JP2011007220A - Ball for ball valve, plating method thereof, and ball valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball for a ball valve, a plating method thereof and a ball valve, in which abrasion resistance is improved and chlorine resistance or resistance to dezincification is improved, suppressing the elution of a harmful substance and satisfying both of sliding property and sealing performance.SOLUTION: In the ball for the ball valve, an SnNi alloy plating layer 4 whose film thickness is larger than 0.5 μm and equal to or less than 3 μm is formed on a covering surface 3 of a substrate 2 of a copper or copper alloy made ball valve body. A method for plating the ball for the ball valve includes attaching the ball valve body to a jig, immersing the ball valve body in a vessel storing SnNi alloy plating solution, then forming SnNi alloy plating on the covering surface of the substrate of the ball valve body by feeding electricity to the ball valve body and plating solution. The ball valve contains the ball valve body in which SnNi alloy plating is formed in the inside of the body having an inlet port and an outlet port through a ball seat. The ball valve body is provided rotatably through a stem.

Description

  The present invention relates to a ball valve ball, and more particularly, to a ball valve ball plated, a plating method thereof, and a ball valve.

  The ball for a ball valve is mounted in a valve body while being supported by a ball seat, and has a structure in which the ball is rotated via a stem provided on the ball. Therefore, the ball needs to exhibit its slidability and sealability while ensuring slidability with respect to the ball sheet, and is also required to have wear resistance against repeated rotational operations. It is also necessary to exhibit chlorine resistance and dezincification resistance against highly corrosive fluids. In order to satisfy these requirements, the ball surface is usually plated. When the ball is plated, the ball is slidable, sealable, wear resistant, chlorine resistant and resistant. Dezincification corrosivity is required.

Examples of this type of ball plating process include hard Cr plating and Cr plating such as NiCr plating. These Cr platings are applied for the purpose of improving the surface hardness of the ball and improving the corrosion resistance by the passivation film.
Moreover, as plating treatment other than Cr plating, for example, there is SnNi alloy plating treatment, and as a faucet fitting subjected to this SnNi alloy plating treatment, for example, there is a faucet fitting of Patent Document 1. The faucet fitting of the literature 1 has a SnNi alloy plating layer with a thickness of 0.5 to 2 microns on the surface of the material fabric with respect to the main body of the faucet made of copper or copper alloy and its built-in parts. It has been applied.
On the other hand, the faucet fitting of Patent Document 2 is a faucet body made of copper or a copper alloy, and a Sn-based plating layer is formed on the surface near the valve seat inside.

  By the way, when the ball is plated, generally, electroplating called a hook plating method (rack method) is used. The hook plating method hangs a workpiece on a jig called a rack, hangs it on a cathode bar called a busper, immerses it in a plating solution, and applies current between the plate-like anode to the workpiece. This is an electroplating method for plating. According to the electroplating using the hook plating method, it is possible to avoid contact between objects to be processed, that is, balls, and thus the surface to be processed is prevented from being scratched and the surface becomes smooth. .

Japanese Patent No. 3119309 JP-A-6-193758

  However, the above-described Cr plating such as hard Cr plating and NiCr plating is liable to generate fine cracks due to internal stress and to easily generate pinholes, so that it is difficult to coat the surface of the ball surface to the micron level. In addition, as shown in JIS H8501, the ball valve subjected to the plating treatment is plated with a corrosive fluid such as hydrochloric acid or phosphoric acid, and the passivation film of Cr is destroyed by these fluids. May be removed. For this reason, the balls plated with Cr are not suitable for flowing a tap water having a high chlorine concentration or a fluid containing a phosphoric acid component. If these fluids are made to flow, it becomes necessary to coat the ball with a film showing another corrosion resistance such as PTFE, which leads to an increase in the overall cost.

  In addition, for example, when measuring Cr plating components using a simple measuring instrument such as an X-ray fluorescence apparatus, hexavalent chromium and general metals regulated by the European RoHS directive contained in Cr plating It becomes difficult to distinguish from Cr, and as a result, there is a risk of not knowing whether hexavalent chromium harmful to the human body is contained during Cr plating. Further, in recent years, in WHO and the like, the elution amount of Ni is also regulated in addition to the regulation of the elution amount of Pb. However, when balls are plated by NiCr plating, Ni is eluted and has an adverse effect on the human body. There is also a risk of affecting.

  On the other hand, the SnNi alloy plating in Patent Document 1 and Patent Document 2 is intended for internal parts such as a wetted part near the water tap and a sliding member, and for the purpose of ensuring the sliding property of the sliding member. The plating film thickness is thin. In this case, for example, in the literature 1, the SnNi alloy plating layer has a maximum thickness of 2 microns. However, if the ball is to be plated with this thickness, the surface of the ball is a curved surface, so that the uniform plating film thickness is obtained. In some cases, a thin plated portion is formed on the ball surface, and a portion having poor sliding properties, sealing properties, and wear resistance may be generated. As a countermeasure against this, it is conceivable to apply the underlying Ni plating to the lower layer side of the SnNi alloy plating. In this case, the number of plating processes is increased, and in the heated state, the SnNi alloy plating is caused by the difference in expansion coefficient. There is a risk of peeling from the Ni plating.

  Moreover, when the balls are Cr plated or SnNi plated, when the balls are suspended between the electrodes by the hook plating method, the distance from the electrodes to the balls is not constant because the balls are spherical. There is a macroscopic difference in current density between the upper and lower poles and the vicinity of the electrodes. Therefore, it becomes more difficult to apply a uniform thickness plating process to the ball. For example, in Patent Document 1, when a plating process is performed with a film thickness of 0.5 microns, the plating film on both sides of the ball The thickness may be smaller than the plating film thickness near the electrode.

The plating thickness of electroplating is generally said to be proportional to the processing time, but it has been found that in practice it is greatly influenced by the density of current applied to the surface of the object to be processed. In this case, if the surface of the object to be processed is convex, the current density tends to increase, and if it is concave, the current density becomes low. If the unevenness difference increases, the current density difference also increases and the plating thickness tends to further differ. . Furthermore, this phenomenon becomes more prominent when the workpiece and the electrode are fixed, and the electrode is fixed to the micro uneven portion of the workpiece generated by chemical polishing performed before cutting or plating. As a result, a significant current density difference occurred in the uneven portion, and the surface roughness of the plating of the entire ball substrate was rough.
In this way, when plating the ball, the plating film thickness is insufficient, or the difference in surface irregularities due to this thin film thickness becomes severe, resulting in predetermined slidability, sealing performance, and wear resistance. May not be obtained.

  The present invention has been developed as a result of intensive studies in view of the above-described circumstances, and the object of the present invention is wear resistance while suppressing leaching of harmful substances while achieving both slidability and sealing performance. It is an object of the present invention to provide a ball for a ball valve, a plating treatment method thereof, and a ball valve that have improved properties and improved chlorine resistance and dezincification corrosion resistance.

  In order to achieve the above object, the invention according to claim 1 is a ball in which an SnNi alloy plating layer having a thickness of 0.5 μm <film thickness ≦ 3 μm is provided on a coated surface of a ball valve body made of copper or copper alloy. This is a valve ball.

  The invention according to claim 2 is a ball for a ball valve excellent in chlorine resistance and dezincification corrosion resistance, wherein the film thickness is 2 μm <film thickness ≦ 3 μm.

  The invention according to claim 3 is a ball for ball valve excellent in chlorine resistance and dezincification corrosion resistance in which the alloy ratio of SnNi alloy plating is 65% ≦ Sn <75%.

  The invention according to claim 4 attaches a ball valve body to a jig, immerses the ball valve body in a container containing SnNi alloy plating treatment liquid, and then energizes the ball valve body and the plating treatment liquid. This is a ball valve ball plating method in which the coated surface of the base of the ball valve body is subjected to SnNi alloy plating.

  According to the fifth aspect of the present invention, a ball valve body that has been subjected to SnNi alloy plating is incorporated through a ball seat in a body having an inflow port and an outflow port, and the ball valve body can be rotated through a stem. It is a ball valve provided.

  According to the first aspect of the present invention, since the SnNi alloy plating layer having a thickness of 0.5 μm <film thickness ≦ 3 μm is provided on the clothing surface of the base of the ball valve body, harmful substances to the human body such as Ni and Pb While suppressing elution, the wear resistance is improved while achieving both sliding and sealing properties. In addition, chlorine resistance and dezincification corrosion resistance can be improved, and even when a corrosive fluid such as hydrochloric acid or phosphoric acid flows, the peeling of the plating layer is prevented and chemical resistance and durability are improved. be able to. Furthermore, by providing a SnNi alloy plating layer directly on the coated surface made of copper or copper alloy, a plating layer can be formed while generating an intermetallic compound therebetween, and the throwing effect is exhibited by this intermetallic compound. Both are firmly connected to each other, and the plating layer is prevented from peeling off.

  According to the invention which concerns on Claim 2, plating with a predetermined | prescribed film thickness can be provided in the whole coating surface of the base of the ball valve body which is a spherical surface. In addition, even when it is difficult to uniformly apply plating to the entire coated surface, it is possible to apply a predetermined thickness to the entire spherical surface of the coated surface, and the difference in unevenness on the coated surface is severe. In addition, the plating treatment can be performed with fine surface roughness, and the functionality of chlorine resistance and dezincification corrosion resistance of SnNi alloy plating can be further enhanced. Moreover, since the upper limit of the film thickness of SnNi alloy plating is 3 micrometers or less, generation | occurrence | production of the internal stress to the plating surface can be prevented and generation | occurrence | production of a crack can be prevented.

  According to the third aspect of the invention, a strong plating layer can be obtained by obtaining a metastable NiSn phase exhibiting the maximum internal stress. Moreover, the smoothness of the plating surface side can be improved.

  According to the invention of claim 4, the plating treatment can be performed without causing scratches on the surface of the ball valve body, and a plating layer having a predetermined thickness or more is provided on the entire coated surface, so In addition, the ball valve ball can be provided with high wear resistance and high sealing performance, and excellent in chlorine resistance and dezincification corrosion resistance.

  According to the invention of claim 5, while preventing the elution of Ni and Pb which are harmful substances to the human body, the wear resistance is improved while achieving both the sliding property and the sealing property, and the chlorine resistance and resistance. A ball valve excellent in dezincification corrosion resistance can be provided.

It is sectional drawing which shows a ball valve. It is a schematic diagram which shows a hook plating method. It is a schematic diagram which shows the coating state of the plating at the time of electroplating. It is a schematic diagram which shows a plating processing apparatus. It is the perspective view which showed the holding | maintenance state of the base. It is a photograph which shows the specimen after a steam endurance test. It is a photograph which shows the other test sample after a steam endurance test. It is a photograph which shows the comparative product after a steam endurance test. It is a photograph which shows the other comparative product after a steam endurance test. 6 is a photograph showing still another comparative product after the steam durability test. It is a photograph which shows the specimen after a heating test. It is a schematic diagram which shows the test apparatus in a high temperature chlorine water endurance test. It is a photograph which shows the test sample after a high temperature chlorine water durability test. It is a schematic diagram which shows the other test apparatus in a high temperature chlorine water durability test. It is a photograph which shows the state after the high temperature chlorine water endurance test of the comparative product which gave CuSn plating. It is the schematic diagram which showed the measurement location in a dezincification corrosion resistance test. It is a photograph which shows the specimen after a dezincification corrosion resistance test. It is a photograph which shows the state after the dezincification corrosion resistance test of the test article which gave SnNi alloy plating to leadless dezincification resistance brass. It is a photograph which shows the state after the dezincification corrosion resistance test of the comparative product of leadless dezincification brass.

Embodiments of a ball valve ball, a plating method thereof, and a ball valve according to the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a ball valve equipped with the ball valve ball of the present invention. The ball body 1 is configured by providing a SnNi alloy plating layer 4 on a covering surface 3 of a base 2 of a ball valve body. The base 2 of the ball valve body is made of copper or a copper alloy, and is made of C3771 brass in this embodiment. In this case, a low Pb or Pb-less copper alloy described later may be used. The covering surface 3 includes an outer surface 2a of the substrate 2 and a flow path (inner peripheral surface) 2b.

  The film thickness of the SnNi alloy plating layer 4 is in the range of 0.5 μm <film thickness ≦ 3 μm. In this case, the reason for 0.5 μm <film thickness is proportional to the plating process time. However, if the film thickness is 0.5 μm or less, the scratches can reach the substrate when foreign matter in the fluid collides when the ball valve is operated repeatedly at room temperature or in a state where steam flows. It is because there is a risk of reaching. Further, the reason for setting the film thickness ≦ 3 μm is that the internal stress of the SnNi alloy plating becomes high and cracks are generated on the plating surface.

  Further, the film thickness of the plating layer 4 is more preferably 2 μm <film thickness ≦ 3 μm. In this case, the chlorine resistance and dezincification corrosion resistance of the ball body 1 are more excellent. The reason why the thickness of the plating layer 4 is more preferably 2 μm <film thickness ≦ 3 μm will be described below.

  In electroplating, since plating is formed by an electrochemical reaction, in general, the plating thickness can be estimated in proportion to the processing time. In practice, however, the plating thickness is affected by the current density of the surface being plated. Since the current density is macroscopic or microscopic, the convex portion tends to increase and the concave portion tends to be low. Therefore, if the coating has irregularities, a difference occurs in the electric density and a difference in the plating thickness. It will be.

  When the base 2 is plated by this electroplating, the ball valve has a structure in which the ball seals the fluid and the ball surface is not allowed to be slightly damaged. Usually used. As shown in FIG. 2, in the case of the hook plating method, the position of the covering 10 and the electrode 11 is fixed. Therefore, in the case of a spherical covering 10 such as a ball, a macroscopic current density is likely to occur. .

  In addition, when the covering 10 is cut or chemically polished before plating, micro unevenness occurs, but the position of the electrode 10 is fixed to the unevenness, so the direction of the unevenness Depending on the case, the coating state of the plating may differ. In this case, especially for the microscopic unevenness in the so-called pole portion 12 that is not facing the electrode 10, the recess is difficult to be plated, and the circumferential portion 13 is located facing the electrode 11. Then, it is difficult to coat the concave portions with respect to the micro unevenness.

  As described above, SnNi alloy plating is easy to coat and has good wraparound properties. Therefore, if the processing time is set even with a film thickness of 0.5 μm, the entire substrate 2 can be covered. However, in the case of the substrate 2 made of spherical balls, the macroscopic problem and the microscopic problem overlap with each other, so that the electrode 12 has a pole portion 12 with a thickness of 0.5 μm. The plating coating on the corresponding outer surface side becomes insufficient, and as a result, the substrate 2 may be exposed after the plating process, particularly when the fluid is steam or the like. Therefore, by setting the SnNi alloy plating film thickness to 2 to 3 μm, the wraparound property of the SnNi alloy plating is utilized, and the portion corresponding to the pole portion 12 of the outer surface 2a is also coated with a certain thickness. Is possible.

In this case, as shown in FIG. 3 (a), the diameter _{D 2} of the circumferential portion 13 than the diameter _{D 1} of the pole portion 12 side after plating, for example, about 2~3μm longer, ball body 1 is oval Risk that the accuracy of the sphericity will be reduced. However, a ball valve plated with a SnNi alloy plating with a thick film thickness of 2 to 3 μm prevents the peeling of the plating on the surface corresponding to the pole portion 12 even when a steam durability test is performed, The sealing performance as a ball valve is not affected. FIG. 3B shows a case where the plating film thickness is, for example, 0.5 μm or less. At this time, the difference between the diameter D ₃ on the pole portion 15 side after plating and the diameter D ₄ of the circumferential portion 16 is as follows. The covering 10 (substrate 2) may be exposed on the pole 15 side.

Further, the ball body 1 subjected to SnNi alloy plating is excellent in chlorine resistance and chemical resistance, and is also excellent in dezincification corrosion resistance. As this dezincification corrosion resistance, for example, the maximum dezincification erosion depth when the test is carried out by the dezincification corrosion test (ISO-6509) is almost 0 (μm). Thereby, the ball valve body 1 is excellent in dezincification corrosion (erosion) resistance, and a dense plating layer 4 that prevents a chemical solution or the like from penetrating into the substrate 2 is formed. The ball body 1 can have a plating layer 4 that is difficult to pinhole and has extremely high coverage and wraparound.
Moreover, since the SnNi alloy plating layer 4 is provided on the coating surface 3 by a plating method, for example, it is superior in cost compared with a method in which it is coated with PTFE.

Moreover, by coating the SnNi alloy plating layer 4 directly on the base 2 made of copper or copper alloy, the Sn component in the SnNi alloy plating and the copper alloy constituent metal elements are both diffused and the layers of each other are diffused. To dissolve. In this way, an intermetallic compound is formed between them, and the anchoring effect (anchor effect) at the nano level is exhibited to improve the adhesion, so that the ball body 1 is strong after heat is applied or a thermal shock is applied. Even when force is applied, peeling and cracking of the plating layer 4 are prevented.
In the same dezincification corrosion test (ISO-6509), the erosion depth of the base without the plating layer is 1000 to 1200 μm, and the erosion depth when NiCr alloy plating is performed is 400 to 600 μm. Compared with the case where the SnNi alloy plating layer 4 is applied, it is greatly inferior.

By the way, the alloy plating of Sn and Ni forms an intermetallic compound as described above. At this time, Sn and Ni have different properties from Ni. In this case, the mixing ratio of Sn and Ni corresponds to a mixed phase of Ni ₃ Sn ₂ + Ni ₃ Sn ₄ in the composition of the phase diagram of the molten alloy, but the metastable NiSn that does not appear in the alloy phase diagram in the plating alloy The phase is obtained, and Sn is in a range occupying 65 to 74%. Since this NiSn phase exhibits the maximum internal stress in the alloy plating, a strong (hard) plating layer can be obtained in a range where this Sn occupies 65 to 74%. On the other hand, in a range where a metastable NiSn phase cannot be obtained, that is, Sn <65% and Sn ≧ 75%, the plating is poor and the plating surface also lacks smoothness.
Therefore, the alloy ratio of SnNi alloy plating of the plating layer 4 in the ball valve ball of the present invention is set to 65% ≦ Sn <75%.

In addition to the ball for the ball valve, the plating treatment described above can be applied to components such as a valve stem, joint components, and piping equipment components.
The base of the ball valve body described above may be made of a material other than C3771, for example, brass, bronze, or a lead-free copper alloy containing no lead. In this case, examples of the lead-less copper alloy include Bi (bismuth), Bi and Se (selenium), or a copper alloy containing silicon as an alternative to lead.

  Next, a method for plating a ball for a ball valve will be described. In this example, the substrate 2 is plated by the hook plating method described above. FIG. 4 shows an example of a plating apparatus for forming the plating layer 4 on the substrate 2 by the hook plating method. As shown in the figure, the plating apparatus 20 includes a container 21, a jig (rack) 22, and an energization electrode portion 23.

  In the plating apparatus 20, the ball valve element base 2 is attached to and held by a jig 22. The jig 22 has a holding portion 24 that is formed of a wire or the like and is provided in a frame shape at an appropriate interval. As shown in FIG. 5, the substrate 2 is held by the holding portion 24 in a state where the holding portion 24 is passed through the flow path 2b. Furthermore, each substrate 2 is attached to each jig 22 in this state in a so-called tuft shape.

  When attaching the substrate 2 to the holding portion 13, as shown in FIG. 5A, the holding side of the substrate 2 in FIG. 1 is directed to the electrode portion 23 side, that is, the arrow direction indicated by the alternate long and short dash line in FIG. When the electrode part 23 is energized, the substrate 2 is plated from the direction of the sliding surface. In this case, as shown by the broken line in FIG. 5A, the plating film thickness becomes thicker in the vicinity of the sliding surface with the ball sheet 4, and the durability in this vicinity becomes higher.

  On the other hand, FIG. 5 (b) shows a case where the plating process is performed by arranging the support side of the substrate 2 so as to face the electrode part 23. In this case, instead of increasing the plating film thickness on the support side, the plating film thickness in the vicinity of the sliding surface is reduced, resulting in poor durability.

  Further, in FIG. 4, a plating treatment liquid W for electrolytic plating made of a SnNi alloy plating treatment liquid is accommodated in the container 21. Moreover, the electrode part 23 is provided in the container 21, and this electrode part 23 is provided in the appropriate space | interval so that the base | substrate 2 attached to the jig | tool 22 can be arrange | positioned in the meantime.

  Subsequently, when performing the plating process with the plating apparatus 20, the ball valve body (substrate 2) attached to the jig 22 is immersed between the electrode portions 23 of the plating process liquid W, and then the ball valve body. 2 and the plating treatment liquid W are energized through the electrode portion 23 so that the coating surface 3 of the base 2 of the ball valve body is subjected to SnNi alloy plating. In this case, the film thickness of the SnNi alloy plating layer 4 is 0.5 μm <film thickness ≦ 3 μm, or 2 μm <film thickness ≦ 3 μm.

Next, an example of a ball valve equipped with the ball valve ball will be described.
As shown in FIG. 1, the ball valve main body 30 includes a ball main body 1, a body 31, a pair of ball sheets 32 and 32, and a stem 33.
The ball body 1 has a SnNi alloy plating layer 4 formed on the surface of the substrate 2 with a thickness of 0.5 μm <film thickness ≦ 3 μm or 2 μm <film thickness ≦ 3 μm, and has excellent chlorine resistance and dezincification corrosion resistance It has sex. In this case, the alloy ratio of SnNi alloy plating is 65% ≦ Sn <75%.
Moreover, the body 31 has the inflow port 31a and the outflow port 31b, and the ball seat 32 is formed with resin, for example.

As shown in FIG. 1, a ball valve main body 30 includes a ball main body 1 built in a body 31 via a pair of ball seats 32, 32, and the ball main body 1 is rotatably provided via a stem 33. It has a configuration. In this case, the stem 33 is fitted into a mounting recess 34 formed on the upper surface of the ball body 1.
This ball valve is merely an example, and can be applied to a trunnion type ball valve in addition to the floating type shown in FIG. 1, and the internal structure thereof is arbitrary depending on the implementation.

  As described above, in the ball valve ball of the present invention, the SnNi alloy plating layer 4 of 0.5 μm <film thickness ≦ 3 μm is provided on the covering surface 3 of the base 2 of the ball valve body made of copper or copper alloy. As a result, the substrate 7 is coated with a plating layer at the micron level while the anchoring effect is exerted, thereby preventing the occurrence of cracks and pinholes. Further, the SnNi alloy plating layer 4 improves the chlorine resistance and dezincification corrosion resistance, and can be applied to a flow path through which a highly corrosive fluid flows. Moreover, there is no possibility that Ni is eluted like NiCr plating.

  Furthermore, since the thickness of the plating layer 4 is 2 μm <film thickness ≦ 3 μm, the ball body 1 is improved in chlorine resistance and dezincification corrosion resistance, While solving the microscopic problem, a thick film thickness can be formed on the entire substrate 2, and a plating layer having a fine surface roughness can be provided by this film thickness. Thereby, it is possible to improve the wear resistance and improve the durability while achieving both the sliding property and the sealing property of the ball body 1 with respect to the ball sheet 32 without providing a base plating.

  Moreover, since the film thickness of SnNi alloy plating is 3 micrometers or less, generation | occurrence | production of the internal stress of a plating surface can be prevented and generation | occurrence | production of a crack (crack) can be prevented. In this case, if the film thickness of the SnNi alloy plating is larger than 3 μm, an infinite number of cracks may be generated because the internal stress of the plating cannot be endured. The reason is as follows. Although SnNi alloy plating, which is an intermetallic compound, is excellent in chemical resistance, it has a complex crystal structure because it is an intermetallic compound, and has a deformable, small, brittle and hard property. For this reason, the spreadability of the film is poor, and when the film thickness of the plating becomes thick, it becomes impossible to withstand the internal stress.

  Moreover, since the plating layer 4 can be provided on the substrate 2 by the hook plating method using the plating apparatus 20, the entire surface of the substrate 2 can be plated with a thick film thickness. Further, since the energization is performed with the holding side of the ball sheet 32 of the substrate 2 facing the electrode portion 23 and plating is performed from the sliding surface side of the substrate 2, the sliding with the ball sheet 32 is particularly important. It is possible to further improve the slidability and sealability by improving the wear resistance of the moving surface.

Next, the following tests were carried out on the ball valve balls provided with the SnNi alloy plating layer described above, and their sliding properties and sealing properties as well as wear resistance, chlorine resistance, and dezincification corrosion resistance were measured. This was confirmed by the test. At this time, the thickness of the SnNi alloy plating was 2 μm <film thickness ≦ 3 μm. The test methods and test results are described below. First, Example 1 is as follows.
(1) Steam endurance test and thermal test First, a steam endurance test is performed as a test having severe conditions in order to confirm slidability, sealability, and wear resistance of the ball valve ball of the present invention. Then, a thermal test (heating test, thermal shock test) and a deformation test were performed, and the limit of the function of the ball at that time was measured.
As the SnNi alloy plating at this time, an alloy plating with a Sn content ratio of 65% and an alloy plating with a Sn content ratio of 74% were used, and the balls subjected to these plating treatments were designated as a specimen 1 and a specimen 2. Further, in order to compare with the balls subjected to these plating treatments, the comparative product 1 is a ball subjected to SnNi alloy plating with a Sn content ratio of 65% in a film thickness of 0.5 μm, and the comparative product 2 is a ball subjected to NiCr plating. The balls subjected to hard Cr plating were used as comparative products 3, and the same tests were performed on these balls.
In the steam endurance test, the operation was performed up to the destruction level, and the limit of the function was confirmed under the conditions of saturated steam 180 ° C. and 0.98 MPa.

FIGS. 6 and 7 show photographs when the surface of the specimen 1 and specimen 2 after the test is magnified 70 times with a metal microscope and observed on the surface. 6 (a) and 7 (a) are after 1000 operations, and FIG. 6 (b) and FIG. 7 (b) are after 2000 operations, then FIG. 6 (c) and FIG. 7 (c). Fig. 6 (d) and Fig. 7 (d) show photographs after 10,000 operations after 5000 operations.
From the photograph in FIG. 6, discoloration of the specimen 1 was observed after 1000 operations, but no exposure of the substrate to the outside was confirmed even after 10,000 operations. Moreover, also about the sample 2, the exposure to the exterior of a base material was not confirmed after 10,000 times operation | movement. Thus, in the case of any SnNi alloy plating with an Sn content ratio of 65% and 75%, exposure of the brass base can be prevented by setting the film thickness to 2 to 3 μm. It was confirmed that 3 μm below the limit at which SnNi alloy plating causes cracks due to internal stress is more suitable.

  Moreover, the state after operating the comparative product 1 5000 times is shown in FIG. As shown in the figure, the comparative product 1 showed a portion where the plating was peeled off after operating 5000 times. As described above, SnNi alloy plating with a Sn content ratio of 65% with a film thickness setting of 0.5 μm had a portion where the brass substrate was exposed by contact with foreign matter and the like and biting of foreign matter after the vapor durability test. In addition, when it was set as SnNi alloy plating with a Sn content rate of 74%, the brass base was not exposed.

Moreover, the state after the operation of the comparative product 2 is shown in FIG. In FIG. 9, FIG. 9 (a) is operated 1000 times, FIG. 9 (b) is operated 2000 times, FIG. 9 (c) is operated 5000 times, and FIG. 9 (d) is operated 10,000 times. The photograph of the latter state is shown.
As shown in FIG. 9C, the comparative product 2 started to show pitting corrosion after 5000 operations.

Moreover, the state after the operation of the comparative product 3 is shown in FIG. 10 (a) is operated 1000 times, FIG. 10 (b) is operated 2000 times, FIG. 10 (c) is operated 5000 times, and FIG. 10 (d) is operated 10,000 times. The photograph of the latter state is shown.
In the comparative product 3, as shown in FIG. 10 (b), a turtle-shaped pattern appeared after 2000 operations, and this pattern partially peeled after 10,000 operations in FIG. 10 (d).

In addition, an operation durability test in a dry state at a normal temperature on a comparative product 4 in which a SnNi alloy plating with a 0.5 μm plating thickness was applied to a ball and a test sample 3 with a SnNi alloy plating with a 3 μm plating thickness, When the steam operation endurance test was performed, in the normal temperature dry operation endurance test, the comparative product 4 was confirmed to have scratches that had reached the substrate due to the collision of foreign matter, and the test sample 3 was not damaged. On the other hand, in the steam operation endurance test, the comparative product 4 was confirmed to have scratches reaching the substrate due to the biting of foreign matter, and the test sample 3 was not damaged.
Since the thickness of the plating is proportional to the plating processing time, the thinner one is more cost-effective. However, when the thickness is 0.5 μm or less, the above-described problems occur. In addition, SnNi alloy plating has high internal stress, and cracks occur on the plating surface as described above when it exceeds 3 μm.

  On the other hand, the thermal test (heating test, thermal shock test) and deformation test are based on JIS H8504, and the test specimen 4 in which the SnNi plating treatment was applied directly to the base of the copper base alloy and the base Ni plating were applied. The test was conducted with respect to the comparative product 5 which was subjected to SnNi plating after being applied. Table 1 shows the test conditions at this time.

  In the thermal test, the maximum operating temperature of the target ball valve is normally 180 ° C. However, in the thermal test of JIS H8504, the evaluation temperature of NiCr plating on the copper alloy substrate is defined as 300 ° C. In this test, the evaluation temperature was set to 300 ° C. In addition, as a condition for each test, the zinc diffusion phenomenon occurs even at room temperature, but since this diffusion phenomenon is promoted in the heated state, the heating time was set to 30 hours.

  Among the thermal tests, in the heating test, as shown in Table 1, the change in the plating surface was visually confirmed after heating to 300 ° C. in a heating furnace, and after 30 hours, it was cooled to room temperature by air cooling, and further the change in SnNi alloy plating Checked. In the thermal shock test, changes in the plating surface were visually confirmed after heating to 300 ° C. in a heating furnace, and after 30 hours, they were quenched in water at room temperature and further checked for changes in SnNi alloy plating.

  In the deformation test, after the heating test and thermal shock test, the ball was deformed by applying mechanical pressure by pressing the jig, and then the adhesion was confirmed by observing the large deformation part with a microscope. . Table 1 shows the results of the heating test, the thermal shock test, and the deformation test for the comparative product 5 and the test sample 4, respectively. In this table, no mark was found in the plated portion when visually confirmed.

  As shown in Table 1, the specimen 4 showed no significant abnormality in the plated part in any of the heating test, thermal shock test, and deformation test. On the other hand, although the comparative product 5 cleared the heating test, in the thermal shock test and the deformation test, cracks were observed in the plated portion, and the degree of deformation was also large.

  At this time, high adhesion of the SnNi alloy plating directly applied to the brass base was confirmed by surface observation after each test. Moreover, the whisker peculiar to Sn plating did not generate | occur | produce in SnNi alloy plating at all by the 300 degreeC and the heat test for 30 hours. Moreover, the surface of the SnNi alloy plating surface after the heating test was observed with a 70 × microscope. The photograph is shown in FIG. FIG. 11 (a) shows a case where Sn65% SnNi alloy plating is applied, and FIG. 11 (b) shows a case where Sn74% SnNi alloy plating is applied.

From the photographs in FIGS. 11 (a) and 11 (b), whiskers were not confirmed, but countless black micro dots were seen. In the case of pure Sn plating, it is considered that the Sn component in the SnNi alloy is diffused in the brass base while emitting the same black spot, and the Ni alloy is diffused by this diffusion. It was confirmed that the micro-throwing effect in which the Sn component and the copper alloy constituent metal element during plating were dissolved in each other layer contributed to the adhesion of the plating.
Due to this anchoring effect, peeling and cracking were not confirmed when the deformation test was carried out.

  As described above, as a result of conducting a thermal test and a deformation test on the test sample and the comparative product, the test product with NiCr alloy plating is superior in sliding property, sealing performance, and wear resistance to the comparative product. It was confirmed by experiment that there is sex.

(2) High Temperature Chlorine Water Durability Test Next, in order to confirm the chlorine resistance of the ball valve ball of the present invention, a high temperature chlorine water durability test is performed and the result is evaluated. As the specimen, the base is made of a copper base alloy, and the base is plated with SnNi alloy. The specimens 5 and 6 are SnNi alloy plated with a Sn content of 65%, and specimens 7 and 8 contain Sn. The ratio was SnNi alloy plating of 75%.
As test conditions, as shown in FIG. 12, the test products are connected in series to the test apparatus, and the valve openings are set in a half-open state. The test apparatus has a water temperature of 80 ° C. ± 2 ° C. and free residual chlorine concentration. A corrosion resistance test was performed by circulating 10 mg / L of high-temperature chlorine water.
The specimens were observed visually and by a stereomicroscope after 168 hours (7 days) and after 226 hours (14 days). Moreover, after this durability test, the plating thickness of the specimen was measured with an X-ray analysis microscope (Horiba Seisakusho XGT-5000WR).

FIG. 13 shows a photograph of the specimen using a stereomicroscope after the test. 13 (a) and 13 (b) show the state after 168 hours from the start of the corrosion resistance test of the specimens 5 and 6, respectively, and FIG. 13 (c) and FIG. 13 (d) show the specimen 5 respectively. , 6 shows the state after 336 hours have elapsed since the start of the corrosion resistance test. In any case, no peeling of the plating was observed.
13 (e) and 13 (f) show the state after 168 hours from the start of the corrosion resistance test of the specimens 7 and 8, and FIG. 13 (g) and FIG. 13 (h) show the specimen 7 , 8 shows a state after 336 hours have elapsed since the start of the corrosion resistance test. Also in these cases, peeling of the plating was not observed.

  As another comparative product, balls with CuSn plating applied to the substrate were used as comparative products 6 and 7, and the comparative products 6 and 7 were connected in series to the test apparatus shown in FIG. In this case, the comparative product 6 was CuSn plating with a Sn content ratio of 50%, and the comparative product 7 was CuSn plating with a Sn content ratio of 40%.

  FIG. 15 shows photographs of the comparative products 6 and 7 using a stereomicroscope after the test, and FIG. 15A shows a state 24 hours after the start of the test of the comparative product 6. FIG. 15B shows a state after 24 hours from the start of the test of the comparative product 7. In any case, since rust was seen on the primary side, the test was stopped 24 hours after the start of the test. In addition, when the comparative product 6 and the comparative product 7 are compared, the comparative product 5 is somewhat superior after 24 hours from the start of the test. This is because the comparative product 6 and the comparative product 7 are different from the test apparatus. Since it is also considered that the pipes were connected in 13 series states, it is difficult to determine the superiority of the comparative product 6 and the comparative product 7 based on a short test time of 24 hours later.

  As described above, as a result of performing the high temperature chlorine water durability test on the test sample and the comparative product, the test product subjected to NiCr alloy plating is more than the comparative product subjected to NiCr alloy plating and the comparative product subjected to CuSn plating. It was confirmed by this experiment that there is an advantage in chlorine resistance.

(3) Dezincification corrosion resistance test Next, in order to confirm the dezincification corrosion resistance of the ball valve ball of the present invention, a dezincification corrosion resistance test was conducted based on the ISO dezincification corrosion test. Evaluate the results. The conditions of this test are as follows. The specimen used for the test was designated as specimen 9, and as this specimen 9, SnNi alloy plating with a Sn content ratio of 65% was applied to a base made of C3771 formed into a solid ball shape by forging. Shall.

The test solution used for the corrosion test was a 1% CuCl ₂ (CuCl ₂ -2H ₂ O 12.7 to 12.8 g / L) solution. The exposure time was 24 hours, and the test temperature was 75 ° C. The exposed area of the sample 9 was 100 mm ² or more, and the surface was degreased with ethanol. As a test evaluation standard, the maximum dezincification corrosion depth was set to 200 μm or less. FIG. 16 shows a part of the sample 9 and the measurement position of the maximum dezincification corrosion depth. Of these, FIG. 16 (a) shows A part, B part and C part which are measurement points on the outer surface of the ball, and FIG. 16 (b) shows D part which is a measurement part on the inner peripheral surface of the ball back surface. E part and F part are shown. The measurement result of the maximum dezincing depth by this dezincification corrosion resistance test is shown in Table 2, and the photograph after the test of each measurement location in the specimen 9 is shown in FIG.

  From the results of Table 2 and the photograph of FIG. 17, no peeling of the SnNi alloy plating was observed in the ISO dezincification corrosion test. From this result, it was confirmed that a uniform plating layer having strong adhesion was obtained. Moreover, there was only one main dezincification corrosion location, the dezincification corrosion depth was also suppressed to 15 μm, and almost no corrosion was observed in the C3771 material as the base (substrate).

  In addition, in order to compare with the specimen, a dezincification corrosion resistance test was performed on a ball not subjected to SnNi alloy plating and a ball subjected to NiCr plating, respectively. The dezincification corrosion depth was 1000 to 1200 μm, and the maximum dezincification corrosion depth of the balls subjected to NiCr plating was 400 to 600 μm. Compared with this, since the maximum dezincification corrosion depth in the test sample 9 can be said to be almost 0, in the ISO dezincification corrosion test, there was no large plating peeling and dezincification corrosion was suppressed to the minimum. Thus, it was confirmed that it has excellent corrosion resistance. From this, it can be said that the specimen 9 has no fear that a chemical solution or the like penetrates into the substrate, and a dense plating is obtained.

Next, the results of a dezincification corrosion resistance test when leadless dezincification resistant brass is used as a base and SnNi alloy plating is applied to this base will be described. Conditions such as the test solution for the corrosion test, the exposure time, and the test temperature were in accordance with the above dezincification corrosion resistance test. Further, a part of the specimen 10 in this test and the measurement position of the maximum dezincification corrosion depth are the same as described above, and this is shown in FIG. The substrate was a solid ball formed by forging using lead-free dezincing-resistant brass, and the specimen 10 was provided by applying SnNi alloy plating to the front and back surfaces of this ball. In addition, in order to compare with this test sample 10, the same lead-free dezincing-resistant brass is used as a base, and a heat treatment after forging and plating treatment is not added to this base as a comparative product 8.
The measurement results of the maximum dezincing depth by these dezincification corrosion resistance tests are shown in Table 3, a photograph of the test sample 10 after the test is shown in FIG. 18, and a photograph of the comparative product 8 after the test is shown in FIG.

  From the results shown in Table 3 and FIG. 18, the specimen 10 showed no peeling of SnNi alloy plating in the ISO dezincification corrosion test. From this result, it was confirmed that the adhesion was strong and a uniform plating layer was obtained. In addition, although dezincification corrosion of about 75 μm was confirmed in the center part (E part) on the back surface, no dezincification corrosion was confirmed in other parts, and it was confirmed that excellent corrosion resistance was exhibited.

  On the other hand, since the comparative product 8 was not heat-treated, selective dezincification corrosion of β phase of 40 to 50 μm is observed as shown in Table 3 and FIG. In the absence of such plating treatment, heat treatment is required to improve dezincification corrosion resistance.

From the results of the above dezincification corrosion resistance test, even if the substrate is formed of any material of C3771 or leadless dezincification resistance brass, large plating delamination was confirmed in the ISO dezincification corrosion test. In addition, only a slight corrosion was confirmed in the dezincification corrosion, and it was confirmed that it had excellent corrosion resistance.
Thereby, it was confirmed that the test sample in the present invention is superior in dezincification corrosion resistance than the comparative product.

  As described above, from the results of the steam durability test, thermal test (heating test, thermal shock test), high-temperature chlorine water durability test, and dezincification corrosion resistance test, the optimum plating film thickness of SnNi alloy plating is It has been confirmed that 0.5 μm <film thickness ≦ 3 μm is desirable, and at this plating film thickness, it exhibits excellent wear resistance while ensuring slidability and sealability, and is also resistant to chlorine and It was confirmed that the dezincification corrosivity can be improved. At this time, it was confirmed that the alloy ratio of the SnNi alloy plating is most preferably 65% ≦ Sn <75%.

DESCRIPTION OF SYMBOLS 1 Ball body 2 Base 3 Covering surface 4 Plating layer 21 Container 22 Rack (jig)
31 Body 31a Inlet 31b Outlet 32 Ball sheet 33 Stem W Plating solution

Claims (5)

  A ball valve ball characterized in that an SnNi alloy plating layer of 0.5 μm <film thickness ≦ 3 μm is provided on a coated surface of a base of a ball valve body made of copper or copper alloy.   The ball valve ball excellent in chlorine resistance and dezincification corrosion resistance according to claim 1, wherein the film thickness is 2 μm <film thickness ≦ 3 μm.   The ball for ball valve excellent in chlorine resistance and dezincification corrosion resistance according to claim 1 or 2, wherein an alloy ratio of the SnNi alloy plating is 65%? Sn <75%.   The ball valve body is attached to a jig, the ball valve body is immersed in a container containing SnNi alloy plating treatment liquid, and then the ball valve body and the plating treatment liquid are energized to energize the base of the ball valve body. The ball valve ball plating method according to any one of claims 1 to 3, wherein an SnNi alloy plating process is performed on the coated surface of the ball valve.   5. The ball valve body according to claim 1, wherein a ball valve body that has been subjected to SnNi alloy plating is incorporated in a body having an inlet and an outlet through a ball seat, and the ball valve body is attached to a stem. A ball valve characterized by being provided to be freely rotatable via

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