Patent Application
20090162635
The present invention relates to a composite porous metal body preferable for filters, gas diffusion members, heat-radiating elements, water-absorbing members and the like, and a method for manufacturing the same.
Porous metal bodies are applicable to various kinds of use, such as for filters, gas diffusion members, heat-radiating members, and water-absorbing members, and are provided in various apparatuses. However, since these types of porous metal bodies generally have disadvantageous properties such as low strength and susceptibility to deformation, problems are known in difficulties in handling of the porous metal bodies.
For preventing damage to a porous body which occurs when the porous body as a filter element is incorporated into a filter apparatus, a technique has been proposed in which a dissimilar material is filled into an end area of a filter element to reinforce the filter element, for example, as disclosed in Japanese Unexamined Patent Application, First Publication No. Sho 48-13956.
Further, for providing holes for securing a metal foam to an apparatus, a technique has been proposed in which a solid such as metal or plastic is filled into fine pores of the porous metal body to provide the porous metal body with a portion with increased strength, for example, as disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 08-53723.
However, in a case where a surface of a porous body is covered with a resin or the like to improve the strength of the porous body, when it is desired to provide a securing hole in a reinforced portion of the porous body, it becomes necessary to simultaneously cut out the resin and the metal, so that processing and shaping of the porous body becomes difficult.
Further, a porous metal body is generally difficult to produce, and is expensive. Therefore, it is desired to utilize a porous body without waste and to fully exhibit the properties thereof. However, reinforcing a porous body by covering a surface thereof with a resin or a metal reduces the effective area of the porous body, and results in an increase in cost.
The present invention addresses the circumstances described above, with an object to improve handling properties of a porous metal body without sacrificing the effective area thereof.
The present invention solves the above-mentioned problems and achieves the above-mentioned objects by a composite porous metal body including a sheet-like metal part containing a porous body having a three-dimensional network structure and being made of titanium or titanium alloy, and a resin part extending in an in-plane direction of the metal part and being integrally formed with the metal part.
Further, a method for manufacturing a composite porous metal body of the present invention includes performing insert-molding by using the metal part as an insert and injecting the resin part so as to be connected to an edge of the metal part.
By the composite porous metal body of the present invention, a resin part can be provided on the edge of the metal part having low strength, thereby rendering it possible to realize a porous metal body exhibiting excellent handling properties. Further, since the resin part extends to protrude from the metal part, it becomes possible to process only the resin part, so that various shapes such as holes or the like for securing to an apparatus can be easily provided.
The place for providing the resin part is not limited to the entire periphery or outer periphery of the metal part, and can be partially provided, if desired. Further, the porous metal body may have a structure in which a plurality of metal parts is connected by resin parts. Furthermore, resins for the resin part are not limited to synthesized resins, and includes rubber materials such as elastomers.
In addition, by the method for manufacturing the composite porous metal body of the present invention, since molten resin enters pores opened to the side portion of the metal part where the metal part is connected to the resin part, and is solidified in the pores, it becomes possible to produce a composite porous metal body in which the metal part and the resin part are securely connected to each other by an anchoring effect.
With respect to the portion where the metal part is connected to the resin part (hereafter, frequently referred to as “connected portion”), due to the three-dimensional structure of the metal part, the depth of the resin part entering the metal part becomes heterogeneous on the entire outer periphery of the metal part, and the connected portion has small spaces forming a complicated structure. When a portion where the skeleton constituting the three-dimensional structure of the metal part is connected to the resin part is observed with magnification, it can be seen that spaces are formed where the skeleton of the metal part is not in contact with the resin part. Thus, the connected portion has a structure in which a multitude of small spaces are observed microscopically. When a composite porous metal body is placed in air or a corrosive gas such as chlorine gas, or when such gas or moisture passes through the metal part, since diffusion of a substance is difficult in the connected portion, difference in level of concentration of oxygen ions and corrosive ions is generated, thereby generating potential difference in the skeleton which acts as a local cell. Therefore, crevice corrosion occurs in the connected portion of the metal part, so that the resin part may be released from the metal part.
However, in the composite porous metal body of the present invention, since the metal part is constituted from titanium or titanium alloy, it becomes possible to suppress the occurrence of crevice corrosion more certainly than in the case of stainless steel. Therefore, in the composite porous metal body of the present invention, it becomes possible to improve the corrosion resistance of the metal part, regardless of the service condition, and a satisfactory connection of the metal part and the resin part can be maintained over a long period.
Titanium constituting the metal part means a material containing 98.0 wt % or more of titanium. Titanium alloy means a material containing less than 98.0 wt % of titanium, such as Ti-6Al-4V or Ti-10V-2Fe-3Al.
Hereinbelow, various embodiments of the present invention will be described with reference to the figures.
As shown in
The metal part 11 is a rectangular thin plate having a three-dimensional network structure. The metal part 11 exhibits air permeability and a water absorption property by virtue of mutual communication between laterally opened pores in various directions, and is characterized in that it has a light weight and a large surface area. The metal part 1 is made of titanium or titanium alloy. More specifically, the metal part 11 is made of a material containing 98.0 wt % or more of titanium, or a material containing less than 98.0 wt % of titanium such as Ti-6Al-4V or Ti-10V-2Fe-3Al.
The resin part 12 is formed in the shape of a thin plate connected to an outer peripheral edge of the metal part 11, and is formed with almost the same thickness as the metal part 11 without any height difference therebetween.
The composite porous metal body 10 in which the metal part 11 and the resin part 12 are integrally formed constitutes a single thin-plate member as a whole, and may be attached to various apparatuses by, for example, fixing or sandwiching the resin part 12 so as to be used as filters, water-absorbing members, or heat-radiating elements, and the like.
With respect to the portion where the metal part 11 is connected to the resin part 12 (hereafter, frequently referred to as “connected portion”), due to the three-dimensional structure of the metal part 11, the depth of the resin part 12 entering the metal part 11 becomes uneven on the entire outer periphery of the metal part 11, and the connected portion has small spaces forming a complicated structure. When a portion where the skeleton 11a constituting the three-dimensional structure of the metal part 11 is connected to the resin part 12 is observed with magnification as shown in
Next, the method for manufacturing a composite porous metal body 10 having a constitution as mentioned above will be described. Firstly, a method for producing the metal part 11 which is a porous metal body will be described with reference to
The slurry S is obtained by mixing together a metal powder such as a titanium powder which has been subjected to hydrogenation and pulverization or a titanium alloy powder obtained by gas atomization, an organic binder (for example, methyl cellulose or hydroxypropylmethyl cellulose), a solvent (water), and, optionally, a foaming agent (for example, nonaqueous hydrocarbon-based organic solvent with five to eight carbons (e.g., neo-pentane, hexane, and heptane)) that is evaporated or sublimated by heating treatment or a defoaming agent (e.g., ethanol).
In the green-sheet manufacturing apparatus 30, the slurry S is stored in a hopper 31. Then, the slurry S is supplied from the hopper 31 onto a carrier sheet 33 to be conveyed by rollers 32. The slurry S on the carrier sheet 33 is extended between the moving carrier sheet 33 and a doctor blade 34 so as to be formed with a required thickness. The molded slurry S is further conveyed by the carrier sheet 33 to pass through a heating furnace 35. Then, the slurry is dried in the heating furnace 35 to form a green sheet G in which the metal powder is joined by an organic binder.
When a foaming agent is contained in the slurry S, the slurry S extended on the carrier sheet 33 is subjected to heating treatment in a high humidity atmosphere and then foamed by a foaming agent to obtain a foamed slurry, before it is dried. Then, the foamed slurry is subjected to drying treatment, thereby forming a green sheet G.
After the green sheet G is detached from the carrier sheet 33, it is degreased and calcinated in a vacuum furnace (not shown) whereby the organic binder is removed to form a porous metal body (metal part 11) in which the metal powder particles are sintered together. The organic binder contains carbon which sometimes cannot be removed by the calcination. Therefore, the metal part 11 inevitably contains carbon. Specifically, the metal part 11 may inevitably contain 0.6 wt % or less of carbon.
Next, a method for manufacturing a composite porous metal body 10 from the thus produced metal part 11 will be described with reference to
The metal part 11 as an insert part is disposed in a cavity 22 defined between a pair of molds 20 and 21, and a molten resin 25 injected through a gate 24 from a runner 23 is then filled in the cavity 22. Then, the molten resin 25 is cooled and solidified, thereby forming a composite porous metal body 10 in which the metal part 11 and the resin part 12 are integrated into one body. When the composite porous metal body 10 is formed by insert molding, the thickness of the cavity 22 (the size of the cavity in a direction in which molds are opened or closed) at the time when the molds are closed is slightly smaller than that of the metal part 11. Specifically, when the metal part 11 is compressed up to 3 to 90% between the molds 20 and 21 at the time when the molds are closed, even when the injection pressure of the molten resin 25 is applied to the metal part 11, it is possible not only to suppress positional deviation of the metal part 11 in the cavity 22, but also to improve the flatness of a surface of the metal part 11.
In manufacturing a composite porous metal body by insert molding in a manner as described above, in the case where the pore diameter of the metal part 11 is in the range of 10 μm to 2 mm and the porosity thereof is in the range of 40 to 98%, and the resin part 12 is made of polypropylene, when the insert injection molding was performed under conditions wherein the mold temperature was 180° C., the mold clamping force was 80 kN, and the injection pressure was 25 MPa, it was confirmed that the molten resin 25 impregnated and solidified in pores opened to a side portion of the metal part 11 to a depth of 5 to 1,000 μm (anchoring effect), and that the composite porous metal body is not deformed by the molding pressure of the molten resin 25 or the shrinking behavior at the time of cooling and solidifying.
When the pore diameter or porosity of the metal part 11 is too small, there is a possibility that the molten resin cannot enter the pores to exhibit a satisfactory anchoring effect, so that a satisfactory joining strength with resin part 12 cannot be obtained. On the other hand, when the pore diameter or the porosity of metal part 11 is too large, there is a possibility that the strength of the metal part becomes unsatisfactory, so that the composite porous metal body cannot sustain the molding pressure of the resin part 25 or the shrinking behavior at the time of cooling and solidifying, thereby suffering deformation.
The material for the resin part 12 is not limited to polypropylene, so long as it is a material which can be subjected to injection molding, such as a thermoplastic resin or an elastomer. Therefore, the material for the resin part 12 may be appropriately selected depending on use, taking into consideration heat resistance temperature and hardness. Further, the resin part 12 may be flat as shown in
As mentioned above, the portion where the metal part 11 is connected to the resin part 12 (hereafter, frequently referred to as “connected portion”) has a structure in which a multitude of small spaces 10a are observed microscopically. Therefore, as described below, when a composite porous metal body 10 is placed in air or a corrosive gas such as chlorine gas, or when such gas or moisture passes through the metal part 11, since diffusion of a substance is difficult in the connected portion, a difference in the level of concentration of oxygen ions and corrosive ions is generated, thereby generating potential difference in the skeleton 11a which acts as a local cell. Therefore, crevice corrosion occurs in the connected portion of the metal part 11, so that the resin part 12 may be released from the metal part 11.
However, in the composite porous metal body 10 according to the present invention, since the metal part 11 is made of titanium or titanium alloy, it becomes possible to suppress the occurrence of crevice corrosion more certainly than in the case of stainless steel. Therefore, in the composite porous metal body 10 according to the present invention, it becomes possible to improve the corrosion resistance of the metal part 11, regardless of the service condition, and a satisfactory connection of the metal part 11 and the resin part 12 can be maintained over a long period.
The thus manufactured composite porous metal body 10 may be used in the following applications.
The filter unit 41 has a structure in which a plurality of filters 40 is inserted in a filter box 42 made of a resin or a metal, and a top member 43 is attached to the filter box.
In the filter unit 41, by constituting the resin part 12 of the filter 40 with an elastic member such as an elastomer, the filter box 42 and the top member 43 can be secured air-tightly, so that a fluid to be filtered may be passed through the metal part 11 without leakage. Further, by producing the metal part 11 so as to carry a photocatalyst such as titanium oxide, gaseous contaminants captured by the filter may be decomposed by light irradiation, thereby enhancing air purification.
In the packed column 51, the composite porous metal body 10 as a packing-support plate 50 is secured to shell 52, for example, by securing the resin part 12 provided with screw holes, and the metal part 11 supports the filler while allowing the liquid and the gas to pass therethrough.
In the water absorbing member 60, the resin part 12 functions as a part for securing the composite porous metal body 10. Therefore, when the metal part 11 is not strongly required to have high strength, the resin part 12 need not be provided around the entire periphery of the metal part 11, and may be provided on one edge of the rectangular metal part 11.
Since the electrode 70 and the filter 71 can be secured to the apparatus on the resin part 12, insulation can easily be achieved by forming the resin part 12 with an electrically insulative material, so that the constitution of the apparatus can be simplified. Further, for connecting the electrode 70 with a power supply at the metal part 11, the resin part 12 may be made of a conductive resin, or a metal interconnect may be printed on a surface of the resin part 12.
As shown in
The fuel supply part 98 for supplying fuel to the fuel electrode 91 has a structure in which a porous part 99 holding and supplying fuel by capillary action is provided with a resin part 100 around the outer periphery thereof for sealing. The fuel supply part 98 and the fuel electrode 91 are secured to each other by, for example, ultrasonic joining of the resin part 100 of the fuel supply part 98 with the resin part 12 of the fuel electrode 91.
Alternatively, composite porous metal bodies 10 according to the present invention may be used for gas diffusion electrodes 110 in a fuel cell having a structure as shown in
In the gas diffusion electrode 110 (10), a plurality of metal parts 11 is arranged in an in-plane direction with intervals, and the resin part 12 is provided so as to fill up the intervals between the metal parts 11 and to surround the entire periphery of the metal portions 11. Each of the metal parts 11 has a catalyst layer (not shown) formed on a surface thereof. The fuel cell has a constitution in which an electrolyte layer 111 is sandwiched between two gas diffusion electrodes 110, so that the catalyst layers of each of the gas diffusion electrodes 110 face the electrolyte layer 111, and the respective metal parts 11 are directly connected in a sequential manner.
In the constitution shown in
On the other hand, in the constitution shown in
By employing a constitution in which a connecting member 112 or 113 is used to connect metal part 11, there is no need for providing other members, such as thin metal tabs 92 as shown in
Further, composite porous metal bodies 10 according to the present invention can be used for gas diffusion electrodes of a stacked-type polymer electrolyte fuel cell (
Each of
The electrolyte layers 121 are provided with through holes which communicate with the through holes of the gas diffusion electrode 120. More specifically, the electrolyte layers 121 are provided with through holes 121a which communicate with the communicating holes 120a and 120b and through holes 120c and 120d of the gas diffusion electrode, and bolt insertions holes (not shown) which communicate with the bolt insertion holes 120e.
Further, the separator plates 122 are also provided with through holes that communicate with the through holes of the gas diffusion electrode 120. More specifically, the separator plates 122 are provided with through holes 122a which communicate with the communicating holes 120a and 120b and through holes 120c and 120d of the gas diffusion electrode, and bolt insertions holes (not shown) which communicate with the bolt insertion holes 120e.
The gas diffusion electrodes 120, the electrolyte layers 121 and the separator plates 122 stacked together can be integrally fixed together by inserting bolts through the bolt insertion holes and fixing the bolts with nuts.
The two gas diffusion electrodes 120 which are stacked by sandwiching the electrolyte layer 121 are arranged so that the front and the back are reversed, and one serves as a fuel electrode 120A, while the other serves as an air electrode 120B.
More specifically, the communicating hole 120a of the fuel electrode 120A communicates with through hole 120d of the air electrode 120B, and the communicating hole 120b of the fuel electrode 120A communicates with the through hole 120c of the air electrode 120B, thereby forming a fuel supplying channel F1 and a fuel discharging channel F2 respectively extending in the thicknesswise direction of the fuel cell (i.e., crosswise direction in
Similarly, the communicating hole 120c of the fuel electrode 120A communicates with through hole 120b of the air electrode 120B to form an air supplying channel (not shown) extending in the thicknesswise direction of the fuel cell, and the communicating hole 120d of the fuel electrode 120A communicates with the through hole 120a of the air electrode 120B to form an air discharging channel (not shown) extending in the thicknesswise direction of the fuel cell (i.e., crosswise direction in
Thus, in the fuel cell of the present embodiment, a single cell is constituted by sandwiching an electrolyte layer 121 between two gas diffusion electrodes 120, and covering both sides with separator plates 122. Further, by arranging a fuel electrode 120A and an air electrode 120B via a separator plate 122, a constitution can be obtained in which the fuel electrode 120A and the air electrode 120B are air-tightly separated, and an exchange of electrons can be performed through the separator plate 122, thereby rendering it possible to constitute a fuel cell in which a plurality of cells are connected in series.
Each of the constituent members, the shapes thereof and combinations thereof in the embodiments described hereinabove are merely examples, and may be modified depending on required design without departing from the scope of the present invention. For example, although a metal part 11 is produced from a green sheet G in the aforementioned embodiment, there is no restriction, and the metal part 11 may be produced from a nonwoven metal fabric.
The present invention provides a composite porous metal body in which the handling property thereof is improved while maintaining the effective area thereof, and a method for manufacturing the same.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-335079 | Nov 2004 | JP | national |
This is a U.S. national phase application under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2005/020800 filed Nov. 14, 2005, and claims the benefit of Japanese Application No. 2004-335079 filed Nov. 18, 2004, both of them are incorporated by reference herein. The International Application was published in Japanese on May 26, 2006 as International Publication No. WO/2006/054504 under PCT Article 21(2).
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2005/020800 | 11/14/2005 | WO | 00 | 5/17/2007 |
