阅读说明：本技术 一种梯度TiC多孔陶瓷的有机模板浸渍成形-无压烧结制备方法 (Organic template dip forming-pressureless sintering preparation method of gradient TiC porous ceramic ) 是由 周洋 韩晓楠 冯亦得 刘旭锋 张�成 李世波 黄振莺 李翠伟 于文波 翟洪祥 于 2019-10-15 设计创作，主要内容包括：本发明公开了一种以TiC、Ti和Mo粉为原料,采用有机模板浸渍成形-无压烧结工艺制备梯度TiC多孔陶瓷的方法。本方法将TiC粉、Ti粉、Mo粉、去离子水和PVB配制成料浆,通过有机模板浸渍法制备梯度TiC多孔陶瓷坯体,干燥后经无压烧结,得到梯度TiC多孔陶瓷。采用本发明的方法所制备的梯度TiC多孔陶瓷具有孔隙率高、孔径分布均匀、梯度层匹配可调、层间结合紧密、力学性能高等优点。(The invention discloses a method for preparing gradient TiC porous ceramic by taking TiC, Ti and Mo powder as raw materials and adopting an organic template dipping forming-pressureless sintering process. The method comprises the steps of preparing TiC powder, Ti powder, Mo powder, deionized water and PVB into slurry, preparing a gradient TiC porous ceramic blank by an organic template dipping method, drying, and sintering under no pressure to obtain the gradient TiC porous ceramic. The gradient TiC porous ceramic prepared by the method has the advantages of high porosity, uniform pore size distribution, adjustable gradient layer matching, tight interlayer combination, high mechanical property and the like.)

1. A method for preparing gradient TiC porous ceramic by adopting an organic template dip forming-pressureless sintering process is characterized by comprising the following steps: the preparation method comprises the following steps of combining polyurethane sponges with different apertures to form an organic template, mixing TiC powder, Ti powder, Mo powder, deionized water and PVB in a certain proportion to prepare slurry, placing the organic template in the slurry, dipping to obtain a gradient TiC porous ceramic blank, drying, and then performing pressureless sintering at high temperature to obtain gradient TiC porous ceramic, wherein the method specifically comprises the following steps:

1) pretreating polyurethane sponge with different pore diameters;

2) compounding the pretreated sponges with different apertures to obtain a gradient organic template;

3) weighing a certain amount of TiC powder, Ti powder, Mo powder, deionized water and PVB (polyvinyl butyral), and preparing slurry by ball milling and mixing;

4) putting the organic template prepared in the step 2) into the slurry prepared in the step 3) for dipping, and drying to obtain a gradient TiC porous ceramic blank;

5) and 4) sintering the blank obtained in the step 4) in a furnace to obtain the gradient TiC porous ceramic.

2. The method of claim 1, wherein step 1) the polyurethane sponge has a pore size ranging from 15PPI ((Pores Per inc)) to 90 PPI; the pretreatment method comprises the steps of soaking sponge in a 10% NaOH solution for 6-24 hours, and then placing the sponge in a CMC (sodium carboxymethylcellulose) solution for soaking for 12-36 hours.

3. The method of preparing a gradient TiC porous ceramic according to claim 1, wherein: the preparation method of the gradient organic template in the step 2) comprises the following steps: the polyurethane sponges with different pore diameters are combined together in the modes of sewing, glue bonding, resin bonding and the like.

4. The method for preparing gradient TiC porous ceramic according to claim 1, wherein the slurry in step 3) comprises the following raw materials by mass percent: 18-40 wt% of TiC powder, 9-20 wt% of Ti powder, 3-5 wt% of Mo powder, 3-10 wt% of PVB and the balance of deionized water; the ball milling method is roller ball milling, the ball-material ratio is 2:1, and the ball milling time is 12-24 hours.

5. The method of claim 1, wherein the step 4) comprises the following steps: and (3) completely immersing the organic template into the slurry, taking out the organic template, discharging redundant slurry in an extrusion or centrifugal rotation mode, repeating the steps for 3-5 times, and heating and drying at room temperature or in an oven to obtain a gradient TiC porous ceramic blank.

6. The method of preparing a gradient TiC porous ceramic according to claim 1, wherein: the sintering process conditions in the step 5) are as follows: the sintering temperature is 1600-1800 ℃, and the temperature is kept for 0.5-3 hours under the protection of vacuum or inert gas.

Technical Field

The invention relates to the technical field of inorganic nonmetallic materials, in particular to a method for preparing gradient TiC porous ceramic by using TiC powder, Ti powder and Mo powder as raw materials. More specifically, the invention relates to a method for preparing gradient TiC porous ceramic by adopting an organic template dipping forming-pressureless sintering process.

Background

The porous ceramic has the advantages of high porosity, high surface area, high chemical stability, low density, low thermal conductivity and the like, and is widely applied to the fields of heat insulation materials, dust removal and filtration, catalyst carriers and the like. At present, a great deal of research is carried out on porous ceramics at home and abroad, and the preparation method mainly comprises a pore-forming agent adding method, a particle stacking method, a foaming method, a sol-gel method, a hydrothermal synthesis method, a gel injection molding method, a self-propagating high-temperature synthesis method and the like. For example, the invention patent 'foam silicon carbide' (patent number 200610046242.X) takes SiC powder as raw material, the foam silicon carbide is prepared by a foaming method, and has higher hardness and wear resistance after being compounded with a matrix, and has wide application prospect in the fields of brake discs, friction and wear parts and the like. The invention discloses a TiC/Ti/Ni porous ceramic material (patent number 201611139323.4), which is prepared by taking Ti powder, Ni powder, graphite powder and cane sugar as raw materials through a self-propagating sintering method, has good mechanical properties, and has good application prospects in the fields of automobile exhaust treatment, filtration, purification, separation and the like.

At present, a great deal of research in related fields mainly focuses on the preparation and performance test of homogeneous porous materials, however, in many occasions requiring porous materials with different pore sizes, homogeneous porous materials often cannot meet the requirements of actual working conditions. The gradient material (FGM) means that in a three-dimensional space, the organization structure and performance of a material system are gradually changed through component design, thereby realizing that the function of the material is changed along a certain direction. Therefore, the FGM has many characteristics different from homogeneous materials, for example, two sides with different FGM characteristics can respectively meet the requirements of different working conditions, so that the FGM has wide application in the fields of catalysis, sensing, biology, fuel cells, sound absorption, food, environment and the like.

In the biological field, gradient materials are mainly applied to human bones at present. M.Thieme et al, university of Dresden, Germany, prepared gradient titanium alloys by a powder metallurgy method, which sintered Ti powder with large particle size under pressureless sintering at 1150 ℃ to form a preform, poured into the preform a suspension of fine Si powder mixed with an organic binder and a dispersant, and sintered at 1470 ℃ to obtain porous Ti alloys. The gradient material prepared by the method has a structure similar to natural bones, wherein the outer layer is compact, and the inner layer is loose and porous, so that the gradient material has better biocompatibility.

In the field of food processing, gradient porous materials are mainly used in food filtration. The gradient porous structure avoids the defects of low efficiency, complex flow and the like caused by single pore, and the food with different sizes can be filtered simultaneously by using one material, thereby greatly improving the efficiency and the quality. The scholars in China prepare 316L stainless steel gradient porous materials by a selective laser melting molding technology, the pore diameter of the materials floats from 3um to 100um, and when the materials are used as filter screens for filtering juice, the time and the steps of replacing the filter screens for many times are saved, and the filtering efficiency is greatly improved.

The invention discloses a Ni/Cr/Fe porous material with gradient apertures and a preparation method thereof (application number 201710485610.9). Mixed powder with different particle sizes is tiled layer by layer, pressed, cooled and formed, and then sintered under vacuum and no pressure to obtain the Ni/Cr/Fe porous material with gradient apertures. The process belongs to a particle stacking method, and utilizes the stacking of particles with different particle sizes to form pores with variable sizes, and the prepared porous material has low porosity on the whole.

Therefore, the existing preparation method of the gradient porous material has the disadvantages of relatively complicated process, limited porosity and pore diameter change range of the porous material and high cost. The invention provides a preparation method of organic template dipping forming-pressureless sintering, which is a new process for preparing gradient porous ceramic, wherein the gradient template is simple and easy to obtain, two or more layers of organic templates with different gradient structures can be obtained by matching and connecting organic sponges with different pore diameters, and the gradient structure of the organic template can be perfectly copied into a porous ceramic blank by adopting slurry dipping forming. In the raw materials used by the invention, Ti powder can react with carbon atmosphere in a sintering furnace in the high-temperature sintering process to generate TiC, and Mo powder can promote the sintering of the TiC, so that the porous ceramic material with good mechanical property is obtained. The gradient TiC porous ceramic prepared by the invention has two structures of porous and gradient, has the advantages of high porosity, uniform pore size distribution, adjustable gradient layer matching, tight interlayer combination, high mechanical property and the like, and has wide application prospects in multiple fields of tail gas filtration, noise reduction and noise reduction, so that the application is provided.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing gradient TiC porous ceramic by taking polyurethane sponge as an organic template and TiC powder, Ti powder, Mo powder and the like as raw materials.

In order to solve the technical problems, the technical scheme adopted by the invention is to provide an organic template dipping forming-pressureless sintering process method for preparing gradient TiC porous ceramic, which comprises the following steps:

1) pretreating polyurethane sponge with different pore diameters;

2) compounding the pretreated sponges with different apertures to obtain a gradient organic template;

3) weighing a certain amount of TiC powder, Ti powder, Mo powder, deionized water and PVB (polyvinyl butyral), and preparing slurry by ball milling and mixing;

4) putting the organic template prepared in the step 2) into the slurry prepared in the step 3) for dipping, and drying to obtain a gradient TiC porous ceramic blank;

5) and 4) sintering the blank obtained in the step 4) in a furnace to obtain the gradient TiC porous ceramic.

Preferably, the pore size of the polyurethane sponge in the step 1) is 15PPI (Pores Per Inc) to 90 PPI; the sponge pretreatment method comprises the following steps: soaking sponge in 10% NaOH solution for 6-24 h, and then placing the sponge in CMC (sodium carboxymethylcellulose) solution for 12-36 h.

Preferably, the method for preparing the gradient organic template in the step 2) comprises the following steps: the polyurethane sponges with different pore diameters are combined together in the modes of sewing, glue bonding, resin bonding and the like.

Preferably, the slurry in step 3) contains the following raw materials in percentage by mass: 18-40 wt% of TiC powder, 9-20 wt% of Ti powder, 3-5 wt% of Mo powder, 3-10 wt% of PVB and the balance of deionized water; the ball milling method is roller ball milling, the ball-material ratio is 2:1, and the ball milling time is 12-24 hours.

Preferably, the impregnation process in step 4) is as follows: and (3) completely immersing the organic template into the slurry, taking out the organic template, discharging redundant slurry in an extrusion or centrifugal rotation mode, repeating the steps for 3-5 times, and heating and drying at room temperature or in an oven to obtain a gradient TiC porous ceramic blank.

Preferably, the sintering process conditions in step 5) are as follows: the sintering temperature is 1600-1800 ℃, and the temperature is kept for 0.5-3 hours under the protection of vacuum or inert gas.

The invention has the beneficial effects that: the gradient TiC porous ceramic prepared by the method has the advantages of high porosity, uniform pore size distribution, adjustable gradient layer matching, tight interlayer combination, excellent mechanical property, low production cost and the like, and can meet the application requirements of various working conditions.

Drawings

FIG. 1 is a sample of a gradient TiC porous ceramic prepared by the organic template dip forming-pressureless sintering process in example 1;

FIG. 2 is a surface micro-topography of the gradient TiC porous ceramic prepared in example 1 using an organic template dip forming-pressureless sintering process;

FIG. 3 is a microscopic morphology of high-power fracture of the gradient TiC porous ceramic prepared by the organic template dip-forming-pressureless sintering process in example 1.

Detailed Description

The invention is further described with reference to the following figures and examples.