Alloy, fusible plug and nozzle

Abstract

This invention relates to alloys, fusible plugs, and nozzles. [Problem] To provide an alloy with an endothermic peak temperature of 85-90°C as obtained from DSC curves and high Vickers hardness, a fusible plug with an operating temperature of 85-90°C, and a nozzle with an operating temperature of 85-90°C. [Solution] The alloy has a composition of Bi: 47.0-49.0% by mass, Sb: 0.8-1.2%, and the balance being In. Furthermore, the fusible plug and nozzle incorporate this alloy and operate at a temperature of 85-90°C.

Description

Technical Field

[0001] This invention relates to alloys, fusible plugs, and nozzles. Background Technology

[0002] Previously, large refrigeration units were equipped with safety devices such as fusible plugs, based on Article 7, Paragraph 1, Item 8 of the Ministry of Economy, Trade and Industry's Refrigeration Safety Regulations, as mechanisms to prevent damage and / or destruction of the refrigeration unit. These safety devices were designed to operate in accordance with the refrigerants they were used with.

[0003] As refrigerants used in refrigeration equipment, HCFC (hydrochlorofluorocarbon, hydrochlorofluorocarbon, fluorocarbon) refrigerants and HFC (hydrofluorocarbon, fluorocarbon) refrigerants with low ozone-depleting coefficients are used. When refrigerants are used in refrigeration equipment, they condense, and therefore, according to Boyle-Charlie's law, both pressure and temperature rise. Furthermore, the temperature rise varies depending on the type of refrigerant. Therefore, the operating temperature of the fusible plug is determined by the type of refrigerant.

[0004] For example, HCFC22 (R22) is currently the most in-demand HCFC-based refrigerant. When using this refrigerant, the condensing pressure is 1.94 MPa, therefore the critical temperature of R22 reaches 96.2°C. When using this refrigerant, a fusible plug with an operating temperature range of approximately 95~100°C is required.

[0005] Furthermore, when using R407C, an HFC-based refrigerant, the condensing pressure is 2.11 MPa, thus the critical temperature of R407C reaches 85.6°C. Therefore, a fusible plug with an operating temperature range of approximately 90~95°C is used. Moreover, when R410a, an HCFC-based refrigerant with good compression efficiency, is selected as the refrigerant for refrigeration equipment, the condensing pressure of the refrigerant is 3.06 MPa, thus the critical temperature of R410a reaches 71.5°C. When using this refrigerant, a fusible plug with an operating temperature range of 70~75°C is used.

[0006] Thus, various low-melting-point alloys can be used in fusible plugs with a wide range of operating temperature zones. For example, Patent Document 1 discloses a Zn-Bi-In alloy used in fusible plugs operating at 70~75°C and 95~100°C. In this document, Sb is disclosed as an arbitrary element to improve creep properties.

[0007] Patent Document 2 discloses a Bi-Sb(-Sn)-In solder alloy with a melting temperature of 72±2℃. This document also discloses that Sb improves creep characteristics. Patent Document 3 discloses an In-Cu-Sb-Bi alloy operating at 69~75℃. The alloy described in this document must not contain Sn, and the improvement in creep characteristics was investigated similarly to Patent Documents 1 and 2.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 4032094

[0011] Patent Document 2: Japanese Patent Application Publication No. 2022-137831

[0012] Patent Document 3: Japanese Patent Application Publication No. 2011-127776 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In Patent Document 1, R407C is used as a refrigerant with a low ozone depletion coefficient, and an alloy with an operating temperature of 90-95°C is employed. However, HFC refrigerants containing R407C present the challenge of high global warming potential (GWP). Therefore, the 2016 Kigali Amendment to the Montreal Protocol established a phased target of reducing HFC refrigerants by 85% in terms of CO2 equivalent by 2036.

[0015] As a goal for this phase, it is planned that by 2025, refrigerants using R407C in Japanese refrigerators and similar equipment, which are subject to laws related to the rationalization and optimization of Freon-related management, will be replaced with refrigerants with a GWP of 1500 or less. However, R407C has a GWP of 1770, making it impossible to achieve this goal. R410a, an HCFC-based refrigerant, is envisioned for use in Patent Documents 2 and 3 based on its critical temperature. However, this refrigerant has a GWP of 2090, and like R407C, it also fails to meet this goal.

[0016] Therefore, R448A can be cited as an alternative refrigerant. This refrigerant has a GWP of 1380, which meets the target GWP value up to 2025. However, R448A has a critical temperature of 83.7°C, which is 2°C lower than the 85.6°C of R407C used in Patent Document 1.

[0017] For a fusible plug to function properly, a critical temperature difference of 2°C is extremely important. If R448A is used and the operating temperature is set to 90-95°C, it may cause malfunction. Furthermore, setting the operating temperature of R448A within this temperature range increases the internal pressure, which the alloy used in the fusible plug may not be able to withstand.

[0018] Therefore, in order to obtain a fusible plug suitable for R448A with a low ozone depletion factor and low GWP, an alloy with an operating temperature of 85~90℃ is required. Moreover, in order to achieve the operating temperature within this temperature range, an alloy with an endothermic peak of 85~90℃ is required in the thermal history (hereinafter referred to as "DSC curve") obtained by differential scanning calorimetry.

[0019] However, the inventions described in Patent Documents 1-3 do not evaluate the mechanical properties within the operating temperature range. Furthermore, these documents assume a prolonged period of high internal pressure to evaluate creep characteristics. Indeed, evaluating creep characteristics is appropriate when considering the refrigerant's condensation pressure.

[0020] However, with the warming trend in recent years, there is an increasing demand for rapid freezing performance in refrigeration equipment. At the same time, the rate of application of condensation pressure has increased dramatically, thus requiring high hardness of the alloy in addition to creep resistance. Furthermore, even in the case of nozzles, there is a need to increase the hardness of the fusible alloy. Therefore, considering the aforementioned stage objectives for mitigating the warming trend in recent years and / or the actual conditions of refrigeration equipment and nozzles, it is urgent to provide alloys with a specified operating temperature range and high hardness.

[0021] Therefore, the objective of this invention is to provide an alloy with an endothermic peak temperature of 85-90°C obtained from DSC curves and high Vickers hardness, a fusible plug with an operating temperature of 85-90°C, and a nozzle with an operating temperature of 85-90°C.

[0022] Solution for solving the problem

[0023] The inventors conducted further research on the alloys specifically disclosed in Patent Documents 1 to 3. As for the alloys disclosed in Patent Document 1, four compositions were studied: the In-48Bi-1Sb-0.2Zn alloy disclosed in Example 9 of Table 2 of Patent Document 1 (numerical values ​​represent mass percentages, hereinafter referred to as the first composition); the In-35Bi-1Sb-0.5Sn alloy disclosed in Example 8 of Table 1 of Patent Document 1 (hereinafter referred to as the second composition); the In-35Bi-1.0Sb-3.0Sn alloy disclosed in Figure 7 of Patent Document 2 (hereinafter referred to as the third composition); and the 65In-44Bi (balance)-0.5Sb-0.5Cu alloy disclosed in paragraph 0021 of Patent Document 3 (hereinafter referred to as the fourth composition). It should be noted that in the examples and comparative examples extracted from Patent Documents 1 to 3, when the element content is expressed as an integer, the first decimal place is treated as 0.

[0024] The first composition contains Zn, Sn, and Cu. The following conclusion was drawn: because the first composition contains Zn, the endothermic peak temperature increases. This is believed to be because the presence of Zn increases both the solidus and liquidus temperatures, thus increasing the endothermic peak temperature.

[0025] Patent document 3, paragraph 0019, discloses that the disclosed Sn-free In-Cu-Sb-Bi alloy can achieve the desired creep characteristics, and its fluidity is increased when filled with alloy, and it can suppress the formation of voids and / or strength deviations. Specifically, regarding the second and third components containing Sn, it is speculated that if the alloy with higher In and Bi content contains Sn, a Sn oxide film will form in the melt, reducing the fluidity of the molten alloy. Furthermore, it is also observed that the Vickers hardness is low due to the presence of Sn in the second component.

[0026] Furthermore, the following observation was made: the fourth component has poor Vickers hardness due to the presence of Cu. This is presumably due to the precipitation of coarse Cu-containing compounds.

[0027] Therefore, the inventors conducted a detailed study on In-Bi-Sb alloys that do not contain Zn, Sn, and Cu. Specifically, based on the binary equilibrium phase diagram of the elements constituting the alloy, the contents of Bi and Sb were studied in detail to achieve an endothermic peak temperature in the range of 85-90°C and an improved Vickers hardness.

[0028] The results yielded the following insights: when the Bi and Sb contents are within a specified range, the endothermic peak temperature reaches 85~90℃. However, it was also observed that even alloys with endothermic peak temperatures in this range may exhibit low Vickers hardness due to low Sb content.

[0029] In order to improve the Vickers hardness of In-Bi-Sb alloys with an endothermic peak temperature of 85-90°C, the inventors focused on the following aspects: Sb exists as InSb, and it is believed that the precipitation of this compound contributes to the increase in Vickers hardness. InSb remains sufficiently until the melting start point (the temperature at which the fusible plug and / or nozzle operates). Therefore, it is speculated that the Vickers hardness can be maintained up to a temperature slightly lower than the operating temperature of the fusible plug and / or nozzle. In view of the melting behavior of the alloy at such a temperature increase, the inventors studied in detail the content of each constituent element.

[0030] In order to improve Vickers hardness, the inventors focused on increasing the precipitation of InSb, a hard compound, in compounds containing Bi, Sb, and In. However, they found that in alloys with high Sb content, although Vickers hardness increased, the endothermic peak temperature exceeded 90°C. Furthermore, they found that alloys with increased Bi content to increase In₂Bi precipitation also exhibited the same effect: while Vickers hardness increased, the endothermic peak temperature exceeded 90°C.

[0031] Thus, the following observation was obtained: when obtaining an alloy with an endothermic peak temperature of 85-90°C, there is a tendency for adjusting the endothermic peak temperature to this temperature range to conflict with exhibiting high Vickers hardness. Therefore, the inventors conducted more detailed research and obtained the following observation: within a very narrow range of Bi and Sb contents, an alloy with an endothermic peak temperature of 85-90°C and exhibiting high Vickers hardness can be obtained, thereby completing the present invention. At the same time, the following observation was also obtained: a fusible plug with an operating temperature of 85-90°C and a nozzle with an operating temperature of 85-90°C can be obtained.

[0032] The present invention, derived from these insights, is described below.

[0033] (0) An alloy, characterized in that, by mass%, it comprises Bi: 47.0~49.0%, Sb: 0.8~1.2%, and the balance is In.

[0034] (1) An alloy, characterized in that it has an alloy composition of Bi: 47.0~49.0% by mass, Sb: 0.8~1.2% by mass, and the balance being In.

[0035] (2) A fusible plug, characterized in that it comprises the alloy described in (0) or (1) above, and has an operating temperature of 85~90°C.

[0036] (3) A nozzle, characterized in that it has the alloy described in (0) or (1) above as a fusible alloy, and the working temperature is 85~90℃. Attached Figure Description

[0037] Figure 1 This diagram illustrates an example of the fusible plug according to this embodiment. Figure 1 (a) is a top view. Figure 1 (b) is Figure 1 AA section view of (a).

[0038] Figure 2 A ternary diagram showing the alloy of this embodiment. Detailed Implementation

[0039] The present invention will now be described in more detail. In this specification, unless otherwise specified, "%" in relation to alloy composition refers to "mass %".

[0040] 1. Alloy

[0041] (1) Bi: 47.0~49.0%

[0042] Bi controls the endothermic peak temperature obtained from the DSC curve and contributes to the increase of Vickers hardness. Bi can increase Vickers hardness through the precipitation of In₂Bi. Furthermore, the endothermic peak temperature can be controlled by the amount of In₂Bi precipitation and the melting timing during alloy melting. If the Bi content exceeds 49.0%, the amount of In₂Bi precipitation is excessive, thus the endothermic peak temperature exceeds 90°C. The upper limit of the Bi content is 49.0% or less, preferably 48.5% or less, and more preferably 48.0% or less.

[0043] On the other hand, if the Bi content is less than 47.0%, the amount of In₂Bi precipitated is small, resulting in an endothermic peak temperature below 85°C and poor Vickers hardness. The lower limit of the Bi content is 47.0% or more, preferably 47.5% or more.

[0044] The preferred range for Bi is 47.0~48.0%.

[0045] (2) Sb: 0.8~1.2%

[0046] Similar to Bi, Sb controls the endothermic peak temperature obtained from the DSC curve and contributes to the increase of Vickers hardness. Sb can increase Vickers hardness through the precipitation of InSb. Furthermore, InSb remains sufficiently until the melting start point (the temperature at which the fusible plug and nozzle operate, appropriately referred to as the "fusible plug, etc."). Therefore, it can maintain Vickers hardness up to a temperature slightly lower than the operating temperature of the fusible plug, etc. Additionally, the endothermic peak temperature of Sb can be controlled by the amount of InSb precipitation and the timing of melting during alloy melting.

[0047] If the Sb content exceeds 1.2%, the amount of InSb precipitated will be large, and therefore the endothermic peak temperature will exceed 90°C. The upper limit of the Sb content is 1.2% or less, preferably 1.1% or less, and more preferably 1.0% or less.

[0048] On the other hand, if the Sb content is less than 0.8%, InSb precipitation strengthening cannot be observed, resulting in poor Vickers hardness. The lower limit for the Sb content is 0.8% or more, preferably 0.9% or more.

[0049] The preferred range for Sb is 0.9 to 1.1%.

[0050] (3) Balance: In

[0051] The balance of the alloy of the present invention is In. In addition to the elements described above, it may contain unavoidable impurities. The balance of the alloy of the present invention can be In and unavoidable impurities. Even when unavoidable impurities are present, the above-described effects are not affected. Furthermore, even if the elements described below are contained as unavoidable impurities, the above-described effects are not affected.

[0052] It should be noted that the alloy of this invention does not contain Cu, Zn, or Sn. The presence of Cu and Sn lowers the operating temperature and degrades the Vickers hardness. The presence of Zn raises the operating temperature.

[0053] (4) Equation (1) ~ Equation (2)

[0054] 40.0≤Bi / Sb≤59.5 (1)

[0055] 322≤(Bi+Sb)×Vickers hardness≤352 (2)

[0056] In equations (1) and (2) above, Bi and Sb represent the content of the above alloy composition in terms of mass%.

[0057] The elements constituting the alloy of the present invention preferably have an operating temperature of 85-90°C when used in applications such as fusible plugs, and a Vickers hardness of 6.7 Hv or higher. These depend on the Bi and Sb in the alloy constituting the present invention.

[0058] When the Vickers hardness of the alloy of the present invention satisfies equation (1), the precipitation amounts of In2Bi and InSb are appropriate, thus a high Vickers hardness of 6.7Hv or higher can be obtained. Furthermore, the operating temperature of the alloy of the present invention is 85~90°C, which is a slightly lower temperature range, therefore it is not necessary to increase the Vickers hardness to a necessary level. Within the specified operating temperature range, the total stoichiometry of elements caused by Vickers hardness and the balance of Vickers hardness satisfy equation (2), thus making it a more preferred alloy for applications such as fusible plugs in the aforementioned operating temperature range.

[0059] The upper limit of formula (1) is preferably 59.5 or less, more preferably 53.3 or less, even more preferably 49.0 or less, and particularly preferably 48.5 or less. The lower limit of formula (1) is preferably 40.0 or more, more preferably 43.6 or more, even more preferably 47.0 or more, and even more preferably 47.5 or more.

[0060] A further preferred range for formula (1) is 40.0 to 53.3, and particularly preferred is 47.0 to 48.0. The above upper and lower limits can respectively define more preferred ranges for formula (1).

[0061] The upper limit of formula (2) is preferably 352 or less, more preferably 346 or less, even more preferably 338 or less, even more preferably 335 or less, particularly preferably 330 or less, and most preferably 326 or less. The lower limit of formula (2) is preferably 322 or more, more preferably 323 or more, and even more preferably 324 or more.

[0062] A further preferred range for formula (2) is 323 to 346, and particularly preferred is 324 to 330. The above upper and lower limits can respectively define a more preferred range for formula (2).

[0063] In the calculations of equations (1) and (2), the values ​​shown in Table 1 below, which pertain to the measured values ​​of the alloy composition, are used. Regarding the values ​​calculated by equations (1) and (2), equation (1) is calculated to one decimal place, and equation (2) is calculated as an integer. This calculation rule is used in this application. Furthermore, all alloys must be treated in the same way, and therefore it can also be extended to calculations involving more alloys described in other documents, etc.

[0064] 2. Fusible plug

[0065] The fusible plug of the present invention is formed by sealing the blank by melting the alloy of the present invention in a hole located in the center of the blank. Depending on the shape of the blank, the fusible plug includes various forms such as single-thread type, double-thread type, tapered tube type, and multi-hole type.

[0066] The fusible plug of this invention operates at a temperature of 85~90°C. If the operating temperature is within this range, R448A refrigerant can be used. If the operating temperature is below 90°C, excessive internal pressure increase can be prevented, and internal pressure can be safely released. Furthermore, if the operating temperature is above 85°C, malfunction of the fusible plug can be prevented.

[0067] 3. Sprayer head

[0068] The sprinkler head of the present invention uses the alloy of the present invention as a fusible alloy, and has an operating temperature of 85~90°C. The sprinkler head is installed on the ceiling or other parts of a building and operates due to heat generated by a fire, spraying water to extinguish the fire. When the sprinkler head reaches its operating temperature due to a fire or other cause, the fusible alloy constituting the heat-sensitive working part of the sprinkler head melts, the valve opens, and water is sprayed. As an example of a sprinkler head, a rapid-response type can be cited.

[0069] Example

[0070] The present invention will be described through the following embodiments, but the present invention is not limited to the following embodiments.

[0071] To demonstrate the effectiveness of the present invention, the alloys listed in Table 1 were used to evaluate (1) solidus temperature, peak temperature and liquidus temperature; (2) operating temperature; and (3) Vickers hardness.

[0072] (1) Solidus temperature, peak temperature and liquidus temperature

[0073] For alloys with the compositions shown in Table 1, their respective temperatures were determined using DSC curves. The DSC curves were obtained using a Seiko Instruments DSC (model: Q2000) at atmospheric temperature with a heating rate of 5°C / min. The liquidus temperature was determined from the obtained DSC curves. Additionally, the solidus temperature was also evaluated using the DSC curves. Furthermore, the maximum endothermic peak was identified as the peak temperature from the obtained DSC curves.

[0074] (2) Operating temperature

[0075] use Figure 1 A fusible plug is made by filling a hole in the center of a single-threaded blank 1 with a molten alloy having the alloy compositions shown in Table 1, and then cooling and sealing it. This fusible plug is then installed in a compressor via the threaded portion 3, and a pressure of 3 MPa is applied. Next, the fusible plug connected to the compressor is placed in a water tank, and the water in the tank is heated. The temperature at which air is immediately expelled from the fusible plug in the water tank is measured as the operating temperature. If the operating temperature is within the range of 85~90°C, the desired operating temperature is considered to have been achieved.

[0076] (3) Vickers hardness

[0077] A cylindrical sample with a φ8mm × 12mm diameter was machined using a solder alloy with the alloy composition shown in Table 1. For this sample, a micro Vickers hardness tester (HM-100, manufactured by Mitutoyo) was used to measure 10 random points at room temperature under a load of 25g and a loading time of 30 seconds. The average value was taken as the Vickers hardness. If it was 6.6Hv or higher, the desired Vickers hardness was considered to have been achieved.

[0078] The results are shown in Table 1.

[0079] [Table 1]

[0080]

[0081] As shown in Table 1, the working temperature of Examples 1 to 9 is 85 to 90°C, and the Vickers hardness is above 6.6 Hv. Figure 2 A ternary diagram showing the alloy of this embodiment. Figure 2 The figures illustrate Examples 1-9 and Comparative Examples 1-4, where • represents an example and 〇 represents a comparative example. Figure 2 Within the gray range shown in Figure 10, an alloy with an endothermic peak temperature of 85~90℃ and a Vickers hardness of 6.6Hv or higher was obtained.

[0082] On the other hand, Comparative Example 1, due to its low Bi content, had an operating temperature below 85°C and poor Vickers hardness. Comparative Example 2, due to its high Bi content, had an operating temperature exceeding 90°C. Comparative Example 3, due to its low Sb content, had poor Vickers hardness. Comparative Example 4, due to its high Sb content, had an operating temperature exceeding 90°C. Comparative Example 5, due to its low Bi content, had an operating temperature significantly lower than 85°C, and due to its high In content, also had poor Vickers hardness.

[0083] Comparative Example 6 has low Bi and Sb content and contains Cu, therefore its operating temperature is below 85°C and its Vickers hardness is poor. Comparative Example 7 contains Zn, therefore its operating temperature exceeds 90°C. Comparative Examples 8 and 9 have low Bi content and contain Sn, therefore their operating temperatures are below 85°C and their Vickers hardness is poor.

[0084] Industrial availability

[0085] The alloy of the present invention can be used not only as a fusible plug in the protective device of a refrigeration unit, but also as an alloy for a nozzle that is constantly subjected to pressure. Specifically, the alloy of the present invention can be used as a fusible alloy that constitutes the heat-sensitive working part assembled in the nozzle.

[0086] Explanation of reference numerals in the attached figures

[0087] 1. Billet, 2. Alloy, 3. Threaded section, 10. Range.

Claims

1. An alloy, characterized in that, It has an alloy composition of Bi: 47.0~49.0% by mass, Sb: 0.8~1.2% and balance In, and a Vickers hardness of 6.6Hv or higher.

2. A fusible plug, characterized in that, The alloy according to claim 1 has a working temperature of 85~90℃.

3. A nozzle, characterized in that, The alloy described in claim 1 is a fusible alloy with a working temperature of 85~90℃.

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