Method for producing pressure vessel

Abstract

To provide a technique for preventing the occurrence of voids at the interface between a base member and a barrier layer during a heating step for forming the barrier layer on the inner surface of the base member.SOLUTION: The present invention provides a method for producing a pressure vessel 10 comprising a body base 22 composed of a base material containing a volatile component to vaporize under heat, and a barrier layer 24 formed by heating a barrier material applied to the inner surface of the body base 22. This production method involves a preheating step to vaporize the volatile component in the base material through heating of the body base 22 prior to application of the barrier material to its inner surface.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a pressure vessel. [Background technology]

[0002] The high-pressure tank disclosed in Patent Document 1 is a tank for storing high-pressure hydrogen gas, and includes a cylindrical body and a pair of hemispherical dome sections provided at both ends of the body. The body has a hollow reinforcing layer made of a metal material such as an aluminum alloy, and a barrier layer provided inside the reinforcing layer. The barrier layer prevents hydrogen gas from leaking from the inside to the outside. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-108937 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration in which a barrier layer is provided as an inner layer of the body (an inner layer of the base member) as in Patent Document 1, for example, a barrier layer is formed by applying a barrier material to the inner surface of the base member, melting it by heat treatment, and then bonding it. However, if the base member contains vaporizable components, the vaporizable components may vaporize during heat treatment, causing voids to form between the base member and the barrier layer.

[0005] The present invention was developed based on the above-mentioned circumstances, and aims to provide a technology that can suppress the generation of voids at the interface between a base member and a barrier layer during a heating process for forming a barrier layer on the inner surface of the base member. [Means for solving the problem]

[0006] The method for producing a pressure vessel of the present invention comprises the steps of: A method for manufacturing a pressure vessel comprising: a base member having a base material containing a vaporizable component that vaporizes when heated; and a barrier layer formed by heat-treating a barrier material applied to an inner surface of the base member, the method comprising the steps of: Before the barrier material is applied to the inner surface, a pre-heating process is performed in which the base member is heated to vaporize the vaporizable components of the base material. Effect of the Invention

[0007] According to the method for manufacturing a pressure vessel of the present invention, before the barrier material is applied to the inner surface of the base member, the vaporized components of the base material can be vaporized by a pre-heating process and released to the outside of the base member. Therefore, in the heat treatment process for forming the barrier layer, the vaporized components of the base material are reduced, so that the generation of voids at the interface between the base member and the barrier layer can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a pressure vessel of a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a pressure vessel. [Diagram 3] FIG. 4 is an explanatory diagram illustrating a manufacturing process of the body base body. [Figure 4] FIG. 1 is an explanatory diagram showing a configuration for heating an object to be heated using a thermostatic bath. [Diagram 5] FIG. 2 is an explanatory diagram showing a configuration for heating an object to be heated using an infrared heater. [Figure 6] FIG. 1 is an explanatory diagram showing a configuration for heating an object to be heated using an infrared heater and a cooling device. [Figure 7] FIG. 5 is an explanatory diagram showing the time course of various temperatures when a heat treatment is performed in the configuration of FIG. [Figure 8] FIG. 6 is an explanatory diagram showing the time course of various temperatures when a heat treatment is performed in the configuration of FIG. 5. [Figure 9] FIG. 7 is an explanatory diagram showing the time course of various temperatures when a heat treatment is performed in the configuration of FIG. 6. [Figure 10]FIG. 1 is an explanatory diagram of analysis results showing the relationship between vaporized components in a member made of carbon fiber reinforced plastic (CFRP) and the amount of vaporized components generated depending on temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the method for producing a pressure vessel of the present invention, the heating temperature in the pre-heating treatment is preferably higher than the heating temperature during formation of the barrier layer. According to this configuration, by performing the pre-heating process at a temperature higher than the heating temperature during the barrier layer formation, most of the vapor components that may be vaporized from the base member at the heating temperature during the barrier layer formation can be vaporized in advance and released into the atmosphere, thereby effectively suppressing voids that may be generated by heating during the barrier layer formation.

[0010] In the method for manufacturing a pressure vessel of the present invention, it is preferable that the pre-heating treatment includes heating both the inner surface and the outer surface of the base member. According to this configuration, the base member is heat-treated from both its inner and outer surfaces, so that the vaporization of the vaporization component in the base member can be efficiently carried out.

[0011] In the method for producing a pressure vessel of the present invention, it is preferable that the pre-heating treatment and the heating treatment during the formation of the barrier layer are carried out using the same heater. According to this configuration, the heater can be used both for the preliminary heating process and for the heating process when forming the barrier layer, and the manufacturing cost can be reduced.

[0012] In the method for producing a pressure vessel of the present invention, it is preferable that the heating time in the pre-heating treatment is longer than the heating time in forming the barrier layer. According to this configuration, the vaporized components in the base member are sufficiently vaporized, while deterioration of the barrier layer is easily suppressed.

[0013] In the method for manufacturing a pressure vessel of the present invention, it is preferable to cool the outer surface of the base member during the heat treatment for forming the barrier layer. According to this configuration, by cooling the outer surface of the base member, it is possible to suppress the evaporation of the evaporation components on the outer surface side of the base member, and therefore it is possible to reduce the evaporation of the evaporation components in the entire base member when forming the barrier layer, and it is possible to suppress the generation of voids.

[0014] First Embodiment A first embodiment of the present invention will now be described with reference to FIGS. 1 to 3. FIG.

[0015] (Construction of pressure vessel) The pressure vessel 10 of the first embodiment has a cylindrical capsule shape as shown in Fig. 1. The pressure vessel 10 is mounted on a vehicle, for example, and used as a container filled with high-pressure hydrogen gas. Note that the pressure vessel 10 and a portion thereof shown in Figs. 1 to 3 are exaggerated in terms of the diameter, axial length, thickness of each layer, etc., and the configuration shown in Figs. 1 to 3 is merely an example.

[0016] As shown in Fig. 1, the pressure vessel 10 comprises a body section 20 and a dome section section 30. The pressure vessel 10 is formed by combining the body section 20 and the dome section section 30. The pressure vessel 10 has barrier properties. In this first embodiment, the barrier properties are defined as the property of preventing or inhibiting a fluid (such as hydrogen gas) filled in the pressure vessel 10 from permeating the pressure vessel 10 and leaking to the outside of the pressure vessel 10.

[0017] As shown in Fig. 2, the body section 20 has a body base body 22 and a barrier layer 24. The body base body 22 corresponds to an example of the "base member" of the present invention. The body base body 22 has a cylindrical shape that is long in the axial direction (direction along the axis L1). The inner diameter dimension of the body base body 22 is constant over the entire length. The outer diameter dimension of the body base body 22 is constant over the entire length.

[0018] The trunk base body 22 includes a base material made of fiber-reinforced resin such as carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP). The base material includes a vaporizable component that vaporizes when heated. The vaporizable component is, for example, butanediol, 2-ethylhexyl acrylate, a polyol compound, an imidazole compound, butanediol diglycidyl ether, butyl acrylate, and other acrylic compounds.

[0019] The trunk base 22 is formed by, for example, winding a fiber bundle (not shown) impregnated with liquid thermosetting resin or a fiber bundle impregnated with thermosetting resin in a semi-cured state (prepreg fiber) into a hoop by, for example, a filament winding method. The fiber bundle is made by bundling thread-like fibers made of carbon fiber, glass fiber, Kepler fiber, etc.

[0020] As shown in Fig. 2, the barrier layer 24 is provided so as to cover the entire area of ​​the inner surface (inner circumferential surface, the same applies below) of the body base 22. The barrier layer 24 is cylindrical. The barrier layer 24 has barrier properties. Examples of materials (barrier materials) used for the barrier layer 24 include EVOH (ethylene-vinyl alcohol copolymer) and PA6 (nylon 6). The barrier layer 24 is used for the purpose of blocking or suppressing the permeation of the fluid stored in the pressure vessel 10 to the outside.

[0021] The barrier layer 24 is formed by heat treating a barrier material applied to the inner surface of the body substrate 22. The barrier material is applied to the inner surface of the body substrate 22, for example, in a powder state. The barrier material is applied to the inner surface of the body substrate 22, for example, by electrostatic coating.

[0022] As shown in FIG. 1, the dome section divided body 30 has a dome section base 31 and a barrier layer (not shown) provided on the inside of the dome section base 31. The dome section base 31 is a hemispherical part connected to the end of the body base 22 in the longitudinal direction. The diameter of the dome section base 31 decreases as it moves away from the body base 22. The dome section base 31 is made of, for example, the same material as the body base 22. The dome section base 31 is formed by laminating, for example, a fiber bundle (not shown) impregnated with a liquid thermosetting resin, or a fiber bundle impregnated with a thermosetting resin in a semi-cured state (prepreg fiber) by, for example, a hand layup method, and molding the molded product into a spherical shell shape, and dividing the molded product in half. The fiber bundle is a bundle of thread-like fibers made of carbon fiber, glass fiber, Kepler fiber, etc. The barrier layer (not shown) provided on the inside of the dome base 31 is made of the same material as the barrier layer 24.

[0023] (Pressure vessel manufacturing equipment) 3 (hereinafter, simply referred to as the manufacturing apparatus 40) is used to manufacture the body section 20 of the pressure vessel 10. The manufacturing apparatus 40 includes a heater 42 and a cooling device 44.

[0024] The heater 42 heats the inner surface of the trunk base 22. The heater 42 is configured as a rod heater that radiates infrared rays. The rod heater is configured, for example, with a heating body (e.g., nichrome wire, etc.) built into a metal sheath. The heater 42 radiates electromagnetic waves with a wavelength that matches the type of barrier material. For example, when the barrier material is EVOH, the heater 42 radiates infrared rays (mid- to far-infrared rays) that have a high absorption rate. By using an infrared heater as the heater 42, it is possible to reduce the space required for the equipment compared to a configuration that uses a thermostatic bath, etc.

[0025] The cooling device 44 is a device that cools the outer surface (outer peripheral surface, the same applies below) of the body base 22. The cooling device 44 includes, for example, a cooling member 46 and a cooler 48. The cooling member 46 is made of a material such as aluminum or copper. The cooling member 46 is, for example, cylindrical, and contacts the entire outer surface of the body base 22 so as to cover the entire outer surface of the body base 22. The cooler 48 is configured as, for example, an air-cooled heat exchanger (air-cooled radiator), a water-cooled heat exchanger, or the like. The cooling method by the cooler 48 is not particularly limited and may be air-cooling, liquid cooling, or the like.

[0026] (Pressure vessel manufacturing method) Next, a method for manufacturing a pressure vessel will be described. The method for manufacturing a pressure vessel includes a process for manufacturing the body section 20. The process for manufacturing the body section 20 includes a pre-heating process and a barrier layer forming process.

[0027] In the pre-heating step, a pre-heating treatment is performed to heat the body substrate 22 before the barrier material is applied to the inner surface of the body substrate 22. In the pre-heating step, the vaporized components of the body substrate 22 are vaporized. For example, as shown in FIG. 3, a heater 42 configured as a rod heater that radiates infrared rays is inserted inside the body substrate 22. The axis of the heater 42 is aligned with the axis line L1 of the body substrate 22. The inner surface of the body substrate 22 is heated by the heater 42.

[0028] In this way, the vaporized components of the base material of the body substrate 22 can be vaporized in advance and released into the atmosphere by a pre-heating process before the barrier material is applied to the inner surface of the body substrate 22. Therefore, in the subsequent heat treatment in the barrier layer formation process, the vaporized components of the base material are reduced, so that the generation of voids at the interface between the body substrate 22 and the barrier layer 24 can be suppressed.

[0029] The pre-heating treatment is preferably performed on both the inner and outer surfaces of the body substrate 22. For example, the inner surface of the body substrate 22 is heated by the heater 42, and the outer surface of the body substrate 22 is heated by a separately provided heater (e.g., an infrared heater). This allows the body substrate 22 to be heated on both the inner and outer surfaces, thereby enabling efficient vaporization of the vaporized components.

[0030] In the subsequent barrier layer forming process, first, a barrier material is applied to the inner surface of the body base 22. The barrier material is, for example, in powder form. Electrostatic coating is preferably used for applying the barrier material. The barrier material applied to the inner surface of the body base 22 is then heat-treated and thermally melted. The barrier material is then cooled and solidified to form the barrier layer 24. For example, the barrier layer 24 is naturally cooled in an atmospheric environment to be fixed to the body base 22.

[0031] In the barrier layer forming process, both the barrier material and the inner surface of the body substrate 22 are heat-treated, and at the same time, the outer surface of the body substrate 22 is cooled (reverse surface cooling). For example, a heater 42 configured as a rod heater that radiates infrared rays is inserted inside the body substrate 22 to heat the barrier material and the inner surface of the body substrate 22. For example, as shown in FIG. 3, the body substrate 22 is cooled by a cooling device 44. A cooling member 46 is brought into contact with the outer surface of the body substrate 22 so as to cover the entire outer circumferential surface of the body substrate 22. Then, the outer surface of the body substrate 22 is cooled by a cooler 48 via the cooling member 46. In this way, by rapidly cooling the outer surface of the body substrate 22 with the cooling device 44, crystallization of the barrier layer 24 can be suppressed. Note that cooling of the outer surface of the body substrate 22 with the cooling device 44 may be continued even in the stage of cooling and solidifying after the heat treatment.

[0032] In the barrier layer forming step, the temperature difference between the inner surface and the outer surface of the body substrate 22 is preferably 10° C. or more and 160° C. or less, more preferably 30° C. or more and 140° C. or less, and even more preferably 90° C. or more and 120° C. or less. This makes it possible to increase the temperature on the inner surface side of the body substrate 22 to promote vaporization of the vaporized components, while lowering the temperature on the outer surface side of the body substrate 22 to suppress deterioration of the body substrate 22.

[0033] The heating temperature in the pre-heating step is preferably higher than the heating temperature in the barrier layer forming step. The heating temperature in the pre-heating step is preferably 230° C. or higher and 255° C. or lower. The heating temperature in the barrier layer forming step is preferably 200° C. or higher and 240° C. or lower. In this way, since the pre-heating step is performed at a temperature higher than the heating temperature in the barrier layer forming step, most of the vaporized components that can be vaporized at the heating temperature when the barrier layer 24 is formed can be vaporized in advance. Therefore, voids generated by heating when the barrier layer 24 is formed can be effectively suppressed.

[0034] The heat treatment in the pre-heating step and the heat treatment in the barrier layer forming step are performed using the same heater 42. This allows the heater 42 to be used for both the pre-heating step and the heat treatment when forming the barrier layer 24. Alternatively, the heater 42 may be kept inserted inside the trunk substrate 22 during the pre-heating step, and the heat treatment in the barrier layer forming step may be performed in this state.

[0035] (Effects of the first embodiment) In the method for manufacturing a pressure vessel of the first embodiment, before the barrier material is applied to the inner surface of the body substrate 22, the vaporized components of the body substrate 22 can be vaporized by a pre-heating process and released to the outside of the body substrate 22. Therefore, in the heat treatment step for forming the barrier layer 24, the amount of vaporized components in the body substrate 22 is reduced, making it possible to suppress the generation of voids at the interface between the body substrate 22 and the barrier layer 24. By suppressing the generation of voids at such an interface, it is possible to expect, for example, improved resistance to hydrogen blistering when filling with hydrogen.

[0036] Furthermore, in the manufacturing method for a pressure vessel of the first embodiment, the heating temperature in the pre-heating treatment is higher than the heating temperature during formation of the barrier layer 24. This makes it possible to pre-vaporize most of the vaporizable components that may be vaporized from the body substrate 22 at the heating temperature during formation of the barrier layer 24. This makes it possible to effectively suppress voids that are generated by heating during formation of the barrier layer 24.

[0037] Furthermore, in the method for producing a pressure vessel of the first embodiment, the preliminary heating process heats both the inner and outer surfaces of the body substrate 22. This allows the body substrate 22 to be heated from both its inner and outer surfaces, so that the vaporization of the vaporized components in the body substrate 22 can be efficiently carried out.

[0038] Furthermore, in the method for manufacturing the pressure vessel of the first embodiment, the pre-heating process and the heat treatment during the formation of the barrier layer 24 are performed using the same heater 42. This allows the heater 42 to be used for both the pre-heating process and the heat treatment during the formation of the barrier layer 24, thereby reducing the manufacturing cost.

[0039] Furthermore, in the method for manufacturing a pressure vessel of the first embodiment, the heating time in the preliminary heating process is longer than the heating time during formation of the barrier layer 24. This makes it easier to suppress deterioration of the barrier layer 24 while sufficiently vaporizing the vaporized components in the body substrate 22.

[0040] Furthermore, in the method for manufacturing a pressure vessel of the first embodiment, the outer surface of the body substrate 22 is cooled during the heat treatment for forming the barrier layer 24. According to this configuration, by cooling the outer surface of the body substrate 22, it is possible to suppress the vaporization of the vaporized components on the outer surface side of the body substrate 22. Therefore, it is possible to reduce the vaporization of the vaporized components in the body substrate 22 as a whole when forming the barrier layer 24, and to suppress the occurrence of voids. <Example>

[0041] Next, the first embodiment will be described more specifically with reference to examples. 1. Sample Preparation A plate-shaped heating object 120 was prepared to resemble the trunk section 20. The heating object 120 includes a base 122 made of carbon fiber reinforced plastic (CFRP) and a barrier material 124 made of EVOH (ethylene-vinyl alcohol copolymer). As shown in Table 1 below, sample No. 1-6 was obtained by subjecting the heating object 120 to a heat treatment under different heating conditions. The base 122 was 80 mm square and 3.0 mm thick. The barrier material 124 was 70 mm square and 1.0 mm thick, and was applied onto the base 122.

[0042] [Table 1]

[0043] 2.Heating method For sample No. 1-2, in the barrier layer formation step, a heating target 120 was subjected to a heat treatment using a thermostatic chamber 130 as shown in FIG. 4. In the thermostatic chamber 130, the base 122 and the barrier member 124 were placed on an aluminum frame 132 in the arrangement shown in FIG. 4. The heating temperature in the thermostatic chamber 130 was 210° C., and the heating time was 100 seconds. For sample No. 1, a pre-heating step was not performed. For sample No. 2, a pre-heating step was performed. The pre-heating treatment for sample No. 2 was performed using the configuration shown in FIG. 4, with a heating temperature of 245° C. and a heating time of 600 seconds.

[0044] For samples No. 3-4, in the barrier layer formation step, the heating target 120 was heated using an infrared heater 140 that radiates far-infrared rays, as shown in Fig. 5. The base 122 and the barrier member 124 were placed on a brick 142 in the arrangement shown in Fig. 5. The infrared heater 140 was abruptly stopped when the temperature reached 230°C during heating. For sample No. 3, a pre-heating step was not performed. For sample No. 4, a pre-heating step was performed. The pre-heating treatment for sample No. 4 was performed using the configuration shown in Fig. 5, with a heating temperature of 240°C and a heating time of 600 seconds.

[0045] For Sample No. 5-6, in the barrier layer formation step, as shown in FIG. 6, the heating target 120 was heated using an infrared heater 140 that radiates far infrared rays and a cooling device 150 that performs reverse surface cooling. In the arrangement shown in FIG. 6, the base 122 and the barrier member 124 were placed on an aluminum plate 152 and thermally conductive grease 154. The infrared heater 140 was stopped abruptly when it reached 230°C during heating. A Peltier device (manufactured by Ohm Electric Co., Ltd., OCE-KT3) was used as the cooling device 150. Sample No. 5 did not undergo a pre-heating step. Sample No. 6 underwent a pre-heating step. The pre-heating step for Sample No. 6 was performed using the configuration shown in FIG. 5, with the heating temperature being 240°C and the heating time being 600 seconds.

[0046] 3. Evaluation method Next, the obtained samples No. 1 to 6 were evaluated as follows.

[0047] [Temperature evaluation method] The temperature in the vicinity of the interface between the barrier member 124 and the base 122 (position X in Figs. 4 to 6) and the temperature on the lower surface of the base 122 (position Y in Figs. 4 to 6) were measured. The measured temperature over time is shown in Figs. 7 to 9. Figs. 7 to 9 show the results for Samples No. 1-2, Samples No. 3-4, and Samples No. 5-6, respectively. Fig. 7 shows the atmospheric temperature over time in the thermostatic chamber 130 and the difference over time between the temperature in the vicinity of the interface between the barrier member 124 and the base 122 and the temperature on the lower surface of the base 122. Figs. 8 and 9 show the surface temperature of the infrared heater 140 over time and the difference over time between the temperature in the vicinity of the interface between the barrier member 124 and the base 122 and the temperature on the lower surface of the base 122.

[0048] [Evaluation method for void ratio and void diameter] After the heat treatment, the entire peeled surface of the barrier member 124 peeled off from the substrate 122 was observed under a microscope, and a representative portion (total screen area: 1.7494 mm 2) was the observation and evaluation range. The evaluation results are shown in Table 1. The "void ratio" in Table 1 is the ratio of the total area of ​​voids contained in the observation and evaluation range to the area of ​​the observation and evaluation range. The "50% distribution value" in Table 1 is the median value when taking the distribution of void diameters (the diameter of voids that accounts for 50% of the number when counted in order of size). Note that voids smaller than 5.6 μm were not measured due to the limits of measurement accuracy.

[0049] [Method of evaluating gas generation] An analysis of gas generated during heating was performed on a member made of carbon fiber reinforced plastic (CFRP) corresponding to the base 122. The results are shown in FIG. 10. FIG. 10 shows the relationship between the vaporized components separated according to boiling point and the amount of vapor generated. The two bar graphs respectively show the results of the first heating process (heating process without pre-heating) and the second heating process (heating process after pre-heating). In the pre-heating, the heating temperature was 230°C and the heating time was 600 seconds. The two line graphs respectively show the cumulative amount of vaporized components generated in the first heating process and the cumulative amount of vaporized components generated in the second heating process.

[0050] 4. Evaluation Results [Temperature evaluation results] In sample No. 1-2, as shown in FIG. 7, when the temperature near the interface between the barrier material 124 and the base 122 (position X in FIG. 4) was 230°C, the temperature on the underside of the base 122 (position Y in FIG. 4) was 232°C, i.e., the temperature on the underside of the base 122 was 2°C higher. In sample No. 3-4, as shown in FIG. 8, when the temperature near the interface between the barrier material 124 and the base 122 (position X in FIG. 7) was 230°C, the temperature on the underside of the base 122 (position Y in FIG. 7) was 193°C, which was 38°C lower. In sample No. 5-6, as shown in FIG. 9, when the temperature near the interface between the barrier material 124 and the base 122 (position X in FIG. 8) was 230°C, the temperature on the underside of the base 122 (position Y in FIG. 8) was 126°C, which was 104°C lower. The temperature of the lower surface side of the substrate 122 of the sample 3-4 heated by the infrared heater 140 was able to be lowered than that of the sample 1-2 heated by the thermostatic bath 130 . In sample No. 5-6, which was not subjected to reverse-face cooling by the cooling device 150, the temperature on the lower surface side of the base 122 could be reduced by about 100° C. compared to sample No. 3-4, which was not subjected to reverse-face cooling.

[0051] In sample No. 5-6, a Peltier device was used as the cooling device, but other cooling devices may also be used. For example, it was confirmed that a cooling device using cooling water (RKS1500F, manufactured by Orion Machinery Co., Ltd., chiller setting 10°C) can lower the temperature of the underside of the base 122 by about 120°C.

[0052] [Evaluation results of generated gas] As shown by the two line graphs in Figure 10, the amount of gas generated in the second heating treatment (heating treatment performed after pre-heating) is about 8 ppm lower than in the first heating treatment (heating treatment without pre-heating). In addition, the amounts of butanediol, 2-ethylhexyl acrylate, polyol compounds, imidazole compounds, butanediol diglycidyl ether, butyl acrylate, and other acrylic compounds are reduced or not detectable in the second heating treatment compared to the first heating treatment. From the above, it can be seen that when pre-heating is performed, it is possible to remove in advance the vaporized components that have a boiling point below the pre-heating temperature.

[0053] [Evaluation results of void ratio and void diameter] In sample No. 1-2, which was subjected to a heat treatment in the thermostatic chamber 130, the void fraction of sample No. 1 was 19.5%, and the void fraction of sample No. 2 was 9.4%. This shows that when the thermostatic chamber 130 was used, the void fraction was reduced by half by performing a pre-heat treatment.

[0054] In sample No. 3-4, which was subjected to a heat treatment using the infrared heater 140, the void ratio of sample No. 3 was 18.9%, and the void ratio of sample No. 4 was 11.2%. This shows that when the infrared heater 140 was used, the void ratio was reduced by half by performing a pre-heat treatment.

[0055] In sample No. 5, which was subjected to heat treatment by the infrared heater 140 and reverse-face cooling, the void fraction was 10.6%, which was lower than the value (18.9%) of sample No. 3, which was not subjected to reverse-face cooling.

[0056] In sample No. 5-6, which was subjected to heat treatment by the infrared heater 140 and reverse-face cooling, the void fraction of sample No. 5 was 10.6%, and the void fraction of sample No. 6 was 2.7%. This shows that when heat treatment was performed by the infrared heater 140 and reverse-face cooling was performed, the void fraction was significantly reduced by performing pre-heat treatment.

[0057] As described above, when pre-heating was performed (in the cases of samples No. 2, No. 4, and No. 6), it is believed that the pre-heating could vaporize the vaporized components of the base 122, as explained in the above section "Evaluation of generated gases." Therefore, when the barrier member 124 was subjected to heat treatment, it is believed that the vaporization of the vaporized components of the base 122 was less likely to occur, and voids were less likely to occur at the interface between the base 122 and the barrier member 124, compared to when pre-heating was not performed (in the cases of samples No. 1, No. 3, and No. 5).

[0058] Furthermore, when reverse-face cooling was performed in the barrier layer formation process (in the case of samples No. 5-6), it is believed that evaporation of the region near the interface could be suppressed by suppressing the temperature rise in the region near the interface inside the substrate 122, and that the occurrence of voids could be suppressed compared to when reverse-face cooling was not performed (in the case of samples No. 3-4).

[0059] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention. (1) In the first embodiment, in the pre-heating step or the barrier layer forming step, heating may be performed with the heater 42 so that the temperature of both end portions in the axial direction of the body substrate 22 is higher than the temperature of the central portion. This makes it possible to heat the end portions of the body substrate 22, which are more likely to release heat, to a higher temperature, making it easier to heat the body substrate 22 uniformly. (2) In the above first embodiment, both the inner and outer surfaces of the body base 22 are heated in the pre-heating treatment, but only the inner surface of the body base 22 may be heated. (3) In the above first embodiment, an example was shown in which the heating temperature in the pre-heating process was higher than the heating temperature in the barrier layer formation process, but it may also be the same as the heating temperature in the barrier layer formation process or lower than the heating temperature in the barrier layer formation process. (4) In the above first embodiment, the heating process in the pre-heating step and the heating process in the barrier layer forming step are performed by the same heater 42. However, different heaters may be used in each step. [Explanation of symbols]

[0060] 10...Pressure vessel 20...Body section 22...Body base (base member) 24...Barrier layer 30…Dome section division body 31...Dome base 40...Pressure vessel manufacturing equipment 42…Heater 44…Cooling device 46...Cooling member 48...Cooler 120…Heated object 122...Base 124...Barrier material 130…Thermostatic oven 132…Aluminum frame 140…Infrared heater 142…Brick 150…Cooling device 152…Aluminum plate L1…Axis line

Claims

1. A method for manufacturing a pressure vessel comprising: a base member having a base material containing a vaporizable component that vaporizes when heated; and a barrier layer formed by heat-treating a barrier material applied to an inner surface of the base member, the method comprising the steps of: Prior to applying the barrier material to the inner surface, a pre-heating process is performed in which the base member is heated to vaporize the vaporized components of the base material. A method for manufacturing a pressure vessel.

2. The heating temperature in the pre-heating treatment is higher than the heating temperature in the formation of the barrier layer. A method for manufacturing the pressure vessel according to claim 1.

3. In the pre-heating treatment, both the inner surface and the outer surface of the base member are heated. A method for producing a pressure vessel according to claim 1 or 2.

4. The pre-heating process and the heat treatment during the formation of the barrier layer are performed using the same heater. A method for producing a pressure vessel according to claim 1 or 2.

5. The heating time in the pre-heating treatment is longer than the heating time in forming the barrier layer. A method for producing a pressure vessel according to claim 1 or 2.

6. The outer surface of the base member is cooled during the heat treatment for forming the barrier layer. A method for producing a pressure vessel according to claim 1 or 2.

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