JP4418361B2 - Al-Zn alloy sprayed coating Al alloy member, manufacturing method thereof, and open rack vaporizer type liquefied natural gas vaporizer - Google Patents

Description

  The present invention belongs to a technical field relating to an Al-Zn alloy sprayed coating-coated Al alloy member, a method for producing the same, and an open rack vaporizer type liquefied natural gas vaporizer, and in particular, a heat exchange panel for a liquefied natural gas vaporizer In the technical field of Al-Zn alloy sprayed coating coated Al alloy member and its manufacturing method, which is difficult to swell and peel even under the environment such as the usage environment of the header and header (excellent in swelling resistance and peeling resistance) is there.

  Liquefied natural gas (hereinafter also referred to as LNG) is usually transported and stored in a liquid state of low temperature and high pressure, and is vaporized in advance when used. In this vaporization, an open rack vaporizer (hereinafter also referred to as ORV) has been used to vaporize a large amount of LNG. This ORV is a type of heat exchanger that heats and vaporizes LNG through heat exchange with seawater. That is, seawater is stored in the trough from the watering nozzle, and dripping while wetting the outside of the panel (heat transfer tube) from both side edges, while the LNG sent to the panel (heat transfer tube) exchanges heat with the seawater. And vaporized in the panel (heat transfer tube).

  This ORV member, especially panel (heat transfer tube) member, is made of Al alloy such as JIS 3203 which has good thermal conductivity, can be easily processed into a complex shape to increase the heat transfer area, and has good weldability. Yes. However, Al alloy originally has a drawback that it is easily corroded when immersed in seawater, and once erosion starts, the eroded portion is intensively eroded and is susceptible to so-called perforated pitting.

  For this reason, anticorrosion treatment has been actively studied for Al alloys used in the above-mentioned applications, and at present, anticorrosion methods using sacrificial anticorrosive action occupy the mainstream. In this sacrificial protection, the surface of a base alloy made of an Al alloy is coated with a metal that is more easily corroded than the base metal alloy, that is, an alloy having a high ionization tendency and having a lower corrosion potential in seawater than the base metal alloy. It is. As a result, initially, the base metal alloy is kept in direct contact with seawater due to the coating action of the coating alloy, so that the corrosion resistance is maintained, and part of the coating alloy is peeled off so that the base metal alloy is exposed and is in direct contact with seawater. Even in this case, the long-term corrosion resistance of the base alloy is ensured by the sacrificial anticorrosive action of the remaining coating alloy.

  Conventionally, an alloy of Al and Zn is known as a coating alloy having the sacrificial anticorrosive action, and alloys such as Al-2% Zn and Al-3% Zn are used. As a method for coating the base metal alloy of this alloy, for example, as described in JP-A-5-16496, a method of cladding an Al—Zn alloy by a thermal spraying method or the like to extend the surface protection for a long period of time. Has also been proposed.

In addition, in order to further enhance the sacrificial anticorrosive action, an Al-Zn coated alloy containing a trace amount of Hg, Sn, In, Ga, Cd, or an Al-Zn coated alloy with a Zn content of 3.5 to 85.0% is provided. Japanese Patent Laid-Open No. 6-317392. This technique can further enhance the sacrificial anticorrosive action than the coating alloys such as Al-2% Zn and Al-3% Zn because the trace content is added while increasing the Zn content.
Japanese Patent Laid-Open No. 5-164496 JP-A-6-317392

  However, ORV (Open Rack Vaporizer) has been increasing in efficiency in recent years, and tends to increase in size and operate continuously for a long time. For this reason, durability and reliability such as long-term corrosion resistance that can withstand the increase in the flow velocity of the falling seawater due to the increase in the size of the members constituting the ORV and continuous prolonged operation are required. However, in general, although the Al-Zn sprayed coating has Zn added, the surface is easily passivated by the action of Al. Therefore, when water enters the interface defect part with the Al alloy base material through the hole defects present in the sprayed coating, the active surface of the interface defect part where the potential becomes low due to the lack of dissolved oxygen, and the sprayed coating A battery (oxygen concentration battery) is formed between the passive portion where the electric potential of the outermost surface is increased, the interface portion is preferentially dissolved to cause interface destruction, and the sprayed film swells or peels off.

  In order to prevent the intrusion of water through pore defects in such a thermal spray coating, the sealing agent is impregnated after the thermal spray coating is applied, but the penetration of the sealing agent into the holes is insufficient. Therefore, satisfactory characteristics have not been obtained.

  The present invention has been made in view of such circumstances, and the object thereof is to prevent the sprayed film from being swollen or peeled off even under an environment such as a heat exchange panel or header usage environment of a liquefied natural gas vaporizer. Al-Zn alloy spray coating coated Al alloy member (excellent in blistering resistance and peeling resistance), its manufacturing method, and open rack vaporizer type LNG vaporizer with excellent durability of heat exchange panel and header members It is something to try.

  As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. According to the present invention, the above object can be achieved.

The present invention thus completed and capable of achieving the above object relates to an Al-Zn alloy spray-coated Al alloy member, a method for producing the same, and an open rack vaporizer type liquefied natural gas vaporizer, The Al-Zn alloy sprayed coating-coated Al alloy member according to Item 1 (Al-Zn alloy sprayed coating-coated Al alloy member according to the first invention), and the method for producing the Al-Zn alloy sprayed coating-coated Al alloy member according to Claim 2 (manufacturing method of the second according to the invention Al-Zn alloy sprayed coating covering Al alloy member), according to claim 3 open rack vapor riser type LNG vaporizer according (open rack vapor riser type liquefied natural gas according to the third invention Vaporizer), which has the following configuration.

That is, the Al-Zn alloy spray-coated Al alloy member according to claim 1 comprises a heat exchange panel and / or header of an open rack vaporizer type liquefied natural gas vaporizer, and has a thickness of 100 on the surface of the Al alloy member. Al-Zn alloy sprayed coating Al alloy member on which Al-Zn alloy sprayed coating of μm or more is formed , shot peening, grinder grinding, water jet peening or laser on the surface of the Al-Zn alloy sprayed coating When peened and impregnated with a sealing agent , the area ratio of pores observed in the region from the outermost surface to a depth of 100 μm is 10% or less when the sprayed film is observed from the cross-sectional direction. An Al—Zn alloy sprayed coating-coated Al alloy member characterized in that [First invention].

The process according to claim 2, wherein the Al-Zn alloy sprayed coating covering Al alloy member manufacturing the Al-Zn alloy sprayed coating covering Al alloy member manufacturing the Al-Zn alloy sprayed coating covering Al alloy member according to claim 1, wherein A spraying step in which an Al-Zn alloy is sprayed on the surface of an Al alloy member to form an Al-Zn alloy sprayed coating, and the surface of the Al-Zn alloy sprayed coating is shot peened and grindered after the spraying step. A machining step for machining by grinding, water jet peening or laser peening , and a sealing agent impregnation step for impregnating the sealing agent after the spraying step and before and / or after the machining step. A feature of the present invention is a method for producing an Al-Zn alloy spray-coated Al alloy member [ second invention].

Open rack vapor riser type LNG vaporizer of claim 3 wherein the heat exchange panel and / or members to claim 1, wherein the header Al-Zn alloy sprayed coating covering Al alloy member or claim 2, wherein the Al- An open rack vaporizer type liquefied natural gas vaporizer characterized in that an Al-Zn alloy sprayed coating-coated Al alloy member produced by a method for producing a Zn alloy sprayed coating-coated Al alloy member is used [ third invention ].

  According to the present invention, Al-Zn is less likely to cause blistering or peeling of the sprayed film even under an environment such as a heat exchange panel or header environment of a liquefied natural gas vaporizer (excellent in swelling resistance and peeling resistance). An alloy sprayed coating-coated Al alloy member is obtained.

  That is, according to the Al-Zn alloy sprayed coating coated Al alloy member according to the present invention, it is difficult for the sprayed coating to swell or peel even under an environment such as a heat exchange panel or header usage environment of a liquefied natural gas vaporizer, Excellent swelling and peeling resistance can be obtained.

  According to the method for producing an Al-Zn alloy sprayed coating-coated Al alloy member according to the present invention, such an Al-Zn alloy sprayed coating-coated Al alloy member according to the present invention can be obtained.

  According to the open rack vaporizer type liquefied natural gas vaporizer according to the present invention, the durability of the heat exchange panel and the header member can be improved.

As a result of intensive studies to achieve the above-mentioned object, the following knowledge was obtained. That is, when the thickness of the Al-Zn alloy sprayed coating of the Al-Zn alloy sprayed coating Al alloy member is 100 μm or more and the sprayed coating is observed from the cross-sectional direction, the depth from the outermost surface is 100 μm. If the pore area ratio observed in the area up to 10% is 10% or less, thermal spraying is performed even in an environment such as a heat exchange panel of LNG (liquefied natural gas) vaporizer or the environment in which the header is used (in a flowing seawater environment). Infiltration of water via pore defects in the film can be prevented, and therefore the formation of oxygen concentration cells (formed by the thermal spray coating surface and the interface defect part) can be suppressed, and the interface due to preferential dissolution of the interface part. It has been found that the occurrence of breakage can be prevented, and therefore the sprayed film is unlikely to swell or peel off (excellent in swelling resistance and peeling resistance). After forming the Al-Zn alloy sprayed film by thermal spraying, if the surface of this sprayed film is plastically deformed by machining, the outermost hole defects disappear or are reduced, and it is difficult for water to enter from the outside environment. Swelling and peeling of the sprayed film are less likely to occur. As the machining method, shot peening, grinder grinding, water jet peening, or laser peening is preferable. When the Al-Zn alloy sprayed film is impregnated with a sealing agent, the swell resistance and peel resistance can be further improved.

The present invention has been completed based on such findings. The Al-Zn alloy sprayed coating coated Al alloy member according to the present invention thus completed constitutes the heat exchange panel and / or header of the open rack vaporizer type liquefied natural gas vaporizer, and the surface of the Al alloy member An Al-Zn alloy sprayed coating coated Al alloy member with an Al-Zn alloy sprayed coating with a thickness of 100 μm or more , shot peening, grinder grinding, water on the surface of the Al-Zn alloy sprayed coating The area ratio of pores observed in the region from the outermost surface to a depth of 100 μm when jet peening or laser peening and impregnation with a sealant are performed and the sprayed film is observed from the cross-sectional direction. Is an Al-Zn alloy sprayed coating-coated Al alloy member, characterized in that is 10% or less. This Al-Zn alloy sprayed coating coated Al alloy member is resistant to blistering and peeling resistance even in environments such as liquefied natural gas vaporizer heat exchange panels and headers where it is difficult to swell or peel off. Is excellent.

  The pore area ratio is the area ratio of the pores. More specifically, the area of the region R of the cross section to be observed is A, and the area of the pores observed in this region R (in the case of a plurality of pores) 100 × B / A, where B is the sum of the areas. The pores are holes (holes) in the sprayed film, and even if this hole is filled with a sealing agent and sealed, this portion is referred to as (represents) a pore. Accordingly, the pores in the pore area ratio include those filled with the sealing agent in this way and sealed.

  The pore area ratio in the region from the outermost surface of the Al—Zn alloy sprayed film (hereinafter also referred to as a sprayed film) to a depth of 100 μm is obtained, for example, as follows. That is, as shown in FIGS. 1 and 2 (SEM observation image), in an image obtained by observing a cross section of about 1 mm × 1 mm square of the sprayed film at a magnification of about 150 to 160 times, 100 × 100 in contact with the outermost surface of the sprayed film. The μm region is set as the entire region of the SEM observation image, and the area ratio of pores observed in each 100 μm × 100 μm region is obtained, and this is obtained by arithmetic averaging.

  The pore area ratio (the area ratio of the porosity) is calculated as follows, for example. In other words, the corresponding region image of 100 μm × 100 μm in the SEM image is projected on a CCD image sensor, divided into 512 × 480 pixels (240,000 pixels), and 256 levels of 0 to 255 for each pixel. The key is divided into keys (degrees of brightness). In this gradation division, the intermediate value between the gradation value of the sprayed film part and the gradation value of the pore center part is defined as the boundary between the sprayed film and the pores, and the area ratio of the pore part and the sprayed film part is determined from this information. . As an image processing device, Keyence's high-speed, high-precision image processing system XV-1000 (Vision Tree System without a program) is recommended.

  To increase the measurement accuracy of the pore area ratio, an observation magnification of 100 times or more is recommended. FIG. 1 is an example of an SEM observation image of an Al—Zn alloy sprayed film (as it is sprayed), and pores are observed in almost all regions, and the pore area ratio is high. On the other hand, Fig. 2 is an example of SEM observation image of the surface of Al-Zn alloy sprayed film formed by spraying with a grinder. Many pores are observed in the deep part of the sprayed film. However, in the region from the outermost surface to a depth of 100 μm, the pores are mechanically sealed by grinder processing, and the pore area ratio is extremely small.

  In the Al-Zn alloy sprayed coating Al alloy member according to the present invention, the pore area ratio observed in the region from the outermost surface of the Al-Zn alloy sprayed coating to a depth of 100 μm is 10% or less. This is because if the thickness is too high, the blistering resistance and peel resistance are lowered and become insufficient.

  The requirement that the pore area ratio is 10% or less is meaningless even if it is locally achieved in a part of the sprayed film, and it is desirable that it is achieved as much as possible in the entire sprayed film coated surface. For this reason, it is desirable to obtain the pore area ratio for as many cross sections as possible. For example, it is desirable that 10 or more samples are randomly extracted from the target region of the sprayed film, and the pore area ratio is obtained in each cross-sectional observation image. In this case, the arithmetic average of these pore area ratios only needs to satisfy 10% or less.

  The smaller the pore area ratio, the less likely water will enter from the outside environment, and the more the resistance to blistering / peeling will be improved. Therefore, the pore area ratio is preferably 6% or less, and more preferably 2% or less. It is desirable that

  Although it is difficult to completely eliminate the hole defects in the sprayed film, the smaller the hole defect density, the more reliably the water intrusion from the outside environment is blocked, and the blistering resistance and peeling resistance are further improved. It is desirable to make the hole defect density as small as possible.

  In the Al-Zn alloy sprayed coating Al alloy member according to the present invention, the thickness of the Al-Zn alloy sprayed coating is set to 100 μm or more. This is because the base Al alloy member is exposed, and the corrosion resistance is lowered and becomes insufficient. In addition, if the defect density of the sprayed film is the same, the thicker the sprayed film, the higher the external environment blocking ability. Therefore, the thickness of the sprayed film is preferably 150 μm or more, and more preferably 200 μm or more. desirable. However, if the sprayed film is too thick, the residual compressive stress of the sprayed film is accumulated by an increase in the film thickness, and a large interfacial fracture force is generated and the film is easily peeled off. In view of this prevention, the thickness of the sprayed film is preferably 2 mm or less, more preferably 1.5 mm or less, and further preferably 1 mm or less.

  The Zn composition of the Al-Zn alloy sprayed film is not particularly limited and can be applied in almost the whole range. However, when Zn is less than 0.5% by mass, the sacrificial corrosion resistance of the sprayed film on the aluminum base material is insufficient. Zn: 0.5 mass% or more is desirable, Zn: 1 mass% or more is desirable, and Zn: 1.5 mass% or more is even more desirable. Further, when the Zn content exceeds 85% by mass, a sufficient sacrificial anticorrosive effect can be obtained. However, since the sprayed film dissolves early and the film life becomes short, it is desirable that Zn: 85% by mass or less. : 70 mass% or less is desirable, and Zn: 60 mass% or less is more desirable.

By eliminating the hole defects in the outermost layer of the Al-Zn alloy sprayed film, it is possible to prevent water from entering from the outside environment, and thus improve the swell resistance and peel resistance. In order to obtain such a sprayed coating, it is effective to form an Al—Zn alloy sprayed film by spraying and then plastically deform the surface of the sprayed film by machining. As the machining method, shot peening, grinder grinding, water jet peening, or laser peening is preferable. Also, before the surface of the Al-Zn alloy sprayed film is machined, the sprayed film is impregnated with a sealing agent, and then machined. Since it is double-blocked by the part, it is possible to further improve the swell resistance and peel resistance. After machining the surface of the Al-Zn alloy sprayed film, impregnating with a sealing agent can fill hole defects that could not be sealed by machining and further improve swell resistance and peel resistance. Can do.

Therefore, a method for producing an Al-Zn alloy sprayed coating-coated Al alloy member according to the present invention includes a thermal spraying step of spraying an Al-Zn alloy on the surface of an Al alloy member to form an Al-Zn alloy sprayed coating, and the thermal spraying described above. A machining process in which the surface of the Al-Zn alloy sprayed film is machined by shot peening, grinder grinding, water jet peening or laser peening after the process, and after the spraying process and before and / or after the machining process. And a sealing agent impregnation step for impregnating the sealing agent . A method for producing an Al-Zn alloy sprayed coating-coated Al alloy member [ second invention].

According to this manufacturing method, the surface layer is plastically deformed during the machining of the Al-Zn alloy sprayed coating surface, and the outermost layer hole defects disappear or are reduced , and further impregnated with a sealing agent. The Al-Zn alloy sprayed coating-coated Al alloy member having excellent swelling resistance and peeling resistance can be obtained.

  Various optimum values can be considered for the shot peening conditions depending on the diameter of the hard sphere used and the jetting speed, but it is only necessary to satisfy the pore area ratio of the thermal sprayed film according to the present invention regardless of the conditions. From the viewpoint of securing swell resistance and peel resistance, it is recommended that the film thickness be reduced by 50 μm or more from the initial film thickness of the sprayed film.

  Moreover, various optimum values can be considered for the conditions of the grinder depending on the grinding jig to be used. However, it is sufficient that the pore area ratio of the thermal sprayed film according to the present invention can be satisfied regardless of the conditions. From the viewpoint of securing swell resistance and peel resistance, it is recommended that the film thickness be reduced to 150 μm or more from the initial film thickness of the sprayed film.

  When applied to ORV heat exchange panels and headers, it is difficult to properly control the residual film thickness after machining with the above shot peening or grinder, but it is important to carefully control this. It is. If the residual film thickness is less than 100 μm, the spraying film itself has insufficient corrosion allowance and the aluminum base material is exposed to seawater at an early stage. Therefore, it is necessary to make the residual film thickness 100 μm or more. Further, the residual film thickness is preferably 150 μm or more, and more preferably 200 μm or more.

  In order to prevent the film from becoming too thin due to shot peening or grinder, it is conceivable to apply a thick sprayed film. However, if the residual film thickness exceeds 1000 μm (1 mm), the film will be exfoliated due to film stress. The thickness is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less. As can be seen from these, there is not much room in the film thickness range.

  Ultrasonic film is appropriately applied to each part while performing shot peening and grinder grinding treatment so that the residual film thickness falls within the range of 100 to 1000 μm, and in particular, in order not to generate a part that is too thin locally. It is important to monitor the film thickness with a thickness gauge or the like.

  As the above-mentioned sealant, a commonly used sealant may be used. However, SA clear (manufactured by Shinto Paint Co., Ltd.), a polymer epoxy resin excellent in permeability to Al-Zn alloy sprayed film, is sprayed. It is recommended to apply at least once to the film surface.

The Al-Zn alloy sprayed coating coated Al alloy member according to the present invention is resistant to blistering and peeling even in a flowing seawater environment, and is excellent in swelling resistance and peeling resistance. can be suitably used as a constituent member of the heat exchange panel and / or header, Ru can improve their durability. The ORV type LNG vaporizer in which the Al-Zn alloy sprayed coating-coated Al alloy member according to the present invention is used for the heat exchange panel and / or header member is excellent in the durability of the member [ third invention ].

In the present invention, the composition, shape, etc. of the Al alloy member (base material on which the Al—Zn alloy sprayed coating is coated) are not limited. The composition of the Al—Zn alloy in the Al—Zn alloy sprayed film is not limited as described above. The Al-Zn alloy contains Al and Zn, and is not limited to containing only Al and Zn, and can contain elements other than Al and Zn as necessary. Impurities can be included. Therefore, this Al—Zn alloy can also be called an Al—Zn alloy.

  Examples of the present invention and comparative examples will be described below. The present invention is not limited to this embodiment, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are within the technical scope of the present invention. include.

  An Al alloy plate (A5083) was prepared in a size of 200 mm x 200 mm x 5 mm (thickness), and Al-2 mass% (hereinafter referred to as%) Zn alloy was sprayed on one side of the Al alloy plate to produce Al- A 2% Zn alloy sprayed coating was applied. The thickness of this thermal sprayed film is 250 μm for No. 1 and 2 in Table 1 below, 300 μm for No. 3, and 300 μm for No. 4 in consideration of the thickness reduction due to machining described below. Films were formed with 400 μm, No. 5 as 300 μm, and Nos. 6, 7, 8, and 9 as 350 μm as target values.

  Next, the treatments of Nos. 2 to 9 shown in Table 1 were performed on the Al alloy plate (Al-2% Zn alloy sprayed coating-coated Al alloy plate) after the sprayed coating. At this time, the number of processed sheets (n number) was 11 sheets each. That is, 11 sheets were processed for each number. In Table 1, No. 1 is the non-treated material, that is, the Al-2% Zn alloy sprayed coating Al alloy plate (as sprayed). A circle indicates that the processing described in the column above the circle has been performed. For example, No. 2 was only subjected to a sealant impregnation treatment after thermal spraying, No. 4 was subjected to only grinder grinding for 10 seconds after thermal spraying, No. 7 No. 9 is impregnated with sealant after spraying, and shot peened for 60 seconds, No. 9 is impregnated with sealant after spraying, and then shot peened for 60 seconds. After this, it shows that the sealing agent is impregnated.

  The thickness of the sprayed coating of the Al-2% Zn alloy sprayed coating Al alloy plate after the treatment of Nos. 3 to 9 was set to 250 μm. There were variations between N number of 11 sheets, but all were within the range of 200-300 μm. In addition, the thickness of the sprayed film of No. 1 is the thickness as it is sprayed (target value 250 μm), and the thickness of the sprayed film after the treatment of No. 2 is the same as that of the sprayed film (target value 250). These thicknesses are all in the range of 200 to 300 μm.

[Measurement of pore area ratio of sprayed film]
Al-2% Zn alloy sprayed coating Al alloy plate after the treatment of No. 2-9 (hereinafter referred to as Al-2% Zn alloy sprayed coating Al alloy plate) About the sprayed film (Al-2% Zn alloy sprayed film) of .1, the pore area ratio in the region from the outermost surface of the sprayed film to a depth of 100 μm was measured. At this time, each one was used as a test specimen for measurement. This measurement was performed as follows. That is, 10 portions were cut out evenly from the 200 mm x 200 mm area of the measurement specimen, and the cross section of the sprayed film was observed by SEM in the same manner as in the examples of FIGS. 1 and 2, and each 100 μm deep from the outermost surface of the sprayed film. The area ratio of the pores observed in the region up to was determined. And the average value of this value (value of 10 points) was calculated | required, and this was made into the pore area ratio in the area | region from the outermost surface of a sprayed film to the depth of 100 micrometers.

(Bulging peel test)
The blistering peeling test was done about the thermal sprayed film coating Al alloy plate of No.2-9 after the above-mentioned treatment, and No. 1 thermal sprayed film coating Al alloy plate (those with thermal spraying). At this time, 10 sheets were used as test pieces. This test was performed as follows. In other words, the test piece was immersed in artificial seawater at 20 ° C, pH 8.2, and flow rate of 3m / sec for 3 months, and the test piece after this exposure test was bent so that the sprayed film was inside. Then, the state of occurrence of blistering and peeling of the sprayed film that occurred when compressive stress was applied to the sprayed film was observed, and the area ratio of blistering and peeling of the sprayed film was examined. And the average value of this value (value of 10 sheets) was calculated | required, and this was made into the blistering peeling area rate of a sprayed film.

〔result〕
Table 2 shows the results of the measurement of the pore area ratio (hereinafter referred to as the pore area ratio) in the region from the outermost surface of the sprayed film to a depth of 100 μm and the result of the blistering peeling test.

  As can be seen from Table 2, the No. 1 spray-coated Al alloy plate (as sprayed) has a pore area ratio of 21.6% and a swollen peel area ratio of 48.5%.

   The No. 2 sprayed coating-coated Al alloy plate has a porosity area ratio (hereinafter also referred to as porosity) of 22.4%, and the No. 1 sprayed coating-coated Al alloy plate (as sprayed) This is almost the same as the above case, but since the pores are impregnated with the sealing agent, the swollen peeling area ratio is improved to 22.3%. At present, this specification is applied as a component for heat exchange panels and headers of ORV type LNG vaporizers, but further improvements in characteristics are required.

   The sprayed coating-coated Al alloy plate after No. 3 treatment was grinded for 1 second after spraying, but the porosity decreased to 12.4% and the swollen peel area ratio improved to 23.5%. Therefore, characteristics equivalent to the current specifications are obtained without using a sealant.

   The sprayed film-coated Al alloy sheet after the treatment of No. 4 was subjected to grinder grinding for 10 seconds after spraying, the porosity decreased to 9.6%, and the swollen peel area ratio improved to 5.7%. This is a level that can be used more favorably than the current specifications as a component for heat exchange panels and headers of ORV type LNG vaporizers. As can be seen from this, when the porosity becomes 10% or less, a heat exchange panel or header component of the ORV type LNG vaporizer can be used more suitably than the current specification.

   The sprayed coating-coated Al alloy sheets No.5 and 6 were shot peened after spraying for 30 seconds and 60 seconds, and the porosity was further reduced to 5.8% and 1.7%. Will be further improved to 3.5% and 2.3%. As can be seen from this, the porosity is preferably 6% or less, and more preferably 2% or less. When the porosity is thus small, it can be more suitably used as a constituent member of a heat exchange panel or header of an ORV type LNG vaporizer.

   The sprayed coating-coated Al alloy plate after the treatment of No. 7 was subjected to shot peening for 60 seconds after impregnation with a sealing agent after spraying. The porosity was almost the same as in the case of No. 6 above, but the swollen peel area ratio was improved to 0.7% by the synergistic effect of the sealing agent effect and the shot peening effect.

   The sprayed coating-coated Al alloy plate after the treatment No. 8 is obtained by impregnating a sealing agent after performing shot peening for 60 seconds. The porosity was the same as in Nos. 6 and 7, but the swollen peel area ratio was improved to 0.8% due to the synergistic effect of the shot peening effect and the sealant effect.

   The sprayed coating-coated Al alloy plate after the treatment No. 9 was impregnated with a sealing agent after spraying, then subjected to shot peening for 60 seconds, and then further impregnated with a sealing agent. The porosity was the same as in the cases of Nos. 6, 7, and 8. However, the sealing agent effect was doubled and the swollen peel area ratio was improved to 0.2%.

  The Al-Zn alloy sprayed coating coated Al alloy member according to the present invention is resistant to blistering and peeling even in a flowing seawater environment, and is excellent in swelling resistance and peeling resistance. It can be suitably used as a constituent member for heat exchange panels and headers, and is useful because it can improve durability.

It is a figure which shows the state of the cross section about Al-Zn sprayed-film coating | cover Al alloy material (thing as sprayed). It is a figure which shows the state of the cross section about Al-Zn spray coating Al alloy material (what grinder-processed the Al-Zn spray coating surface after spraying).

Claims (3)

Al-Zn alloy sprayed film with an Al-Zn alloy sprayed film with a thickness of 100 μm or more formed on the surface of the Al alloy member constituting the heat exchange panel and / or header of the open rack vaporizer type liquefied natural gas vaporizer A coated Al alloy member, wherein the surface of the Al-Zn alloy sprayed coating is subjected to shot peening, grinder grinding, water jet peening or laser peening, and impregnation with a sealant , An Al-Zn alloy sprayed coating-coated Al alloy member characterized in that the pore area ratio observed in the region from the outermost surface to a depth of 100 μm when observed from the cross-sectional direction is 10% or less. An Al-Zn alloy sprayed coating-coated Al alloy member manufacturing method according to claim 1, wherein the Al-Zn alloy sprayed coating Al alloy member is coated with Al-Zn alloy on the surface of the Al alloy member. -Zn alloy sprayed film forming process, and after the spraying process, a machining process for machining the surface of the Al-Zn alloy sprayed film by shot peening, grinder grinding, water jet peening or laser peening, and the spraying process. And a sealing agent impregnation step of impregnating the sealing agent before and / or after the machining step. A method for producing an Al-Zn alloy sprayed film-coated Al alloy member. The Al-Zn alloy sprayed coating-coated Al alloy member according to claim 1 or the Al-Zn alloy sprayed coating-coated Al alloy member according to claim 2 is used as a heat exchange panel and / or header member. An open rack vaporizer type liquefied natural gas vaporizer characterized by using a Zn alloy sprayed coating coated Al alloy member.

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