JPH0368785A - Formation of black nickel-phosphorus alloy coating film by electroless plating - Google Patents

Abstract

PURPOSE:To form a uniform and homogenous black film independently of the shape of a base material by forming a film on the surface of the base material with an electroless Ni-P alloy plating bath contg. an added nitrogen compd. and subjecting the formed film to oxidation treatment with an acidic soln. contg. a ferric salt. CONSTITUTION:The surface of a base material is subjected to electroless Ni-P alloy plating with an electroless Ni-P alloy plating bath contg. an added nitrogen compd. A formed alloy film is subjected to oxidation treatment with an acidic soln. contg. a ferric salt. The nitrogen compd. used may be selected from among prim., sec. and tert. amines and heterocyclic compds. each contg. nitrogen in the ring. A uniform and homogenous black film having a fine color tone can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of forming a black electroless nickel-phosphorous alloy coating.

Conventional technology and its problems Currently, black films are widely used in optical equipment such as cameras and analytical instruments, transmission paths for optical communications, collectors for solar heat collectors, and decorative items. As the black film, for example, a black nickel film formed by electrolysis, a black chromium film, a black zinc film formed by chemical conversion treatment, a dyed or black painted film, etc. are generally used. However, these black films may have insufficient color tone, uniformity, dimensional accuracy, etc., may not be able to form depending on the material or shape, or may have poor hardness, corrosion resistance, abrasion resistance, etc.
There are various problems such as low weather resistance and heat resistance.

On the other hand, electroless nickel-phosphorus alloy plating can be used to plate not only metal materials such as aluminum, iron, copper, and other alloys, but also non-metals such as plastics, rubber, and ceramics by using a catalyst. , uniform film thickness,
It has the advantage of providing properties such as high hardness, excellent corrosion resistance, and wear resistance. Taking note of this advantage, attempts have been made to obtain a black film by oxidizing the film.

For example, a method of forming a phosphorus-nickel alloy film and then immersing the film in a permanganate acid bath (Japanese Patent Publication No. 59-2
No. 2786), a method of oxidizing the acid film after forming a nickel film containing 7% or less of phosphorus (Japanese Patent Publication No. 64-715
No. 3) etc. have been proposed. However, none of these methods can form a uniform black film depending on the shape of the material, and the color tone, hardness, corrosion resistance, abrasion resistance, weather resistance, heat resistance, etc. of the black film are not sufficient. I can not say.

Means for Solving the Problems The present inventor has conducted extensive research in view of the problems of the above-mentioned prior art. As a result, a uniform and homogeneous black film can be formed regardless of the shape of the material.The resulting black film has a beautiful color tone, has excellent hardness, corrosion resistance, abrasion resistance, weather resistance, heat resistance, etc. We have discovered a method that allows electrolytic nickel to be applied to all possible materials, and have completed the present invention.

That is, the present invention forms an electroless nickel-phosphorus alloy film on the surface of a material in an electroless nickel-phosphorus alloy plating bath containing a nitrogen compound, and then oxidizes the alloy film with an acidic solution containing a ferric salt. The present invention relates to a method for forming a black electroless nickel-phosphorus alloy film, which is characterized by a treatment.

According to the method of the present invention, first, nickel-phosphorus alloy plating is applied to the surface of the material using an electroless nickel-phosphorus alloy plating bath containing a nitrogen compound. At this time, the material may be previously subjected to treatments such as degreasing, electrolytic degreasing, and acid activation according to conventional methods. The electroless nickel-phosphorus plating solution used in this step is not particularly limited, and any known solution can be used. Examples include those containing components such as nickel salts, hypophosphites, complexing agents, accelerators, stabilizers, and wetting agents. Specific examples of each of the above components are listed below.

Nickel salts: nickel sulfate, nickel chloride, nickel acetate, etc.

・Hypophosphite: Sodium hypophosphite, potassium hypophosphite, etc.

・Complexing agent: Oxycarboxylic acid or its salts such as lactic acid, citric acid, malic acid, glycolic acid, tartaric acid, and gluconic acid.

・Accelerator: formic acid, acetic acid, propionic acid, fumaric acid,
Monocarboxylic acids or dicarboxylic acids such as malonic acid, succinic acid, adipic acid, or their salts/stabilizers...Sulfur compounds (e.g., 2-mercaptoethanol, 2-mercaptobenzothiazole, etc.), heavy metal salts (thallium, cadmium, etc.) lead, etc.).

・Wetting agents: nonionic surfactants, anionic surfactants, etc.

Examples of nitrogen compounds added to the electroless nickel-phosphorus alloy plating solution include nitrogen-containing compounds, such as those listed below.

・Formula R-NH2 (in the formula, R is an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms
Indicates an alcohol residue or a phenyl group. ) Primary amines represented by: for example, monoethylamine, monoethanolamine, aniline, etc.

(In the formula, R1 and R2 are the same or different and have 1 to 1 carbon atoms.
6 alkyl group, an alcohol residue having 1 to 6 carbon atoms, or a carboxylic acid residue. ) Secondary amines represented by
...For example, jetanolamine, dimethylamine, nitrilodiacetic acid, etc.

(In the formula, R1, R2 and R3 are the same or different and represent an alkyl group having 1 to 6 carbon atoms, an alcohol residue having 1 to 6 carbon atoms, or a carboxylic acid residue.) ...For example, triethanolamine, nitrilotriacetic acid, N,N-dimethylacetamide, etc.

Heterocyclic compounds containing nitrogen in the ring, such as pyridine, virol, imidazole, morpholine, O-phenanthroline, etc.

-Amino acids...for example, glycine, alanine, aspartic acid, glutamic acid, leucine, etc.

Nitrogen compounds can be used alone or in combination of two or more. The amount of nitrogen compound added to the electroless nickel-phosphorus alloy plating solution can be appropriately selected from a wide range.
For class amines, nitrogen-containing heterocyclic compounds, etc., the amount is usually 1■/l.
~5g/l or so, preferably 5/i~2g/l,
Secondary amines, tertiary amines, etc. are usually 0.5■/
! ! ~100g/Jl! degree, preferably 0.7■//
! ~10 g/l, amino acids usually 1■/i~10
The amount may be about 0 g/l, preferably about 5 g/i to 20 g/l.

The electroless plating described above is performed under normal conditions. For example, it is carried out at a temperature of about 65 to 80 degrees Celsius for 15 minutes to 80 minutes.
It will finish in about an hour. As a result, a nickel-phosphorus alloy plating film having a thickness of about 3 to 30 μm is formed.

The black film of the present invention can be obtained by oxidizing the nickel-phosphorus alloy plating film formed in this manner with an acidic solution containing a ferric salt.

As the acidic solution containing the ferric salt, a solution obtained by adding the ferric salt to a solution acidified with an appropriate acid can be used. If the ferric salt solution is acidic, it can be used as is. Further, when the ferric salt solution is neutral or alkaline, an acid may be added to make it acidic. The nucleic acid may be any acid, including mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as carboxylic acid and sulfonic acid.

The ferric salt is not particularly limited, and examples thereof include ferric chloride, ferric sulfate, and ferric nitrate.

Ferric salts can be used alone or in combination of two or more. The concentration of ferric salt in the acidic solution is not particularly limited, but
Usually 1g #! ~400 g/l or so, preferably 10~
Approximately 150 g/l is preferable.

Examples of the oxidation treatment method include immersion and anodic oxidation. For example, immersion is usually carried out at a temperature of about 10 to 50°C, preferably about 20 to 30°C, for about 5 seconds to 60 minutes.
Preferably, it may be carried out for about 30 seconds to 5 minutes.

The method of the present invention can be applied to all materials that can be electrolessly plated with nickel.

Effects of the Invention According to the method of the present invention, a uniform and homogeneous black film can be formed regardless of the shape of the material to be plated, and the resulting black film has properties such as hardness, corrosion resistance, abrasion resistance, weather resistance, and heat resistance. Excellent in both. Moreover, since the method of the present invention can be applied to all materials for which electroless nickel can be applied, it is expected that the application will be expanded beyond just those for which black coatings are currently used.

EXAMPLES Examples and comparative examples are given below to further clarify the present invention.

Examples 1 to 4 and Comparative Example 1 Plating solutions having the compositions shown in Table 1 were prepared. Using the plating solution, mild steel plate (JIS G-3141,
5PCC-5B), nickel-phosphorus alloy plating film (
A film thickness of 10 to 20 μm) was formed.

The plating conditions are as follows.

Temperature: 90°C Treatment concentration: 1 dm2/l (100 cm2/l') Time: 60 minutes pH 5.0 (Adjust the pH using sodium hydroxide and sulfuric acid.) The resulting nickel-phosphorus alloy film was treated with the following composition: Oxidation treatment was performed by immersing the sample in a ferric salt solution at room temperature for 1 minute.

Ferric salt solution Ferric chloride 30 g/136% hydrochloric acid 50 g/l According to Examples 1 to 4, good black films were formed in all cases. The film of Comparative Example 1, which was treated with an electroless nickel-phosphorus alloy plating solution containing no nitrogen compound, did not turn black even after the above oxidation treatment.

Example 5 A mild steel plate (SPCC-3B) was degreased, electrolytically degreased, and activated with acid (36% hydrochloric acid 20M#!).

After 1 minute at room temperature, nickel-phosphorus alloy plating was performed in the same manner as in Example 1 using a plating solution having the composition shown in Table 2 below.

Furthermore, a black film was formed in the same manner as in Example 1.

Comparative Example 2 A black film was formed in the following manner according to the method described in Japanese Patent Publication No. 59-22786.

A mild steel plate (SPCC-5B) was degreased, electrolytically degreased, and activated with acid (36% hydrochloric acid 200Tli2#!).

After 1 minute at room temperature, nickel-phosphorus alloy plating was performed under the same plating conditions as in Example 1 using a plating solution having the composition shown in Table 2 below.

This was combined with 20 g/l of sodium permanganate and 96 g/l of sodium permanganate.
The sample was immersed in a bath containing 50 g/l of sulfuric acid at 30° C. for 30 seconds to form a black film.

Comparative Example 3 A black film was formed in the following manner according to the method described in Japanese Patent Publication No. 64-7153.

After degreasing, electrolytic degreasing, and acid activation (36% hydrochloric acid 200W [//! 1 minute at room temperature) of a mild steel plate (SPCC-8B), using a plating solution having the composition shown in Table 2 below, Nickel-phosphorus alloy plating was performed under the same plating conditions as in Example 1.

This was immersed for 10 minutes at 25° C. in a bath containing 100 n of 36% hydrochloric acid to form a black film.

Table 2 In Table 2, All items except stabilizers are g/l.

A heat resistance test and an abrasion resistance test were conducted using the black film obtained above as a sample.

[Heat Resistance Test] After the samples were left for 24 hours at the temperatures listed in Table 3 below, they were judged according to the following criteria.

◎・・・No discoloration or fading ○...Very slightly discolored ×・・・Fading Table 3 The number of times it took to reach 50% was determined.

Test load: 1000g Wheel used: C8-10 The results are shown in Table 4. In Table 4, "untreated" means that the black film was subjected to the test as it was, and "heat treated" means that the black film was subjected to the test after being heat-treated at 300° C. for 1 hour.

Table 4 [Abrasion resistance test] Using a taper abrasion tester [Model 503, manufactured by Teledyne Taper Co., Ltd.], the exposed area of the base was 10% and the above results showed that the black film according to the present invention was superior to the conventional one. It can be seen that it has a good color tone and physical properties.

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Claims (1)

[Claims] (1) After forming an electroless nickel-phosphorus alloy film on the surface of the material in an electroless nickel-phosphorus alloy plating bath containing a nitrogen compound, the alloy film is oxidized with an acidic solution containing a ferric salt. A method for forming a black electroless nickel-phosphorus alloy film, characterized by: