Brazing material, manifold, and brazing method

Abstract

To provide a brazing filler metal, a manifold and a brazing method capable of suppressing the occurrence of cracks in the brazing filler metal.SOLUTION: Disclosed is a brazing material (1) which contains 40 to 60 mass% of Zn, 39.5 to 56.5 mass% of Al, 0.5 to 3.5 mass% of Si and unavoidable impurities.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a brazing material, a manifold, and a brazing method, and more particularly to a brazing material, a manifold, and a brazing method containing Al, Zn, and Si. [Background technology]

[0002] BACKGROUND ART A brazing material containing Al, Zn, and Si and a brazing method are known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a brazing filler metal used for brazing aluminum, which contains 4% by mass to 12% by mass of Si, 15% by mass to 55% by mass of Zn, and 0.2% by mass to 2.0% by mass of Cu, with the remainder being aluminum and unavoidable impurities. In Patent Document 1, Si and Zn are added to the brazing filler metal to lower the melting point of the brazing filler metal. Furthermore, if the Si content is less than 4% by mass, it is difficult to obtain the effect of lowering the melting point of the brazing filler metal, so the brazing filler metal contains 4% by mass or more of Si. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-230890 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the brazing filler metal contains a large amount of Si as in Patent Document 1, when the molten brazing filler metal solidifies, a large amount of Si crystals, which are harder than Al and Zn, precipitate in the brazing filler metal. This can cause cracks to form in the brazing filler metal, originating from the Si crystals.

[0006] Furthermore, brazing filler metal may be used to braze a refrigerant flow path to a cover member. In recent years, development of new refrigerants (new refrigerants), such as propane gas and carbon dioxide gas, which have less impact on the environment, has been underway. These new refrigerants have higher pressures than the refrigerants currently used in automotive air conditioners, such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs). Therefore, if cracks occur in the brazing filler metal that forms the refrigerant flow path, the refrigerant (gas) may leak from the cracked area. Therefore, there is a need to prevent cracks from occurring in the brazing filler metal.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a brazing material, a manifold, and a brazing method that are capable of suppressing the occurrence of cracks in the brazing material. [Means for solving the problem]

[0008] In order to achieve the above object, the brazing filler metal in a first aspect of the present invention contains 40% by mass or more and 60% by mass or less of Zn, 39.5% by mass or more and 56.5% by mass or less of Al, 0.5% by mass or more and 3.5% by mass or less of Si, and inevitable impurities.

[0009] The brazing filler metal according to a first aspect of the present invention contains 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities. Since the Si content is 3.5% by mass or less, an increase in the amount of Si crystals that precipitate after the brazing filler metal solidifies can be suppressed. As a result, cracking of the brazing filler metal can be suppressed. Furthermore, the inventors have found through experiments (Examples) described below that the melting temperature of the brazing filler metal can be sufficiently lowered by setting the Si content to 0.5% by mass or more. Furthermore, because the brazing filler metal is less likely to crack, leakage of the refrigerant (gas) flowing through the refrigerant flow path can be suppressed when the brazing filler metal is used to braze a refrigerant flow path to a cover member.

[0010] A manifold according to a second aspect of the present invention includes a refrigerant flow path through which a refrigerant flows, a cover member that covers the refrigerant flow path, and a brazing filler metal that joins the refrigerant flow path and the cover member, the brazing filler metal containing 40% by mass or more and 60% by mass or less of Zn, 39.5% by mass or more and 56.5% by mass or less of Al, 0.5% by mass or more and 3.5% by mass or less of Si, and inevitable impurities.

[0011] A manifold according to a second aspect of the present invention includes a brazing filler metal for joining the refrigerant flow passage and the cover member, as described above. The brazing filler metal contains 40% to 60% by mass of Zn, 39.5% to 56.5% by mass of Al, 0.5% to 3.5% by mass of Si, and inevitable impurities. Since the Si content is 3.5% or less, an increase in the amount of Si crystals that precipitate after the brazing filler metal solidifies can be suppressed. As a result, cracking of the brazing filler metal can be suppressed. Furthermore, the inventors have found through experiments (Examples) described below that the melting temperature of the brazing filler metal can be sufficiently lowered by setting the Si content to 0.5% by mass or more. Furthermore, because the brazing filler metal is less likely to crack, a manifold can be provided that can suppress leakage of the refrigerant (gas) flowing through the refrigerant flow passage when the brazing filler metal is used to braze the refrigerant flow passage and the cover member.

[0012] A brazing method according to a third aspect of the present invention includes a step of melting a mixture of a brazing filler metal containing 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities, and a fluoride-based flux, and brazing a base material and objects to be joined.

[0013] In a third aspect of the present invention, the brazing material includes the steps of melting a brazing material containing 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities, and activating a fluoride-based flux mixture to braze a base material and a workpiece. Since the Si content is 3.5% by mass or less, the Si content can be reduced, thereby reducing the amount of Si crystals that precipitate after the brazing material solidifies. Furthermore, the inventors have found through experiments (Examples) described below that the melting temperature of the brazing material can be sufficiently lowered by increasing the Si content to 0.5% by mass or more. Furthermore, since the use of a fluoride-based flux has a higher activation temperature than a chloride-based flux, it is not necessary to increase the Si content to significantly lower the melting temperature of the brazing material. As a result, a brazing method can be provided that can reduce the Si content and thereby suppress cracking of the brazing material. Furthermore, since cracks are less likely to occur in the brazing material, when the refrigerant flow path and the cover member are brazed together, leakage of the refrigerant (gas) flowing through the refrigerant flow path can be suppressed. [Effects of the Invention]

[0014] As described above, the present invention can provide a brazing material, a manifold, and a brazing method that can suppress the occurrence of cracks in the brazing material. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a front view showing a state in which the objects to be joined are brazed to the base material. [Figure 2] FIG. 2 is a top view showing a state in which objects to be joined are brazed to a base material. [Figure 3] 1 is a graph showing the relationship between the Zn content and the Si content and the temperature. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0017] The brazing material, manifold, and brazing method according to this embodiment will be described with reference to FIGS.

[0018] As shown in FIG. 1, the brazing material 1 is used to join a base material 10 and an object to be joined 20. The brazing material 1 is solid. For example, the brazing material 1 is formed in a rod shape. The brazing material 1 melts when heated and is flowed between the base material 10 and the object to be joined 20. The molten brazing material 1 then solidifies, thereby brazing the base material 10 and the object to be joined 20. Note that, for convenience, the thickness of the brazing material 1 is depicted as being large, but the thickness may be small.

[0019] As shown in FIG. 2 , in this embodiment, the base material 10 is, for example, a manifold mounted on a vehicle such as an automobile. The manifold includes a refrigerant flow path 10a included in a cooling system for the vehicle. The object to be joined 20 is, for example, a cover member that covers the refrigerant flow path 10a formed in the manifold. The manifold is, for example, made of aluminum die-casting formed by die-casting aluminum. The aluminum die-casting is, for example, ADC12. The object to be joined 20 is, for example, formed by pressing an aluminum alloy in the A3000 series. The base material 10 and the object to be joined 20 are each cleaned, combined, and then brazed with a brazing material 1. In FIG. 2 , the brazing material 1 is indicated by hatching. FIG. 2 also shows the outline of the object to be joined 20. In FIG. 2 , the brazing material 1 and the refrigerant flow path 10a are shown visible from the outside, but the object to be joined 20 is brazed to cover the brazing material 1 and the refrigerant flow path 10a. The melting point of the base material 10 and the melting point of the object to be joined 20 may be the same temperature or may be different temperatures.

[0020] In recent years, new refrigerants (new refrigerants) with less environmental impact have been widely developed as refrigerants flowing through the refrigerant flow path 10a of the manifold. New refrigerants include propane gas, carbon dioxide gas, and the like. These new refrigerants have higher pressures than refrigerants currently used in automotive air conditioners, such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs). For example, while the limit pressure of conventional HFOs is approximately 3.382 MPa, the limit pressure of new refrigerants, propane gas, is 4.2 MPa, and the limit pressure of carbon dioxide gas is 7.4 MPa. Therefore, if cracks occur in the brazing filler metal when the refrigerant pressure is high, there is a risk of refrigerant (gas) leakage. Therefore, it is necessary to suppress cracks in the brazing filler metal used in the manifold. As shown in the examples described below, the brazing filler metal 1 of the present invention can suppress cracks in the brazing filler metal 1 and can be used in manifolds that use new refrigerants.

[0021] The brazing filler metal 1 contains Al, Zn, and Si. The brazing filler metal 1 may also contain inevitable impurities in addition to Al, Zn, and Si.

[0022] The Zn content of the brazing filler material 1 is 40% by mass or more and 60% by mass or less, and preferably 52.5% by mass or more and 57.5% by mass or less.

[0023] The Al content of the brazing material 1 is 39.5 mass % or more and 56.5 mass % or less, and preferably 41.5 mass % or more and 46.5 mass % or less.

[0024] The Si content of the brazing material 1 is 0.5% by mass or more and 3.5% by mass or less, and preferably 0.5% by mass or more and 2.0% by mass or less. Since the Si content is 3.5% by mass or less, it is possible to prevent an increase in the amount of Si crystals that precipitate after the brazing material 1 solidifies. As a result, it is possible to prevent cracks from occurring in the brazing material 1.

[0025] The brazing filler metal 1 has a melting temperature that is equal to or lower than the melting point of the base material 10. By changing the ratio of the Al content, the Zn content, and the Si content, the melting temperature of the brazing filler metal 1 is adjusted to be lower than the melting point of the base material 10. In particular, since Zn and Si have the effect of lowering the melting temperature of the brazing filler metal 1, by decreasing the Si content to suppress the occurrence of cracks and increasing the Zn content, the desired melting temperature can be adjusted while suppressing the occurrence of cracks.

[0026] In this embodiment, the melting temperature of the brazing material 1 is 520° C. or higher and 550° C. or lower, and preferably 530° C. or higher and 550° C. or lower. This makes it possible to prevent the base material 10 from melting when brazing the base material 10 made of aluminum die-cast, which has a melting point of 560° C. or higher, to the joining object 20 made of an aluminum alloy.

[0027] A flux is used when brazing the base material 10 and the object to be joined 20. The flux melts and becomes activated when it reaches an activation temperature or higher. The activation of the flux removes an oxide film formed on the surface of the base material 10 to be brazed. The activation of the flux may also be configured to suppress oxidation of the base material 10. The flux may also be configured to suppress an increase in the protrusion amount of a convex portion formed at the brazing point by reducing the surface separation tension of the brazing material 1. The flux is selected in accordance with the melting temperature of the brazing material 1 so that the difference between the activation temperature of the flux and the melting temperature of the brazing material 1 is small or zero.

[0028] In this embodiment, the flux is a no-clean flux, which does not require a cleaning process after brazing. The no-clean flux is inactive after brazing and therefore does not react with or corrode the base material 10 and the workpieces 20. Therefore, it does not need to be cleaned and washed away. The no-clean flux is preferably a fluoride-based flux, and more preferably a cesium-fluoride-based flux containing cesium. For example, the cesium-fluoride-based flux is cesium tetrafluoroaluminate. The cesium-fluoride-based flux has a lower activation temperature than a flux containing no cesium. Unlike chloride-based fluxes, fluoride-based fluxes become inactive after melting, so cleaning after brazing is not required.

[0029] The activation temperature of the fluoride-based flux of this embodiment is, for example, 400° C. or higher and 550° C. or lower. The flux is, for example, a liquid and is poured onto the base material 10 and the objects to be joined 20. In another example, the flux may be a solid and used in a molten state, or may be mixed into the brazing material 1.

[0030] A brazing method will now be described. The brazing method includes a step of melting a brazing filler metal 1 containing Al, Zn, and 0.5 mass % to 3.5 mass % Si, activating a mixture of fluoride-based fluxes, and brazing a base material 10 and objects to be joined 20. In this embodiment, the brazing step includes a step of melting a brazing filler metal 1 having a melting temperature of 520°C to 550°C and activating a fluoride-based flux having an activation temperature of 400°C to 550°C to braze the base material 10 made of aluminum die-cast having a melting point of 560°C or higher to the objects to be joined 20.

[0031] In the brazing process, first, a flux and a brazing material 1 are poured onto the assembled base material 10 and the objects to be joined 20. The flux is then activated by heating, and an oxide film on the surface of the base material 10 is removed. The brazing material 1 is then melted by heating, thereby performing brazing. The brazing material 1 is heated to a temperature equal to or higher than the activation temperature of the flux, equal to or higher than the melting temperature of the brazing material 1, and lower than the melting points of the base material 10 and the objects to be joined 20. In this embodiment, the melting temperature of the brazing material 1 is 520°C or higher and 550°C or lower, the activation temperature of the flux is 400°C or higher and 550°C or lower, and the melting point of the base material 10 is 560°C or higher. Therefore, the brazing material 1 is heated to the melting temperature of the brazing material 1, which is 520°C or higher and 550°C or lower. After heating, the brazing material 1 is cooled to harden. The flux and the brazing material 1 do not need to be poured simultaneously onto the base material 10 and the objects to be joined 20; the flux may be poured first. In addition, the heating step may involve heating to activate the flux, followed by heating to melt the brazing material 1, or may involve both activating the flux and melting the brazing material 1. When heating to activate the flux and then heating to melt the brazing material 1 is performed, the material is heated to the activation temperature of the flux and then to the melting temperature of the brazing material 1.

[0032] (Example) FIG. 3 is a graph showing the state of the brazing filler metal 1 when the Zn content, Si content, and Al content are changed. In the graph of FIG. 3, the Zn content (mass%) is plotted on the horizontal axis, and the Si content (mass%) is plotted on the vertical axis. The Al content is calculated by subtracting the sum of the Zn content and the Si content from 100 mass%. The solid line in the graph indicates the eutectic line (520°C), and the dashed line indicates the liquidus line (550°C). In the graph of FIG. 3, the temperature at which the eutectic can occur (crystallization of Al, Zn, and Si at approximately the same temperature) is lower than 520°C in the region above the eutectic line, and the melting temperature at which the brazing filler metal can be used is lower than 520°C. In the region below the liquidus line, the temperature at which the brazing filler metal becomes liquid is higher than 550°C, and the melting temperature of the brazing filler metal is higher than 550°C. Therefore, the brazing filler metal 1 having Zn content, Si content, and Al content between the eutectic line and the liquidus line has a melting temperature of 520°C or higher and 550°C or lower.

[0033] The present inventors investigated the brazing of a workpiece 20 using a brazing material 1 composed of Zn, Si, and Al to a base material 10 made of aluminum die-casting with a melting point of 568°C. In this case, the melting temperature of the brazing material 1 must be lower than the melting point of the aluminum die-casting. Furthermore, if the heating temperature during brazing is set to the melting temperature of the brazing material 1, an excessively high heating temperature may cause bubbles to form due to residual gas inside the base material 10, resulting in blisters on the surface. Furthermore, an excessively low heating temperature may cause the brazing material 1 to undergo eutectic formation, preventing the formation of a portion known as a fillet (a convex portion). Therefore, the present inventors set the melting temperature of the brazing material 1 to be 520°C or higher and 550°C or lower. From the graph in FIG. 3, they selected combinations of the Zn content, Si content, and Al content so that the melting temperature was in the range of 520°C or higher and 550°C or lower. These results were used to create Examples 1 to 22. Examples 1 to 22 are shown in Tables 1 to 4.

[0034] [Table 1]

[0035] As shown in Example 1 of Table 1, by adjusting the Zn content to 40.0 mass%, the Al content to 56.5 mass%, and the Si content to 3.5 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (550°C). As shown in Example 2, by adjusting the Zn content to 42.5 mass%, the Al content to 54.0 mass%, and the Si content to 3.5 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 3, by adjusting the Zn content to 42.5 mass%, the Al content to 54.5 mass%, and the Si content to 3.0 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (550°C).

[0036] As shown in Example 4, by adjusting the Zn content to 45.0 mass%, the Al content to 52.0 mass%, and the Si content to 3.0 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C or higher and 550°C or lower (540°C).Also, as shown in Example 5, by adjusting the Zn content to 45.0 mass%, the Al content to 52.5 mass%, and the Si content to 2.5 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C or higher and 550°C or lower (550°C).

[0037] [Table 2]

[0038] As shown in Example 6 of Table 2, by adjusting the Zn content to 47.5 mass%, the Al content to 49.5 mass%, and the Si content to 3.0 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (530°C). As shown in Example 7, by adjusting the Zn content to 47.5 mass%, the Al content to 50.0 mass%, and the Si content to 2.5 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 8, by adjusting the Zn content to 47.5 mass%, the Al content to 50.5 mass%, and the Si content to 2.0 mass%, the melting temperature of the brazing filler metal 1 can be adjusted to a range of 520°C to 550°C (550°C).

[0039] Furthermore, as shown in Example 9, by adjusting the Zn content to 50.0 mass%, the Al content to 47.5 mass%, and the Si content to 2.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (530°C). As shown in Example 10, by adjusting the Zn content to 50.0 mass%, the Al content to 48.0 mass%, and the Si content to 2.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 11, by adjusting the Zn content to 50.0 mass%, the Al content to 48.5 mass%, and the Si content to 1.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (550°C).

[0040] [Table 3]

[0041] As shown in Example 12 of Table 3, by adjusting the Zn content to 52.5 mass%, the Al content to 45.5 mass%, and the Si content to 2.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (530°C). As shown in Example 13, by adjusting the Zn content to 52.5 mass%, the Al content to 46.0 mass%, and the Si content to 1.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 14, by adjusting the Zn content to 52.5 mass%, the Al content to 46.5 mass%, and the Si content to 1.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (550°C). As shown in Example 15, by adjusting the Zn content to 55.0 mass%, the Al content to 43.5 mass%, and the Si content to 1.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (530°C). As shown in Example 16, by adjusting the Zn content to 55.0 mass%, the Al content to 44.0 mass%, and the Si content to 1.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 17, by adjusting the Zn content to 55.0 mass%, the Al content to 44.5 mass%, and the Si content to 0.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (550°C).

[0042] [Table 4]

[0043] As shown in Example 18 of Table 4, by adjusting the Zn content to 57.5 mass%, the Al content to 41.5 mass%, and the Si content to 1.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (530°C). As shown in Example 19, by adjusting the Zn content to 57.5 mass%, the Al content to 42.0 mass%, and the Si content to 0.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (540°C). As shown in Example 20, by adjusting the Zn content to 60.0 mass%, the Al content to 38.5 mass%, and the Si content to 1.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (520°C). As shown in Example 21, by adjusting the Zn content to 60.0 mass%, the Al content to 39.0 mass%, and the Si content to 1.0 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (525°C). As shown in Example 22, by adjusting the Zn content to 60.0 mass%, the Al content to 39.5 mass%, and the Si content to 0.5 mass%, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C (530°C). From the above, when adjusting the melting temperature of the brazing filler material 1 to a range of 520°C to 550°C, by increasing the Zn content, the melting temperature of the brazing filler material 1 can be adjusted to a range of 520°C to 550°C even if the Si content is reduced.

[0044] The brazing filler metals not included between the eutectic line and the liquidus line in Fig. 3 were designated as Comparative Examples 1 to 6. Comparative Examples 1 to 6 are shown in Table 5.

[0045] [Table 5]

[0046] As shown in Comparative Example 1 in Table 5, when the Zn content was adjusted to 40.0 mass%, the Al content was adjusted to 56.0 mass%, and the Si content was adjusted to 4.0 mass%, the melting temperature of the brazing filler metal was 518°C. Furthermore, as shown in Comparative Example 2, when the Zn content was adjusted to 42.5 mass%, the Al content was adjusted to 53.5 mass%, and the Si content was adjusted to 4.0 mass%, the melting temperature of brazing filler metal 1 was 516°C. For these reasons, when the Si content is 4.0 mass% or more, the melting temperature may be less than 520°C. Furthermore, as shown in Comparative Example 3, when the Zn content was adjusted to 47.5 mass%, the Al content was adjusted to 52.5 mass%, and the Si content was 0 mass%, the melting temperature of the brazing filler metal was 558°C. As shown in Comparative Example 4, the melting temperature of a brazing material in which the Zn content is adjusted to 50.0 mass%, the Al content is adjusted to 50.0 mass%, and the Si content is 0 mass% is 556°C. As shown in Comparative Example 5, the melting temperature of a brazing material in which the Zn content is adjusted to 52.5 mass%, the Al content is adjusted to 47.5 mass%, and the Si content is 0 mass% is 554°C. As shown in Comparative Example 6, the melting temperature of a brazing material in which the Zn content is adjusted to 55.0 mass%, the Al content is adjusted to 45.0 mass%, and the Si content is 0 mass% is 552°C. From the above, when the Si content is 0, the melting temperature may exceed 550°C.

[0047] The inventors of the present application conducted a test in which the brazing filler metals 1 of Examples 14 to 16 were used to braze ADC12 (aluminum die-cast) and A3003 (aluminum alloy).

[0048] With the brazing filler metals 1 of Examples 14 to 16, cracks did not occur at the brazed joint between ADC12 (aluminum die-cast) and A3003 (aluminum alloy), and ADC12 (aluminum die-cast) and A3003 (aluminum alloy) were able to be sufficiently joined together. From the above, the inventors have found that the brazing filler metal 1 having a melting temperature in the range of 520°C to 550°C can braze the base material 10 and the object 20 to be joined without causing cracks.

[0049] Furthermore, as described above, brazing filler metals used in components that use new refrigerants are required to suppress the occurrence of cracks in the brazing filler metal. As shown in the examples, the inventors of the present invention have found that brazing filler metal 1 of the present invention can suppress the occurrence of cracks, unlike conventional brazing filler metals, and therefore can be used to braze components that use new refrigerants (for example, manifolds).

[0050] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0051] In this embodiment, as described above, the brazing material 1 contains 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities. Since the Si content is 3.5% by mass or less, an increase in the amount of Si crystals that precipitate after the brazing material 1 solidifies can be suppressed. As a result, the occurrence of cracks in the brazing material 1 can be suppressed. Furthermore, the inventors of the present application have found through experiments (Examples) that the melting temperature of the brazing material 1 can be sufficiently lowered by setting the Si content to 0.5% by mass or more. Furthermore, because the brazing material 1 is less likely to crack, leakage of the refrigerant (gas) flowing through the refrigerant flow path 10a can be suppressed when the brazing material 1 is used to braze the refrigerant flow path 10a to a cover member.

[0052] In this embodiment, as described above, the melting temperature is 520°C or higher and 550°C or lower. Because the melting temperature of the brazing filler metal 1 is 550°C or lower, even when a base material 10 having a melting point between 560°C and 600°C is used as the base material 10 to be brazed, brazing can be performed without melting the base material 10. Furthermore, because the melting temperature of the brazing filler metal 1 is 520°C, a fluoride-based flux having an activation temperature higher than 520°C can be used during brazing. As a result, unlike chloride-based fluxes that may react with the base material 10 after brazing, fluoride-based fluxes are inactivated after melting, thereby suppressing corrosion of the base material 10.

[0053] In this embodiment, as described above, the brazing material contains 52.5 to 57.5 mass% of Zn, 41.5 to 46.5 mass% of Al, and 0.5 to 2.0 mass% of Si. The inventors of the present application have found through experiments (Examples) that this allows the melting temperature of the brazing material 1 to be sufficiently low and makes it less likely for cracks to occur when the brazing material 1 solidifies.

[0054] In this embodiment, the manifold includes a refrigerant flow path 10a through which a refrigerant flows, a cover member covering the refrigerant flow path 10a, and a brazing material 1 connecting the refrigerant flow path 10a and the cover member. The brazing material 1 contains 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities. Since the Si content is 3.5% by mass or less, an increase in the amount of Si crystals that precipitate after the brazing material 1 solidifies can be suppressed. As a result, cracking of the brazing material 1 can be suppressed. Furthermore, the inventors of the present application have found through experiments (Examples) that the melting temperature of the brazing material 1 can be sufficiently lowered by setting the Si content to 0.5% by mass or more. Furthermore, because the brazing material 1 is less likely to crack, a manifold can be provided that can suppress leakage of the refrigerant (gas) flowing through the refrigerant flow path 10a when the brazing material 1 is used to braze the refrigerant flow path 10a to the cover member.

[0055] In this embodiment, the method includes the steps of melting the brazing filler metal 1 containing 40% by mass to 60% by mass of Zn, 39.5% by mass to 56.5% by mass of Al, 0.5% by mass to 3.5% by mass of Si, and inevitable impurities, and activating the fluoride-based flux mixture to braze the base material 10 and the object to be joined 20. Since the Si content is 3.5% by mass or less, the Si content can be reduced, thereby reducing the amount of Si crystals that precipitate after the brazing filler metal 1 solidifies. Furthermore, the inventors have found through experiments (Examples) that the melting temperature of the brazing filler metal 1 can be sufficiently lowered by setting the Si content to 0.5% by mass or more. Furthermore, since the use of a fluoride-based flux has a higher activation temperature than a chloride-based flux, it is not necessary to increase the Si content to significantly lower the melting temperature of the brazing filler metal 1. As a result, the Si content can be reduced, thereby providing a brazing method that can suppress cracking of the brazing filler metal. Furthermore, since the brazing material 1 is less likely to crack, when the refrigerant flow path 10a and the cover member are brazed together, leakage of the refrigerant (gas) flowing through the refrigerant flow path 10a can be suppressed.

[0056] (Additional note 1) In this embodiment, as described above, the melting temperature is 530° C. or higher and 550° C. or lower. As a result, even if a base material 10 having a melting point between 560° C. and 600° C. is used as the base material 10 to be brazed, brazing can be performed without melting the base material 10.

[0057] (Additional note 2) In this embodiment, as described above, the brazing process includes a step of melting the brazing filler metal 1, which is made of aluminum die-cast and has a melting point of 560°C or higher, and the workpieces 20 to be joined together by melting the brazing filler metal 1, which has a melting temperature of 520°C or higher and 550°C or lower, and activating a fluoride-based flux mixture. By using the brazing filler metal 1, which has a melting temperature below the melting point of the aluminum die-cast, and the fluoride-based flux, which has an activation temperature below the melting point of the aluminum die-cast, the base material 10 and the workpieces 20 to be joined can be brazed together without melting the aluminum die-cast base material 10. Furthermore, unlike chloride-based fluxes, the fluoride-based flux is inactivated after melting, thereby suppressing corrosion of the base material 10. As a result, the base material 10 and the workpieces 20 to be joined can be brazed together with sufficient joint strength.

[0058] [Variations] The above-described embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above-described embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0059] For example, in the above embodiment, an example was shown in which the base material is a manifold and the objects to be joined are cover members, but the present invention is not limited to this. In the present invention, the objects to be joined may be members other than a manifold, and the objects to be joined may be parts other than a cover member. For example, the base material may be a substrate, and the objects to be joined may be electronic components attached to the substrate.

[0060] In the above embodiment, the brazing material is used to braze aluminum die-cast and aluminum alloy, but the present invention is not limited to this. In the present invention, the brazing material may be used to join metals other than aluminum, such as stainless steel.

[0061] In the above embodiment, the base material is an aluminum die-cast of ADC12, but the present invention is not limited to this. In the present invention, the base material may be another aluminum die-cast, such as ADC10.

[0062] In the above embodiment, the melting temperature of the brazing material is 520°C or higher and 550°C or lower, but the present invention is not limited to this. In the present invention, the melting point differs depending on the material of the base material and the material of the joining object 20, so the melting temperature of the brazing material may be different from 520°C or higher and 550°C or lower.

[0063] In the above embodiment, the activation temperature of the flux is 400° C. or higher and 550° C. or lower, but the present invention is not limited to this. In the present invention, the activation temperature of the flux may be changed in accordance with the melting temperature of the brazing material. [Explanation of symbols]

[0064] 1 Brazing material, 10 Base material, 20 Object to be joined

Claims

1. A brazing filler metal containing 40% by mass or more and 60% by mass or less of Zn, 39.5% by mass or more and 56.5% by mass or less of Al, 0.5% by mass or more and 3.5% by mass or less of Si, and inevitable impurities.

2. The brazing material according to claim 1, wherein the melting temperature is 520°C or higher and 550°C or lower.

3. The joining tool is configured to join a base material and an object to be joined, The braze of claim 1 , wherein the melting temperature is less than the melting temperature of the base material.

4. 2. The brazing filler metal according to claim 1, containing 52.5 mass% or more and 57.5 mass% or less of Zn, 41.5 mass% or more and 46.5 mass% or less of Al, 0.5 mass% or more and 2.0 mass% or less of Si, and inevitable impurities.

5. a refrigerant flow path through which a refrigerant flows, a cover member that covers the refrigerant flow path, and a brazing material that joins the refrigerant flow path and the cover member, The manifold, wherein the brazing material contains 40 mass % or more and 60 mass % or less of Zn, 39.5 mass % or more and 56.5 mass % or less of Al, 0.5 mass % or more and 3.5 mass % or less of Si, and inevitable impurities.

6. A brazing method comprising the steps of melting a brazing filler metal containing 40% by mass or more and 60% by mass or less of Zn, 39.5% by mass or more and 56.5% by mass or less of Al, 0.5% by mass or more and 3.5% by mass or less of Si, and inevitable impurities, and activating a mixture of a fluoride-based flux to braze a base material and objects to be joined.

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