Nickel-based alloy plating solution

Abstract

The present invention addresses the problem of providing a plating solution and a plating method, with which it is possible to form an Ni-Cr-(Mo / W)-based alloy film with more uniform composition and more uniform film thickness because of excellent uniform electrodeposition properties. Provided is a plating solution for forming an Ni-Cr-(Mo / W)-based alloy film, the plating solution containing a metal ion source that includes ion sources of nickel, chromium, and molybdenum and / or tungsten, and a complexing agent. The amount of the complexing agent with respect to the total amount of the metal ion source is 0.01 equivalent to 2 equivalents inclusive. Also provided is a method for forming an Ni-Cr-(Mo / W)-based alloy film, the method including a step for plating with use of the plating solution.

Description

Nickel alloy plating solution

[0001] The present invention relates to a plating solution for forming a nickel-based alloy film.

[0002] Conventionally, nickel-based alloys such as HASTELLOY (registered trademark) have been widely used as heat-resistant and corrosion-resistant materials. These nickel-based alloys have excellent heat resistance and corrosion resistance, exhibit high durability against halogens and various oxidizing and non-oxidizing chemical substances, and have the advantages of being resistant to pitting corrosion and crevice corrosion and stress corrosion cracking.

[0003] Because of these advantages, nickel-based alloys can be used in high-temperature and corrosive environments, but they also have the disadvantage of being hard and difficult to process. Therefore, materials using nickel-based alloys are difficult to process into complex shapes, and in addition, the material itself is expensive, so they tend to be expensive. Nickel-based alloys also have the disadvantage of having a relatively high specific gravity, making it difficult to reduce the weight of the material.

[0004] If nickel-based alloys could be applied to various materials in the form of surface coatings, it would be possible to overcome the difficulties in formability and facilitate cost and weight reduction. Based on this idea, several attempts have been made to form nickel-based alloy coatings by plating.

[0005] For example, Patent Document 1 discloses a method for plating an alloy using a plating bath containing specific concentrations of chromium ions, nickel and / or cobalt ions, and tungstic acid, molybdic acid, and / or rhenic acid ions. Patent Document 2 discloses a plating solution with a pH of 8 to 11 in which gluconate is selected as a complexing agent for nickel-based alloy plating and is blended with a nickel salt and a molybdic acid to improve the formation efficiency and appearance of the plating film.

[0006] Japanese Patent Laid-Open No. 9-302496 Japanese Patent Laid-Open No. 2005-082856

[0007] The conventional methods described above do not necessarily provide uniform nickel-based alloy plating films with excellent corrosion resistance and other properties. For example, with the plating method described in Patent Document 1, it is difficult to uniformly electrodeposit a nickel-chromium-molybdenum alloy film, as will be shown in the examples described later. Similar problems can also occur with the plating solution described in Patent Document 2, in which the type of complexing agent is considered. The nickel-molybdenum alloy plating solution described in Patent Document 2 also does not contain chromium ions, making it difficult to achieve sufficient acid resistance and other properties. Simply adding a chromium salt to this plating solution does not necessarily result in a uniform plating film with a good appearance.

[0008] In order to solve the above-mentioned problems, an object of the present invention is to provide a plating solution that has excellent throwing power and is capable of forming a nickel-chromium-molybdenum and / or tungsten-based alloy film with a more uniform composition and film thickness, and a method for forming a plating film using the plating solution.

[0009] The present inventors have discovered that when forming a coating of a nickel-chromium-molybdenum and / or tungsten-based alloy (Ni—Cr—(Mo / W)-based alloy), by setting the ratio of the amount of complexing agent to the amount of ion source within a specific range, specifically, to 2 equivalents or less, a nickel-based alloy coating can be obtained without significant variations in composition or film thickness, and have completed the present invention.

[0010] That is, the present invention provides the following (1) to (8): (1) A plating solution for forming a Ni—Cr—(Mo / W)-based alloy film, comprising a metal ion source, including a nickel, chromium, and molybdenum and / or tungsten ion source, and a complexing agent, wherein the amount of the complexing agent relative to the total amount of the metal ion source is 0.01 equivalents or more and 2 equivalents or less. (2) The plating solution of (1) above, further comprising a conductive salt. (3) The plating solution of (2) above, wherein the conductive salt comprises a sulfate. (4) Any of the plating solutions of (1) to (3) above, further comprising a pH adjuster containing an alkali metal hydroxide. (5) Any of the plating solutions of (1) to (4) above, wherein the complexing agent is one or more selected from the group consisting of a carboxylic acid, a carboxylate salt, a hydroxycarboxylic acid, a hydroxycarboxylate salt, an amino acid, an amino acid salt, and an alcohol. (6) Any of the plating solutions of (1) to (5) above, further comprising a pH buffer. (7) The plating solution according to any one of (1) to (6) above, wherein the nickel concentration is 0.001 to 0.5 mol / L in terms of element, the chromium concentration is 0.01 to 1.5 mol / L in terms of element, and the total concentration of the molybdenum and the tungsten is within the range of 0.001 to 2.0 mol / L in terms of element. (8) A method for forming a Ni—Cr—(Mo / W) based alloy film, comprising the step of plating using the plating solution according to any one of (1) to (7) above.

[0011] The plating solution of the present invention has excellent throwing power, and the plating solution and method of the present invention make it possible to form a Ni—Cr—(Mo / W) alloy coating without large variations in composition or film thickness.

[0012] FIG. 1 is a photograph showing the results of a corrosion resistance test (Reference Example 1) for plated part samples obtained in Examples 2, 7, and 8 according to the present invention, together with the results for other plated part samples.

[0013] The present invention will be described in detail below based on embodiments, but the present invention is not limited to these embodiments.

[0014] 1. Plating Solution The plating solution according to this embodiment is a plating solution for forming a Ni—Cr—(Mo / W)-based alloy film, containing a metal ion source including ion sources of nickel, chromium, and molybdenum and / or tungsten, and a complexing agent, in which the amount of the complexing agent relative to the total amount of the metal ion source is 0.01 equivalents or more and 2 equivalents or less.

[0015] <Metal Ion Source> The metal ion source contained in the plating solution contains at least ion sources of nickel, chromium, and molybdenum and / or tungsten.

[0016] Common ion sources include, for example, nickel salts, chromium salts, various chromates, molybdenum salts, various molybdates, tungsten salts, and various tungstates, and these can also be used in this embodiment. It is also possible to use multiple ion sources of the same metal, such as a chromium salt and a chromate, in combination. Salts such as nickel molybdate can also be used. In addition to these, salts of complex ions, such as ammonium complexes and cyano complexes of various metal ions, may also be used. However, in order to optimize the content ratio with the complexing agent, which is the other essential component, and to form a plating film with a uniform composition and thickness, it is preferable to use a metal salt or metal acid salt that is not a complex as the metal ion source.

[0017] More preferred metal ion sources are nickel salts, chromium salts, molybdates, and tungstates. Among these, nickel and chromium halides, sulfates, sulfites, nitrates, nitrites, perchlorates, etc., and sodium, potassium, and ammonium salts of molybdic acid and tungstic acid are preferred. Nickel sulfate, chromium sulfate, basic chromium sulfate, ammonium molybdate, and ammonium tungstate are particularly suitable as metal ion sources in this embodiment. Plating solutions containing these metal ion sources can form highly corrosion-resistant Ni—Cr—(Mo / W)-based alloy coatings with more uniform composition and thickness.

[0018] The metal ion source may further contain other metals, such as iron (Fe), cobalt (Co), manganese (Mn), copper (Cu), titanium (Ti), niobium (Nb), and aluminum (Al). The use of these other metal ion sources in combination can also form nickel-based alloy coatings with compositions such as Hastelloy X, a Ni-Cr-Mo-Fe system containing small amounts of Mn and Co, as well as Inconel, Incoloy, Waspaloy, and DASALOY (registered trademark). If desired, phosphates, silicates, and the like may be used in combination to form nickel-based alloy coatings containing phosphorus (P) and silicon (Si). The plating solution of this embodiment may also enable the formation of alloy coatings with compositions that cannot be produced by metallurgical techniques.

[0019] <Complexing Agent> The plating solution of this embodiment contains a complexing agent together with a metal ion source. In this embodiment, any type of complexing agent may be used as long as the amount thereof is appropriate, as will be described later, and a conventional complexing agent can be used.

[0020] Specific examples of the complexing agent include cyanides; various carboxylic acids and their salts; various amino acids and their salts; phosphorus-containing compounds such as pyrophosphates, nitrilotrimethylphosphonic acid and their salts, and tris(3-hydroxypropyl)phosphine; sulfur-containing compounds such as thiourea, thioglycolic acid, thiodiglycolic acid, thioglycol, thiodiglycol, mercaptosuccinic acid, 3,6-dithia-1,8-octanediol, 3,6,9-trithiadecane-1,11-disulfonic acid, thiobis(dodecaethylene glycol), di(6-methylbenzothiazolyl)disulfide trisulfonic acid, di(6-chlorobenzothiazolyl)disulfide disulfonic acid, dithiodianiline, dipyridyl disulfide, mercaptosuccinic acid, sulfites, and thiosulfates; and alcohols; and further, ethylenediamine, ascorbic acid, gluconolactone, and glucoheptonolactone, but are not limited to these. It is also possible to use a plurality of types of complexing agents in combination.

[0021] The complexing agent is preferably one or more selected from the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylates, amino acids, amino acid salts, and alcohols. A plating solution containing an appropriate amount of such a complexing agent can form a nickel-based alloy plating film with a more uniform composition and thickness. Among these, carboxylic acids, hydroxycarboxylic acids, and their salts, and hydroxycarboxylic acids in particular, are preferred. These complexing agents will be described in more detail below, but the complexing agents that can be used as components of the plating solution of this embodiment are not limited to those listed below.

[0022] (Carboxylic Acid and Its Salt) Carboxylic acids suitable as complexing agents include aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, and hexanoic acid; aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, maleic acid, and malic acid; aliphatic tricarboxylic acids such as aconitic acid; and aromatic carboxylic acids such as benzoic acid, salicylic acid, phthalic acid, and cinnamic acid. Carboxylic acid salts include their sodium salts, potassium salts, and ammonium salts. The salt of a carboxylic acid having multiple carboxy groups may be a salt formed by only some of the carboxy groups, or a double salt, such as sodium hydrogen oxalate or potassium sodium oxalate.

[0023] (Hydroxycarboxylic acid and its salt) Examples of hydroxycarboxylic acid suitable as a complexing agent include glycolic acid, gluconic acid, citric acid, glucoheptonic acid, tartaric acid, diglycolic acid, etc. Examples of hydroxycarboxylic acid salts include sodium salts, potassium salts, ammonium salts, etc. For example, sodium hydrogen tartrate and potassium sodium tartrate may be used.

[0024] (Amino Acids and Their Salts) Examples of amino acids (aminocarboxylic acids) suitable as complexing agents include glycine, α-alanine, β-alanine, cystine, anthranilic acid, aspartic acid, glutamic acid, aminodiacetic acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraminehexaacetic acid (TTHA), ethylenedioxybis(ethylamine)-N,N,N',N'-tetraacetic acid, and aromatic amino acids such as pyridinedicarboxylic acid. Examples of amino acid salts include sodium salts, potassium salts, and ammonium salts thereof.

[0025] (Alcohol) Examples of alcohols suitable as complexing agents include glycols such as ethylene glycol, propylene glycol, and diethylene glycol.

[0026] <Amount of Metal Ion Source and Amount of Complexing Agent> The plating solution of this embodiment is characterized in that the amount of complexing agent relative to the total amount of metal ion sources is 0.01 equivalents or more and 2 equivalents or less. By setting the ratio of the amount of complexing agent to the amount of metal ion source within the range of 0.01 to 2 equivalents, the throwing power of the plating solution can be improved, and a nickel-based alloy coating can be formed with a more uniform composition and film thickness.

[0027] Generally, alloy plating uses multiple metals with different deposition potentials. Therefore, to form a desired alloy film with a uniform composition, a complexing agent is often used in an amount greater than or equal to the metal ion source. For example, in the example described in Patent Document 1, multiple organic acids are used as complexing agents in a total amount greater than 2 to 4 equivalents relative to the total molar amount of metal ions. Even in the nickel-molybdenum alloy plating solution described in Patent Document 2, when the amount of complexing agent is about 2 equivalents relative to the amount of metal ion source, the deposition current efficiency of the plating film does not increase, and is significantly reduced, particularly when the amount is 1 equivalent or less. In the current study, an unexpected effect was demonstrated in forming a plating film of nickel, chromium, and molybdenum and / or tungsten-based alloys (Ni—Cr—(Mo / W)-based alloys), by using a small amount of complexing agent, 0.01 to 2 equivalents relative to the total amount of metal ion source, resulting in a plating solution with excellent throwing power.

[0028] Here, "equivalent" means the ratio of the molar amount of complexing agent molecules to the total molar amount of metal ions that make up the plating film.

[0029] Furthermore, the "total amount of metal ion sources" refers to the sum of the molar amounts of all ion sources for the metals that constitute the target plating film. For example, when forming a Ni-Cr-(Mo / W) alloy film, it refers to the total molar amount of nickel, chromium, and molybdenum and / or tungsten; when forming a Ni-Cr-(Mo / W)-Fe alloy film, it refers to the total molar amount of nickel, chromium, molybdenum and / or tungsten, and iron. It does not include the amount of metals that do not constitute the plating film, such as alkali metals in molybdates. Generally, it refers to the total molar amount of metals from Groups 3 to 15, for example, Groups 4 to 14, in the plating solution.

[0030] The "molar amount of the metal ion source" is a value based on the metal element, for example, 0.1 mole of Cr in the plating solution. ２ (SO ４ ) ３ When the chromium ion source is contained, the amount of the chromium ion source is calculated as 0.2 mole.

[0031] (Concentration of Metal Component) In relation to the amount of the metal ion source, the concentration of each metal component will be described. The concentration of the metal component in the plating solution of this embodiment can be set as desired depending on the type of the target plating film, the plating treatment conditions, etc. For example, the nickel concentration may be set to 0.001 to 0.5 mol / L in elemental terms, the chromium concentration may be set to 0.01 to 1.5 mol / L in elemental terms, and the total concentration of molybdenum and tungsten may be set to 0.001 to 2.0 mol / L in elemental terms.

[0032] Alternatively, the concentrations of these metal components may be set, in elemental terms, such that the nickel concentration is 0.001 to 0.5 mol / L, particularly 0.01 to 0.1 mol / L, the chromium concentration is 0.01 to 1.5 mol / L, particularly 0.1 to 1.0 mol / L, and the molybdenum concentration is 0.001 to 2.0 mol / L, particularly 0.01 to 1.0 mol / L, and if desired, tungsten may be used in place of or in addition to molybdenum to a concentration of about 0.001 to 2.0 mol / L, particularly 0.01 to 1.0 mol / L.

[0033] In the plating solution of this embodiment, as described above, the amount of complexing agent relative to the total amount of metal ion sources, i.e., the molar ratio of complexing agent amount to total amount of metal ion sources, is 0.01 equivalents or more and 2 equivalents or less. Preferably, the molar ratio of complexing agent amount to total amount of metal ion sources is, for example, 0.05 equivalents or more, more preferably 0.10 equivalents or more, even more preferably 0.20 equivalents or more, even more preferably 0.30 equivalents or more, and particularly preferably 0.40 equivalents or more. The molar ratio is also preferably set to 1.5 equivalents or less, more preferably 1.0 equivalents or less, particularly preferably 0.90 equivalents or less, even more preferably 0.8 equivalents or less, or even 0.6 equivalents or less, for example, 0.10 to 2.0 equivalents, particularly 0.20 to 1.5 equivalents, further preferably 0.30 to 1.0 equivalents, and particularly preferably 0.40 to 0.90 equivalents.

[0034] In this way, by appropriately selecting the molar ratio of the amount of complexing agent to the total amount of metal ion source within the range of 0.01 to 2 depending on the target plating film, the type of complexing agent, etc., it is possible to form a nickel-based alloy film with a more uniform composition and film thickness. The concentration of the complexing agent in the plating solution is determined mainly based on the total concentration of the metal ion sources, but it is generally preferably about 0.01 to 1 mol / L, and particularly about 0.1 to 0.8 mol / L.

[0035] <Solvent> In the plating solution of this embodiment, the solvent containing the metal ion source and complexing agent is preferably water, but may also contain organic solvents such as alcohols such as methanol and ethanol; ethers such as tetrahydrofuran (THF), dioxane, and various glymes; carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; nitrogen-containing solvents such as acetonitrile, dimethylformamide (DMF), and pyrrolidone; and sulfur-containing solvents such as dimethyl sulfoxide (DMSO). Depending on the purpose and the types of metal salt and complexing agent used, the organic solvent may be used as the main solvent.

[0036] <Additives> In addition to the metal ion source and complexing agent, the plating solution of this embodiment may contain various additives, such as conductivity imparting agents (e.g., conductive salts), pH adjusters, pH buffers, hydrogen generation inhibitors, dispersants, dispersion aids, emulsifiers, surfactants, brighteners, antioxidants, viscosity adjusters, wetting agents, and pigments. In particular, the addition of conductive salts, pH adjusters, and pH buffers can further improve the throwing power of the plating solution. Some of these additives are described below.

[0037] (Conductive Salt) The type of conductive salt is not particularly limited, and various inorganic salts such as halides, sulfates, nitrates, and phosphates, as well as organic salts such as tetraalkylammonium salts, pyridinium salts, and sulfonates, can be used. Among these, sulfates and / or ammonium salts, particularly sulfates, are preferred. A plating solution containing sulfates or ammonium salts as conductive salts promotes balanced deposition of the metals that form the desired coating, making it easier to form alloy plating with more uniform composition and film thickness. Specific examples of suitable conductive salts include, but are not limited to, sodium sulfate, potassium sulfate, ammonium sulfate, ammonium chloride, ammonium bromide, ammonium nitrate, and ammonium phosphate. Sodium sulfate, potassium sulfate, and ammonium sulfate are particularly preferred.

[0038] There is no particular limitation on the concentration of these conductive salts in the plating solution, and they can be set to a desired value depending on the concentration of the metal components, etc. For example, the concentration may be about 0.1 to 3 mol / L, particularly about 0.25 to 2 mol / L, but is not limited to these ranges.

[0039] (pH Adjuster) The plating solution of the present embodiment may contain a pH adjuster to further improve the throwing power, and the pH may be adjusted to a range suitable for nickel-based alloy plating, for example, 0.5 to 12, particularly about 0.5 to 10, further about 0.5 to 7.5, and particularly about 1 to 6.

[0040] The pH adjuster is also useful in that it can make the complexing agent function effectively. Each complexing agent has a pH at which it is more likely to form a complex, so it is preferable to adjust the pH of the plating solution before use. Alternatively, the plating solution may be subjected to a process known as "aging," in which the solution is maintained at a specific temperature and pH for a certain period of time. It is preferable to use a pH adjuster during such a process.

[0041] The pH adjuster added to the plating solution of this embodiment is not particularly limited, and various acids and / or bases can be used depending on the pH during the intended plating treatment or aging. Here, using a pH adjuster containing sulfuric acid as the acid or a pH adjuster containing an alkali metal hydroxide and / or ammonia as the base is preferable, as it provides the advantage of improving the conductivity of the plating solution.

[0042] (pH Buffer) The plating solution of this embodiment preferably further contains a pH buffer to stabilize the deposition reaction of the target metal. Although a pH buffer can be considered a type of pH adjuster in the broad sense, it is treated here as a component different from a pH adjuster in the narrow sense. There are no particular limitations on the type of pH buffer, and a buffer suitable for the target pH range can be selected and used from various known buffers. Examples include, but are not limited to, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and salts thereof.

[0043] (Hydrogen Generation Inhibitor) The plating solution of this embodiment may also contain a hydrogen generation inhibitor. By including a hydrogen generation inhibitor in the plating solution, it becomes easier to suppress a decrease in current efficiency during plating. Furthermore, as a result of suppressing hydrogen gas generation at the cathode, it becomes easier to prevent scorching and hydrogen embrittlement of the plating film. Scorching (burning) is a defect in which the current density at the cathode becomes excessive, resulting in the formation of a rough and brittle plating film, and is a phenomenon caused by the precipitation of metal hydroxides due to an increase in pH at the cathode interface. There are no particular limitations on the hydrogen generation inhibitor, and various known ones can be used. For example, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and salts thereof can be used, with boric acid, citric acid, and salts thereof being particularly preferred.

[0044] When a hydrogen generation inhibitor is contained, its concentration is preferably about 0.01 to 2.0 mol / L, particularly about 0.1 to 1.5 mol / L. Some of these hydrogen generation inhibitors can also function as the complexing agent or pH buffer described above. Therefore, by adjusting the concentration of, for example, citric acid in the plating solution to about 0.01 to 2.0 mol / L, further about 0.02 to 1.5 mol / L, particularly about 0.10 to 1.0 mol / L, it is possible to achieve all of the functions of complex formation, pH adjustment, and hydrogen generation inhibition.

[0045] (Brightener) The plating solution of this embodiment may contain a brightener. Brighteners not only impart brightness to the plating film, but may also promote metal deposition in recesses and flatten the plating surface. There are no particular limitations on the type of brightener, and various aldehydes, triazines, imidazole, indole, quinoline, 2-vinylpyridine, aniline, phenanthroline, neocuproine, picolinic acid, thioureas, benzothiazoles, sulfides, and the like can be used. When a brightener is contained, its concentration is preferably about 0.01 mg / L to 500 mg / L, and particularly preferably about 0.1 mg / L to 10 mg / L.

[0046] (Surfactant) The surfactant is not particularly limited, and a desired surfactant can be selected from ordinary anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. When a surfactant is contained, its concentration is preferably about 1 mg / L to 50 g / L, particularly about 5 mg / L to 10 g / L.

[0047] (Antioxidant) The antioxidant is used to prevent oxidation of the metal salt. Examples of the antioxidant include, but are not limited to, hypophosphorous acids, ascorbic acid, phenolsulfonic acid, cresolsulfonic acid, hydroquinonesulfonic acid, hydroquinone, α- or β-naphthol, catechol, resorcinol, phloroglucinol, hydrazine, phenolsulfonic acid, catecholsulfonic acid, hydroxybenzenesulfonic acid, naphtholsulfonic acid, and salts thereof. The antioxidant can be contained at a concentration of, for example, about 0.1 g / L to 500 g / L, particularly about 1 g / L to 100 g / L.

[0048] Although several representative additives have been described above, the plating solution of the present invention may contain various other additives. Furthermore, one or two additives may also serve as functional agents that provide multiple effects. For example, one or two inorganic acids such as sulfuric acid or phosphoric acid, organic acids such as carboxylic acids or sulfonic acids, bases such as ammonia, or salts thereof may be used to provide various functions, such as conductivity, pH adjustment, buffering, and hydrogen generation inhibition. The present invention also encompasses plating solutions for forming Ni—Cr—(Mo / W)-based alloy films that contain inorganic acid salts and / or organic acid salts.

[0049] <Preparation of Plating Solution> The plating solution of this embodiment can be prepared from the components described above using a conventional method, and the details may be determined appropriately taking into consideration the composition and amount of each component, etc. Here, in order to make the complexing agent in the plating solution function more effectively, the plating solution may be subjected to pH adjustment or "aging" treatment before use.

[0050] 2. Method for Forming Alloy Film By performing a plating process using the plating solution of the various embodiments described above, it is possible to form a desired Ni—Cr—(Mo / W) alloy film on various substrates. Therefore, the method for forming a Ni—Cr—(Mo / W) alloy film can be defined as a method including a step of performing a plating process using the plating solution described above. According to such a method, it is possible to form a nickel-based alloy film with excellent throwing power and uniform composition and film thickness.

[0051] There are no particular limitations on the method and conditions for plating, and general electrolytic plating may be carried out under conventional conditions depending on the type of nickel-based alloy film to be formed and the substrate to be plated.

[0052] Specifically, the temperature of the plating solution can be set to about 10 to 90°C, and the current density can be set to 0.01 to 50 A / dm ２ It can be about.

[0053] <Outline of Plating Treatment> A nickel-based alloy coating can be formed by, for example, immersing an object to be plated as a cathode together with an anode in the plating solution of the present invention and passing a current through it. Here, if the solution temperature is 10°C or higher and the current density is 0.01 A / dm ２ If the solution temperature is 90°C or less, changes in concentration, etc. due to evaporation or boiling of the plating solution are suppressed, making it easier to form a nickel-based alloy film with a more uniform composition and film thickness. ２ If the temperature is below this range, defects such as scorching in the resulting alloy film can be easily suppressed. Note that although the plating solution in the plating tank is sometimes called a "plating bath," in this embodiment, both are considered to be the same and are referred to as a "plating solution."

[0054] (Object to be plated) Here, the object to be plated in this embodiment may be any material as long as it is conductive, and may include, of course, various metal materials and conductive ceramic materials, as well as non-conductive ceramics, glass, carbon materials, resins, rubber, wood, and other non-conductors that have been made conductive by, for example, electroless plating or metal vapor deposition. When plating conductive materials such as metals, a material having another plating layer applied to the substrate may also be used. There are also no particular limitations on the shape of the object to be plated.

[0055] Considering the excellent heat resistance and corrosion resistance of Ni—Cr—(Mo / W) alloys, including Hastelloy, the alloy coating method of this embodiment can be particularly effective when the object to be plated is a heat-resistant or corrosion-resistant material. For example, by forming a Ni—Cr—(Mo / W) alloy coating on a substrate made of iron or stainless steel, or on such a substrate plated with chrome or nickel, a material with particularly excellent heat resistance and corrosion resistance can be obtained. Depending on the intended use temperature, a metal layer or the like may be formed in advance by electroless plating or the like on the surface of a heat-resistant resin material, such as a thermoset polyimide or its fiber composite, and then subjected to the plating process of this embodiment. Polymer materials treated by the plating method of this embodiment can be used as lightweight, corrosion-resistant materials.

[0056] (Anode) There is no particular limitation on the anode used in the plating process. For example, an electrode made of nickel or a nickel-based alloy may be used as the anode, and nickel, or even chromium or molybdenum, etc. may be supplied into the plating solution during the process. However, in order to stably proceed with the plating process and form a more uniform alloy film, it is preferable to use an electrode based on an insoluble material, such as iridium oxide, tantalum oxide, platinum, lead, lead alloy, boron-doped diamond, graphite, etc. as the anode. These anodes do not dissolve in the plating solution during the process, or dissolve only slightly, so there is no risk of changing the composition of the plating solution, and as a result, it is easier to form an alloy film with a more uniform composition.

[0057] <Practical Plating Treatment> The plating treatment for forming a nickel-based alloy film on various conductive or non-conductive substrates will be described in more detail below.

[0058] (Pretreatment) Prior to the plating treatment of this embodiment, the substrate to be plated may be subjected to pretreatment, such as degreasing or acid activation treatment. In particular, when plating non-conductors such as general ceramics or resins, it is desirable to perform pretreatment such as electroless plating, sputtering, or vapor deposition in advance to form a metal layer or graphite layer on the surface to impart conductivity.

[0059] The pretreatment method is not particularly limited, and a desired method can be used depending on the substrate to be used, etc. To explain a more specific embodiment using a case where a nonconductor is subjected to a general electroless plating treatment as an example, for example, the surface to be treated of the substrate is optionally degreased and cleaned, then subjected to an etching treatment, and then brought into contact with a catalyst-imparting enhancing liquid (conditioning). Next, a catalyst such as palladium is imparted to the surface by contact with a catalyst-imparting treatment liquid, and the catalyst is then optionally activated with an inorganic acid, a reducing agent, or the like, and electroless nickel plating, electroless copper plating, electroless cobalt plating, or the like is carried out.

[0060] The substrate after electroless plating may be further subjected to strike plating treatment such as copper strike plating, nickel strike plating, silver strike plating, or gold strike plating; or general-purpose plating treatment such as nickel plating, chrome plating, nickel chrome plating, tin plating, tin silver plating, copper plating, gold plating, or silver plating.

[0061] When the substrate is made of a conductive material such as a metal or conductive ceramic, the substrate may be subjected to the above-mentioned degreasing, etching, strike plating, general-purpose plating, etc., if desired.

[0062] (Plating Treatment Procedure) The optionally pretreated object (substrate) is subjected to plating treatment in the plating solution of the present invention. In the plating treatment, the solution temperature is set to 10 to 90°C and the current density is set to 0.01 to 50 A / dm as described above. ２ More preferably, the liquid temperature is 20 to 80°C, particularly 25 to 70°C, and the current density is 0.1 to 20 A / dm ２ , especially 1 to 10 A / dm ２ The plating time may be appropriately set depending on the type of nickel-based alloy film to be formed, the solution temperature during the treatment, and the current density, but is preferably about 1 to 300 minutes, and particularly about 3 to 120 minutes.

[0063] The appropriate pH of the plating solution during plating varies depending on the type of nickel-based alloy film desired and the composition of the plating solution used, but may be, for example, about 0.5 to 12, particularly about 1 to 6. Plating under these conditions makes it possible to easily form a Ni—Cr—(Mo / W)-based alloy film with excellent uniformity in composition and film thickness, such as a nickel-based alloy film with a Hastelloy-like composition. During plating, it is preferable to agitate the solution by aeration, pump circulation, paddle stirring, or the like.

[0064] (Post-treatment) Plated parts having a nickel-based alloy coating formed thereon as described above may, of course, be used as is, or an electrolytic chemical conversion coating and / or an immersion chemical conversion coating may be applied to the alloy coating. Ni—Cr—(Mo / W)-based alloy coatings generally have excellent heat resistance and corrosion resistance, but the corrosion resistance of plated parts can be further enhanced by applying a treatment film. There are no particular restrictions on the electrolytic chemical conversion coating and immersion chemical conversion coating, and conventional treatment methods can be applied as desired. Examples include, but are not limited to, chromate treatment, wax treatment, treatment with a solution of benzotriazole or triazine thiol, treatment with a solution of a compound having an amino group or an imino group, anodizing, and heat treatment.

[0065] 3. Plated Parts>>By using the plating method of the present embodiment as described above, it is possible to form a Ni—Cr—(Mo / W)-based alloy coating having excellent uniformity in composition and film thickness on various substrates. Hereinafter, embodiments relating to plated parts produced using the plating solution and plated parts produced by the plating method will be described.

[0066] The plated part of this embodiment exhibits excellent heat resistance and corrosion resistance due to the Ni—Cr—(Mo / W) alloy coating. Furthermore, any material can be used as the substrate. Therefore, for example, using a material with relatively good workability, such as iron or stainless steel, as the substrate, it is possible to produce plated parts with complex and fine shapes that are simultaneously excellent in heat resistance and corrosion resistance and are also low-cost. Lightweight, corrosion-resistant materials can also be produced by plating various shapes of polymeric materials, particularly heat-resistant polymeric materials based on polyimide or the like. The present invention provides a variety of plated parts with excellent heat resistance and corrosion resistance, such as industrial materials, automobile parts, building materials, home appliance parts, and electronic parts, in various shapes.

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way.

[0068] Example 1 A plating solution was prepared by adding sulfuric acid and an aqueous solution of sodium hydroxide to a chemical solution (aqueous solution) having the following composition to adjust the pH to 2.5. A copper disk (diameter 36 mm, surface area of ​​one side 0.1 dm²) that had been degreased and then acid-activated was placed in this plating solution. ２ ) and IrO ２ / Ti as anode, 50°C, 6 A / dm ２ The plating process was carried out for 6 minutes under the conditions of (a) to (b) to obtain plated part samples. The obtained samples exhibited good appearance. The Ni, Cr, and Mo contents (mass%) and film thicknesses were measured for the disk samples at the center and four end points (four points near each vertex of a square inscribed in the circle). The contents and film thicknesses of each metal were measured using the fluorescent X-ray FP method. The measurement results are shown in Table 1 below.

[0069] [Composition of chemical solution in Example 1] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ MoO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L Na ２ SO ４1.0 mol / L・H ３ BO ３ 1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0070] Example 2 The plating time was changed to 20 minutes, and the same operation as in Example 1 was carried out. The measurement results are shown in Table 1.

[0071]

[0072] In both Examples 1 and 2, nickel-based alloy coatings with little variation in composition and film thickness depending on the measurement location and with good appearance were obtained.

[0073] Example 3 A copper plate (a Hull Cell copper plate measuring 67 mm long x 100 mm wide) that had been degreased and then acid-activated was immersed as a cathode in a plating solution having the same composition as that used in Example 1, and IrO ２ A Hull cell test was conducted using a Ti / Ti anode. The test was conducted for 5 minutes with the pH of the plating solution adjusted to 2.5, the solution temperature at 50°C, and a current value of 3 A, as in Example 1. The width (thickness around 100 mm at maximum) of the region where the plating film was formed (ranging from the low current density side to the high current density side) and the average film thickness of the plating film at each current density based on the Hull cell test are shown in Table 2 below, and the content of each metal element is shown in Table 3 below.

[0074] Examples 4 to 6, Comparative Example 1 Tests were conducted in the same manner as in Example 3, except that the amount of complexing agent (gluconic acid) relative to the total amount of metal ion sources was 0.10 equivalents, 0.50 equivalents, or 1.88 equivalents (Examples 4 to 6), or 3.0 equivalents (Comparative Example 1). The results of the throwing power and film thickness measurements are shown in Table 2, and the content of each metal element in Example 6 is shown in Table 3.

[0075] Comparative Examples 2 to 4 The same operation as in Example 3 was carried out, except that chemical solutions (aqueous solutions) of the following compositions were used and Ni anodes were used. The pH of each plating solution was adjusted to 2.8 by adding sulfuric acid and aqueous sodium hydroxide solutions. In Comparative Example 1, larger amounts of sulfuric acid and sodium hydroxide were added during pH adjustment than in the comparative examples. Furthermore, only in Comparative Example 3 was an air flow at a flow rate of 1 L / min used during plating. The results of measuring the throwing power and film thickness are shown in Table 2, and the content of each metal element in Comparative Example 2 is shown in Table 3.

[0076] [Composition of chemical solutions in Comparative Examples 2 to 4] NiCl ２ 0.042mol / L ・CrCl ３ 0.19mol / L ・Na ２ MoO ４ ・2H ２ O 0.17 mol / L Sodium gluconate 0.16 mol / L Formic acid 0.78 mol / L Glycine 0.67 mol / L H ３ BO ３ 0.29 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 4.0 equivalents

[0077]

[0078]

[0079] In Examples 3 to 6, in which the amount of complexing agent relative to the total amount of metal ion source was 0.10 to 1.88, good results were obtained, with throwing weights of 87 mm or more. In these Examples, scorching and discoloration were hardly observed, and in particular in Example 5, in which the amount was 0.50, and Example 3, in which the amount was 0.88, plating films with thicknesses generally exceeding 0.05 μm were formed. Furthermore, in Examples 3 and 6, the current density was 4 A / dm ２ In the above cases, the chromium content in the plated film was 10 mass % or more. On the other hand, in Comparative Examples 1 to 4, in which the amount of complexing agent relative to the total amount of metal ion source was large at 3.0 to 4.0, the plated film thickness was generally thin. In particular, in Comparative Examples 2 to 4, the throwing power was poor at 45 mm or less, and the current density was 5 A / dm ２In Comparative Examples 1 to 4, there was a strong tendency for scorching and discoloration to occur at high current densities. It was revealed that, according to the present invention, by adjusting the amount of complexing agent to within the range of 0.01 to 2 equivalents, a plating solution with excellent throwing power can be obtained.

[0080] Example 7 The same test as in Example 2 was carried out, except that a chemical solution (aqueous solution) having the following composition was used to prepare the plating solution. A Ni-Cr-W alloy (Ni:Cr:W ≈ 8:1:1) coating with good appearance was formed.

[0081] [Composition of chemical solution in Example 7] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ WO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L Na ２ SO ４ 1.0 mol / L・H ３ BO ３ 1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0082] Example 8 The same test as in Example 2 was carried out, except that a chemical solution (aqueous solution) having the following composition was used to prepare the plating solution. A Ni-Cr-Mo-W alloy (Ni:Cr:Mo:W ≈ 5:1:1:3) coating with good appearance was formed.

[0083] [Composition of chemical solution in Example 8] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ MoO ４ ・2H ２ O 0.02mol / L ・Na ２ WO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L Na ２ SO４ 1.0 mol / L・H ３ BO ３ 1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.83 equivalents

[0084] Comparative Example 5 The same operation as in Comparative Example 4 was carried out, except that NaCl was added as a conductive salt to a concentration of 1.00 mol / L. A good plating film was not formed, and the throwing power was 39 mm.

[0085] Reference Example 1: Copper disks were plated in the same manner as in Example 2 (Ni:Cr:Mo ≈ 8:1:1), and the resulting plated samples were immersed in (1 + 1) hydrochloric acid for 3 minutes or in (1 + 1) nitric acid for 0.5 minutes to perform corrosion resistance tests. Similar procedures were also performed on samples obtained by plating the same copper disks with bright nickel, hexavalent chromium, Ni—Cr (8:2) alloy, and Ni—Mo (5.5:4.5) alloy, as well as the sample obtained in Example 7 (Ni:Cr:W ≈ 8:1:1) and the sample obtained in Example 8 (Ni:Cr:Mo:W ≈ 5:1:1:3). A photograph of the appearance after the test is shown in Figure 1.

[0086] Unlike plated part samples having Ni-Cr-(Mo / W) alloy coatings or Ni-Mo alloy coatings, the appearance of the plated part samples having Ni-Cr-(Mo / W) alloy coatings according to the present invention showed almost no change after immersion in hydrochloric acid or nitric acid, demonstrating the high corrosion resistance of the Ni-Cr-(Mo / W) alloy coating.

[0087] As described above, the present invention provides a plating solution and a plating method that have excellent throwing power and are capable of forming a Ni-Cr-(Mo / W)-based alloy film with a more uniform composition and film thickness. According to the present invention, it is possible to form a nickel-based alloy film with a composition such as Hastelloy on the surface of components of various shapes and materials with a uniform composition and film thickness, thereby producing plated parts that are lightweight and low-cost, yet have excellent heat resistance and corrosion resistance.

Claims

1. A plating solution for forming a Ni—Cr—(Mo / W) alloy film, which contains a metal ion source including an ion source of nickel, chromium, and molybdenum and / or tungsten, and a complexing agent, wherein the amount of the complexing agent relative to the total amount of the metal ion source is 0.01 equivalent or more and 2 equivalents or less.

2. The plating solution according to claim 1, further containing a conductive salt.

3. The plating solution according to claim 2, wherein the conductive salt contains a sulfate.

4. The plating solution according to claim 1, further containing a pH adjuster containing a hydroxide of an alkali metal.

5. The plating solution according to claim 1, wherein the complexing agent is one or more selected from the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylates, amino acids, amino acid salts, and alcohols.

6. The plating solution according to claim 1, further containing a pH buffer.

7. The plating solution according to claim 1, wherein the concentration of nickel is in the range of 0.001 to 0.5 mol / L in terms of element, the concentration of chromium is in the range of 0.01 to 1.5 mol / L in terms of element, and the total concentration of molybdenum and tungsten is in the range of 0.001 to 2.0 mol / L in terms of element.

8. A method for forming a Ni—Cr—(Mo / W) alloy film, which includes a step of plating using the plating solution according to any one of claims 1 to 7.

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