Nickel alloy plating solution

Abstract

The present invention addresses the problem of providing a plating solution and a plating method which have excellent uniform electrodeposition properties and are capable of forming a Ni-Cr-(Mo / W) alloy coating film with a more uniform film thickness. A plating solution for forming a Ni-Cr-(Mo / W) alloy coating film, the plating solution containing: 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. And a method for forming a Ni-Cr-(Mo / W) alloy coating film, the method including a step for plating using the plating solution. It is preferable that the plating solution further contains a complexing agent in an amount of 0.01-4 equivalents (inclusive) relative to the total amount of the metal ion sources.

Description

Technical Field

[0001] This invention relates to a plating solution for forming coatings on nickel-based alloys. Background Technology

[0002] In the past, nickel-based alloys, represented by HASTELLOY (registered trademark), were often used as heat-resistant and corrosion-resistant materials. These nickel-based alloys have the following advantages: excellent heat and corrosion resistance, high durability against halogens, oxidizing or non-oxidizing chemicals, resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking.

[0003] Due to these advantages, nickel-based alloys can be used in high-temperature and corrosive environments. However, they also suffer from drawbacks such as hardness and difficulty in forming and processing. Therefore, materials using nickel-based alloys are difficult to process into complex shapes, and the high cost of the raw materials often leads to higher overall costs. Furthermore, nickel-based alloys have a relatively high specific gravity, making it difficult to achieve lightweight materials.

[0004] It was believed that if nickel-based alloys could be applied to various materials in the form of surface coatings, the difficulties in forming and processing could be solved, and cost reduction and weight reduction would become easier. Based on this idea, several attempts were made to form nickel-based alloy coatings through plating.

[0005] For example, Patent Document 1 discloses a plating method for an alloy, which uses a plating bath containing chromium ions, nickel and / or cobalt ions, and tungstic acid, molybdate and / or rhenium ions at specific concentrations. Patent Document 2 discloses a plating solution with a pH of 8-11 to improve the formation efficiency and appearance of the plating film. This solution uses gluconate as a complexing agent for nickel-based alloy plating and is mixed with nickel salts and molybdates.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 9-302496

[0009] Patent Document 2: Japanese Patent Application Publication No. 2005-082856 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] In existing methods as described above, it is not always possible to obtain 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 described later, uniform electrodeposition of the nickel-chromium-molybdenum alloy film is difficult. The same problem occurs in the plating solution described in Patent Document 2, which studies the types of complexing agents. Furthermore, in the nickel-molybdenum alloy plating solution described in Patent Document 2, since chromium ions are not present, it is difficult to exhibit sufficient acid resistance, etc. Even if chromium salts are simply added to this plating solution, it is not always possible to obtain a uniform plating film with a good appearance.

[0012] In order to solve the aforementioned problems, the present invention aims to provide a plating solution with excellent uniform electrodeposition properties, capable of forming nickel-chromium-molybdenum and / or tungsten alloy coatings with more uniform film thickness, and a method for forming a coating using the plating solution.

[0013] Methods for solving problems

[0014] The inventors have discovered that, in forming a coating of nickel-chromium-molybdenum and / or tungsten alloys (Ni-Cr-(Mo / W) alloys), by including one or more chemical species selected from the group consisting of ammonia, amine and ammonium ions in the plating solution, the nickel alloy coating can be uniformly electrodeposited, thus completing the present invention.

[0015] That is, the present invention provides the following (1) to (10).

[0016] (1) A plating solution for forming a Ni-Cr-(Mo / W) alloy coating, comprising: a metal ion source including nickel, chromium and molybdenum and / or tungsten ions; and one or more chemical species selected from the group consisting of ammonia, amine and ammonium ions.

[0017] (2) The plating solution as described in (1) above also contains a complexing agent in an amount of 0.01 equivalents to 4 equivalents relative to the total amount of the metal ion source.

[0018] (3) The plating solution as described in (1) or (2) above, wherein the chemical species is derived from one or more supply sources selected from the group consisting of ammonia, alkylamine and ammonium salt.

[0019] (4) The plating solution of any one of (1) to (3) above also contains conductive salt.

[0020] (5) The plating solution as described in (4) above, wherein the conductive salt is a sulfate and / or a halide salt.

[0021] (6) The plating solution of any one of (1) to (5) above also contains organic acid salts and / or inorganic acid salts.

[0022] (7) The plating solution as described in any one of (2) to (6) above, wherein the complexing agent is one or more selected from the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylate salts, amino acids, amino acid salts and alcohols.

[0023] (8) The plating solution of any one of (1) to (7) above also contains a pH buffer.

[0024] (9) The plating solution as described in any of (1) to (8) above, wherein the concentration of nickel is in the range of 0.001 to 0.5 mol / L, the concentration of chromium is in the range of 0.01 to 1.5 mol / L, and the total concentration of molybdenum and tungsten is in the range of 0.001 to 2.0 mol / L.

[0025] (10) A method for forming a Ni-Cr-(Mo / W) alloy coating, comprising a process of plating using the plating solution of any one of (1) to (9) above.

[0026] Invention Effects

[0027] The plating solution of the present invention exhibits excellent uniform electrodeposition properties. Furthermore, according to the plating solution and method of the present invention, Ni-Cr-(Mo / W) alloy films can be uniformly electrodeposited without significant deviations in film thickness or the like. Attached Figure Description

[0028] Figure 1 This is a photographic image showing the results of the Hull groove test in Embodiment 1 of the present invention.

[0029] Figure 2 This is a photographic image showing the results of the Hull groove test in Embodiment 2 of the present invention.

[0030] Figure 3 This is a photographic image showing the results of a Hull cell test in Comparative Example 1, which uses a plating solution different from that of the present invention.

[0031] Figure 4 This is a photographic image showing the Hull cell test results in Comparative Example 2, which uses a plating solution different from that of the present invention. Detailed Implementation

[0032] The present invention will now be described in detail based on the embodiments, but the present invention is not limited to these embodiments.

[0033] 1. Plating Solution

[0034] The plating solution of this embodiment is a plating solution for forming Ni-Cr-(Mo / W) alloy coatings, which contains: 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.

[0035] <Metal Ion Source>

[0036] The metal ion source contained in the plating solution contains at least nickel, chromium, and molybdenum and / or tungsten ion sources.

[0037] In this embodiment, ion sources such as nickel salts, chromium salts, various chromates, molybdenum salts, various molybdates, tungsten salts, and various tungstates are commonly used. Multiple ion sources of the same metal, such as chromium salts and chromates, can also be used in combination. Additionally, salts such as nickel molybdate can be used. Furthermore, salts of complex ions such as ammonium complexes and cyano complexes of various metal ions can also be used. However, from the viewpoint of further improving the uniform electrodeposition properties of the plating bath, it is preferable to use metal salts or metal acid salts that are not complexes as metal ion sources.

[0038] More preferred metal ion sources are nickel salts, chromium salts, molybdates, and tungstates. Among these, halides, sulfates, sulfites, nitrates, perchlorates, etc., of nickel and chromium, and sodium, potassium, and ammonium salts of molybdate and tungstate are preferred. In particular, nickel sulfate, chromium sulfate, basic chromium sulfate, ammonium molybdate, and ammonium tungstate are suitable as metal ion sources in this embodiment. Plating solutions containing these metal ion sources enable more uniform electrodeposition of Ni-Cr-(Mo / W) alloy films with high corrosion resistance.

[0039] As a metal ion source, other metals can also be included, such as iron (Fe), cobalt (Co), manganese (Mn), copper (Cu), titanium (Ti), niobium (Nb), and aluminum (Al). Such other types of metal ion sources can also be used to form nickel-based alloy coatings, such as HASTELLOY X containing small amounts of Mn and Co in a Ni-Cr-Mo-Fe system, and INCONEL, INCOLOY, WASPALOY, and DASLOY (registered trademarks). If necessary, a plating solution containing phosphorus (P) and silicon (Si) for nickel-based alloy coatings can also be prepared using phosphates, silicates, etc. According to this embodiment, the plating solution can also form alloy coatings with compositions that cannot be produced by metallurgical methods.

[0040] (Concentration of the metal ion source)

[0041] In the plating solution of this embodiment, the concentration of the metal ion source can be arbitrarily set according to the type of the target coating and the conditions of the plating process. For example, the concentration of nickel can be set to 0.001 to 0.5 mol / L, the concentration of chromium can be set to 0.01 to 1.5 mol / L, and the combined concentration of molybdenum and tungsten can be set to 0.001 to 2.0 mol / L.

[0042] Alternatively, the concentrations of these metal components can be set as follows: all in elemental form, such that the nickel concentration is 0.001–0.5 mol / L, particularly 0.01–0.1 mol / L; the chromium concentration is 0.01–1.5 mol / L, particularly 0.1–1.0 mol / L; the molybdenum concentration is 0.001–2.0 mol / L, particularly 0.01–1.0 mol / L; and the tungsten concentration is set to a level that, as desired, replaces or is added to molybdenum, is 0.001–2.0 mol / L, particularly 0.01–1.0 mol / L.

[0043] It should be noted that the total amount of metal ion sources related to the concentration of each of the aforementioned metal components is also explained here. In this embodiment, "total amount of metal ion sources" refers to the sum of the molar amounts of all ion sources of the metals constituting the target plating film. For example, in the case of forming a Ni-Cr-(Mo / W) alloy film, it refers to the total molar amount of nickel, chromium, and molybdenum and / or tungsten; in the case of 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. For example, it does not include the amount of metals that do not constitute the plating film, such as alkali metals in molybdates. It usually refers to the total molar amount of metals from Groups III to XV, such as Groups IV to XIV, in the plating solution.

[0044] <Chemical species such as ammonia>

[0045] The plating solution of this embodiment, together with the metal ion source, contains one or more chemical species selected from the group consisting of ammonia, amine, and ammonium ions. A plating solution containing such a chemical species exhibits excellent uniform electrodeposition properties, enabling the formation of nickel-based alloy coatings with a more uniform film thickness. It should be noted that this effect is independent of which component of the plating solution the aforementioned chemical species originates from, such as a pH adjuster or a conductive salt.

[0046] In this embodiment, the aforementioned chemical species can be derived from one or more supply sources selected from the group consisting of ammonia, alkylamines, and ammonium salts. There are no particular limitations on the type of supply source. The plating solution of this embodiment can be obtained, for example, by mixing a metal ion source or additive containing ammonia, amines, and / or ammonium ions. For example, ammonium chromate or ammonium molybdate can be used as the metal ion source, or a pH adjuster or conductive salt containing ammonia, amines, or ammonium salts can be added. Alternatively, it can be prepared by using substances that do not contain ammonia, amines, or ammonium ions as the metal ion source, pH adjuster, and conductive salt, and further mixing in other components containing ammonia, amines, and / or ammonium ions.

[0047] (ammonia)

[0048] In the case where the plating solution of this embodiment contains ammonia, it is preferable to use aqueous ammonia as the supply source. Ammonia is a liquid at room temperature, making it easy to handle and minimizing the possibility of reduced plating solution production efficiency. Furthermore, since various commercially available products are readily available, this is also preferable from a cost-saving perspective. There are no particular limitations on the type of ammonia that can be used; for example, a general-purpose product with an ammonia concentration of 20–40% by mass, particularly 25–35% by mass, can be used.

[0049] (amine)

[0050] The amines used in this embodiment are not particularly limited. Examples include monomethylamine, monoethylamine, monopropylamine, monobutylamine, monohexylamine, monooctylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, methyldiethylamine, ethyldimethylamine, piperidine, and other alkylamines; pyridine, methylpyridine, ethylpyridine, dimethylpyridine, imidazole, bipyridine, and other aromatic amines; monoethanolamine, monoethanolamine, triethanolamine, triethanolamine, and other hydroxyl-containing amines; and DBU, but are not limited to these.

[0051] From an operational and cost-effectiveness standpoint, alkylamines, particularly trialkylamines such as trimethylamine and triethylamine, are preferred. Multiple amines can also be used in combination. Additionally, mixtures containing ammonia and ammonium ions can be used as the amine supply source.

[0052] (Ammonium ion)

[0053] There are no particular restrictions on the types of ammonium ions. For example, besides those produced by NH4+, other types include... + Besides the narrow definition of ammonium ions represented by the chemical formula, other examples include alkyl ammonium ions such as tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, and piperidinium ion; and aromatic ammonium ions such as pyridinium ion and imidazoline ion, but these are not limited to these.

[0054] These ammonium ions can be obtained by dissolving ammonium salts or bases with inorganic ions such as hydroxyl anions, halogen ions such as chloride ions, sulfate ions, nitrate ions, and phosphate ions, or organic ions such as acetate anions, in the plating solution. Ammonium compounds in the narrow sense, such as ammonium hydroxide (NH4OH), ammonium sulfate, ammonium phosphate, and ammonium acetate, are preferred; tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and their sulfate and halide salts, especially ammonium hydroxide and / or ammonium sulfate. These ammonium compounds have high water solubility and low cost, making them suitable as raw materials for plating solutions.

[0055] Ammonium ions can also be formed by adding ammonia or amine to the plating solution. In this embodiment, the pH of the plating solution is not particularly limited, but to further improve uniform electrodeposition, the pH of the plating solution is preferably in the range of 0.5 to 12, for example, preferably in the range of 0.5 to 10, more preferably in the range of 0.5 to 7.5, further preferably in the range of 1.0 to 6.0, and particularly preferably in the range of 2.0 to 4.0. In a plating solution under such acidic conditions, for example, when ammonia or amine is mixed in as a pH adjuster, at least a portion of it naturally becomes ammonium ions. In this embodiment, the plating solution preferably contains both ammonia and / or amine and ammonium ions, and particularly preferably contains ammonia and ammonium ions in the narrow sense as the aforementioned chemical species.

[0056] In the plating solution of this embodiment, the concentration of the aforementioned 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 0.01 to 10.0 mol / L, more preferably 0.05 to 5.0 mol / L, and particularly preferably 0.1 to 3.0 mol / L. At such a concentration, it is easier to form a nickel-based alloy coating with a more uniform composition and film thickness.

[0057] It should be noted that this invention is not limited by any specific theory, but it is believed that these chemical species may play a role in suppressing changes in ion concentration and pH in the plating solution. Due to the presence of these chemical species, changes in the liquid state during the plating process are suppressed, and as a result, electrodeposition performance may be improved.

[0058] Solvent

[0059] In the plating solution of the present invention, water is preferably the solvent containing the metal ion source and the aforementioned chemical species. It may also contain alcohols such as methanol and ethanol; ethers such as tetrahydrofuran (THF), dioxane, and various glycol dimethyl ethers; carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl 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.

[0060] <Additives>

[0061] In the plating solution of this embodiment, various additives such as complexing agents, conductivity-improving agents (primarily conductive salts), pH adjusters, pH buffers, hydrogen generation inhibitors, dispersants, dispersing aids, emulsifiers, surfactants, gloss agents, antioxidants, viscosity modifiers, wetting agents, and pigments can be mixed with the metal ion source and the aforementioned chemical species. It should be noted that, as described above, ammonia, amines, and / or ammonium ions can also be added as conductive salts or pH adjusters. For example, these additives are already present in plating solutions containing ammonium sulfate as a conductive salt or ammonia as a pH adjuster, but other types of conductive salts or pH adjusters can be further added.

[0062] Among the additives mentioned above, the uniform electrodeposition properties of the plating solution can be further improved by combining complexing agents, conductive salts, pH adjusters, and pH buffers. Complexing agents, in particular, are additives that also contribute to improved electrodeposition properties. Several of these additives will be described below.

[0063] <Complexing Agents>

[0064] The plating solution of this embodiment preferably contains a complexing agent along with the metal ion source and the aforementioned chemical species. In this embodiment, the complexing agent can be of any type, and conventional complexing agents can be used. It should be noted that the aforementioned ammonia and amines can form complexes with transition metals such as nickel and chromium depending on the conditions, but they cannot form complexes under various conditions, including acidic conditions. Therefore, in this embodiment, the aforementioned chemical species are considered to be outside the scope of the complexing agent.

[0065] Specifically, examples of complexing agents include cyanides; various carboxylic acids and their salts; various amino acids and their salts; phosphorus-containing compounds such as pyrophosphates, trimethylphosphonic acid and their salts, and tris(3-hydroxypropyl)phosphine; sulfur-containing compounds such as thiourea, mercaptoacetic acid, thiodiethanolic acid, thioethylene glycol, thiodiglycol, mercaptosuccinic acid, 3,6-dithia-1,8-octanediol, 3,6,9-trithiadecane-1,11-disulfonic acid, thiobis(dodecylethylene glycol), di(6-methylbenzothiazolyl)disulfide trisulfonic acid, di(6-chlorobenzothiazolyl)disulfide disulfonic acid, dithiodiphenylamine, dipyridyl disulfide, mercaptosuccinic acid, sulfites, and thiosulfates; alcohols; and ethylenediamine, ascorbic acid, gluconolactone, gluconolactone, etc., but are not limited to these. Multiple complexing agents can also be used in combination.

[0066] Furthermore, as a complexing agent, one or more selected from the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylate salts, amino acids, amino acid salts, and alcohols are preferred. If the plating solution contains an appropriate amount of such a complexing agent, the uniformity of electrodeposition can be further improved. Among these, carboxylic acids, hydroxycarboxylic acids, and their salts are particularly preferred, with hydroxycarboxylic acids being particularly preferred. These complexing agents will be described in more detail below, but the complexing agents that can be used as components of the plating solution in this embodiment are not limited to those described below.

[0067] (Carboxylic acids and their salts)

[0068] Examples of 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. Examples of their sodium, potassium, and ammonium salts are also suitable. It should be noted that salts of carboxylic acids with multiple carboxyl groups can be salts where only some of the carboxyl groups form the salt, or double salts, such as sodium hydrogen oxalate and potassium sodium oxalate.

[0069] (Hydroxycarboxylic acids and their salts)

[0070] Examples of suitable hydroxycarboxylic acids as complexing agents include glycolic acid, gluconic acid, citric acid, glucoheponic acid, tartaric acid, and diethylene glycol. Examples of their sodium, potassium, and ammonium salts include hydroxycarboxylic acid salts. For example, sodium hydrogen tartrate and potassium sodium tartrate are suitable candidates.

[0071] (Amino acids and their salts)

[0072] Examples of suitable amino acids (aminocarboxylic acids) as chelating agents include glycine, α-alanine, β-alanine, cysteine, anthranilic acid, aspartic acid, glutamic acid, aminodiacetic acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraaminehexaacetic acid (TTHA), ethylenedioxybis(ethylamine)-N,N,N',N'-tetraacetic acid, and aromatic amino acids such as pyridine dicarboxylic acid. Examples of amino acid salts include their sodium, potassium, and ammonium salts.

[0073] (alcohol)

[0074] Alcohols suitable as complexing agents include, for example, glycols such as ethylene glycol, propylene glycol, and diethylene glycol.

[0075] (Complexing dose)

[0076] In the plating solution of this embodiment, the amount of complexing agent relative to the total amount of metal ion source is preferably 0.01 equivalents or more and 4 equivalents or less. By setting the ratio of complexing agent dosage to metal ion source dosage in the range of 0.01 to 4 equivalents, the uniform electrodeposition properties of the plating solution can be further improved, resulting in a nickel alloy coating with more uniform film thickness.

[0077] In alloy plating, since multiple metals with different deposition potentials are typically used, complexing agents with a metal ion source amount of more than 100% are usually used to form the desired type of alloy film with a uniform composition. In this study, when forming a plating film from a plating bath containing the aforementioned chemicals, by using a relatively small amount of complexing agent (0.01 to 4 equivalents relative to the total amount of metal ion source), an unexpected effect of further improving the electrodeposition properties of the plating bath was observed.

[0078] Here, "equivalent" refers to the ratio of the molar amount of the complexing agent molecules to the total molar amount of the metal ions constituting the coating. It should be noted that "total amount of metal ion sources," as mentioned above, is the sum of the molar amounts of all ion sources of the metal constituting the target coating, 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.

[0079] In the plating solution of this embodiment, as described above, it is preferable that the molar ratio of the complexing agent to the total amount of the metal ion source, i.e., the complexing agent dosage / total metal ion source, is 0.01 equivalents or more and 4 equivalents or less. More preferably, the molar ratio of the complexing agent dosage / total metal ion source is, for example, 0.05 equivalents or more, further 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. In addition, this molar ratio is preferably 3.0 equivalents or less, more preferably 2.0 equivalents or less, particularly preferably 1.0 equivalents or less, further preferably 0.8 equivalents or less or 0.6 equivalents or less, for example, 0.10 to 2.0 equivalents, of which 0.20 to 1.5 equivalents, further preferably 0.30 to 1.0 equivalents, and particularly preferably 0.40 to 0.90 equivalents.

[0080] By appropriately selecting the molar ratio of complexing agent dosage to total metal ion source within the range of 0.01 to 4, based on the type of target coating or the type of complexing agent, uniform electrodeposition can be further improved. It should be noted that the concentration of the complexing agent in the plating solution is mainly determined based on the total concentration of the metal ion source, and is typically preferably 0.01 to 1 mol / L, and particularly preferably 0.1 to 0.8 mol / L.

[0081] (Conductive salt)

[0082] 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. Sulfates and / or ammonium salts are preferred, and these inorganic salts are particularly preferred. If the plating solution contains sulfates or ammonium salts as conductive salts, it can promote the uniform precipitation of the metal to form the target coating, making it easier to form an alloy coating with more uniform composition and film thickness. Furthermore, when the conductive salt is an ammonium salt, it also serves as a source of the aforementioned chemical species.

[0083] Specific examples of preferred conductive salts include sodium sulfate, potassium sulfate, ammonium sulfate, ammonium chloride, ammonium bromide, ammonium nitrate, and ammonium phosphate, but are not limited to these. Among them, sodium sulfate, potassium sulfate, and ammonium sulfate are preferred, and ammonium sulfate is particularly preferred.

[0084] There are no particular restrictions on the concentration of these conductive salts in the plating solution, and they can be set to the desired value based on the concentration of the metal components, etc. For example, a concentration of 0.1 to 3 mol / L, or more specifically, 0.25 to 2 mol / L, can be used, but it is not limited to such a range.

[0085] (pH adjuster)

[0086] In order to further improve the uniform electrodeposition properties, the plating solution of this embodiment may contain a pH adjuster to adjust the pH to a region suitable for nickel-based alloy plating, for example, to a level of 0.5 to 12, wherein the pH is 0.5 to 10, more preferably 0.5 to 7.5, further preferably 1.0 to 6.0, and particularly preferably 2.0 to 4.0.

[0087] pH adjusters are particularly useful when using complexing agents. Complexing agents each have a pH level at which they readily form complexes, therefore it is preferable to adjust the pH of the plating solution before use. Alternatively, the plating solution can be maintained at a specific temperature and pH for a certain period of time; this process is also known as "aging." In such cases, it is preferable to use a pH adjuster.

[0088] There are no particular limitations on the pH adjuster added to the plating solution in this embodiment, and various acids and / or bases can be used depending on the pH during the plating process or aging. Here, it is preferable to use a pH adjuster containing sulfuric acid as an acid, or a pH adjuster containing alkali metal hydroxides, ammonia, and / or amines as bases, as this results in improved conductivity of the plating solution. When the pH adjuster contains ammonia, amines, and / or ammonium ions, this pH adjuster also serves as a source of the aforementioned chemicals.

[0089] (pH buffer)

[0090] In this embodiment, the plating solution preferably also includes a pH buffer to stabilize the precipitation reaction of the target metal. It should be noted that the pH buffer can also be considered a type of pH adjuster in a broad sense, but it is treated here as a component different from a pH adjuster in a narrow sense. There is no particular limitation on the type of pH buffer; a buffer suitable for the target pH range can be selected from various known pH buffers. Examples include boric acid, phosphoric acid, citric acid, acetic acid, tartaric acid, and their salts, but it is not limited to these. When the pH buffer contains ammonia, amine, and / or ammonium ions, the pH buffer also serves as a source of these chemicals.

[0091] (Hydrogen production inhibitor)

[0092] The plating solution of this embodiment may also contain a hydrogen generation inhibitor. By including a hydrogen generation inhibitor in the plating solution, it is easy to suppress the decrease in current efficiency during the plating process. In addition, the generation of hydrogen gas at the cathode can be suppressed, thereby easily preventing scorching and hydrogen embrittlement of the plating film. It should be noted that scorching (burning) is an undesirable situation where the current density at the cathode is too high, resulting in the formation of a rough and brittle plating film. It is a phenomenon caused by the precipitation of metal hydroxides, etc., accompanied by an increase in pH at the cathode interface. There are no particular limitations on the hydrogen generation inhibitor, and various known hydrogen generation inhibitors 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.

[0093] When hydrogen generation inhibitors are present, their concentration is preferably in the range of 0.01 to 2.0 mol / L, and particularly preferably in the range of 0.1 to 1.5 mol / L. It should be noted that some of these hydrogen generation inhibitors can also function as complexing agents and pH buffers. Therefore, by setting the concentration of, for example, citric acid in the plating solution to the range of 0.01 to 2.0 mol / L, further to the range of 0.02 to 1.5 mol / L, and particularly to the range of 0.10 to 1.0 mol / L, the functions of complex formation, pH adjustment, and hydrogen generation inhibition can all be achieved.

[0094] (Gloss agent)

[0095] The plating solution of this embodiment may contain a glossing agent. The glossing agent not only imparts gloss to the plating film but also sometimes promotes the precipitation of metal in the recesses and smooths the plating surface. There are no particular limitations on the type of glossing agent; various aldehydes, triazines, imidazoles, indoles, quinolines, 2-vinylpyridine, aniline, phenanthrene, new cuprous reagents, pyridinecarboxylic acid, thioureas, benzothiazoles, thioethers, etc., can be used. When a glossing agent is included, its concentration is preferably from 0.01 mg / L to 500 mg / L, and particularly preferably from 0.1 mg / L to 10 mg / L.

[0096] (surfactant)

[0097] There are no particular limitations on the surfactant used; a desired surfactant can be selected from common anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. When a surfactant is present, its concentration is preferably between 1 mg / L and 50 g / L, and particularly preferably between 5 mg / L and 10 g / L.

[0098] (Antioxidants)

[0099] Antioxidants are used to prevent the oxidation of metal salts. Examples of antioxidants include hypophosphite, ascorbic acid, phenol sulfonic acid, cresol sulfonic acid, hydroquinone sulfonic acid, hydroquinone, α- or β-naphthol, catechol, resorcinol, phloroglucinol, hydrazine, phenol sulfonic acid, catechol sulfonic acid, hydroxybenzene sulfonic acid, naphthol sulfonic acid, and their salts, but are not limited to these. Antioxidants can be contained at concentrations, for example, from 0.1 g / L to 500 g / L, particularly from 1 g / L to 100 g / L.

[0100] The above describes several representative additives, but the plating solution of the present invention may contain various additives in addition to these. Furthermore, one or two additives may also be used as functional agents that provide multiple effects. As mentioned above, some pH adjusters and conductive salts can also be sources of the aforementioned chemicals. In addition, for example, 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 be used to exhibit various functions such as conductivity imparting, pH adjustment, buffering, and hydrogen production inhibition. The present invention also includes a plating solution for forming Ni-Cr-(Mo / W) alloy coatings containing inorganic acid salts and / or organic acid salts.

[0101] <Preparation of plating solution>

[0102] The plating solution of the present invention can be prepared using conventional methods from the components described above. The details can be appropriately determined by considering the composition and mixing amount of each component. In particular, when the plating solution contains complexing agents, pH adjustment and "aging" treatment can be performed before use.

[0103] 2. Methods for forming alloy coatings

[0104] By using the plating solutions described in the various embodiments above for plating treatment, a desired Ni-Cr-(Mo / W) alloy coating can be formed on various substrates. Therefore, a method for forming a Ni-Cr-(Mo / W) alloy coating can be defined as a method that includes the step of plating treatment using the aforementioned plating solutions. According to such a method, a nickel alloy coating with excellent uniform electrodeposition properties and uniform film thickness can be formed.

[0105] There are no particular restrictions on the methods and conditions for plating. Depending on the type of nickel alloy coating and the substrate to be plated, conventional electrolytic plating can be performed under the usual conditions.

[0106] Specifically, the temperature of the plating bath can be set to between 10 and 90°C. Additionally, the current density can be set to between 0.01 and 50 A / dm³. 2 The degree of.

[0107] <Overview of Plating Processing>

[0108] The coating on nickel-based alloys can be formed, for example, by immersing the object to be plated as a cathode in the plating solution of the present invention along with the anode and passing an electric current through it. Here, the solution temperature is 10°C or higher, and the current density is 0.01 A / dm³. 2 The above conditions facilitate the formation of a nickel-based alloy coating in a relatively short time. If the liquid temperature is below 90°C, changes in concentration caused by evaporation and boiling of the plating solution are suppressed, resulting in a more uniform nickel-based alloy coating in terms of composition and thickness. Furthermore, if the current density is 50 A / dm³... 2 The following methods can easily suppress defects such as scorching in the generated alloy coating. It should be noted that the plating solution in the plating tank is sometimes referred to as the "plating bath", but in this embodiment, the two are considered to be the same and are referred to as the "plating solution".

[0109] (Object to be plated)

[0110] In this embodiment, the object to be plated can be any material as long as it is conductive. Various metal materials and conductive ceramic materials are not excluded, but materials that have become conductive through processes such as electroless plating or metal vapor deposition, such as non-conductive ceramics, glass, carbon materials, resins, rubber, and wood, can also be used. When plating conductive materials such as metals, materials with other plating layers attached to the substrate can also be used. The shape of the object to be plated is not particularly limited.

[0111] Considering the excellent heat resistance and corrosion resistance of Ni-Cr-(Mo / W) alloys, represented by Hastelloy, the alloy coating formation method of this embodiment is particularly effective when the object to be coated 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 a material obtained by chromium plating, nickel plating, etc., on such substrates, a material with particularly excellent heat resistance and corrosion resistance can be produced. Depending on the target operating temperature, a metal layer can also be pre-formed on the surface of a heat-resistant resin material, such as a thermosetting polyimide or its fiber composite material, through electroless plating, for use in the coating treatment of this embodiment. Polymer materials treated by the coating method of this embodiment can be effectively used as lightweight corrosion-resistant materials.

[0112] (anode)

[0113] There are no particular restrictions on the anode used in the plating process. For example, electrodes made of nickel or nickel-based alloys can be used as anodes, and nickel, as well as chromium, molybdenum, etc., can be supplied to the plating bath during the process. However, in order to achieve stable plating 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 alloys, boron-doped diamond, graphite, etc., as anodes. These anodes do not dissolve into the plating solution during the process, or even if they do, the dissolution is minimal, thus preventing changes in the composition of the plating solution. As a result, a more homogeneous alloy film is more easily formed.

[0114] <Practical Applications of Plating Treatment>

[0115] The following provides a more detailed explanation of the plating process for forming nickel alloy films on various conductive or non-conductive substrates.

[0116] (Preprocessing)

[0117] The substrate to be plated can be pretreated, for example, by degreasing or acid activation, before performing the plating process of this embodiment. Especially when plating general non-conductive materials such as ceramics and resins, it is preferable to perform pretreatment such as electroless plating, sputtering, or vapor deposition to form a metal layer or graphite layer on the surface and impart conductivity.

[0118] There are no particular limitations on the pretreatment method; any desired method can be used depending on the substrate used. Taking the common electroless plating process on a non-conductor as an example, a more specific implementation will be described. For instance, after arbitrarily degreasing and cleaning the surface of the substrate to be treated, etching is performed, followed by contact with a catalyst-attributing enhancement solution (conditioning). Next, a catalyst such as palladium is applied by contacting the catalyst-attributing treatment solution, and the catalyst is activated arbitrarily using an inorganic acid, reducing agent, etc., to perform electroless nickel plating, electroless copper plating, electroless cobalt plating, etc.

[0119] It can further perform impact plating treatments such as copper impact plating, nickel impact plating, silver impact plating, and gold impact plating on substrates after electroless plating; and general plating treatments such as nickel plating, chromium plating, nickel-chromium plating, tin plating, tin-silver plating, copper plating, gold plating, and silver plating.

[0120] It should be noted that when the substrate is a conductive material such as metal or conductive ceramic, the above-mentioned degreasing, etching, impact plating, and general plating treatments can also be performed as desired.

[0121] (Plating process)

[0122] The pretreated substrate is then plated in the plating solution of this invention. During the plating process, as described above, it is preferable to set the solution temperature to 10–90°C and the current density to 0.01–50 A / dm³. 2 More preferably, the liquid temperature is set to 20–80°C, particularly 25–70°C, and the current density is set to 0.1–20 A / dm³. 2 Especially when set to 1-10 A / dm 2 The degree of plating is determined by the type of nickel alloy coating being applied, the liquid temperature during the process, and the current density. It is preferably set to approximately 1 to 300 minutes, and more particularly 3 to 120 minutes.

[0123] It should be noted that the appropriate pH of the plating solution during the plating process varies depending on the type of nickel-based alloy coating and the composition of the plating solution used. For example, it may be in the range of 0.5–12 or 0.5–10, with a range of 0.5–7.5, further ranging from 1.0–6.0, and particularly from 2.0–4.0. By performing the plating process under such conditions, it is easy to form Ni-Cr-(Mo / W) alloy coatings with excellent uniformity in composition and film thickness, such as nickel-based alloy coatings with the composition of Hastelloy. Furthermore, during this plating process, it is preferable to agitate the liquid using methods such as aeration, pump circulation, or paddle stirring.

[0124] (Post-processing)

[0125] Plated parts with a nickel-based alloy coating as described above can be used directly, or an electrochemical conversion treatment film and / or an immersion chemical conversion treatment film can be further applied to the alloy coating. Ni-Cr-(Mo / W) alloy coatings generally have excellent heat resistance and corrosion resistance, but the corrosion resistance of the plated parts can be further improved by treatment films. There are no particular limitations on electrochemical conversion treatment and immersion chemical conversion treatment; conventional treatment methods can be applied as desired. Examples include chromate treatment, wax treatment, treatment using solutions such as benzotriazole or triazine thiol, treatment using solutions containing amino or imine compounds, anodizing, and heat treatment, but these are not limited to these.

[0126] 3. Plated Components

[0127] The plating method of this embodiment, as described above, enables the formation of Ni-Cr-(Mo / W) alloy coatings with excellent uniformity in film thickness and other properties on various substrates. Hereinafter, embodiments of plating parts manufactured using the above-described plating solution and plating parts manufactured using the above-described plating method will be described.

[0128] The plated part of this embodiment exhibits excellent heat resistance and corrosion resistance derived from the coating of Ni-Cr-(Mo / W) alloys. Furthermore, any material can be used as the substrate. Therefore, materials with good machinability, such as iron and stainless steel, can be used as substrates to produce plated parts that possess complex and fine shapes while exhibiting excellent heat resistance and corrosion resistance at a low cost. Lightweight, corrosion-resistant materials can also be produced by plating various shapes of polymer materials, particularly heat-resistant polymer materials based on polyimide, etc. According to the present invention, various plated parts of various shapes, including industrial materials, automotive parts, building material parts, household appliance parts, and electronic parts, are provided, exhibiting excellent heat resistance and corrosion resistance.

[0129] Example

[0130] The present invention will be further described in detail below by way of examples, but the present invention is not limited thereto in any way described herein.

[0131] Example 1

[0132] Sulfuric acid and ammonia were added to the following aqueous solution to adjust the pH to 2.5, thus preparing the plating solution (ammonia and / or ammonium ion concentration: 0.25 mol / L). In this plating solution, a degreased and acid-activated copper plate (67 mm x 100 mm Hull cell copper plate) was immersed as the cathode, and IrO2 / Ti was used as the anode for a Hull cell test. The test was conducted for 5 minutes at a solution temperature of 50°C and a current of 3A. The appearance after the test is illustrated in the following photographs. Figure 1 The width of the area where the coating is formed (covering the low current density side to the high current density side) (plating capacity: 100 mm maximum) and the average film thickness of the coating at each current density based on the Hull cell test are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0133] [Composition of the medicinal solution in Example 1]

[0134] NiSO4·6H2O 0.02mol / L

[0135] • Alkaline chromium sulfate 0.30 mol / L

[0136] ·Na₂MoO₄·2H₂O 0.02mol / L

[0137] · Gluconic acid 0.30 mol / L

[0138] ·Na₂SO₄ 1.0 mol / L

[0139] ·H3BO3 1.0mol / L

[0140] The amount of complexing agent relative to the total amount of metal ion source is 0.88 equivalents.

[0141] Examples 2-3

[0142] The amount of complexing agent relative to the total amount of metal ion source was set to 3.0 equivalents (Example 2) or 4.0 equivalents (Example 3), and otherwise, the same procedures as in Example 1 were performed. The appearance photographs after the experiment in Example 2 are illustrated below. Figure 2 The plating uniformity and average film thickness of the deposited films at various current densities in Examples 2 and 3 are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0143] Comparative Example 1

[0144] Using an aqueous solution of sodium hydroxide instead of ammonia, the same procedures as in Example 2 were performed. The resulting photographs are shown in the figure. Figure 3 The plating uniformity and the average film thickness of the plated film at various current densities are shown in Table 1 below, and the content of each metal element is shown in Table 2 below.

[0145] Example 4

[0146] The same procedures as in Example 1 were performed using the solution (aqueous solution) with the following composition. The results of the plating uniformity and film thickness measurements are shown in Table 1 below, and the contents of each metal element are shown in Table 2 below.

[0147] [Composition of the medicinal solution in Example 4]

[0148] NiSO4·6H2O 0.02mol / L

[0149] • Alkaline chromium sulfate 0.30 mol / L

[0150] ·Na₂MoO₄·2H₂O 0.02mol / L

[0151] · Gluconic acid 0.30 mol / L

[0152] ·NaCl 1.0mol / L

[0153] ·H3BO3 1.0mol / L

[0154] The amount of complexing agent relative to the total amount of metal ion source is 0.88 equivalents.

[0155] Comparative Example 2

[0156] The following aqueous solution was used, along with a Ni anode, and the operation was otherwise largely the same as in Comparative Example 1. The pH of the plating solution was adjusted to 2.8 by adding sulfuric acid and sodium hydroxide aqueous solution. Photographs of the appearance after the test are shown in the figure. Figure 4 The results of the plating uniformity and film thickness measurements are shown in Table 1 below, and the contents of each metal element are shown in Table 2 below.

[0157] [Composition of the drug solution in Comparative Example 2]

[0158] ·NiCl2 0.042mol / L

[0159] ·CrCl3 0.19mol / L

[0160] ·Na₂MoO₄·2H₂O 0.17mol / L

[0161] Sodium gluconate 0.16 mol / L

[0162] Formic acid 0.78 mol / L

[0163] · Glycine 0.67 mol / L

[0164] ·H3BO3 0.29mol / L

[0165] ·NaCl 1.0mol / L

[0166] The amount of complexing agent relative to the total amount of metal ion source: 4.0 equivalents

[0167] Example 5

[0168] The following aqueous solution was used, and the pH was adjusted to 2.5 using a sodium hydroxide aqueous solution in conjunction with sulfuric acid. Otherwise, the same procedures as in Example 1 were performed. That is, the plating solution in this example contains ammonium ions derived from the conductive salt rather than from the pH adjuster. The results of the plating uniformity and film thickness measurements are shown in Table 1, and the content of each metal element is shown in Table 2.

[0169] [Composition of the medicinal solution in Example 5]

[0170] NiSO4·6H2O 0.02mol / L

[0171] • Alkaline chromium sulfate 0.30 mol / L

[0172] ·Na₂MoO₄·2H₂O 0.02mol / L

[0173] · Gluconic acid 0.30 mol / L

[0174] ·(NH3)2SO4 1.0mol / L

[0175] ·H3BO3 1.0mol / L

[0176] The amount of complexing agent relative to the total amount of metal ion source is 0.88 equivalents.

[0177] [Table 1]

[0178] [Table 2]

[0179] In Examples 1-5, which used plating solutions containing ammonia or ammonium ions according to the present invention, the plating uniformity was 80 mm or more, demonstrating good uniform electrodeposition. Furthermore, a plating film with almost no scorching or discoloration was obtained. Generally, suppressing scorching and discoloration is more important than ensuring film thickness. Even in Comparative Example 1, which did not contain ammonia or ammonium ions, the plating uniformity was good at 88 mm, but scorching and discoloration were noticeable on the high current density side. In Comparative Example 2, the plating uniformity was significantly poor at 39 mm, and scorching and discoloration were observed on the low current density side. Moreover, even on the high current density side, the amount of Mo precipitation was very small, making it difficult to classify the resulting plating film as a Ni-Cr-Mo alloy film.

[0180] Furthermore, in the embodiments of this application, the difference in film thickness accompanying the difference in current density is also small. In Comparative Example 2, the film thickness varied significantly with each current density, which, taking into account, suggests that the plating solution according to the present invention can reduce film thickness deviations caused by plating conditions. This tendency is particularly significant in Examples 1, 4, and 5, where the complexing agent equivalent is 1 or less. In addition, in Examples 1, 4, and 5, a uniform plating weight of nearly 100 mm was measured, indicating that when the complexing agent equivalent is 2 or less, for example, 1 or less, particularly excellent uniform electrodeposition can be exhibited.

[0181] As described above, according to the present invention, a plating solution and plating method with excellent uniform electrodeposition properties are provided, enabling the formation of Ni-Cr-(Mo / W) alloy coatings with a more uniform film thickness. According to the present invention, nickel alloy coatings with compositions such as HASTELLOY can also be formed with uniform composition and thickness on the surface of components of various shapes and materials, producing lightweight, low-cost coated parts with excellent heat resistance and corrosion resistance.

Claims

1. A plating solution for forming a Ni-Cr-(Mo / W) alloy coating, comprising: a metal ion source including nickel, chromium and molybdenum and / or tungsten ions; and one or more chemical species selected from the group consisting of ammonia, amine and ammonium ions.

2. The plating solution as claimed in claim 1, further comprising a complexing agent in an amount of 0.01 equivalents to 4 equivalents relative to the total amount of the metal ion source.

3. The plating solution as described in claim 1 or 2, wherein, The chemical species are derived from one or more supply sources selected from the group consisting of ammonia, alkylamines and ammonium salts.

4. The plating solution as described in claim 1 or 2, further comprising a conductive salt.

5. The plating solution as described in claim 4, wherein, The conductive salt is a sulfate and / or a halide salt.

6. The plating solution as described in claim 1 or 2, further comprising organic acid salts and / or inorganic acid salts.

7. The plating solution as described in claim 2, wherein, The complexing agent is selected from one or more of the group consisting of carboxylic acids, carboxylates, hydroxycarboxylic acids, hydroxycarboxylates, amino acids, amino acid salts, and alcohols.

8. The plating solution as described in claim 1 or 2, further comprising a pH buffer.

9. The plating solution as described in claim 1 or 2, wherein, The concentration of nickel is in the range of 0.001 mol / L to 0.5 mol / L (elemental conversion), the concentration of chromium is in the range of 0.01 mol / L to 1.5 mol / L (elemental conversion), and the combined concentration of molybdenum and tungsten is in the range of 0.001 mol / L to 2.0 mol / L (elemental conversion).

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

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