as follows: the process is simple, and the stability and the repeatability are relatively good; through continuous adjustment of the slurry solid phase content and in combination with 3D printing, the gel with the continuous gradient solid content is formed.

Description

technical field [0001] The invention relates to a preparation method of a porous material, in particular to a porous material with a continuous gradient of porosity and a preparation method thereof. Background technique [0002] The porous material with porosity gradient is an important member of functionally graded materials, and its main feature is that the porosity changes regularly with the sample size. Gradient porous materials were first used in the fields of filtration, gas separation, dust removal, etc. Compared with traditional porous materials with uniform porosity, they can maximize efficiency and save energy consumption. In the field of filtration and separation, with the improvement of filtration precision, the pore size of porous materials is required to be smaller and smaller, but this leads to an increase in the resistance of fluid passing through the material, reducing its permeability. Traditional porous materials can no longer meet the needs of high-preci...

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Problems solved by technology

However, the existing preparation methods still have the following main problems: 1. Most of the gradient materials prepared by traditional methods have a step porosity gradient, and it is difficult to achieve a continuous gradient change in porosity, so that the gradient porous materials cannot be maximized. 2. The porosity gradient can be adjusted in a small range, and different gradient forms from low porosity (0%) to high porosity (above 80%) cannot be realized, which limits its application range; 3. There is no one It has a universal preparation method, which can meet the preparation of different gradient porous materials such as metals and ceramics; 4. The traditional method is complex in process, poor in stability and reproducibility of the production process, difficult to control the pore structure of porous materials, and difficult to achieve mass production

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