JP2002235193A - Method for forming iron sulfide-based coating with excellent slidability and iron-based material provided with iron sulfide-based coating - Google Patents

Abstract

(57) [Problem] To improve the seizure resistance of an iron sulfide-based film formed by an aqueous solution electrolysis method under a high surface pressure. SOLUTION: An iron-based material is subjected to anodic electrolysis in an aqueous solution containing trivalent iron ions, a chelating agent and a sulfur compound, thereby electrolytically depositing a film substantially composed of iron sulfide on the surface of the iron-based material. A method for forming an iron sulfide-based film having excellent sliding properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an iron sulfide-based coating having excellent slidability on the surface of a sliding part made of an iron-based material. In particular, the present invention relates to a method for electrolytically depositing a preferably 1 to 20 μm-thick iron sulfide-based coating exhibiting stable performance under high surface pressure. Further, the present invention relates to an iron-based material provided with an iron sulfide-based coating. In the present invention, the iron-based material refers to carbon steel for machine structural use, alloy steel, special steel, iron-based cast and forged products, and the like, and carburized therein.
Heat treatment such as nitriding and induction hardening is performed.

[0002]

2. Description of the Related Art Research on the use of iron sulfide coatings for sliding layers
Dating active sulfur (S ⁰ ) back to the iron surface of the material to be processed back to 1953, it was converted from iron sulfides such as FeS and Fe _1-X S and oxides such as Fe ₂ O ₃ and Fe ₃ O ₄ A sulfuration treatment method was developed in France to improve the abrasion resistance by reducing the coefficient of friction in the process of abrasion, making it less likely to adhere to or adhere to the mating material in contact.

[0003] After that, various treatment methods have been studied for the sulfurizing treatment. The typical method is described below. Solid method in which the material to be treated is heated to 400 ° C or higher in a solid processing agent such as FeS and graphite (pack method) After the object to be treated is immersed in a sulfur-based aqueous solution or a low-temperature sulfur-based molten salt, the material is heated to 300 ° C or more Immersion method Sulfur compounds were added to a mixed neutral bath containing sodium chloride as a main component and a mixed reduction bath containing cyanic acid as a main component.
A molten salt method in which the object is immersed in a molten salt bath at 500 ° C or higher. A gas method in which the object is heated at 500 ° C or higher in a mixed gas atmosphere of hydrogen, ammonia, and hydrogen sulfide. Electrolysis method for anodic electrolysis of the workpiece with molten salt

[0004] The wear resistance of the sulfurized layer varies depending on factors such as hardness, material, surface roughness, surface pressure, manner of contact, and type of lubricant on the surface of the sliding member. The hardness of iron sulfide, which is formed by the above method and is expected to exhibit abrasion resistance, is compared with the surface of the carburized and nitrided material.
Due to the considerably low temperature, the iron sulfide coating applied to the low hardness material showed a large mechanical loss during sliding, and the effect of the sulfurizing treatment could not be found.

Accordingly, a treatment method has been developed for simultaneously forming a sulfurized layer and a nitrided layer which are excellent in the wear resistance effect. Based on the nitriding treatment for the purpose of increasing the hardness of a low-hardness material, the friction coefficient is reduced at the same time. In recent years, nitrosulphurizing treatment using a reducing molten salt method, a gas method, and an ion method, which can also perform sulphidation, has been industrialized. These methods will be described.

[0006] One of the methods is a reducing molten salt method in which a sulfuric acid nitriding treatment is carried out in a mixed molten salt obtained by adding a sulfur compound such as sodium thiosulfate or sodium sulfide to a molten salt of cyanic acid and a cyanide compound in an amount of 10% or less. How to However, there are problems in that the bath temperature is as high as 500 ° C. or more and the treatment time is as long as 2 hours or more, and when the sulfur compound in the salt bath is increased, the sulfurized layer becomes thicker and easily peels off. In addition, since sulfuration and nitridation are performed simultaneously, there is a problem that the diffusion of nitrogen into the surface of the material in the presence of a sulfur compound is reduced, and the nitrided layer becomes thin. Furthermore, due to the demand for dimensional accuracy, low-sulfur type (JP-B-59-6911), in which the amount of sulfur compounds in the molten salt is reduced to a few percent, has become the mainstream. It is necessary to maintain the sulfur concentration and control the oxidation of sulfur and the like, and there are also pollution problems such as waste water treatment of free cyanide due to decomposition of cyanic acid during washing.

Next, the gas method is a method of performing a sulphinitriding treatment in a mixed gas atmosphere of nitrogen, ammonia and hydrogen sulfide. The processing temperature is as high as 500 ° C. or more, and the processing time is as long as 3 hours or more. There is flexibility to control the thickness of the sulfurized layer and the nitrided layer by arbitrarily changing the gas composition in the atmosphere, but it is important to mix the hydrogen sulfide gas and the ammonia gas with heavy specific gravity uniformly. It is important to control the gas pressure, etc., and to design the furnace to maintain the uniformity of the gas composition in the furnace. Further, there is a disadvantage that the processing apparatus becomes expensive, for example, a recovery apparatus for hydrogen sulfide in the exhaust gas is required.

[0008] Subsequently, the ion method is a method in which glow discharge is caused in a mixed gas atmosphere of ammonia and hydrogen sulfide under reduced pressure to perform a sulphonitriding treatment. The processing time is as long as about 4 hours. It has the flexibility to control the thickness of the sulfurized layer and the nitrided layer by arbitrarily changing the gas composition in the atmosphere.However, it is possible to mix hydrogen sulfide gas and ammonia gas with heavy specific gravity uniformly, It is important to control the management and the like and to design a furnace for maintaining the uniformity of the gas composition in the furnace. Further, there is a disadvantage that the processing apparatus becomes expensive, for example, a recovery apparatus for hydrogen sulfide in the exhaust gas is required.

On the other hand, the low-temperature sulfurizing treatment method developed in France in 1964 has a great feature that the surface treatment hardening material such as carburizing and nitriding material can be sulfurized. This method was industrialized in 1970, "Sulfurization treatment by anodic electrolysis of molten salt" (JP-A-59-89693).
Using a molten salt bath containing thiocyanic acid, at a temperature of 170 ° C.
As described above, by performing electrolysis under the conditions of a current density in the range of 1.5 to 4 A / dm ² and a processing time of 4 to 20 minutes, S ²⁻ generated by decomposition of Fe ²⁺ and thiocyanic acid eluted from the article to be processed. Is a treatment method for precipitating iron sulfide on the anode by the reaction with However, although it is a low-temperature sulfurization treatment, since it is a molten salt treatment at 170 ° C or higher, the hardness of the component surface cured by heat treatment decreases, and the base material surface after treatment becomes significantly rough, etc. There's a problem. Furthermore, there is a pollution problem such as waste water treatment of free cyanide due to decomposition of thiocyanic acid during washing.

[0010] Therefore, "Sulfurization treatment of iron or iron alloy"
(Japanese Patent Application Laid-Open No. Hei 11-302897) discloses that one of thiocyanate or thiosulfate of alkali metal or alkaline earth metal is used.
A method has been developed to form an iron sulfide-based film by anodic electrolysis using an aqueous solution in which one or more species are dissolved. Since this method is an aqueous solution treatment, the problem of a decrease in hardness of the heat-treated component has been improved, but it still has pollution problems such as wastewater treatment.

Further, in 1997, a cathodic electrolysis was carried out in an alkaline aqueous solution having a pH of 9 or more, containing a ferric iron ion, a first chelating agent for chelating a ferric iron ion, and a sulfur compound. A method for forming a film having excellent wear resistance and an iron-based material provided with a wear-resistant film (JP-A-11-050297) have been developed. Since this method is an aqueous cathodic electrolysis, it is possible to form a film without a problem of hardness reduction and surface roughness of a heat-treated part.
Because it consists of ferrous ion, sulfur ion and chelating agent,
Wastewater has a feature that can be handled by simple facilities.

The present inventors conducted a quantitative analysis of iron sulfide by X-ray fluorescence (XRF) in order to investigate the content of iron sulfide in the films formed by various nitrosulphurizing treatment methods and electrolytic methods. did.
As a result, it was confirmed that the amount of iron sulfide precipitated in each of the oxynitriding treatments was significantly smaller than that in each of the electrolytic sulfide treatments. From the above, it is considered that the cathodic electrolytic sulfurization treatment method capable of forming a high-purity iron sulfide-based film with simple equipment is a treatment method which has solved the problems of the conventional method. In terms of performance, it has been confirmed that the cathodic electrolytic sulfurization treatment film has an effect of reducing the friction coefficient under sliding conditions under low surface pressure and remarkably improving wear resistance.

[0013]

[Table 1]

The inventors of the present invention have examined the sliding characteristics of the cathodic electrolytic sulfurized film, and found that under severe sliding conditions of high surface pressure, the film cannot exhibit stable performance due to the problem of film adhesion. Was. In general, cathodic electrolytic sulfurization has a large feature not found in conventional methods, considering that sulfurization is applied for the purpose of improving seizure resistance of components used under severe conditions. However, the response to the main demands of the market is inadequate. Further, JP-A-11-30
In 2897, iron ions are added to the electrolyte in a divalent form. The inventors of the present invention conducted additional tests on the anodic electrolytic iron sulfide film, and found that there was room for improvement in the sliding performance because the coefficient of friction was high.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems of the prior art and is intended to provide a stable abrasion resistance and burning resistance under high surface pressure on the surface of a sliding part made of an iron-based material. It is an object of the present invention to provide a processing method for forming a film exhibiting adhesiveness and an iron-based material having such a film.

[0016]

Means for Solving the Problems The present inventors have studied means for solving the above-mentioned problems of the prior art, and as a result, have found that the iron-based material contains trivalent iron ions, a chelating agent and a sulfur-based compound. Anodic electrolysis treatment in an aqueous solution to form an iron sulfide-based film exhibiting stable wear resistance under a high surface pressure on the surface of an iron-based material. It was.

That is, the method for forming an iron sulfide-based film having excellent wear resistance according to the present invention comprises the steps of: subjecting an iron-based material to an anodic electrolysis treatment in an aqueous solution containing a ferric ion, a chelating agent and a sulfur compound. A film substantially composed of iron sulfide is electrolytically deposited on the surface of the substrate. The iron-based material according to the present invention is obtained by subjecting an iron-based material obtained by anodic electrolytic deposition of an iron sulfide-based coating to the surface by performing anodic electrolytic treatment in an aqueous solution containing a trivalent iron ion, a chelating agent, and a sulfur compound. It is characterized in that a coating substantially made of iron sulfide is applied. Hereinafter, the contents of the present invention will be described in detail.

The film substantially composed of iron sulfide formed according to the present invention is formed by combining iron ions eluted from the article to be treated by anodic electrolysis with sulfur ions in the electrolytic solution.
In addition, trivalent iron ions added in advance have an effect of stably forming a film.

The molar concentration of trivalent iron ions in the aqueous solution used in the present invention is preferably in the range of 0.001 to 0.5 mol / L. The pH of the aqueous solution is preferably 8 or more. The molar concentration of the chelating agent is preferably in the range of 0.001 to 2.0 mol / L. The molar concentration of the sulfur compound is preferably in the range of 0.005 to 1.0 mol / L. The electrolysis method includes a constant current electrolysis method, a PR electrolysis method, and a pulse electrolysis method. The treatment temperature of the aqueous solution is preferably in the range of 35 to 60 ° C. Current density in electrolytic treatment is 1 to 20 A / d
in the range of m ² is preferred.

Next, the thickness of the iron sulfide-based coating is preferably 1 to 20 μm. The coating of the present invention can be formed on any conductive material, but industrially important are carbon steels / alloy steels for machine structures, cast irons, iron-based forged products and the like. In particular, it is noted that the present invention is a surface treatment for precipitating an iron sulfide-based coating while softening the hardened surface on a heat-treated material such as carburizing and nitriding and preferably securing a base surface hardness of Hv600 or more. . For heat-treated materials, Fe
Oxide films such as O and Fe ₃ O ₄ are generated and inactivated, so chemical methods such as pickling with hydrochloric acid, sulfuric acid, sulfamic acid and hydrofluoric acid and polishing by electrolytic polishing, and blasting It is preferable to perform a method of removing an oxide film by a physical method such as shot and polishing, and to perform a pretreatment for activation, since the throwing power and adhesion of electrolytic deposition are improved.

[0021]

The aqueous solution composition of the present invention is based on the phenomenon that trivalent iron ions to be a source of iron sulfide generate iron hydroxide "Fe (OH) ₂ and Fe (OH) ₃ " and precipitate. In order to prevent this, a ferric ion is used as a chelating compound with a chelating agent to dissolve and stabilize in an aqueous solution. Figures 1-3
3 is an ESCA chart of Fe, S, and O of an iron sulfide-based film formed on the surface of a steel material by the anodic electrolysis method of the present invention. The horizontal axis is the binding energy, and the vertical axis is the sputtering time. From these figures, peaks of iron sulfide and iron oxide are detected. In addition, another ESCA test showed that Fe and O decreased from the surface of the film to the inside, but S was strongly detected. From these results, it was confirmed that the iron sulfide-based coating of the present invention was substantially composed of iron sulfide, and was a coating containing a small amount of iron oxide.

[0022]

A preferred embodiment of the present invention is that the chelating agent is an important component which also affects the adhesion and uniformity of the film. Representative examples are shown below. (a) Aliphatic carboxylic acids such as citric acid, gluconic acid, tartaric acid, etc. Acid type (c) Aromatic type such as 5-sulfosalicylic acid, pyrocatechol-3,5-disulfonate, sulfonic acid, etc. (e) 8-oxyquinoline, oxine-5-sulfonic acid,
Oxynones such as 7-iodooxin-5-sulfonic acid (f) Aromatic compounds having an amino group m-aminophenol, 3-aminobenzenesulfonic acid 3-amino-4-hydroxybenzenesulfonic acid 3-amino- 4-methoxybenzenesulfonic acid 4-amino-3-methylbenzenesulfonic acid aminophenol disulfonic acid 1-amino-2-naphthol-4-sulfonic acid 4-amino-3-hydroxy-1-naphtholsulfonic acid (g) nitro Aromatic system having a group 3-nitrobenzenesulfonic acid nitrophenolsulfonic acid nitrothiophenol 6-nitro-2-aminophenol-4-sulfonic acid nitronaphthalenesulfonic acid 4,4'-dinitrostilbene-2,2'-disulfonic acid (h) Carboxylic acids having an amino group Aminosalicyl nophthalate, 5-Amino-2-hydroxybenzoic acid 2-Aminothiazole-4-carboxylic acid 2-Amino-3-pyridinecarboxylic acid (i) Carboxylic acid having a nitro group 3-5-Dinitrobenzoic acid 2 -Hydroxy-3,5-dinitrobenzoic acid Nitrophthalic acid Nitroterephthalic acid α-Nitropropionic acid (j) Alcohol system having amino group Aminoquilnadine (k) Alcohol having nitro group Nitro-1-naphthylamine Nitro-1-naphthol Nitrohydroquinone 4-Nitrotoluene-2-sulfonic acid Nitrophenylacetic acid Nitro-1-naphthoic acid (l) Other diethylenetriamine Acetate Metro mercapto ethylene imino amino diacetic acid diethylene triamine penta (methylene sulfonic acid) 8-hydroxy-5-nitropyridine-nitro -m- tolidine

Next, typical examples of the substance serving as a source of sulfur for forming iron sulfide are described below. Sulfides such as potassium sulfide, sodium sulfide, and ammonium sulfideSulfates such as potassium thiosulfate, sodium thiosulfate, and ammonium thiosulfate Sulfur compounds such as potassium, sodium tetrathiosulfate, ammonium tetrathiosulfate, etc. It is desirable to be in the range of 1.0 mol / L.

Next, the reasons for limiting the preferable electrolysis conditions will be described. First, the molar concentration of trivalent iron ions is 0.001mol / L
If it is less than 3, the reaction occurs mainly on iron eluted from the article to be treated, because the iron source required for iron sulfide formation is insufficient. As a result, the surface roughness and dimensional change of the article to be processed become a problem. On the other hand, the molar concentration of trivalent iron ions is 0.5 mol.
If / L is exceeded, iron hydroxide or iron sulfide precipitates as a precipitate in the aqueous solution, which is not suitable for bath management. Therefore, the molar concentration of trivalent iron ions is preferably in the range of 0.001 to 0.50 mol / L.

Next, when the molar concentration of sulfide, thiosulfate and dithionite sulfate is less than 0.005 mol / L, precipitation of iron sulfide becomes difficult even if the treatment is carried out for a long time under good electrolytic conditions. Become. On the other hand, when the molar concentration of the sulfide or the like exceeds 1.0 mol / L, a precipitate is excessively formed, which poses a problem in management. Therefore, the molar concentrations of sulfide, thiosulfate and dithionite are preferably in the range of 0.01 to 0.8 mol / L.
The molar concentration of tetrathione sulfate is preferably in the range of 0.005 to 0.4 mol / L.

On the other hand, the pH of the aqueous solution was regulated to 8 or more.
If H is less than 8, iron sulfide does not precipitate in accordance with the current density and time, and it is difficult to control the film. Also,
In order to maintain the pH at 13 or more, an alkali such as potassium hydroxide or sodium hydroxide must be frequently added to the electrolytic bath. In order to perform simple film control and bath management at low cost, the PH control range is preferably 10.0 to 12.0.

In the present invention, the long-term treatment by constant current electrolysis is performed by using pulse electrolysis when the film formation is stopped due to the transition to the oxidized region (passivation). Is preferred. Further, by using the PR electrolysis method in which anodic electrolysis and cathodic electrolysis are used in combination, it is possible to form a cathodic electrolytic film exhibiting conformability on the outermost surface and a seizure-resistant anodic electrolytic film on the second layer.

Next, when the processing temperature is lower than 35 ° C., iron sulfide hardly precipitates even under the optimal electrolytic conditions, and it becomes difficult to form a uniform film on the article to be processed. Processing temperature
When the temperature exceeds 60 ° C., precipitation of iron sulfide is possible, but a reduction in bath life due to decomposition of the chelate compound poses a problem. Therefore, the treatment temperature is preferably in the range of 30 ° C. to 60 ° C.

Under the electrolysis conditions where the anode current density is less than 1 A / dm ² , the elution of iron from the article to be treated is not uniform, so that spots are formed on the formed film. The anode current density is 20 A /
If it exceeds dm ² , the transition from the elution reaction of iron to the oxidation reaction will inactivate the surface of the article to be treated, making it difficult to form a film. Therefore, the current density is preferably in the range of 1 to 20 A / dm ² .

Therefore, when the above-mentioned components of the aqueous solution composition are set in the preferable ranges, it is possible to control and form a 1 to 20 μm iron sulfide film by an arbitrary combination of current density, processing time and processing time. Became.

Further, potassium sulfite and sulfite are added to the above aqueous solution.
Sulfites such as sodium sulfate and ammonium sulfite
Addition of K precipitates during electrolysis_TwoS_X, Na_TwoS_X,
(NH _Four)_TwoS_XPolysulfides such as
Can be kept constant inside.

Since the method of the present invention belongs to the electrolysis method, it is not easy to appropriately adopt general common sense of the electrolysis method. For example, 0.5 mol / L or more of highly soluble salts such as potassium, sodium, and ammonium sulfates, hydrochlorides, pyrophosphates, and amidesulfonates serving as electrolytes are added to all the aqueous solutions described above, and the current density is increased. It is common general knowledge of plating to make the polarization curve of voltage and voltage horizontal, and to uniformly reverse the current density on the material to be processed to achieve uniformity of the sulfide layer, so that it is naturally applicable to the present invention. is there.

[0033]

[Example] [Example 1] SRV test piece (φ
(27 mm x 7.9 mm) was used as a test material and subjected to sulfuration treatment. FIG. 4 shows a series of processing steps. Oil and dust attached to the heat-treated parts such as carburizing and nitriding are removed with an alkaline degreasing agent and washed with water. Next, the oxide film on the outermost surface is removed by a chemical method, washing and neutralization are performed, and after performing a pretreatment of removing the oxide film by a physical method, degreasing and washing for removing abrasives are performed. Do. The sulfuration treatment is performed by using the electrolytic deposition apparatus shown in FIG.
Electrolysis is carried out at a treatment temperature of 40 ° C. and PH10 for 15 minutes at 5 A / dm ² in an aqueous solution containing 420 parts by weight of a chelating agent and 20 parts by weight of a sulfur compound per 0 parts by weight.
At this time, an iron sulfide-based film having a thickness of 14 to 15 μm was formed on the SUJ2 SRV test piece. FIG. 6 shows a cross-sectional photograph of the film. The post-treatment was performed by hot-air drying at 80 to 100 ° C. after washing with water or hot water, and applying oil for the purpose of rust prevention.

Example 2 Example 1 was conducted in an aqueous solution (420 parts by weight in total) containing 120 parts by weight of a chelating agent and 80 parts by weight of a sulfur compound with respect to 100 parts by weight of ferric ion.
The thickness is 15 to 16μ by electrolyzing according to the method described in
m of iron sulfide-based film was formed.

Example 3 60000 parts by weight of a chelating agent and 400 parts of a sulfur compound per 100 parts by weight of ferric ion
By electrolyzing in an aqueous solution containing 0 parts by weight by the method described in Example 1, an iron sulfide-based film having a thickness of 3 to 5 μm was formed.

Example 4 The thickness of the electrolyte was determined by electrolysis in an aqueous solution containing 0.5 parts by weight of a chelating agent and 20 parts by weight of a sulfur compound with respect to 100 parts by weight of trivalent iron ions according to the method described in Example 1. Formed an iron sulfide coating having a thickness of 10 to 12 μm.

Example 5 The thickness of the electrolyte was adjusted by electrolysis in an aqueous solution containing 1000 parts by weight of a chelating agent and 20 parts by weight of a sulfur compound with respect to 100 parts by weight of trivalent iron ions according to the method described in Example 1. Formed an iron sulfide coating having a thickness of 14 to 15 μm.

Example 6 The thickness of the electrolyte was determined by electrolysis in an aqueous solution containing 300 parts by weight of a chelating agent and 2.5 parts by weight of a sulfur compound with respect to 100 parts by weight of trivalent iron ions according to the method described in Example 1. Of 1 to 2 μm was formed.

Example 7 The thickness of the electrolyte was adjusted by electrolysis in an aqueous solution containing 300 parts by weight of a chelating agent and 5000 parts by weight of a sulfur compound with respect to 100 parts by weight of trivalent iron ions according to the method described in Example 1. Of 18 to 19 μm was formed.

Example 8 An electrosulfide film having a thickness of 4 to 5 μm was formed by electrolysis for 5 minutes according to the method of Example 1.

Example 9 When the pH of the aqueous solution was changed to 11.5 and electrolysis was performed by the method of Example 1, the thickness was 15 to 16
A μm iron sulfide-based film was formed.

Example 10 The treatment temperature was changed to 50 ° C., and electrolysis was performed for 5 minutes by the method of Example 1.
m of iron sulfide-based film was formed.

[0043]

[Table 2]

The anti-seizure performance of the iron sulfide coating formed in Example 1 was confirmed using an SRV tester. As shown in FIG. 6, the SRV test is sliding at a point contact between the disk and the ball. The surface pressure is very high, and a sliding test under severe conditions can be performed.
The test conditions and test results are described below. In addition, an untreated test was also performed as Comparative Example 1. As a result, the effect of improving the anti-seizure performance by more than three times by the electrolytic deposition of the iron sulfide-based coating according to the present invention has been clarified.

[0045]

【Test condition】

 Step load: 50N / min Vibration frequency: 50Hz Sliding distance: 2mm Counterpart material: φ1.0 (SUJ2) Oil used: spindle oil (No. 2)

[0046]

[Table 3]

The sliding performance (friction coefficient) of the iron sulfide-based coating formed in Example 1 was confirmed using the SRV tester shown in FIG. The test conditions are shown below. The films formed by the conventional method were also evaluated in Comparative Examples 2 to 5. As a result, the iron sulfide-based film electrolytically deposited according to the present invention has a friction coefficient reduced to about one half compared with the conventional method,
The effect of dramatically improving the sliding performance was clarified.

[0048]

【Test condition】

 Load: 250N Frequency: 50Hz Sliding distance: 2mm Mating material: φ1.0 (SUJ2) Oil used: Grease (molybdenum disulfide added)

[0049]

[Table 4]

[0050]

According to the present invention, an iron sulfide-based film can be electrolytically deposited in an alkaline aqueous solution at a temperature of 60 ° C. or less. The problem of reduced surface hardness of heat treated parts, which was a problem in 1984-8973), has been resolved. In addition, various sulfurizing treatment methods are mainly applied to sliding parts of automobiles and motorcycles. Recently, however, there is a strong demand for low fuel consumption in the market, and there is a movement to reduce the weight and improve the fuel economy. For this reason, sliding parts have been miniaturized, and the use conditions have become more severe at higher surface pressures. The iron sulfide-based film electrolytically deposited according to the present invention has abrasion resistance performance far exceeding the conventional method, and it is possible to provide a technique adapted to future market needs.

[Brief description of the drawings]

FIG. 1 is an ESCA chart showing the binding energy of Fe of a film formed according to the present invention.

FIG. 2 is an ESCA chart showing the binding energy of S of a film formed according to the present invention.

FIG. 3 is an ESCA chart showing the binding energy of O of a film formed according to the present invention.

FIG. 4 is a flowchart illustrating an electrolytic deposition apparatus according to the present invention.

FIG. 5 is a schematic view of an electrolytic deposition apparatus for carrying out the method of the present invention.

FIG. 6 is an iron sulfide-based film formed under the conditions of Example 1.

FIG. 7 is an image diagram of the SRV test machine implemented in Example 1.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hidemasa Sato 1-15-1 Nihonbashi, Chuo-ku, Tokyo Japan F-term in Parkerizing Co., Ltd. 4K044 AA02 AB05 BA18 BA19 BB03 BC01 CA12 CA17 CA18

Claims (12)

[Claims] 1. A film substantially composed of iron sulfide is electrolytically deposited on the surface of an iron-based material by subjecting the iron-based material to anodic electrolysis in an aqueous solution containing a ferric ion, a chelating agent, and a sulfur compound. A method for forming an iron sulfide-based film having excellent sliding properties. 2. The method according to claim 1, wherein the chelating agent in the aqueous solution has a molar concentration of 0.001 to 2.0 mol / L. 3. The method according to claim 1, wherein the molar concentration of the sulfur compound in the liquid is 0.00
3. The method for forming an iron sulfide-based film having excellent slidability according to claim 1, wherein the iron sulfide-based coating is in a range of 5 to 1.0 mol / L. 4. The iron sulfide excellent in slidability according to any one of claims 1 to 3, wherein the ferric iron ions in the aqueous solution have a molar concentration in a range of 0.001 to 0.5 mol / L. How to form a system film. 5. The method according to claim 1, wherein the anodic electrolysis is performed by a constant current method or a pulse electrolysis method. 6. The method according to claim 1, wherein the anodic electrolysis is performed by a PR electrolysis method, and the cathodic electrolysis of the PR electrolysis is performed in an aqueous solution containing a ferric ion, a chelating agent, and a sulfur compound. 3. The method for forming an iron sulfide-based film having excellent slidability according to item 1. 7. The method for forming an iron sulfide-based coating having excellent slidability according to claim 1, wherein a treatment temperature of the aqueous solution is in a range of 35 to 60 ° C. 8. The method according to claim 1, wherein the anode current density is in the range of 1 to 20 A / dm ² . 9. An iron-based material obtained by anodic deposition of an iron sulfide-based film on the surface is subjected to anodic electrolysis in an aqueous solution containing trivalent iron ions, a chelating agent and a sulfur compound. An iron-based material having a coating substantially made of iron sulfide. 10. The iron-based material according to claim 9, wherein the base of the coating is a steel material whose surface is hardened to Hv600 or more by carburizing, nitriding, or induction hardening. 11. The iron-based material according to claim 9, wherein said coating has a thickness of 1 to 20 μm. 12. The film according to claim 9, wherein another film formed by performing cathodic electrolysis in an aqueous solution containing ferric ion, a chelating agent and a sulfur compound is applied to the surface of the film. 12. The iron-based material according to any one of items 11 to 11.