Nickel-based alloy plating solution

Abstract

The present invention addresses the problem of providing a plating solution which has excellent throwing power and which can form an Ni-Cr-(Mo / W)-based alloy film having a more uniform thickness. The present invention also addresses the problem of providing a plating method. Provided is a plating solution for forming an Ni-Cr-(Mo / W)-based alloy film, said plating solution 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 an Ni-Cr-(Mo / W)-based alloy film, said method comprising a step for carrying out plating with the plating solution. The plating solution preferably further contains a complexing agent in an amount of 0.01-4 equivalents with respect to the total amount of the metal ion sources.

Description

Nickel alloy plating solution

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

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

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

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

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

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

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

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

[0009] The present inventors have discovered that when forming a coating of nickel-chromium-molybdenum and / or tungsten-based alloy (Ni—Cr—(Mo / W)-based alloy), adding one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ion to a plating solution enables a nickel-based alloy coating to be uniformly electrodeposited, and have completed the present invention.

[0010] That is, the present invention provides the following (1) to (10): (1) A plating solution for forming a Ni—Cr—(Mo / W)-based alloy film, containing a metal ion source including an ion source of nickel, chromium, and molybdenum and / or tungsten, and one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ion. (2) The plating solution of (1) above, further containing a complexing agent in an amount of 0.01 equivalents to 4 equivalents based on the total amount of the metal ion source. (3) The plating solution of (1) or (2) above, wherein the chemical species is derived from one or more sources selected from the group consisting of aqueous ammonia, alkylamine, and ammonium salt. (4) The plating solution of any of (1) to (3) above, further containing a conductive salt. (5) The plating solution of (4) above, wherein the conductive salt is a sulfate and / or a halide salt. (6) The plating solution of any of (1) to (5) above, further containing an organic acid salt and / or an inorganic acid salt. (7) The plating solution of any of (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) The plating solution of any of (1) to (7) above, further comprising a pH buffer. (9) The plating solution of any of (1) to (8) above, wherein the nickel concentration is 0.001 to 0.5 mol / L in elemental terms, the chromium concentration is 0.01 to 1.5 mol / L in elemental terms, and the total concentration of the molybdenum and the tungsten is within the ranges of 0.001 to 2.0 mol / L in elemental terms. (10) A method for forming a Ni—Cr—(Mo / W)-based alloy film, comprising the step of plating using the plating solution of any of (1) to (9) above.

[0011] The plating solution of the present invention has excellent throwing power, and the plating solution and method of the present invention enable uniform electrodeposition of a Ni—Cr—(Mo / W) alloy coating without significant variations in thickness, etc.

[0012] Fig. 1 is a photograph showing the results of a hull cell test in Example 1 according to the present invention. Fig. 2 is a photograph showing the results of a hull cell test in Example 2 according to the present invention. Fig. 3 is a photograph showing the results of a hull cell test in Comparative Example 1, which used a plating solution different from that of the present invention. Fig. 4 is a photograph showing the results of a hull cell test in Comparative Example 2, which used a plating solution different from that of the present invention.

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

[0014] 1. Plating Solution The plating solution according to this embodiment is a plating solution for forming a Ni—Cr—(Mo / W)-based alloy film, which contains a metal ion source including an ion source 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, for example, nickel salts, chromium salts, various chromates, molybdenum salts, various molybdates, tungsten salts, and various tungstates, and these can also be used in this embodiment. It is also possible to use multiple ion sources of the same metal, such as a chromium salt and a chromate, in combination. Salts such as nickel molybdate can also be used. In addition to these, salts of complex ions, such as ammonium complexes and cyano complexes of various metal ions, may also be used. However, from the viewpoint of further improving the throwing power of the plating solution, it is preferable to use metal salts or metal acid salts that are not complexes as the metal ion source.

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

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

[0019] (Concentration of Metal Ion Source) In the plating solution of this embodiment, the concentration of the metal ion source can be set arbitrarily depending on the type of the target plating film, the plating treatment conditions, etc. For example, the nickel concentration may be set to 0.001 to 0.5 mol / L in elemental terms, the chromium concentration may be set to 0.01 to 1.5 mol / L in elemental terms, and the total concentration of molybdenum and tungsten may be set to 0.001 to 2.0 mol / L in elemental terms.

[0020] Alternatively, the concentrations of these metal components may be set, in elemental terms, such that the nickel concentration is 0.001 to 0.5 mol / L, particularly 0.01 to 0.1 mol / L, the chromium concentration is 0.01 to 1.5 mol / L, particularly 0.1 to 1.0 mol / L, and the molybdenum concentration is 0.001 to 2.0 mol / L, particularly 0.01 to 1.0 mol / L, and if desired, tungsten may be used in place of or in addition to molybdenum to a concentration of about 0.001 to 2.0 mol / L, particularly 0.01 to 1.0 mol / L.

[0021] The total amount of metal ion sources, which is related to the concentration of each metal component, will also be described here. In this embodiment, the "total amount of metal ion sources" refers to the sum of the molar amounts of all ion sources for the metals that constitute the target plating film. For example, when forming a Ni—Cr—(Mo / W) alloy film, it refers to the total molar amount of nickel, chromium, and molybdenum and / or tungsten; and 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. This does not include the amount of metals that do not constitute the plating film, such as alkali metals in molybdates. Generally, it refers to the total molar amount of metals from Groups 3 to 15, e.g., Groups 4 to 14, in the plating solution.

[0022] <Chemical species such as ammonia> The plating solution of this embodiment contains, in addition to a metal ion source, one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ion. A plating solution containing such chemical species has excellent throwing power and can form a nickel-based alloy coating with a more uniform thickness. Note that this effect is achieved regardless of which component in the plating solution the chemical species originate from, for example, a pH adjuster or a conductive salt.

[0023] In this embodiment, the chemical species may be derived from one or more sources selected from the group consisting of, for example, aqueous ammonia, alkylamines, and ammonium salts. The type of source is not particularly limited. 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 a pH adjuster or conductive salt containing ammonia, amines, or ammonium salts may be added. Alternatively, the plating solution can be prepared by using a metal ion source, pH adjuster, and conductive salt that do not contain ammonia, amines, or ammonium ions, and then 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 ammonia water as a supply source. Ammonia water is easy to handle because it is a liquid at room temperature, and there is little risk of it reducing the production efficiency of the plating solution. In addition, various commercially available ammonia water products are available, making it suitable from the perspective of cost reduction. There are no particular limitations on the ammonia water that can be used; for example, a general-purpose product with an ammonia concentration of about 20 to 40 mass%, particularly about 25 to 35 mass%, can be used.

[0025] (Amine) The amine used in this embodiment is not particularly limited. 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 viewpoint 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, a mixture containing ammonia or ammonium ions can also be used as an amine source.

[0027] (Ammonium ion) There is no particular limitation on the type of ammonium ion. For example, NH ４ ＋ In addition 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, but are not limited to these.

[0028] These ammonium ions can be obtained by dissolving, for example, an ammonium salt or base having a counter anion such as a hydroxy anion, a halogen ion such as chlorine, an inorganic ion such as sulfate, nitrate or phosphate, or an organic ion such as acetate in the plating solution. Preferably, ammonium hydroxide (NH ４ammonium hydroxide, tetrabutylammonium hydroxide, and their sulfates and halide salts, particularly ammonium hydroxide and / or ammonium sulfate. These ammonium compounds are highly water-soluble and inexpensive, 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, the pH of the plating solution is not particularly limited. However, to further improve throwing power, the pH of the plating solution is preferably about 0.5 to 12, for example, about 0.5 to 10, particularly about 0.5 to 7.5, further about 1.0 to 6.0, and particularly about 2.0 to 4.0. When ammonia or an amine is added as a pH adjuster to a plating solution under such acidic conditions, at least a portion of the added ammonium ions naturally form. In this embodiment, the plating solution preferably contains both ammonia and / or an amine and ammonium ions as the above-mentioned chemical species, particularly ammonia and ammonium ions in the narrow sense.

[0030] In the plating solution of this embodiment, the concentration of the chemical species is preferably 0.01 mol / L or more, more preferably 0.05 mol / L or more, and even more preferably 0.1 mol / L or more. For example, it is preferably about 0.01 to 10.0 mol / L, more preferably 0.05 to 5.0 mol / L, and particularly preferably about 0.1 to 3.0 mol / L. Such a concentration makes it easier to form a nickel-based alloy film with a more uniform composition and film thickness.

[0031] Although the present invention is not limited to a specific theory, it is possible that these chemical species act to suppress fluctuations in ion concentration and pH in the plating solution. The presence of these chemical species may suppress changes in the solution state during plating work, thereby improving electrodeposition.

[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 may also contain organic solvents such as alcohols such as methanol and ethanol; ethers such as tetrahydrofuran (THF), dioxane, and various glymes; carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; nitrogen-containing solvents such as acetonitrile, dimethylformamide (DMF), and pyrrolidone; and sulfur-containing solvents such as dimethyl sulfoxide (DMSO). Depending on the purpose and the types of metal salts and chemical species used, an organic solvent can also be used as the main solvent.

[0033] <Additives> In addition to the metal ion source and the above-described chemical species, the plating solution of this embodiment may contain various additives, such as complexing agents, conductivity-imparting agents including conductive salts, pH adjusters, pH buffers, hydrogen generation inhibitors, dispersants, dispersion aids, emulsifiers, surfactants, brighteners, antioxidants, viscosity adjusters, wetting agents, and dyes. As described above, ammonia, amines, and / or ammonium ions may be added as conductive salts, pH adjusters, or the like. For example, a plating solution containing ammonium sulfate as a conductive salt or aqueous ammonia as a pH adjuster already contains these additives, but other types of conductive salts and pH adjusters may also be added.

[0034] Among the additives mentioned above, the throwing power of the plating solution can be further improved by adding a complexing agent, a conductive salt, a pH adjuster, and a pH buffer. In particular, the complexing agent is an additive that can contribute to improving throwing power. Some of these additives will be described below.

[0035] <Complexing Agent> The plating solution of this embodiment preferably contains a complexing agent in addition to the metal ion source and the above-mentioned chemical species. In this embodiment, any type of complexing agent may be used, and a conventional one may be used. Note that although the above-mentioned ammonia and amines can form complexes with transition metals such as nickel and chromium under certain conditions, they do not necessarily form complexes under various conditions, including acidic conditions. Therefore, in this embodiment, the above-mentioned chemical species are not considered to fall within the category of complexing agents.

[0036] Specific examples of the complexing agent include cyanides; various carboxylic acids and their salts; various amino acids and their salts; phosphorus-containing compounds such as pyrophosphates, nitrilotrimethylphosphonic acid and their salts, and tris(3-hydroxypropyl)phosphine; sulfur-containing compounds such as thiourea, thioglycolic acid, thiodiglycolic acid, thioglycol, thiodiglycol, mercaptosuccinic acid, 3,6-dithia-1,8-octanediol, 3,6,9-trithiadecane-1,11-disulfonic acid, thiobis(dodecaethylene glycol), di(6-methylbenzothiazolyl)disulfide trisulfonic acid, di(6-chlorobenzothiazolyl)disulfide disulfonic acid, dithiodianiline, dipyridyl disulfide, mercaptosuccinic acid, sulfites, and thiosulfates; and alcohols; and further, ethylenediamine, ascorbic acid, gluconolactone, and glucoheptonolactone, but are not limited to these. It is also possible to use a plurality of types of complexing agents in combination.

[0037] The complexing agent is preferably one or more selected from the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylates, amino acids, amino acid salts, and alcohols. Plating solutions containing an appropriate amount of such complexing agents can further improve throwing power. Among these, carboxylic acids, hydroxycarboxylic acids, and salts thereof, and hydroxycarboxylic acids in particular, are preferred. These complexing agents are described in more detail below, but the complexing agents that can be used as components of the plating solution of this embodiment are not limited to those listed below.

[0038] (Carboxylic Acid and Its Salt) Carboxylic acids suitable as complexing agents include aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, and hexanoic acid; aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, maleic acid, and malic acid; aliphatic tricarboxylic acids such as aconitic acid; and aromatic carboxylic acids such as benzoic acid, salicylic acid, phthalic acid, and cinnamic acid. Carboxylic acid salts include their sodium salts, potassium salts, and ammonium salts. The salt of a carboxylic acid having multiple carboxy groups may be a salt formed by only some of the carboxy groups, or a double salt, such as sodium hydrogen oxalate or potassium sodium oxalate.

[0039] (Hydroxycarboxylic acid and its salt) Examples of hydroxycarboxylic acid suitable as a complexing agent include glycolic acid, gluconic acid, citric acid, glucoheptonic acid, tartaric acid, diglycolic acid, etc. Examples of hydroxycarboxylic acid salts include sodium salts, potassium salts, ammonium salts, etc. For example, sodium hydrogen tartrate and potassium sodium tartrate may be used.

[0040] (Amino Acids and Their Salts) Examples of amino acids (aminocarboxylic acids) suitable as complexing agents include glycine, α-alanine, β-alanine, cystine, anthranilic acid, aspartic acid, glutamic acid, aminodiacetic acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraminehexaacetic acid (TTHA), ethylenedioxybis(ethylamine)-N,N,N',N'-tetraacetic acid, and aromatic amino acids such as pyridinedicarboxylic acid. Examples of amino acid salts include sodium salts, potassium salts, and ammonium salts thereof.

[0041] (Alcohol) Examples of alcohols suitable as complexing agents include glycols such as ethylene glycol, propylene glycol, and diethylene glycol.

[0042] (Amount of Complexing Agent) In the plating solution of this embodiment, the amount of complexing agent relative to the total amount of the metal ion source is preferably 0.01 equivalents or more and 4 equivalents or less. By setting the ratio of the amount of complexing agent relative to the amount of the metal ion source within the range of 0.01 to 4 equivalents, the throwing power of the plating solution can be further improved, and a nickel-based alloy film with a more uniform thickness can be formed.

[0043] Generally, in alloy plating, multiple metals with different deposition potentials are used, and therefore, in order to form a desired type of alloy film with a uniform composition, a complexing agent is often used in an amount equal to or greater than the amount of metal ion source. In this study, in forming a plating film from a plating solution containing the above chemical species, an unexpected effect was achieved in that the electrodeposition properties of the plating solution were further improved by using a relatively small amount of complexing agent, i.e., 0.01 to 4 equivalents, relative to the total amount of metal ion source.

[0044] Here, "equivalent" means the ratio of the molar amount of the complexing agent molecules to the total molar amount of the metal ions constituting the plating film. As mentioned above, the "total amount of metal ion sources" is the sum of the molar amounts of all ion sources for the metals constituting the target plating film, and is the amount based on the metal element. For example, when 0.1 mole of Cr is added to the plating solution, ２ (SO ４ ) ３ When the chromium ion source is contained, the amount of the chromium ion source is calculated as 0.2 mole.

[0045] In the plating solution of this embodiment, as described above, the amount of complexing agent relative to the total amount of metal ion sources, i.e., the molar ratio of complexing agent amount to total amount of metal ion sources, is preferably 0.01 equivalents or more and 4 equivalents or less. More preferably, the molar ratio of complexing agent amount to total amount of metal ion sources is, for example, 0.05 equivalents or more, even more preferably 0.10 equivalents or more, even more preferably 0.20 equivalents or more, even more preferably 0.30 equivalents or more, and particularly preferably 0.40 equivalents or more. The molar ratio is also preferably set to 3.0 equivalents or less, more preferably 2.0 equivalents or less, particularly preferably 1.0 equivalents or less, even more preferably 0.8 equivalents or less, or even 0.6 equivalents or less, for example, 0.10 to 2.0 equivalents, particularly 0.20 to 1.5 equivalents, further 0.30 to 1.0 equivalents, and particularly preferably 0.40 to 0.90 equivalents.

[0046] In this way, the throwing power can be further improved by appropriately selecting the molar ratio of the amount of complexing agent to the total amount of metal ion sources within the range of 0.01 to 4 depending on the type of target plating film, the type of complexing agent, etc. The concentration of the complexing agent in the plating solution is determined mainly based on the total concentration of the metal ion sources, and is preferably set to about 0.01 to 1 mol / L, particularly about 0.1 to 0.8 mol / L.

[0047] (Conductive Salt) The type of conductive salt is not particularly limited, and various inorganic salts such as halides, sulfates, nitrates, and phosphates, as well as organic salts such as tetraalkylammonium salts, pyridinium salts, and sulfonates, can be used. Among these, sulfates and / or ammonium salts, particularly these inorganic salts, are preferred. A plating solution containing sulfates or ammonium salts as the conductive salt promotes balanced deposition of the metals that form the desired coating, making it easier to form alloy plating with more uniform composition and film thickness. Furthermore, when the conductive salt is an ammonium salt, the conductive salt 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, ammonium phosphate, etc. Among these, sodium sulfate, potassium sulfate, and ammonium sulfate are preferred, with ammonium sulfate being particularly preferred.

[0049] There is no particular limitation on the concentration of these conductive salts in the plating solution, and they can be set to a desired value depending on the concentration of the metal components, etc. For example, the concentration may be about 0.1 to 3 mol / L, particularly about 0.25 to 2 mol / L, but is not limited to these ranges.

[0050] (pH Adjuster) The plating solution of the present embodiment may contain a pH adjuster to further improve the throwing power, and the pH may be adjusted to a range suitable for nickel-based alloy plating, for example, about 0.5 to 12, particularly about 0.5 to 10, more preferably about 0.5 to 7.5, even more preferably about 1.0 to 6.0, and particularly preferably about 2.0 to 4.0.

[0051] pH adjusters are particularly useful when a complexing agent is used. Each complexing agent has a pH at which complex formation is facilitated, so it is preferable to adjust the pH of the plating solution before use. Alternatively, the plating solution may be subjected to an operation known as "aging," in which the solution is maintained at a specific temperature and pH for a certain period of time. It is preferable to use a pH adjuster during such an operation.

[0052] The pH adjuster added to the plating solution of this embodiment is not particularly limited, and various acids and / or bases can be used depending on the pH during the intended plating process or aging. Here, using a pH adjuster containing sulfuric acid as the acid or a pH adjuster containing alkali metal hydroxide, ammonia, and / or amine as the base is preferred, as it provides the advantage of improving the conductivity of the plating solution. When the pH adjuster contains ammonia, amine, and / or ammonium ions, the pH adjuster also serves as a source of the above-mentioned chemical species.

[0053] (pH Buffer) The plating solution of this embodiment preferably further contains a pH buffer to stabilize the deposition reaction of the target metal. Although a pH buffer can be considered a type of pH adjuster in the broad sense, it is treated here as a component different from a pH adjuster in the narrow sense. There are no particular limitations on the type of pH buffer, and a buffer suitable for the target pH range can be selected and used from various known buffers. Examples include, but are not limited to, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and salts thereof. When the pH buffer contains ammonia, amines, and / or ammonium ions, the pH buffer also serves as a source of the above chemical species.

[0054] (Hydrogen Generation Inhibitor) The plating solution of this embodiment may also contain a hydrogen generation inhibitor. By including a hydrogen generation inhibitor in the plating solution, it becomes easier to suppress a decrease in current efficiency during plating. Furthermore, as a result of suppressing hydrogen gas generation at the cathode, it becomes easier to prevent scorching and hydrogen embrittlement of the plating film. Scorching (burning) is a defect in which the current density at the cathode becomes excessive, resulting in the formation of a rough and brittle plating film, and is a phenomenon caused by the precipitation of metal hydroxides due to an increase in pH at the cathode interface. There are no particular limitations on the hydrogen generation inhibitor, and various known ones can be used. For example, boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and salts thereof can be used, with boric acid, citric acid, and salts thereof being particularly preferred.

[0055] When a hydrogen generation inhibitor is contained, its concentration is preferably about 0.01 to 2.0 mol / L, particularly about 0.1 to 1.5 mol / L. Some of these hydrogen generation inhibitors can also function as the complexing agent or pH buffer described above. Therefore, by adjusting the concentration of, for example, citric acid in the plating solution to about 0.01 to 2.0 mol / L, further about 0.02 to 1.5 mol / L, particularly about 0.10 to 1.0 mol / L, it is possible to achieve all of the functions of complex formation, pH adjustment, and hydrogen generation inhibition.

[0056] (Brightener) The plating solution of this embodiment may contain a brightener. Brighteners not only impart brightness to the plating film, but may also promote metal deposition in recesses and flatten the plating surface. There are no particular limitations on the type of brightener, and various aldehydes, triazines, imidazole, indole, quinoline, 2-vinylpyridine, aniline, phenanthroline, neocuproine, picolinic acid, thioureas, benzothiazoles, sulfides, and the like can be used. When a brightener is contained, its concentration is preferably about 0.01 mg / L to 500 mg / L, and particularly preferably about 0.1 mg / L to 10 mg / L.

[0057] (Surfactant) The surfactant is not particularly limited, and a desired surfactant can be selected from ordinary anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. When a surfactant is contained, its concentration is preferably about 1 mg / L to 50 g / L, particularly about 5 mg / L to 10 g / L.

[0058] (Antioxidant) The antioxidant is used to prevent oxidation of the metal salt. Examples of the antioxidant include, but are not limited to, hypophosphorous acids, ascorbic acid, phenolsulfonic acid, cresolsulfonic acid, hydroquinonesulfonic acid, hydroquinone, α- or β-naphthol, catechol, resorcinol, phloroglucinol, hydrazine, phenolsulfonic acid, catecholsulfonic acid, hydroxybenzenesulfonic acid, naphtholsulfonic acid, and salts thereof. The antioxidant can be contained at a concentration of, for example, about 0.1 g / L to 500 g / L, particularly about 1 g / L to 100 g / L.

[0059] Although several representative additives have been described above, the plating solution of the present invention may contain various other additives. Furthermore, one or two additives may also serve as functional agents that provide multiple effects. As noted above, some pH adjusters and conductive salts can serve as sources of the above-mentioned chemical species. In addition, one or two inorganic acids, such as sulfuric acid and phosphoric acid, organic acids, such as carboxylic acids and sulfonic acids, bases, and their salts may also be used to provide various functions, such as conductivity, pH adjustment, buffering, and hydrogen generation inhibition. The present invention also encompasses plating solutions for forming Ni—Cr—(Mo / W)-based alloy films that contain inorganic acid salts and / or organic acid salts.

[0060] <Preparation of Plating Solution> The plating solution of this embodiment can be prepared from the components described above using a conventional method, and the details may be determined appropriately taking into consideration the composition and amount of each component, etc. In particular, when the plating solution contains a complexing agent, the pH may be adjusted or a "aging" treatment may be performed before use.

[0061] 2. Method for Forming Alloy Film By performing a plating process using the plating solution of the various embodiments described above, it is possible to form a desired Ni—Cr—(Mo / W) alloy film on various substrates. Therefore, the method for forming a Ni—Cr—(Mo / W) alloy film can be defined as a method including a step of performing a plating process using the plating solution described above. According to such a method, it is possible to form a nickel-based alloy film with excellent throwing power and a uniform film thickness.

[0062] There are no particular limitations on the method and conditions for plating, and general electrolytic plating may be carried out under conventional conditions depending on the type of nickel-based alloy film to be formed and the substrate to be plated.

[0063] Specifically, the temperature of the plating solution can be set to about 10 to 90°C, and the current density can be set to 0.01 to 50 A / dm ２ It can be about.

[0064] <Outline of Plating Treatment> A nickel-based alloy coating can be formed by, for example, immersing an object to be plated as a cathode together with an anode in the plating solution of the present invention and passing a current through it. Here, if the solution temperature is 10°C or higher and the current density is 0.01 A / dm ２ If the solution temperature is 90°C or less, changes in concentration due to evaporation or boiling of the plating solution are suppressed, making it easier to form a nickel-based alloy film with a more uniform composition and film thickness. ２ If the temperature is below this range, defects such as scorching in the resulting alloy film can be easily suppressed. Note that although the plating solution in the plating tank is sometimes called a "plating bath," in this embodiment, both are considered to be the same and are referred to as a "plating solution."

[0065] (Object to be plated) Here, the object to be plated in this embodiment may be any material as long as it is conductive, and may include, of course, various metal materials and conductive ceramic materials, as well as non-conductive ceramics, glass, carbon materials, resins, rubber, wood, and other non-conductors that have been made conductive by, for example, electroless plating or metal vapor deposition. When plating conductive materials such as metals, a material having another plating layer applied to the substrate may also be used. There are also no particular limitations on the shape of the object to be plated.

[0066] Considering the excellent heat resistance and corrosion resistance of Ni—Cr—(Mo / W) alloys, including Hastelloy, the alloy coating method of this embodiment can be particularly effective when the object to be plated is a heat-resistant or corrosion-resistant material. For example, by forming a Ni—Cr—(Mo / W) alloy coating on a substrate made of iron or stainless steel, or on such a substrate plated with chrome or nickel, a material with particularly excellent heat resistance and corrosion resistance can be obtained. Depending on the intended use temperature, a metal layer or the like may be formed in advance by electroless plating or the like on the surface of a heat-resistant resin material, such as a thermoset polyimide or its fiber composite, and then subjected to the plating process of this embodiment. Polymer materials treated by the plating method of this embodiment can be used as lightweight, corrosion-resistant materials.

[0067] (Anode) There is no particular limitation on the anode used in the plating process. For example, an electrode made of nickel or a nickel-based alloy may be used as the anode, and nickel, chromium, molybdenum, etc. may be supplied into the plating bath during the process. However, in order to proceed with the plating process stably and form a more uniform alloy film, it is preferable to use an electrode based on an insoluble material, such as iridium oxide, tantalum oxide, platinum, lead, lead alloy, boron-doped diamond, graphite, etc. as the anode. These anodes do not dissolve in the plating solution during the process, or dissolve only slightly, so there is no risk of changing the composition of the plating solution, and as a result, it is easier to form a more uniform alloy film.

[0068] <Practical Plating Treatment> The plating treatment for forming a nickel-based alloy film on various conductive or non-conductive substrates will be described in more detail below.

[0069] (Pretreatment) Prior to the plating treatment of this embodiment, the substrate to be plated may be subjected to pretreatment, such as degreasing or acid activation treatment. In particular, when plating non-conductors such as general ceramics or resins, it is desirable to perform pretreatment such as electroless plating, sputtering, or vapor deposition in advance to form a metal layer or graphite layer on the surface to impart conductivity.

[0070] The pretreatment method is not particularly limited, and a desired method can be used depending on the substrate to be used, etc. To explain a more specific embodiment using a case where a nonconductor is subjected to a general electroless plating treatment as an example, for example, the surface to be treated of the substrate is optionally degreased and cleaned, then subjected to an etching treatment, and then brought into contact with a catalyst-imparting enhancing liquid (conditioning). Next, a catalyst such as palladium is imparted to the surface by contact with a catalyst-imparting treatment liquid, and the catalyst is then optionally activated with an inorganic acid, a reducing agent, or the like, and electroless nickel plating, electroless copper plating, electroless cobalt plating, or the like is carried out.

[0071] The substrate after electroless plating may be further subjected to strike plating treatment such as copper strike plating, nickel strike plating, silver strike plating, or gold strike plating; or general-purpose plating treatment such as nickel plating, chrome plating, nickel chrome plating, tin plating, tin silver plating, copper plating, gold plating, or silver plating.

[0072] When the substrate is made of a conductive material such as a metal or conductive ceramic, the substrate may be subjected to the above-mentioned degreasing, etching, strike plating, general-purpose plating, etc., if desired.

[0073] (Plating Treatment Procedure) The optionally pretreated object (substrate) is subjected to plating treatment in the plating solution of the present invention. In the plating treatment, the solution temperature is set to 10 to 90°C and the current density is set to 0.01 to 50 A / dm as described above. ２ More preferably, the liquid temperature is 20 to 80°C, particularly 25 to 70°C, and the current density is 0.1 to 20 A / dm ２ , especially 1 to 10 A / dm ２The plating time may be appropriately set depending on the type of nickel-based alloy film to be formed, the solution temperature during the treatment, and the current density, but is preferably about 1 to 300 minutes, and particularly about 3 to 120 minutes.

[0074] The appropriate pH of the plating solution during plating varies depending on the type of nickel-based alloy film desired and the composition of the plating solution used, but may be, for example, about 0.5 to 12, or about 0.5 to 10, preferably about 0.5 to 7.5, further preferably about 1.0 to 6.0, and particularly preferably about 2.0 to 4.0. Plating under these conditions can easily form a Ni—Cr—(Mo / W)-based alloy film with excellent uniformity in composition and film thickness, such as a nickel-based alloy film with a Hastelloy-like composition. During plating, it is preferable to agitate the solution by aeration, pump circulation, paddle stirring, or the like.

[0075] (Post-treatment) Plated parts having a nickel-based alloy coating formed thereon as described above may, of course, be used as is, or an electrolytic chemical conversion coating and / or an immersion chemical conversion coating may be applied to the alloy coating. Ni—Cr—(Mo / W)-based alloy coatings generally have excellent heat resistance and corrosion resistance, but the corrosion resistance of plated parts can be further enhanced by applying a treatment film. There are no particular restrictions on the electrolytic chemical conversion coating and immersion chemical conversion coating, and conventional treatment methods can be applied as desired. Examples include, but are not limited to, chromate treatment, wax treatment, treatment with a solution of benzotriazole or triazine thiol, treatment with a solution of a compound having an amino group or an imino group, anodizing, and heat treatment.

[0076] 3. Plated Parts>> By using the plating method of the present embodiment as described above, it is possible to form a Ni—Cr—(Mo / W) alloy coating on various substrates, which has excellent uniformity in film thickness, etc. Hereinafter, embodiments relating to plated parts produced using the plating solution and plated parts produced by the plating method will be described.

[0077] The plated part of this embodiment exhibits excellent heat resistance and corrosion resistance due to the Ni—Cr—(Mo / W) alloy coating. Furthermore, any material can be used as the substrate. Therefore, for example, using a material with relatively good workability, such as iron or stainless steel, as the substrate, it is possible to produce plated parts with complex and fine shapes that are simultaneously excellent in heat resistance and corrosion resistance and are also low-cost. Lightweight, corrosion-resistant materials can also be produced by plating various shapes of polymeric materials, particularly heat-resistant polymeric materials based on polyimide or the like. The present invention provides a variety of plated parts with excellent heat resistance and corrosion resistance, such as industrial materials, automobile parts, building materials, home appliance parts, and electronic parts, in various shapes.

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way.

[0079] Example 1 A plating solution (aqueous solution) having the following composition was prepared by adding sulfuric acid and aqueous ammonia to adjust the pH to 2.5, and the concentration of ammonia and / or ammonium ions was 0.25 mol / L. A copper plate (a hull cell copper plate measuring 67 mm long x 100 mm wide) that had been degreased and then acid-activated was immersed as a cathode in the plating solution, and IrO ２ A Hull cell test was conducted using a 1000-kJ / Ti anode. The test was conducted for 5 minutes at a solution temperature of 50°C and a current value of 3 A. Figure 1 shows a photograph of the appearance after the test, and Table 1 below shows the width (maximum throwing ratio: 100 mm) of the region where the plating film was formed (ranging from the low current density side to the high current density side) and the average thickness of the plating film at each current density based on the Hull cell test. Table 2 below also shows the content of each metal element.

[0080] [Composition of chemical solution in Example 1] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ MoO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L Na ２ SO ４ 1.0 mol / L・H３ BO ３ 1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0081] Examples 2 and 3 The same procedure as in Example 1 was carried out, 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 the test in Example 2 is shown in Figure 2. The throwing power and average thickness of the plated film at each current density in 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 same procedure as in Example 2 was carried out, except that an aqueous sodium hydroxide solution was used instead of aqueous ammonia. A photograph of the appearance after the test is shown in Fig. 3, the throwing power and the average thickness of the plated film at each current density are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0083] Example 4 The same procedure as in Example 1 was carried out, except that a chemical solution (aqueous solution) having the following composition was used. The throwing power 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 chemical solution in Example 4] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ MoO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L NaCl 1.0 mol / L H ３ BO ３ 1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0085] Comparative Example 2: Substantially the same procedure as in Comparative Example 1 was carried out, except that a chemical solution (aqueous solution) with the following composition was used, and a Ni anode was used. The pH of the plating solution was adjusted to 2.8 by adding sulfuric acid and an aqueous solution of sodium hydroxide. A photograph of the appearance after the test is shown in Figure 4, the results of the throwing power and film thickness measurements are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0086] [Composition of Chemical Solution in Comparative Example 2] NiCl ２ 0.042mol / L ・CrCl ３ 0.19mol / L ・Na ２ MoO ４ ・2H ２ O 0.17 mol / L Sodium gluconate 0.16 mol / L Formic acid 0.78 mol / L Glycine 0.67 mol / L H ３ BO ３ 0.29 mol / L 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 carried out, except that a chemical solution (aqueous solution) having the following composition was used, and the pH was adjusted to 2.5 using an aqueous solution of sodium hydroxide together with sulfuric acid. That is, the plating solution of this example contains ammonium ions derived from the conductive salt, not from the pH adjuster. The results of the throwing power and film thickness measurements are shown in Table 1, and the content of each metal element is shown in Table 2.

[0088] [Composition of chemical solution in Example 5] NiSO ４ ・6H ２ O 0.02 mol / L Basic chromium sulfate 0.30 mol / L Na ２ MoO ４ ・2H ２ O 0.02 mol / L Gluconic acid 0.30 mol / L (NH ３ ) ２ SO ４ 1.0 mol / L・H ３ BO ３1.0 mol / L: Amount of complexing agent relative to the total amount of metal ion source: 0.88 equivalents

[0089]

[0090]

[0091] In Examples 1 to 5, which used a plating solution containing ammonia or ammonium ions according to the present invention, the throwing weight was 80 mm or more, demonstrating good throwing power. Furthermore, plating films with almost no scorching or discoloration were obtained. In general, 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 throwing weight was good at 88 mm, but scorching and discoloration were noticeable on the high current density side. In Comparative Example 2, the throwing weight was significantly poor at 39 mm, and scorching and discoloration were observed on the low current density side. Furthermore, the amount of Mo deposited was small even on the high current density side, making it difficult to call the resulting plating film a Ni-Cr-Mo alloy film.

[0092] In the present Examples, the difference in film thickness due to differences in current density was also small. Considering that the film thickness varied significantly depending on the current density in Comparative Example 2, it is suggested that the plating solution of the present invention can reduce film thickness variations due to plating conditions. This tendency was particularly noticeable in Examples 1, 4, and 5, in which the complexing agent equivalent was 1 or less. In Examples 1, 4, and 5, a throwing weight of nearly 100 mm was measured, indicating that particularly excellent throwing power can be achieved when the complexing agent equivalent was 2 or less, for example, 1 or less.

[0093] As described above, the present invention provides a plating solution and a plating method that have excellent throwing power and can form a Ni—Cr—(Mo / W)-based alloy coating with a more uniform thickness. According to the present invention, it is possible to form a plating film of a nickel-based alloy, such as Hastelloy, with a uniform composition and thickness on the surface of components of various shapes and materials, thereby producing plated parts that are lightweight and low-cost, yet have excellent heat resistance and corrosion resistance.

Claims

1. A plating solution for forming a Ni—Cr—(Mo / W) alloy film, comprising a metal ion source containing an ion source 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.

2. The plating solution according to claim 1, further comprising a complexing agent in an amount of 0.01 equivalent or more and 4 equivalents or less based on 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 aqueous ammonia, 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 containing an organic acid salt and / or an inorganic acid 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 containing a pH buffer.

9. The plating solution according to claim 1 or 2, wherein the concentration of nickel is in the range of 0.001 to 0.5 mol / L in terms of element, the concentration of chromium is in the range of 0.01 to 1.5 mol / L in terms of element, and the total concentration of molybdenum and tungsten is in the range of 0.001 to 2.0 mol / L in terms of element.

10. A method for forming a Ni—Cr—(Mo / W) alloy film, comprising a step of plating using the plating solution according to claim 1 or 2.

Images