Alloy, thrombolytic, and sprinkler head

Abstract

Provided are an alloy having an endothermic peak temperature obtained from a DSC curve of 85 to 90°C and having a high Vickers hardness, a thrombolytic agent having an operating temperature of 85 to 90°C, and a sprinkler head having an operating temperature of 85 to 90°C. **Solution**: The alloy has an alloy composition consisting of, by mass%, 47.0 to 49.0% Bi, 0.8 to 1.2% Sb, and the balance being In. Further, the thrombolytic agent and the sprinkler head include this alloy and have an operating temperature of 85 to 90°C.

Description

Technical Field

[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 coefficient are used. When the refrigerant is used in a refrigeration device, since the refrigerant is condensed, the pressure rises and the temperature also rises according to Boyle's law. And the rising temperature varies depending on the type of refrigerant. For this reason, 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 the HFC - based refrigerant, since the condensation pressure is 2.11 MPa, the critical temperature of R407C is 85.6 °C. For this reason, a fusible plug with an operating temperature range of about 90 - 95 °C is applied. Furthermore, when R410a of the 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 the dissolvable thrombolytics with various operating temperature ranges. For example, Patent Document 1 discloses a Zn-Bi-In alloy used for dissolvable thrombolytics that operate at 70 to 75°C and 95 to 100°C. In the same document, Sb is disclosed as an optional element to improve the creep properties.

[0007] Patent Document 2 discloses a Bi-Sb(-Sn)-In solder alloy with a melting temperature of 72 ± 2°C. In the same document, it is also disclosed that Sb improves the creep properties. Patent Document 3 discloses an In-Cu-Sb-Bi alloy that operates at 69 to 75°C. The alloy described in the same document shall not contain Sn, and like Patent Documents 1 and 2, improvement of creep properties has been studied.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] In Patent Document 1, R407C is used as a refrigerant with a small ozone depletion potential, and an alloy with an operating temperature of 90 to 95°C is used. However, HFC-based refrigerants containing R407C have the drawback of a high global warming potential (GWP). For this reason, in the 2016 Kigali Amendment to the Montreal Protocol, a stage target of reducing HFC-based refrigerants by 85% in terms of CO2 equivalent by 2036 has been set.

[0010] As a phased target, in Japan's fluorocarbon emission control law, in refrigerators and the like that use R407C, it is planned to replace the refrigerant with a refrigerant having a GWP of 1500 or less by 2025. However, the GWP of R407C is 1770, and this phased target cannot be achieved. R410a, an HCFC-based refrigerant, is assumed to be used in Patent Document 2 and Patent Document 3 due to its critical temperature. However, the GWP of this refrigerant is 2090, and like R407C, this phased target cannot be achieved.

[0011] Therefore, as an alternative refrigerant, R448A can be mentioned. The GWP of this refrigerant is 1380, and the target GWP value by 2025 can be achieved. 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 the thrombolytic agent to operate properly, the difference in critical temperature of 2°C is extremely large. If the operating temperature is set to 90 - 95°C using R448A, it may cause malfunction. Also, if the operating temperature of R448A is set in this temperature range, the internal pressure will increase, and the alloy used for the thrombolytic agent may not be able to withstand the internal pressure.

[0013] Thus, in order to obtain a thrombolytic agent applicable to R448A, which has a small ozone depletion potential and a small GWP, an alloy with an operating temperature of 85 - 90°C is required. And in order for the operating temperature to be in this temperature range, in the heat history obtained by differential scanning calorimetry (hereinafter referred to as the "DSC curve"), an alloy with an endothermic peak at 85 - 90°C is required.

[0014] However, in the inventions described in Patent Documents 1 - 3, the mechanical properties at this temperature range of the operating temperature have not been evaluated. Also, in these documents, the creep properties have been evaluated assuming a situation where the internal pressure is maintained high for a long time. Certainly, considering the condensation pressure of the refrigerant, it is reasonable to evaluate the creep properties.

[0015] However, with the recent global warming, the rapid freezing performance of refrigeration devices has been increasingly demanded. Along with this, since the acceleration of the condensation pressure rises rapidly, in addition to the creep characteristics, a high hardness of the alloy is also required. Furthermore, even when used for a sprinkler head, an improvement in the hardness of the soluble alloy is demanded. Thus, in view of the aforementioned stage goals for suppressing recent global warming, refrigeration devices, and the actual situation of sprinkler heads, it is urgent to provide an alloy having a predetermined operating temperature range and high hardness.

[0016] Therefore, an object of the present invention is to provide an alloy having an endothermic peak temperature obtained from a DSC curve of 85 to 90°C and a high Vickers hardness, a soluble thrombolytic agent having an operating temperature of 85 to 90°C, and a sprinkler head having an operating temperature of 85 to 90°C.

Means for Solving the Problems

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

[0018] These alloys each contain Zn, Sn, and Cu. Regarding the first composition, a finding was obtained that the endothermic peak temperature increases because it contains Zn. This is presumably because both the solidus temperature and the liquidus temperature increase due to the inclusion of Zn, and thus the endothermic peak temperature also increases.

[0019] The Sn-free In-Cu-Sb-Bi alloy disclosed in paragraph 0019 of Patent Document 3 is described as having desired creep properties, high fluidity when filling the alloy, and being able to suppress the generation of voids and variations in strength. That is, in the second and third compositions containing Sn, it is presumed that when an alloy with a high content of In and Bi contains Sn, a Sn oxide film is formed during melting, resulting in a decrease in the fluidity of the molten alloy. Furthermore, it was also found that the second composition has a low Vickers hardness because it contains Sn.

[0020] Also, for the fourth composition, since it contains Cu, it was found that the Vickers hardness is inferior. This is presumably because coarse compounds containing Cu precipitated.

[0021] Therefore, the present inventors have examined in detail an In-Bi-Sb alloy that does not contain Zn, Sn, and Cu. Specifically, based on the binary equilibrium phase diagrams of the elements constituting this alloy, the contents of Bi and Sb were examined in detail so that the endothermic peak temperature would be in the range of 85 to 90 °C and the Vickers hardness would be improved.

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

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

[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 alloys with a high Sb content, although the Vickers hardness was improved, it was found that the endothermic peak temperature exceeded 90°C. Also, in alloys 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 showing a high Vickers hardness are contrary tendencies. 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 when the contents of Bi and Sb are within an extremely narrow range, 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, by 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, by mass%, Bi: 47.0 - 49.0%, Sb: 0.8 - 1.2%, and the balance being In.

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

[0028] (3) A sprinkler head comprising the alloy described in (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 2

Mode for Carrying Out the Invention

[0030] The present invention will be described in more detail below. In this specification, “%” regarding the alloy composition is “mass %” unless otherwise specified.

[0031] 1. Alloy (1) Bi: 47.0 to 49.0% Bi controls the endothermic peak temperature obtained from the DSC curve and contributes to an increase in Vickers hardness. Bi can improve the Vickers hardness by the precipitation of In2Bi. Further, Bi can control the endothermic peak temperature depending on the precipitation amount of In2Bi and the timing of melting during melting of the alloy. When the content of Bi exceeds 49.0%, the precipitation amount of In2Bi is too large, so that the endothermic peak temperature exceeds 90°C. The upper limit of the content of Bi is 49.0% or less, preferably 48.5% or less, more preferably 48.0% or less.

[0032] On the other hand, when the content of Bi is less than 47.0%, the precipitation amount of In2Bi is small, so that the endothermic peak temperature is lower than 85°C and the Vickers hardness is inferior. The lower limit of the content of Bi is 47.0% or more, preferably 47.5% or more. The preferable range of Bi is 47.0 to 48.0%.

[0033] (2) Sb: 0.8 to 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 the Vickers hardness by the precipitation of InSb. Further, InSb sufficiently remains until the melting start point (the temperature at which the soluble thrombus and the sprinkler head “hereinafter, appropriately referred to as the “soluble thrombus etc.” operate). For this reason, it is possible to exhibit the function of maintaining the Vickers hardness up to a temperature slightly lower than the temperature at which the soluble thrombus etc. operates. Further, Sb can control the endothermic peak temperature according to the precipitation amount of Sb and the melting timing during melting of the alloy.

[0034] When the content of Sb exceeds 1.2%, the precipitation amount of InSb is large, so that the endothermic peak temperature exceeds 90°C. The upper limit of the content of Sb is 1.2% or less, preferably 1.1% or less, and more preferably 1.0% or less.

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

[0036] (3) Remainder: In The remainder of the alloy according to the present invention is In. In addition to the above-described elements, unavoidable impurities may be contained. The remainder of the alloy according to the present invention may consist of In and unavoidable impurities. Even when unavoidable impurities are contained, the above-described effects are not affected. Further, even if the elements described below are contained as unavoidable impurities, the above-described effects are not affected.

[0037] Note that the alloy according to the present invention does not contain Cu, Zn, and Sn. When Cu and Sn are contained, the operating temperature decreases and the Vickers hardness deteriorates. When Zn is contained, the operating temperature rises.

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

[0039] The elements constituting the alloy according to the present invention desirably have an operating temperature of 85 to 90°C and a Vickers hardness of 6.7 Hv or more when used in a thrombolytic agent or the like. These depend on Bi and Sb constituting the alloy according to the present invention.

[0040] When the Vickers hardness of the alloy according to the present invention satisfies formula (1), the precipitation amounts of In2Bi and InSb are appropriate, so that a high Vickers hardness of 6.7 Hv or more can be obtained. Further, since the alloy according to the present invention has an operating temperature of 85 to 90°C, which is a relatively low temperature range, it is not necessary to increase the Vickers hardness more than necessary. When the operating temperature is within a predetermined range and the balance between the total amount of elements attributable to the Vickers hardness and the Vickers hardness satisfies formula (2), it is considered to be a more desirable alloy for use in a thrombolytic agent or 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, still 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, still more preferably 47.0 or more, and even more preferably 47.5 or more. A more preferable range of 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 preferable range of formula (1).

[0042] (2) The upper limit of the formula is preferably 352 or less, more preferably 346 or less, still 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 the formula is preferably 322 or more, more preferably 323 or more, and still more preferably 324 or more. A more preferred range of the formula (2) is from 323 to 346, and particularly preferably from 324 to 330. The above upper and lower limits can respectively define further preferred ranges of the formula (2).

[0043] For the calculations of formula (1) and formula (2), the values shown in Table 1 below, which are the actually measured values of the alloy composition, were used. For the values calculated from formula (1) and formula (2), formula (1) is calculated to the first decimal place, and formula (2) is calculated as an integer value. This calculation rule is used in this application, and since all alloys must be treated in the same way, it is intended to be used in the same way for the calculations of further alloys described in other documents and the like.

[0044] 2. Thrombolytic The thrombolytic according to the present invention is obtained by melting and sealing the alloy according to the present invention in a blank provided at the center of a blank material. Various forms of thrombolytics are included, such as single-thread type, double-thread type, flare tube type, porous type, etc. according to the shape of the blank material.

[0045] The thrombolytic according to the present invention has an operating temperature of 85 - 90 °C. If the operating temperature is within this temperature range, the refrigerant R448A can be used. If the operating temperature is 90 °C or less, an excessive increase in internal pressure can be prevented, and the internal pressure can be safely released. Also, if the operating temperature is 85 °C or more, malfunction of the thrombolytic can be prevented.

[0046] 3. Sprinkler head The sprinkler head according to the present invention includes the alloy according to the present invention as a fusible alloy, and the operating temperature is 85 to 90°C. The sprinkler head is provided on the ceiling of a building or the like, operates due to the heat from a fire, and sprays water to extinguish the fire. When the operating temperature of the sprinkler head is reached due to a fire or the like, the fusible alloy constituting the heat-sensitive operating part provided in the sprinkler head melts, the valve is released, and water is scattered. As an example of the sprinkler head, a flush-type sprinkler head can be mentioned.

Example

[0047] The present invention will be described by the following examples, but the present invention is not limited to the following examples. To prove the effects of the present invention, using the alloys described in Table 1, (1) solidus temperature, peak temperature, and liquidus temperature, (2) operating temperature, and (3) Vickers hardness were evaluated.

[0048] (1) Solidus temperature, peak temperature, and liquidus temperature For the alloys having each alloy composition shown in Table 1, each temperature was determined from the DSC curve. The DSC curve was obtained by heating at 5°C / min in the atmosphere using a DSC (model number: Q2000) manufactured by Seiko Instruments Inc. The liquidus temperature was determined from the obtained DSC curve. Also, the solidus temperature was evaluated from the DSC curve. Further, in the obtained DSC curve, the largest endothermic peak was determined as the peak temperature.

[0049] (2) Operating temperature Using the single-screw type blank material 1 shown in FIG. 1, the blank provided at the center of the blank material 1 was filled with a molten alloy having each alloy composition shown in Table 1, and sealed by cooling to produce a fusible plug. This fusible plug was attached to a compressor via the screw portion 3, and a pressure of 3 MPa was applied. Next, the fusible plug connected to the compressor was put into a water tank, and the water in the water tank was heated. The temperature at which air suddenly 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 was obtained.

[0050] (3) Vickers hardness Samples of a solder alloy having the alloy composition shown in Table 1, processed into a cylindrical shape of φ8 mm × 12 mm, were used. Using a micro-Vickers hardness tester (HM-100 (manufactured by Mitutoyo Corporation)), at room temperature, 10 arbitrary points were measured under the conditions of a load of 25 g and an addition time of 30 seconds, and the average value was taken as the Vickers hardness. If it was 6.6 Hv or more, it was judged that the desired Vickers hardness was obtained. The results are shown in Table 1.

[0051]

Table 1

[0052] As is clear from Table 1, in Examples 1 to 9, the operating temperatures were all 85 to 90°C, and the Vickers hardness was 6.6 Hv or more. FIG. 2 shows the ternary diagram of the alloy according to this embodiment. In FIG. 2, Examples 1 to 9 and Comparative Examples 1 to 4 are shown. In the figure, ● represents an example, and 〇 represents a comparative example. Within the range 10 shown in gray in FIG. 2, an alloy with an endothermic peak temperature of 85 to 90°C and a Vickers hardness of 6.6 Hv or more was obtained.

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

[0054] In Comparative Example 6, since the contents of Bi and Sb were low and it contained Cu, the operating temperature was below 85°C, and the Vickers hardness was also inferior. In Comparative Example 7, since it contained Zn, the operating temperature exceeded 90°C. In Comparative Examples 8 and 9, since the content of Bi was low and it contained Sn, the operating temperature was below 85°C, and the Vickers hardness was also inferior.

Industrial Applicability

[0055] The alloy according to the present invention can be used not only as a fusible plug used in a protection device of a refrigeration apparatus but also as an alloy for a sprinkler head that is constantly under pressure. Specifically, the alloy according to the present invention can be used as a fusible alloy that is a component of a heat-sensitive operating part incorporated in a sprinkler head.

Explanation of Signs

[0056] 1 blank material, 2 alloy, 3 screw part, 10 range

Claims

1. An alloy having an alloy composition consisting of, in mass%, 47.0 to 49.0% Bi, 0.8 to 1.2% Sb, and the balance In, and having a Vickers hardness of 6.6 Hv or more.

2. A fusible plug comprising the alloy according to claim 1 and having an operating temperature of 85 to 90°C.

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

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