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 thickness.SOLUTION: Provided is a plating solution for forming a Ni-Cr-(Mo / W)-based alloy film, comprising: metal ion sources including ion sources of nickel, chromium, and molybdenum and / or tungsten; and one or more chemical species selected from the group consisting of ammonia, amines, and ammonium ions. Also provided is a method for forming a Ni-Cr-(Mo / W)-based alloy film, comprising a step of performing plating with the use of the plating solution. It is preferable that the plating solution further contains a complexing agent in an amount of 0.01 to 4 equivalents inclusive relative to the total amount of the metal ion sources.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] Due to these advantages, nickel-based alloys can be used in high-temperature and corrosive environments, but on the other hand, they have the drawback of being hard and difficult to form. For this reason, materials using nickel-based alloys are difficult to process into complex shapes, and in combination with the high cost of the material itself, they tend to result in high costs. Nickel-based alloys also have a relatively high specific gravity, which has the disadvantage of making it difficult to reduce the weight of materials.

[0004] If a nickel-based alloy can be applied to various materials in the form of a surface film, it is considered that the difficulty in formability will be solved, and cost reduction and weight reduction will also be facilitated. Based on this idea, several attempts have been made to form nickel-based alloy films by plating.

[0005] For example, Patent Document 1 discloses an alloy plating method that uses a plating bath containing chromium ions, nickel and / or cobalt ions, and tungstic acid, molybdic acid, and / or rhenic acid ions each at specific concentrations. In Patent Document 2, in order to improve the formation efficiency and appearance of the plating film, gluconate is selected as a complexing agent for nickel-based alloy plating, and a plating solution with a pH of 8 to 11 blended with this together with a nickel salt and a molybdate is disclosed. [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 a nickel-chromium-molybdenum and / or tungsten alloy film with a more uniform 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, a nickel-based alloy film can be uniformly electrodeposited by including one or more chemical species selected from the group consisting of ammonia, amines, and ammonium ions in the plating solution, thereby completing the present invention.

[0010] In other words, the present invention provides the following (1) to (10). (1) A plating solution for forming a Ni-Cr-(Mo / W) alloy film, comprising a metal ion source including nickel, chromium, and molybdenum and / or tungsten ion sources, and one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ions. (2) The plating solution according to (1), further comprising a complexing agent in an amount of 0.01 equivalents or more and 4 equivalents or less relative to the total amount of the metal ion source. (3) The plating solution according to (1) or (2) above, wherein the chemical species is derived from one or more sources selected from the group consisting of aqueous ammonia, alkylamines, and ammonium salts. (4) A plating solution containing any of the above (1) to (3), further comprising a conductive salt. (5) The plating solution according to (4) above, wherein the conductive salt is a sulfate and / or a halide salt. (6) A plating solution according to any of (1) to (5) above, further containing an organic salt and / or an inorganic salt. (7) Any of the plating solutions (2) to (6) 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. (8) A plating solution containing any of the above (1) to (7), further comprising a pH buffer. (9) Any of the plating solutions (1) to (8) 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. (10) 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 (9) 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 uniformly electrodeposited without large variations in film thickness or other characteristics. [[BRIEF DESCRIPTION OF THE DRAWINGS]]

[0012] [Figure 1] It is a photographic diagram showing the Hull cell test result in Example 1 according to the present invention. [Figure 2] It is a photographic diagram showing the Hull cell test result in Example 2 according to the present invention. [Figure 3] It is a photographic diagram showing the Hull cell test result in Comparative Example 1 using a plating solution different from that of the present invention. [Figure 4] It is a photographic diagram showing the Hull cell test result in Comparative Example 2 using a plating solution different from that of the present invention. [[MODE 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 Ni-Cr-(Mo / W)-based alloy film-forming plating solution that contains a metal ion source including ion sources of nickel, chromium, and molybdenum and / or tungsten, and one or more chemical species selected from the group consisting of ammonia, an amine, and an ammonium ion.

[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 nickel salts, chromium salts, various chromate salts, molybdenum salts, various molybdate salts, tungsten salts, and various tungstate salts, and these can also be used in this embodiment. It is also possible to use multiple ion sources of the same metal, such as chromium salts and chromate salts, 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, from the viewpoint of further improving the uniform electrodeposition of the plating solution, it is preferable to use a metal salt or metal 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., as well as sodium salts, potassium salts, and ammonium salts of molybdic acid and tungstic acid, etc., are preferred. Nickel sulfate, chromium sulfate, basic chromium sulfate, ammonium molybdate, and ammonium tungstate are particularly suitable as metal ion sources in this embodiment. A plating solution containing these metal ion sources allows for more uniform electrodeposition of a Ni-Cr-(Mo / W) alloy film with high corrosion resistance.

[0018] The system may also contain other metal ion sources, such as iron (Fe), cobalt (Co), manganese (Mn), copper (Cu), titanium (Ti), niobium (Nb), and aluminum (Al). By using these other metal ion sources in combination, for example, a Ni-Cr-Mo-Fe system containing small amounts of Mn and Co can be produced. (Registered trademark) X, and also Inconel, Incoloy, Waspaloy, DSALOYIt is also possible to form nickel-based alloy films with compositions such as (registered trademark). If desired, phosphates, silicates, etc., may be used in combination to create a plating solution for nickel-based alloy films containing phosphorus (P) and silicon (Si). The plating solution of this embodiment may make it possible to form alloy films with compositions that cannot be produced by metallurgical methods.

[0019] (Concentration of metal ion source) In the plating solution of this embodiment, the concentration of the metal ion source 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.

[0020] 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.

[0021] Furthermore, the total amount of the metal ion source, which is related to the concentration of each of the above metal components, will also be explained here. In this embodiment, "total amount of metal ion source" means 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 means the total molar amount of nickel, chromium, and molybdenum and / or tungsten; when forming a Ni-Cr-(Mo / W)-Fe alloy film, it means the total molar amount of nickel, chromium, molybdenum and / or tungsten, and iron. The amount of metals that do not constitute the plating film, such as alkali metals in molybdate salts, is not included. Generally, it means the total molar amount of Group 3 to Group 15, for example, Group 4 to Group 14 metals in the plating solution.

[0022] <Chemical species such as ammonia> The plating solution of this embodiment contains, along with a metal ion source, one or more chemical species selected from the group consisting of ammonia, amines, and ammonium ions. A plating solution containing such chemical species exhibits excellent uniform electrodeposition properties, making it possible to form nickel-based alloy films with a more uniform film thickness. This effect is achieved regardless of which component of the plating solution the above-mentioned chemical species originates from, for example, whether it comes from a pH adjuster or a conductive salt.

[0023] In this embodiment, the above chemical species may be derived from one or more sources selected from the group consisting of, for example, aqueous ammonia, alkylamines, and ammonium salts. There are no particular restrictions on the type of source. The plating solution of this embodiment can be obtained by blending a metal ion source or additive containing, for example, ammonia, amines, and / or ammonium ions. For example, ammonium chromate or ammonium molybdate may be used as the metal ion source, or pH adjusters or conductive salts containing ammonia, amines, or ammonium salts may be added. Alternatively, the solution can be prepared by using a metal ion source, pH adjuster, and conductive salt that do not contain ammonia, amines, and ammonium ions, and separately blending other components containing ammonia, amines, and / or ammonium ions.

[0024] (Ammonia water) When the plating solution of this embodiment contains ammonia, it is preferable to use aqueous ammonia as the supply source. Aqueous ammonia is easy to handle because it is a liquid at room temperature and is unlikely to reduce the manufacturing efficiency of the plating solution. Furthermore, since various commercially available products are on the market, it is also suitable from the viewpoint of cost reduction. There are no particular restrictions on the aqueous ammonia that can be used; for example, a general-purpose product with an ammonia concentration of 20 to 40% by mass, particularly 25 to 35% by mass, can be used.

[0025] (amine) There are no particular restrictions on the amines used in this embodiment. Examples include alkylamines such as monomethylamine, monoethylamine, monopropylamine, monobutylamine, monohexylamine, monooctylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, methyldiethylamine, ethyldimethylamine, and piperidine; aromatic amines such as pyridine, methylpyridine, ethylpyridine, dimethylpyridine, imidazole, and bipyridine; hydroxyl group-containing amines such as monomethanolamine, monoethanolamine, trimethanolamine, and triethanolamine; and DBU, but are not limited to these.

[0026] From the standpoint of ease of handling and cost, it is preferable to use alkylamines, particularly trialkylamines, such as trimethylamine and triethylamine. Multiple types of amines can also be used in combination. Furthermore, it is possible to use a mixture containing ammonia or ammonium ions as the source of the amine.

[0027] (Ammonium ions) There are no particular restrictions on the type of ammonium ion. For example, NH4 +Examples of ammonium ions include, but are not limited to, ammonium ions in the narrow sense represented by the chemical formula; alkylammonium ions such as tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, and piperidinium ion; and aromatic ammonium ions such as pyridinium ion and imidazolium ion.

[0028] These ammonium ions can be obtained by dissolving ammonium salts or bases in a plating solution, for example, with halogen ions such as hydroxy anions and chlorine, inorganic ions such as sulfate ions, nitrate ions, and phosphate ions, or organic ions such as acetate anions as counteranions. Preferably, ammonium compounds in the narrow sense, such as ammonium hydroxide (NH4OH), ammonium sulfate, ammonium phosphate, and ammonium acetate; tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and their sulfates and halide salts, especially ammonium hydroxide and / or ammonium sulfate are used. These ammonium compounds are highly water-soluble and low-cost, making them suitable as raw materials for plating solutions.

[0029] Ammonium ions can also be formed by adding ammonia or amines to the plating solution. In this embodiment, there are no particular restrictions on the pH of the plating solution, but in order to further improve uniform electrodeposition, it is preferable to set the pH of the plating solution to about 0.5 to 12, for example, about 0.5 to 10, more preferably about 0.5 to 7.5, even more preferably about 1.0 to 6.0, and especially about 2.0 to 4.0. When ammonia or amines are added to such an acidic plating solution as a pH adjuster, at least a portion of them will naturally become ammonium ions. In this embodiment, it is preferable that the plating solution contains both ammonia and / or amines and ammonium ions as the above chemical species, and more preferably ammonia and ammonium ions in the narrow sense.

[0030] In the plating solution of this embodiment, the concentration of the above chemical species is preferably 0.01 mol / L or higher, more preferably 0.05 mol / L or higher, and even more preferably 0.1 mol / L or higher. For example, it is preferable to have a concentration of 0.01 to 10.0 mol / L, more preferably 0.05 to 5.0 mol / L, and especially preferably around 0.1 to 3.0 mol / L. With such a concentration, it becomes easier to form a nickel-based alloy film with a more uniform composition and film thickness.

[0031] While this invention is not limited by any particular theory, it is possible that these chemical species play a role in suppressing fluctuations in ion concentration and pH in the plating solution. The presence of these chemical species may suppress changes in the solution state during the plating process, resulting in improved electrodeposition properties.

[0032] <Solvent> In the plating solution of this embodiment, the solvent containing the metal ion source and the above chemical species is preferably water, but it may also contain organic solvents such as alcohols like methanol and ethanol; ethers such as tetrahydrofuran (THF), dioxane, and various glimes; carbonate esters 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 type of metal salt and chemical species used, an organic solvent may also be used as the main solvent.

[0033] <Additives> The plating solution of this embodiment may contain, along with the metal ion source and the above-mentioned chemical species, various additives such as complexing agents, 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. As mentioned above, ammonia, amines, and / or ammonium ions may be added as conductive salts or pH adjusters. For example, in a plating solution containing ammonium sulfate as a conductive salt or aqueous ammonia as a pH adjuster, these additives are already present, but other types of conductive salts and pH adjusters may be added in addition.

[0034] Among the additives mentioned above, the uniform electrodeposition properties of the plating solution can be further improved by incorporating complexing agents, conductive salts, pH adjusters, and pH buffers. Complexing agents, in particular, are additives that can contribute to improving electrodeposition properties. Some of these additives will be explained below.

[0035] <Complexing agent> The plating solution of this embodiment preferably contains a complexing agent along with the metal ion source and the above-mentioned chemical species. In this embodiment, the complexing agent may be of any type, and conventional ones can be used. Although the above-mentioned ammonia and amine can form complexes with transition metals such as nickel and chromium under certain conditions, they cannot form complexes under various conditions, including acidic conditions, for example. Therefore, in this embodiment, the above-mentioned chemical species are treated as not falling under the category of complexing agents.

[0036] 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.

[0037] 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. If the plating solution contains an appropriate amount of such complexing agents, it is possible to further improve the uniformity of electrodeposition. 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.

[0038] (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.

[0039] (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.

[0040] (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.

[0041] (alcohol) Suitable alcohols as complexing agents include, for example, ethylene glycol, propylene glycol, diethylene glycol, and other glycols.

[0042] (Amount of complexing agent) In the plating solution of this embodiment, it is preferable that the amount of complexing agent relative to the total amount of metal ion source is between 0.01 equivalents and 4 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 4 equivalents, the uniform electrodeposition properties of the plating solution can be further improved, and a nickel-based alloy film with more uniform thickness can be formed.

[0043] In general, alloy plating uses multiple metals with different deposition potentials, so to form a desired type of alloy film with a uniform composition, complexing agents are often used in amounts exceeding the amount of metal ion source. In this study, when forming a plating film from a plating solution containing the above chemical species, an unexpected effect was observed: the electrodeposition properties of the plating solution were further improved by using a relatively small amount of complexing agent (0.01 to 4 equivalents) relative to the total amount of metal ion source.

[0044] 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. Furthermore, "total amount of metal ion source" is the sum of the molar amounts of all ion sources for the metal constituting the target plating film, as described above, and is a quantity 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.

[0045] In the plating solution of this embodiment, as described above, it is preferable that 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, be 0.01 equivalents or more and 4 equivalents or less. More 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 3.0 equivalents or less, more preferably 2.0 equivalents or less, particularly preferably 1.0 equivalent 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.

[0046] 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 4, depending on the type of plating film to be produced and the type of complexing agent, uniform electrodeposition can be further improved. 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.

[0047] (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, and especially these inorganic salts, 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. Furthermore, if the conductive salt is an ammonium salt, it also serves as a source of the above-mentioned chemical species.

[0048] 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. Among these, sodium sulfate, potassium sulfate, and ammonium sulfate are preferred, with ammonium sulfate being particularly preferred.

[0049] 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.

[0050] (pH adjuster) The plating solution of this embodiment may contain a pH adjusting agent to further improve uniform electrodeposition, and its pH may be adjusted to a range suitable for nickel alloy plating, for example, about 0.5 to 12, more preferably about 0.5 to 10, more preferably about 0.5 to 7.5, even more preferably about 1.0 to 6.0, and especially preferably about 2.0 to 4.0.

[0051] pH adjusters are particularly useful when using complexing agents. 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.

[0052] 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. Here, using a pH adjusting agent containing sulfuric acid as the acid, or using a pH adjusting agent containing alkali metal hydroxides, ammonia, and / or amines as the base, is preferable because it improves the conductivity of the plating solution. If the pH adjusting agent contains ammonia, amines, and / or ammonium ions, the pH adjusting agent also serves as a source of the above-mentioned chemical species.

[0053] (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 types. Examples include, but are not limited to, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and their salts. If the pH buffer contains ammonia, amines, and / or ammonium ions, the pH buffer also serves as a source of the above-mentioned chemical species.

[0054] (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.

[0055] 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.

[0056] (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.

[0057] (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.

[0058] (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.

[0059] 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. As mentioned earlier, some pH adjusters and conductive salts can also serve as sources of the above-mentioned chemical species, but in addition, one or two types of inorganic acids such as sulfuric acid and phosphoric acid, organic acids such as carboxylic acids and sulfonic acids, bases, or their salts may be used to exhibit various functions such as imparting conductivity, pH adjustment, buffering, and hydrogen generation suppression. The present invention also includes plating solutions for forming Ni-Cr-(Mo / W) alloy films that contain inorganic and / or organic acid salts.

[0060] <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 particular, if the plating solution contains a complexing agent, pH adjustment or "aging" treatment may be performed before use.

[0061] ≪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 and uniform film thickness can be formed.

[0062] 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.

[0063] 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.

[0064] <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, making it easier to form 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."

[0065] (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.

[0066] 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.

[0067] (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 bath during the process. However, in order to ensure a stable plating process and 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 a more homogeneous alloy film.

[0068] <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.

[0069] (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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] (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. 2 It 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 2It 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.

[0074] 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. However, a suitable pH range is generally around 0.5 to 12, or 0.5 to 10, particularly 0.5 to 7.5, and even 1.0 to 6.0, especially 2.0 to 4.0. 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, circulate with a pump, or stir with a paddle during the plating process.

[0075] (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.

[0076] ≪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 terms of film thickness and other properties 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.

[0077] 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]

[0078] 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.

[0079] ≪Example 1≫ Sulfuric acid and ammonia water were added to a chemical solution (aqueous solution) with the following composition to adjust the pH to 2.5, creating a plating solution (concentration of ammonia and / or ammonium ions: 0.25 mol / L). A degreased and acid-activated copper plate (Hull cell copper plate measuring 67 mm x 100 mm) was immersed in this plating solution as the cathode, and a Hull cell test was performed with IrO2 / Ti as the anode. The test was conducted at a solution temperature of 50°C and a current of 3 A for 5 minutes. Figure 1 shows a photograph of the appearance after the test, Table 1 below shows the width (wrap-around: maximum 100 mm) of the area where the plating film was formed (spanning from the low current density side to the high current density side) and the average thickness of the plating film at each current density based on the Hull cell test, and Table 2 below shows the content of each metal element.

[0080] [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

[0081] Examples 2-3 The same procedure as in Example 1 was followed, except that the amount of complexing agent relative to the total amount of metal ion source was 3.0 equivalents (Example 2) or 4.0 equivalents (Example 3). A photograph of the appearance after testing in Example 2 is shown in Figure 2. The penetration and average film thickness of the plating film at each current density for Examples 2 and 3 are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0082] ≪Comparative Example 1≫ The procedure was the same as in Example 2, except that an aqueous sodium hydroxide solution was used instead of aqueous ammonia. Figure 3 shows a photograph of the appearance after the test, Table 1 below shows the thickness of the plating film and the average film thickness at each current density, and Table 2 below shows the content of each metal element.

[0083] Example 4 The same procedure as in Example 1 was followed, except that a chemical solution (aqueous solution) with the following composition was used. The penetration and film thickness measurement results are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0084] [Composition of the chemical solution in Example 4] 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 • NaCl 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

[0085] ≪Comparative Example 2≫ The procedure was almost the same as in Comparative Example 1, except that a chemical solution (aqueous solution) with the following composition was used and a Ni anode was employed. The pH of the plating solution was adjusted to 2.8 by adding sulfuric acid and sodium hydroxide aqueous solution. Figure 4 shows the appearance after the test, Table 1 below shows the results of the thickness measurement and the thickness measurement, and Table 2 below shows the content of each metal element.

[0086] [Composition of the chemical solution in Comparative Example 2] 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 • NaCl 1.0 mol / L Amount of complexing agent relative to the total amount of metal ion source: 4.0 equivalents

[0087] Example 5 The same procedure as in Example 1 was followed, except that a chemical solution (aqueous solution) with the following composition was used, and the pH was adjusted to 2.5 using an aqueous sodium hydroxide solution along with sulfuric acid. That is, the plating solution in this example contains ammonium ions derived from conductive salts, not from pH adjusting agents. The results of the plate coverage and film thickness measurements are shown in Table 1, and the content of each metal element is shown in Table 2.

[0088] [Composition of the chemical solution in Example 5] 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 (NH3)2SO4 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

[0089] [Table 1]

[0090] [Table 2]

[0091] In Examples 1 to 5, which used a plating solution containing ammonia or ammonium ions according to the present invention, good uniform electrodeposition was observed, with a coverage of 80 mm or more. Furthermore, a plated film with almost no scorching or discoloration was obtained. Generally, suppressing scorching and discoloration is considered more important than ensuring film thickness. In Comparative Example 1, which did not contain ammonia or ammonium ions, the coverage was good at 88 mm, but scorching and discoloration were noticeable at high current densities. In Comparative Example 2, the coverage was remarkably poor at 39 mm, and scorching and discoloration were observed at low current densities. Moreover, even at high current densities, the amount of Mo deposition was small, and the resulting plated film could hardly be called a Ni-Cr-Mo alloy film.

[0092] In the present embodiment, the difference in film thickness due to differences in current density was also small. Considering that the film thickness differed significantly for each current density in Comparative Example 2, it is suggested that the plating solution of the present invention can reduce variations in film thickness due to plating conditions. This trend was particularly pronounced in Examples 1, 4, and 5, where the complexing agent equivalent was 1 or less. In Examples 1, 4, and 5, a coating thickness of nearly 100 mm was also measured, indicating that particularly excellent uniform electrodeposition can be achieved when the complexing agent equivalent is 2 or less, for example, 1 or less.

[0093] 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 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 metal ion source containing nickel, chromium, and molybdenum and / or tungsten ion sources, and one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ions, 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 complexing agent in an amount of 0.01 equivalents or more and 4 equivalents or less relative to the total amount of the metal ion source.

3. The plating solution according to claim 1 or 2, wherein the chemical species is derived from one or more sources selected from the group consisting of ammonia water, alkylamines, and ammonium salts.

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

5. The plating solution according to claim 4, wherein the conductive salt is a sulfate and / or a halide salt.

6. The plating solution according to claim 1 or 2, further comprising an organic salt and / or an inorganic salt.

7. The plating solution according to claim 2, 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.

8. The plating solution according to claim 1 or 2, further comprising a pH buffering agent.

9. A method for forming a Ni-Cr-(Mo / W) alloy film, comprising the step of plating using the plating solution described in claim 1 or 2.

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