JP7707093B2 - Faucet parts - Google Patents

Description

The present invention relates to a water faucet component. More specifically, it relates to a water faucet component intended for use in environments where corrosion resistance due to moisture is required.

Patent Document 1 discloses a technology for improving the stain-resistant properties of wet-area components used in indoor wet environments. Specifically, a DLC (diamond-like carbon) coating is formed on the surface of the substrate of the wet-area component. The DLC coating contains more than a specified amount of hydrogen atoms and has a density smaller than a specified value, thereby enhancing both the stain-resistant properties and the stain-resistant durability.

Patent No. 6641596

In the technology described in Patent Document 1, the density of the DLC coating is low, so there is a concern that moisture on the coating surface will penetrate into the coating, causing potential corrosion between the coating and the base material, which may lead to coating peeling. As a countermeasure to this, it is possible to thicken the DLC coating, but since high residual stress is generated in the DLC coating during deposition, thickening the coating is not preferable as it actually makes the coating more susceptible to peeling. Therefore, the present invention provides a water faucet component that can appropriately increase corrosion resistance due to moisture.

In order to solve the above problems, the faucet member of the present invention takes the following measures. That is, the first invention of the present invention is a faucet member having a base material body made of a copper alloy, a metallic intermediate layer formed in a laminated manner over the entire area of a specified surface of the base material body, and a DLC coating layer classified as ta-C formed in a laminated manner over the entire area of the surface of the intermediate layer, and the faucet member has a layered work-hardened portion formed over the entire area of the specified surface of the base material body, the hardening of which is higher than the hardness of other parts of the base material body due to work-hardening caused by pressure molding.

Here, DLC is generally known as amorphous carbon containing the SP-3 structure. DLC is classified into four types based on its SP-2 bond-SP-3 bond ratio and hydrogen content: ta-C (tetrahedral amorphous carbon), a-C (amorphous carbon), ta-C:H (hydrogenated tetrahedral amorphous carbon), and a-C:H (hydrogenated amorphous carbon). Of these, ta-C has the highest ratio of SP-3 structure among DLCs, and is known to have the highest density and hardness. ta-C also has excellent appearance retention properties such as wear resistance, insulation, heat resistance, and chemical non-reactivity.

According to the first invention, a high-density DLC coating layer classified as ta-C is formed on a specified surface of the base material body via a metallic intermediate layer, thereby appropriately preventing moisture penetration from the surface of the water faucet member. Specifically, a work-hardened portion is formed by pressure molding over the entire area of the specified surface on which the DLC coating layer of the base material body is formed, and although the detailed mechanism is unknown, an intermediate layer for ensuring adhesion and a DLC coating layer that serves as a corrosion-resistant coating can be appropriately formed on the specified surface. This makes it possible to appropriately increase the moisture corrosion resistance of the water faucet member. Note that examples of pressure molding methods for forming a work-hardened portion over the entire area of the specified surface of the base material body include blasting and barrel processing.

The second invention of the present invention is a water faucet member according to the first invention, in which the predetermined surface of the base material body on which the work-hardened portion is formed is a rough surface having numerous fine irregularities with a depth of 1 μm or more, and/or the Vickers hardness at a depth position within 5 μm from the predetermined surface of the base material body is 5 Hv or more. The hardness of the predetermined surface of the base material body is measured by the nanoindentation method, and the measured value is converted to Vickers hardness.

According to the second invention, the work-hardened portion formed as described above allows the intermediate layer and DLC coating layer to be more appropriately formed on the specified surface of the base material body.

The third invention of the present invention is a faucet component according to the first or second invention, in which the base material body contains 50% or more copper, with the remainder being a copper alloy made of lead, zinc, tin, iron, nickel, and antimony.

According to the third invention, the moisture corrosion resistance of the base material body made of a copper alloy of the above composition can be appropriately improved by the DLC coating layer.

1 is a plan view showing a schematic diagram of a water faucet member according to an embodiment of the present invention. FIG. 2 is a cross-sectional view that illustrates a cross-sectional structure of a water faucet member. 4 is a process diagram showing a method of manufacturing a faucet member.

Below, the form for implementing the present invention is explained with reference to the drawings.

(Water faucet member 1)
First, the configuration of a faucet member 1 according to an embodiment of the present invention will be described. As shown in Fig. 1, the faucet member 1 according to this embodiment is configured as a main body member of a faucet fitting used in an indoor wet environment. The faucet member 1 may also be a pipe of a faucet fitting. As shown in Fig. 2, the faucet member 1 comprises a copper alloy base material body 2, a metallic intermediate layer 3 coated on the entire surface of the base material body 2, and a DLC coating layer 4 coated on the entire surface of the intermediate layer 3.

The base material body 2 is made of a copper alloy containing copper as a main component. Specifically, the base material body 2 is made of a copper alloy containing 50% or more copper, with the remainder being made of lead, zinc, tin, iron, nickel, and antimony. The base material body 2 may be made of pure copper, brass, bronze, cupronickel, or nickel silver. The specific shape of the base material body 2 is not particularly limited, and may be a tubular shape such as a circular tube or a square tube, a columnar shape such as a cylinder or a rectangular column, a spherical shape, or a box shape or a plate shape.

As shown in FIG. 3, the base material body 2 is cut after casting to form a predetermined shape, and then the entire surface is buffed to a predetermined surface roughness (pre-process S1). The base material body 2 then undergoes a lead removal process S2 and is then subjected to a pressure molding process S3. In the pressure molding process S3, the entire surface of the base material body 2 is subjected to a blasting process or a barreling process, and a rough surface 2A with countless fine irregularities is formed on the entire surface of the base material body 2 (see FIG. 2). In addition, in this pressure molding process S3, a layered work-hardened portion H, which has a higher hardness than the back surface region (other parts), is formed on the entire surface region of the base material body 2, including the rough surface 2A, due to the peening action associated with the blasting process or the barreling process.

Then, the base material body 2 is subjected to a mirror finishing process S4, where the entire rough surface 2A is polished to a mirror-like finish while retaining the uneven shape. The base material body 2 is then subjected to a cleaning process S5, where dirt adhering to the surface is removed and the base material body 2 is cleaned. The base material body 2 is then subjected to an intermediate layer deposition process S6, where a metallic intermediate layer 3 is deposited on the surface. The base material body 2 is then subjected to a DLC coating layer deposition process S7, where a DLC coating layer 4 classified as ta-C is further deposited on the surface of the intermediate layer 3 thus deposited. Each process is described in detail below.

(Pressure molding step S3)
In the pressure molding step S3, the surface of the base material body 2 is subjected to blasting or barreling to form a rough surface 2A consisting of an uneven shape with a concave depth of 1 μm or more, a maximum height of 5 to 100 μm, an average interval between the concaves and convexes of 10 to 500 μm, and a number of concaves and convexes of ¹⁰ to 100/mm2 on the entire surface of the base material body 2. If it is desired to form the rough surface 2A only in a partial area of the surface of the base material body 2, a masking material made of a resin or rubber sheet (not shown) may be attached to the other areas and then blasting or barreling may be performed. This allows the rough surface 2A to be formed only in the surface area of the base material body 2 other than the area where the masking material is attached.

By using blasting or barreling, it is possible to form a rough surface 2A with countless fine irregularities across the entire surface, even if the base material body 2 has a complex surface shape. Examples of blasting devices used in blasting include air blasting devices (compressor type, blower type, etc.) that use air to project media (abrasive material), and shot blasting devices that throw media by rotating a motor.

The depth and surface roughness of the rough surface 2A formed by blasting can be appropriately controlled by adjusting the particle size, shape, material, projection pressure, projection density, projection time, etc. of the media. Examples of media materials include zirconium, alumina (white, brown), silicon carbide (green, black), silica sand, iron, copper, stainless steel, zinc, aluminum, garnet, resin, glass, etc. The media may also be made of an elastic base material coated with fine abrasive grains.

Examples of the shape of the media include spherical or acute-angled shapes. Examples of the particle size of the media include 5 μm to 2 mm. The projection pressure of the media is preferably 0.1 to 0.5 MPa. From the viewpoint of finishing the rough surface 2A to an appropriate surface roughness, it is particularly preferable to perform the blasting process using media made of zirconium with a particle size of 600 μm, projecting it onto the rough surface 2A at a projection pressure of 0.3 MPa for 15 seconds.

Barrel processing is a processing method in which the base material body 2, media (abrasive material), and compound (solution) are placed in a tank and stirred together, and the friction creates a rough surface 2A with the same uneven shape as described above on the surface of the base material body 2.

The equipment used for barrel processing includes fluidized, rotary, centrifugal, and vibration types, depending on the method of stirring inside the tank. The depth and surface roughness of the rough surface 2A formed by barrel processing can be appropriately controlled by adjusting the particle size, shape, material, input amount, processing time, etc. of the media. It can also be appropriately adjusted depending on the type of barrel processing equipment.

(Mirror finish processing step S4)
In the mirror finish process S4, the entire surface (rough surface 2A) of the base material body 2 is subjected to blasting or barrel processing using media with a smaller particle size, to finish the entire surface of the base material body 2 in a mirror-like polished state. This mirror finish process removes fine scratches that have been caused on the surface of the base material body 2 by the previous buffing and pressure forming (blasting or barrel processing).

In the mirror finish process S4, the entire surface (rough surface 2A) of the base material body 2 is ground to a uniform depth of 2 μm or less. Therefore, even if the entire rough surface 2A is mirror-finished after the rough surface 2A is formed on the base material body 2 by the previous pressure molding process S3, the uneven pattern of the rough surface 2A will not disappear.

The surface roughness of the base material body 2 that is finished by the mirror finish process can be appropriately controlled by changing the processing conditions such as the type and shape of the media, as in the pressure molding process S3. From the viewpoint of finishing the rough surface 2A of the base material body 2 to an appropriate surface roughness, it is particularly preferable to perform the mirror finish process by blasting the rough surface 2A with media carrying abrasive grains of SDC: metal-coated synthetic diamond with a grain size of 1 μm around the base material with a grain size of 0.5 mm at a projection pressure of 0.2 MPa for 5 to 15 minutes.

In more detail, if the base material body 2 is made of bronze, the media should be projected for 5 to 15 minutes, and if the base material body 2 is made of brass, the media should be projected for 8 to 15 minutes. By performing the mirror finish processing step S4 using the above method, it is possible to achieve a mirror finish while suppressing the temperature rise of the base material body 2, and this is suitable as a processing step to be performed before forming the intermediate layer 3 and DLC coating layer 4.

(Cleaning process S5)
In the cleaning process S5, a cleaning method using a hydrocarbon-based cleaning liquid is used to remove dirt adhering to the surface (rough surface 2A) of the base material body 2. Note that the cleaning process S5 may be a process of cleaning the surface of the base material body 2 by a cleaning method using an aqueous cleaning liquid, a semi-aqueous cleaning liquid, or a chlorine-, bromine-, or fluorine-based solvent-based cleaning liquid.

In the cleaning process S5, first, a rough cleaning process is performed in which abrasives adhering to the surface of the base material body 2 are removed by water cleaning. Next, the main cleaning process is performed in which the surface of the base material body 2 is cleaned by emulsion cleaning. This emulsion cleaning process combines an ultrasonic cleaning method in which water is vibrated by ultrasonic waves, and a vacuum cleaning method in which the inside of the cleaning tank is repeatedly depressurized and pressurized to a near vacuum state.

By combining emulsion cleaning with ultrasonic cleaning, it is possible to effectively clean dirt adhering to the base material body 2. Furthermore, by combining emulsion cleaning with vacuum cleaning, it is possible to make the cleaning liquid reach the inside of blind holes and pocket holes that cannot be cleaned under atmospheric pressure, and effectively clean even the small gaps in the base material body 2. In particular, by combining vacuum cleaning and ultrasonic cleaning, the effect of ultrasonic waves is enhanced compared to atmospheric pressure, making it possible to perform more effective cleaning. In addition to or instead of the above cleaning methods, emulsion cleaning may be combined with a degassing cleaning method, a rotating cleaning method, a swinging cleaning method, or a shower cleaning method.

Combining the degassing cleaning method can further increase the effectiveness of ultrasonic waves when using the ultrasonic cleaning method. Combining the rotational cleaning method and the oscillating cleaning method can physically create a flow of cleaning liquid, further increasing the cleaning effect. In addition, ultrasonic waves can be more easily applied evenly to the surface of the base material body 2. Other methods for physically creating a flow of cleaning liquid include circulating water and bubbling it. In addition, combining the shower cleaning method makes it possible to spray the cleaning liquid on the base material body 2 not only from above, but also from the sides and below, allowing for appropriate cleaning. Other cleaning methods include high-pressure jet cleaning, spray cleaning, and brush cleaning.

By the above cleaning, dirt such as oil adhering to the surface of the base material body 2 dissolves in the cleaning liquid and is dispersed throughout the cleaning liquid. Also, dirt adhering to the base material body 2 dissolves in the cleaning liquid and is replaced by the cleaning liquid. Next, in the cleaning process step S5, a process of vapor cleaning the surface of the base material body 2 is performed as a rinsing cleaning. In vapor cleaning, the cleaning liquid is boiled and the cleaning liquid is used to clean dirt remaining on the surface of the base material body 2 with even greater precision.

Next, in the cleaning process S5, a drying process is performed to dry the cleaning liquid remaining on the surface of the base material body 2. This drying process is performed by so-called vacuum drying. Vacuum drying is a known method in which the pressure inside the cleaning tank is reduced to near vacuum, rapidly lowering the boiling point of the cleaning liquid and drying the cleaning liquid by bumping. By using vacuum drying, the bumping drying of the cleaning liquid can be effectively promoted by reducing the pressure inside the cleaning tank, which has been heated by the previous vapor cleaning, and the drying process can be performed appropriately so as not to leave stains on the base material body 2.

The drying process may be performed by hot air drying or suction drying. Hot air drying is a known method of drying the surface of the base material body 2 by sending hot air into the inside of the cleaning tank. Suction drying is a known method of drying the surface of the base material body 2 by sending compressed hot air into the inside of the cleaning tank and simultaneously drawing it out from the other side with a suction blower. Hot air drying and suction drying can also be applied to cleaning tanks that use aqueous cleaning liquids in which vacuum drying is not possible.

(Intermediate layer film formation step S6)
In the intermediate layer forming step S6, a metallic intermediate layer 3 is formed directly on the entire surface (rough surface 2A) of the base material body 2. The intermediate layer 3 is interposed between the base material body 2 and the DLC coating layer 4, and functions as a layer for improving the adhesion between them. For the intermediate layer 3, at least one metal selected from the group consisting of nickel, titanium, chromium, tungsten, and silicon can be used.

The intermediate layer 3 may be a single-layer structure made of one metal selected from the above group, or may be a laminate structure made of two or more metals. It is particularly preferable that the intermediate layer 3 be made of titanium, which has excellent adhesion to the base material body 2 and the DLC coating layer 4 and is also highly corrosion-resistant.

In the intermediate layer deposition process S6, the intermediate layer 3 is deposited in a laminated form on the surface (rough surface 2A) of the base material body 2 by a sputtering method classified as a PVD method (physical vapor deposition method). In the intermediate layer deposition process S6, first, an ion bombardment process is performed using argon ions to remove passivation films such as oxide films and hydroxide films that are present on the surface of the base material body 2.

Next, by sputtering, a negative voltage is applied to the cathode target (film-forming material) in a vacuum containing an inert gas (argon gas) to generate a glow discharge, and the gas ions collide with the film-forming material to knock out particles of the film-forming material, which are then attached and deposited on the surface (rough surface 2A) of the base material body 2 to form a dense thin film. By forming the intermediate layer 3 by sputtering, a dense, highly adhesive thin film of uniform thickness can be formed on the surface of the base material body 2 without exposing the base material body 2 to liquid or high-temperature gas.

In addition, the intermediate layer deposition process S6 may be a process of depositing the intermediate layer 3 on the surface (rough surface 2A) of the base material body 2 by the arc ion plating method, in addition to the sputtering method. The arc ion plating method is a known method in which the deposition material is evaporated in a vacuum, and the positively charged deposition material ionized (ionized) by arc discharge is attracted to the surface of the base material body 2 to which a negative charge has been applied, to deposit the film.

(DLC coating layer deposition process S7)
In the DLC coating layer forming step S7, a DLC coating layer 4 classified as ta-C is directly formed on the surface of the intermediate layer 3 formed on the surface (rough surface 2A) of the base material body 2. Specifically, in the DLC coating layer forming step S7, a DLC coating layer 4 having a uniform thickness is formed in a laminated form on the surface of the intermediate layer 3 by a vacuum arc deposition method classified as a PVD method (physical vapor deposition method). The DLC coating layer 4 is formed by the vacuum arc deposition method as a coating classified as ta-C, which has the highest ratio of SP-3 structure among DLCs (diamond-like carbons) and is characterized by the highest density and hardness. ta-C is amorphous carbon with a ratio of SP-3 structure of 50% to 90% and a hydrogen content of 5 mass% or less.

More specifically, the DLC coating layer 4 is formed by the well-known FCVA method (filtered cathodic vacuum arc method), which is known as a method among vacuum arc deposition methods that can form a film with particularly few surface defects. The FCVA method is a well-known method that, when depositing a ta-C coating on a workpiece by vacuum arc deposition, filters out droplets (macroparticles with an SP-2 structure or a composition structure similar thereto), which are electrically neutral evaporated particles that can be emitted from solid graphite, which is the evaporation source of the cathode target, from the plasma during plasma transport, making it difficult for them to adhere to the coating.

By making it difficult for droplets to adhere to the coating, the coating surface can be formed in a shape that ensures geometric uniformity (flatness) and chemical uniformity with few irregularities. As a result, the DLC coating layer 4 can be formed in a shape that has a smooth surface and is less susceptible to deterioration of mechanical properties. The DLC coating layer 4 is preferably formed using the above-mentioned FCVA method so that the surface defects are 20% or less. In addition, the DLC coating layer 4 is preferably formed to a thickness of 0.5 to 5.0 μm and a Vickers hardness of the coating of 1,500 to 5,000 Hv. When the thickness of the coating is several tens of nm to several tens of μm, the hardness of the coating may be indicated by nanoindentation hardness.

The DLC coating layer 4 is provided on the surface (rough surface 2A) of the base material body 2 with the intermediate layer 3 interposed therebetween, so that the DLC coating layer 4 is formed on the surface of the base material body 2 with good adhesion. As shown in FIG. 2, the DLC coating layer 4 forms a rough surface on the surface of the faucet member 1 that is dense, hard, and highly wear-resistant, with countless fine irregularities depending on the uneven shape of the rough surface 2A of the base material body 2. The DLC coating layer 4 and the intermediate layer 3 formed below it are each formed in a layered form with a uniform thickness on the rough surface 2A of the base material body 2 by the above-mentioned vacuum arc deposition method or sputtering method. Therefore, a rough surface with a clearly defined uneven pattern can be formed on the surface of the faucet member 1, even if the concave shape of the rough surface 2A that is recessed into the base material body 2 is not set deep.

The intermediate layer 3 and DLC coating layer 4 are configured to be formed on the layered work-hardened portion H that has been work-hardened by the peening action caused by pressure molding (blasting or barrel processing) of the base material body 2. For this reason, the intermediate layer 3 and DLC coating layer 4 are configured to be appropriately formed on the work-hardened portion H without causing any major molding defects, although the detailed mechanism is unknown. One of the reasons for this is presumed to be the following.

In other words, it is presumed that the peening effect of pressure forming (blasting or barreling) of the base material body 2 crushes concave casting defects such as voids remaining on the surface (rough surface 2A) of the base material body 2, and the intermediate layer 3 is formed evenly and uniformly on the surface of the base material body 2. By forming the intermediate layer 3 evenly on the surface of the base material body 2, the DLC coating layer 4 formed on that surface is also formed appropriately, and a highly corrosion-resistant coating can be formed on the surface of the base material body 2.

This allows the water faucet member 1 to have an appropriate increase in corrosion resistance against moisture. The corrosion resistance of the water faucet member 1 can be evaluated by the CASS test method (salt spray test method) specified in JIS Z2371. The base material body 2 is configured such that a work-hardened portion H is formed on the surface by the pressure molding (blast processing or barrel processing) described above, and the Vickers hardness at a depth position within 5 μm from the surface is 5 Hv or more. The hardness of the base material body 2 is measured by the nanoindentation method, and the measured value is converted to Vickers hardness.

Other embodiments
Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration shown in the above embodiment, and various modifications, additions, and deletions are possible within the scope of the present invention. For example, the faucet member of the present invention may be any member intended for use in an environment requiring corrosion resistance due to moisture, and may be applied to members other than the main body members and piping of faucets, such as handles of faucets used in indoor and outdoor wet environments.

Reference Signs List 1: Faucet member 2: Base material body 2A: Rough surface 3: Intermediate layer 4: DLC coating layer S1: Pre-process S2: Lead removal process S3: Pressure molding process S4: Mirror finish process S5: Cleaning process S6: Intermediate layer deposition process S7: DLC coating layer deposition process H: Work-hardened portion

Claims (3)

A water faucet member,
The present invention has a base material body made of a copper alloy, a metal intermediate layer formed in a laminated state on the entire surface of a predetermined surface of the base material body, and a DLC coating layer classified as ta-C formed in a laminated state on the entire surface of the intermediate layer,
A faucet component in which a layered work-hardened portion having a higher hardness than other parts of the base material body is formed over the entire area of the specified surface of the base material body due to work-hardening caused by pressure molding. The faucet member according to claim 1, wherein the predetermined surface of the base material body on which the work-hardened portion is formed is a rough surface having numerous minute irregularities with a depth of 1 μm or more, and/or the Vickers hardness at a depth position within 5 μm from the predetermined surface of the base material body is 5 Hv or more. The faucet member according to claim 1 or 2, wherein the base material body is a copper alloy containing 50% or more copper, with the remainder being made of lead, zinc, tin, iron, nickel, and antimony.

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