JP2015140703A - Heat insulation layer structure and manufacturing method for same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate obtaining a heat insulation layer structure low in the surface roughness of a heat insulation layer and high in heat insulation performance, and facilitate controlling the thickness of the heat insulation layer in such a heat insulation layer structure.SOLUTION: A method of manufacturing a heat insulation layer structure comprises the steps of: producing a thin film 40 formed of a material lower in thermal conductivity than a base material; forming a plurality of concave portions 41 in predetermined positions of a surface of the thin film 40; building up a plurality of thin films 40 and forming a multilayer body; disposing the multilayer body on the base material; and firing the multilayer body disposed on the base material. In the step of forming the multilayer body, the thin films 40 are built up so that the concave portions 41 of the thin films 40 directly contact each other do not overlap in a perpendicular direction of the surfaces of the thin films 40.

Description

  The present invention relates to a heat insulating layer structure and a manufacturing method thereof.

  In recent years, it has been important to reduce heat loss in order to improve the thermal efficiency of the engine, and in order to reduce this heat loss, a heat insulating layer is provided on the cylinder head, piston, valve, etc. that form the combustion chamber of the engine. It is being considered.

  Although it is not the heat insulation layer structure in the part which forms the combustion chamber of the said engine, for example, in patent document 1, as the heat insulation layer structure, the heat insulation layer was provided through the bond coating layer on the surface of the turbine blade which is a base material. A structure is disclosed. This heat insulation layer is formed by vapor deposition or the like so that two kinds of materials are alternately arranged. According to Patent Document 1, such a structure provides an improved heat transfer resistance path and has an advantage that the strain tolerance of the heat insulating layer is not impaired.

  Patent Document 2 discloses a structure in which a heat insulating layer including a first heat insulating material made of hollow particles and a second heat insulating material made of solid ceramic or the like is formed. Although the method for forming the heat insulating layer is not clarified, it is generally easy to use application by spraying.

JP 7-504232 A Republished patent WO2009 / 020206

  In Patent Document 1, as described above, an improved heat transfer resistance path can be obtained, which is advantageous in improving the heat insulation performance of the heat insulation layer, but the heat insulation layer is formed by alternately depositing two kinds of materials. Therefore, it is difficult to apply this method to automobile engine parts that are produced in large quantities. In particular, it is extremely difficult to apply to an inner wall portion that forms an internal space such as an exhaust port.

  Moreover, when the heat insulation layer of patent document 2 is apply | coated to a base material using a spray, there exists a possibility that the surface roughness of a heat insulation layer may become large from relationships, such as size distribution of a hollow particle, a compounding quantity. When the surface roughness is large, there is a possibility that a local temperature rise on the surface of the heat insulating layer may occur, which is not preferable. Furthermore, for example, when the heat insulating layer material is applied to the inclined surface of the cavity of the piston, sagging may occur, and it is not easy to control the thickness of the heat insulating layer.

  The present invention has been made in view of the above problems, and an object thereof is to make it possible to easily obtain a heat insulating layer structure having a small surface roughness of the heat insulating layer and high heat insulating performance, The object is to facilitate the control of the thickness of the heat insulating layer in such a heat insulating layer structure.

  In order to achieve the above object, in the present invention, a heat insulating layer structure is manufactured by providing a base material with a heat insulating layer obtained by laminating a plurality of thin films including concave portions at predetermined positions.

  Specifically, the method for manufacturing a heat insulating layer structure according to the present invention is a method for manufacturing a heat insulating layer structure in which a heat insulating layer is formed on the surface of a base material constituting an engine member, and has a thermal conductivity higher than that of the base material. A step of forming a thin film made of a low material, a step of forming a plurality of recesses at predetermined positions on the surface of the thin film, a step of stacking a plurality of thin films to form a laminate, and the laminate on the substrate A step of arranging and a step of firing the laminate disposed on the substrate. In the step of forming the laminate, the plurality of thin films are in contact with each other, and the recesses between the thin films are in contact with each other. It is characterized by being laminated so as not to overlap in the vertical direction.

  According to the method for manufacturing a heat insulating layer structure according to the present invention, a plurality of concave portions are formed in a thin film, a laminate obtained by laminating the thin film is provided on the surface of the base material, and a heat insulating layer is obtained by firing it. Therefore, the thickness of the heat insulating layer can be easily controlled by adjusting the number of laminated thin films or the thickness of the thin film itself. Moreover, since the heat insulation layer is comprised by the laminated body which laminated | stacked the thin film, the surface roughness of a heat insulation layer can be reduced compared with the case where spray coating is used like the said patent document 2. FIG. Furthermore, since the thin films provided with the recesses are stacked, the recesses become a space containing air due to the lamination of the thin films, and the thermal conductivity of this part is lower than the other part of the heat insulating layer. For this reason, the heat from the surface of the heat insulating layer is conducted so as to avoid the space and is transmitted to the base material. That is, since the heat conduction path becomes long, it is advantageous for the heat insulating performance of the heat insulating layer.

  In the method for manufacturing a heat insulating layer structure according to the present invention, in the step of forming the recess, a plurality of recesses are formed on the surface of the thin film so that the recesses are arranged in a triangular lattice shape, and in the step of forming the laminate, It is preferable to laminate a plurality of thin films so that the recesses are arranged in a face-centered cubic lattice.

  If it does in this way, the recessed part used as the space part with especially low thermal conductivity in a heat insulation layer can be arrange | positioned so that a heat conductive path may become long easily. For this reason, a heat insulation layer with high heat insulation performance can be obtained easily.

  In the method for manufacturing a heat insulating layer structure according to the present invention, in the step of forming the laminated body, a thin film made of a material having a lower thermal conductivity than the base material and having no recess is disposed in the uppermost layer of the laminated body. It is preferable to do.

  If it does in this way, since a crevice is not exposed to the uppermost layer of a layered product, an increase in surface roughness of a heat insulation layer resulting from a crevice can be prevented.

  The manufacturing method of the heat insulation layer structure which concerns on this invention may further be equipped with the process of arrange | positioning a hollow particle in a recessed part.

  If it does in this way, since the hollow particle supports the part of the thin film laminated | stacked on the recessed part from the downward direction, it can prevent that the thin film on a recessed part sinks by a combustion load. Furthermore, since the hollow particles are particles containing air inside, the increase in the thermal conductivity in the space can be reduced by disposing them in the recesses.

  It is preferable that the manufacturing method of the heat insulation layer structure which concerns on this invention is further equipped with the process of drying a thin film.

  If it does in this way, the process of forming a crevice can be performed favorably, and handling of a thin film at the time of lamination of a thin film becomes easy, and work efficiency can be improved.

  In the method for manufacturing a heat insulating layer structure according to the present invention, in the step of forming the recess, the pressing member having a protrusion at a position corresponding to a predetermined position on the surface of the thin film forming the recess is pressed against the thin film. It is preferable to form a recess.

  If it does in this way, it will become possible to form a plurality of crevice efficiently and simply.

  The heat insulating layer structure according to the present invention is a heat insulating layer structure in which a heat insulating layer is formed on the surface of a base material constituting an engine member, and includes a first heat conducting portion having a lower thermal conductivity than the base material, And a second heat conduction part having a lower thermal conductivity than the heat conduction part, and the second heat conduction part is arranged in a face-centered cubic lattice shape.

  According to the heat insulating layer structure according to the present invention, heat from the surface of the heat insulating layer is conducted so as to avoid the second heat conductive portion having a lower thermal conductivity provided in a face-centered cubic lattice and is transmitted to the base material. In other words, since the heat conduction path becomes longer, it is advantageous for the heat insulating performance of the heat insulating layer.

  In the heat insulating layer structure according to the present invention, it is preferable that the second heat conducting portion includes air.

  If it does in this way, the thermal conductivity of the 2nd heat conduction part can be made very small. In this case, the 2nd heat conductive part may contain the hollow particle. Even in this case, since the hollow particles contain air inside, the thermal conductivity of the second thermal conductivity can be reduced.

  In the heat insulating layer structure according to the present invention, it is preferable that the second heat conducting portion is not exposed on the surface of the heat insulating layer.

  If it does in this way, when the 2nd heat conduction part is the space part containing air or it contains hollow particles, the increase in the surface roughness of the heat insulation layer resulting from the 2nd heat conduction part can be controlled.

  According to the manufacturing method of the heat insulation layer structure which concerns on this invention, the surface roughness of the heat insulation layer in a heat insulation layer structure can be made small, and control of the thickness of a heat insulation layer can be made easy. In addition, the heat insulating layer structure according to the present invention has a portion having a lower thermal conductivity than the other portions arranged in a face-centered cubic lattice in the heat insulating layer. It becomes possible to improve the heat insulation performance of the layer.

It is sectional drawing which shows the engine structure which concerns on embodiment of this invention. It is sectional drawing which shows the heat insulation layer provided in the engine member surface which concerns on embodiment of this invention. It is a figure for demonstrating the effect of the heat insulation layer which concerns on embodiment of this invention. (A) And (b) is a figure for demonstrating the manufacturing method of the heat insulation layer structure which concerns on embodiment of this invention, (a) is the figure seen from upper direction, (b) is a figure of (a). It is sectional drawing in the AA line. It is a figure for demonstrating the manufacturing method of the heat insulation layer structure which concerns on embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its method of application, or its application.

  In the embodiment of the present invention, the heat insulating layer structure is adopted as a member constituting the combustion chamber of the engine shown in FIG.

<Engine features>
In the direct injection engine E shown in FIG. 1, reference numeral 1 is a piston, reference numeral 3 is a cylinder block, reference numeral 5 is a cylinder head, reference numeral 7 is an intake valve for opening and closing the intake port 9 of the cylinder head 5, and reference numeral 11 is an exhaust port 13. An exhaust valve that opens and closes, reference numeral 15 denotes a fuel injection valve. The combustion chamber of the engine is formed by the top surface of the piston 1, the cylinder block 3, the cylinder head 5, and the valve head surfaces of the intake and exhaust valves 7 and 11. A cavity 17 is formed on the top surface of the piston 1. In FIG. 1, illustration of the spark plug and the cylinder liner is omitted.

  By the way, it is known that the thermal efficiency of an engine increases as the geometric compression ratio increases theoretically and the excess air ratio of the working gas increases (increases the specific heat ratio). However, in practice, as the compression ratio is increased and the excess air ratio is increased, the cooling loss increases. Therefore, the improvement of the thermal efficiency due to the increase in the compression ratio and the excess air ratio reaches its peak.

  That is, the cooling loss depends on the heat transfer rate from the working gas to the engine combustion chamber wall, the heat transfer area, and the temperature difference between the gas temperature and the wall temperature. For this reason, in the engine combustion chamber, a heat insulating layer made of a material having a lower thermal conductivity than the metal base material of the engine component is formed on the surface of the metal base material.

<About heat insulation layer structure>
Next, the heat insulation layer structure of this embodiment in which a heat insulation layer is formed on the surface of a metal base material (base material) of an engine component will be described with reference to FIG. In the present embodiment, a configuration in which a heat insulating layer is formed on the top surface of the piston, which is a member facing the engine combustion chamber, as the metal base material of the engine component will be described. It can also be set as the structure by which the heat insulation layer was formed in the member surface which faces. Moreover, the structure which formed the heat insulation layer in the intake port surface or the exhaust port surface other than the member which faces an engine combustion chamber is also employable. Note that the piston of the present embodiment is made of an aluminum alloy that is subjected to a T6 treatment that is heat-treated at about 180 ° C., for example.

  As shown in FIG. 2, a heat insulating layer 21 is formed on the top surface 1a of a piston (base material) 1 as an engine member. The heat insulating layer 21 includes a first heat conducting part 21a made of silicone resin and a second heat conducting part 21b having a lower thermal conductivity than the first heat conducting part 21a. The material of the first heat conducting portion 21a is not limited to silicone resin, but may be any material that has a lower thermal conductivity than the aluminum alloy that is the material of the piston 1 on which the heat insulating layer 21 is provided. Acid glass or the like may be used.

The second heat conducting part 21b contains hollow particles containing air so that the heat conductivity is lower than that of the first heat conducting part 21a. The hollow particles include Si-based oxide components (for example, silica (SiO ₂ )) or Al-based oxide components (for example, alumina (Al ₂ O ₃ )) such as fly ash balloon, shirasu balloon, silica balloon, and airgel balloon. It is preferable to employ ceramic hollow particles containing. Each material and particle size are as shown in Table 1.

For example, the chemical composition of the fly ash _{balloons, SiO 2; 40.1~74.4%, Al} 2 O 3; 15.7~35.2%, Fe 2 O 3; 1.4~17.5%, MgO; 0.2 to 7.4%, CaO; 0.3 to 10.1% (the above is mass%). The chemical composition of the Shirasu _{balloon, SiO 2; 75~77%, Al} 2 O 3; 12~14%, Fe 2 O 3; 1~2%, Na 2 O; 3~4%, K 2 O; 2~ 4%, IgLoss; 2 to 5% (the above is mass%).

  In the present embodiment, the second heat conducting unit 21b is configured to contain hollow particles, but may be configured only by hollow particles, and the hollow particles and the material of the first heat conducting unit 21a You may be comprised with the mixture with the silicone resin etc. which become. Furthermore, if it is comprised so that heat conductivity may become lower than the 1st heat conduction part 21a, it is not restricted to them, For example, it is good also as a space part containing only air.

  Further, in the heat insulating layer 21 according to the present embodiment, the second heat conducting portions 21b are arranged in a triangular lattice shape in a cross section cut in the vertical direction as shown in FIG. That is, in the heat insulating layer 21, the second heat conducting portions 21b are three-dimensionally arranged in a face-centered cubic lattice shape. With this arrangement, as shown in FIG. 3, the heat received by the surface of the heat insulating layer 21 is conducted so as to avoid the second heat conducting portion 21b having a lower thermal conductivity. The heat conduction path becomes longer than when the conductive portion is not arranged. That is, the heat insulation performance of the heat insulation layer 21 is improved.

  Further, the second heat conducting part is configured not to be exposed on the surface of the heat insulating layer 21. For this reason, the increase in the surface roughness of the heat insulation layer 21 resulting from the hollow particle which comprises the 2nd heat conductive part 21b can be suppressed.

<Production method of heat insulation layer structure>
Next, the manufacturing method of the heat insulation layer structure which concerns on embodiment of this invention is demonstrated, referring FIG. 4 (a) and (b) and FIG. Fig.4 (a) is the figure which looked at the conveyor apparatus for manufacturing a heat insulation layer structure from upper direction, FIG.4 (b) is sectional drawing in the AA line of Fig.4 (a). FIG. 5 is a cross-sectional view showing one step of the method for manufacturing the heat insulating layer structure.

  In the present embodiment, a method for manufacturing a heat insulation layer using a conveyor device 50 as shown in FIGS. 4A and 4B will be described. The conveyor device 50 has a base sheet 51 disposed thereon, and is configured to be able to move the base sheet in one direction (the left direction in FIGS. 4A and 4B, hereinafter referred to as the conveyor flow direction). ing. In addition, a resin material 40 a serving as a material of the first heat conducting portion 21 a is filled above the conveyor device 50, and a resin material discharge device 52 configured to be able to discharge a resin material, and the resin material discharge device 52. A block-shaped pressing member having a blade 53 for making the discharged resin material 40a have a predetermined thickness by a doctor blade method and a plurality of protrusions 54a protruding downward and movable in the vertical direction. A stamper 54 and a hollow particle discharge device 55 filled with the hollow particles 42 and configured to discharge the hollow particles are sequentially arranged in the conveyor flow direction.

  In the manufacturing method of the heat insulation layer structure according to the present embodiment, first, the resin material 40a is discharged from the resin material discharge device 52 disposed above the conveyor device 50, and the resin material 40a is provided on the surface of the base sheet 51. . As the resin material 40a, for example, a silicone resin material, particularly polyalkylphenylsiloxane or the like can be used. The resin material 40a disposed on the base sheet 51 is moved in the conveyor flow direction, and the resin material is formed into a thin film 40 having a desired film thickness by a doctor blade method using a blade 53. Therefore, the blade 53 is disposed so that the distance between the lower end portion of the blade 53 and the base sheet 51 is a desired film thickness. The film thickness of the thin film 40 is, for example, about 20 μm to 60 μm.

  Next, a stamper 54 having a plurality of protrusions 54 a on the surface of the thin film 40 is pressed against the thin film 40 to form a plurality of recesses 41 on the surface of the thin film 40. Here, it is preferable that the plurality of recesses 41 are provided at predetermined intervals. For this reason, the stamper 54 is preferably provided with a plurality of protrusions 54a at a predetermined interval. In particular, the plurality of recesses 41 are preferably provided so as to be arranged in a triangular lattice shape. That is, it is preferable that the protrusions 54a of the stamper 54 are arranged in a triangular lattice shape.

  Moreover, it is preferable that the depth of the recessed part 41 is about 1/2 or more and 3/4 or less of the thickness of the thin film 40. FIG. If it does in this way, the magnitude | size of the part which becomes a 2nd heat conductive part later can fully be ensured, maintaining the intensity | strength of the thin film 40. FIG. In the present embodiment, the concave portion 41 is formed in the thin film 40 using the block-shaped stamper 54 having the protruding portion 54a. However, the present invention is not limited thereto. For example, the roller 41 having the protruding portion is rotated while being pressed against the thin film 40. The recess 41 may be formed. Moreover, not only the method of providing the recessed part 41 by pressing a projection part as mentioned above to the thin film 40 but the recessed part 41 may be formed by irradiating the thin film 40 with a laser or an ion beam, for example.

  In addition, you may add the process of drying the thin film 40 before the process of forming this recessed part 41. FIG. By doing in this way, the recessed part 41 can be favorably molded by the stamper 54 of the thin film 40. The drying method is not particularly limited. For example, the thin film 40 can be dried by providing a heating means such as a heater between the blade 53 and the stamper 54. This drying is preferably performed at a temperature equal to or lower than the firing temperature, and may be performed to such an extent that the handling properties of each thin film 40 can be improved.

  Next, the hollow particles 42 are accommodated in the plurality of formed recesses 41. In this embodiment, the hollow particles 42 are accommodated in the recesses 41 by discharging the hollow particles 42 from the hollow particle discharge device 55 filled with the hollow particles 42 into the recesses 41. Here, in the hollow particle discharge device 55, a plurality of discharge ports for discharging the hollow particles 42 are provided, and are arranged so as to correspond to the plurality of recesses 41, that is, the positions of the protrusions 54a of the stamper 54. It is arranged to correspond to. For this reason, the hollow particles 42 can be accommodated in the plurality of recesses 41 by a single discharge operation. Further, the hollow particles 42 may be filled in the hollow particle discharge device 55 in a state of being mixed with a solvent or a binder material, and may be accommodated in the concave portion 41 in the state of the mixture. The particle size of the hollow particles 42 may be selected in consideration of the depth and width of the recess 41, or may be selected to a preferable size by classification operation.

  After the hollow particles 42 are accommodated in the recesses 41, the thin film 40 is cut into a predetermined size. Thereafter, as shown in FIG. 5, three cut thin films 40 are laminated. Here, three thin films 40 are stacked, but the number of thin films 40 to be stacked can be determined as appropriate according to the desired thickness of the heat insulating layer. When the thin film 40 is laminated, the concave portions 41 in which the hollow particles 42 are accommodated in the thin film 40 are laminated so as not to overlap the concave portions 41 in the upper and lower thin films 40 that are in direct contact with each other in the vertical direction of the surface of the thin film 40. . That is, when three thin films 40 are stacked as shown in FIG. 5, the intermediate film recesses 41 are stacked so that they do not overlap with the upper and lower film recesses 41 in the vertical direction. Further, when the concave portions 41 are arranged in a triangular lattice shape as described above, the thin film 40 can be laminated so that the concave portions 41 are three-dimensionally arranged in a face-centered cubic lattice shape. Further, the uppermost film 43 having no recess 41 is laminated on the uppermost layer of the laminated thin films 40 to obtain a laminated body. By doing in this way, the increase in the surface roughness of the heat insulation layer resulting from the recessed part 41 and the hollow particle 42 accommodated in it can be suppressed. The material of the uppermost film 43 is the same as that of the thin film 40.

  Next, said laminated body is stuck on the surface of base materials, such as a piston. At this time, the laminate can be satisfactorily adhered to the surface of the substrate by using, for example, a silane coupling agent. Thereafter, by firing the laminated body, the thin films 40 and the uppermost film 43 constituting the laminated body are integrated into the first heat conducting portion, and the concave portion 41 including the hollow particles becomes the second heat conducting portion, and as a result. A heat insulating layer having high heat insulating performance as shown in FIG. 2 can be obtained.

  In this embodiment, the conveyor device 50 is used as described above, and the heat insulating layer structure is formed using a device in which the base sheet 51, the resin material discharge device 52, the blade 53, the stamper 54, and the hollow particle discharge device 55 are disposed above the conveyor device 50. However, as long as a thin film having a plurality of recesses can be formed, stacked, and fired, the present invention is not limited to the above manufacturing method.

  According to the manufacturing method of the heat insulation layer structure concerning this embodiment, since the heat insulation layer is produced with the laminated body obtained by laminating | stacking a thin film, control of the thickness of a heat insulation layer can be made easy. Moreover, since the thin film which does not have a recessed part is provided in the uppermost layer of a laminated body, the surface roughness of the heat insulation layer obtained can be made small compared with the surface roughness of the heat insulation layer formed by spray application. Is possible. Further, there is no occurrence of sagging of the coating film as in the case of spray coating on an inclined surface or a vertical surface. Furthermore, the thin film is provided with a recess, and when forming a laminate, the recesses in the upper and lower thin films that are in direct contact with each other are stacked so as not to overlap the vertical direction of the surface of the thin film. The heat from the surface of the layer is conducted so as to avoid the portion where the concave portion is disposed, and is transmitted to the base material. Therefore, since a heat conduction path becomes long, as a result, a heat insulation layer structure with high heat insulation performance can be obtained.

DESCRIPTION OF SYMBOLS 1 Piston 1a Top surface 21 Heat insulation layer 21a 1st heat conduction part 21b 2nd heat conduction part 40 Thin film 40a Resin material 41 Recessed part 42 Hollow particle 43 Top film 50 Conveyor apparatus 51 Base sheet 52 Resin material discharge apparatus 53 Blade 54 Stamper 55 Hollow Particle ejection device

Claims (10)

A method for manufacturing a heat insulating layer structure in which a heat insulating layer is formed on the surface of a base material constituting an engine member,
Producing a thin film made of a material having lower thermal conductivity than the substrate;
Forming a plurality of recesses at predetermined positions on the surface of the thin film;
Laminating a plurality of the thin films to form a laminate;
Disposing the laminate on the substrate;
And firing the laminate disposed on the substrate,
In the step of forming the laminated body, the plurality of thin films are laminated so that the concave portions of the thin films that are in direct contact with each other do not overlap each other in the vertical direction of the thin film surface. In the step of forming the recesses, the plurality of recesses are formed on the surface of the thin film so that the recesses are arranged in a triangular lattice shape,
2. The method for manufacturing a heat insulating layer structure according to claim 1, wherein in the step of forming the stacked body, the plurality of thin films are stacked such that the plurality of concave portions are arranged in a face-centered cubic lattice.   In the step of forming the laminate, a thin film made of a material having a lower thermal conductivity than the base material and not having the recesses is disposed on the uppermost layer of the laminate. The manufacturing method of the heat insulation layer structure of 1 or 2.   The manufacturing method of the heat insulation layer structure of any one of Claims 1-3 further equipped with the process of arrange | positioning a hollow particle in the said recessed part.   The method for producing a heat insulating layer structure according to claim 1, further comprising a step of drying the thin film.   In the step of forming the recess, the recess is formed in the thin film by pressing a pressing member having a protrusion at a position corresponding to a predetermined position on the surface of the thin film forming the recess. The manufacturing method of the heat insulation layer structure of any one of Claims 1-5 characterized by these. A heat insulating layer structure in which a heat insulating layer is formed on the surface of the base material constituting the engine member,
A first thermal conduction part having a lower thermal conductivity than the base material;
A second thermal conduction part having a lower thermal conductivity than the first thermal conduction part,
The heat insulating layer structure characterized in that the second heat conducting part is arranged in a face-centered cubic lattice shape.   The heat insulation layer structure according to claim 7, wherein the second heat conducting unit includes air.   The heat insulation layer structure according to claim 7 or 8, wherein the 2nd heat conduction part contains hollow particles. The heat insulation layer structure according to any one of claims 7 to 9, wherein the second heat conduction part is not exposed on a surface of the heat insulation layer.

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