METHOD FOR MANUFACTURING Al-AlN COMPOSITE MATERIAL

Abstract

To provide a method for manufacturing an Al-AlN composite material, capable of forming a metal layer and a gradient layer on both sides of a ceramic base material in a simple process.SOLUTION: A method for manufacturing an Al-AlN composite material comprises: arranging an Al-Mg alloy material 20 on the upper surface of a ceramic base material 10 and arranging a lower side Al material 21 through a nitriding accelerator 22 on the lower surface; melting the Al-Mg alloy material and the lower side Al material and supplying N2 gas; reacting the Mg of the Al-Mg alloy material to N2 gas to form Mg3 N2 and precipitating it into the Al-Mg alloy material to form AlN; forming a first AlN layer 11a, a first Al-AlN layer 11b, and a first Al layer 11c in this order on the upper surface of the ceramic base material; precipitating the nitriding accelerator into the molten lower side Al material and promoting the Al nitriding of the lower side Al material by the nitriding accelerator to form AlN; and forming a second AlN layer 12a, a second Al-AlN layer 12b, and a second Al layer 12c in this order on the lower surface of the ceramic base material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for producing an Al-AlN composite material. [Background technology]

[0002] For example, when a power device for power control is cooled by a heat exchanger, an insulating plate is provided between the electrode plate of the power device and the heat exchanger. If air is present on the contact surface between the insulating plate and the power device and the heat exchanger, thermal resistance increases, so grease is provided between the insulating plate and the power device and the heat exchanger. However, when grease is provided on both sides of the insulating plate, thermal resistance due to the grease occurs in two places, so it is not possible to sufficiently suppress the increase in thermal resistance from the power module to the heat exchanger.

[0003] In response to this, for example, Patent Document 1 proposes a composite material in which a metal layer and a ceramic layer are integrated via a gradient layer. By providing such a composite material between the power device and the heat exchanger, it is only necessary to provide grease on one side of the insulating plate, and it is possible to suppress an increase in thermal resistance from the power device to the heat exchanger while ensuring insulation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-140904 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the composite material of Patent Document 1, the bonding strength between the metal layer and the ceramic layer is low, so there is a risk of peeling at the bonding interface.

[0006] It is also possible to form a composite material on both sides of the substrate to eliminate the need for a grease layer, but in this case, it is necessary to perform a step of forming a composite material on one side of the substrate and then a step of forming a composite material on the other side of the substrate, which complicates the process.

[0007] In view of the above, the present invention aims to provide a method for manufacturing an Al-AlN composite material that can improve the bonding strength between the aluminum and aluminum nitride of a composite material and that can form a composite material on both sides of a substrate in a simple process. [Means for solving the problem]

[0008] In order to achieve the above object, in the invention described in claim 1, an Al-Mg alloy material (20) is arranged on an upper surface of a ceramic base material (10), and a lower Al material (21) is arranged on a lower surface of the ceramic base material with a nitriding promoter (22) interposed therebetween.

[0009] The Al-Mg alloy material and the lower Al material are heated to a predetermined temperature to melt them, and N2 gas is supplied to the Al-Mg alloy material and the lower Al material. The Mg in the Al-Mg alloy material reacts with the N2 gas to generate Mg3N2, which is precipitated inside the molten Al-Mg alloy material, and the Al in the molten Al-Mg alloy material reacts with the Mg3N2 to generate AlN.

[0010] A first AlN layer (11a) in which AlN is formed so as to cover the upper surface of the ceramic substrate, a first Al-AlN layer (11b) containing Al and AlN of an Al-Mg alloy material, and a first Al layer (11c) in which Al of the Al-Mg alloy material is exposed on the surface are formed in that order on the upper surface of the ceramic substrate. The lower Al material, in which the nitriding promoter has been melted, is nitrided with N2 gas to promote the nitridation of Al, producing AlN.

[0011] A second AlN layer (12a) in which AlN is formed so as to cover the ceramic substrate, a second Al-AlN layer (12b) containing Al and AlN of the lower Al material, and a second Al layer (12c) in which the Al of the lower Al material is exposed on the surface are formed in that order on the lower surface of the ceramic substrate.

[0012] This makes it possible to form a composite material having an AlN layer, an Al-AlN layer, and an Al layer simultaneously on both sides of a ceramic substrate using a simple process.

[0013] The reference characters in parentheses for each of the above components indicate the corresponding relationship with the specific means described in the embodiments described later. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a state in which an Al—AlN composite material of a first embodiment is used. [Diagram 2] FIG. 1 is a cross-sectional view showing the configuration of an Al-AlN composite material. [Diagram 3] FIG. 1 is a diagram showing a manufacturing apparatus for an Al—AlN composite material according to a first embodiment. [Figure 4] 3A to 3C are diagrams illustrating a state in which raw materials are placed on the upper and lower surfaces of a ceramic substrate in a manufacturing process according to the first embodiment. [Diagram 5] FIG. 1 is a diagram showing the N2 gas supply amount and heating temperature in the manufacturing process of an Al-AlN composite material. [Figure 6] FIG. 2 is a diagram showing the molten state of an Al-Mg alloy material, etc. [Figure 7] FIG. 1 is a diagram showing a state in which Mg3N2 precipitates in an Al-Mg alloy material and a peeling material precipitates in an Al material. [Figure 8] FIG. 2 is a diagram showing a state in which an AlN layer is formed on a ceramic substrate. [Figure 9] FIG. 2 is a diagram showing a state in which an Al—AlN layer and an Al layer are formed on an AlN layer. [Figure 10] FIG. 1 shows the results of X-ray diffraction measurement of an Al-AlN composite material. [Figure 11] 1 is a SEM image showing the Al layer of an Al-AlN composite material. [Figure 12] This is a longitudinal cross-sectional image of an Al-AlN composite material. [Figure 13] FIG. 11 is a diagram showing a manufacturing apparatus for an Al—AlN composite material according to a second embodiment. [Figure 14] 13A and 13B are diagrams illustrating a state in which raw materials are placed on the upper and lower surfaces of a ceramic substrate in a manufacturing process according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a number of embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, the same reference numerals may be used to designate parts corresponding to matters described in the preceding embodiment, and duplicated descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other embodiments described previously may be applied to other parts of the configuration. In addition to combinations of parts that are specifically indicated as being possible in each embodiment, it is also possible to partially combine embodiments even if not indicated, as long as there is no particular problem with the combination.

[0016] (First embodiment) A first embodiment of the present invention will now be described with reference to the drawings.

[0017] 1, in the first embodiment, an Al-AlN composite material 4 is used as an insulating plate disposed between a power device 1 and a heat exchanger 5. The Al-AlN composite material 4 provides insulation between the power device 1 and the heat exchanger 5 and conducts heat between the power device 1 and the heat exchanger 5. The power device 1 is a heat generating body and is cooled by the heat exchanger 5.

[0018] A heat sink 3 is joined to the power device 1 by solder 2. An Al-AlN composite material 4 is provided between the heat sink 3 and a heat exchanger 5. The heat sink 3 and the heat exchanger 5 are made of, for example, an Al material.

[0019] The Al-AlN composite material 4 has the Al material exposed on both surfaces. That is, the Al material is exposed on the surfaces of the Al-AlN composite material 4 that face the heat sink 3 and the heat exchanger 5. The heat sink 3 and the Al-AlN composite material 4, and the Al-AlN composite material 4 and the heat exchanger 5 are respectively joined by brazing. For this reason, no grease layer is provided between the heat sink 3 and the Al-AlN composite material 4, and between the Al-AlN composite material 4 and the heat exchanger 5 to reduce the thermal resistance of the contact surfaces.

[0020] 2, the Al-AlN composite material 4 includes a ceramic substrate 10, a first composite material 11, and a second composite material 12. The ceramic substrate 10 is firmly bonded to the two composite materials 11 and 12, respectively.

[0021] The two composite materials 11, 12 are provided on both sides of the ceramic substrate 10, and the ceramic substrate 10 is sandwiched between the two composite materials 11, 12. In the example shown in Fig. 2, a first composite material 11 is provided on the upper surface of the ceramic substrate 10, and a second composite material 12 is provided on the upper surface of the ceramic substrate 10.

[0022] The ceramic substrate 10 is an insulating material used as a base for forming the composite materials 11 and 12. In the first embodiment, a plate-shaped ceramic substrate 10 is used.

[0023] The ceramic substrate 10 has a melting point higher than those of Al and Mg. Furthermore, since the ceramic substrate 10 is used at temperatures equal to or higher than the boiling point of Mg, the ceramic substrate 10 is made of a material that is stable at high temperatures equal to or higher than the boiling point of Mg.

[0024] The ceramic substrate 10 is made of a material that does not chemically react with Al and Mg. Furthermore, the ceramic substrate 10 is a non-oxide material that does not thermally decompose in an inert atmosphere and does not decompose due to the reducing action of Mg3N2.

[0025] The ceramic base 10 has a hexagonal crystal structure, which allows hexagonal AlN to grow continuously from the crystals of the ceramic base 10.

[0026] As the hexagonal ceramic substrate 10, for example, any of AlN, BN, GaN, and SiC can be suitably used. These ceramics are materials with lattice constants close to those of AlN, and have lattice constants within a predetermined range based on the lattice constant of AlN (for example, within ±7% of the lattice constant of AlN). Therefore, the AlN of the composite materials 11 and 12 can be favorably grown from the ceramic substrate 10. As a result, the bonding strength between the ceramic substrate 10 and the AlN of the composite materials 11 and 12 is increased, and the composite materials 11 and 12 are less likely to peel off from the ceramic substrate 10. In the first embodiment, an AlN substrate is used as the ceramic substrate 10.

[0027] The first composite material 11 and the second composite material 12 have the same configuration. The composite materials 11 and 12 have AlN layers 11a and 12a, Al-AlN layers 11b and 12b, and Al layers 11c and 12c, in that order from the side closer to the ceramic substrate 10. The AlN layers 11a and 12a, the Al-AlN layers 11b and 12b, and the Al layers 11c and 12c are formed from a single raw material (e.g., Al material or Al-Mg alloy material). The AlN layers 11a and 12a, the Al-AlN layers 11b and 12b, and the Al layers 11c and 12c have different Al and AlN contents.

[0028] The AlN layers 11a and 12a are provided so as to contact the ceramic base material 10. The AlN layers 11a and 12a are made of AlN covering the surface of the ceramic base material 10. The AlN layers 11a and 12a are dense layers in which AlN is densely formed, and constitute insulating layers. The AlN layers 11a and 12a are preferably made of only AlN, but may contain a material other than AlN (e.g., Al). In at least the first AlN layer 11a, the AlN crystals are formed continuously from the crystals of the ceramic base material 10, and the AlN crystals are formed oriented in the C-axis direction of the hexagonal crystal system.

[0029] The Al-AlN layers 11b and 12b contain Al and AlN. In the Al-AlN layers 11b and 12b, AlN crystals are formed continuously from the AlN layers 11a and 12a. The Al-AlN layers 11b and 12b are Al-AlN gradient layers in which the content ratio of Al and AlN changes, and the content of AlN decreases and the content of Al increases as the layer gets farther from the AlN layers 11a and 12a.

[0030] At least the first Al-AlN layer 11b is configured as comb-tooth AlN 11d, in which AlN is formed in a comb-tooth shape so as to protrude from the first AlN layer 11a. The comb-tooth AlN 11d is in a state in which a plurality of columnar AlN extending from the first AlN layer 11a toward the first Al layer 11c are formed in parallel. Al is present in the gaps between adjacent comb-tooth AlN 11d, and in the first Al-AlN layer 11b, Al and Al are intertwined.

[0031] The Al layers 11c, 12c are provided on the outermost layers of the Al-AlN composite material 4, and have exposed surfaces. The Al layers 11c, 12c are mainly composed of Al, and the heat sink 3 and the heat exchanger 5 are brazed to the surfaces of the Al layers 11c, 12c. For this reason, it is desirable for the Al layers 11c, 12c to have a thickness of about several tens of μm to 100 μm.

[0032] The Al layers 11c, 12c are desirably composed only of Al, but may contain a material other than Al (e.g., AlN) to the extent that it does not interfere with brazing to the heat sink 3 or the heat exchanger 5. For example, the AlN of the Al-AlN layers 11b, 12b may be formed continuously up to the Al layers 11c, 12c and reach the surfaces of the Al layers 11c, 12c.

[0033] Next, a description will be given of the heating furnace 100 which is a manufacturing device for the Al-AlN composite material 4. The heating furnace 100 can generate AlN by creating an inert atmosphere inside the furnace.

[0034] As shown in Fig. 3, the heating furnace 100 is provided with two cylindrical members 101 and 102. The two cylindrical members 101 and 102 have a double-tube structure. The first cylindrical member 101 constitutes an outer wall, and the second cylindrical member 102 is disposed inside the first cylindrical member 101. In Fig. 3, the direction from left to right is the gas flow direction. The insides of the first cylindrical member 101 and the second cylindrical member 102 are filled with an inert atmosphere.

[0035] An N2 gas inlet 103 is provided at the most upstream portion of the first cylindrical member 101. N2 gas is introduced into the first cylindrical member 101 from an N2 gas supply device (not shown) through the N2 gas inlet 103. The N2 gas supply device is capable of adjusting the supply amount of N2 gas. The N2 gas supplied from the N2 gas supply device flows inside the first cylindrical member 101.

[0036] An inert gas inlet 104 is provided at the most upstream portion of the second cylindrical member 102. Ar gas is introduced into the second cylindrical member 102 from an inert gas supply device (not shown) through the inert gas inlet 104. The Ar gas is used as a carrier gas. The inert gas supply device is capable of adjusting the supply amount of Ar gas. The Ar gas supplied from the inert gas supply device flows inside the second cylindrical member 102.

[0037] The heating furnace 100 is provided with two tubular furnaces 105 and 106. These tubular furnaces 105 and 106 are provided so as to cover the outer periphery of the first cylindrical member 101. The first tubular furnace 105 and the second tubular furnace 106 are disposed adjacent to each other, with the first tubular furnace 105 provided on the upstream side of the gas flow and the second tubular furnace 106 provided on the downstream side of the gas flow. The two tubular furnaces 105 and 106 can be controlled in temperature individually.

[0038] The second cylindrical member 102 is shorter than the first cylindrical member 101. The downstream end of the gas flow of the second cylindrical member 102 is located near the downstream end of the gas flow of the first tubular furnace 105. Therefore, the first tubular furnace 105 can heat the insides of the first cylindrical member 101 and the second cylindrical member 102, and the second tubular furnace 106 can heat the inside of the first cylindrical member 101.

[0039] An Al-AlN forming section 108 is provided inside a portion of the first cylindrical member 101 that corresponds to the second tubular furnace 106. The Al-AlN forming section 108 can be heated by the second tubular furnace 106, and the atmospheric temperature of the Al-AlN forming section 108 can be controlled.

[0040] The Al-AlN forming section 108 is disposed downstream in the gas flow from the downstream end of the second cylindrical member 102. Raw materials for the Al-AlN composite material 4 are disposed in the Al-AlN forming section 108, and the Al-AlN composite material 4 is formed. N2 gas is supplied to the Al-AlN forming section 108. N2 gas is a gas required for forming the Al-AlN composite material 4, and is used for nitriding Al.

[0041] An upstream shielding plate 109 is provided inside the first cylindrical member 101 upstream of the gas flow downstream end of the second cylindrical member 102, and a downstream shielding plate 110 is provided downstream of the gas flow of the Al-AlN forming portion 108. The upstream shielding plate 109 and the downstream shielding plate 110 are provided to restrict the gas flow inside the first cylindrical member 101. This makes it easier for the N2 gas to remain in the Al-AlN forming portion 108, and promotes the formation of the Al-AlN composite material 4.

[0042] A gas outlet portion 111 is provided at the most downstream portion of the first cylindrical member 101. Gases such as N2 gas and Ar gas are discharged from the inside of the first cylindrical member 101 through the gas outlet portion 111.

[0043] Next, a method for manufacturing the Al-AlN composite material 4 of the first embodiment will be described. The manufacturing method of the Al-AlN composite material 4 is carried out using a heating furnace 100, and each step of a preparation step and the first to fifth steps is performed in order. 〔Preparation Step〕 In the preparation step, raw materials of the Al-AlN composite material 4 are arranged in the Al-AlN forming part 108 of the heating furnace 100. As shown in FIG. 4, the raw materials of the Al-AlN composite material 4 include a ceramic base material 10, an Al-Mg alloy material 20, and an Al material 21. The Al-Mg alloy material 20 is a raw material of the first composite material 11, and the Al material 21 is a raw material of the second composite material 12. The ceramic base material 10, the Al-Mg alloy material 20, and the Al material 21 are each plate-shaped members. The Al-Mg alloy material 20 is an upper Al-Mg alloy material arranged on the upper surface of the ceramic base material 10. The Al material 21 is a lower Al material arranged on the lower surface of the ceramic base material 10 via a nitridation accelerator 22. In the Al-Mg alloy material 20 and the Al material 21, AlN is generated in the first to fifth steps described later.

[0044] The Al-Mg alloy material 20 is directly arranged on the upper surface of the ceramic base material 10. The Al-Mg alloy material 20 is composed of a eutectic alloy of Al and Mg and has a melting point lower than that of Al. The melting point of Al is 660°C, whereas the melting point of the Al-Mg alloy material 20 used in the first embodiment is 450 to 658°C. The melting point of the Al-Mg alloy material 20 varies depending on the content ratio of Al and Mg, and the higher the Mg content, the lower the melting point.

[0045] In the Al-Mg alloy material 20 of the first embodiment, the content ratio of Al and Mg is 90 mol% ≤ content ratio of Al < 100 mol%, 0 mol% < content ratio of Mg ≤ 10 mol%. Mg contained in the Al-Mg alloy material 20 is used for the production of Mg3N2. In order to increase the production amount of Mg3N2, it is desirable to increase the Mg content in the Al-Mg alloy material 20, but from the perspective of the practical formability of the Al-Mg alloy material 20, it is desirable to set the upper limit of the Mg content to 10 mol%.

[0046] The Al material 21 is disposed on the lower surface of the ceramic base 10 via the nitriding promoter 22. That is, the nitriding promoter 22 is disposed on the upper surface of the Al material 21. A pedestal 23 is disposed on the lower surface of the Al material 21.

[0047] The nitriding accelerator 22 is a material having a higher specific gravity than the molten Al material 21. Furthermore, the nitriding accelerator 22 is a material having a melting point sufficiently higher than Al and does not easily react with Al. Therefore, the nitriding accelerator 22 disposed on the upper surface of the Al material 21 sinks in the molten Al material 21.

[0048] The nitriding promoter 22 has a function of promoting the nitridation of Al constituting the Al material 21 and promoting the generation of AlN. In other words, the nitriding promoter 22 contributes to the AlN generation reaction in the Al material 21. When the nitriding promoter 22 settles in the Al material 21, N2 is once adsorbed onto the particles diffusing to the Al surface, and some of the N2 bonds are used to bond with the solid, which makes it easier for the N2 molecules to dissociate, and it is considered that this promotes the nitridation of Al.

[0049] The nitriding promoter 22 is a material that has low surface free energy, poor wettability with respect to the molten Al material 21, and a large contact angle with the Al material 21, and has a function of facilitating peeling of the second composite material 12 generated from the Al material 21 from the pedestal 23. In other words, the nitriding promoter 22 also functions as a peeling agent.

[0050] In order for the nitriding accelerator 22 to function as a stripping agent, it is necessary that the components of the nitriding accelerator 22 diffuse from inside the molten Al material 21 to the surface of the Al material 21 and do not form a strong bond with Al when the Al is solidified by cooling. The nitriding accelerator 22 diffuses from inside the molten Al to the Al surface and coagulates, thereby weakening the bond between the solidified Al and the pedestal 23 with which the Al is in contact. It is desirable for the nitriding accelerator 22 to be a material whose melting point is sufficiently higher than the melting point of Al and which does not easily react with Al.

[0051] A commercially available mold release agent can be used as the nitriding accelerator 22. For example, ABN-903 (a mixed material of Al2O3 and BN) available from Shinagawa Fine Ceramics Co., Ltd., SUPER-COAT (a mixed material of ZrO2 and SiO2) available from Nippon Crucible Co., Ltd., and ZTA (a mixed material of ZrO2 and Al2O3) available from Maruwa Corporation can be used as the nitriding accelerator 22.

[0052] In the present first embodiment, a mixed material of Al2O3 and BN is used as the nitriding accelerator 22. The BN contained in the nitriding accelerator 22 has the same hexagonal crystal structure as the ceramic base material 10. The relationship between the specific gravity of Al2O3 and BN contained in the nitriding accelerator 22 of the present first embodiment and that of molten Al is Al2O3>BN>Al.

[0053] The pedestal 23 is used for placing the ceramic substrate 10, the Al-Mg alloy material 20, and the Al material 21 in the manufacturing process of the Al-AlN composite material 4. The pedestal 23 is a heat-resistant material, and a metal or ceramic having a high melting point can be used.

[0054] The base 23 needs to be chemically and mechanically stable in the heating temperature range of the manufacturing process. In the manufacturing process of this embodiment, the maximum heating temperature of the Al-Mg alloy material 20 and the Al material 21 is the fourth temperature T4 of 1160°C. For this reason, a material that has a melting point higher than 1160°C and is chemically and mechanically stable against heating at 1160°C is used as the base 23. In this first embodiment, ZrO2 is used as the base 23.

[0055] Following the above preparation steps, steps 1 to 5 are performed. As shown in Fig. 5, in steps 1 to 5, temperature control by the heating furnace 100 and N2 gas supply amount control are performed. The heating temperature and N2 gas supply amount by the heating furnace 100 are controlled in multiple stages. Through steps 1 to 5, a first composite material 11 is formed from the Al-Mg alloy material 20, and a second composite material 12 is formed from the Al material 21, and the two composite materials 11, 12 are simultaneously produced on both sides of the ceramic substrate 10. [1st process] In the first step, after the raw materials of the Al-AlN composite material 4 are placed in the Al-AlN forming portion 108, the supply of N2 gas is started in the first cylindrical member 101, and the supply of Ar gas is started in the second cylindrical member 102. As a result, N2 gas is supplied to the Al-AlN forming portion 108, and N2 gas is simultaneously supplied to the Al-Mg alloy material 20 and the Al material 21. The supply amount of N2 gas is increased until it reaches a predetermined value, and after it reaches the predetermined value, the supply amount of N2 gas is maintained.

[0056] 5, in the first step, the heating temperature of the Al-AlN forming portion 108 by the second tubular furnace 106 is set to a first temperature T1. As a result, the Al-Mg alloy material 20 and the Al material 21 arranged above and below the ceramic base material 10 are simultaneously heated to the first temperature T1.

[0057] The first temperature T1 is a temperature equal to or higher than the melting points of the Al-Mg alloy and Al. The first temperature T1 is also a temperature lower than the lower limit temperature for forming AlN. The lower limit temperature for forming AlN is the lower limit temperature at which AlN can be formed by the reaction of Mg3N2 and Al, and is the temperature at which the AlN forming reaction starts. The lower limit temperature for forming AlN can be, for example, 780°C. In the first embodiment, the first temperature T1 is set to, for example, 660°C.

[0058] The heating of the Al-Mg alloy material 20 and the Al material at the first temperature T1 is performed for a first predetermined time period, which is set to 3.5 hours in the present first embodiment.

[0059] By heating the Al-Mg alloy material 20 and the Al material 21 at the first temperature T1, the Al-Mg alloy material 20 and the Al material 21 melt.

[0060] As shown in Fig. 6, in the molten Al-Mg alloy material 20, Mg rises toward the surface due to the difference in specific gravity with Al. As shown in Fig. 7, Mg that reaches the surface of the Al-Mg alloy material 20 reacts with N2 gas present in the vicinity of the surface of the Al-Mg alloy material 20 to generate Mg3N2. Since Mg3N2 has a larger specific gravity than the molten Al-Mg alloy material 20, Mg3N2 settles inside the molten Al-Mg alloy material 20 due to the difference in specific gravity.

[0061] In the first step, the first temperature is lower than the lower limit temperature for the formation of AlN. Therefore, Mg3N2 reaches the ceramic substrate 10 without reacting with Al during the process of settling inside the molten Al-Mg alloy material 20, and is deposited on the ceramic substrate 10. While the Al-Mg alloy material 20 is heated at the first temperature T1, Mg3N2 is deposited on the ceramic substrate 10. By depositing Mg3N2 on the ceramic substrate 10, Mg3N2 is dissolved in the ceramic substrate 10, and the strength of the ceramic substrate 10 is improved.

[0062] In the first step, by using the Al-Mg alloy material 20 having a melting point lower than that of Al, Mg3N2 can be deposited on the ceramic substrate 10 at a lower temperature than when an Al material is used. Furthermore, by using the Al-Mg alloy material 20 in the first step, Mg3N2 can be generated using Mg contained in the Al-Mg alloy material 20.

[0063] 6, in the molten Al material 21, Al2O3 and BN constituting the nitriding accelerator 22 settle in the Al material 21 due to the difference in specific gravity with Al. Since the specific gravities of these materials are in the order of Al2O3>BN>Al, Al2O3 settles preferentially in the Al material 21 and accumulates on the upper surface of the pedestal 23.

[0064] The first step is also an Mg3N2 deposition step in which Mg3N2 is deposited on the ceramic substrate 10. [Second process] 5, in the second step, the heating temperature of the Al-AlN forming portion 108 by the second tubular furnace 106 is set to a second temperature T2. It takes 0.5 hours for the heating temperature by the second tubular furnace 106 to increase from the first temperature T1 to the second temperature T2.

[0065] By changing the heating temperature by the second tubular furnace 106, the Al-Mg alloy material 20 and the Al material 21 are heated at a second temperature T2. The second temperature T2 is a temperature higher than the first temperature T1 and is set within a predetermined temperature range having the AlN formation lower limit temperature as a lower limit value. In the predetermined temperature range, for example, the AlN formation lower limit temperature can be set as the lower limit value and about the AlN formation lower limit temperature + 30°C can be set as the upper limit value. In the first embodiment, the second temperature T2 is set to 780°C.

[0066] In the second step, the heating of the Al-Mg alloy material 20 at the second temperature T2 is performed for a second predetermined time. The second predetermined time is the time required for the Mg3N2 deposited on the ceramic substrate 10 to react with Al in the Al-Mg alloy material 20 to generate AlN and form the first AlN layer 11a on the upper surface of the ceramic substrate 10. The second predetermined time is also the time required for the AlN to be generated inside the Al material 21 and for the second AlN layer 12a to be formed on the lower surface of the ceramic substrate 10. In the first embodiment, the second predetermined time is set to 6 hours.

[0067] In the second step, the supply amount of N2 gas is not changed from that in the first step. Therefore, in the second step, the amount of Mg3N2 generated in the Al-Mg alloy material 20 does not change from that in the first step, and Mg3N2 settles inside the molten Al-Mg alloy material 20 in the same manner as in the first step.

[0068] In the second step, Al of the Al-Mg alloy material 20 reacts with Mg3N2 deposited on the ceramic substrate 10 to form AlN by the following AlN formation reaction.

[0069] 2Al+Mg3N2→AlN+3Mg As a result, AlN grows epitaxially on the ceramic base material 10, and AlN seed crystals are formed. The AlN seed crystals are formed at any positions on the ceramic base material 10. Mg produced by decomposition of Mg3N2 in the AlN production reaction diffuses into the molten Al-Mg alloy material 20.

[0070] In the second step, by continuing to heat the Al-Mg alloy material 20 at the second temperature T2, AlN crystals grow from the AlN seed crystals formed on the ceramic base material 10 so as to spread over the two-dimensional plane of the ceramic base material 10, and the AlN further grows in an oriented manner in the C-axis direction of the hexagonal crystal from the ceramic base material 10.

[0071] In the Al material 21, the nitriding promoter 22 settles inside the molten Al material 21 in the same manner as in the first step. The nitriding promoter 22 promotes the nitridation of Al and promotes the generation of AlN. Therefore, in the second step, by continuing to heat the Al material 21 at the second temperature T2, AlN crystals are formed on the lower surface of the ceramic base material 10.

[0072] 8, in the second step, a first AlN layer 11a is formed to cover the upper surface of the ceramic base material 10, and a second AlN layer 12a is formed to cover the lower surface of the ceramic base material 10. The first AlN layer 11a and the second AlN layer 12a form dense layers in which the surface of the ceramic base material 10 is covered with AlN.

[0073] In the first embodiment, prior to the second step of producing AlN, Mg3N2 is deposited on the ceramic base material 10 in the first step. Therefore, in the second step, AlN can be produced by reacting Mg3N2 with Al on the upper surface of the ceramic base material 10, and the first AlN layer 11a having a predetermined thickness can be efficiently formed on the upper surface of the ceramic base material 10.

[0074] In the second step, AlN is generated at a second temperature T2 set within a predetermined temperature range including the lower limit temperature for generating AlN. In the first embodiment, the quality of the generated AlN can be improved by performing the AlN generating reaction at a temperature as low as possible, and the AlN layers 11a and 12a in which AlN is densely formed can be obtained. In addition, in the Al-Mg alloy material 20, by reacting Mg3N2 and Al at a temperature as low as possible, it is possible to prevent the generation of unreacted N2 gas and the formation of voids when Mg3N2 decomposes.

[0075] The second step is an AlN layer forming step in which a first AlN layer 11a is formed on the upper surface of the ceramic base material 10 and a second AlN layer 12a is formed on the lower surface of the ceramic base material 10. [3rd step] 5, in the third step, after the second step is completed, the heating temperature of the Al-AlN forming portion 108 by the second tubular furnace 106 is increased from the second temperature T2 to a third temperature T3 while the supply amount of N2 gas is gradually decreased. The third temperature T3 will be described later.

[0076] In the third step, the temperature is increased from the second temperature T2 to the third temperature T3 over a third predetermined time period, which is set to 8 hours in the first embodiment.

[0077] In the third step, the supply amount of N2 gas is gradually decreased. As a result, the amount of Mg3N2 produced is gradually decreased in the Al-Mg alloy material 20, and the amount of AlN produced is gradually decreased. In the Al material 21, the supply amount of N2 gas is gradually decreased, and the amount of AlN produced is also gradually decreased.

[0078] A first Al-AlN layer 11b, which is an Al-AlN gradient layer in which the content ratio of Al and AlN changes, is formed on the first AlN layer 11a. A second Al-AlN layer 12b, which is an Al-AlN gradient layer in which the content ratio of Al and AlN changes, is formed under the second AlN layer 12a.

[0079] In the third step, Al reacts with Mg3N2 that has newly precipitated inside the molten Al-Mg alloy material 20, and new AlN is formed on the first AlN layer 11a. The AlN crystal grows while being oriented in the C-axis direction of the hexagonal crystal.

[0080] In the third step, the amount of Mg3N2 produced is reduced, so that the amount of Mg3N2 that settles inside the molten Al-Mg alloy material 20 is reduced, and the amount of AlN formed on the first AlN layer 11a is reduced. Therefore, as shown in FIG. 9, AlN is partially formed on the first AlN layer 11a, and AlN is formed so as to protrude from the first AlN layer 11a. In the first composite material 11, comb-tooth AlN 11d is formed in such a way that AlN protrudes from the first AlN layer 11a. Al from the Al-Mg alloy material 20 enters the gaps between adjacent comb-tooth AlN 11d.

[0081] The third step is an Al-AlN layer forming step in which the first Al-AlN layer 11b and the second Al-AlN layer 12b are formed. [4th step] As shown in FIG. 5, in the fourth step, after completion of the temperature increase from the second temperature T2 to the third temperature T3 in the third step, the heating temperature of the Al-AlN forming portion 108 by the second tubular furnace 106 is maintained at the third temperature T3.

[0082] In the fourth step, a small amount of N2 gas is supplied. In the fourth step, the generation of Mg3N2 in the Al-Mg alloy material 20 has almost stopped.

[0083] In the fourth step, after the generation of Mg3N2 in the Al-Mg alloy material 20 stops, the Al-Mg alloy material 20 and the Al material 21 are heated at a third temperature T3. The third temperature T3 is a temperature set within a predetermined temperature range including a complete nitriding temperature. The complete nitriding temperature is the lower limit temperature at which all of the Mg3N2 present inside the molten Al-Mg alloy material 20 can be reacted with Al. The complete nitriding temperature can be set to, for example, 1000°C.

[0084] The third temperature T3 can be set to a temperature lower than the complete nitriding temperature, but is desirably set to a temperature equal to or higher than the complete nitriding temperature. In the first embodiment, the third temperature T3 is set to, for example, 1040°C.

[0085] The heating at the third temperature T3 is performed for a fourth predetermined time. The fourth predetermined time may be a time required for all of the Mg3N2 present in the molten Al-Mg alloy material 20 to react with Al and for the AlN generating reaction to be completed. In the first embodiment, the fourth predetermined time is set to 2 hours.

[0086] The supply of N2 gas in the fourth step is terminated before the fourth predetermined time has elapsed. The supply time of N2 gas in the fourth step is set to 1.5 hours.

[0087] In the fourth step, all of the Mg3N2 remaining inside the Al-Mg alloy material 20 reacts with Al, and the crystal growth of AlN is completed. In the fourth step, the crystal growth of AlN is also completed in the Al material 21. In the fourth step, the formation of the first Al-AlN layer 11b and the second Al-AlN layer 12b is completed.

[0088] The fourth step, together with the third step, is an Al-AlN layer forming step of forming a first Al-AlN layer 11b on the first AlN layer 11a and a second Al-AlN layer 12b on the second AlN layer 12a. [5th ​​process] 5, in the fifth step, after the fourth step is completed, the Al-Mg alloy material 20 and the Al material 21 are heated at a fourth temperature T4 in the second tubular furnace 106. The fourth temperature T4 is a temperature equal to or higher than the boiling point of Mg (1091°C) and lower than the boiling point of Al. In the first embodiment, the fourth temperature T4 is set to, for example, 1160°C.

[0089] The heating of the Al-Mg alloy material 20 at the fourth temperature T4 is performed for a fourth predetermined time. The fourth predetermined time may be a time required to remove Mg from the Al-Mg alloy material 20. In the first embodiment, the fourth predetermined time is set to 2 hours.

[0090] In the fifth step, Mg produced by decomposition of Mg3N2 in the AlN production reaction is evaporated and removed from the molten Al-Mg alloy material 20, thereby improving the quality of the Al-AlN composite material 4.

[0091] The fifth step is a Mg removal step in which Mg is removed from the Al—Mg alloy material 20 .

[0092] After the fifth step is completed, the heating by the tubular furnaces 105 and 106 is stopped, so that the molten Al solidifies. A first composite material 11 made of a first AlN layer 11a, a first Al-AlN layer 11b, and a first Al layer 11c is formed on the upper surface of the ceramic substrate 10. A second composite material 12 made of a second AlN layer 12a, a second Al-AlN layer 12b, and a second Al layer 12c is formed on the lower surface of the ceramic substrate 10.

[0093] After the composite materials 11 and 12 are formed on both sides of the ceramic substrate 10, the lower second composite material 12 is peeled off from the pedestal 23. At this time, Al2O3 and BN contained in the nitriding promoter 22 are deposited on the upper surface of the pedestal 23, and Al2O3 is present between the pedestal 23 and the second Al layer 12c. These materials do not form strong bonds with Al when Al solidifies, so the pedestal 23 and the second Al layer 12c are in a state where they can be easily peeled off. The nitriding promoter 22 remains on the peeled second Al layer 12c and the pedestal 23, and the Al-AlN composite material 4 is completed by scraping off the nitriding promoter 22 remaining on the second Al layer 12c.

[0094] Here, the Al-AlN composite material 4 produced by the above-mentioned production method will be described. Fig. 10 shows the results of measuring the surface of the first composite material 11 by X-ray diffraction, and Fig. 11 is an SEM image of the surface of the first composite material 11. In Fig. 10, the circles indicate the peaks of AlN, and the triangles indicate the peaks of Al.

[0095] As shown in Fig. 10, it was confirmed that Al and AlN were present on the surface of the first composite material 11. In Fig. 11, it was confirmed that hexagonal AlN and cubic Al were exposed on the surface of the first composite material 11.

[0096] Fig. 12 is a longitudinal cross-sectional image of the ceramic substrate 10 and the first composite material 11, showing the analysis results by an electron probe microanalyzer (EPMA). In Fig. 12, in the first Al-AlN layer 11b and the first Al layer 11c, the areas shown with a high concentration indicate the areas where AlN exists, and the areas shown with a low concentration indicate the areas where Al exists. As shown in Fig. 12, it was confirmed that the first AlN layer 11a, the first Al-AlN layer 11b, and the first Al layer 11c were formed in layers on the ceramic substrate 10.

[0097] The Al-AlN composite material 4 of the first embodiment described above has composite materials 11, 12 formed on both sides of a ceramic substrate 10, and the composite materials 11, 12 have Al layers 11c, 12c with Al exposed on the surface. Therefore, the Al layers 11c, 12c can be joined to the heat sink 3 or the heat exchanger 5 by brazing, and there is no need to provide a grease layer between the Al-AlN composite material 4 and the heat sink 3 or the heat exchanger 5, making it possible to significantly reduce the thermal resistance compared to a configuration in which a grease layer is provided.

[0098] In the method for producing the Al-AlN composite material 4 of the first embodiment, an Al-Mg alloy material 20 is disposed on the upper surface of the ceramic substrate 10, and an Al material 21 is disposed on the lower surface of the ceramic substrate 10 via a nitriding promoter 22. AlN is generated in the Al-Mg alloy material 20 via the generation of Mg3N2, and AlN is generated in the Al material 21 by the nitriding promoter 22 that promotes the nitriding of Al, so that the composite materials 11 and 12 can be formed on both sides of the ceramic substrate 10. In this way, according to the first embodiment, the composite materials 11 and 12 can be formed simultaneously on both sides of the ceramic substrate 10 by a simple process.

[0099] Furthermore, when the two composite materials 11, 12 are formed in order on one side and the other side of the ceramic substrate 10, warping is likely to occur in the Al-AlN composite material 4. In contrast, in the first embodiment, the two composite materials 11, 12 are simultaneously formed on both sides of the ceramic substrate 10, so that warping of the Al-AlN composite material 4 can be suppressed as much as possible.

[0100] In the first embodiment, the Al material 21 is disposed on the lower surface of the ceramic substrate 10 via the nitriding promoter 22, and the nitriding promoter 22 settles inside the molten Al material 21. Since the nitriding promoter 22 has a function of promoting the nitridation of Al, the second composite material 12 made of the second AlN layer 12a, the second Al-AlN layer 12b, and the second Al layer 12c can be formed from the Al material 21.

[0101] In the first embodiment, the Al material 21 is disposed on the lower surface of the ceramic base material 10 via the nitriding promoter 22, and the nitriding promoter 22 settles inside the molten Al material 21. Al2O3 contained in the nitriding promoter 22 is deposited on the upper surface of the pedestal 23, and Al2O3 is present between the pedestal 23 and the second Al layer 12c, so that the pedestal 23 and the second Al layer 12c can be easily peeled off.

[0102] At least the first composite material 11 has an Al-AlN layer 11b having a complex structure of Al and AlN, improving the bonding strength at the interface between Al and AlN. Therefore, even if rapid temperature changes occur repeatedly, the internal stress of the Al-AlN composite material 4 can be alleviated and the occurrence of cracks can be suppressed. Furthermore, the thermal strain inside the Al-AlN composite material 4 can be alleviated and peeling at the bonding interface between Al and AlN can be suppressed.

[0103] In the method for producing the Al-AlN composite material 4 of the first embodiment, the amount of Mg3N2 generated is controlled by adjusting the supply amount of N2 gas, and the heating temperature of the Al-Mg alloy material 20 is controlled in multiple stages. This makes it possible to obtain the first composite material 11 in which the AlN layer 11a, the Al-AlN layer 11b, and the Al layer 11c are formed in this order on the ceramic substrate 10.

[0104] In the manufacturing method of the Al-AlN composite material 4 of the first embodiment, in the first step, the Al-Mg alloy material 20 is heated at a first temperature T1 that is equal to or higher than the melting points of the Al-Mg alloy and Al and is lower than the lower limit temperature at which the AlN generating reaction occurs. This allows Mg3N2 to be deposited on the ceramic substrate 10 in the first step prior to the second step of generating AlN. Therefore, in the second step, Mg3N2 and Al can be reacted on the ceramic substrate 10 to generate AlN, and a first AlN layer 11a having a predetermined thickness can be formed on the ceramic substrate 10.

[0105] In the manufacturing method of the Al-AlN composite material 4 of the first embodiment, in the second step, AlN is generated at the second temperature T2 set within a predetermined temperature range including the lower limit temperature for AlN generation. This allows the AlN generation reaction for generating AlN to proceed at as low a temperature as possible, improves the quality of AlN, and makes it possible to obtain the first AlN layer 11a and the second AlN layer 12a in which AlN is densely formed.

[0106] In the manufacturing method of the Al-AlN composite material 4 of the first embodiment, in the third step, the amount of Mg3N2 produced is gradually reduced by decreasing the supply amount of N2 gas while increasing the temperature of the Al-Mg alloy material 20. This makes it possible to obtain the first Al-AlN layer 11b having the comb-tooth-shaped AlN 11d formed in a comb-tooth shape protruding from the first AlN layer 11a. In the Al material 21, the amount of AlN produced can be reduced by decreasing the supply amount of N2 gas, and the second Al-AlN layer 12b can be obtained.

[0107] In the manufacturing method of the Al-AlN composite material 4 of the first embodiment, the Al-Mg alloy material 20 is heated at a third temperature T3 set within a predetermined temperature range including the complete nitriding temperature in the fourth step, whereby all of the Mg3N2 present inside the molten Al-Mg alloy material 20 is reacted with Al, the AlN generating reaction is terminated, and the Al-AlN layer 11b is completed.

[0108] In the manufacturing method of the Al-AlN composite material 4 of the first embodiment, the Al-Mg alloy material 20 is heated at a fourth temperature T4 that is equal to or higher than the boiling point of Mg and lower than the boiling point of Al in the fifth step. This causes Mg contained in the molten Al-Mg alloy material 20 to evaporate and be removed from the Al-Mg alloy material 20, thereby improving the quality of the Al-AlN composite material 4.

[0109] Second embodiment Next, a second embodiment of the present invention will be described below, focusing only on the differences from the first embodiment.

[0110] The second embodiment differs from the first embodiment in that an Al material 24 is used instead of an Al-Mg alloy material 20 as the raw material for the first composite material 11, and Mg vapor is supplied to the Al-AlN forming section 108 in the heating furnace 100.

[0111] 13, in the heating furnace 100 of the second embodiment, a Mg vapor generating part 107 is provided inside the second cylindrical member 102. The Mg vapor generating part 107 is provided in a portion of the second cylindrical member 102 corresponding to the first tubular furnace 105.

[0112] Pellet-shaped Mg is placed in the Mg vapor generating section 107. By heating the inside of the second cylindrical member 102 to the melting point of Mg or higher by the first tubular furnace 105, Mg can be vaporized in the Mg vapor generating section 107 to generate Mg vapor. The heating temperature of Mg in the Mg vapor generating section 107 may be any temperature as long as it is equal to or higher than the melting point of Mg, but is preferably equal to or higher than the boiling point of Mg.

[0113] Mg vapor generated in the Mg vapor generating section 107 is supplied to the downstream side of the gas flow by the Ar gas flowing through the second cylindrical member 102. The Mg vapor flows out from the downstream end of the gas flow of the second cylindrical member 102 and merges with the N2 gas in the first cylindrical member 101. On the downstream side of the gas flow downstream end of the second cylindrical member 102 in the first cylindrical member 101, an Mg3N2 generating reaction occurs in which the Mg vapor reacts with the N2 gas in an inert atmosphere to generate Mg3N2.

[0114] 14 , in the preparation step of the second embodiment, an Al material 24 is placed on the upper surface of the ceramic substrate 10 as a raw material of the first composite material 11. In the second embodiment, the Al material 24 placed on the upper surface of the ceramic substrate 10 as a raw material of the first composite material 11 is referred to as an upper Al material 24, and the Al material 21 placed on the lower surface of the ceramic substrate 10 is referred to as a lower Al material 21.

[0115] In the first step of the second embodiment, in addition to starting the supply of N2 gas and Ar gas, the Mg vapor generating section 107 is heated by the first tubular furnace 105 to a temperature above the melting point of Mg, preferably above the boiling point. As a result, Mg vapor is supplied to the Al-AlN forming section 108 in addition to the N2 gas, Mg3N2 is generated outside the upper Al material 24, and Mg3N2 is supplied to the upper Al material 24. The Mg3N2 supplied to the upper Al material 24 sinks in the molten upper Al material 24.

[0116] In the third step of the second embodiment, the amount of Mg3N2 produced can be controlled by adjusting the supply amount of at least one of Mg vapor and N2 gas.

[0117] In the second embodiment described above, Mg vapor is supplied to the upper Al material 24 together with N gas, and Mg3N2 generated from the N2 gas and Mg vapor is supplied to the upper Al material 24. Even with this configuration, as in the first embodiment, the first composite material 11 can be formed from the upper Al material 24, and composite materials 11, 12 can be formed on both sides of the ceramic substrate 10.

[0118] (Other embodiments) The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Furthermore, the means disclosed in each of the above-described embodiments may be appropriately combined within the scope of feasibility.

[0119] For example, in each of the above embodiments, the Al material 21 that does not contain Mg is used as the raw material of the second composite material 12, but the Al material 21 may contain Mg. In other words, the raw material of the second composite material 12 may be an Al-Mg alloy material.

[0120] In addition, in the above second embodiment, the Al material 24 is used as the raw material of the first composite material 11, and Mg vapor is supplied. However, an Al-Mg alloy material may be used as the raw material of the first composite material 11, and Mg vapor may be supplied. [Explanation of symbols]

[0121] 4 Al-AlN composite 10 Ceramic substrate 11 First composite material 12 Second composite material 20 Al-Mg alloy material 21 Al material (lower Al material) 22 Nitriding agent (stripping agent) 23 Pedestal 24 Al material (upper Al material)

Claims

1. An Al-Mg alloy material (20) is placed on an upper surface of a ceramic substrate (10), and a lower Al material (21) is placed on a lower surface of the ceramic substrate via a nitriding promoter (22); The Al-Mg alloy material and the lower Al material are heated to a predetermined temperature to melt them, and N is added to the Al-Mg alloy material and the lower Al material. ２ Supply gas, Mg and N in the Al-Mg alloy material ２ React with gas to produce Mg ３ N ２ and producing said Mg ３ N ２ is precipitated into the inside of the molten Al-Mg alloy material, and the Al and the Mg of the molten Al-Mg alloy material are mixed. ３ N ２ and reacting with each other to produce AlN, On an upper surface of the ceramic substrate, a first AlN layer (11a) in which AlN is formed so as to cover the upper surface of the ceramic substrate, a first Al-AlN layer (11b) containing Al and AlN of the Al-Mg alloy material, and a first Al layer (11c) in which Al of the Al-Mg alloy material is exposed on a surface are formed in that order; The nitriding promoter is precipitated inside the molten lower Al material, and the nitriding promoter promotes nitridation of Al in the lower Al material to generate AlN; A second AlN layer (12a) in which AlN is formed so as to cover the ceramic substrate, a second Al-AlN layer (12b) containing Al of the lower Al material and AlN, and a second Al layer (12c) in which Al of the lower Al material is exposed on the surface are formed in that order on the lower surface of the ceramic substrate. A method for producing an Al-AlN composite material.

2. An upper Al material (24) is provided on an upper surface of a ceramic substrate (10), and a lower Al material (21) is provided on a lower surface of the ceramic substrate via a nitriding promoter (22); The upper Al material and the lower Al material are heated to a predetermined temperature to melt them, and Mg vapor and N ２ Gas is supplied to the lower Al material, and N ２ Supply gas, The Mg vapor and N ２ React with gas to produce Mg ３ N ２ and producing said Mg ３ N ２ is precipitated into the inside of the molten upper Al material, and the Al of the molten upper Al material and the Mg ３ N ２ and reacting with each other to produce AlN, On the upper surface of the ceramic substrate, a first AlN layer (11a) in which AlN is formed so as to cover the upper surface of the ceramic substrate, a first Al-AlN layer (11b) containing Al of the upper Al material and AlN, and a first Al layer (11c) in which Al of the upper Al material is exposed on a surface are formed in that order; The nitriding promoter is precipitated inside the molten lower Al material, and the nitriding promoter promotes nitridation of Al in the lower Al material to generate AlN; A second AlN layer (12a) in which AlN is formed so as to cover the ceramic substrate, a second Al-AlN layer (12b) containing Al of the lower Al material and AlN, and a second Al layer (12c) in which Al of the lower Al material is exposed on the surface are formed in that order on the lower surface of the ceramic substrate. A method for producing an Al-AlN composite material.

3. The N ２ The amount of gas supplied was adjusted to ３ N ２ and further controlling the predetermined temperature in a plurality of stages; 3. The method for producing an Al-AlN composite material according to claim 1, wherein the first Al-AlN layer constitutes a comb-tooth-shaped AlN (11d) in which AlN is formed in a comb-tooth shape so as to protrude from the AlN layer.

4. A base (23) is disposed on the lower surface of the lower Al material, The method for producing an Al-AlN composite material described in claim 1 or claim 2, wherein the nitriding promoter settles inside the molten lower Al material and reaches the upper surface of the pedestal, and promotes peeling of the second Al layer from the pedestal after the second Al layer is formed.

5. 3. The method for producing an Al-AlN composite material according to claim 1, wherein the nitriding promoter has a specific gravity greater than that of the molten lower Al material.

6. The nitriding promoter is Al ２ O ３ 3. The method for producing an Al-AlN composite material according to claim 1, wherein the Al-AlN composite material is a mixture of Al and BN.

7. The nitriding promoter is ZrO ２ and SiO ２ 3. The method for producing an Al-AlN composite material according to claim 1, wherein the Al-AlN composite material is a mixture of the above.

8. The nitriding promoter is ZrO ２ and Al ２ O ３ 3. The method for producing an Al-AlN composite material according to claim 1, wherein the Al-AlN composite material is a mixture of the above.

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