Nickel-based alloy plating solution

Abstract

To provide a plating solution and a plating method, having excellent uniform electrodeposition properties and enabling formation of a Ni-Cr-(Mo / W)-based alloy film with more uniform composition and thickness.SOLUTION: Provided is a plating solution for forming a Ni-Cr-(Mo / W)-based alloy film, containing metal ion sources that include ion sources of nickel, chromium, and molybdenum and / or tungsten, and a complexing agent, where the amount of the complexing agent relative to the total amount of the metal ion sources is 0.01 to 2 equivalents inclusive. Also provided is a method for forming a Ni-Cr-(Mo / W)-based alloy film, including a step of performing plating with the use of the plating solution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a plating solution for forming nickel-based alloy films. [Background technology]

[0002] Nickel-based alloys, including Hastelloy (registered trademark), have long been widely used as heat-resistant and corrosion-resistant materials. These nickel-based alloys have excellent heat and corrosion resistance, exhibit high durability against halogens and various oxidizing and non-oxidizing chemical substances, are resistant to pitting and crevice corrosion, and are also highly resistant to stress corrosion cracking.

[0003] Due to these advantages, nickel alloys can be used in high-temperature and corrosive environments, but they also have the disadvantage of being hard and difficult to shape. Therefore, materials made from nickel alloys tend to be expensive, as they are difficult to process into complex shapes and the material itself is expensive. Nickel alloys also have a relatively high specific gravity, which makes it difficult to reduce the weight of the material.

[0004] If nickel-based alloys can be applied to various materials in the form of a surface coating, the difficulties in formability can be overcome, and cost reduction and weight reduction can be easily achieved. 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 plating method for alloys using a plating bath containing chromium ions, nickel and / or cobalt ions, and tungstic acid, molybdic acid, and / or rhenium acid ions, each at specific concentrations. Patent Document 2 discloses a plating solution with a pH of 8 to 11, in which a gluconate salt is selected as a complexing agent for nickel-based alloy plating and is combined with a nickel salt and a molybdate salt to improve the efficiency and appearance of the plating film formation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-302496 [Patent Document 2] Japanese Patent Publication No. 2005-082856 [Overview of the project] [Problems that the invention aims to solve]

[0007] Conventional methods as described above do not necessarily yield a uniform nickel-based alloy plating film with excellent corrosion resistance. For example, in the plating method described in Patent Document 1, as shown in the examples below, uniform electrodeposition of the nickel-chromium-molybdenum alloy film is difficult. Similar problems can occur with the plating solution described in Patent Document 2, which involves consideration of the type of complexing agent. Furthermore, the nickel-molybdenum alloy plating solution described in Patent Document 2 does not contain chromium ions, making it difficult to achieve sufficient acid resistance. Simply adding a chromium salt to this plating solution does not necessarily yield a uniform plating film with a good appearance.

[0008] The present invention aims to solve the above-mentioned problems by providing a plating solution that exhibits excellent uniform electrodeposition properties and can form nickel-chromium-molybdenum and / or tungsten alloy films with a more uniform composition and film thickness, as well as a method for forming a plated film using the plating solution. [Means for solving the problem]

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

[0010] In other words, the present invention provides the following (1) to (8). (1) A plating solution for forming a Ni-Cr-(Mo / W) alloy film, comprising a metal ion source containing nickel, chromium, and molybdenum and / or tungsten ion sources, 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) further comprising a conductive salt. (3) The plating solution of (2), wherein the conductive salt contains a sulfate. (4) A plating solution according to any of (1) to (3) above, further comprising a pH adjuster containing an alkali metal hydroxide. (5) A plating solution according to any of (1) to (4) above, 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) A plating solution according to any of the above (1) to (5), further containing a pH buffer. (7) Any of the plating solutions (1) to (6) above, wherein the nickel concentration is in the range of 0.001 to 0.5 mol / L on an elemental basis, the chromium concentration is in the range of 0.01 to 1.5 mol / L on an elemental basis, and the total concentration of molybdenum and tungsten is in the range of 0.001 to 2.0 mol / L on an elemental basis. (8) A method for forming a Ni-Cr-(Mo / W) alloy film, comprising the step of plating using any of the plating solutions described in (1) to (7) above. [Effects of the Invention]

[0011] The plating solution of the present invention exhibits excellent uniform electrodeposition properties, and according to the plating solution and method of the present invention, Ni-Cr-(Mo / W) alloy films can be formed without large variations in composition or film thickness. [Brief explanation of the drawing]

[0012] [Figure 1] This photographic diagram shows the results of corrosion resistance tests (Reference Example 1) on plated part samples obtained in Examples 2, 7, and 8 according to the present invention, along with the results for other plated part samples. [MODES FOR CARRYING OUT THE INVENTION]

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

[0014] <<1. Plating Solution>> The plating solution according to the present embodiment is a plating solution for forming a Ni-Cr-(Mo / W) alloy film, which contains a metal ion source including ion sources of nickel, chromium, and molybdenum and / or tungsten, and a complexing agent. 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.

[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] Examples of these ion sources generally include nickel salts, chromium salts, various chromates, molybdenum salts, various molybdates, tungsten salts, and various tungstates, and these can also be used in the present embodiment. It is also possible to use a combination of multiple types of ion sources of the same metal, for example, a chromium salt and a chromate. Further, a salt such as nickel molybdate can also be used. In addition to these, complex ion salts such as ammonium complexes and cyano complexes of various metal ions may be used. However, in order to optimize the content ratio with the complexing agent, which is another essential component, and form a plating film having a uniform composition and film thickness, it is preferable to use a non-complex metal salt or metal acid salt as the metal ion source.

[0017] More preferred metal ion sources are nickel salts, chromium salts, molybdates, and tungstates. Among these, halides, sulfates, sulfites, nitrates, nitrites, perchlorates of nickel and chromium, and sodium salts, potassium salts, and ammonium salts of molybdic acid and tungstic acid are preferred. In particular, nickel sulfate, chromium sulfate, basic chromium sulfate, ammonium molybdate, and ammonium tungstate are suitable as the metal ion source in the present embodiment. A plating solution containing these metal ion sources can form a highly corrosion-resistant Ni-Cr-(Mo / W) alloy film with a more uniform composition and thickness.

[0018] As the metal ion source, ion sources of other metals such as iron (Fe), cobalt (Co), manganese (Mn), copper (Cu), titanium (Ti), niobium (Nb), and aluminum (Al) may be further contained. When such ion sources of other metals are used in combination, for example, Hastelloy containing small amounts of Mn, Co, etc. in a Ni-Cr-Mo-Fe system (Registered trademark) X, and further Inconel (INCONEL), Incoloy (INCOLOY), Waspaloy, DSALOY a nickel-based alloy film having a composition such as those of (registered trademark) can also be formed. If desired, phosphate, silicate, or the like may be used in combination to obtain a plating solution for a nickel-based alloy film containing phosphorus (P) or silicon (Si). According to the plating solution of the present embodiment, it may also be possible to form an alloy film having a composition that cannot be produced by metallurgical methods.

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

[0020] Specifically, complexing agents include, but are not limited to, cyanides; various carboxylic acids and their salts; various amino acids and their salts; phosphorus-containing compounds such as pyrophosphates, nitrilotrimethylphosphonic acid and its salts, and tris(3-hydroxypropyl)phosphine; thiourea, thioglycolic acid, thiodiglycolic acid, thioglycol, thiodiglycolic acid, 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, thiosulfates, and other sulfur-containing compounds; and alcohols; as well as ethylenediamine, ascorbic acid, gluconolactone, glucoheptonolactone, etc. It was also possible to use multiple types of complexing agents in combination.

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

[0022] (Carboxylic acids and their salts) Suitable carboxylic acids 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. Suitable carboxylic acid salts include sodium salts, potassium salts, and ammonium salts of these compounds. Salts of carboxylic acids having multiple carboxyl groups may also be double salts in which only some of the carboxyl groups form the salt, such as sodium hydrogen oxalate or potassium sodium oxalate.

[0023] (Hydroxycarboxylic acids and their salts) Suitable hydroxycarboxylic acids as complexing agents include glycolic acid, gluconic acid, citric acid, glucoheptonic acid, tartaric acid, and diglycolic acid. Suitable hydroxycarboxylic acid salts include their sodium salts, potassium salts, and ammonium salts. For example, sodium bitartrate or potassium sodium tartrate may also be used.

[0024] (Amino acids and their salts) Suitable amino acids (aminocarboxylic acids) 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. Suitable amino acid salts include sodium salts, potassium salts, and ammonium salts of these amino acids.

[0025] (alcohol) Suitable alcohols as complexing agents include, for example, ethylene glycol, propylene glycol, diethylene glycol, and other glycols.

[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 source is between 0.01 equivalents and 2 equivalents. 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 uniform electrodeposition properties of the plating solution are improved, making it possible to form nickel-based alloy films with a more uniform composition and film thickness.

[0027] In general, alloy plating uses multiple metals with different deposition potentials, and to form a desired alloy film with a uniform composition, complexing agents are often used in amounts exceeding the amount of metal ion source. For example, in the case described in Patent Document 1, multiple types of organic acids are used as complexing agents in a total amount of more than 2 equivalents to about 4 equivalents relative to the total molar amount of metal ions. In the nickel-molybdenum alloy plating solution described in Patent Document 2, if 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 it decreases significantly, especially below 1 equivalent. In this study, when forming plating films of nickel, chromium, and molybdenum and / or tungsten alloys (Ni-Cr-(Mo / W) alloys), an unexpected effect was observed: by using a small amount of complexing agent, 0.01 to 2 equivalents relative to the total amount of metal ion source, a plating solution with excellent uniform electrodeposition properties was obtained.

[0028] Here, "equivalent amount" refers to the ratio of the molar amount of complexing agent molecules to the total molar amount of metal ions constituting the plating film.

[0029] Furthermore, "total amount of metal ion source" refers to the total molar amount 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 molybdate salts. Generally, it refers to the total molar amount of Group 3 to Group 15 metals in the plating solution, for example, Group 4 to Group 14 metals.

[0030] Furthermore, the "molar amount of metal ion source" is a value based on the metal element. For example, if the plating solution contains 0.1 moles of Cr2(SO4)3, the amount of chromium ion source is calculated as 0.2 moles.

[0031] (Concentration of metal components) In relation to the amount of the metal ion source, the concentrations of each metal component can also be explained. The concentrations of the metal components in the plating solution of this embodiment can be arbitrarily set according to the type of plating film to be used and the conditions of the plating process. For example, the concentration of nickel may be set to 0.001 to 0.5 mol / L in elemental terms, the concentration of chromium to 0.01 to 1.5 mol / L in elemental terms, and the total concentration of molybdenum and tungsten to 0.001 to 2.0 mol / L in elemental terms.

[0032] Alternatively, the concentrations of these metal components may be set as follows, on an elemental basis: nickel concentration of 0.001-0.5 mol / L, particularly 0.01-0.1 mol / L; chromium concentration of 0.01-1.5 mol / L, particularly 0.1-1.0 mol / L; and molybdenum concentration of 0.001-2.0 mol / L, particularly 0.01-1.0 mol / L. Tungsten may be added as desired, either in place of or in addition to molybdenum, at a concentration of approximately 0.001-2.0 mol / L, particularly 0.01-1.0 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 source, i.e., the molar ratio of complexing agent amount / total amount of metal ion source, is set to 0.01 equivalents or more and 2 equivalents or less. Preferably, the molar ratio of complexing agent amount / total amount of metal ion source 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 same molar ratio may also be set to 1.5 equivalents or less, more preferably 1.0 equivalent or less, particularly preferably 0.90 equivalents or less, and further to 0.8 equivalents or less, or 0.6 equivalents or less, for example, 0.10 to 2.0 equivalents, especially 0.20 to 1.5 equivalents, even more preferably 0.30 to 1.0 equivalents, and particularly 0.40 to 0.90 equivalents.

[0034] By appropriately selecting the molar ratio of the amount of complexing agent to the total amount of the metal ion source from within the range of 0.01 to 2, depending on the type of plating film and complexing agent, a nickel-based alloy film can be formed with an even more uniform composition and film thickness. The concentration of the complexing agent in the plating solution is mainly determined based on the total concentration of the metal ion source, but it is generally preferable to set it to around 0.01 to 1 mol / L, and particularly around 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 it may also contain organic solvents such as alcohols like methanol and ethanol; ethers like tetrahydrofuran (THF), dioxane, and various glimes; carbonate esters like ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; nitrogen-containing solvents like acetonitrile, dimethylformamide (DMF), and pyrrolidone; and sulfur-containing solvents like dimethyl sulfoxide (DMSO). Depending on the purpose and the type of metal salt and complexing agent used, an organic solvent may also be used as the main solvent.

[0036] <Additives> The plating solution of this embodiment may contain various additives, including conductive salts and other conductivity-imparting agents, pH adjusters, pH buffers, hydrogen generation inhibitors, dispersants, dispersion aids, emulsifiers, surfactants, brighteners, antioxidants, viscosity modifiers, wetting agents, and dyes, along with a metal ion source and complexing agent. In particular, the addition of conductive salts, pH adjusters, and pH buffers can further improve the uniform electrodeposition properties of the plating solution. Some of these additives will be described below.

[0037] (Conductive salt) There are no particular restrictions on the type of conductive salt; 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. If the plating solution contains sulfates or ammonium salts as conductive salts, the deposition of the metal that forms the target film is promoted in a balanced manner, making it easier to form an alloy plating with a 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 are no particular restrictions on the concentration of these conductive salts in the plating solution, and it can be set to any desired value depending on the concentration of the metal component, etc. For example, a concentration of 0.1 to 3 mol / L, particularly 0.25 to 2 mol / L, may be used, but it is not limited to this range.

[0039] (pH adjuster) The plating solution of this embodiment may contain a pH adjusting agent to further improve uniform electrodeposition, and the pH may be adjusted to a range suitable for nickel alloy plating, for example, 0.5 to 12, particularly 0.5 to 10, even more specifically 0.5 to 7.5, and especially 1 to 6.

[0040] pH adjusters are also useful because they allow complexing agents to function effectively. Each complexing agent has a pH at which it is most 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 an operation called "aging," in which it is maintained at a specific temperature and pH for a certain period of time. It is preferable to use a pH adjuster during such operations.

[0041] There are no particular restrictions on the pH adjusting agent added to the plating solution in this embodiment, and various acids and / or bases can be used depending on the pH during the desired plating process or maturation. In this case, using a pH adjusting agent containing sulfuric acid as the acid, or using a pH adjusting agent containing alkali metal hydroxide and / or ammonia as the base, has the advantage of improving the conductivity of the plating solution, which is preferable.

[0042] (pH buffering agent) The plating solution of this embodiment preferably further contains a pH buffer to stabilize the deposition reaction of the target metal. While a pH buffer can be considered a type of pH adjuster in a broad sense, it is treated here as a component distinct from a pH adjuster in a narrow sense. There are no particular restrictions on the type of pH buffer; 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 their salts.

[0043] (Hydrogen generation inhibitor) The plating solution of this embodiment may also contain a hydrogen generation inhibitor. Including a hydrogen generation inhibitor in the plating solution makes it easier to suppress a decrease in current efficiency during the plating process. Furthermore, suppressing the generation of hydrogen gas at the cathode makes it easier to prevent charring and hydrogen embrittlement of the plating film. Charring (burning) refers to a problem where the current density at the cathode becomes excessive, resulting in the formation of a rough and brittle plating film. This phenomenon is caused by the deposition of metal hydroxides due to an increase in pH at the cathode interface. There are no particular restrictions on the hydrogen generation inhibitor; various known ones can be used. For example, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and their salts can be used, with boric acid, citric acid, or their salts being particularly preferred.

[0044] When a hydrogen generation inhibitor is included, its concentration is preferably around 0.01 to 2.0 mol / L, and particularly preferably around 0.1 to 1.5 mol / L. Furthermore, some of these hydrogen generation inhibitors can also function as the complexing agents and pH buffering agents mentioned above. Therefore, by setting the concentration of citric acid in the plating solution to, for example, 0.01 to 2.0 mol / L, and even further to 0.02 to 1.5 mol / L, and particularly to 0.10 to 1.0 mol / L, it is possible to achieve all the functions of complex formation, pH adjustment, and hydrogen generation inhibition.

[0045] (Gloss agent) The plating solution of this embodiment may contain a brightener. The brightener may not only impart gloss to the plating film but also promote the deposition of metal in recesses and flatten the plating surface. There are no particular restrictions on the type of brightener; various aldehydes, triazines, imidazoles, indoles, quinolines, 2-vinylpyridines, anilines, phenanthroline, neocuproin, picolinic acid, thioureas, benzothiazoles, sulfides, etc., can be used. If a brightener is included, 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] (Surfactants) There are no particular restrictions on the surfactant used; any desired surfactant can be selected from ordinary anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. If a surfactant is included, its concentration is preferably around 1 mg / L to 50 g / L, and particularly preferably around 5 mg / L to 10 g / L.

[0047] (Antioxidant) Antioxidants are used to prevent the oxidation of metal salts. Examples of antioxidants include, but are not limited to, hypophosphorous acids, ascorbic acid, phenolsulfonic acid, cresolsulfonic acid, hydroquinonesulfonic acid, hydroquinone, α or β-naphthol, catechol, resorcinol, phloroglucin, hydrazine, phenolsulfonic acid, catecholsulfonic acid, hydroxybenzenesulfonic acid, naphtholsulfonic acid, and their salts. Antioxidants can be included in concentrations of approximately 0.1 g / L to 500 g / L, particularly 1 g / L to 100 g / L.

[0048] The above describes some representative additives, but the plating solution of the present invention may contain various other additives. Furthermore, one or two additives can also be used as functional agents that provide multiple effects. For example, one or two types of 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 exhibit various functions such as imparting conductivity, adjusting pH, buffering, and inhibiting hydrogen generation. The present invention also includes plating solutions for forming Ni-Cr-(Mo / W) alloy films that contain inorganic and / or organic acid salts.

[0049] <Preparation of plating solution> The plating solution of this embodiment can be prepared using conventional methods from the above-mentioned components, and the details can be appropriately determined by considering the composition and amount of each component. In order to make the complexing agent in the plating solution function more effectively, pH adjustment and "aging" treatment may be performed before use.

[0050] ≪2. Method for forming alloy coating≫ By performing a plating treatment using the plating solutions of the various embodiments described above, a desired Ni-Cr-(Mo / W) alloy film can be formed on various substrates. Therefore, a method for forming a Ni-Cr-(Mo / W) alloy film can be defined as a method that includes the step of performing a plating treatment using the plating solution described above. With such a method, a nickel-based alloy film with excellent uniform electrodeposition properties and uniform composition and film thickness can be formed.

[0051] There are no particular restrictions on the plating method and conditions; depending on the type of nickel-based alloy film to be plated and the substrate to be plated, for example, general electroplating can be performed under conventional conditions.

[0052] Specifically, the temperature of the plating solution can be set to approximately 10-90°C. The current density can be 0.01-50 A / dm². 2 It can be considered to be of a certain degree.

[0053] <Overview of Plating Process> A nickel-based alloy coating can be formed, for example, by immersing the object to be plated as the cathode, along with the anode, in the plating solution of the present invention and applying an electric current. Here, the solution temperature must be 10°C or higher, and the current density must be 0.01 A / dm². 2 If the above conditions are met, it becomes easier to form a nickel-based alloy film in a relatively short time. If the liquid temperature is 90°C or lower, changes in concentration due to evaporation or boiling of the plating solution are suppressed, resulting in the formation of a nickel-based alloy film with a more uniform composition and film thickness. Also, if the current density is 50 A / dm² 2 The following conditions make it easier to suppress defects such as charring in the resulting alloy film. Note that while the plating solution in the plating tank is sometimes referred to as the "plating bath," in this embodiment, both are treated as the same and referred to as the "plating solution."

[0054] (Object to be plated) In this embodiment, the object to be plated can be anything as long as it is conductive. This includes various metal materials and conductive ceramic materials, as well as non-conductive materials such as non-conductive ceramics, glass, carbon materials, resins, rubber, and wood, which can be made conductive by, for example, electroless plating or metal vapor deposition. When plating conductive materials such as metals, materials with other plating layers attached to the substrate can also be used. There are no particular restrictions 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 film formation 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 film on a substrate made of iron or stainless steel, or on a substrate made of these materials that has been plated with chromium or nickel, a material with particularly excellent heat resistance and corrosion resistance can be obtained. Depending on the intended operating temperature, a metal layer may be formed in advance on the surface of a heat-resistant resin material, such as a thermoset polyimide or its fiber composite material, by electroless plating, and then subjected to the plating treatment of this embodiment. Polymer materials treated by the plating method of this embodiment can be used as lightweight corrosion-resistant materials.

[0056] (anode) There are no particular restrictions on the anode used in the plating process. For example, electrodes made of nickel or nickel-based alloys may be used as the anode, and nickel, as well as chromium and molybdenum, may be supplied to the plating solution during the process. However, in order to ensure a stable plating process and to form a more uniform alloy film, it is preferable to use electrodes based on insoluble materials, such as iridium oxide, tantalum oxide, platinum, lead, lead alloy, boron-doped diamond, or graphite, as the anode. These anodes do not dissolve into the plating solution during the process, or only dissolve in small amounts, so there is no risk of changing the composition of the plating solution, and as a result, it becomes easier to form an alloy film with a more uniform composition.

[0057] <Practical aspects of plating> The following section provides a more detailed explanation of the plating process for forming nickel-based alloy films on various conductive and non-conductive substrates.

[0058] (Pre-processing) Prior to applying the plating process of this embodiment, the substrate to be plated may undergo pretreatment, such as degreasing or acid activation. In particular, when plating insulators such as common ceramics or resins, it is desirable to perform pretreatment such as electroless plating, sputtering, or vapor deposition beforehand to form a metal layer or graphite layer on the surface and impart conductivity.

[0059] There are no particular restrictions on the pretreatment method, and any desired method can be used depending on the substrate used. To give a more specific example, when a non-conductive material is subjected to a general electroless plating process, for example, the surface to be treated of the substrate is optionally degreased and cleaned, then etched, and then brought into contact with a catalyst-enhancing solution (conditioning). Next, a catalyst such as palladium is applied by bringing it into contact with a catalyst-enhancing solution, and then the catalyst is optionally activated with an inorganic acid or reducing agent, and electroless nickel plating, electroless copper plating, electroless cobalt plating, etc., is performed.

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

[0061] Furthermore, if the substrate is a conductive material such as metal or conductive ceramic, degreasing, etching, strike plating, general-purpose plating, etc., as described above may be performed as desired.

[0062] (Plating process) The object to be plated (substrate), which has been optionally pre-treated, is subjected to plating in the plating solution of the present invention. In the plating process, the solution temperature is set to 10-90°C and the current density to 0.01-50 A / dm² as described above. 2It is preferable to have the following characteristics. 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 1-10 A / dm 2 It is best to set it to a certain extent. The plating time should be set appropriately according to the type of nickel-based alloy film to be used, the liquid temperature during processing, and the current density, but it is generally preferable to set it to about 1 to 300 minutes, and especially to about 3 to 120 minutes.

[0063] The appropriate pH of the plating solution during the plating process varies depending on the type of nickel-based alloy film to be produced and the composition of the plating solution used, but it is generally suitable to have a pH of 0.5 to 12, particularly 1 to 6. By performing the plating process under these conditions, a Ni-Cr-(Mo / W) alloy film with excellent uniformity of composition and film thickness, such as a nickel-based alloy film with a composition like Hastelloy, can be easily formed. Furthermore, it is preferable to aerate, pump circulation, or paddle stirring during the plating process.

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

[0065] ≪3. Plated parts≫ The plating method of this embodiment described above allows for the formation of Ni-Cr-(Mo / W) alloy films with excellent uniformity in composition and film thickness on various substrates. The following describes embodiments relating to plated parts manufactured using the above-described plating solution and plated parts manufactured by the above-described plating method.

[0066] The plated parts of this embodiment exhibit excellent heat resistance and corrosion resistance derived from the Ni-Cr-(Mo / W) alloy coating. Furthermore, any material can be used as the base material. For example, it is possible to use materials with relatively good workability, such as iron or stainless steel, as the base material to produce plated parts with complex and fine shapes, while simultaneously having excellent heat resistance and corrosion resistance, and at low cost. It is also possible to produce lightweight, corrosion-resistant materials by plating various shapes of polymer materials, particularly heat-resistant polymer materials based on polyimide. The present invention provides various plated parts with excellent heat resistance and corrosion resistance in various shapes, such as industrial materials, automotive parts, building material parts, home appliance parts, and electronic parts. [Examples]

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

[0068] ≪Example 1≫ A plating solution was prepared by adding sulfuric acid and sodium hydroxide aqueous solution to a chemical solution (aqueous solution) with the following composition to adjust the pH to 2.5. A degreased and acid-activated copper disc (36 mm in diameter, 0.1 dm² on one side) was placed in this plating solution. 2 Immerse the material in the solution, using IrO2 / Ti as the anode, at 50°C and 6 A / dm 2 Plating was performed for 6 minutes under the specified conditions to obtain plated part samples. The obtained samples exhibited a good appearance. For the disc samples, the content (mass%) of Ni, Cr, and Mo, as well as the film thickness, were measured in the central part and at four points on the edges (four locations near each vertex of the square inscribed in the circle). The content and film thickness of each metal were measured by the FP method using X-ray fluorescence. The measurement results are shown in Table 1 below.

[0069] [Composition of the chemical solution in Example 1] NiSO4·6H2O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na₂MoO₄·2H₂O 0.02 mol / L • Gluconic acid 0.30 mol / L • Na2SO4 1.0 mol / L H3BO3 1.0 mol / L Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0070] Example 2 The same procedure as in Example 1 was performed, with a plating time of 20 minutes. The measurement results are shown in Table 1.

[0071] [Table 1]

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

[0073] Example 3 In Example 1, a degreased and acid-activated copper plate (a Hull cell copper plate measuring 67 mm x 100 mm) was immersed as the cathode in a plating solution of the same composition as used in Example 1, and a Hull cell test was performed with IrO2 / Ti as the anode. The test was conducted in the same manner as in Example 1, with the pH of the plating solution adjusted to 2.5, the solution temperature at 50°C, and a current of 3A for 5 minutes. The width of the area where the plating film was formed (spanning from the low current density side to the high current density side) (maximum thickness: 100 mm) and the average 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 4-6, Comparative Example 1 The same tests as in Example 3 were performed, except that the amount of complexing agent (gluconic acid) relative to the total amount of metal ion source was 0.10 equivalents, 0.50 equivalents, or 1.88 equivalents (Examples 4-6), or 3.0 equivalents (Comparative Example 1). The penetration and film thickness measurement results are shown in Table 2, and the content of each metal element in Example 6 is shown in Table 3.

[0075] ≪Comparative Examples 2-4≫ The procedure was the same as in Example 3, except that a chemical solution (aqueous solution) with the following composition was used and a Ni anode was employed. In all cases, the pH of the plating solution was adjusted to 2.8 by adding sulfuric acid and sodium hydroxide aqueous solution. In Comparative Example 1, a larger amount of sulfuric acid and sodium hydroxide was added during pH adjustment compared to the comparative example. In addition, during the plating process, an airflow of 1 L / min was used only in Comparative Example 3. The results of the plate coverage and film thickness measurements are shown in Table 2, and the content of each metal element in Comparative Example 2 is shown in Table 3.

[0076] [Composition of the chemical solutions in Comparative Examples 2-4] NiCl 20.042 mol / L • CrCl 30.19 mol / L Na₂MoO₄·2H₂O 0.17 mol / L Sodium gluconate 0.16 mol / L Formic acid 0.78 mol / L Glycine 0.67 mol / L H3BO3 0.29 mol / L Amount of complexing agent relative to the total amount of metal ion source: 4.0 equivalents

[0077] [Table 2]

[0078] [Table 3]

[0079] In Examples 3 to 6 where the amount of the complexing agent relative to the total amount of the metal ion source was 0.10 to 1.88, throwing power of 87 mm or higher was obtained, which is a good result. In these examples, burning and discoloration hardly occurred, and particularly in Example 5 with 0.50 and Example 3 with 0.88, a plating film having a thickness of more than approximately 0.05 µm was formed. Further, in Examples 3 and 6, the chromium content in the plating film became 10% by mass or more at a current density of 4 A / dm 2 2 or higher. On the other hand, in Comparative Examples 1 to 4 where the amount of the complexing agent relative to the total amount of the metal ion source was as large as 3.0 to 4.0, the plating film thickness was generally thin. Particularly in Comparative Examples 2 to 4, the throwing power was poor at 45 mm or lower, and at a current density of 5 A / dm 2 2 or lower, a plating film was hardly formed. In Comparative Examples 1 to 4, there was also a great tendency for burning and discoloration to occur on the high current density side. According to the present invention, it has been revealed that by setting the amount of the complexing agent within the range of 0.01 to 2 equivalents, a plating solution excellent in 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 for preparing the plating solution. A Ni-Cr-W-based alloy (Ni:Cr:W ≈ 8:1:1) film with good appearance was formed.

[0081] [Composition of chemical solution in Example 7] · NiSO4·6H2O 0.02 mol / L · Basic chromium sulfate 0.30 mol / L · Na2WO4·2H2O 0.02 mol / L · Gluconic acid 0.30 mol / L · Na2SO4 1.0 mol / L · H3BO3 1.0 mol / L : Amount of complexing agent relative to 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 for preparing the plating solution. A Ni-Cr-Mo-W-based alloy (Ni:Cr:Mo:W ≈ 5:1:1:3) film with good appearance was formed.

[0083] [Composition of the chemical solution in Example 8] NiSO4·6H2O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na₂MoO₄·2H₂O 0.02 mol / L Na₂WO₄·2H₂O 0.02 mol / L • Gluconic acid 0.30 mol / L • Na2SO4 1.0 mol / L H3BO3 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 procedure as in Comparative Example 4 was followed, except that NaCl was added as a conductive salt to a concentration of 1.00 mol / L. No good plating film was formed, and the thickness was 39 mm.

[0085] ≪Reference example 1≫ Copper discs 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 (1+1) nitric acid for 0.5 minutes to perform a corrosion resistance test. The same procedure was performed on the same copper discs plated with bright nickel, hexavalent chromium, Ni-Cr(8:2) alloy, and Ni-Mo(5.5:4.5) alloy, as well as on the samples obtained in Example 7 (Ni:Cr:W≈8:1:1) and Example 8 (Ni:Cr:Mo:W≈5:1:1:3). A photograph of the appearance after the test is shown in Figure 1.

[0086] According to the present invention, plated component samples having a Ni-Cr-(Mo / W) alloy coating showed almost no change in appearance after immersion in hydrochloric acid or nitric acid, unlike plated component samples having Ni-Cr or Ni-Mo alloy coatings. This demonstrated 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 exhibit excellent uniform electrodeposition properties and can form Ni-Cr-(Mo / W) alloy films with a more uniform composition and film thickness. According to the present invention, it is possible to form a nickel-based alloy plating film with a composition such as Hastelloy on the surface of various shapes and materials with a uniform composition and film thickness, resulting in plated parts that are lightweight and low-cost while exhibiting excellent heat resistance and corrosion resistance.

Claims

1. A plating solution containing a metal ion source including nickel, chromium, and molybdenum and / or tungsten ion sources, and a complexing agent, 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. A plating solution for forming a Ni-Cr-(Mo / W) alloy film, wherein the nickel concentration is in the range of 0.001 to 0.5 mol / L on an elemental basis, the chromium concentration is in the range of 0.01 to 1.5 mol / L on an elemental basis, and the total concentration of molybdenum and tungsten is in the range of 0.001 to 2.0 mol / L on an elemental basis.

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

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 comprising a pH buffering agent.

7. A method for forming a Ni-Cr-(Mo / W) alloy film, comprising the step of plating using the plating solution described in any one of Claims 1 to 6.

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