JP2013167011A - Copper-based alloy for casting and instrument for water supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-based alloy for casting capable of exerting erosion-corrosion resistance and dezincification corrosion resistance.SOLUTION: This copper-based alloy contains copper, zinc, tin, aluminum and lead, wherein the tin content is 1.0-2.0 mass%, the aluminum content is 0.7-2.0 mass%, and the zinc equivalent is 35.0-44.0 mass%, and further contains antimony of 0.01-0.1 mass%, lead of 1.8-2.2 mass%, phosphorus of 0.01-0.1 mass%, and iron of less than 0.1 mass%. At least one of silicon and bismuth is substantially 0 mass%.

Description

  The present invention relates to a copper base alloy for casting and a water supply device using the alloy.

  Water supply appliances such as faucet fittings and water pipes include many large products with complicated internal shapes due to functional requirements such as securing water passages and temperature control. In the case of a product having such a complicated shape, casting is generally used because it can be efficiently manufactured. As the casting material, JISCAC203, Patent Documents 1 and 2 are used for the brass alloy, and JISCAC406 is used for the bronze alloy.

  A brass alloy has the merit that it can be cast using a simple mold in a production facility, but the occurrence of erosion and dezincification corrosion becomes a problem. Here, erosion refers to corrosion in which the alloy is scraped by the flow of water or the like, and dezincification corrosion refers to corrosion in which zinc in the alloy components is lost. Patent documents 1 and 2 etc. have developed materials that are satisfactory to some extent with respect to dezincing corrosion resistance, but their use is limited to products that do not lead to malfunction even if erosion occurs due to insufficient corrosion resistance. Has been.

  On the other hand, bronze alloys have high corrosion resistance and dezincification resistance, but a lot of patina is generated. When the patina is peeled off, the small holes in the functional part may be clogged, resulting in malfunction. In addition, bronze-based alloys are difficult to cast using a mold, and can be produced only by casting using a sand mold that is large in size and easily generates dust and noise.

JP-A-8-337831 JP 2009-263787 A

  If brass alloy can satisfy the two performances of erosion resistance and dezincification corrosion required for water supply equipment, it can prevent malfunction due to clogging of patina generated in bronze alloy and simple equipment. A wide range of products can be produced. For this reason, a brass-based copper-based alloy for casting that can exhibit erosion resistance and dezincification resistance is desired.

  This invention is made | formed in view of the said conventional situation, Comprising: It is set as the problem which should be solved to provide the copper base alloy for casting which can exhibit crushed corrosion resistance and dezincification corrosion resistance. Moreover, this invention also makes it the subject which should solve the provision of the water supply appliance which exhibits the said performance by casting.

  The copper-based alloy for casting of the present invention is a copper-based alloy for casting containing copper, zinc, tin, aluminum, and lead, and tin is 1.0 to 2.0% by mass, and aluminum is 0.7 to 2. 0 mass% and zinc equivalent are 35.0-44.0 mass% (Claim 1).

  According to the test results of the inventors, the addition of tin and aluminum exhibits erosion resistance that is not found in conventional brass alloys. If tin is less than 1.0 mass%, corrosion resistance is not enough, and if tin exceeds 2.0 mass%, castability will be impaired. If the aluminum content is less than 0.7% by mass, the corrosion resistance is not sufficient, and if the aluminum content exceeds 2.0% by mass, adhesion of corrosion products presumed to be caused by excessive addition of aluminum occurs. Moreover, high dezincification corrosion resistance is exhibited by controlling the zinc equivalent to 35.0 to 44.0% by mass. When the zinc equivalent is 35.0% by mass or more, it has been confirmed that the castability is sufficient, and when the zinc equivalent exceeds 44.0% by mass, the dezincification corrosion resistance is lowered.

  Therefore, according to the copper base alloy for casting of the present invention, it is possible to exhibit erosion resistance and dezincification corrosion resistance.

  The copper base alloy for casting according to the present invention preferably contains 0.1% by mass or less of antimony. According to the test results of the inventors, antimony improves the dezincification corrosion resistance of the copper base alloy for casting. Even if antimony is contained in an amount exceeding 0.1% by mass, the action reaches a peak, so the upper limit is made 0.1% by mass. Antimony is more preferably 0.01 to 0.1% by mass (claim 2). When antimony is less than 0.01% by mass, the dezincification corrosion resistance is not sufficient.

  As shown in Table 1, the copper-based alloy for casting of the present invention has a lead content of 1.8 to 2.2 mass%, an antimony content of 0.01 to 0.1 mass%, and a phosphorus content of 0.01 to 0.1. It is preferable that mass%, iron is less than 0.1 mass%, and copper is the balance. The inventors have confirmed the effects of the present invention with a copper-based alloy for casting that satisfies these requirements. According to the test results of the inventors, lead improves the machinability of the copper base alloy for casting. If lead is less than 1.8% by mass, the machinability is not sufficient, and if lead exceeds 2.2% by mass, the tensile strength and elongation are reduced. Antimony improves the dezincification resistance of casting copper-base alloys. Phosphorus improves the dezincification corrosion resistance of casting copper-base alloys. When phosphorus exceeds 0.1 mass%, tensile strength will fall. It is more preferable that phosphorus is 0.01 to 0.1% by mass. When phosphorus is less than 0.01% by mass, the dezincification corrosion resistance is not sufficient. Iron is an inevitable impurity. If iron is less than 0.1% by mass, the properties of the copper-based alloy for casting are hardly affected.

  In the copper base alloy for casting of the present invention, it is preferable that at least one of silicon and bismuth is substantially 0% by mass. This is because they tend to hinder recycling of the copper base alloy for casting. Here, substantially 0 mass% means less than 0.1 mass%.

  More preferably, the copper-based alloy for casting of the present invention has a zinc equivalent of less than 40.0% by mass (Claim 5). If the zinc equivalent is less than 40.0% by mass, the copper-based alloy for casting according to the present invention exhibits better dezincification corrosion resistance.

  More preferably, the copper-based alloy for casting of the present invention has a zinc equivalent of 38.0% by mass or more. When the zinc equivalent is 38.0% by mass or more, the copper-based alloy for casting of the present invention exhibits better castability.

  The water supply device of the present invention is characterized by comprising the above-described copper-based alloy for casting. This water supply device is manufactured by casting. And according to this water supply apparatus, it can have erosion corrosion resistance and dezincification corrosion resistance which were difficult conventionally.

It is a schematic cross section of a water stop part. It is a graph which shows the result of an erosion resistance evaluation test. It is a photograph which shows the surface of the comparative example 10 after an erosion resistance evaluation test. It is a photograph which shows the surface of the comparative example 6 after an erosion resistance evaluation test. It is a photograph which shows the surface of the comparative example 7 after an erosion resistance evaluation test. It is a photograph which shows the surface of Example 18 after an erosion resistance evaluation test. It is a photograph which shows the surface of Example 4 after an erosion resistance evaluation test. It is a photograph which shows the surface of Example 7 after a corrosion resistance evaluation test. It is a photograph which shows the surface of Example 19 after an erosion resistance evaluation test. It is a photograph which shows the surface of Example 1 after a corrosion resistance evaluation test. It is a photograph which shows the surface of the comparative example 17 after an erosion resistance evaluation test. It is a photograph which shows the surface of the comparative example 1 after an erosion resistance evaluation test. It is a cross-sectional photograph of Comparative Example 7 after the dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 18 after the dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 19 after a dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Comparative Example 17 after the dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 1 after a dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 4 after a dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 7 after a dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Example 15 after a dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Comparative Example 6 after the dezincification corrosion resistance evaluation test. It is a cross-sectional photograph of Comparative Example 10 after the dezincification corrosion resistance evaluation test. It is a top view of the metal mold | die for a both-ends restraint test used for castability evaluation. It is an external view of the faucet fitting made as a prototype by casting. It is process drawing which shows the manufacturing method of a faucet metal fitting. According to Example 18 after the actual use equivalent test, FIG. (A) is a cross-sectional photograph of the sheet, and FIG. (B) is a cross-sectional photograph of the screw. According to Example 19 after the actual use equivalent test, FIG. (A) is a cross-sectional photograph of the sheet, and FIG. (B) is a cross-sectional photograph of the screw. According to Comparative Example 17 after the actual use equivalent test, FIG. (A) is a cross-sectional photograph of the sheet, and FIG. (B) is a cross-sectional photograph of the screw. According to Comparative Example 7 after the actual use equivalent test, FIG. (A) is a cross-sectional photograph of the sheet, and FIG. (B) is a cross-sectional photograph of the screw. According to Comparative Example 10 after the actual use equivalent test, FIG. (A) is a cross-sectional photograph of a sheet, and FIG. (B) is a cross-sectional photograph of a screw.

  Hereinafter, the present invention will be described based on tests.

  Ingots made of the alloys of Examples 1 to 19 and Comparative Examples 1 to 18 whose components are shown in Tables 2 and 3 were prepared.

(Corrosion resistance evaluation test)
A sample simulating a water stop portion of a faucet fitting was manufactured by cutting from each ingot. The diameter of each sample is 9 mm, and the sheet around the diameter is 1 mm in the radial direction. The mechanism of the water stop part is shown in FIG. As shown in FIG. 1, a water stop plate 2 is provided above each sample 1. The test solution 3 that has passed through the interior of each sample 1 is folded back by the water stop plate 2 and comes into contact with each sample 1.

10L of 1% CuCl ₂ aqueous solution is used as a test solution. A food quality evaluation test was conducted. The test time was 2 hours and the pressure was adjusted every 30 minutes.

  The relationship between weight loss (g) and time (hr) of each sample was determined. FIG. 2 shows the results of Examples 1, 4, 7, 18, and 19 and Comparative Examples 1, 6, 7, 10, and 17 from each sample. Moreover, the photograph of the surface after the test of the said Example and a comparative example is shown to FIGS.

  As shown in FIGS. 2 and 3 to 12, the corrosion resistance of the alloy is improved by the addition of tin and aluminum. However, it is generally known that when only the amount of tin is increased, cracks occur during casting, and the machinability deteriorates. For this reason, tin is added within a range that does not adversely affect other performances, and in addition to that, aluminum is added, and the corrosion resistance is higher than when only tin is added without impairing other performances. Got to let. This is considered due to the formation of a strong oxide film on the surface of the alloy.

(Dezincification corrosion resistance evaluation test)
Using each ingot, a dezincification corrosion resistance evaluation test was performed based on JBMAT303.

  As a result, the dezincification depth was 47 μm in Comparative Example 7, 151 μm in Example 15, 127 μm in Example 16, 176 μm in Comparative Example 17, 42 μm in Example 1, 40 μm in Example 4, and 54 μm in Example 7. Example 15 was 83 μm, Comparative Example 6 was 59 μm, and Comparative Example 10 was 187 μm. Moreover, the cross-sectional photograph of the said Example and comparative example after a test is shown to FIGS.

  From the results of the dezincification corrosion resistance evaluation test, it was confirmed that when the aluminum content was increased by setting the tin content to 1.5% by mass, the dezincification corrosion resistance tended to deteriorate. It turns out that it is difficult to achieve both corrosive properties. However, by reducing zinc and controlling the zinc equivalent to 40.0 mass% or less, deterioration of dezincification corrosion resistance due to an increase in the amount of aluminum can be suppressed, and both erosion resistance and dezincification corrosion resistance are compatible. Is possible.

(Castability evaluation)
Castability was evaluated by the arrow restraint test method. In this test method, a both-end restraint test mold shown in FIG. 21 was used. This metal mold has a rectangular central mold 11 provided at the center and a pair of rectangular constraining molds 12a and 12b provided at both ends. The central mold 11 and the constraining molds 12a and 12b are made of S45C. These are combined together and fixed to each other by a bolt (not shown) to form a mold.

  A square recess 13 is formed at the center of the central mold 11. Further, the central mold 11 is formed with a groove 14 that communicates with the recess 13 and extends in the width direction. The recess 13 and the groove 14 have the same depth. The recess 13 is filled with a heat insulating material 16 made of casting sand and wax except for a portion 15 communicating with the groove 14.

  The central mold 11 is formed with a groove 17 communicating with the groove 14 and the portion 15. The constraining dies 12a and 12b are formed with triangular recesses 18a and 18b communicating with the ends of the groove 14, the portion 15 and the groove 17, respectively. The depths of the grooves 17 and the recesses 18a and 18b are also the same as the recesses 13 and the grooves 14. A double arrow-shaped cavity is formed by the groove 14, the portion 15, the groove 17, and the recesses 18a and 18b.

  The molten metal 19 of Examples and Comparative Examples was poured into the mold cavity. In the process in which the molten metal 19 in the cavity is cooled and solidified, the recesses 18a and 18b are restrained, and a solidification contraction force is generated. The central portion of the molten metal 19 in the cavity is delayed by the heat insulating material 16 as compared with the recesses 18a and 18b and becomes a final solidified portion, and the solidification shrinkage force is concentrated. Castability was evaluated by the presence or absence and degree of cracking at the central portion.

In Example 4 and the like, no cracks occurred. In Examples 1 to 3, a slight crack occurred, but it did not reach both ends, and the water stop cock shown in FIG. 24 could be produced. Therefore, it was confirmed that when the zinc equivalent is 35.0% by mass or more, good castability is ensured, and when the zinc equivalent is 38.0% by mass or more, better castability is ensured.

(Equivalent use test)
For Examples 18 and 19, and Comparative Examples 7, 10, and 17, the faucet fitting shown in FIG. This faucet fitting was manufactured by the manufacturing method shown in FIG.

  In this manufacturing method, first, in step S1, materials were prepared so that each faucet fitting was a component of Table 2 or Table 3. Next, in step S2, molding was performed by casting. In step S3, the obtained molded product was cut, and in step S4, the product was completed. This faucet fitting has a water stop mechanism shown in FIG.

  The test water contains 3% NaCl, has a pH of 6.5 to 6.6, and a temperature of 50 ° C. The flow rate is 2500 ml / min and the test period is 12 weeks. This test corresponds to an actual use of about 20-30 years. The cross-sectional photograph of the sheet | seat of Example 18, 19 and Comparative Example 7, 10, 17 and the cross-sectional photograph of a screw are shown to FIGS.

  26 to 30, it can be seen that dezincification corrosion does not occur even when the zinc equivalent is 40.0% by mass or more, and dezincification corrosion occurs when the zinc equivalent exceeds 44.0% by mass. That is, it can be seen that in a practical use scene, if the zinc equivalent is 44.0% by mass or less, the copper-based alloy for casting exhibits high dezincification corrosion resistance.

  For all of the examples and comparative examples, the erosion resistance evaluation test, the dezincification corrosion resistance evaluation test, and the castability evaluation were performed in the same manner. In the above erosion resistance evaluation test, it was found by the inventors' experiments that if the weight loss after the test is about 0.4 g or less, it is estimated that erosion does not occur in the actual use environment. ing. Therefore, the erosion resistance was evaluated as ◯ when the weight loss after the test was 0.4 g or less, and x when the weight loss was larger than 0.4 g. The anti-dezincing corrosion resistance is ○ if it corresponds to one or two types in the evaluation of dezincification corrosion susceptibility in JBMAT303, but it does not correspond to one or two types, but dezincification corrosion is seen in an actual use equivalent test. The case where there was no △ was marked as △, and the case other than ○ and △ was marked as x. Castability was evaluated as “◯” when there was no crack in the arrow constraint test method, “△” when there was a slight crack but not both ends, and “×” when both ends were cracked. If it is (circle) and (triangle | delta), the faucet metal fitting shown in FIG. 24 can be produced and it can be judged that it is the castability which can be practically used. The results in all Examples and Comparative Examples are shown in Table 4 and Table 5.

  Therefore, it contains copper, zinc, tin, aluminum and lead, tin is 1.0 to 2.0 mass%, aluminum is 0.7 to 2.0 mass%, and zinc equivalent is 35.0 to 44.0 mass%. The casting copper-based alloy can be molded by casting while having crushed corrosion resistance and high dezincification corrosion resistance that are not found in conventional brass alloys.

  If at least one of silicon and bismuth is substantially 0% by mass, recycling can be easily promoted.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments and can be appropriately modified and applied without departing from the spirit thereof.

  The present invention can be used for water supply equipment such as a faucet fitting.

Claims (7)

A copper-based alloy for casting containing copper, zinc, tin, aluminum and lead,
A copper-based alloy for casting, wherein tin is 1.0 to 2.0 mass%, aluminum is 0.7 to 2.0 mass%, and zinc equivalent is 35.0 to 44.0 mass%.   The copper-based alloy for casting according to claim 1, wherein the antimony is 0.01 to 0.1% by mass.   Lead is 1.8 to 2.2 mass%, antimony is 0.01 to 0.1 mass%, phosphorus is 0.01 to 0.1 mass%, iron is less than 0.1 mass%, and copper is the balance. The copper base alloy for casting according to claim 1 or 2.   The copper-based alloy for casting according to any one of claims 1 to 3, wherein at least one of silicon and bismuth is substantially 0% by mass.   The copper-based alloy for casting according to any one of claims 1 to 4, wherein a zinc equivalent is less than 40.0 mass%.   The copper base alloy for casting according to any one of claims 1 to 5, wherein a zinc equivalent is 38.0% by mass or more.   An appliance for water supply comprising the copper-based alloy for casting according to any one of claims 1 to 6.

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