JP3249059B2 - Surface treatment liquid for metal sliding member and surface treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment liquid for a metal sliding part material used in transportation machines such as automobiles and ships, and general industrial machines and the like, and a surface treatment method using the same. According to the present invention,
The present invention relates to a surface treatment liquid for a metal sliding member useful as an engine part and the like, and a surface treatment method using the same.

[0002]

2. Description of the Related Art Metal sliding members used in engines and the like,
For example, a plain bearing is generally manufactured by processing a bimetal in which a sliding alloy is bonded to an iron, stainless steel, or aluminum alloy backing metal into a cylindrical bushing or a half-split shape.

As alloys for metal sliding members, copper-lead alloys and aluminum alloys are mainly used. In order to improve conformability, fatigue resistance and abrasion resistance, Sn and Sn are further added. It was necessary to form an overlay layer by electroplating a soft metal or alloy such as Pb to a thickness of about 5 to 30 μm.

As an aluminum alloy used as an alloy for a sliding member requiring such an overlay plating layer, for example, JIS H5402 AJ-1 (10%
Sn-0.75Cu-0.5Ni-Al Bal) and JIS H5402 AJ-2 (6% Sn-2.5
Cu-1.0Ni-Al Bal) and the like, and as a copper-based alloy, JIS H5403 KJ3 (70% Cu-
30% Pb-Sn) and KJ4 (76% Cu-24).
% Pb-Sn).

However, even in a sliding member having a soft metal overlay plating layer formed on these sliding member alloys, the heat resistance and wear resistance of the overlay plating layer are low and the lubricating oil is used under high load conditions. Since the temperature of the lubricating surface rises due to the temperature rise, fatigue and seizure phenomena occur in the sliding member, and the sliding member may become unusable.

In addition, in the case of the sliding member with an overlay plating layer, there are also problems that many steps are required for processing, such as the need for electroplating after machining, resulting in a decrease in productivity and an increase in cost.

[0007] On the other hand, it is known to apply a chemical conversion coating having excellent heat resistance to the surface of a sliding member, for example, a plain bearing. For example, European Patent EP-PS 0059273.
And JP-A-64-49713 disclose a synthetic plain bearing.

In the invention of the above-mentioned European Patent, an aluminum alloy bearing is treated with a zinc phosphate-based solution to form a zinc phosphate crystal film on the bearing alloy, and a uniform concentrated load is applied to the bearing surface except for localized concentrated loads. A load of distribution is applied to improve the conformability. The invention of the publication also improves this and prevents the formation of a zinc phosphate film on the outer peripheral surface of the bearing, thereby fixing the disadvantage of the invention of the European patent, namely, fixing the bearing to the bearing housing. This is to prevent loosening that occurs when doing so.

Japanese Patent Application Laid-Open (JP-A) No. 57-186620 discloses a method of subjecting a copper alloy bearing to a chemical conversion treatment by immersing it in a ferric chloride solution to form a copper chloride film.

However, even in the aluminum alloy bearing coated with the zinc phosphate film described above, zinc phosphate forms crystals having a particle size of about several μm to several tens μm, and is therefore sufficiently smooth. No surface was obtained. For this reason, the frictional resistance during sliding is large, and there is a problem in seizure resistance and abrasion resistance under a high load.

On the other hand, in a copper alloy bearing, a method is also known in which a bearing base material is immersed in a ferric chloride solution to form a copper chloride film on the surface thereof. Dicopper was not satisfactory because it was crystalline, water-soluble and unstable as before.

In addition, unlike a general alloy material, a bearing alloy is formed by alloying a soft metal such as tin or lead with a fixed component ratio to a base metal such as aluminum or copper, and further requires Si, Ni and the like. It has a special composition that is included accordingly.

[0013] For this reason, it is difficult to form a good film on the bearing alloy by the conventional surface treatment liquid which has been used for applications such as rust prevention and coloring. Particularly, aluminum alloys and copper alloys (Kelmet ), There has been no chemical conversion solution usable before.

That is, a surface treatment film and a surface treatment method for imparting excellent seizure resistance and wear resistance to an aluminum alloy or copper alloy sliding member have not been found yet.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems of the prior art, and is intended for a sliding member base such as an aluminum alloy and a copper alloy.
It is possible to form a film easily and inexpensively by chemical conversion treatment without applying overlay plating.
An object of the present invention is to provide a surface treatment liquid for producing a sliding member having excellent lubricity and wear resistance, and a surface treatment method using the same.

[0016]

SUMMARY OF THE INVENTION The present inventors have developed an anti-seizure and abrasion-resistant aluminum alloy or copper alloy sliding member which has conventionally required overlay plating without plating. To improve
First, a chemical conversion treatment solution having various compositions to be applied to the surface of an aluminum alloy sliding member was prepared, and the sliding performance of a treated film formed thereby was studied diligently.

As a result, when a conventionally known crystalline compound film such as zinc phosphate, sodium aluminum fluoride and manganese phosphate is formed on the surface of the aluminum alloy sliding member, the surface of the sliding member becomes crystalline. It is covered with polycrystalline particles having a diameter of 2 to 4 μm, thereby losing the smoothness of the sliding member surface and increasing the friction coefficient (μ) of the film. It came to the conclusion that it was easy to do.

Further, even if the film has a smooth surface, if the adhesion of the film after drying is insufficient, it is also confirmed that a problem occurs in the wear resistance and seizure resistance of the sliding surface. did.

Based on these findings, the present inventors have found that amorphous,
Alternatively, further research was conducted on the composition and coating composition of a chemical conversion treatment solution that is useful for obtaining a chemical conversion coating that is a low-crystalline coating with excellent smoothness and abrasion resistance, as well as excellent adhesion and heat resistance. Was.

As a result, the aluminum alloy sliding member is
By treating the sliding member with an aqueous solution containing chromium group ions selected from molybdate ions, tungstate ions, chromate ions, and the like, and phosphate ions and fluoride ions, the sliding member is provided with a chromium group metal oxide (or water). A composite film of hydrated oxide and phosphate is formed.
Good adhesion, smoothness, and heat resistance to sliding members such as aluminum alloys, as well as abrasion resistance,
It has been found that it has excellent seizure resistance.

However, when the above-mentioned treatment liquid is applied to an aluminum alloy, aluminum ions eluted and accumulated in the treatment liquid with the progress of the treatment react with fluoride ions and alkali metal ions to form crystalline fluorine. Because the compound is eutectoid, the sliding performance fluctuates and it is difficult to stabilize it.When this is applied to a copper alloy-based sliding member, the copper alloy surface is passivated to form a chemical conversion film. However, there was a problem that sufficient performance could not be obtained. The present inventors cause such a problem because the potential of the copper alloy in the processing solution is more noble than the reduction precipitation potential of the chromium group metal ion, so that the chemical conversion reaction does not proceed, and the complex of the eluted ions. Is not formed. In addition, we have found that thiourea,
By coexisting a sulfur compound selected from thiosulfate and thiocyanate with chromium group ions such as molybdate ion, tungstate ion and chromate ion in the treatment liquid, aluminum alloy can be used for copper alloy. It was newly found that the chemical conversion film forming reaction can be advanced in the same manner as described above, and that a stable chemical conversion treatment can be performed even in the presence of fluoride ions, and that excellent sliding performance can be obtained. .

Further, the present inventors improve the adhesion, abrasion resistance, and seizure resistance of the resulting chemical conversion film to the sliding member base alloy by causing the presence of phosphate ions in the treatment liquid. The present inventors have found that the addition of fluoride ions to such a treatment solution is effective in improving the chemical conversion reactivity, and completed the present invention.

That is, the surface treatment solution for a sliding member of the present invention comprises at least one selected from thiourea, thiosulfate, and thiocyanate, molybdate ion, tungstate ion, and chromate ion. And at least one selected from the group consisting of: Preferably, the treatment liquid composition further contains a phosphate ion. Further, it is preferable that the treatment liquid further contains fluoride ions.

Further, in the surface treatment method for a sliding member according to the present invention, the surface of the metal sliding member or the metal material for the metal sliding member is brought into contact with the surface treatment liquid of the present invention or the surface treatment liquid of the present invention. In a surface treatment liquid, a chemical conversion film is formed on the surface of the sliding member by subjecting the surface of the sliding member to electrolytic treatment.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The surface treatment liquid for metal sliding members of the present invention contains at least one sulfur compound selected from thiourea, thiosulfate and thiocyanate,
It contains at least one selected from molybdate ions, tungstate ions, and chromate ions. Among thioureas, thiosulfates, and thiocyanates, thioureas have an advantage that they have good stability even at a high processing solution temperature. The source of the thiosulfate or thiocyanate is not limited, but is preferably selected from thiosulfate or an alkali metal or ammonium thiocyanate. In the surface treatment liquid of the present invention, the concentration of these sulfur compounds is not particularly limited, but the total concentration is preferably from 0.3 to 50 g / l, more preferably from 1 to 10 g / l. If the sulfur compound concentration is less than 0.3 g / liter, a predetermined film may not be easily formed, and if it exceeds 50 g / liter, precipitation may easily occur.

The pH of the surface treatment solution of the present invention is preferably 3-7. If the pH is less than 3, the sulfur compound may be easily decomposed, and if it is more than 7, a film may not be easily formed.

Of the chromium group metal compound ions selected from molybdate ions, tungstate ions and chromate ions contained in the surface treatment solution of the present invention, molybdate ions are most preferable, and then tungstate ions are preferable. The source of the chromium group metal acid ion is not particularly limited, but it is preferable to use an ammonium salt and an alkali metal salt of a chromium group metal compound such as ammonium molybdate. It is more preferable to use.
The concentration of these chromium group compound ions is not particularly limited, but the total concentration is preferably from 0.2 to 50 g / l, more preferably from 1 to 30 g / l. In the surface treatment liquid of the present invention, the weight ratio of the total amount of the sulfur compound ions to the total amount of the chromium group metal compound ions is 0.3 to 50: 0.2 to 50.
And more preferably 1 to 10: 1 to 30.

In the surface treatment solution of the present invention, it is preferable that the composition further contains a phosphate ion. The source of the phosphate ions is not particularly limited, but it is preferable to use monosodium phosphate, monoammonium phosphate, and monopotassium phosphate. The phosphate ion concentration in the surface treatment solution of the present invention is not particularly limited, but is preferably 2 to 150 g / liter, and more preferably 10 to 80 g / liter. Even when phosphoric acid is added, the types and concentrations of the sulfur compound and the chromium group metal compound ions are the same as described above.

The surface treating solution of the present invention may further contain fluoride ions in addition to the surface treating solution composition. The types of fluoride ions is not particularly limited, fluorine ion (F ^-) is preferable to use, silicic fluoride ions (SiF ₆ ^2-like), boron fluoride ions (BF ₄ ^-
Etc.) can also be used. When fluoride ions (F ⁻ ) are used, sodium fluoride, sodium acid fluoride, hydrofluoric acid and the like can be used. The concentration of fluoride ions in such a surface treatment solution was converted to F. If 0.2
It is preferably from 5 to 5 g / liter, whereby the chemical conversion reactivity of the surface treatment solution of the present invention with respect to the aluminum alloy can be further improved. When phosphate ions and fluoride ions are contained in the surface treatment solution of the present invention, the addition amount of phosphate ions and fluoride ions is 2 to 50 parts by weight of the chromium group metal compound and 2 parts by weight of phosphate ions.
It is preferable that the amount be from 150 to 150 parts by weight and from 0.5 to 5 parts by weight of fluoride ions.

Next, the surface treatment method for a sliding member of the present invention will be described. First, in one embodiment, the surface of a metal sliding member, for example, a slide bearing after bending into a half-cylindrical shape, or a bimetal for a sliding bearing before processing, or a metal material for a sliding member, The chemical conversion film is formed on the surface of the sliding member by contacting the surface treatment liquid. The method of contacting the surface treatment liquid with the surface of the sliding member is not particularly limited. For example, it is preferable that both are contacted at a liquid temperature of 40 to 90 ° C. for 30 to 300 seconds. If the treatment temperature is lower than 40 ° C., a long time is required for the treatment, and if it exceeds 90 ° C., the decomposition of the sulfur compound is promoted and the aging of the solution may be accelerated. Further, it is preferable that the surface treatment liquid is brought into contact with the surface of the sliding member by an immersion method, a spray method, a pouring method, or the like. For a sliding material treated under such conditions, for example, a bearing or a bimetal for a bearing, a thickness of 0.
A chemical conversion film having a thickness of 2 to 5 μm is formed, and when the sliding member backing is steel, the thickness of the backing metal surface (back surface) is 0.1 to 0.1 μm.
An amorphous thin film of 1 μm is formed, which exhibits an effect as a rust-preventive film, and at the same time, has an effect of preventing seizure between the bearing and the bearing housing. If the thickness of the chemical conversion film formed on the sliding member is less than 0.2 μm, the sliding performance may be insufficient, and if it exceeds 5 μm,
The surface roughness becomes excessive and the amount of wear increases.

In another embodiment of the surface treatment method according to the present invention, a sliding member, for example, a bearing or a bimetal for a bearing or a metal material for a metal sliding member is used as a cathode or an anode, and an insoluble electrode is used as a counter electrode. Then, in the surface treatment liquid of the present invention, electrolysis is performed on the surface of the sliding member or the metal material. In this case, it is more preferable to use a sliding member, for example, a bearing or a bimetal for the bearing as the cathode. Platinum-plated titanium electrodes and DS
It is preferable to use E (Dimensionally Stable Electrode). The electrolysis operation is performed at a current density of 0.2 to 5 A /
It is preferably applied in dm ² 10 to 300 seconds. The thickness of the resulting chemical conversion film is preferably from 0.2 to 5 μm, more preferably from 0.5 to 2 μm. When the electrolytic conversion coating is less than 0.2 μm, the obtained sliding performance may be insufficient, and when it exceeds 5 μm,
There is a disadvantage that the adhesion of the film is reduced and the film is easily worn.

The thiourea, thiosulfate, and / or thiocyanate contained in the sliding member surface treatment liquid of the present invention is characterized in that the sulfur atoms in these compounds are converted to copper or copper in the sliding member alloy. Coordination with metal atoms such as aluminum to form a complex compound, thereby shifting the corrosion potential of metals such as copper to the base side, eluting metal atoms on the surface of the alloy substrate as ions, and at the same time, molybdate ions Has the effect of enabling the reduction precipitation of chromium group metal compound ions.

For this reason, when the surface treatment liquid of the present invention is brought into contact with a sliding member, for example, a sliding bearing or a bimetal for a sliding bearing, to form a surface treatment film, aluminum or copper on the surface of the sliding member alloy is used. Atoms are ionized,
The electrons generated at that time are hexavalent Mo (VI), W (V
It is thought that I) or Cr (VI) ions are reduced and these are deposited as an amorphous film mainly composed of insoluble trivalent, tetravalent or pentavalent metal oxides or hydrated oxides. Can be The chemical conversion film thus formed becomes a film mainly composed of an oxide by drying. Such a chemical conversion film is smooth and has good adhesion and abrasion resistance, and can improve the sliding performance of the sliding member.

When the surface treatment liquid of the present invention containing phosphate ions is brought into contact with a sliding member, for example, a slide bearing or a bimetal for a slide bearing, to form a surface treatment film, aluminum or copper is formed in the same manner as the former. The atoms are ionized, and the electrons generated at that time are hexavalent Mo (VI), W
(VI) or Cr (VI) ions are reduced to deposit them as an amorphous film mainly composed of insoluble trivalent, tetravalent or pentavalent metal oxides or hydrated oxides. At this time, since the reduction reaction of the chromium group metal compound ion involves the consumption of H ⁺ ions, the pH near the interface between the sliding member and the surface treatment solution rises, and the metal phosphate eluted in the surface treatment solution It is thought that the eluted metal phosphate co-eutects with the chromium group metal oxide (hydrated oxide) to form a composite film of these because the pH exceeds the precipitation equilibrium pH. This chromium group metal oxide-phosphate amorphous composite film has better smoothness and adhesiveness than the film composed of each of the chromium group metal oxide and phosphate, and has a better sliding member surface. It has excellent properties as an overlay film.

When the surface treatment liquid of the present invention further contains fluoride ions, a chemical conversion film is formed by the same reaction as described above, but the fluoride ions prevent the passivation of the sliding member base metal material, It has the effect of improving the film formation rate and preventing partial defects of the film. When fluoride ions are contained in the surface treatment solution of the present invention, the metal eluted in the surface treatment solution forms a crystalline fluorine compound such as sodium aluminum fluoride, which is precipitated as an impurity in the chemical conversion film. However, the surface treatment solution of the present invention and the sulfur compound such as thiourea contained therein also have the effect of preventing the precipitation of these impurities and stabilizing the film performance.

Further, in the embodiment in which the film is formed by an electrolytic reaction in the surface treatment method of the present invention, a sliding member, for example, a bearing is used as an anode or a cathode, an insoluble electrode is used as a counter electrode, and This is for performing electrolysis. When a sliding member, for example, a bearing or a bearing bimetal is used as the anode, aluminum and copper in the sliding member base alloy are eluted, and these eluted ions immediately react with phosphate ions and precipitate to form a film. Thought to form,
At this time, a sulfur compound such as thiourea is effective for dissolving a uniform film and forming a dense film. When a sliding member, for example, a bearing or a bearing bimetal is used as a cathode, chromium group metal compound ions are reduced and precipitated,
Simultaneously increasing the interfacial pH forms an amorphous composite film composed of a chromium group metal oxide-phosphate mixture. Therefore, this method has an advantage that the thickness of the obtained film can be arbitrarily controlled.

The chemical conversion film obtained by the method of the present invention has a very smooth surface since it has excellent adhesion to the surface of the sliding member base material and has almost no crystallinity. For this reason, the frictional resistance between the sliding member covered with the chemical conversion film and the mating material is extremely small, and when the sliding member contains phosphate, the phosphate is a solid lubricant and is subjected to extreme pressure addition. Since it also acts as an agent, the seizure resistance and wear resistance of the sliding member are significantly improved. The chemical conversion film obtained by the method of the present invention may have fine microcracks in some cases, but such cracks can be expected to exhibit an effect as an oil reservoir.

The sliding member used in the method of the present invention includes a bearing material, an engine piston material, a valve lifter material, an A / T valve spool material, a piston ring material, a cylinder bore material, a cylinder head material, and a power transmission system joining member. Aluminum alloys (Al—Sn alloy, Al—Mg alloy, Al
-Si alloy, etc.) and copper alloy (Cn-Pb alloy, Cn
-Sn alloy etc.).

[0039]

The present invention will now be described in detail with reference to several examples and comparative examples.

In Examples and Comparative Examples, (A) As a test material, an aluminum alloy for bearing (Al-
6% Sn-1% Cu-Ni) sheet is roll-bonded by a roll rolling method and then annealed, and (B) a copper alloy for bearing (Kelmet: 76% Cu-24% Pb-Sn) is rolled. After rolling and joining by a rolling method, two types of bearing bimetals which were annealed and bearing materials using these materials were used. Next, cut the obtained bimetal,
A bearing test piece was prepared by machining.

The test metal material was concentrated at a concentration of 20 g / liter and 70 g using an alkaline degreasing agent (registered trademark: Fine Cleaner 315: manufactured by Nippon Parkerizing Co., Ltd.).
After degreased at 2 ° C. for 2 minutes and washed with water, this was subjected to a film forming treatment, further washed with water, and dried with hot air at 120 ° C. for 5 minutes.

Tables 1 and 2 show the compositions of the surface treating agents.
Tables 3 and 4 show the types of the test materials, the surface treatment conditions, the amount of coating film, and the surface roughness (Rz). The materials used in the tests were aluminum alloy (A) in Examples 1 to 6, Examples 12 and 13, and Comparative Examples 1 and 3, and Examples 7 to
11, Examples 14, 15 and Comparative Example 4, used a copper alloy (B).

In Examples 12, 14 and Comparative Example 3, films were formed by electrolytic treatment using a bearing as a cathode and a platinum-plated titanium plate as an anode.
5 and Comparative Example 4 were electrolyzed using the bearing as an anode. The current density was set at 0.8 A / dm ² . Examples 5 and 10
Was brought into contact with the treatment liquid by a spray method, and all other Examples and Comparative Examples were brought into contact with the treatment liquid by an immersion method to form a surface treatment film on the bearing alloy. Processing is at liquid temperature 7
Performed at 5 ° C. for 240 seconds.

The molybdate ion in the treatment liquid is ammonium molybdate, the tungstate ion is sodium tungstate, the chromate ion is ammonium bichromate, and the fluoride ion is sodium fluoride or ammonium fluoride. It was added so that the concentration became the value in the table. The thiosulfate and thiocyanate were all sodium salts.

The phosphate ions were added as monosodium phosphate. The pH of the solution was all in the range of 4 to 7.

The thickness of the surface-treated coating layer was measured on a scale using a metallographic microscope after the treated bearing was cut, embedded in an embedded resin, and mirror-polished in cross section.

The surface roughness of the film surface was measured by Rz using a surface roughness meter (Surfcom 470, manufactured by Tokyo Seimitsu Co., Ltd.).

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

The bearing test pieces after the treatment were subjected to a seizure test and a wear test using a rotary load tester. The conditions of the seizure test and the abrasion test are shown below, and the test results are shown in FIGS. 1 and 2.

[Seizure test conditions] Test apparatus: Static load bearing tester Revolution: 5000 rpm Lubrication amount: 0.1 liter / min Circumferential speed: 12.5 m / sec Lubricating oil: SAE 10W-30 Lubricating temperature: 100 ± 2 ° C Shaft material: S50C (quenched, surface roughness Rz: 0.8 μm) Judgment method: When bearing back surface temperature rises sharply or when motor overloads

[Abrasion test conditions] Test apparatus: Static load bearing tester Revolution: 5000 rpm Oil supply amount: 0.1 liter / min Circumferential speed: 12.5 m / sec Lubricating oil: SAE 10W-30 Surface pressure: 50 MPa Shaft material : S50C (quenching, test time: 10Hr, surface roughness Rz: 0.8 μm)

[0055]

As is clear from the results shown in Tables 1 and 2 and FIGS. 1 and 2, Examples 1 to 1 using the surface treatment liquid of the present invention were used.
The sliding member obtained in 5 had excellent seizure resistance and abrasion resistance. On the other hand, the sliding members of Comparative Examples 1 to 4 using surface treatment liquids outside the range of the present invention were inferior in both seizure resistance and abrasion resistance. By performing a surface treatment on the aluminum alloy sliding member or the copper alloy sliding member by the surface treatment liquid and the surface treatment method for a metal sliding member of the present invention,
It is clear that a surface treatment film is formed on the surface of these metal sliding members, which can significantly improve the seizure resistance and wear resistance of the sliding members, and are used for a wide range of applications such as automobile engines. In the production of, its practical effect is great.

[Brief description of the drawings]

FIG. 1 is a graph showing seizure test results of sliding members of Examples 1 to 15 and Comparative Examples 1 to 4.

FIG. 2 is a graph showing wear test results of sliding members of Examples 1 to 15 and Comparative Examples 1 to 4.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C25D 11/06 C25D 11/06 D 11/34 301 11/34 301 (72) Inventor Ryosuke Kawagoe 1-15 Nihonbashi, Chuo-ku, Tokyo No. 1 Japan Parkerizing Co., Ltd. (72) Inventor Hirofumi Michioka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yoshio Fuwa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Company Stock In-company (56) References JP-A-55-131176 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 22/00-22/86 C25D 11/06, 11/34

Claims (5)

(57) [Claims] 1. A method comprising: containing at least one selected from thiourea, thiosulfate, and thiocyanate; and at least one selected from molybdate, tungstate, and chromate. Characteristic surface treatment liquid for metal sliding members. 2. The surface treatment liquid for metal sliding members according to claim 1, further comprising a phosphate ion. 3. The surface treatment liquid for a metal sliding member according to claim 1, further comprising a fluoride ion. 4. A surface of a metal sliding member or a metal material for a metal sliding member is brought into contact with the surface treatment liquid according to claim 1 to form a chemical conversion film on the surface. A surface treatment method for a metal sliding member, comprising: 5. The surface of a metal sliding member or a metal material for a metal sliding member is subjected to an electrolytic treatment in the surface treatment liquid according to claim 1, and a chemical conversion film is formed on the surface. A surface treatment method for a metal sliding member, which is formed.