ES2341417B1 - POROUS MICROSTRUCTURE WITH INTERCONNECTED CHANNELS OF PERFECTLY DEFINED GEOMETRY AND EQUIPPED WITH MECHANICAL STABILITY AT HIGH TEMPERATURES. - Google Patents

Abstract

Porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures.

It involves the preparation of a material with interconnected channels of perfectly defined geometry that They have mechanical stability at high temperatures.

The perfect hollow channels through it are obtained using a combination of a polymer mesh organic, solvents, plasticizers and powder of material a mold. The incorporation of porous channels through materials inorganic allows to easily drive combustible gases and / or gases of oxidation, in addition to facilitating the infiltration of said channels with other substances such as catalysts, interconnectors, biomaterials, etc.

Description

Porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures.

Technical sector

Chemical engineering. Ceramic sector.

Introduction

The need to incorporate porous channels, to through inorganic materials used in fuel cells, to be able to properly drive the fuel gases and oxidizers make it necessary to create an adequate method of manufacture of materials for high temperatures, up to 1400ºC for 5 to 10 hours, to maintain the porosity conditions necessary and not to agglomerate.

It provides a method that allows to solve this problem in fuel cells, however it can be applied in other fields such as bioengineering. The proposed method allows to create porous materials compatible with the bones of the human body that can be used as grafts. Additionally this porosity allows them to be impregnated with medications to help heal wounds, promote bone growth or avoid losses by descaling.

At the same time, in the field of cars, Catalysts for the vehicle's exhaust are usually Very porous structures to absorb a large amount of gases. He proposed method allows the generation of very porous structures in the desired way and economically.

The procedure described in this document It can be applied in any field where you want to create controlled porosity, in the form of tunnels, and at elevated temperatures So in fuel cells, when used interconnects, these must have printed channels for Where the gases circulate Very expensive methods are generally used of machining to obtain said channels, with this method it would be possible to obtain it at a very low cost.

Also within the field of batteries fuel, platinum or gold meshes are usually used as current collectors These meshes are expensive, so if we could lighten the precious metal content would be much more interesting. This method allows to paint the meshes or immerse it in a dispersion of the precious metal and then by subsequent burned at 800 ° C, a metallic but hollow mesh would be obtained. With what that we would achieve the desired objective, that is, a micro material structured flat, tubular, three-dimensional, etc. porous with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures.

State of the art

The invention object of this application refers to to the process of manufacturing the porous material with channels interconnected, to the material manufactured by said procedure and to the possible uses of said material in cell applications of fuel, catalysts, biomaterials, etc.

Several documents are known that are refer to the manufacture of porous ceramic elements with channels interconnected

In particular JP61192347 refers to a support three-dimensional ceramic for catalysts. To this end a ceramic catalyst support suspension (gamma-Al2O3) with which a form is impregnated three-dimensional polyurethane which is then calcined at 1,000-1,300 ° C to burn organic matter. He result is impregnated with a solution of catalyst salts (RhCl3 or H2PtCl2).

On the other hand, FZF Zhou et al . (Journal of Power Sources 133 (2004) 181-187, "Direct oxidation of jet fuels and Pennsylvania crude oil in a solid oxide fuel cell") refers to a SOFC solid oxide fuel cell of Cu-CeO2 in which Directly combustion of jet fuel and crude oil. The fuel cell consists of a cathode, a dense electrolyte and a porous anode, which is formed by partially mixing polymethylmethacrylate, as a porosity precursor, together with YSZ and then subject it to a severe calcination at 1550 ° C for 4 hours. The result was coated with LSM (0.8 Sr 0.2 MnO3) to calcine again at 1250 ° C for 2 hours.

However, unlike what is proposed in said disclosures, the presence of interconnected channels in the Porous material of the invention provides the advantage of avoiding collapse of the ordered microstructure and the consequent decrease of the available surface of the microporous material.

The disclosures in which they are used polymeric materials for forming materials microporous for fuel cell oriented purposes, catalysts and other applications do not reveal the use of commercial meshes of polymeric materials as a support for Preparation of such materials. In addition, in our invention, after calcination, the mesh of polymeric material provides channels interconnected whose presence decreases the collapse of porosity and avoid, a quantitative decrease in the active surface of the material, which is an advantage over disclosures mentioned.

Description of the invention

It involves the preparation of material with interconnected channels of perfectly defined geometry that it has mechanical stability (that is, it does not collapse) at high temperatures

The perfect hollow channels through it are obtained using a combination of a mesh (polymer organic), solvents, plasticizers and powder of material a mold. The incorporation of porous channels through materials inorganic allows to easily drive combustible gases and / or gases of oxidation, in addition to facilitating the infiltration of said channels with other substances such as catalysts for vehicles, interconnectors in fuel cells, biomaterials, etc.

The procedure is also developed for create, at high temperatures (above 1400ºC) the channels interconnected porous consisting of the following stages:

First: coating a commercial mesh of polymeric material (for example polyester) that is impregnated or covers with a suspension of precursors of ceramic materials in which may also be other porosity generating materials and suspension stabilizers (plasticizers, solvents, dispersants, etc.).

Second: drying the impregnated mesh for subsequent conformation by cutting, stretching, rolling, etc.

Third: calcination by heating mild to temperatures above 600 ° C to eliminate organic material that constitutes the mesh, leaving the channels that originally occupied.

Fourth: submits to the material resulting from the previous calcination at a higher sintering end temperature at 800 ° C (for example between 1200 and 1400 ° C).

Fifth: After sintering, you get the Ceramic material resulting object of our request.

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In more detail you have:

First: a commercial organic mesh is used (a polyester), its shape is perfectly neat, square, hexagonal, pentagonal, rhomboid, etc. This mesh of material organic, being plastic, can be cut or molded very easily, without the need for sophisticated means.

Second: one is prepared next dispersion of the material we want to mold (in our case it is usually ceramic) and a series of organic elements additional or additives (plasticizers, solvents, dispersants). Additives basically allow our material to have a viscous appearance, that dries relatively quickly and that at the end of This process you get a plastic texture. When you get one plastic structure subsequent modeling is simplified, no need of specific equipment as indicated above.

Third: We impregnate the mesh obtained in the First stage in the mixture prepared in the second stage. This shape our mesh will be easily covered by a thin layer mix. When drying we will have the mesh covered with the material, and both will be plastic, so they can easily be cut, warp, stretch, curl etc.

Fourth: Removing the mesh from the material, it they will create the channels at the location where the polymer mesh. For this, it is gently heated to temperatures of 600 ° C onwards. Normally at high temperatures the porosity of any material usually collapses, but with this method you get keep the porosity (or channels) intact even at 1400º, the mesh used allows to control both the geometry and interconnection of the channels as the geometric form of the final material, that is, We can manufacture a cylindrical, cubic sample, etc. This has not been managed to get at high temperatures.

Description of the figures

They exclusively illustrate the creation process of a tubular design.

Step 1. We initially have a mesh impregnated (a) and a small alumina tube (b) with a groove (C).

Step 2. One end of the mesh (a) is inserted into the slot (c).

Step 3. The tube (b) is turned until rolled totally on itself the mesh (a).

Step 4. The tube (b) is inserted with the mesh rolled, inside another alumina tube (d).

Step 5. The tube (b) is removed leaving the mesh inside (d) as shown in Figure (6).

Step 6. Resulting from the prepared preparation for calcination.

Embodiments of the invention

Two examples of realization of the invention.

Example 1 Flat design example

The following sequence is followed:

First: A piece of polyester mesh is cut commercial opening mesh 120 microns, and it is shaped circular, being able to choose others, square, triangular, hexagonal, etc. In this case a circular fragment with 1 cm of diameter.

Second: The dispersion of the material to mold. In this case a YSZ compound will be used. For 10 g. The following materials are weighed from YSZ: 8 g of one solvent dissolution of Methyl ethyl ketone and ethanol that are in a relationship (3: 2); 0.5 g of Triton-Q (dispersant); 0.75 g of PEG400 (plasticizer); 0.75 g of Dibutylphthalate (plasticizer) and 1 g of Butvar (binder or binder) All these elements are mixed in a suitable container and a milling is done (ball-milling), during 2 hours at 150 rpm.

Third: Next the mesh is impregnated circular obtained in the first stage with the mixture obtained in the second. It is only necessary to submerge it completely and take it out slowly. Due to the proportion of solvents used, the mesh impregnated dries in just a few minutes after which Can manipulate by hand without any problem.

Fourth: The impregnated mesh is left on top of a piece of alumina that supports us to introduce our It shows in the oven. It is heated at 2 ° C / min to 600 ° C, and then It can heat at 5ºC / min until 1400º, where we leave it for 5 hours. And with this the final process claimed will end.

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Example 2 Tubular Design Example

First: In this case we take a piece rectangular mesh mesh 120 mesh opening microns, dimensions 30 mm wide x 40 mm deep.

Second: The dispersion is prepared exactly same as in the second stage of the previous example.

Third: It is impregnated exactly as in the third stage of the previous example.

Fourth: What changes in preparation of a flat design is the procedure to give the tubular shape to the impregnated mesh. For this a small alumina tube is used 2.4 mm thick and 10 cm long, to which a small slot of a few tenths of a millimeter thick and long equal to the width of the mesh to use.

The impregnated mesh resulting from the stage third, it snaps into the groove of the tube (b) and turning on itself said tube itself is rolled around it, giving it a tubular shape

Then we insert this small tube rolled inside another 6mm diameter alumina tube inside. Removing the tube (b) that served as support. The Mesh, being flexible, will extend towards the walls of the tube (d). Subsequently we submit the tube (d) with the mesh inside to 1200ºC, with a ramp of 5ºC / min. After cooling, the molded material inside the tube (d) without problem since during heating there is a small contraction of the material housed in the tube (d).

Fifth: Finally to provide greater mechanical stability we heat the resulting YSZ material, since molded, at 1400ºC 5 hours, with a ramp of 5 ° C / min, so that it has the definitive porous tubular material with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures.

Claims (10)

1. Procedure for obtaining a porous microstructure with interconnected channels of perfectly defined geometry and equipped with mechanical stability at high temperatures characterized by the following stages:

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First: The use of a commercial mesh polymeric

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Second: The preparation of a dispersion of material to be molded together with additional additives such as plasticizers, solvents, dispersants, etc.

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Third: The impregnation of the mesh obtained in the First stage in the preparation obtained in the second stage. One time to dry, the first stage mesh will be covered by the Second stage material.

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Fourth: The removal of the stage mesh first of the organic compound of the second stage that has impregnated in the third stage is removed by gently heating temperatures above 600 ° C.

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2. Procedure for obtaining a porous tubular microstructure with interconnected channels of perfectly defined geometry and equipped with mechanical stability at high temperatures characterized by the following stages:

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First: The use of a commercial mesh polymeric

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Second: The preparation of a dispersion of material to be molded together with additional additives such as plasticizers, solvents, dispersants, etc.

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Third: The impregnation of the mesh obtained in the First stage in the preparation obtained in the second stage. One time to dry, the first stage mesh will be covered by the Second stage material.

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Fourth: The winding of the stage result third in a tube (b) to which a small groove is applied and of length equal to the width of the mesh to be used (c).

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Fifth: Insertion of the tube (b) with the mesh impregnated and rolled, resulting from the fourth stage, in a tube (d) larger than the previous diameter.

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Sixth: Extraction of the tube (b) allows the Impregnated and rolled mesh, being flexible, extends to the tube walls (d).

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Seventh: Heating the tube (b) with the mesh impregnated and rolled inside at a temperature higher than 1000 ° C

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Eighth: After cooling the material separates molded inside the tube (d).

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Ninth: Optional final heating to provide greater mechanical stability to the resulting material at a temperature higher than the one used in the seventh stage.

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3. Porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures obtained according to the procedure of claim 1. 4. Porous tubular microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures obtained according to the procedure of claim 2. 5. Use of porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures according to claim 3 for bone grafts due to its high porosity. 6. Use of porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures according to claim 3 for vehicle catalysts. 7. Use of the porous tubular microstructure with interconnected channels of perfectly defined and endowed geometry of mechanical stability at high temperatures obtained according to the claim 3 for electrodes, interconnects or collectors of current in fuel cells and also in the electrolyte of fuel cells 8. Use of the porous tubular microstructure with interconnected channels of perfectly defined and endowed geometry of mechanical stability at high temperatures according to claim 4 for biomaterials such as bone grafts due to its high porosity. 9. Use of the porous tubular microstructure with interconnected channels of perfectly defined and endowed geometry of mechanical stability at high temperatures according to claim 4 Used in vehicle catalysts. 10. Use of porous microstructure with channels interconnects of perfectly defined geometry and equipped with mechanical stability at high temperatures according to claim 4 for electrodes, interconnects or current collectors in batteries of fuel and also in the battery electrolyte of fuel.