WO2012026490A1 - 銅合金のBi溶出防止方法 - Google Patents
銅合金のBi溶出防止方法 Download PDFInfo
- Publication number
- WO2012026490A1 WO2012026490A1 PCT/JP2011/069048 JP2011069048W WO2012026490A1 WO 2012026490 A1 WO2012026490 A1 WO 2012026490A1 JP 2011069048 W JP2011069048 W JP 2011069048W WO 2012026490 A1 WO2012026490 A1 WO 2012026490A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- copper alloy
- nitric acid
- elution
- mass
- shot blasting
- Prior art date
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/10—Etching compositions
- C23F1/14—Aqueous compositions
- C23F1/16—Acidic compositions
- C23F1/18—Acidic compositions for etching copper or alloys thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C3/00—Abrasive blasting machines or devices; Plants
- B24C3/32—Abrasive blasting machines or devices; Plants designed for abrasive blasting of particular work, e.g. the internal surfaces of cylinder blocks
- B24C3/322—Abrasive blasting machines or devices; Plants designed for abrasive blasting of particular work, e.g. the internal surfaces of cylinder blocks for electrical components
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B7/00—Water main or service pipe systems
- E03B7/006—Arrangements or methods for cleaning or refurbishing water conduits
Definitions
- the present invention relates to a method for preventing the elution of Bi (bismuth) contained in an alloy material, and in particular, to prevent the elution of Bi of a copper alloy for preventing the elution of Bi contained in a copper alloy of piping equipment such as valves and joints or strainers. On the way.
- Bi bismuth
- Patent Document 1 discloses a technology for removing lead from the water-contacting portion of a blue brass piping device, and more specifically, the surface-contacting portion of the piping device is surface-treated with nitric acid of 0.5 to 7 wt%. This makes it possible to significantly suppress the elution of lead into tap water.
- Patent Document 2 discloses a lead elution reduction treatment method in which a lead-containing copper alloy is immersed in a cleaning solution made of an alkaline etching solution to remove lead on the surface.
- Patent No. 3345569 Patent No. 3182765 gazette JP 2008-88526 A
- the lead elution prevention method of Patent Document 1 aims to prevent the elution of lead and is not directed to the elution prevention of Bi.
- the nitric acid concentration is low, the removal effect of Bi does not become high, and it is not suitable for using this technology as Bi elution prevention technology.
- Bi which is a noble metal element, can not be effectively removed by the alkaline cleaning solution.
- Patent Document 3 it is described that nitric acid similarly dissolves copper and Bi because copper and Bi have an extremely close potential (see the paragraph 0053), and the preferential removal of Bi is disclosed. Not.
- Table 3 of the same document 3 shows data to the effect that Bi is also removed, but this data is intended for sand castings. Since sand castings show surface segregation and many Bi are also present on the surface, data from specimens with polished surfaces are necessary to accurately grasp the removal of Cu and Bi from the alloy surface. Therefore, the same reference 3 remains in the technology of polishing the surface of the copper alloy regardless of the elements such as Cu and Bi. Furthermore, in a copper alloy containing Bi, if the content of lead is tightened in order to suppress the elution of lead, it is possible to melt and recycle the return material generated in the factory etc. and the scrap material recovered from the market. It becomes difficult, and the cost increase of the product can not be avoided.
- lead-free copper alloys that do not contain Bi are inferior in machinability, which makes it difficult to process products made of lead-free copper alloys in mass-production equipment for lead-containing copper alloys. is there.
- a lead-free copper alloy containing Si recycling is difficult, and specifically, 85-5-5-5 alloy used for piping equipment such as a valve, if Si is mixed, may cause a void
- the mechanical properties and the durability are significantly deteriorated due to the increase.
- the upper limit of Si content is 0.01 mass% in JIS standard and 0.005 mass% in ASTM standard, but in fact, 0.003 mass% contamination adversely affects mixing of Si from scraps, which becomes a major problem .
- a lead-free copper alloy which does not contain Bi another problem as a copper alloy arises, so it is desirable to contain Bi as a result.
- the present invention has been developed as a result of intensive studies, and the purpose of the present invention is from a leadless copper alloy piping apparatus etc. containing a small amount of lead and a predetermined amount of Bi.
- An object of the present invention is to provide a Bi elution preventing method for preventing Bi elution.
- the invention according to claim 1 is a matrix consisting of Cu, Zn, Sn, etc. with nitric acid having a concentration of 4 to 20 mass% for Bi present on the surface of a copper alloy containing at least Bi. It is a Bi elution preventing method in which Bi is preferentially dissolved and Bi is selectively removed while suppressing the dissolution.
- the invention according to claim 2 is the Bi elution preventing method in which the elution of Pb is also suppressed by setting the nitric acid concentration to 10 to 20 mass%.
- the surface of the copper alloy is subjected to shot blasting to remove corrosiveness such as oxides produced by nitric acid. It is a Bi elution prevention method capable of removing organisms and making the surface glossy.
- the invention according to claim 4 is the method according to claim 4, wherein the shot blasting is performed within the depth range of the void formed on the surface of the copper alloy by removing Bi with nitric acid, thereby suppressing the exposure of Bi present inside the copper alloy. It is the elution prevention method.
- the invention according to claim 5 is the elution of Bi in which the exposure of Bi present inward of the copper alloy is suppressed by shot blasting and closing the voids formed on the surface of the copper alloy by Bi removal with nitric acid. It is a prevention method.
- Bi is removed by nitric acid from the water-contacting part of a leadless copper alloy piping equipment containing Bi as a substitute for lead and containing a trace amount of lead and Bi.
- the elution of Bi can be prevented, and furthermore, the lead present in the water-contacting part can also be removed by this acid cleaning.
- Bi is removed by nitric acid from a piping device made of a leadless copper alloy containing Bi as a substitute for lead and containing a trace amount of lead and Bi by elution of Bi.
- a piping device made of a leadless copper alloy containing Bi as a substitute for lead and containing a trace amount of lead and Bi by elution of Bi.
- the limit of the shot blast for satisfying the elution standard of Bi can be set to optimum conditions, and by performing shot blasting under these conditions, the minimum depth of the metal surface can be shot while preventing Bi from eluting out from the metal surface after Bi removal. By blasting, it is possible to achieve gloss.
- the Bi elution prevention method of Bi containing copper alloy in this invention is demonstrated in detail based on embodiment.
- the first method of this Bi elution prevention method contains at least Bi, and for example, 4 to 20 mass of Bi present on the surface of a copper alloy valve or joint for water supply containing a trace amount of lead and Bi. While suppressing dissolution of Cu with 1% nitric acid, Bi is preferentially dissolved to remove Bi.
- the preferential dissolution and removal means that the elution ratio of Bi is higher than the dissolution ratio of the main element (for example, Cu) constituting the matrix of the copper alloy.
- the surface treatment time is preferably 5 minutes or more.
- 20 mass% nitric acid refers to nitric acid obtained by diluting 60 mass% concentrated nitric acid five times. Even if it is the same 20% nitric acid, there is also 20% nitric acid obtained by diluting 67% concentrated nitric acid 5 times as in Patent Document 3, but the nitric acid concentration in this embodiment is the same even with 20% nitric acid. It is different from the concentration.
- the control concentration for achieving the most suitable nitric acid concentration is when the nitric acid concentration is 15 to 20 mass% using 60 mass% concentrated nitric acid In this case, the nitric acid concentration of 22.3 to 30.2 wt% of Patent Document 3 does not overlap with the nitric acid concentration. Also, even if the range of nitric acid concentration in the same document 3 overlaps the range of nitric acid concentration in the Bi elution prevention method of the present invention, as described above, in the same document 3, Bi is treated preferentially over copper.
- the concentration range of nitric acid shown in the same document 1 is 0.6 to 8.0% nitric acid when converted to 60% nitric acid, so the concentration range of nitric acid in this embodiment is the same as that of the same document. It does not overlap with 1.
- the second method of the Bi elution prevention method is to remove the Bi present on the surface of the copper alloy containing at least Bi with nitric acid, and then shot blast the surface of the copper alloy to form oxides etc. It is intended to remove corrosive organisms and to make the surface bright.
- the voids formed on the surface of the copper alloy are closed by shot blasting, thereby suppressing the exposure of Bi present inside the copper alloy.
- Examples of equipment for performing shot blasting include an apron type, a hanger type, and a drum type, and an appropriate type among these is selected according to the composition of the material, the type of product, and the purpose of use, etc. do it.
- a material of the shot ball there are various materials such as steel, stainless steel, glass, sand and the like, for example, which can be appropriately selected and used from these. In that case, since a new amount of Bi is exposed on the surface of the work when the amount of grinding increases, in order to reduce the collision energy with the surface of the work, use a small diameter shot ball or obtain an effect of compressing without scraping the surface of the work. It is desirable to use a spherical shot ball as much as possible.
- the shot balls of the shot blast should preferably have a diameter of, for example, 0.1 to 0.6 mm, and more preferably 0.3 to 0.6 mm, whereby the discoloration due to oxide scale can be effectively removed.
- the average crystal grain size of the Bi phase dispersed and present in the alloy is R ( ⁇ m) and the Bi content is X (mass%), it is removed by polishing by shot blasting.
- the Bi elution can be suppressed by setting the thickness T 1 to 0.1 to 0.65 R / X ( ⁇ m) as the thickness T 1 of the alloy. At this time, it is possible to suppress the leaching amount of Bi from the copper alloy to less than 100 ppb.
- FIG. 1 the schematic diagram of the surface vicinity of the copper alloy which consists of CAC911 is represented, This CAC911 is comprised from the chemical component value of Table 1.
- FIG. 1 the schematic diagram of the surface vicinity of the copper alloy which consists of CAC911 is represented, This CAC911 is comprised from the chemical component value of Table 1.
- Bi is removed by nitric acid by making the maximum depth D max when scraping the alloy surface by shot blasting smaller than the depth t from the alloy surface after Bi is removed by nitric acid. After that, it is possible to prevent Bi from newly appearing on the surface of the copper alloy by shot blasting.
- a two-dot chain line indicates an imaginary line when the treatment with nitric acid is not performed.
- the crystal grain size of the Bi phase is R ( ⁇ m)
- the maximum corrosion depth by nitric acid is R ( ⁇ m) when the corrosion of the matrix is ignored. Therefore, when the polishing amount exceeds R ( ⁇ m), a new Bi phase is completely exposed on the alloy surface.
- the reference value of Bi elution amount in the NSF leaching test which is a standard for public health and safety, is 100 ppb, and in the case of a product after surface treatment with nitric acid (hereinafter referred to as surface treatment product), it is about 100 to 150 ppb. Therefore, if the elution amount is suppressed to about 50% (50 to 75 ppb), the reference value can be sufficiently satisfied. In other words, if the area ratio of Bi on the alloy surface is 50%, it is possible to satisfy the reference value, and for that purpose, it is sufficient to make the amount of polishing by shot blast less than R / 2.
- the Bi content of the alloy can be mentioned as a factor that affects the leaching amount of Bi. Since the Bi content and the Bi elution amount of the alloy are in a proportional relationship, the Bi elution amount of the alloy having a Bi content of X is based on CAC 911 having a Bi content of 1.3 (mass%). It will be X / 1.3 times. Therefore, the amount that can be polished by shot blasting is 1.3 / X times.
- the lower limit value of the amount of polishing may be the amount of polishing under shot blasting conditions in which discoloration can be removed. Since a shot time of at least 1 min is necessary in consideration of finishing unevenness in mass production, a polishing amount of 0.1 ⁇ m in a shot time of 1 min is set as the lower limit with a ⁇ 0.3 mm stainless steel shot. From the above, it is possible to clear the NSF leaching test by setting the thickness T 1 to be removed by polishing to 0.1 to 0.65 R / X ( ⁇ m) as described above, and to reduce the amount of Bi elution. It becomes possible to offer.
- the average crystal grain size of the Bi phase dispersed and present in the alloy is R ( ⁇ m), and the Bi content is Y
- the shot blasting conditions for suppressing the elution amount of Pb will be described in more detail.
- the Pb elution amount of the surface treatment product in the case of containing 0.47 (mass%) of Pb is about 50 ppb, and the standard value of Pb is 15 ppb, so it is necessary to make the Pb elution amount 15/50.
- Pb is alloyed with the Bi phase in the alloy, if it is assumed that the average grain size of the Pb phase is indicated, it is expressed similarly to the average grain size R of the Bi phase. For this reason, in order to suppress the exposure of Pb to 15/50, the polishing amount by shot blasting may be less than 15/50 ⁇ R.
- the elution amount of Pb is in proportion to the content thereof, therefore, based on CAC 911 having a Pb content of 0.47 (mass%), the Pb of the alloy having a Pb content of Y The elution amount is Y / 0.47 times, and the amount that can be polished by shot blasting is 0.47 / Y.
- the lower limit value of the polishing amount is set to the lower limit of 0.1 ⁇ m in the shot time of 1 min with a ⁇ 0.3 mm stainless steel shot, as in the case of the Bi elution prevention. From the above, the NSF leaching test can be cleared by setting the thickness T 2 removed by polishing to 0.1 to 0.141 R / Y ( ⁇ m) described above, and the Pb elution amount can be suppressed to less than 15 ppb. It will be possible to provide different products.
- T 3 0.1 to 0.047 R / Y ( ⁇ m)
- the amount of leaching of Pb from the copper alloy is lower. It can also be suppressed to less than 5 ppb.
- the treatment steps targeted by the present invention include a water washing step, a washing step and a drying step.
- the surface treatment of the copper alloy is performed in the order of the water washing step, the surface treatment step, the washing step, the drying step, and the shot blasting step.
- the Bi elution prevention method of the present invention may be carried out in processing steps other than the order shown in the flow chart of FIG. 3, and an appropriate processing step may be added or the processing step may be omitted.
- a water washing step is performed to remove dust and dirt from the metal surface prior to the surface treatment of the copper alloy.
- the water washing step may be carried out, for example, by putting a copper alloy piping device into a tank (not shown), manually rocking it, and then immersing it.
- the surface of the casting surface of the copper alloy is extremely uneven, and if removal is not sufficient in a single faucet step, dust, dirt, etc. sticking to the surface may cause uneven reaction or deterioration of the surface treatment solution in the subsequent surface treatment step. It can be Therefore, if necessary, the faucet process may be carried out again, or a common use with ultrasonic cleaning or a degreasing agent may be used.
- the surface treatment step is carried out to remove Bi and Pb on the surface of the copper alloy with nitric acid.
- the nitric acid concentration should be 4-30 mass%, more preferably 10-20 mass%. Therefore, it is possible to enhance the elution prevention effect of Bi and Pb.
- the washing step is carried out by washing with water, and not only nitric acid which has treated the surface of the copper alloy by washing with water but also corrosive products generated on the surface of the copper alloy, for example, black oxide, are removed by the surface treatment.
- the washing step is a pretreatment step of the shot blasting step, and since it is necessary to remove corrosion products as much as possible, it is preferable to use water washing using ultrasonic waves in combination.
- the surface of the copper alloy after the cleaning step has no gloss inherent to copper and is in a browned state.
- the washing solution is wiped off in the drying step.
- the drying step does not necessarily require a heating means, and may be about natural drying.
- processing step for example, in the case of a product such as a valve made of a copper alloy, appropriate processing such as thread processing of a pipe connection portion or cutting processing of a valve seat portion is performed.
- CAC 901, CAC 902, CAC 903 B, CAC 904, CAC 911, CAC 912, etc. as a lead-free copper alloy containing bronze-based Bi.
- lead-free bronze-based copper alloys which can prevent elution of only Pb without containing Bi include CAC411 and CAC804, etc.
- continuous casting alloys CAC411C, CAC804C, CAC901C and CAC902C , CAC 903 C, CAC 904 C, CAC 911 C, and the like.
- CAC 911 in JIS H5120 Cu: 83.0 to 90.6 mass%, Sn: 3.5 to 6.0 mass%, Zn: 4.0 to 9.0 mass%
- Bi The target is one comprising 0.8 to 2.5% by mass, Se: 0.1 to 0.5% by mass, and unavoidable impurities.
- the target is composed of Furthermore, as an example for CAC 912 in JIS H5120, Cu: 83.3-90.4 mass%, Sn: 2.5-5.5 mass%, Zn: 5.0-9.0 mass%, Bi : 0.8 to 1.5% by mass, Se: 0.1 to 0.5% by mass, Ni: 0.2 to 1.0% by mass, P: 0.1 to 0.25% by mass, and unavoidable impurities
- the target is composed of Furthermore, Cu: 84.0 to 88.0 mass%, Fe: 0.02 to 0.2 mass%, Sn: 9.0 to 11.0 mass% as an example for C89325 in the American CDA standard Zn: 1.0 to 5.0% by mass, Bi: 2.7 to 3.7% by mass, Ni: 0.3 to 1.0% by mass, Sb: 0.1 to 0.5% by mass and unavoidable impurities
- the target is composed of Further, as an example for C 89837 in the American CDA standard, Cu: 84.0 to 88.0 mass%, Fe: 0.2 to 0.5 mass%, Sn: 3.0 to
- the copper alloy surface-treated only with nitric acid turns blackish brown due to the oxide scale of CuO, and it is difficult to use as a product as it is.
- this oxide scale can be removed by ultrasonic cleaning and chemical polishing, the surface of the chemically polished work becomes fine but the color tone is different from that of a normal product using shot blast as the final process.
- the surface is so active that it is easily discolored by hand and the like, which makes it very difficult to handle.
- Patent Documents 1 to 3 The prior art of Patent Documents 1 to 3 is directed to processed parts in piping equipment, for example, a valve in which a cast material is screwed, whereas the present invention relates to parts before processing.
- the object to be treated is different in that it is intended for castings used for piping equipment and materials immediately after casting.
- the Bi elution prevention method of the present invention is suitable for, for example, water contact products such as valves, fittings, pipes, water faucets, water supply and hot water supply products.
- members and parts suitable for the Bi elution prevention method of the present invention are particularly water-contacting parts such as valves and faucets, that is, ball valves, empty balls in ball valves, butterfly valves, gate valves, glove valves , Check valve, Water faucet, Mounting hardware such as water heater and hot water washing toilet seat, Water supply pipe, Connection pipe and pipe joint, Refrigerant pipe, Electric water heater parts (Casing, gas nozzle, pump parts, burners, etc.), Strainer, Water meter Parts, parts for underwater sewerage, drainage plugs, elbow pipes, bellows, connection flanges for toilet bowls, spindles, joints, headers, headers, fork plugs, hose nipples, faucet fittings, water stopcocks, water supply and drainage faucet supplies, sanitary ware fittings Can be widely applied to fittings for hoses for showers, adapters for header tubes, parts for water meters, and other parts and components. That.
- the nitric acid concentration and treatment time which can remove lead and Bi effectively, in the above-mentioned surface treatment process, the nitric acid concentration and treatment time are changed, surface treatment is applied to the casting surface of copper alloy, and the result is confirmed.
- the copper alloy to be used is made into the sample 1 and the chemical component value of this sample 1 is shown in Table 2.
- the sample 1 has a high Pb of 0.47 mass%, which is out of the composition range of CAC911.
- the amount of Pb in CAC 911 is as small as 0.05 to 0.1 mass%, but by making the content of Pb high, it becomes easy to grasp the tendency of the state of removal of Pb. For this reason, the content ratio of Pb of this sample 1 was increased.
- Table 3 shows the measurement results of Bi on the cast surface of the sample 1 by XGT (fluorescent X-ray analyzer) after surface treatment
- Table 4 shows the measurement results of Pb, and these are shown in the graph of FIG.
- the unit of the number which shows the ratio of content of Bi in Table 3, Table 4 is mass%.
- the nitric acid concentration capable of removing Bi was 4 to 40 mass%, more preferably 10 to 25 mass%.
- the treatment time at this time is preferably 5 minutes or more, more preferably 10 minutes or more. It was confirmed that Bi can be effectively removed by performing the surface treatment under these conditions.
- nitric acid can remove Pb.
- Pb As to the removal of Pb, it is conventionally known that a lower nitric acid concentration is preferable, and therefore, in the case of a copper alloy containing both Pb and Bi, in order to effectively remove Bi, a table is shown. 1. From the results in Table 2, it was confirmed that it is desirable to carry out the surface treatment under the conditions that the nitric acid concentration is 10 to 20 mass% and the treatment time is 10 minutes or more.
- the value of Bi is 0.34 wt% for Bi when the nitric acid concentration is increased to 4% and 6% with respect to 1.06 wt% for untreated (nitric acid concentration 0%, treatment time 0 min) It is reduced to 0.34 wt%, and it is shown that Bi is preferentially removed.
- the Pb value is 0.08 wt% and 0. 1%. It is reduced to 08 wt%, and it is shown that Pb is also preferentially removed.
- the standard value of the Bi elution amount in the NSF leaching test is 100 PPb, and in the case of the product before surface treatment with nitric acid, it will be approximately 100 to 150 PPb. Therefore, if the elution amount is suppressed to about 50% (50 to 75 PPb), the reference value can be sufficiently satisfied. Therefore, since the area ratio of Bi is 1.06% in Table 3, it is understood that the area ratio of Bi should be 50% or less, so the upper limit of the area ratio of Bi is 0.53% or less It becomes.
- the dissolution standard value of Bi is 0.65% when the nitric acid concentration is 3%, and 0.68% when the nitric acid concentration is 40%.
- the dissolution criterion of Bi is 0.34% when the nitric acid concentration is 4%, and 0.39% when the nitric acid concentration is 30%, both of which pass. Therefore, it is necessary to make nitric acid at a concentration of 4 to 30 mass%, which preferentially dissolves Bi and selectively removes Bi. From the results of Mini-SEM observation before and after treatment with CAC 911 20% nitric acid for 10 minutes in Table 7 and FIG. 9, it was confirmed that Bi was selectively removed.
- CAC 911 surface area of 32.4 cm 2 of a sample having a polished surface
- the elution amount of Sn, Zn, Bi, Se, Pb, and Cu after the surface treatment was analyzed, and this was converted into a percentage to determine the elution ratio of each element.
- analysis values of 20% nitric acid solution (blank) before treatment were also confirmed.
- sample 2 In order to measure the optimum shot blasting time and shot ball diameter at the time of shot blasting, a CAC 911 casting having the chemical component values shown in Table 5 is used as sample 2 and this sample 2 is 10 mass% with 20 mass% nitric acid. After the treatment, shot blasting was performed under the conditions shown in Table 6, and Bi and Pb on the shot skin surface were analyzed by XGT. The chemical component values of Sample 2 are shown in Table 5, the conditions of shot blasting and the measurement results of Bi and Pb after shot blasting are shown in Table 6, respectively.
- the leaching amount of Pb is high, because the content ratio of Pb of the sample 1 is set high as described above. Therefore, as shown in Table 8, when the copper alloy in which the content ratio of Pb is reduced compared to the sample 1 is used as the sample 3, the same leaching test as described above is performed on the sample 3
- the lead leaching amount of Pb was 1.3 ppb, which could be reduced to a desirable leaching amount of 5 ppb or less.
- the leaching amount of Bi is 25.4 ppb, and the leaching amount is low as in the case of the sample 1.
- the thickness of the cast surface scraped off by shot blasting is estimated.
- Sample 1 was used as the copper alloy at this time, and the number was 84, the surface area was 112.95 cm 2 , and the specific gravity was 8.75.
- shot balls during shot blasting were ⁇ 0.3 mm stainless steel shot and ⁇ 0.6 mm steel shot.
- the grinding thickness by shot blasting ( ⁇ m) mass loss (g) / (surface area of copper alloy ⁇ specific gravity) ⁇ 10000, and the relationship between the shot time at the time of shot blasting and mass loss / grinding thickness by this formula is It is shown in FIG.
- the grinding thickness (grind amount) when applying a ⁇ 0.3 mm stainless steel shot for 3 minutes is calculated to be at least 0.5 ⁇ m or less.
- the surface of the sample 1 was actually observed, as shown in the photograph of FIG. 6, the surface was scraped off by about 5 ⁇ m, and it showed a tendency different from the value calculated from the mass loss. This is considered to be due to the action of crushing the material surface by shot blasting, and as a result, it is considered that the material appears to be scraped more than the grinding thickness when grinding the material surface.
- mass loss as described above.
- FIG. 7 the microscope picture which expanded the surface of the sample 1 is shown, and in FIG. 7 (a), as-cast surface, FIG.7 (b), 20 mass% nitric acid of FIG. 7 (a)
- FIG. 7 (c) shows a state where FIG. 7 (b) is treated for 5 min with a stainless steel shot of ⁇ 0.3 mm.
- FIG. 7 (a) it was confirmed that a large amount of Bi shown in white exists.
- FIG. 7B the white portion disappears and Bi is removed by the surface treatment with 20 mass% nitric acid, and at the same time, the shot skin is removed and a solid alloy layer immediately below the shot skin can be seen.
- FIG. 7 (c) although the surface of FIG. 7 (b) is crushed by the shot and returns to the shot skin, almost no white part is seen. Most of the white objects seen in FIG. 7C are those observed due to the edge effect unique to SEM (electron microscope), the adhesion different from Bi, and the like.
- SEM electrostatic microscope
- FIG. 8 the cross-sectional structure of the micrograph of the sample 1 is shown, and in FIG. 8 (a), the cross-sectional structure surface-treated with 20 mass% nitric acid, and in FIG. 8 (b) and FIG. 8 (c) Fig. 8 shows cross-sectional structures measured at different positions after treating Fig. 8 (a) with a stainless shot of ⁇ 0.2 mm for 3 minutes.
- FIG. 8 (a) black holes can be seen at the top. This is a place where Bi originally existed, and this Bi was removed by 20 mass% nitric acid. In this case, depending on the form of Bi, it is possible that nitric acid hardly penetrates and Bi which can not be completely dissolved by nitric acid remains in the back of the hole. However, as shown in FIGS. 8 (b) and 8 (c), the presence of holes in which Bi was present was hardly confirmed on the surface after shot blasting. This is considered to be that the opening of the hole was blocked by compressing the alloy surface by shot blasting.
- the shot blast which is mainly intended to remove discoloration, has a role to suppress the elution of Bi remaining in the deep part of the hole.
- the shot blasting time is increased, the surface is scraped and a new Bi is exposed. Therefore, it is preferable to shorten the shot time to such an extent that the color change can be removed.
- the surface area of the test piece was 60 mm 2 and the test conditions were such that the nitric acid concentration was 20%, the treatment time was 10 min, and the surface of the test piece was analyzed.
- the presence of Bi and Pb was determined by XGT analysis (X-ray analysis). The results are shown in Tables 12-14.
- the present invention is a target alloy containing at least the following component ranges.
- B 0 to 16 ppm Mm: 0 to 13 ppm
- Mini-SEM scanning electron microscope
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Public Health (AREA)
- Water Supply & Treatment (AREA)
- ing And Chemical Polishing (AREA)
Abstract
Description
また、鉛の浸出基準もますます厳しくなっており、例えば、鉛レス銅合金に不可避不純物として含まれる微量の鉛であっても浸出基準を満たせないことがある。
このような状況の下、水道用に使用される配管器材には、鉛の溶出を防止した上でBiの溶出を抑えることが重要になっている。
一方、特許文献2には、鉛含有銅合金をアルカリ性のエッチング液からなる洗浄液に浸漬して表面の鉛を除去しようとした鉛溶出低減処理方法が開示されている。
特許文献3の銅合金製材の再生処理方法においては、表2より、27wt%以下の硝酸濃度による化学研磨処理液によって銅合金を処理した場合に、接水部よりBiを除去できる可能性が示唆されている。
また、前述した鉛フリー銅合金には合金中にBiを含有させないようにしたものがあり、これによってBiの溶出を抑制しようとする技術がある。
更に、Biを含有する銅合金において、鉛の溶出を抑えるために鉛の含有量を厳格化すると工場内等で発生するリターン材や市場から回収されるスクラップ材を溶解して再利用することが難しくなり、製品のコストアップが避けられなくなる。
このBi溶出防止方法の第1の方法は、少なくともBiを含有し、例えば、微量の鉛およびBiを含有する水道用の銅合金製のバルブや継手などの表面に存在するBiを、4~20mass%の硝酸によりCuの溶解を抑制させつつBiを優先的に溶解させてBiを除去するようにしている。ここにおいて、優先的な溶解除去とは、銅合金のマトリクスを構成する主要元素(例えばCu)の溶解割合に比して、Biの溶出割合が多いことをいう。この場合、硝酸濃度を10~20mass%とすることがより好ましく、このときにはBiとPbとの双方の溶出を効果的に抑制し、これらの溶出防止を図ることが可能になる。その際、表面処理時間は、5min以上が好ましい。
これは、例えば、同文献3(明細書段落21参照)の発明において、67%濃硝酸を用いて20~27wt%濃度の硝酸を設ける場合、これを60%濃硝酸を用いた場合に換算すると、22.3~30.2wt%濃度の硝酸になるからである。
一方、同文献1に示されている硝酸の濃度範囲についても、60%硝酸に換算した場合には0.6~8.0%硝酸となるため、本実施形態における硝酸の濃度範囲が同文献1と重なることはない。
ショットブラストのショット玉は、例えば、φ0.1~0.6mm、より好ましくはφ0.3~0.6mmの径とすることがよく、これにより酸化スケールによる変色を効果的に除去できる。
この場合、合金表面からの深さDと合金中におけるBi含有量との関係は、図2の傾斜に示すように、合金表面からの深さが深くなるにつれてBi含有量が少なくなり、この傾斜には、逆偏析と呼ばれるBiが合金表面に偏析していることが反映されている。
この図2において、ショットブラストで合金表面を削るときの最大深さDmaxを、硝酸によりBiが除去された後の合金表面からの深さtよりも小さくすることにより、硝酸にでBiを除去した後に、ショットブラストの研磨によりあらたにBiが銅合金表面に表出することを防ぐことができる。図2において、2点鎖線は、硝酸による処理を施さない場合の仮想線を示している。
これらのことから、平均結晶粒径がR(μm)、Bi含有量がX(mass%)の合金における表面処理製品のBi含有量を50~75ppbに抑制するためのショットブラストによる研磨量は、R/2×1.3/X=0.65R/Xと表され、これが研磨量の上限値となる。
以上のことより、研磨により除去される厚さT1を前述の0.1~0.65R/X(μm)とすることで、NSF浸出試験をクリヤでき、Biの溶出量を抑えた製品を提供することが可能になる。
これらのことから、Biの平均結晶粒径がR(μm)、Pb含有量がY(mass%)の合金における処理後製品のPb溶出量を15ppb未満に抑制するためのショットブラストによる研磨量は、15/50×R×0.47/Y=0.141R/Yと表され、これが研磨量の上限値となる。
以上のことより、研磨により除去される厚さT2を前述の0.1~0.141R/Y(μm)とすることで、NSF浸出試験をクリヤでき、Pbの溶出量を15ppb未満に抑えた製品を提供することが可能になる。
よって、研磨により除去される厚さT3を0.1~0.047R/Y(μm)とすることで、NSF浸出試験をクリヤでき、Pbの溶出量を5ppb未満に抑えた製品を提供することが可能になる。
洗浄工程後には、図3に示すように、乾燥工程において洗浄液を拭き取るようにする。この乾燥工程は、必ずしも加熱手段は必要なく、自然乾燥程度でよい。
また、JIS H5120におけるCAC911を対象とする一例として、Cu:83.0~90.6質量%、Sn:3.5~6.0質量%、Zn:4.0~9.0質量%、Bi:0.8~2.5質量%、Se:0.1~0.5質量%、及び不可避不純物から構成されるものを対象とする。
また、JIS H5120におけるCAC912を対象とする一例として、Cu:83.3~90.4質量%、Sn:2.5~5.5質量%、Zn:5.0~9.0質量%、Bi:0.8~1.5質量%、Se:0.1~0.5質量%、Ni:0.2~1.0質量%、P:0.1~0.25質量%、及び不可避不純物から構成されるものを対象とする。
更に、アメリカCDA規格におけるC89325を対象とする一例として、Cu:84.0~88.0質量%、Fe:0.02~0.2質量%、Sn:9.0~11.0質量%、Zn:1.0~5.0質量%、Bi:2.7~3.7質量%、Ni:0.3~1.0質量%、Sb:0.1~0.5質量%及び不可避不純物から構成されるものを対象とする。
また、アメリカCDA規格におけるC89837を対象とする一例として、Cu:84.0~88.0質量%、Fe:0.2~0.5質量%、Sn:3.0~4.0質量%、Zn:6.0~10.0質量%、Bi:0.7~1.2質量%、Ni:0.3~1.0質量%、Sb:0.1~0.5質量%及び不可避不純物から構成されるものを対象とする。
また、本発明のBi溶出防止方法により、BiやPbを効果的に溶出防止できる黄銅系の材料としては、例えば、C6803等のBi-Se系鉛フリー黄銅材料、C6801等のBi系鉛フリー黄銅材料などがある。
Pbの除去に関しては、硝酸濃度が低いほうが好適であることが従来より知られているため、PbとBiとの両者を含有する銅合金の場合にBiを効果的に除去するためには、表1、表2の結果より、硝酸濃度を10~20mass%、処理時間を10min以上とする条件によって表面処理を実施することが望ましいことが確認された。
また、Pbの値も、未処理(硝酸濃度0%、処理時間0min)における0.41wt%に対し、硝酸濃度を4%、6%と上げて処理すると、Pbは0.08wt%、0.08wt%と減っており、Pbも優先的に除去されている状態が示されている。
硝酸濃度が25%以上となると、Pbが0.14wt%と増え、Pbの溶解性能が低下する傾向を示す。また、硝酸濃度が30%以上となると、Biが0.39wt%と増え、Biの溶解性能も低下する傾向を示す。
このように、ショットブラストにより1μm程度表面が削り取られた場合、露出するBi以上のBiの存在は無く、5μm程度の表面押し込みによりBiが表面に露出することは無いことが確認された。
このように、本来は変色除去を主目的とするショットブラストには、穴の奥底に残存するBiの溶出を抑制する役割も確認された。ただし、ショットブラストの時間を長くすると、表面が削られて新たなBiが露出するため、変色を除去できる程度にショット時間を短くすることが好ましい。
テストピースの表面積は60mm2であり、試験条件は、硝酸濃度20%、処理時間10min、テストピースの表面を分析した。BiとPbの存在をXGT分析(X線分析)で行った。その結果を表12~表14に示す。
Cu:57.7~90.1
Sn:0.00~9.40
Zn:0.12~40.55
Bi:0.28~4.55
Se:0.00~0.78
Sb:0.00~0.21
P:0~1380ppm
Pb:0.01~0.36
Ni:0.00~22.07
Fe:0.00~0.87
Si:0.00~3.09
Al:0.00~0.72
B:0~16ppm
Mm:0~13ppm
一方、合金によって、Biの除去率に差があることから、表面のBiの分布をMini-SEM(走査型電子顕微鏡)により定性的に確認した(図10~16参照)。この結果によると、全ての銅合金の組成でBiとPbが除去されることが確認された。
Claims (5)
- 少なくともBiを含有する銅合金の表面に存在するBiを、4~20mass%の濃度の硝酸によりCuの溶解を抑制させつつBiを優先的に溶解させて当該Biを選択除去することを特徴とする銅合金のBi溶出防止方法。
- 前記硝酸濃度を10~20mass%とすることにより、BiとPbの溶出を選択除去した請求項1に記載の銅合金のBi溶出防止方法。
- 少なくともBiを含有する銅合金の表面に存在するBiを硝酸により除去した後、銅合金の表面にショットブラストを施すことにより、硝酸により生じた酸化物などの腐食性生物を除去し、且つ表面の光沢化を図ることを特徴とする銅合金のBi溶出防止方法。
- 硝酸によるBi除去により銅合金表面に形成された空隙部の深さ範囲内で前記ショットブラストを施すことにより、銅合金の内方に存在するBiの露出を抑制した請求項3に記載の銅合金のBi溶出防止方法。
- 硝酸によるBi除去により、銅合金表面に形成された空隙部をショットブラストを施して閉塞することにより、銅合金の内方に存在するBiの露出を抑制した請求項4に記載の銅合金のBi溶出防止方法。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012501057A JP5037742B2 (ja) | 2010-08-24 | 2011-08-24 | 銅合金のBi溶出防止方法 |
CA2807637A CA2807637C (en) | 2010-08-24 | 2011-08-24 | Method for preventing elution of bi from copper alloy |
US13/817,187 US10000854B2 (en) | 2010-08-24 | 2011-08-24 | Method for preventing elution of Bi from copper alloy |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010-187598 | 2010-08-24 | ||
JP2010187598 | 2010-08-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012026490A1 true WO2012026490A1 (ja) | 2012-03-01 |
Family
ID=45723483
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2011/069048 WO2012026490A1 (ja) | 2010-08-24 | 2011-08-24 | 銅合金のBi溶出防止方法 |
Country Status (4)
Country | Link |
---|---|
US (1) | US10000854B2 (ja) |
JP (1) | JP5037742B2 (ja) |
CA (1) | CA2807637C (ja) |
WO (1) | WO2012026490A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015208842A (ja) * | 2014-04-30 | 2015-11-24 | 株式会社キッツ | 低鉛黄銅製接液部材の製造方法とその接液部材 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10806101B2 (en) | 2016-04-14 | 2020-10-20 | Mycotechnology, Inc. | Methods for the production and use of myceliated high protein food compositions |
BR112018070148A2 (pt) | 2016-04-14 | 2019-05-07 | Mycotechnology Inc | métodos para a produção e uso de composições alimentícias de alto teor proteico miceliadas |
US11166477B2 (en) | 2016-04-14 | 2021-11-09 | Mycotechnology, Inc. | Myceliated vegetable protein and food compositions comprising same |
WO2020061502A1 (en) | 2018-09-20 | 2020-03-26 | The Better Meat Company | Enhanced aerobic fermentation methods for producing edible fungal mycelium blended meats and meat analogue compositions |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1129887A (ja) * | 1997-07-14 | 1999-02-02 | Kitz Corp | 金属製バルブ・管継手等の金属製配管器材の鉛溶出防止法及びその金属製配管器材 |
JPH11510217A (ja) * | 1995-08-03 | 1999-09-07 | エウロパ メタリ ソチエタ ペル アチオニ | 鉛放出性の低い鉛含有銅合金製配管部材およびその製造法 |
JP2001089883A (ja) * | 1999-09-22 | 2001-04-03 | Daido Steel Co Ltd | チタン又はチタン合金製品の製造方法 |
JP2008088526A (ja) * | 2006-10-04 | 2008-04-17 | Kitz Corp | 水道メータなどの銅合金製材の再生処理方法 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6461534B2 (en) | 1997-11-19 | 2002-10-08 | Europa Metalli S. P. A. | Low lead release plumbing components made of copper based alloys containing lead, and a method for obtaining the same |
EP1038990B1 (en) | 1997-12-03 | 2008-06-04 | Toto Ltd. | Method of reducing elution of lead in lead containing copper alloys for drinking water service |
CN1303242C (zh) * | 2002-09-03 | 2007-03-07 | 杰富意钢铁株式会社 | 结构用Cr钢和它的制造方法 |
JP4197269B2 (ja) * | 2002-09-09 | 2008-12-17 | 株式会社キッツ | バルブ・管継手等の銅合金製配管器材のニッケル溶出防止法及びその銅合金製配管器材 |
US8182879B2 (en) * | 2004-03-05 | 2012-05-22 | Kitz Corporation | Method for preventing elution of nickel from water-contact instrument of copper alloy by formation of a protective film |
DK1777305T3 (da) * | 2004-08-10 | 2011-01-03 | Mitsubishi Shindo Kk | Støbning af kobberbaselegering med raffinerede krystalkorn |
-
2011
- 2011-08-24 US US13/817,187 patent/US10000854B2/en active Active
- 2011-08-24 WO PCT/JP2011/069048 patent/WO2012026490A1/ja active Application Filing
- 2011-08-24 CA CA2807637A patent/CA2807637C/en active Active
- 2011-08-24 JP JP2012501057A patent/JP5037742B2/ja active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11510217A (ja) * | 1995-08-03 | 1999-09-07 | エウロパ メタリ ソチエタ ペル アチオニ | 鉛放出性の低い鉛含有銅合金製配管部材およびその製造法 |
JPH1129887A (ja) * | 1997-07-14 | 1999-02-02 | Kitz Corp | 金属製バルブ・管継手等の金属製配管器材の鉛溶出防止法及びその金属製配管器材 |
JP2001089883A (ja) * | 1999-09-22 | 2001-04-03 | Daido Steel Co Ltd | チタン又はチタン合金製品の製造方法 |
JP2008088526A (ja) * | 2006-10-04 | 2008-04-17 | Kitz Corp | 水道メータなどの銅合金製材の再生処理方法 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015208842A (ja) * | 2014-04-30 | 2015-11-24 | 株式会社キッツ | 低鉛黄銅製接液部材の製造方法とその接液部材 |
Also Published As
Publication number | Publication date |
---|---|
JP5037742B2 (ja) | 2012-10-03 |
CA2807637A1 (en) | 2012-03-01 |
CA2807637C (en) | 2018-09-11 |
JPWO2012026490A1 (ja) | 2013-10-28 |
US20130142691A1 (en) | 2013-06-06 |
US10000854B2 (en) | 2018-06-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2012026490A1 (ja) | 銅合金のBi溶出防止方法 | |
US8221556B2 (en) | Copper alloy plumbing hardware, such as valves and tube couplings, and the treatment method for reducing elution of lead | |
JP6266737B2 (ja) | 耐応力腐食割れ性に優れた黄銅合金と加工部品及び接液部品 | |
JP4588698B2 (ja) | 銅合金製接液器材のニッケル溶出防止方法及びニッケル溶出防止用保護膜形成剤 | |
JP3345569B2 (ja) | バルブ・管継手等の銅合金製配管器材の鉛溶出防止法及びその銅合金製配管器材 | |
JP5826739B2 (ja) | 保護膜形成剤の管理方法 | |
JP6374688B2 (ja) | 水栓金具又はバルブにおける銅合金製給水器材の製造方法 | |
TWI392752B (zh) | 低鉛銅合金 | |
JP5180644B2 (ja) | 銅合金製接液器材のニッケル溶出防止方法 | |
JP4047188B2 (ja) | バルブ・管継手等の銅合金製配管器材の鉛溶出低減処理方法 | |
JP3830841B2 (ja) | バルブ・管継手等の配管器材 | |
JP6542425B2 (ja) | 水栓金具又はバルブにおける銅合金製給水器材の製造方法 | |
JP4717773B2 (ja) | 水道メータなどの銅合金製材の再生処理方法 | |
JP2018165406A (ja) | 水栓金具又はバルブにおける銅合金製給水器材の製造方法 | |
JP2004250726A5 (ja) | バルブ・管継手等の銅合金製配管器材の鉛溶出低減処理方法 | |
JP2000212662A (ja) | 耐酸性腐食性に優れた黄銅材及び黄銅管材、黄銅製品 | |
US20110081271A1 (en) | Low-lead copper alloy | |
JP2002317284A (ja) | バルブ・管継手等の銅合金製配管器材 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 2012501057 Country of ref document: JP |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11819953 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2807637 Country of ref document: CA |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13817187 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 11819953 Country of ref document: EP Kind code of ref document: A1 |