JP2009133004A - Copper-based alloy for casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper-based alloy for casting which exhibits excellent corrosion resistance and dezincification resistance and hardly causes casting cracks. <P>SOLUTION: The copper-based alloy for casting has a composition containing copper as a main component, 36.0±1.0 mass% zinc, 0.005-1.9 mass% germanium, and 0.045-0.135 mass% antimony. Furthermore, the allay is added with less than 0.05 mass% tin, 2.0±0.5 mass% lead, 0.11±0.1 mass% iron, 1.0±0.5 mass% nickel, 0.2-0.6 mass% aluminum, and 8-30 ppm boron. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a copper base alloy for casting.

  General casting brass, such as YBsC3 (CAC203), tin (Sn) is 1.0 mass% or less, lead (Pb) is 0.5 to 3.0 mass%, aluminum (Al) is 0.5 mass. % Or less, iron (Fe) is 0.8 mass% or less, copper (Cu) is 58.0 to 64.0 mass%, and zinc (Zn) is the balance. YBsC3 is used in products such as faucet fittings and water pipes such as water pipes from the viewpoints of castability and machinability.

  However, YBsC3 has a problem that dezincification corrosion occurs. According to the test results of the inventors, YBsC3 showed a dezincification depth of 198 μm in the JBMAT-303 test. Therefore, higher corrosion resistance is required for products made of currently general brass for casting. For this reason, the copper base alloy for casting in consideration of the corrosion resistance disclosed in Patent Documents 1 and 2 has been proposed.

  The copper-based alloy for casting disclosed in Patent Document 1 is 0.05 to 0.2% by mass of tin, 0.5 to 3.0% by mass of lead, 0.1 to 0.5% by mass of aluminum, antimony ( Any one or more of Sb), arsenic (As) or phosphorus (P) is 0.05 to 0.3% by mass, zinc is 33.0 to 37.0% by mass, and copper is the balance.

  Moreover, the copper-based alloy for casting disclosed in Patent Document 2 is 0.5 to 1.2% by mass of tin, 1.5 to 2.4% by mass of lead, 0.5 to 1.2% by mass of aluminum, Nickel (Ni) is 0.5 to 1.2% by mass, boron (B) is 4 to 12 ppm, copper is 60.0 to 65.0% by mass, and zinc (Zn) is the balance.

  These copper-based alloys for casting have higher corrosion resistance than general casting brass. For example, according to the test results of the inventors, the copper base alloy for casting of Patent Document 1 showed a dezincification depth of about 40 to 50 μm in the JBMAT-303 test.

Japanese Patent No. 3461081 JP-A-9-176762

  However, according to the test results of the inventors, antimony, tin and nickel are intentionally added to the copper base alloy for casting considering the above corrosion resistance in order to improve the corrosion resistance. Due to the influence of the additive element, the more complicated the product is, the easier it is to cause casting cracks when casting the product.

  In addition, the above-described copper-based alloy for casting considering the corrosion resistance has a dezincification depth of about 40 to 50 μm in the JBMAT-303 test, although the dezincification corrosion is improved as compared with general casting brass. This does not mean that dezincification corrosion does not occur.

  The present invention has been made in view of the above-described conventional situation, and solves the problem of providing a copper base alloy for casting that is less prone to casting cracking and that can exhibit better corrosion resistance including dezincing resistance. It is an issue that should be done.

  The inventors have conducted intensive research to solve the above-mentioned problems, and are generally known to have an effect of improving dezincing resistance in brass, such as antimony (Group 15-1 period) and arsenic (Group 15-1). (4 periods) and germanium (Ge) (Group 14-1 period 4), which is close in position on the periodic table, was tried. As a result, it was found that an improvement in dezincing resistance was confirmed by increasing the amount of germanium alone, and that the above problem could be solved by the coexistence of germanium and antimony. Thus, the inventors have completed the present invention.

  That is, the copper-based alloy for casting of the present invention is a copper-based alloy for casting containing copper as a main component and containing zinc, and further includes germanium and antimony.

  According to the test results of the inventors, the copper base alloy for casting to which germanium and antimony are added shows 3 to 6 μm in the JBMAT-303 test, which is more resistant to the conventional copper base alloy for casting considering the corrosion resistance. Dezincing property improved. This is considered to be a synergistic effect of germanium and antimony. Moreover, the solidification temperature range of the copper-based alloy for casting according to the present invention also decreased compared to the conventional copper-based alloy for casting considering the corrosion resistance.

  Therefore, according to the copper base alloy for casting of the present invention, it is difficult to cause casting cracks and can exhibit more excellent corrosion resistance including dezincing resistance.

  According to the test results of the inventors, the copper-based alloy for casting according to the present invention has 36.0 ± 1.0% by mass of zinc, 0.005% by mass or more of germanium, and 0.045 to 0.135 of antimony. It is preferable that it is mass%. The germanium content is more preferably 1.9% by mass or less. The inventors confirmed the above effects in these copper-based alloys for casting.

  According to the test results of the inventors, the copper-based alloy for casting according to the present invention has tin of less than 0.05% by mass, lead of 2.0 ± 0.5% by mass, and iron of 0.11 ± 0. 0.1% by mass, nickel is 1.0 ± 0.5% by mass, aluminum is 0.2-0.6% by mass, and boron is preferably 8-30 ppm. The inventors confirmed the above effects in these copper-based alloys for casting. Tin and nickel improve the corrosion resistance of the casting copper base alloy, lead improves the workability of the casting copper base alloy, boron refines the crystals of the casting copper base alloy, and aluminum improves the hot water flow.

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

  In order to investigate the effect of addition of germanium, a copper base alloy for casting to which germanium was added at a ratio shown in Table 1 was prepared, and samples of test products 1-1 to 1-5 were prepared using these copper base alloys for casting. Casted. Moreover, YBsC3 (CAC203) was used as comparative product 1. About each sample, the below-mentioned dezincing resistance test and cast cracking evaluation were performed.

  Moreover, in order to investigate the synergistic effect of germanium and antimony, a copper base alloy for casting to which germanium and antimony were added in the ratio shown in Table 2 was prepared, and test products 2-1 to 2 were prepared using these copper base alloys for casting. A sample of -9 was cast. Further, a copper base alloy for casting added at a ratio of Sb = 0.08% and Ge = 0% was set as Comparative Example 2. About each sample, the below-mentioned dezincing resistance test and cast cracking evaluation were performed.

(Dezincing resistance test)
JBMA T-303 test: Carbonate buffer solution (5 × 10 ⁻³ M NaHCO ₃ ) containing chloride (0.5 NaCl) was used as a test solution (60 ° C.), and CO ₂ + O ₂ + N ₂ (10:20). :)) In an environment saturated with a mixed gas of 70), each sample (area 100 to 200 mm ² ) embedded in the resin was supplied with an anode current of 1.0 mA / cm ² through a lead wire for 24 hours, and then the cross section was observed with a microscope. Observed, the depth (μm) of the dezincification layer was measured.

  The results are shown in Tables 3 and 4 and FIGS. 1 and 2 show the dezincing depth (μm) due to the change in the amount of germanium, and FIG. 2 shows a part of FIG. 1 in an enlarged manner. FIG. 3 shows the dezincing depth (μm) due to the change in the amount of antimony.

  As shown in Table 3 and FIG. 1, when antimony is not added, the dezincing depth is reduced from about 200 μm to about 40 μm with an increase in the amount of germanium up to 0.7 mass%. It can be seen that the dezincification property is improved. However, when germanium exceeds 0.7 mass%, the dezincing depth becomes substantially constant at about 40 μm, and no further improvement in dezincing resistance is observed.

  Moreover, as shown in Table 4 and FIG. 3, when no germanium was added, antimony was 0.08% by mass and the dezincification depth was about 40 μm. Sex is getting worse. That is, when only germanium and antimony are added alone, the dezincing resistance is improved only when the dezincing depth is about 40 μm.

  On the other hand, as shown in FIG. 2, when germanium is 0.02 to 0.1% by mass and antimony is 0.08% by mass, the dezincification depth becomes 3 to 6 μm, and the known corrosion resistance is taken into consideration. It can be seen that it is more dezincing resistant than copper-based alloys. In addition, when the amount of germanium is 0.02 to 0.1% by mass and the amount of antimony is 0.18% or 0.35%, an improvement in dezincing resistance by increasing the amount of germanium was observed.

  Therefore, a casting copper base alloy having a composition in which germanium is added in an amount of 0.02 to 0.1% by mass and antimony is added in an amount of 0.08% by mass has the best dezincing resistance. It can be seen that it exhibits dezincing resistance higher than that of the alloy.

(Casting cracking evaluation)
DSC analysis: For the test products 2-1 to 2-3 and the comparative product 2, samples were obtained from the component analysis samples and subjected to thermal analysis. Measurement conditions are a temperature rising rate of 20 ° C./min (700 ° C.) → 10 ° C./min (1030 ° C.) → 10 ° C./min (700 ° C.). The atmosphere was N ₂ and the standard sample and cell used were Al ₂ O ₃ . Table 5 shows the results of the solidification temperature range (° C). FIG. 4 shows the relationship between the amount of germanium and the solidification temperature width (° C.). When the solidification temperature range is wide, the growth of dendrite crystals tends to proceed, the crystals are entangled with each other, shrinkage stress is generated, and casting cracks are likely to occur.

  From this result, it can be seen that when germanium and antimony are added, the solidification temperature width decreases as the amount of germanium added increases. Further, the casting copper-based alloy to which germanium is added has a wider solidification temperature range than the comparative product 1 (YBsC3) which is a general casting brass. Compared to known copper-based alloys for casting considering corrosion resistance, the solidification temperature range is narrow. From this result, it is clear that the addition of germanium improves the cast cracking property over the known copper-based alloy for casting considering the corrosion resistance.

  The surface analysis results of the test product 2-3 are shown in FIGS. FIG. 5 shows the distribution of zinc in the copper-based alloy for casting, FIG. 6 shows the distribution of germanium in the copper-based alloy for casting, and FIG. 7 shows the distribution of antimony in the copper-based alloy for casting. Indicates the state. The measurement conditions are an acceleration voltage of 15.0 kV, an irradiation current of 4.996e-07A, a measurement region of 102 μm square, and a measurement time per point of 100 milliseconds. The portion with a lot of zinc in FIG. 5 is a β phase, and the portion with a small amount of zinc is an α phase. Compared to the α phase, the β phase is more susceptible to dezincification, and improving the corrosion resistance of the β phase leads to an improvement in the overall corrosion resistance.

  5-7, it turns out that germanium and antimony exist abundantly in the beta phase in the copper base alloy for casting, and coexist with zinc. From this, it is presumed that β-phase dezincification corrosion is prevented by the synergistic effect of germanium and antimony.

  Therefore, according to the copper base alloy for casting of this invention, it turns out that it is hard to produce a casting crack and can exhibit more superior corrosion resistance including dezincification resistance. Moreover, since this copper base alloy for casting is excellent in dezincing resistance, it turns out that the erosion which is a phenomenon eroded by water, such as a tap water, does not advance easily. For this reason, even if this copper-based alloy for casting constitutes a seal portion or the like of the faucet fitting, the faucet fitting can exhibit excellent durability. Further, this copper-based alloy for casting can constitute a faucet fitting with an integrated seal portion and the like.

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

It is a graph which shows the relationship between the amount of germanium and the dezincification depth. It is a graph which shows the relationship between the amount of germanium and the dezincification depth. It is a graph which shows the relationship between an antimony amount and a dezincification depth. It is a graph which shows the relationship between the amount of germanium and the solidification temperature range. It is a surface analysis result which shows the distribution state of zinc in the copper base alloy for casting. It is a surface analysis result which shows the distribution state of germanium in the copper base alloy for casting. It is a surface analysis result which shows the distribution state of antimony in the copper base alloy for casting.

Claims (5)

  A copper-based alloy for casting, which contains copper as a main component and contains zinc, and further contains germanium and antimony.   The copper-based alloy for casting according to claim 1, wherein zinc is 36.0 ± 1.0% by mass, germanium is 0.005% by mass or more, and antimony is 0.045 to 0.135% by mass.   The copper base alloy for casting according to claim 2, wherein germanium is 1.9% by mass or less.   Tin is less than 0.05% by mass, lead is 2.0 ± 0.5% by mass, iron is 0.11 ± 0.1% by mass, nickel is 1.0 ± 0.5% by mass, aluminum is 0.2% The copper-based alloy for casting according to claim 2 or 3, wherein -0.6 mass% and boron are 8-30 ppm.   The copper-based alloy for casting according to any one of claims 1 to 4, wherein germanium is 0.02 to 0.1% by mass and antimony is 0.08% by mass.