Aluminum fiber structure and aluminum composite

Abstract

An aluminum composite (1, 2, 3, 4, 5) is a material obtained by combining an aluminum fiber structure (10) and a composite material (70, 80, 110). Aluminum fibers (20) of the aluminum fiber structure (10) are partially bonded to each other, and an aluminum oxide layer (30) is formed on surfaces of the aluminum fibers (20). A plurality of protrusions (40) of aluminum oxide having a height greater than a thickness of the aluminum oxide layer (30) are formed on surfaces of the aluminum fibers (20) or the aluminum oxide layer (30). The protrusions (40) of aluminum oxide are in contact with at least a portion of the composite material (70, 80, 110).

Description

TECHNICAL FIELD

[0001] The present application relates to an aluminum fiber structure and an aluminum composite material. BACKGROUND

[0002] In the past, there has been a case where a metal fiber structure formed of metal fibers is used as a medium that performs heat transfer in a heat exchanger. Japanese Patent Laying-Open No. JP 2011-007365 A shows an example where an aluminum fiber structure formed of aluminum fibers is used as the metal fiber structure.

[0003] The aluminum fiber structure disclosed in Japanese Patent Laying-Open No. JP 2011-007365 A is manufactured by filling aluminum fibers having an average fiber thickness of 50 to 200 μm and an average fiber length of 20 to 1000 mm in a mold of a prescribed shape, forming a compression-molded body having a bulk density of 30% or more by compressing the filled aluminum fibers, forming a porous sintered body by diffusively joining the entangled aluminum fibers by heating the compression-molded body at 600 to 650°C in a non-reactive gas atmosphere, and then hydrophilizing the surface of the aluminum fibers. SUMMARY

[0004] The aluminum fiber structure disclosed in Japanese Patent Laying-Open No. JP 2011-007365 A has a large linear expansion coefficient, and thus in the case of being combined with, for example, glass or ceramic, which have a small linear expansion coefficient, there is a possibility that peeling occurs due to the difference in the linear expansion coefficients of the two when the temperature of the surrounding environment greatly changes.

[0005] The present application has been made in view of the above problems, and has an object to provide an aluminum fiber structure having a small linear expansion coefficient and an aluminum composite material in which peeling is difficult to occur between the aluminum fiber structure and a composite material even when the temperature of the surrounding environment greatly changes.

[0006] Means for solving the problems

[0007] The aluminum fiber structure of the present application is characterized in that

[0008] the aluminum fibers are locally joined to each other,

[0009] an aluminum oxide layer is formed on the surface of the aluminum fibers,

[0010] a plurality of protrusions of aluminum oxide are formed on the surface of the aluminum fibers or the aluminum oxide layer, and the height of the protrusions is greater than the thickness of the aluminum oxide layer.

[0011] The aluminum composite material of the present application is characterized in that

[0012] an aluminum composite material,

[0013] The protrusions of the aluminum oxide are in contact with at least a portion of the composite material. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic configuration diagram schematically showing a first example of a configuration of an aluminum composite material of an embodiment of the present application.

[0015] Figure 2 is a schematic configuration diagram schematically showing a second example of a configuration of an aluminum composite material of an embodiment of the present application.

[0016] Figure 3 is a schematic configuration diagram schematically showing a third example of a configuration of an aluminum composite material of an embodiment of the present application.

[0017] Figure 4 is a schematic configuration diagram schematically showing a fourth example of a configuration of an aluminum composite material of an embodiment of the present application.

[0018] Figure 5 is a schematic configuration diagram schematically showing a fifth example of a configuration of an aluminum composite material of an embodiment of the present application.

[0019] Figure 6 is a photograph taken of a surface of an aluminum fiber structure of an aluminum composite material of an embodiment of the present application.

[0020] Figure 7 is a photograph showing a cross section when the aluminum fiber structure shown in Figure 6 is cut.

[0021] Figure 8 is a photograph showing a portion of a cross section of the aluminum fiber structure shown in Figure 7 enlarged.

[0022] Figure 9 is an explanatory diagram schematically showing a manufacturing method of an aluminum fiber structure of an aluminum composite material of an embodiment of the present application. DETAILED DESCRIPTION

[0023] Embodiments of the present application will be described below with reference to the accompanying drawings. Figures 1 to 5 is a schematic configuration diagram schematically showing a plurality of examples of a configuration of an aluminum composite material of an embodiment of the present application. In addition, Figure 6 is a photograph taken of a surface of an aluminum fiber structure of an aluminum composite material of the present embodiment. In addition, Figure 7 is a photograph showing a cross section when the aluminum fiber structure shown in Figure 6 is cut, Figure 8 is a photograph showing a portion of a cross section of the aluminum fiber structure shown in Figure 7A magnified photograph showing a portion of the cross-section of the aluminum fiber structure shown. Additionally, Figure 9 This is an explanatory diagram schematically illustrating the manufacturing method of the aluminum fiber structure of the aluminum composite material according to this embodiment.

[0024] The aluminum composite materials 1, 2, 3, 4, and 5 in this embodiment are materials formed by combining aluminum fiber structure 10 with composite materials, wherein the composite materials are composed of materials different from aluminum. Figures 1 to 5 This section describes several examples of such aluminum composite materials, 1, 2, 3, 4, and 5.

[0025] like Figure 1 As shown, in the first example of the aluminum composite material 1, resin 70 is completely impregnated within the aluminum fiber structure 10. The material of the resin 70 is not particularly limited; examples include epoxy resin, polyolefin, styrene-based polymer, polyether, polyurea, acrylic polymer, polyurethane, polyester, polyamide, polysiloxane, polysaccharide, peptide, polynucleotide, polyvinyl alcohol, polyacrylamide, and mixtures thereof. Specifically, by completely impregnating the two aluminum fiber structures 10 with resin 70, the aluminum fiber structures 10 are positioned near the surface and back sides of the resin 70. It should be noted that the aluminum fiber structures 10 do not protrude outwards from the surface or back side of the resin 70.

[0026] like Figure 2 As shown, in the second example of aluminum composite material 2, resin 70 is partially impregnated in the aluminum fiber structure 10. Specifically, by partially impregnating the two aluminum fiber structures 10 with resin 70, the aluminum fiber structures 10 protrude outward from the surface and back of the resin 70 at the locations near the surface and back of the resin 70, respectively.

[0027] like Figure 3 As shown, in the third example of aluminum composite material 3, two aluminum fiber structures 10 are bonded together by an adhesive layer 80 composed of an adhesive other than aluminum, such as silver paste, copper paste, nickel paste, silver brazing filler metal, copper brazing filler metal, tin, solder, etc.

[0028] like Figure 4 As shown, in the fourth example of aluminum composite material 4, a metal component 90 such as a copper plate is bonded to a surface of an aluminum fiber structure 10 by an adhesive layer 80 composed of an adhesive such as a metal paste other than aluminum.

[0029] like Figure 5As shown, as an aluminum composite material 4 of the 5th example, a metal member 90 is adhered to one surface of the aluminum fiber structure 10 by an adhesive layer 80 composed of an adhesive such as a metal paste other than aluminum, and an alumina plate 100 is adhered to the other surface of the aluminum fiber structure 10 by an adhesive layer 110 composed of an adhesive such as a glass (e.g., water glass, sintered glass, glass paste).

[0030] Next, the constitution of the aluminum fiber structure 10 will be described. As shown in FIG. 1, the aluminum fiber structure 10 of the present embodiment is one in which aluminum fibers 20 are locally bonded to each other, and an alumina layer 30 is formed on the surface of the aluminum fibers 20. In addition, as shown in FIG. 2, on the surface of the aluminum fibers 20 or the alumina layer 30, a plurality of alumina protrusions 40 having a height greater than the thickness of the alumina layer 30 are formed. Figures 6 to 8 Figure 8 Figure 8

[0031] In such an aluminum fiber structure 10, the portion in which the alumina layer 30 is formed is likely to expand or contract due to temperature changes, whereas the portion in which the plurality of alumina protrusions 40 are formed is less likely to expand or contract due to temperature changes. In this way, in the entire aluminum fiber structure 10, since there is a local deviation in the linear expansion coefficient, the linear expansion coefficient as a whole can be reduced.

[0032] The length of the aluminum fibers 20 is in the range of 0.2 to 15 mm, and the diameter is in the range of 0.01 to 0.100 mm. The length of the aluminum fibers 20 can be confirmed by actual measurement using a photograph observation with a SEM, an optical microscope, or the like.

[0033] The alumina layer 30 is formed by oxidizing the aluminum fibers 20 in an atmospheric atmosphere. The alumina layer 30 is formed substantially uniformly on the surface of the aluminum fibers 20. The thickness of such an alumina layer 30 is in the range of 10 nm to 10 μm, preferably 100 nm to 7 μm, and further preferably 1 μm to 5 μm.

[0034] The protrusions 40 are formed of a substance that is exuded from the aluminum fibers 20 by sintering the aluminum fibers 20 at 700°C or higher. The method of sintering the aluminum fibers 20 to produce the aluminum fiber structure 10 will be described later. Note that in the case where the sintering temperature for the aluminum fibers 20 is less than 700°C, a sufficient amount of alumina is not exuded from the aluminum fibers 20, and protrusions 40 of a sufficient height cannot be obtained.

[0035] ​​​In addition, as described above, the height of the protrusions 40 from the surface of the aluminum fibers 20 or the alumina layer 30 is greater than the thickness of the alumina layer 30. Specifically, the height of the protrusions 40 from the surface of the aluminum fibers 20 or the alumina layer 30 is in the range of 10 nm to 10 μm, preferably 100 nm to 7 μm, and further preferably 1 μm to 5 μm. Thus, the adhesion strength of the aluminum fibers 20 to the protrusions 40 is increased. Here, in the case where the height of the protrusions 40 from the surface of the aluminum fibers 20 or the alumina layer 30 is too small, specifically, less than 10 nm, the difference between the thickness of the alumina layer 30 and the height of the protrusions 40 is not large, and there is a problem in that it is not possible to form a local coefficient of linear expansion deviation in the aluminum fiber structure 10. In addition, in the case where the height of the protrusions 40 from the surface of the aluminum fibers 20 or the alumina layer 30 is too large, specifically, greater than 10 μm, there is a problem in that a large gap is formed between the aluminum fibers 20.

[0036] In Figure 7 and Figure 8 In the cross section of the aluminum fiber structure 10 shown in FIG. 1, the coverage ratio of the portions of the surface of the aluminum fibers 20 covered by the protrusions 40 is preferably 20% or more, and further preferably 40% or more. The surface of the aluminum fibers 20 is substantially entirely covered by the alumina layer 30, and the protrusions 40 are formed locally on the alumina layer 30. The coverage ratio of the portions of the surface of the aluminum fibers 20 covered by the protrusions 40 can be calculated by dividing the length of the alumina layer 30 covered by the protrusions 40 (specifically, the portion of the protrusions 40 from the point at which the peak portion of the protrusion 40 begins to rise to the point at which the peak portion of the protrusion 40 ends to descend) by the entire length of the alumina layer 30 in the cross section of the aluminum fiber structure 10. In the case where the coverage ratio of the protrusions 40 on the surface of the aluminum fibers 20 is less than 20%, the proportion of the protrusions 40 in the aluminum fiber structure 10 is small, and thus there is a problem in that the coefficient of linear expansion of the aluminum fiber structure 10 is not reduced.

[0037] In addition, at least some of the plurality of protrusions 40 span and contact the alumina layers 30 of a plurality of aluminum fibers 20. In this case, since the aluminum fibers 20 are connected to each other by the protrusions 40, it is difficult for the aluminum fibers 20 to move relative to each other, and thus the coefficient of linear expansion of the aluminum fiber structure 10 can be further reduced. In addition, when the aluminum fiber structure 10 is combined with a composite material (for example, the resin 70, the adhesive layer 80, the adhesive layer 110, or the like described above), the composite material that enters the gaps of the aluminum fiber structure 10 contacts the protrusions 40.

[0038] Furthermore, in this embodiment, the fill factor of the aluminum fibers 20 in the aluminum fiber structure 10 is in the range of 20% to 90%. This fill factor of the aluminum fibers 20 can be calculated by measuring the ratio of the area occupied by the aluminum fibers 20 to the area of ​​the inner side of the outer edge of the aluminum fiber structure 10 in the cut surface when the aluminum fiber structure 10 is cut. By having a fill factor of 20% to 90% for the aluminum fibers 20 in the aluminum fiber structure 10, both lightweight and strength can be achieved. Specifically, when the fill factor of the aluminum fibers 20 in the aluminum fiber structure 10 is less than 20%, sufficient strength cannot be obtained; conversely, when the fill factor of the aluminum fibers 20 in the aluminum fiber structure 10 is greater than 90%, lightweighting cannot be achieved. Furthermore, when the fill factor of the aluminum fibers 20 in the aluminum fiber structure 10 is 20% or more, adequate homogeneity can be obtained due to the sufficient amount of aluminum fibers 20. Furthermore, if the fill factor of the aluminum fiber 20 in the aluminum fiber structure 10 is less than 90%, not only can moderate homogeneity be obtained, but also the desired flexibility can be obtained.

[0039] Furthermore, in the aluminum fiber structure 10 of this embodiment, an anti-plasma layer may also be formed on the surfaces of the alumina layer 30 and the protrusions 40. In this case, the anti-plasma layer may also contain metal oxides or aluminum nitride. The metal oxides include, for example, at least one of zirconium oxide, yttrium oxide, magnesium oxide, zinc oxide, sapphire, and quartz glass. In this case, a composite material of the aluminum fiber structure 10 and the anti-plasma layer can be provided, and the composite material exhibits excellent plasma resistance. Such a composite material of the aluminum fiber structure 10 and the anti-plasma layer can be manufactured by coating the alumina layer 30 and the protrusions 40 of the aluminum fiber structure 10 with a ceramic enamel containing zirconium oxide, yttrium oxide, etc., followed by high-temperature heating.

[0040] like Figure 9 As shown in (a), aluminum fibers 20 are formed into a sheet shape inside the forming container 50 and then pressed. This allows the aluminum fibers 20 to be tightly packed together. Furthermore, as... Figure 9 As shown in (b), the aluminum fiber 20 is sintered by heating it at 700°C or higher inside the sintering apparatus 60. This forms the aluminum fiber structure 10. It should be noted that methods for heating the aluminum fiber 20 include heating its surface with hot air, but this method is not limited to this. Electrical heating can also be used. Furthermore, as described above, if the aluminum fiber 20 is sintered at 700°C or higher, alumina melts and precipitates from the aluminum fiber 20, and the precipitated alumina solidifies at room temperature to form protrusions 40. Additionally, by placing the aluminum fiber structure 10 in an atmospheric atmosphere, the aluminum fiber 20 oxidizes to form an alumina layer 30.

[0041] In summary, according to the aluminum fiber structure 10 of the present embodiment, the aluminum fibers 20 are locally bonded to each other, and an aluminum oxide layer 30 is formed on the surface of the aluminum fibers 20. In addition, a plurality of protrusions 40 of aluminum oxide having a height greater than the thickness of the aluminum oxide layer 30 are formed on the surface of the aluminum fibers 20 or the aluminum oxide layer 30. In such an aluminum fiber structure 10, the portions where the aluminum oxide layer 30 is formed are easily expanded or shrunk due to temperature changes, whereas the portions where the plurality of protrusions 40 of aluminum oxide are formed are difficult to expand or shrink due to temperature changes, and thus the linear expansion coefficient locally varies throughout the aluminum fiber structure 10, and the linear expansion coefficient as a whole can be reduced.

[0042] In addition, according to such aluminum composites 1, 2, 3, 4, 5 composed of the aluminum fiber structure 10 and a composite material (for example, the resin 70, the adhesive layer 80, the adhesive layer 110, and the like) different from aluminum, the protrusions 40 of aluminum oxide are in contact with at least a portion of the composite material. Even in the case where the temperature of the surrounding environment greatly changes, peeling between the aluminum fiber structure 10 and the composite material is difficult to occur. In more detail, the composite material that enters the gap of the aluminum fiber structure 10 is hooked on the protrusions 40 of the aluminum fiber structure 10, and thus even the composite material that is difficult to be bonded to aluminum can firmly bond the aluminum fiber structure 10 to the composite material.

[0043] For example, in the aluminum composite 1 of the first and second examples, the resin 70 that enters the gap of the aluminum fiber structure 10 is hooked on the protrusions 40 of the aluminum fiber structure 10, and thus even in the case where the resin 70 is difficult to be bonded to aluminum, the aluminum fiber structure 10 can be firmly bonded to the resin 70.

[0044] In addition, according to the aluminum composites 3, 4 of the third and fourth examples, the adhesive that enters the gap of the aluminum fiber structure 10 is hooked on the protrusions 40 of the aluminum fiber structure 10, and thus the aluminum fiber structure 10 can be firmly bonded to the adhesive layer 80. Thus, in the aluminum composite 3 of the third example, the two aluminum fiber structures 10 are difficult to peel from each other. In addition, in the aluminum composite 4 of the fourth example, the aluminum fiber structure 10 is difficult to peel from the metal member 90 such as a copper plate. In addition, even in the case where the adhesion between the metal member 90 and the adhesive layer 80 is weak, since the linear expansion coefficient of the aluminum fiber structure 10 is small, even if the metal member 90 expands, the aluminum fiber structure 10 is difficult to peel from the metal member 90.

[0045] Further, according to the aluminum composite material 5 of Example 5, the adhesive entering the gap of the aluminum fiber structure 10 is hooked to the protrusions 40 of the aluminum fiber structure 10, whereby the aluminum fiber structure 10 can be firmly adhered to the adhesive layers 80, 110, respectively. Thus, the aluminum fiber structure 10 is difficult to peel from the metal member 90 and the alumina plate 100, respectively. In this case, even if there is a difference in linear expansion coefficient between the metal member 90 and the alumina plate 100, since the linear expansion coefficient of the aluminum fiber structure 10 is small, peeling is difficult to occur between the metal member 90 and the aluminum fiber structure 10 and between the alumina plate 100 and the aluminum fiber structure 10 in the entire aluminum composite material 5.

[0046] Example

[0047] The present application will be described in more detail below using examples and comparative examples.

[0048] Example 1

[0049] The aluminum fiber structure was manufactured according to the following procedure. First, a plurality of aluminum fibers having a material of A1070, a fiber diameter of 50 μm, and an average length of 2 mm were formed into a thin sheet. Then, the aluminum fibers were heated at 700°C inside a sintering apparatus to be sintered. Thus, the aluminum fiber structure was prepared.

[0050] The cut surface when the prepared aluminum fiber structure was cut was confirmed by a microscope, and it was found that an alumina layer was formed on the surface of the aluminum fiber, and a plurality of alumina protrusions having a height greater than the thickness of the alumina layer were formed on the surface of the alumina layer or the aluminum fiber. Further, in the cross section of the aluminum fiber structure, the total coverage of the alumina layer and the protrusions in the surface of the aluminum fiber was 24%, and the packing factor of the aluminum fiber in the aluminum fiber structure was 75%. The respective physical values of such an aluminum fiber structure are shown in Table 1 below.

[0051] Examples 2 to 4

[0052] The aluminum fiber structure was prepared by the same method as Example 1 except that the aluminum fibers were heated at 750°C, 800°C, and 850°C, respectively, inside the sintering apparatus to be sintered. The cut surface when the prepared aluminum fiber structures of Examples 2 to 4 were cut was confirmed by a microscope, and it was found that an alumina layer was formed on the surface of the aluminum fiber, and a plurality of alumina protrusions having a height greater than the thickness of the alumina layer were formed on the surface of the alumina layer or the aluminum fiber. The respective physical values of the prepared aluminum fiber structures of Examples 2 to 4 are shown in Table 1 below.

[0053] Examples 5 to 8

[0054] An aluminum fiber structure was produced by the same method as in Example 1, except that the respective fiber diameters and average lengths of the plurality of aluminum fibers were set to the values shown in Table 1, and the aluminum fibers were heated to sinter at the temperature (800°C or 900°C) shown in Table 1 inside a sintering apparatus. The cut surface when the produced aluminum fiber structure of Example 5 to 8 was cut was confirmed with a microscope, and it was found that an aluminum oxide layer was formed on the surface of the aluminum fiber, and a plurality of protrusions of aluminum oxide having a height greater than the thickness of the aluminum oxide layer were formed on the surface of the aluminum oxide layer or the aluminum fiber. The respective physical property values of the produced aluminum fiber structure of Example 5 to 8 are shown in Table 1 below.

[0055] <Example 9>

[0056] An aluminum fiber structure was produced by the same method as in Example 1, except that the respective fiber diameters and average lengths of the plurality of aluminum fibers were set to the values shown in Table 1, and the aluminum fibers were heated to sinter at the temperature (800°C or 900°C) shown in Table 1 inside a sintering apparatus. The cut surface when the produced aluminum fiber structure of Example 5 to 8 was cut was confirmed with a microscope, and it was found that an aluminum oxide layer was formed on the surface of the aluminum fiber, and a plurality of protrusions of aluminum oxide having a height greater than the thickness of the aluminum oxide layer were formed on the surface of the aluminum oxide layer or the aluminum fiber. The respective physical property values of the produced aluminum fiber structure of Example 5 to 8 are shown in Table 1 below.

[0057] <Example 10>

[0058] An aluminum fiber structure was produced by the same method as in Example 1, except that the respective fiber diameters and average lengths of the plurality of aluminum fibers were set to the values shown in Table 1, and the aluminum fibers were heated to sinter at the temperature (800°C or 900°C) shown in Table 1 inside a sintering apparatus. The cut surface when the produced aluminum fiber structure of Example 5 to 8 was cut was confirmed with a microscope, and it was found that an aluminum oxide layer was formed on the surface of the aluminum fiber, and a plurality of protrusions of aluminum oxide having a height greater than the thickness of the aluminum oxide layer were formed on the surface of the aluminum oxide layer or the aluminum fiber. The respective physical property values of the produced aluminum fiber structure of Example 5 to 8 are shown in Table 1 below.

[0059] <Comparative Examples 1 to 2>

[0060] The aluminum fiber structure bodies of Comparative Examples 1 to 2 were produced by the same method as in Example 1, except that the aluminum fibers were sintered by heating at 680°C and 600°C, respectively, in the interior of a sintering apparatus. The cut surface when the produced aluminum fiber structure bodies of Comparative Examples 1 to 2 were cut was confirmed with a microscope, and it was found that an aluminum oxide layer was formed on the surface of the aluminum fibers, but no protrusions of aluminum oxide were formed on the aluminum oxide layer or the surface of the aluminum fibers. The values of the physical properties of the produced aluminum fiber structure bodies of Comparative Examples 1 to 2 are shown in Table 1 below.

[0061] <Comparative Example 3>

[0062] As Comparative Example 3, a plate-shaped body of aluminum having a material of A1070 was used.

[0063] <Evaluation>

[0064] The linear expansion coefficient at 40°C was measured for the aluminum fiber structure bodies of Examples 1 to 10 and Comparative Examples 1 to 3. The results of the investigation are shown in Table 1 and Table 2 below. Note that in Table 1 and Table 2, the coverage rate is the coverage rate of the protruding portions in the surface of the aluminum fibers in the cross section when the aluminum fiber structure body is cut, and is calculated by dividing the length of the aluminum oxide layer of the portion covered by the protrusions (specifically, the portion from the point at which the peak of the protrusion begins to rise to the point at which it ends to descend) by the total length of the aluminum oxide layer in the cross section of the aluminum fiber structure body. Note that in Comparative Examples 1 to 3, the coverage rate was 0%, which indicates that no protrusions of aluminum oxide were formed. In addition, in Table 1 and Table 2, the packing factor is the packing factor of the aluminum fibers in the aluminum fiber structure body, and is taken as the proportion of the area occupied by the aluminum fibers in the cut surface when the aluminum fiber structure body is cut, relative to the area inside the outer edge of the aluminum fiber structure body.

[0065] [Table 1]

[0066]

[0067] [Table 2]

[0068]

[0069] The cut surfaces of the aluminum fiber structures of Examples 1 to 10 were confirmed by a microscope when the aluminum fiber structures were cut. It was found that an aluminum oxide layer was formed on the surface of the aluminum fiber, and a plurality of protrusions of aluminum oxide having a height greater than the thickness of the aluminum oxide layer were formed on the surface of the aluminum oxide layer or the aluminum fiber. On the other hand, the cut surfaces of the aluminum fiber structures of Comparative Examples 1 to 3 were confirmed by a microscope when the aluminum fiber structures were cut. It was found that an aluminum oxide layer was formed on the surface of the aluminum fiber, but no protrusions of aluminum oxide were formed on the surface of the aluminum oxide layer or the aluminum fiber. Further, the linear expansion coefficients of the aluminum fiber structures of Examples 1 to 10 and Comparative Examples 1 to 3 were measured. The linear expansion coefficients of the aluminum fiber structures of Examples 1 to 10 were all 22.0 or less, while the linear expansion coefficients of the aluminum fiber structures of Comparative Examples 1 to 3 were all greater than 23.0. From the above results, it was found that the linear expansion coefficient of the aluminum fiber structure can be reduced when the aluminum fiber is heated at 700°C or higher in the interior of the sintering apparatus to sinter the aluminum fiber.

[0070] Example 11

[0071] An aluminum composite shown in FIG. 11 was prepared by bonding two aluminum fiber structures with a resin. Figure 2 The aluminum composite of Example 11 is a material in which the resin is locally impregnated in the aluminum fiber structures. Specifically, by locally impregnating the resin in the two aluminum fiber structures, the aluminum fiber structures protrude outward from the surface and the back surface of the resin at the portions near the surface side and the back side of the resin in which the aluminum fiber structures are located, respectively. As the aluminum fiber structures, the aluminum fiber structures of Example 1 were used, and the thickness of each aluminum fiber structure was 3.0 mm and the packing factor was 75%. Further, as the resin of the bonding layer, an epoxy resin was used, and the thickness of the bonding layer was 125 μm.

[0072] Example 12

[0073] An aluminum composite shown in FIG. 12 was prepared by bonding two aluminum fiber structures with a bonding layer made of an adhesive of silver paste. Figure 3 As the aluminum fiber structures, the aluminum fiber structures of Example 1 were used, and the thickness of each aluminum fiber structure was 3.0 mm and the packing factor was 75%. Further, the thickness of the bonding layer made of the adhesive of silver paste was 12 μm.

[0074] Example 13

[0075] An aluminum composite shown in FIG. 13 was prepared by bonding a copper plate to one surface of an aluminum fiber structure with a bonding layer made of an adhesive of copper paste. Figure 4An aluminum composite material shown in Table 1 was prepared. As the aluminum fiber structure, the aluminum fiber structure of Example 3 was used, and the thickness of each aluminum fiber structure was 1.0 mm and the packing factor was 72%. In addition, the thickness of the adhesive layer made of the adhesive of the copper paste was 48 μm. In addition, as the copper plate, a material having a material quality of C1100, a thickness of 5.0 mm, and a packing factor of 100% was used.

[0076] Example 14

[0077] An aluminum composite material shown in Table 1 was prepared. As the aluminum fiber structure, the aluminum fiber structure of Example 3 was used, and the thickness of each aluminum fiber structure was 1.0 mm and the packing factor was 72%. In addition, the thickness of the adhesive layer made of the adhesive of the copper paste was 48 μm. In addition, as the copper plate, a material having a material quality of C1100, a thickness of 5.0 mm, and a packing factor of 100% was used. Figure 5

[0078] Comparative Example 4

[0079] An aluminum composite material shown in Table 1 was prepared. As the aluminum fiber structure, the aluminum fiber structure of Example 3 was used, and the thickness of each aluminum fiber structure was 1.0 mm and the packing factor was 72%. In addition, the thickness of the adhesive layer made of the adhesive of the copper paste was 48 μm. In addition, as the copper plate, a material having a material quality of C1100, a thickness of 5.0 mm, and a packing factor of 100% was used. Figure 5

[0080] Comparative Example 5

[0081] An aluminum composite material shown in Table 1 was prepared. As the aluminum fiber structure, the aluminum fiber structure of Example 3 was used, and the thickness of each aluminum fiber structure was 1.0 mm and the packing factor was 72%. In addition, the thickness of the adhesive layer made of the adhesive of the copper paste was 48 μm. In addition, as the copper plate, a material having a material quality of C1100, a thickness of 5.0 mm, and a packing factor of 100% was used.

[0082] ​​<Evaluation>

[0083] The adhesion and the adhesive strength of the aluminum composite material and the alumina composite material of Examples 11 to 14 and Comparative Examples 4 to 5 were evaluated. In terms of the adhesion, the thermal shock test (500 cycles between -40°C and 120°C, the total holding time was 30 minutes) was performed on the aluminum composite material and the alumina composite material of Examples 11 to 14 and Comparative Examples 4 to 5, and the occurrence of peeling was visually observed. In the case where no peeling occurred, it was evaluated as "O", and in the case where partial peeling or the occurrence of lifting of the composite member occurred, it was evaluated as "X". In addition, in terms of the adhesive strength, the rate of change in the adhesive strength before and after the thermal shock test was calculated for the aluminum composite material and the alumina composite material of Examples 11 to 14 and Comparative Examples 4 to 5. The measurement of the adhesive strength was performed according to JIS K 6854-2: 1999 (ISO 8510-2: 1990) to measure the tensile strength. In the case where the rate of change in the adhesive strength before and after the thermal shock test was less than 10%, it was evaluated as "◎", in the case where it was less than 30%, it was evaluated as "O", and in the case where it was 30% or more, it was evaluated as "X". The evaluation results are shown in Table 3 below.

[0084] [Table 3]

[0085]

[0086] As shown in the evaluation results of Table 3, in the case where the aluminum fiber structure was used as the aluminum composite material, the adhesion and the adhesive strength were good. Specifically, peeling was difficult to occur, and in addition, even if the temperature of the surrounding environment changed, the adhesive strength was not easily changed. On the other hand, in the case where the aluminum plate and the alumina plate were used as the aluminum composite material instead of the aluminum fiber structure, the adhesion and the adhesive strength were deteriorated compared to the case where the aluminum fiber structure was used. In this way, in the case where the aluminum fiber structure was used as the aluminum composite material, even in the case where the temperature of the surrounding environment greatly changed, peeling was not easily occurred between the aluminum fiber structure and the composite material.

Claims

1. An aluminum fiber structure, characterized by comprising: aluminum fibers, the aluminum fibers being locally bonded to each other, an aluminum oxide layer being formed on surfaces of the aluminum fibers, a plurality of protrusions of aluminum oxide being formed on a surface of the aluminum fibers or the aluminum oxide layer, the protrusions having a height greater than a thickness of the aluminum oxide layer, a plasma-resistant layer being formed on a surface of the aluminum oxide layer and the protrusions.

2. The aluminum fiber structure according to claim 1, characterized in that at least a portion of the protrusions of the plurality of protrusions straddle the aluminum oxide layer of the plurality of aluminum fibers and are in contact with the aluminum oxide layer.

3. The aluminum fiber structure according to claim 1 or 2, characterized in that the height of the protrusions with respect to the surface of the aluminum fibers or the aluminum oxide layer is in a range of 10 nm to 10 μm.

4. The aluminum fiber structure according to any one of claims 1 to 3, characterized in that the thickness of the aluminum oxide layer is in a range of 10 nm to 10 μm.

5. The aluminum fiber structure according to any one of claims 1 to 3, characterized in that the protrusions cover 20% or more of the surface of the aluminum fibers in a cross section of the aluminum fiber structure.

6. The aluminum fiber structure according to any one of claims 1 to 5, characterized in that the protrusions collectively cover 40% or more of the surface of the aluminum fibers in a cross section of the aluminum fiber structure.

7. The aluminum fiber structure according to claim 1, characterized in that the plasma-resistant layer contains a metal oxide or aluminum nitride.

8. The aluminum fiber structure according to any one of claims 1 to 7, characterized in that the protrusions are formed of a substance that is exuded from the aluminum fibers by sintering the aluminum fibers at 700°C or higher.

9. The aluminum fiber structure according to any one of claims 1 to 8, characterized in that a packing factor of the aluminum fibers in the aluminum fiber structure is in a range of 20% to 90%.

10. An aluminum composite material, characterized by comprising: the aluminum fiber structure according to any one of claims 1 to 9 and a composite material, the protrusions of the aluminum oxide being in contact with at least a portion of the composite material. ​ ​ ​ ​ ​ ​ ​ ​ ​

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