Alloys, fusible plugs, and sprinkler heads

Abstract

The present invention provides an alloy having an endothermic peak temperature of 85-90°C obtained from a DSC curve and high Vickers hardness, a fusible plug with an operating temperature of 85-90°C, and a sprinkler head with an operating temperature of 85-90°C. [Solution] The alloy has an alloy composition consisting of Bi: 47.0-49.0% by mass, Sb: 0.8-1.2%, and the remainder being In. Fusible plugs and sprinkler heads are made of this alloy and have an operating temperature of 85-90°C.

Description

Technical Field

[0005] ,

[0004] , , , , , ,

[0003] ,

[0006]

[0001] The present invention relates to an alloy, a fusible plug, and a sprinkler head.

Background Art

[0002] Conventionally, large refrigeration devices are equipped with safety devices such as fusible plugs as a mechanism for preventing damage and destruction of refrigerators based on Article 7, Paragraph 1, Item 8 of the Refrigeration Safety Regulations of the Ministry of Economy, Trade and Industry. This safety device is designed to operate suitable for the refrigerant it uses.

[0003] As refrigerants used in refrigeration devices and the like, HCFC (Hydro, Chloro, Fluoro-Carbons) - based refrigerants and further HFC (Hydro, Fluoro-Carbons) - based refrigerants with a small ozone depletion potential are used. When the refrigerant is used in a refrigeration device, since the refrigerant is condensed, according to Boyle's law, the pressure rises and the temperature also rises. And the rising temperature varies depending on the type of refrigerant. Therefore, the operating temperature of the fusible plug is determined according to the type of refrigerant.

[0004] For example, as the refrigerant with the highest demand among HCFC - based refrigerants at present, HCFC22 (R22) can be mentioned. When this refrigerant is used, since the condensation pressure is 1.94 MPa, the critical temperature of R22 is 96.2 °C. When this refrigerant is used, a fusible plug with an operating temperature range of about 95 - 100 °C is applied.

[0005] Also, when using R407C of HFC - based refrigerant, since the condensation pressure is 2.11 MPa, the critical temperature of R407C is 85.6 °C. Therefore, a fusible plug with an operating temperature range of about 90 - 95 °C is applied. Furthermore, when R410a of HCFC - based refrigerant with good compression efficiency is selected as the refrigerant for the refrigeration device, since the condensation pressure of the refrigerant is 3.06 MPa, the critical temperature of R410a is 71.5 °C. When this refrigerant is used, a fusible plug with an operating temperature range of 70 - 75 °C is applied.

[0006] Thus, various low-melting-point alloys are used for fusible plugs that have a range of operating temperatures. For example, Patent Document 1 discloses a Zn-Bi-In alloy used for fusible plugs that operate at 70-75°C and 95-100°C. The same document also discloses Sb as an optional 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 properties. Patent Document 3 discloses an In-Cu-Sb-Bi alloy that operates at 69~75℃. The alloy described in this document must not contain Sn, and, similar to Patent Documents 1 and 2, improvement of creep properties is being considered. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 4032094 [Patent Document 2] Japanese Patent Publication No. 2022-137831 [Patent Document 3] Japanese Patent Publication No. 2011-127776 [Overview of the project] [Problems that the invention aims to solve]

[0009] Patent Document 1 uses R407C as a refrigerant with a low ozone depletion potential, and employs an alloy with an operating temperature of 90-95°C. However, HFC refrigerants, including R407C, have the drawback of having a high global warming potential (GWP). For this reason, the 2016 Kigali Amendment to the Montreal Protocol set a phased target of reducing HFC refrigerants by 85% in terms of CO2 equivalent by 2036.

[0010] As a target for this phase, Japan's Fluorocarbon Emission Control Law aims to replace R407C in refrigerators and other equipment with refrigerants having a GWP of 1500 or less by 2025. However, R407C has a GWP of 1770, making it impossible to achieve this target. R410a, an HCFC refrigerant, is expected to be used in Patent Documents 2 and 3 due to its critical temperature. However, this refrigerant has a GWP of 2090, and like R407C, it will not achieve this target.

[0011] Therefore, R448A can be cited as an alternative refrigerant. This refrigerant has a GWP of 1380, which can achieve the target GWP value by 2025. However, the critical temperature of R448A is 83.7°C, which is 2°C lower than the 85.6°C of R407C used in Patent Document 1.

[0012] For a fusible plug to function properly, a critical temperature difference of 2°C is extremely large. Setting the operating temperature to 90-95°C using R448A could lead to malfunction. Furthermore, setting the operating temperature of R448A in this temperature range would increase the internal pressure, potentially causing the alloy used in the fusible plug to be unable to withstand the pressure.

[0013] Thus, in order to obtain a fusible plug applicable to R448A, which has a low ozone depletion potential and low GWP, an alloy with an operating temperature of 85-90°C is required. Furthermore, for the operating temperature to be in this temperature range, the alloy must have an endothermic peak at 85-90°C in the thermal history obtained by suggestive scanning calorimetry (hereinafter referred to as the "DSC curve").

[0014] However, the inventions described in Patent Documents 1 to 3 do not evaluate the mechanical properties in this temperature range. Furthermore, these documents evaluate creep characteristics assuming that the internal pressure remains high for a long period of time. Certainly, considering the condensation pressure of the refrigerant, it is reasonable to evaluate creep characteristics.

[0015] However, with the recent increase in global warming, there is a growing demand for rapid freezing performance in refrigeration equipment. Consequently, the rate at which condensation pressure is applied increases rapidly, and in addition to creep properties, high hardness of the alloy is also required. Furthermore, even when used in sprinkler heads, improved hardness of the fusible alloy is needed. Thus, considering the aforementioned targets for curbing recent global warming, as well as the realities of refrigeration equipment and sprinkler heads, there is an urgent need to provide alloys with a specified operating temperature range and high hardness.

[0016] Therefore, the object of the present invention is to provide an alloy having an endothermic peak temperature of 85-90°C obtained from a DSC curve and high Vickers hardness, a fusible plug with an operating temperature of 85-90°C, and a sprinkler head with an operating temperature of 85-90°C. [Means for solving the problem]

[0017] The inventors re-examined the alloys specifically disclosed in Patent Documents 1 to 3. As alloys disclosed in Patent Document 1, four compositions were examined: In-48Bi-1Sb-0.2Zn alloy (numerical values ​​represent mass %) disclosed in Example 9, Table 2, Patent Document 1 (hereinafter referred to as the first composition); In-35Bi-1Sb-0.5Sn alloy (hereinafter referred to as the second composition) disclosed in Example 8, Table 1, Patent Document 1; In-35Bi-1.0Sb-3.0Sn alloy (hereinafter referred to as the third composition) disclosed in Figure 7, Patent Document 2; and 65In-44Bi(remainder)-0.5Sb-0.5Cu alloy (hereinafter referred to as the fourth composition) disclosed in paragraph 0021, Patent Document 3. In the examples and comparative examples extracted from Patent Documents 1 to 3, if the element content was expressed as an integer, the first decimal place was treated as 0.

[0018] These alloys contain Zn, Sn, and Cu, respectively. It was found that the first composition, due to the presence of Zn, exhibits an increased endothermic peak temperature. This is thought to be because the presence of Zn increases both the solidus and liquidus temperatures, thus also increasing the endothermic peak temperature.

[0019] In Patent Document 3, paragraph 0019, an In-Cu-Sb-Bi alloy that does not contain Sn is disclosed, and it is stated that the desired creep properties can be obtained, the fluidity when filling the alloy is increased, and the occurrence of voids and variations in strength can be suppressed. In other words, it is presumed that in the second and third compositions containing Sn, when an alloy with a high content of In and Bi contains Sn, a Sn oxide film is formed during melting, and the fluidity of the molten alloy decreases. Furthermore, it has been found that the second composition has a lower Vickers hardness due to the presence of Sn.

[0020] Furthermore, it was found that the fourth composition, which contains Cu, exhibited inferior Vickers hardness. This is presumed to be due to the precipitation of coarse compounds containing Cu.

[0021] Therefore, the inventors conducted a detailed study on an In-Bi-Sb alloy that does not contain Zn, Sn, and Cu. Specifically, based on the binary equilibrium phase diagram of the elements constituting this alloy, the inventors carefully examined the Bi and Sb content so that the endothermic peak temperature would be in the range of 85-90°C and the Vickers hardness would be improved.

[0022] As a result, it was found that the endothermic peak temperature is 85-90°C when the Bi and Sb content is within a predetermined range. However, it was also found that even for alloys with an endothermic peak temperature in this range, there are alloys with low Vickers hardness due to a low Sb content.

[0023] The inventors focused on the following points in order to improve the Vickers hardness of an In-Bi-Sb alloy with an endothermic peak temperature of 85-90°C: Sb exists as InSb, and it is thought that the precipitation of this compound contributes to the increase in Vickers hardness. InSb remains sufficiently present until the start of melting (the temperature at which fusible plugs and sprinkler heads operate). Therefore, it is presumed that the Vickers hardness is maintained up to a temperature slightly lower than the temperature at which fusible plugs and sprinkler heads operate. Considering the melting behavior of the alloy during such heating, the inventors examined the content of each constituent element in detail.

[0024] In order to improve the Vickers hardness, the inventor focused on increasing the precipitation amount of InSb, which is a hard compound, among the compounds containing Bi, Sb, and In. However, in the alloy with a high Sb content, although the Vickers hardness was improved, it was found that the endothermic peak temperature exceeded 90°C. Also, in the alloy with an increased Bi content to increase the precipitation amount of In2Bi, similarly, although the Vickers hardness was improved, it was found that the endothermic peak temperature exceeded 90°C.

[0025] Thus, when obtaining an alloy with an endothermic peak temperature of 85 - 90°C, it was found that adjusting the endothermic peak temperature to this temperature range and exhibiting a high Vickers hardness showed a contradictory tendency. Therefore, as a result of further detailed studies by the inventors, it was found that an alloy with an endothermic peak temperature of 85 - 90°C and a high Vickers hardness can be obtained within an extremely narrow range of the contents of Bi and Sb, and the present invention was completed. Along with this, it was also found that a thrombolytic agent with an operating temperature of 85 - 90°C and a sprinkler head with an operating temperature of 85 - 90°C can be obtained. The present invention obtained based on these findings is as follows.

[0026] (0) An alloy characterized by consisting of, in mass%, Bi: 47.0 - 49.0%, Sb: 0.8 - 1.2%, and the balance being In. (1) An alloy characterized by having an alloy composition consisting of, in mass%, Bi: 47.0 - 49.0%, Sb: 0.8 - 1.2%, and the balance being In.

[0027] (2) A thrombolytic agent comprising the alloy according to (0) or (1) above, and characterized by having an operating temperature of 85 - 90°C.

[0028] (3) A sprinkler head comprising the alloy according to (0) or (1) above as a soluble alloy, and characterized by having an operating temperature of 85 - 90°C.

Brief Description of the Drawings

[0029] [Figure 1] Figure 1 shows an example of a fusible plug according to this embodiment, where Figure 1(a) is a top view and Figure 1(b) is a cross-sectional view AA of Figure 1(a). [Figure 2] Figure 2 shows a ternary diagram of the alloy according to this embodiment. [Modes for carrying out the invention]

[0030] The present invention will be described in more detail below. In this specification, "%" in relation to alloy composition refers to "mass%" unless otherwise specified.

[0031] 1. Alloy (1) Bi: 47.0~49.0% Bi controls the endothermic peak temperature obtained from the DSC curve and contributes to an increase in Vickers hardness. Bi can improve Vickers hardness through the precipitation of In2Bi. Furthermore, the endothermic peak temperature can be controlled by the amount of In2Bi precipitated and the timing of melting during alloy melting. If the Bi content exceeds 49.0%, the amount of In2Bi precipitated is too large, causing the endothermic peak temperature to exceed 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.

[0032] 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 inferior Vickers hardness. The lower limit of the Bi content is 47.0% or more, preferably 47.5% or more. The preferred range for Bi is 47.0–48.0%.

[0033] (2) Sb: 0.8~1.2% Similar to Bi, Sb controls the endothermic peak temperature obtained from the DSC curve and contributes to an increase in Vickers hardness. Sb can improve Vickers hardness through the precipitation of InSb. Furthermore, InSb remains sufficiently present until the start of melting (the temperature at which fusible plugs and sprinkler heads (hereinafter referred to as "fusible plugs, etc.") activate). Therefore, it can maintain Vickers hardness down to a temperature slightly lower than the activation temperature of fusible plugs, etc. In addition, the endothermic peak temperature can be controlled by the amount of Sb precipitated and the timing of melting during alloy melting.

[0034] If the Sb content exceeds 1.2%, the amount of InSb precipitated is large, causing the endothermic peak temperature to 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.

[0035] On the other hand, if the Sb content is less than 0.8%, InSb precipitation strengthening does not occur, and the Vickers hardness is inferior. The lower limit of the Sb content is 0.8% or more, preferably 0.9% or more. The preferred range for Sb is 0.9–1.1%.

[0036] (3) Remainder: In The remainder of the alloy according to the present invention is In. In addition to the elements mentioned above, it may also contain unavoidable impurities. The remainder of the alloy according to the present invention may consist of In and unavoidable impurities. Even if unavoidable impurities are present, it will not affect the effects described above. Furthermore, even if the elements described below are present as unavoidable impurities, it will not affect the effects described above.

[0037] Furthermore, the alloy according to the present 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 increases the operating temperature.

[0038] (3) Equations (1) to (2) 40.0 ≤ Bi / Sb ≤ 59.5 (1) 322 ≤ (Bi + Sb) × Vickers hardness ≤ 352 (2) In equations (1) and (2) above, Bi and Sb each represent the content as mass percent of the alloy composition.

[0039] The elements constituting the alloy according to the present invention preferably have an operating temperature of 85-90°C when used in fusible plugs and the like, and a Vickers hardness of 6.7 Hv or higher. These characteristics depend on the Bi and Sb elements that constitute the alloy according to the present invention.

[0040] When the Vickers hardness of the alloy according to the present invention satisfies equation (1), the amount of precipitated In2Bi and InSb is appropriate, and a high Vickers hardness of 6.7 Hv or higher can be obtained. Furthermore, since the operating temperature of the alloy according to the present invention is 85 to 90°C, which is a relatively low temperature range, it is not necessary to make the Vickers hardness unnecessarily high. Within a predetermined operating temperature range, if the balance between the total amount of elements contributing to the Vickers hardness and the Vickers hardness satisfies equation (2), it is considered to be an even more desirable alloy for use in fusible plugs and the like in the above operating temperature range.

[0041] 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. A more preferred range for formula (1) is 40.0 to 53.3, and particularly preferably 47.0 to 48.0. The above upper and lower limits can each define a further preferred range for formula (1).

[0042] The upper limit of equation (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 equation (2) is preferably 322 or more, more preferably 323 or more, and even more preferably 324 or more. A more preferred range for equation (2) is 323 to 346, and particularly preferably 324 to 330. The above upper and lower limits can each define a further preferred range for equation (2).

[0043] The measured values ​​of the alloy composition shown in Table 1 below were used for the calculations in equations (1) and (2). For the values ​​calculated from 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 and is intended to be used similarly in calculations for further alloys described in other literature, as all alloys must be treated in the same way.

[0044] 2. Fusible plug The fusible plug according to the present invention is formed by melting the alloy according to the present invention into a blank provided in the center of a blank material and sealing it. Depending on the shape of the blank material, various forms of fusible plugs are included, such as single-threaded type, double-threaded type, flared pipe type, and porous type.

[0045] The fusible plug according to the present invention has an operating temperature of 85 to 90°C. Within this temperature range, R448A refrigerant can be used. If the operating temperature is 90°C or lower, excessive internal pressure increases can be prevented, and internal pressure can be safely released. Furthermore, if the operating temperature is 85°C or higher, malfunction of the fusible plug can be prevented.

[0046] 3. Sprinkler heads The sprinkler head according to the present invention is equipped with the alloy according to the present invention as a fusible alloy, and its operating temperature is 85 to 90°C. The sprinkler head is installed on the ceiling of a building, etc., and is activated by the heat of a fire, spraying water to extinguish the fire. When the sprinkler head reaches its operating temperature due to a fire or the like, the fusible alloy constituting the heat-sensitive operating part of the sprinkler head melts, the valve opens and water is sprayed. One example of a sprinkler head is a flush-type sprinkler head. [Examples]

[0047] The present invention will be described with reference to the following embodiments, but the present invention is not limited to these embodiments. To demonstrate the effectiveness of the present invention, the following were evaluated using the alloys listed in Table 1: (1) solidus temperature, peak temperature, and liquidus temperature, (2) operating temperature, and (3) Vickers hardness.

[0048] (1) Solidus temperature, peak temperature, and liquidus temperature For alloys with the alloy compositions shown in Table 1, their respective temperatures were determined from DSC curves. The DSC curves were obtained using a Seiko Instruments DSC (model: Q2000) by heating at 5°C / min in air. The liquidus temperature was determined from the obtained DSC curves. The solidus temperature was also evaluated from the DSC curves. Furthermore, the peak temperature was determined from the largest endothermic peak in the obtained DSC curves.

[0049] (2) Operating temperature Using a single-threaded blank material 1 shown in Figure 1, a fusible plug was fabricated by filling the blank in the center of the blank material 1 with molten alloys having the alloy compositions shown in Table 1, and sealing it by cooling. This fusible plug was attached to a compressor via the threaded portion 3, and a pressure of 3 MPa was applied. Next, the fusible plug connected to the compressor was placed in a water tank, and the water in the tank was heated. The temperature at which air rapidly escaped from the fusible plug in the water tank was measured as the operating temperature. If the operating temperature was in the range of 85 to 90°C, it was determined that the desired operating temperature had been obtained.

[0050] (3) Vickers hardness A sample of solder alloy having the alloy composition shown in Table 1 was used, processed into a cylindrical shape of φ8mm × 12mm. This sample was tested using a micro-Vickers hardness tester (HM-100 (Mitutoyo Corporation)) at room temperature under the conditions of a load of 25g and an application time of 30 seconds. Ten arbitrary points were measured, and the average value was taken as the Vickers hardness. A value of 6.6Hv or higher was considered to have achieved the desired Vickers hardness. The results are shown in Table 1.

[0051] [Table 1]

[0052] As is clear from Table 1, all of Examples 1 to 9 had an operating temperature of 85 to 90°C and a Vickers hardness of 6.6 Hv or higher. Figure 2 shows a ternary diagram of the alloy according to this embodiment. Figure 2 illustrates Examples 1 to 9 and Comparative Examples 1 to 4, where ● represents an example and ○ represents a comparative example. Within the gray range 10 in Figure 2, alloys were obtained with an endothermic peak temperature of 85 to 90°C and a Vickers hardness of 6.6 Hv or higher.

[0053] On the other hand, Comparative Example 1 had a low Bi content, resulting in an operating temperature below 85°C and inferior Vickers hardness. Comparative Example 2 had a high Bi content, resulting in an operating temperature exceeding 90°C. Comparative Example 3 had a low Sb content, resulting in inferior Vickers hardness. Comparative Example 4 had a high Sb content, resulting in an operating temperature exceeding 90°C. Comparative Example 5 had a low Bi content, resulting in an operating temperature significantly below 85°C, and also had a high In content, resulting in inferior Vickers hardness.

[0054] Comparative Example 6 had low levels of Bi and Sb, and contained Cu, resulting in an operating temperature below 85°C and inferior Vickers hardness. Comparative Example 7 contained Zn, resulting in an operating temperature above 90°C. Comparative Examples 8 and 9 had low levels of Bi, and contained Sn, resulting in an operating temperature below 85°C and inferior Vickers hardness. [Industrial applicability]

[0055] The alloy according to the present invention can be used not only as a fusible plug for protective devices in refrigeration systems, but also as an alloy for sprinkler heads, which are also constantly subjected to pressure. Specifically, the alloy according to the present invention can be used as a fusible alloy component of a heat-sensitive operating part incorporated into a sprinkler head. [Explanation of Symbols]

[0056] 1. Blank material, 2. Alloy, 3. Screw part, 10. Range

Claims

1. An alloy characterized by having an alloy composition consisting of Bi: 47.0-49.0% by mass, Sb: 0.8-1.2%, and the remainder being In.

2. A fusible plug comprising the alloy described in claim 1, characterized in that its operating temperature is 85 to 90°C.

3. A sprinkler head characterized by comprising the alloy described in claim 1 as a fusible alloy and having an operating temperature of 85 to 90°C.

Images