Alloy member, equipment, and method of producing alloy member

Abstract

To provide an alloy member having both corrosion resistance and excellent appearance.SOLUTION: An alloy member 100 comprises a substrate 101 comprising magnesium as a main component and containing lithium, and a corrosion preventive film 102 containing magnesium, phosphorus, and fluorine, the corrosion preventive film 102 being disposed on the substrate 101. The average film thickness T of the corrosion preventive film 102 is 20 μm or more, and the difference between the maximum value and the minimum value of the film thickness of the corrosion preventive film 102 is less than 20 μm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to alloy components, devices, and methods for manufacturing alloy components. [Background technology]

[0002] Magnesium-lithium alloys, which are mainly composed of magnesium and contain lithium, are used in various articles because they are lightweight and have excellent mechanical strength. However, lithium is an element that is very active, easily ionized, and easily reacts with water, so that magnesium-lithium alloys tend to corrode, for example, in a wet state. For this reason, there is a demand for improving the corrosion resistance of magnesium-lithium alloys. Patent Document 1 discloses that the surface of a magnesium-lithium alloy is subjected to a chemical conversion treatment using a treatment liquid containing fluorine and aluminum. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-171776 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the anticorrosive film of magnesium-lithium alloy obtained by the method described in Patent Document 1 is produced by chemical conversion treatment, and therefore the film thickness cannot be made sufficiently thick. Therefore, although the appearance is good, there is a risk of corrosion if exposed to a high-temperature and high-humidity environment for a long period of time. [Means for solving the problem]

[0005] A first aspect for solving the above problem is an alloy component comprising a substrate containing magnesium as a main component and lithium, and an anticorrosion coating formed on the substrate and containing magnesium, phosphorus and fluorine, wherein the average thickness T of the anticorrosion coating is 20 μm or more, and the difference between the maximum and minimum thicknesses of the anticorrosion coating is less than 20 μm.

[0006] A second aspect for solving the above problem is a method for producing an alloy member, comprising the steps of placing an anode and a cathode in an electrolytic solution, and applying a voltage between the anode and the cathode to form an anticorrosion film on the anode, wherein the anode contains magnesium as a main component and lithium, the electrolytic solution contains fluoride ions, ammonium ions, and phosphate ions, and the concentration of the ammonium ions in the electrolytic solution is in the range of 5.7 mol / L or more and 11 mol / L or less. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an alloy member that achieves both corrosion resistance and good appearance, and a method for manufacturing the same. [Brief description of the drawings]

[0008] [Figure 1] Schematic cross-sectional view of an alloy member according to a first embodiment. [Diagram 2] FIG. 1 is a plan view of an alloy member according to a first embodiment; [Diagram 3] Schematic plan view of an alloy member according to a comparative example [Figure 4] FIG. 1 is a flow diagram showing a manufacturing process of an alloy member according to a first embodiment. [Diagram 5] Schematic diagram of an anodizing apparatus for manufacturing an alloy member according to the first embodiment. [Figure 6] FIG. 1 is a diagram showing an embodiment of a current-voltage curve when forming an anticorrosion film. [Figure 7] Schematic diagram of an imaging device according to a second embodiment. [Figure 8] FIG. 13 is a schematic diagram of an electronic device according to a third embodiment. [Figure 9] 13 is a schematic diagram of a moving body according to a fourth embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment [Alloy parts] FIG. 1 is a schematic diagram of an alloy member according to a first embodiment, and is a cross-sectional view taken along the lamination direction.

[0010] The alloy member 100 includes a substrate 101 and an anticorrosive film 102 provided on the substrate 101. The use of the alloy member of this embodiment is not particularly limited, and it can be used, for example, as a structural material such as an exterior member, an interior member, and a sliding member of a device having parts. Note that a coating film such as a primer or a topcoat layer may be provided on the anticorrosive film 102 depending on the application. An example of the coating film is a heat-shielding film having a heat-shielding function.

[0011] (base material) The base material 101 is made of a magnesium-lithium alloy (hereinafter, Mg-Li alloy) containing magnesium as a main component and lithium. In this specification, the main component means, when the base material is made of a plurality of elements, the element that contains the largest total mass among the elements. Alternatively, when the base material is made of a plurality of compounds, the compound that contains the largest total mass among the compounds.

[0012] Among Mg-Li alloys, the sum of the magnesium and lithium contents is preferably 90% by mass or more for use as the substrate 101. When the sum of the magnesium content and the lithium content is 90% by mass or more, the alloy is lighter than magnesium alloys that do not contain lithium. Mg-Li alloys are lightweight metal materials, and are superior in vibration-damping properties and specific strength compared to magnesium alloys that do not contain lithium. Superior vibration-damping properties refer to the ability to quickly convert vibration energy into thermal energy, thereby quickly converging vibration. Specific strength is the tensile strength per density, and the higher the specific strength, the lighter the member can be.

[0013] The Mg-Li alloy may contain aluminum, zirconium, and / or germanium in addition to magnesium and lithium. In addition to the above elements, the Mg-Li alloy may contain at least one element selected from the group consisting of zinc, calcium, silicon, and manganese, with the balance being inevitable impurities and magnesium. The inevitable impurities are, for example, iron, cobalt, and nickel.

[0014] The lithium content in the Mg-Li alloy is preferably in the range of 0.5% by mass to 15% by mass. If it is less than 0.5% by mass, it cannot be made lighter than the magnesium alloy, and if it is more than 15% by mass, vibration damping properties may be insufficient. It is preferably 8% by mass to 14% by mass. More preferably, it is 5% by mass to 11% by mass, which is the range in which the α phase and the β phase coexist. Within this range, the corrosion resistance of the substrate 101 is high.

[0015] The aluminum (Al) content in the Mg-Li alloy is preferably in the range of 1% by mass to 8% by mass. In the alloy of the present disclosure, Al plays a role in increasing the fracture strength of the alloy. Therefore, when the Al content is in the above range, the alloy of the present disclosure can have sufficient mechanical strength compared to when it does not contain Al. It is believed that this is because Al and Mg react with each other and MgAl2, which is a compound of these, is precipitated, thereby increasing the mechanical strength. A more preferable content is in the range of 4% by mass to 7% by mass.

[0016] The total content of germanium (Ge) and beryllium (Be) in the Mg-Li alloy is in the range of 0.02% by mass or more and 0.4% by mass or less. In the alloy of the present disclosure, Ge and Be play a role of enhancing corrosion resistance by partially replacing Al. As described above, the mechanical strength of the Mg-Li alloy containing Al is increased by the reaction between Al and Mg, but at that time, lithium-rich grain boundaries segregate in the parent phase, making it prone to corrosion. However, by partially replacing Al with an element such as Ge or Be having a smaller atomic radius than Al, Ge or Be is actively arranged in the grain boundaries instead of Li, and the segregation of Li to the grain boundaries can be suppressed. Therefore, the corrosion resistance can be improved. The content of Ge alone is preferably in the range of 0.01% by mass to 0.4% by mass or less. More preferably, it is preferably in the range of 0.01% by mass to 0.2% by mass or less. In addition, the content of Be alone is preferably in the range of 0.02% by mass to 0.1% by mass or less. It is more preferable that the content is in the range of 0.01% by mass to 0.05% by mass.

[0017] The zirconium (Zr) content in the Mg-Li alloy is preferably in the range of 0.6 mass % to 3.0 mass % because this can prevent the grain size of the base material 101 from becoming coarse.

[0018] Zinc (Zn), calcium (Ca), silicon (Si) and manganese (Mn) in the Mg-Li alloy can increase the strength of the substrate 101. The sum of the contents of these elements is preferably in the range of 0.01% by mass or more and 5% by mass or less. Zn is preferably contained at 3% by mass or less, more preferably 0.2% by mass or more and 3% by mass or less. Mn is preferably contained at 0.3% by mass or less, more preferably 0.1% by mass or more and 0.3% by mass or less. Si is preferably contained at 0.2% by mass or less, more preferably 0.1% by mass or more and 0.2% by mass or less. Ca is preferably contained at 1.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less.

[0019] The raw material of the Mg-Li alloy is not particularly limited. Commercially available materials include LZ91, LAZ771, and Ares manufactured by Anritsu Materials Technology Co., Ltd.

[0020] The thickness of the base material 101 is not particularly limited, but from the viewpoint of ensuring sufficient rigidity, it is preferably thicker than the anticorrosive film 102 .

[0021] (Anti-corrosion film) The anticorrosion coating 102 is provided on the substrate 101. The anticorrosion coating 102 contains magnesium (Mg), phosphorus (P), fluorine (F), and oxygen (O), and preferably contains lithium (Li). Since the average thickness T of the anticorrosion coating 102 is 20 μm or more, the alloy member 100 of the present disclosure has excellent corrosion resistance. This makes it possible to prevent water from diffusing and reaching the interface between the anticorrosion coating 102 and the substrate 101 for a long period of time. Therefore, even if water seeps in from the surface of the anticorrosion coating 102, the possibility of the water reaching the substrate 101 can be reduced.

[0022] In addition, since the difference between the maximum and minimum film thicknesses is less than 20 μm, the alloy member 100 of the present disclosure also has an excellent appearance. More preferably, when the average film thickness T is in the range of 20 μm or more and less than 45 μm, the difference between the maximum and minimum film thicknesses is less than 15 μm, and even more preferably less than 10 μm. In addition, when the average film thickness T is in the range of 45 μm or more and 75 μm or less, the difference between the maximum and minimum film thicknesses is less than 19.5 μm.

[0023] On the other hand, the anticorrosion film obtained by the method described in Patent Document 1 is produced by chemical conversion treatment and is therefore thought to have a maximum thickness of about 10 μm. As a result of intensive research by the present inventors, it was found that an anticorrosion film with a thickness of about 10 μm can withstand durability tests such as short-term salt spray, but it is difficult to suppress corrosion in a high-temperature, high-humidity environment, for example, at a temperature of 60°C and a humidity of 85%. This is because when water adheres to the surface of an Mg-Li alloy, lithium reacts with water to produce lithium hydroxide (LiOH), which in turn generates hydrogen gas. When hydrogen gas is generated, the coating film of the alloy member may swell or peel off. Even if the coating film does not peel off, it may swell, causing a poor appearance.

[0024] Therefore, the inventors of the present application discovered that by forming a corrosion-resistant film 102 by performing anodizing treatment under specified conditions, it is possible to provide an alloy component that combines corrosion resistance with a good appearance by making the average film thickness T large and reducing the difference between the maximum and minimum film thicknesses to less than 20 μm.

[0025] 2 is a schematic diagram of the surface of the alloy member according to the first embodiment. The difference between the maximum and minimum film thickness of the anticorrosion coating 102 is less than 20 μm, and the entire surface 1021 can be seen as white. This means that the anticorrosion coating 102 has a substantially uniform thickness over its entire surface.

[0026] 3 is a schematic diagram of the surface of an alloy member of a comparative example. The difference between the maximum and minimum thicknesses of the anticorrosion coating 102X is 20 μm or more, and the surface 1021X has white parts and gray parts 1022A, 1022B, and 1022C that appear gray. Since the gray parts 1022A, 1022B, and 1022C have a smaller thickness than the other white parts, the color of the Mg-Li alloy substrate is visible through these parts and they appear gray. Therefore, if the surface 1021X of the anticorrosion coating 102X has a mixture of white parts and gray parts, it cannot be said that the appearance is good.

[0027] The phosphorus concentration P1 in the region 102B of the anticorrosion coating 102 close to the substrate 101 up to a thickness T / 2 is preferably lower than the phosphorus concentration P2 in the region 102A of the anticorrosion coating 102 far from the substrate 101 up to a thickness T / 2. The concentration means the amount of an element present per unit area. It is presumed that phosphorus exists as a magnesium phosphate-based compound in the anticorrosion coating 102. If magnesium phosphate is present in a large amount in the region 102B including the vicinity of the interface between the substrate 101 and the anticorrosion coating 102 with respect to the substrate 101 containing lithium, oxygen contained in the magnesium phosphate may react with lithium contained in the substrate to form lithium oxide (Li2O). This lithium oxide may react with water and thus deteriorate the durability of the alloy member in a high-temperature and high-humidity environment.

[0028] The fluorine concentration F1 in the region 102B up to a thickness T / 2 on the side of the anticorrosion coating 102 close to the substrate 101 is preferably higher than the fluorine concentration F2 in the region 102A up to a thickness T / 2 on the side of the anticorrosion coating 102 far from the substrate 101. This means that the region 102B has a higher content of inorganic fluoride and a lower content of inorganic oxide than the region 102A. If inorganic oxide is present in a large amount in the region 102B including the vicinity of the interface between the substrate 101 and the anticorrosion coating 102, oxygen and lithium may react to form lithium oxide. The type of inorganic fluoride is not particularly limited, but magnesium fluoride (MgF2), in which magnesium and fluorine can exist stably, is preferably present as a main component. If magnesium fluoride is present in a large amount in the region 102B including the vicinity of the interface between the substrate 101 and the anticorrosion coating 102, fluorine in magnesium fluoride may react with lithium to form lithium fluoride (LiF), which is stable against water. Therefore, the possibility of impairing durability is low. Therefore, it is preferable that the concentration of magnesium fluoride in region 102B is higher than that in region 102A.

[0029] In addition, in the anticorrosion coating 102, the fluorine content is preferably in the range of 9 atomic % or more and 66 atomic % or less. Similarly, the phosphorus content is preferably in the range of 2 atomic % or more and 26 atomic % or less. In addition, the magnesium content is preferably in the range of 14 atomic % or more and 38 atomic % or less. This is because the unevenness of the film thickness is less visible. This is for the following reasons. When the anticorrosion coating 102 has a large amount of fluorine, a film with good durability is obtained. However, since the film growth is not accompanied by dielectric breakdown, the film growth may stop at the point when a thin coating with high surface resistance is formed in a portion of the substrate surface where the lithium concentration is relatively low. At that time, the film growth continues in other portions of the substrate surface where the lithium concentration is relatively high, so that a difference in the thickness between a thin portion and a thick portion occurs, which may be visually recognized as an unevenness of the film. On the other hand, a film composition with a low amount of fluorine has a film composition mainly composed of magnesium phosphate. This is because the film growth of such a composition is accompanied by dielectric breakdown, and therefore the unevenness of the film is improved, but the durability may be deteriorated.

[0030] As described above, according to the present disclosure, since the average film thickness T of the anticorrosion coating 102 is 20 μm or more, the corrosion resistance is excellent even when an alloy containing magnesium as a main component and lithium is used for the base material 101. Furthermore, since the difference between the maximum and minimum film thicknesses of the anticorrosion coating 102 is less than 20 μm, the appearance is excellent even when an alloy containing magnesium as a main component and lithium is used for the base material 101. Therefore, according to the present disclosure, it is possible to provide an alloy member 100 that has both corrosion resistance and good appearance.

[0031] [Method of manufacturing alloy components] Next, a method for producing an alloy member according to the present disclosure will be described with reference to Fig. 4, Fig. 5, and Fig. 6. Fig. 4 is a flow diagram showing the steps for producing an alloy member. Fig. 4 is a schematic diagram of an anodizing apparatus for performing anodizing treatment.

[0032] First, an Mg-Li alloy is prepared as an anode. The manufacturing method of the anode is not particularly limited, but examples thereof include casting, thixoforming, and die-casting. The substrate obtained by rapidly cooling the molten metal has a tendency to have a different surface structure in the plane depending on the molded shape, the direction of the molten metal flow relative to the mold, the temperature difference, and the like. The in-plane distribution of this surface structure can be a factor in causing the thickness of the anticorrosion film to vary, so that the manufacturing method described below can provide an alloy member with excellent appearance even for such an anode.

[0033] Next, the anode and cathode are placed in the electrolytic solution. First, an electrolytic solution 401 to be used for anodization is prepared. The electrolytic solution is a liquid containing fluorine ions, ammonium ions, and phosphate ions. As a substance containing fluorine and / or ammonium, acidic ammonium fluoride, neutral ammonium fluoride, and ammonia can be used. As a substance containing phosphorus, for example, phosphoric acid and triammonium phosphate can be used.

[0034] The electrolyte is adjusted so that the concentration of ammonium ions in the solution is in the range of 5.7 mol / L to 11 mol / L. By setting the concentration of ammonium ions in this range, the reaction of the anticorrosion film can proceed at a lower voltage than when the concentration is outside this range. More specifically, since a low-resistance anticorrosion film can be formed from the initial growth stage, an anticorrosion film of uniform thickness can be obtained even if the film thickness is increased to 20 μm or more. On the other hand, if the concentration is outside this range, a high-resistance portion is formed from the initial growth stage of the anticorrosion film, and the potential difference within the film becomes non-uniform. Therefore, it becomes difficult to increase the film thickness above the high-resistance portion, which causes unevenness in the film thickness and poor appearance.

[0035] The electrolyte is preferably a solution containing fluoride ions and phosphate ions. The concentration of the fluoride ions is preferably in the range of 2.5 mol / L to 10.6 mol / L. The concentration of the phosphate ions is preferably in the range of 0.14 mol / L to 0.65 mol / L.

[0036] The anodizing device 400 that forms the anodic oxide film is composed of an outer tank 402 that holds and regulates the temperature of the electrolyte, and an inner tank 403 where the electrical reaction takes place. A temperature regulation mechanism 404 is installed in the outer tank 402, which keeps the temperature of the electrolyte constant. The temperature of the electrolyte can be set from a low temperature at which the components do not coagulate to a high temperature at which the components do not decompose. The optimum set temperature is about 25°C, which does not require much energy to regulate the temperature of the electrolyte. Although the device is described as being of a two-tank type, it is also possible to create a single-tank type.

[0037] The outer tank 402 and the inner tank 403 are connected by a magnet pump 405, and the liquid is circulated. In the formation of the anticorrosive film 102, liquid exchange on the Mg-Li alloy surface is important, but since the anodization reaction is an exothermic reaction, the electrolyte on the surface undergoes self-convection and active liquid exchange is performed. Therefore, the liquid circulation by the pump is more significant for removing by-products generated in the electrolyte than for liquid exchange on the surface. In the anodization of the Mg-Li alloy surface, the film is formed and at the same time, lithium in the anode is released into the liquid as ions. The released lithium ions react with fluorine ions and phosphate ions, which are components of the electrolyte, to generate poorly soluble salts. These poorly soluble salts may become cloudy by remaining in the liquid as fine particles. For this reason, a bag filter 406 is provided at the liquid outlet of the inner tank in order to remove fine particles generated in the liquid. It is preferable that the filter can remove fine particles of 10 μm or more. Furthermore, a filter may be installed in the piping system connected to the pump.

[0038] Next, an electric circuit capable of forming an anticorrosive film is formed. A carbon electrode 407 that functions as a cathode is installed in the inner tank 403. The material of this cathode is not particularly limited as long as it is a material that is stable and conductive in the electrolyte. For example, platinum, stainless steel, titanium, etc. can also be used.

[0039] Next, the anode 408 made of Mg-Li alloy is sandwiched and set in the electrical continuity holding jig 409. A natural oxide film is formed on the surface of the anode 408, but it does not need to be removed beforehand because it will be replaced by a fluoride film or a phosphate film during the anodization process. If the anode is subjected to machining or other processing and oil stains are attached to the surface, it is necessary to go through a process such as pre-cleaning to remove the oil stains.

[0040] The material of the continuity holding jig 409 is a metal having a higher anodizing voltage than the anode used for anodization, and is anodized at a high voltage in advance. The material may be pure Mg, AZ31, AZ91, or the like, but is not limited to these.

[0041] The electrical continuity holding jig 409 sandwiching the anode 408 serves as the anode, and the carbon plate serves as the cathode, and are connected by electric wires to a stabilized DC power supply 410. Furthermore, the electrical continuity holding jig 409 of the cathode connected by the electric wire is immersed in the inner tank 403 to establish an anodic oxide film formation circuit.

[0042] Then, a voltage is applied between the anode and the cathode to form an anticorrosive film.

[0043] Figure 6 shows the current, voltage, and electrolyte temperature during the anodization process. In the figure, the solid line indicates the current value, the dashed line indicates the electrolyte temperature, and the dotted line indicates the voltage value. At 0 minutes into the treatment, a conductive holding jig 409 holding an Mg-Li alloy that will become the anode is immersed in the inner tank 403. At this time, a battery is formed when the anode comes into contact with the electrolyte, generating a small amount of current. In the current pattern shown in Figure 6, the current is passed one minute after the anode is immersed in the electrolyte, but there is no problem if the current is passed immediately after immersion.

[0044] Next, the power supply of the DC stabilized power supply 410 is turned on to allow the anodization reaction to proceed. The DC stabilized power supply is set to a maximum current value and is designed not to allow any current beyond that value. The voltage during the formation of the anodized film increases in accordance with the increase in electrical resistance of the Mg-Li alloy surface as the anticorrosive film grows.

[0045] The temperature of the electrolyte is kept constant by the function of a temperature control mechanism 404 attached to the device.

[0046] Finally, the timing to stop the current is determined by the cumulative current value passed through the Mg-Li alloy. To give a specific example, the amount of electricity required to grow a corrosion-resistant film by 1 μm is 100 cm 2 For example, if the surface area is 100 cm 2 When trying to form a 40 μm anticorrosive film on an Mg-Li alloy anode, the desired film thickness can be obtained by passing a current of 1741 coulombs (43.5 x 40) and then turning off the power.

[0047] Furthermore, the set value of the current can be determined by the surface area of ​​the anode and the current density. If the current density is low, the anodizing process takes a long time, which reduces productivity. If the current density is high, the anodizing process time is shortened and productivity improves, but if the current density is too high, the anodized film that is formed grows while undergoing dielectric breakdown, which may reduce durability. Therefore, the current density is set to 1A / 100cm. 2 From 10A / 100cm 2 By the above-described method, the alloy member according to the present disclosure can be obtained.

[0048] <Second embodiment> [Optical equipment / imaging devices] Fig. 7 shows the configuration of a single-lens reflex digital camera 600, which is an image capturing apparatus that is an example of an apparatus according to the second embodiment of the present disclosure. In Fig. 7, a camera body 602 and a lens barrel 601, which is an optical apparatus, are coupled together, and the lens barrel 601 is a so-called interchangeable lens that is detachable from the camera body 602.

[0049] Light from a subject passes through an optical system consisting of multiple lenses 603, 605, which are an example of components arranged on the optical axis of a photographing optical system inside a housing 620 of a lens barrel 601, and is received by an image sensor 610, thereby photographing the subject. Here, the lens 605 is supported by an inner cylinder 604, and is supported movably relative to the outer cylinder of the lens barrel 601 for focusing and zooming.

[0050] During an observation period before shooting, light from a subject is reflected by a main mirror 607, which is an example of a component in a housing 621 of the camera body, and after passing through a prism 611, a shooting image is projected to the photographer through a viewfinder lens 612. The main mirror 607 is, for example, a half mirror, and the light passing through the main mirror is reflected by a sub-mirror 608 in the direction of an AF (autofocus) unit 613, and this reflected light is used, for example, for distance measurement. The main mirror 607 is attached and supported by a main mirror holder 640 by adhesive or the like. During shooting, the main mirror 607 and the sub-mirror 608 are moved out of the optical path via a driving mechanism (not shown), a shutter 609 is opened, and a shooting light image incident from the lens barrel 601 is formed on an image sensor 610. The aperture 606 is configured so that the brightness and focal depth during shooting can be changed by changing the opening area.

[0051] The alloy member 100 can be used for at least a part of the housings 620 and 621. The housings constituting the housing 620 and the camera body 602 may be composed only of the alloy member of the present disclosure, or a coating film may be provided on the alloy member. Since the alloy member has excellent appearance and corrosion resistance, it is possible to provide an imaging device that is superior in appearance and corrosion resistance to conventional imaging devices.

[0052] Although the imaging device has been described using a single-lens reflex digital camera as an example, the present disclosure is not limited to this, and the imaging device may also be a smartphone or a compact digital camera.

[0053] <Third embodiment> [Electronic equipment] FIG. 8 shows the configuration of a personal computer, which is an electronic device that is an example of the device according to the third embodiment of the present disclosure. In FIG. 8, the personal computer 800 includes a display unit 801 and a main body unit 802. An electronic component 803, which is an example of a component provided in a housing, is provided inside a housing 820 of the main body unit 802. The alloy member 100 can be used for at least a part of the housing 820 of the main body unit 802. The housing 820 may be composed of only the alloy member, or a coating film may be provided on the alloy member. Since the alloy member of the present disclosure has excellent appearance and corrosion resistance, it is possible to provide a personal computer that is superior in appearance and corrosion resistance to conventional personal computers.

[0054] Although the electronic device has been described by taking the personal computer 800 as an example, the present disclosure is not limited to this, and the electronic device may be a smartphone or a tablet.

[0055] <Fourth embodiment> [Mobile object] FIG. 9 shows a drone, which is a moving object, as an example of the device according to the fourth embodiment of the present disclosure. The drone 700 includes a plurality of driving units 701 and a main body unit 702 connected to the driving units 701. The main body unit 702 includes a driving circuit 705, which is an example of a component. The driving unit 701 has, for example, a propeller. As shown in FIG. 9, the main body unit 702 may be connected to a leg unit 703, or may be configured to connect a camera 704. The alloy member can be used for at least a part of the housing 710 of the main body unit 702 and the leg unit 703. The housing 710 may be made of only the alloy member, or a paint film may be provided on the alloy member. The alloy member of the present disclosure has excellent appearance and corrosion resistance, and therefore it is possible to provide a drone with a better appearance and corrosion resistance than conventional drones.

[0056] Although drone 700 has been described as an example of a moving object, the present disclosure is not limited to this, and the moving object may be an automobile or an airplane. EXAMPLES

[0057] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples. The following description will be given with reference to FIGS.

[0058] <Manufacturing of alloy components> Example 1 First, pure water was added to 3680 g of ammonium fluoride and 2280 g of triammonium phosphate trihydrate to prepare an electrolyte solution 401 having a volume of 20 liters when completely dissolved.

[0059] The prepared electrolyte was poured into the outer tank of the anodization apparatus 400 shown in Fig. 5, and the magnet pump 405 was started. After the liquid in the inner tank overflowed and liquid circulation was started, the temperature control mechanism 404 was started to stabilize the liquid temperature at 20°C. Furthermore, a carbon plate functioning as a cathode was immersed in the inner tank and connected to the cathode of the power supply by a lead wire.

[0060] A die-cast substrate made of Ares (composition: Mg-9%Li-4%Al-1%Zn, manufactured by Anritsu Materials Technology Co., Ltd.) was prepared as the anode. The size was 160mm x 107mm x 2mm. The die-casting was performed using Sodick's LMI450M.

[0061] Next, a continuity holding jig 409 made of AZ31 material was prepared. The substrate continuity holding jig had a fixed hinge at the tip of an AZ31 round bar, and a movable hinge at a position 107 mm from the fixed hinge. The fixed hinge and the movable hinge were structured to be contracted with a Viton O-ring. This substrate continuity holding jig had been anodized in advance in the above electrolyte until no current flowed at a voltage of 140 V. This treatment was performed to facilitate the transmission of power to the substrate continuity holding jig. The substrate to be anodized was sandwiched between the substrate continuity holding jig that had been pre-treated, and was connected to the anode of the power supply with a conductor and immersed in the inner tank at a position facing the cathode.

[0062] The DC stabilized power supply 410 used was the PAT160-100TMX manufactured by Kikusui Electronics Co., Ltd. The input current was 17.65A (surface area: 353.1cm2 , Current density: 5A / 100cm 2 The target film thickness was set to 40 μm, and the input current was set to 6148 coulombs. When the specified amount of coulombs was reached, the current of the DC stabilized power supply was stopped.

[0063] The substrate and the substrate continuity holding jig after the anodization treatment were removed from the inner tank and washed with pure water to thoroughly wash away the electrolyte adhering to the surface. Thereafter, the substrate was dried in a clean oven at 60° C. to obtain the alloy member of Example 1.

[0064] Example 2 The electrolyte was prepared by adding pure water to 7820 g of ammonium fluoride and 570 g of triammonium phosphate trihydrate, and adjusting the volume to 20 liters when completely dissolved. The current density was 1 A / 100 cm 2 The amount of electricity input was set to 4611 coulombs. Except for that, the alloy part of Example 2 was obtained in the same manner as in Example 1.

[0065] Example 3 The electrolyte was adjusted to a volume of 20 L when completely dissolved by adding pure water to 7360 g of ammonium fluoride and 760 g of triammonium phosphate trihydrate. The amount of electricity input was set to 9222 coulombs. The alloy member of Example 3 was obtained in the same manner as in Example 1.

[0066] Example 4 The electrolyte was prepared by adding pure water to 6900g of ammonium fluoride and 950g of triammonium phosphate trihydrate, and adjusting the volume to 20 liters when completely dissolved. The current density was 10A / 100cm 2 The amount of electricity input was set to 9222 coulombs. Except for that, the alloy part of Example 4 was obtained in the same manner as in Example 1.

[0067] Example 5 The electrolyte was adjusted to a volume of 20 liters when completely dissolved by adding pure water to 5060 g of ammonium fluoride and 1710 g of triammonium phosphate trihydrate. The amount of electricity input was set to 11527 coulombs. The substrate was cut out from a cast block material into the same shape as in Example 1. The alloy member of Example 5 was obtained in the same manner as in Example 1 except for the above.

[0068] Example 6 The electrolyte was adjusted to a volume of 20 liters when completely dissolved by adding pure water to 2760 g of ammonium fluoride and 2660 g of triammonium phosphate trihydrate. The amount of electricity input was set to 7685 coulombs. The anode substrate was a LAZ771 material (composition: Mg-7%Li-7%Al-1%Zn, manufactured by Anritsu Materials Technology Co., Ltd.) that was thixotropically molded, and had the same shape as in Example 1. The alloy member of Example 6 was obtained in the same manner as in Example 1 except for the above.

[0069] Comparative Example 1 The electrolyte was adjusted to a volume of 20 L when 9000 g of ammonium fluoride was completely dissolved in pure water. The amount of electricity input was set to 9328 coulombs. The alloy member of Comparative Example 1 was obtained in the same manner as in Example 1.

[0070] Comparative Example 2 The electrolyte was adjusted to a volume of 20 liters when completely dissolved by adding pure water to 8280 g of ammonium fluoride and 380 g of triammonium phosphate trihydrate. The amount of electricity input was set to 12296 coulombs. The alloy member of Comparative Example 2 was obtained in the same manner as in Example 1.

[0071] Comparative Example 3 The electrolyte was adjusted to a volume of 20 liters when completely dissolved by adding pure water to 1840 g of ammonium fluoride and 3040 g of triammonium phosphate trihydrate. The amount of electricity input was set to 15370 coulombs. The alloy member of Comparative Example 3 was obtained in the same manner as in Example 1.

[0072] These production conditions are summarized in Table 1.

[0073] [Table 1]

[0074] <Evaluation> (Film thickness variation evaluation results) The thickness of the anticorrosive film on the alloy members of the examples and comparative examples was measured. The film thickness was evaluated using an eddy current film thickness meter SWT-9000 (probe: NF-0.6) manufactured by Sanko Electronics Laboratory Co., Ltd. For film thickness measurement locations, for those with uniform appearance, measurements were taken at five random locations in the uniform appearance area, and the difference between the maximum and minimum measured values ​​(maximum film thickness difference) was evaluated. For film thickness measurement locations of Comparative Examples 1 to 3, where the appearance was divided into white and gray areas, measurements were taken at five points in the white area and five points in the gray area, and the difference between the maximum and minimum measured values ​​(maximum film thickness difference) was evaluated. The results are shown in Table 2.

[0075] [Table 2]

[0076] From these results, it can be seen that the anticorrosive film with a maximum thickness difference of less than 20 μm had a uniform white appearance. On the other hand, the comparative example with a maximum thickness difference of 20 μm or more had an appearance that was separated into white and gray areas, resulting in noticeable unevenness. These samples were painted and the appearance of the painted surfaces was compared. As a result, the sample of the embodiment was uniform, but the comparative example, even after painting, had island-like unevenness in the gray areas that were visible as steps.

[0077] Table 2 also shows that in alloy components that were visually uniform in appearance and had a white color, the concentration of ammonium fluoride was in the range of 100 g / L to 400 g / L, and the concentration of triammonium phosphate trihydrate was in the range of 20 g / L to 140 g / L.

[0078] (EDS elemental analysis results) The alloy members obtained in the examples and comparative examples were subjected to elemental analysis by EDS (energy dispersive X-ray spectrometry).

[0079] For the EDS elemental analysis, a JSM-F100 (FE-SEM) device manufactured by JEOL Ltd. was used. The elements analyzed by EDS were Mg, P, F, O, C, and Al. The analysis conditions were an acceleration voltage of 13 kV and a working distance of 9.5 mm to 10 mm.

[0080] The measurement positions were the x marks 103 in Figure 1, and the anticorrosive coating 102 was divided into seven parts in the thickness direction. The elemental composition analysis was performed by EDS at six points marked with x, excluding the interface between the base substrate and the anticorrosive coating and the vicinity of the surface layer. The average elemental ratios of three points on the coating side and three points on the surface layer side were evaluated. The results are shown in Table 3.

[0081] [Table 3]

[0082] In Table 3, the detected amount of fluorine F1 is the measured value in the region 102B, and F2 is the measured value in the region 102A. In addition, the detected amount of phosphorus P1 is the measured value in the region 102B, and P2 is the measured value in the region 102A.

[0083] These results show that no uneven appearance of the anti-corrosion film occurs when the detected amount of fluorine atoms is in the range of 9 atomic % or more and 66 atomic % or less, the detected amount of phosphorus atoms is in the range of 2 atomic % or more and 26 atomic % or less, and the detected amount of magnesium atoms (Mg) is in the range of 14 atomic % or more and 38 atomic % or less.

[0084] In addition, the relationship of F1 > F2 is confirmed for the detected amount of fluorine. Furthermore, the relationship of P1 < P2 is confirmed for the detected amount of phosphorus. Here, it can be understood that the ammonium ion concentration range in which good products can be obtained is 5.7 mol / L or more and 11 mol / L or less. Note that after leaving the samples prepared in the examples and comparative examples in an environment of 60 °C and 85% relative humidity for 1000 hours after coating, no defects such as coating film swelling or coating film peeling occurred.

[0085] As described above, according to the present disclosure, since the average film thickness T of the anticorrosive film is 20 μm or more, excellent corrosion resistance can be obtained even when an alloy mainly composed of magnesium and containing lithium is used for the base material. In addition, since the difference between the maximum value and the minimum value of the film thickness of the anticorrosive film is less than 20 μm, excellent appearance can be obtained even when an alloy mainly composed of magnesium and containing lithium is used for the base material. Therefore, according to the present disclosure, an alloy member that achieves both corrosion resistance and good appearance can be provided.

[0086] Note that the present disclosure is not limited to the embodiments described above, and many modifications are possible within the technical idea of the present disclosure. In addition, the effects described in the embodiments are merely an enumeration of the most preferable effects resulting from the present disclosure, and the effects according to the present disclosure are not limited to those described in the embodiments.

[0087] The present disclosure includes the following.

[0088] (Item 1) A base material mainly composed of magnesium and containing lithium, and An anticorrosive film provided on the base material and containing magnesium, phosphorus, and fluorine, the alloy member comprising: The average film thickness T of the anticorrosive film is 20 μm or more, An alloy member characterized in that the difference between the maximum value and the minimum value of the film thickness of the anticorrosive film is less than 20 μm.

[0089] (Item 2) Item 2. The alloy member according to item 1, wherein the phosphorus concentration P1 in a region of the anticorrosive film up to a thickness T / 2 on a side closer to the substrate is lower than the phosphorus concentration P2 in a region of the anticorrosive film up to a thickness T / 2 on a side farther from the substrate.

[0090] (Section 3) Item 3. The alloy member according to item 1 or 2, wherein the fluorine concentration F1 in a region of the anticorrosive film up to a thickness T / 2 on a side closer to the substrate is higher than the fluorine concentration F2 in a region of the anticorrosive film up to a thickness T / 2 on a side farther from the substrate.

[0091] (Section 4) 4. The alloy member according to any one of items 1 to 3, wherein the anticorrosive film contains an inorganic fluoride.

[0092] (Section 5) 5. The alloy member according to item 4, wherein the inorganic fluoride is mainly composed of magnesium fluoride.

[0093] (Section 6) In the anticorrosion film, The magnesium content is in the range of 14 atomic % or more and 38 atomic % or less, The phosphorus content is in the range of 2 atomic % or more and 26 atomic % or less, 6. The alloy structural member according to any one of items 1 to 5, wherein the fluorine content is in the range of 9 atomic % to 66 atomic %.

[0094] (Section 7) 7. The alloy structural member according to any one of items 1 to 6, wherein in the substrate, the sum of the magnesium content and the lithium content is 90 mass % or more.

[0095] (Section 8) Item 8. The alloy member according to item 7, wherein the lithium content in the substrate is in the range of 0.5% by mass to 15% by mass.

[0096] (Section 9) Item 9. The alloy member according to item 8, wherein the lithium content in the substrate is in the range of 5% by mass to 11% by mass.

[0097] (Section 10) The substrate contains aluminum, Item 10. The alloy member according to any one of items 7 to 9, wherein the aluminum content in the base material is in the range of 1% by mass to 8% by mass.

[0098] (Section 11) the substrate contains germanium and / or beryllium; Item 11. The alloy member according to any one of items 7 to 10, wherein the content of germanium and / or beryllium in the base material is in the range of 0.02 mass% or more and 0.4 mass% or less.

[0099] (Section 12) In the substrate, The germanium content is in the range of 0.04% by mass or more and 0.4% by mass or less, Item 12. The alloy structural member according to item 11, wherein the beryllium content is in the range of 0.02% by mass to 0.1% by mass.

[0100] (Section 13) The substrate contains zirconium; Item 13. The alloy structural member according to any one of Items 7 to 12, wherein the zirconium content in the base material is 0.6% by mass or more and 3.0% by mass or less.

[0101] (Section 14) The substrate contains at least one element selected from the group consisting of zinc, calcium, silicon, and manganese; Item 14. The alloy structural member according to any one of items 7 to 13, wherein the sum of the contents of the elements in the group in the base material is in the range of 0.01% by mass to 5% by mass.

[0102] (Section 15) The zinc content is 3% by mass or less, The calcium content is 1% by mass or less, The silicon content is 0.2% by mass or less, The manganese content is 0.3% by mass or less, Item 15. The alloy member according to item 14, wherein the balance is inevitable impurities and the magnesium.

[0103] (Section 16) A housing and A component provided in the housing, Item 16. An apparatus characterized in that the housing comprises the alloy member according to any one of items 1 to 15.

[0104] (Section 17) placing an anode and a cathode in an electrolyte; and applying a voltage between the anode and the cathode to form an anticorrosive film on the anode, The anode is composed mainly of magnesium and contains lithium, The electrolyte contains fluorine ions, ammonium ions, and phosphate ions, A method for producing an alloy member, wherein a concentration of the ammonium ions in the electrolyte is in the range of 5.7 mol / L or more and 11 mol / L or less.

[0105] (Section 18) Item 18. The method for producing an alloy member according to item 17, wherein the electrolytic solution is a solution of ammonium fluoride and triammonium phosphate.

[0106] (Section 19) In the electrolytic solution, The concentration of the fluorine ions is in the range of 2.5 mol / L or more and 10.6 mol / L or less, Item 19. The method for producing an alloy member according to item 17 or 18, wherein the concentration of the phosphate ions is in the range of 0.14 mol / L or more and 0.65 mol / L or less. [Explanation of symbols]

[0107] 100 Alloy components 101 Base material 102 Anticorrosive film 400 Anodizing Equipment 600 Single-lens reflex digital camera (imaging device) 601 Lens barrel (optical equipment) 700 Drone (Mobile) 800 Personal computers (electronic devices)

Claims

1. A substrate containing magnesium as a main component and lithium; An alloy member comprising: an anticorrosive film provided on the substrate and containing magnesium, phosphorus, and fluorine, The average thickness T of the anticorrosive film is 20 μm or more, An alloy member, characterized in that the difference between the maximum and minimum film thicknesses of the anticorrosion film is less than 20 μm.

2. 2. The alloy member according to claim 1, wherein the phosphorus concentration P1 in a region of the anticorrosion film up to a thickness T / 2 on a side closer to the substrate is lower than the phosphorus concentration P2 in a region of the anticorrosion film up to a thickness T / 2 on a side farther from the substrate.

3. 2. The alloy member according to claim 1, wherein the fluorine concentration F1 in a region of the anticorrosion film up to a thickness T / 2 on a side closer to the substrate is higher than the fluorine concentration F2 in a region of the anticorrosion film up to a thickness T / 2 on a side farther from the substrate.

4. The alloy member according to claim 1 , wherein the anticorrosive film contains an inorganic fluoride.

5. 5. The alloy member according to claim 4, wherein the inorganic fluoride is mainly composed of magnesium fluoride.

6. In the anticorrosion film, The magnesium content is in the range of 14 atomic % or more and 38 atomic % or less, The phosphorus content is in the range of 2 atomic % or more and 26 atomic % or less, 2. The alloy member according to claim 1, wherein the fluorine content is in the range of 9 atomic % to 66 atomic %.

7. 2. The alloy structural member according to claim 1, wherein in the substrate, a sum of a content of the magnesium and a content of the lithium is 90 mass % or more.

8. The alloy structural member according to claim 7 , wherein the lithium content in the substrate is in the range of 0.5% by mass to 15% by mass.

9. The alloy structural member according to claim 8 , wherein the content of the lithium in the substrate is in the range of 5 mass % to 11 mass %.

10. The substrate contains aluminum, The alloy structural member according to claim 7 , wherein the aluminum content in the base material is in the range of 1 mass % to 8 mass %.

11. the substrate contains germanium and / or beryllium; The alloy structural member according to claim 7, wherein the content of the germanium and / or beryllium in the base material is in the range of 0.02 mass % or more and 0.4 mass % or less.

12. In the substrate, The germanium content is in the range of 0.04 mass% or more and 0.4 mass% or less, The alloy structural member according to claim 11, wherein the beryllium content is in the range of 0.02 mass % to 0.1 mass %.

13. The substrate contains zirconium; The alloy structural member according to claim 7, wherein the zirconium content in the base material is 0.6 mass % or more and 3.0 mass % or less.

14. The substrate contains at least one element selected from the group consisting of zinc, calcium, silicon, and manganese; The alloy structural member according to claim 7, wherein the sum of the contents of the elements in the group in the base material is in the range of 0.01% by mass to 5% by mass.

15. The zinc content is 3% by mass or less, The calcium content is 1% by mass or less, The silicon content is 0.2 mass% or less, The manganese content is 0.3% by mass or less, The alloy member according to claim 14, wherein the balance is inevitable impurities and said magnesium.

16. A housing and A component provided in the housing, An apparatus, characterized in that the housing comprises the alloy part according to any one of claims 1 to 15.

17. placing an anode and a cathode in an electrolyte; and applying a voltage between the anode and the cathode to form an anticorrosive film on the anode, The anode is composed mainly of magnesium and contains lithium, The electrolyte contains fluorine ions, ammonium ions, and phosphate ions, A method for producing an alloy member, wherein a concentration of the ammonium ions in the electrolytic solution is in the range of 5.7 mol / L or more and 11 mol / L or less.

18. The method for producing an alloy part according to claim 17, wherein the electrolyte is a solution of ammonium fluoride and triammonium phosphate.

19. In the electrolytic solution, The concentration of the fluorine ions is in the range of 2.5 mol / L or more and 10.6 mol / L or less, The method for producing an alloy structural member according to claim 17, wherein the concentration of the phosphate ions is in the range of 0.14 mol / L or more and 0.65 mol / L or less.

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