JP5115942B2 - Piping for fuel cell and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe used in a fuel cell, particularly a polymer electrolyte fuel cell system, and a method for manufacturing the same.
[0002]
[Prior art]
Fuel cells are being developed as part of countermeasures against energy problems associated with global warming, air pollution caused by harmful substances, or a decrease in fossil fuel reserves. In particular, fuel cell vehicles are required not only to meet strict driving conditions but also to improve economy and efficiency.
Solid polymer fuel cells, which are regarded as the most promising for automotive use, react hydrogen and oxygen and take out the electrical energy generated at that time. The electrode is an ion exchange membrane that selectively permeates hydrogen ions. And hydrogen is supplied to the negative electrode side and oxygen is supplied to the positive electrode side. Since this ion exchange membrane is generally formed of a very thin membrane of about 50 to 200 μm, it is not only easily broken by foreign matter in the piping system, but also iron, copper, and aluminum that hinder the catalytic reaction in the electrode. Therefore, there is a need for a clean state in which there is very little foreign matter remaining in the piping and no ions that impair the catalytic reaction remain. .
[0003]
This fuel cell piping uses austenitic stainless steel such as SUS304 or SUS316, and uses expensive piping material that has been washed with ultrapure water after being pickled or electrolytically polished to clean the inner surface. Has been. In addition, pipe joints such as flares and parts subjected to plastic working such as bending parts are cleaned to avoid stress corrosion due to residual stress, and the inner surface is cleaned without molding or bending the connecting pipe end parts. A large number of expensive joint parts and the like are combined and connected to form a pipe. Furthermore, these pipe materials are designed so that no heat is applied in order to avoid the progress of corrosion of the sensitized portion due to the thermal effect during welding. Such fuel cell pipes are generally cut, terminal-molded, perforated, bent, etc., and cleaned by equipment exclusively for stainless steel pipes (no other materials such as iron are processed) A piping system is manufactured by assembling joint parts and the like that have been cleaned in advance.
[0004]
[Problems to be solved by the invention]
However, the conventional method of manufacturing fuel cell pipes using dedicated equipment for stainless steel pipes is not only restricted by pipe design and manufacturing, but also has a problem that the price of the piping system becomes very expensive.
The present invention has been made in order to solve such a conventional problem, and the inner surface is clean and does not cause the residual or generation of harmful ions which hinder the catalytic reaction, and further causes stress corrosion. For fuel cells that can be provided at low cost by pipes for fuel cells with good quality without any sensitized structures and pipes for fuel cells with good quality using ordinary pipe manufacturing equipment such as steel pipes other than dedicated equipment for stainless steel pipes It aims at proposing the manufacturing method of piping.
[0005]
[Means for Solving the Problems]
Piping for a fuel cell according to the present invention, the cutting step, forming step, perforation step, Ri by the production line consisting of a tacking step, any necessary steps for brazing, solid solution heat treatment step and the inner surface cleaning treatment step a manufacturing is the pipe for a fuel cell made of stainless steel, after facilities the cleaning process of dissolving and removing the metal powder adhering to at least the inner surface of the tube including the end face in the inner surface cleaning process step, chemical Ni plating process in by applying at least inner surface to chemical Ni plating including an end face, it is characterized in that to prevent the formation of metal ion to at least inner surface including the end face.
A method of manufacturing a piping the fuel cell, the cutting step, forming step, perforation step, tacking step, the production line consisting of either necessary steps and inner surface cleaning treatment step of brazing, solid solution heat treatment step I in squirrel stainless method of making a fuel cell pipe made of steel, after being subjected to cleaning treatment for dissolving and removing the metal powder adhering to at least the inner surface of the tube including the end face in the inner surface cleaning process step, chemical Ni plating In the process, at least the inner surface of the tube including the end surface is subjected to chemical Ni plating.
In the present invention, after terminal molding and bending in the molding step, when attaching the accessory part to the pipe, it is preferable to perform brazing in the solid solution heat treatment step after tack welding , As the brazing means, it is preferable to use a method of brazing nickel in a hydrogen atmosphere or in a vacuum.
Note that the solid solution heat treatment here does not mean that the “solution treatment” described in No. 1611 of JIS B 6905 “Metal Product Heat Treatment Terminology” is completely carried out, but 1000 ° C. during Ni brazing. Chromium carbide in the vicinity of the grain boundary caused by heating in tack welding due to overheating promotes solid solution in the austenite crystal grains, and even if complete quenching is not possible, it resembles the solution-treated structure and is sensitive This refers to the heat treatment for obtaining an unstructured structure.
As the Ni brazing, for example, methods described in JP 2000-219389 A, JP 2000-218390 A, and the like can be used.
[0006]
In the present invention, the reason why the cleaning process for dissolving and removing the metal powder adhering to at least the inner surface of the pipe including the end surface is performed in the inner surface cleaning process is as follows.
When manufacturing fuel cell piping made of stainless steel using ordinary pipe manufacturing equipment such as steel pipes other than dedicated equipment for stainless steel pipes, metal powder other than stainless steel adhering to existing equipment during cutting or bending is applicable. Adhering to the stainless steel pipe, which corrodes and elutes, generates iron ions that are harmful to the catalytic reaction of the fuel cell. On the other hand, a part of the stainless pipe is sensitized by heat generated in the welding or brazing process, and the part is corroded by moisture which is a fluid of the pipe. This not only impairs the function as fuel cell piping, but also impairs the catalytic reaction due to the outflow of iron ions due to corrosion.
The present invention solves such problems, and the inner surface is clean and free from residual ions and generation of harmful ions that hinder the catalytic reaction, and further has no sensitized texture that causes stress corrosion. As a means for producing good stainless steel fuel cell pipes using ordinary pipe manufacturing equipment other than stainless steel pipe dedicated equipment, at least the metal powder adhering to the pipe inner surface including the end face is dissolved and removed in the inner surface cleaning process. A method of performing a cleaning process is adopted. Here, the method of dissolving and removing the metal powder adhering to the inner surface of the tube is not particularly limited, but a method of acid cleaning after degreasing can be used.
[0007]
In the present invention, after the cleaning treatment is performed, at least the inner surface of the tube including the end face is subjected to chemical Ni plating in the chemical Ni plating step. For example, in the cleaning treatment, iron particles and the like remain on the inner peripheral surface. Even if this happens, it is covered and shielded by a chemical Ni plating film, so that iron ions and the like can be reliably prevented from adversely affecting the catalytic reaction.
DETAILED DESCRIPTION OF THE INVENTION
1 to 4 exemplify a fuel cell pipe made of stainless steel according to the present invention. FIG. 1 is a side view showing an example of a fuel cell pipe provided with a spool at a pipe end, and FIG. 3 is a side view showing an example of a fuel cell pipe with a flange attached to the pipe end, FIG. 3 is a side view showing an example of a fuel cell pipe with a bracket attached to the outer surface of the pipe body, and FIG. 4 is a nipple on the pipe body. FIG. 5 is a partially enlarged side view showing an example of another fuel cell pipe with a flange brazed to the pipe end, and FIG. 6 relates to the present invention. FIG. 7 is a manufacturing process diagram showing another embodiment, FIG. 8 is a manufacturing process diagram of the fuel cell pipe shown in FIG. 1, and FIG. FIG. 10 is a manufacturing process diagram of the fuel cell piping shown in FIG. 2, and FIG. 10 is for the fuel cell shown in FIG. Manufacturing process drawing of the tube, FIG. 11 is a manufacturing process drawing of the piping for the fuel cell shown in FIG.
[0009]
A fuel cell pipe 11 made of stainless steel shown in FIG. 1 is obtained by bending a pipe body 11-1 in which a spool 11-2 is formed by bulging at both pipe ends. The fuel cell pipe 12 made of stainless steel shown in FIG. 2 has a fastening flange 12-2 externally fitted to both ends of the pipe body 12-1 that has been bent, and the outer peripheral edge of the fitting portion. The part is Ni brazed after temporary welding and 12-3 is the Ni brazed part. The pipe 13 for a fuel cell made of stainless steel shown in FIG. 3 is subjected to a bending process on a pipe body 13-1 in which a spool 13-2 is formed by a bulging process, and the pipe body 13- subjected to this bending process. A fixing bracket 13-3 is temporarily brazed and welded to Ni on the outer peripheral surface of the curved pipe portion 1 and 13-4 is the Ni brazed portion. A stainless steel fuel cell pipe 14 shown in FIG. 4 has a branch hole 14-1a formed in a bent pipe portion of a pipe body 14-1 that has been bent, and both pipes of the pipe body 14-1. The fastening flange 14-2 is attached to the end, and the nipple 14-3 is temporarily welded to the branch hole 14-1a, and then the fastening flange 14-2 and the nipple 14-3 are simultaneously brazed with Ni. 14-4 and 14-5 are Ni brazing parts.
[0010]
The fuel cell pipe 15 made of stainless steel shown in FIG. 5 has a fastening flange 15-2 formed so as to cover the open end face of the pipe end portion at the pipe end portion of the pipe body 15-1. The outer peripheral edge of the fitting portion is brazed with Ni, and 15-3 is the Ni brazed portion. In the case of this fuel cell pipe 15, the inner surface of the pipe body 15-1 is brazed by filling the gap formed between the flange 15-2 and the pipe body 15-1 with the Ni brazing material 15-4. A material fillet is formed, gaps are eliminated, and crevice corrosion is prevented.
[0011]
In the stainless steel fuel cell pipes 11 to 15 shown in FIGS. 1 to 5 described above, the metal powder is dissolved and removed in the inner surface cleaning process. Therefore, there is no residual or generation of harmful ions that interfere with the catalytic reaction.
[0012]
Next, a method for manufacturing the stainless steel fuel cell pipe shown in FIGS. 6 and 7 will be described.
First, the method for manufacturing a fuel cell pipe made of stainless steel shown in FIG. 6 is a method of manufacturing a fuel cell pipe made of stainless steel in a normal pipe manufacturing facility, and the tube is cut into a predetermined length. Cutting step 21, forming step 22 for performing terminal molding and bending processing on a tube cut to a predetermined length, drilling step 23 for making a hole such as a branch hole, flange or branch pipe at a pipe end or a branch hole, etc. A temporary attachment process 24 for temporarily attaching the parts, a brazing / solid solution heat treatment process 25 for brazing the parts, and an inner surface cleaning treatment process 26 for dissolving and removing at least the metal powder adhering to the inner surface of the pipe including the end face. This is a method of manufacturing stainless steel fuel cell piping in a manufacturing line.
In this method, as a cleaning treatment means for dissolving and removing metal powder adhering to at least the inner surface of the tube including the end surface, a method of acid cleaning after degreasing can be used. In this case, degreasing is performed by immersing in methylene chloride for several minutes at room temperature, and acid cleaning is performed using, for example, 15 v / v% HNO ₃ aqueous solution (67 w / w% HNO ₃ used) +5 v / v% HF aqueous solution (46 w / w% HF used). ), And a method of immersing at 60 ° C. for about 10 minutes can be used.
[0013]
FIG. 7 shows a method for manufacturing a fuel cell pipe made of stainless steel in a manufacturing line in which a chemical Ni plating step 27 for applying chemical Ni plating to at least the inner surface of the pipe including the end face is added to the manufacturing method shown in FIG. This is a method for manufacturing a manufactured fuel cell pipe, and includes the same steps as the manufacturing method shown in FIG. 6 except for the chemical Ni plating step 27.
That is, a cutting step 21 for cutting a tube body to a predetermined length, a forming step 22 for subjecting a tube body cut to a predetermined length to terminal molding or bending, a punching step 23 for opening a hole such as a branch hole, a tube Temporary attaching step 24 for temporarily attaching a part such as a flange or a branch pipe to an end or a branch hole, brazing / solid solution heat treatment step 25 for brazing the part, metal powder adhering to at least the inner surface of the pipe including the end face Manufacturing a stainless steel fuel cell piping in a manufacturing line comprising an inner surface cleaning process step 26 for dissolving and removing, and a chemical Ni plating step 27 for applying nickel plating to the inner and outer surfaces of the tube body from which the metal powder has been dissolved and removed. It is a method to do. As the chemical Ni plating method, electroless nickel plating can be used.
[0014]
In the manufacturing method of the fuel cell pipe shown in FIG. 8, the pipe body is cut into a predetermined length in the cutting step 21, and the spool 11 − 2 and bending, and then, in an inner surface cleaning treatment step 26, the metal powder adhering to at least the inner surface of the tube including the end surface is dissolved and removed.
The fuel cell piping manufacturing method shown in FIG. 9 cuts the tube body to a predetermined length in the cutting step 21, performs bending in the forming step 22, and performs the bending on the tube 12-1. The flanges for fastening 12-2 are externally fitted to both pipe ends in the temporary attachment step 24, and the outer peripheral edge of the fitting portion is attached by temporary attachment, followed by Ni brazing in the brazing / solid solution heat treatment step 25, This is a method of dissolving and removing metal powder adhering to at least the inner surface of the tube including the end surface in the rear inner surface cleaning treatment step 26.
In the manufacturing method of the fuel cell pipe shown in FIG. 10, the pipe body is cut into a predetermined length in the cutting step 21, and the spool 13 − 2, bending is performed, and then a fastening bracket 13-3 is temporarily welded to the outer peripheral surface of the curved pipe portion of the tubular body 13-1 in a temporary attachment step 24, followed by a brazing / solid solution heat treatment step This is a method of brazing Ni at 25 and then dissolving and removing metal powder adhering to at least the inner surface of the tube including the end surface in an inner surface cleaning process step 26.
In the fuel cell piping manufacturing method shown in FIG. 11, the tube body is cut into a predetermined length in the cutting step 21, bent in the forming step 22, and then bent in the drilling step 23. A branch hole 14-1a is formed in the curved pipe portion of the body 14-1, and then a fastening flange 14-2 is externally fitted to both pipe ends of the pipe body 14-1 in the temporary attachment step 24. After the outer peripheral edge portion is tack welded, the Ni brazing is performed in the brazing / solid solution heat treatment step 25, and then the metal powder adhering to at least the pipe inner surface including the end surface is dissolved and removed in the inner surface cleaning treatment step 26. is there.
[0015]
【Example】
Example 1
Using a stainless steel pipe (SUS304 material) having an outer diameter of 38 mmφ × thickness of 1.2 mm, a fuel cell pipe was manufactured using existing steel pipe manufacturing equipment excluding stainless steel pipe dedicated equipment. In this embodiment, a stainless steel pipe cut to a predetermined length is subjected to a terminal bulge process at one end in a forming process, followed by bending the steel pipe using a steel core, and then drilling. After processing (hole diameter 5.5 mmφ), a stainless steel pipe branch pipe (outer diameter 6.35 mmφ, wall thickness 0.5 mm, length 25 mm) is temporarily welded to the hole, and stainless steel is further attached to the pipe end. Tightening welded flange (outer diameter 115mmφ, thickness 12mm) is tack welded, followed by normal nickel brazing and solid solution heat treatment in a hydrogen furnace, degreasing in the final inner surface cleaning process, and acid cleaning The metal powder adhering to the inner surface of the tube including the end face was dissolved and removed. Degreasing is performed by immersing in methylene chloride at room temperature for 3 minutes, and acid cleaning is performed using a 15 v / v% HNO ₃ aqueous solution (67 w / w% HNO ₃ used) + 5 v / v% HF aqueous solution (46 w / w% HF used). And soaking at 60 ° C. for 10 minutes.
Then, the washed stainless steel fuel cell pipe was cut in half in the axial direction, and the salt spray test was conducted for 168 hours, one on the inner surface and the other on the outer surface. The occurrence of red rust (iron rust) was not observed all around the welded part, bending part, branch pipe brazed part, flange brazed part, and temporary welded part for brazing.
[0016]
Example 2
A stainless steel pipe (SUS316 material) with an outer diameter of 16 mmφ × thickness of 1.2 mm is used under the same conditions as in Example 1 (external diameter is 80 mmφ and thickness is 9 mm) with existing steel pipe manufacturing equipment excluding stainless steel pipe dedicated equipment. The fuel cell pipe was manufactured, and the obtained fuel cell pipe was subjected to the same evaluation test as in Example 1 to observe the occurrence of rust. As a result, also in this example, the terminal molded part, the bent part, the branch The occurrence of red rust (iron rust) was not observed all around the pipe brazed part, flange brazed part, and temporary welded part for brazing.
[0017]
Example 3
Using a stainless steel pipe (SUS304 material) with an outer diameter of 38 mmφ and a thickness of 1.2 mm, drilling, terminal bulging, bending, etc. under the same conditions as in Example 1 using existing steel pipe manufacturing equipment excluding stainless steel pipe dedicated equipment After performing temporary welding of branch pipes and flanges, nickel brazing and solid solution heat treatment, alkali degreasing, water washing, pickling are performed to dissolve and remove the metal powder adhering to the pipe inner surface including the end face, and then water washing, Electroless nickel plating was applied to the entire inner and outer surfaces including the branch pipe and the flange, washed with water and dried to produce a fuel cell pipe. The alkaline degreasing in this example was performed by immersing in a normal temperature aqueous solution (Paknal LF612 45 g / l aqueous solution manufactured by Yuken Industry Co., Ltd.) for 3 minutes. All washing was performed by immersing in normal temperature tap water for 3 minutes. The pickling was immersed for 3 minutes in a 10 v / v% hydrochloric acid aqueous solution (using 35 w / w% hydrochloric acid) at room temperature. Electroless nickel plating is performed by immersing in an aqueous solution heated to 90 to 93 ° C. (5-fold diluted aqueous solution of Schimmer S-780-O manufactured by Nippon Kanigen Co., Ltd.) for 15 minutes, and is thick on the entire inner and outer surfaces including branch pipes and flanges. 5 μm thick nickel-phosphorus alloy plating was applied. The drying means used was a method in which moisture was blown away with compressed air (5 kgf / cm ² ). The same evaluation test as in Example 1 was performed on the obtained fuel cell pipe and the state of occurrence of rust was observed. As a result, also in this example, the terminal molding part, the bending part, the branch pipe brazing part, and the flange brazing The occurrence of red rust (iron rust) was not observed all around the brazed part and the tack welded part for brazing.
[0018]
Comparative Example 1
Using the same stainless steel pipe for fuel cell piping as in Example 1, drilling, terminal bulging, bending, branch pipe and flange tack welding under the same conditions as in Example 1, and ordinary silver brazing Then, the same evaluation test as in Example 1 was performed on the fuel cell piping obtained by performing normal cleaning with an alkaline degreasing solution, and the occurrence of rust was observed. Red rust was observed on the section and the cut end face of the tube. Moreover, linear red rust was confirmed in the portion rubbed with the cored bar in the bent portion, and further red rust was confirmed in the junction between the branch pipe and the flange. This occurs because metal powder other than stainless steel that adheres to existing steel pipe manufacturing equipment during cutting and bending processes adheres to the stainless steel pipe and corrodes it. This may be due to the generation of harmful iron ions.
[0019]
【Effect of the invention】
As described above, the fuel cell piping made of stainless steel according to the present invention is inexpensive, has a clean inner surface, and has a good quality free from residual or generated harmful ions that hinder the catalytic reaction. In addition, according to the method of the present invention, a fuel cell pipe made of stainless steel with a good quality that has a clean inner surface and no harmful ion residue or generation that interferes with the catalytic reaction can be used in a normal manner other than a stainless steel pipe dedicated equipment. There is an excellent effect that it can be manufactured at low cost by the pipe manufacturing facility.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a fuel cell pipe made of stainless steel according to the present invention and having a spool provided at a pipe end.
FIG. 2 is a side view showing an example of a fuel cell pipe made of stainless steel according to the present invention and having a flange attached to the end of the pipe.
FIG. 3 is a side view showing an example of a fuel cell pipe made of stainless steel according to the present invention and having a bracket attached to the outer surface of a pipe body.
FIG. 4 is a partially broken side view showing an example of a fuel cell pipe in which a nipple is attached to a pipe body in the stainless steel fuel cell pipe according to the present invention.
FIG. 5 is a partial enlarged view showing another example of another fuel cell pipe in which a flange is brazed to the end of the stainless steel fuel cell pipe according to the present invention.
FIG. 6 is a manufacturing process diagram showing one embodiment of a method for manufacturing a fuel cell pipe according to the present invention.
FIG. 7 is a manufacturing process diagram showing still another embodiment.
FIG. 8 is a manufacturing process diagram of the fuel cell pipe shown in FIG. 1;
FIG. 9 is a manufacturing process diagram of the fuel cell pipe shown in FIG. 2;
FIG. 10 is a manufacturing process diagram of the fuel cell pipe shown in FIG. 3;
FIG. 11 is a manufacturing process diagram of the fuel cell pipe shown in FIG. 4;
[Explanation of symbols]
11, 12, 13, 14, 15 Fuel cell piping 11-1, 12-1 13-1, 14-1, 15-1 Tubing 11-2 Spool 12-2, 14-2, 15-2 For fastening Flange 13-3 Fastening bracket 14-3 Fastening nipples 12-3, 13-4, 14-4, 14-5, 15-3 Ni brazing portion 15-4 Ni brazing material 21 Cutting step 22 Molding step 23 Drilling Process 24 Tacking process 25 Brazing / solid solution heat treatment process 26 Inner surface cleaning process 27 Chemical Ni plating process

Claims (2)

Cutting step, forming step, perforation step, tacking step, any required process and inner surface cleaning process and stainless steel fuel cells by Ri Manufacturing production line consisting of brazing, solid solution heat treatment step a use pipes, said metal powder adhering to at least the inner surface of the tube including the end face on the inner surface cleaning treatment step after facilities the cleaning process of dissolving and removing, chemical Ni plating process chemical to at least inner surface including the end face of Ni piping for a fuel cell ing plated. Cutting step, forming step, perforation step, tacking step, any required process and inner surface cleaning treatment step and piping by squirrels stainless steel fuel cell manufacturing line consisting of brazing, solid solution heat treatment step In the manufacturing method, after performing a cleaning process for dissolving and removing metal powder adhering to at least the inner surface of the pipe including the end surface in the inner surface cleaning process , the chemical Ni plating is performed on at least the inner surface of the pipe including the end surface in the chemical Ni plating process. The manufacturing method of piping for fuel cells characterized by performing these.

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