JP2011208215A - Member coated with sulfurized layer and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member coated with a sulfurized layer, which is superior in abrasion resistance and adhesiveness, has enhanced sliding characteristics, can lower aggressiveness against an opposite member and can prevent the damage of a substrate even in a severe environment, and to provide a method for manufacturing the member coated with the sulfurized layer at a low cost.SOLUTION: This member has a sulfurized layer 2 formed on a substrate 1, and a film 3 formed of a solid lubricant subsequently formed on the outermost surface. At this time, the solid lubricant is preferably formed from a fluorine-based resin, and is preferably applied onto the sulfurized layer and baked.

Description

  The present invention relates to a vulcanized layer-coated member and a method for producing the same, and more particularly to a member having a vulcanized layer formed as a hard layer on a substrate and a method for producing the same.

  Conventionally, in addition to sliding parts and machine parts such as automobiles that require wear resistance and seizure resistance, surfaces such as molds used under high surface pressure, iron sulfide and sulfur compounds by molten salt electrolysis, etc. There is known a method of improving the wear resistance and seizure resistance by forming a sulfurized layer made of (see, for example, Patent Document 1 and Patent Document 2).

Japanese Patent Laid-Open No. 6-220689 JP-A-10-204611

  However, in the conventional method, a surface treatment coating that satisfies all of the required wear resistance, adhesion, sliding properties, etc., on the surface of sliding parts such as automobiles, mechanical members, and dies is formed. In order to maximize the ability as a coating, it is essential to reinforce the substrate on which the coating is formed and to adjust the surface shape of the substrate.

  In addition, the generation layer (sulfurization layer) made of iron sulfide and sulfur compound described in Patent Document 1 is excellent in seizure resistance, galling, initial habituation, wear resistance, and fatigue resistance. There are problems of seizure resistance when a larger load is applied, aggression to the mating member, and damage to the base material (base material) when the generation layer is destroyed in a harsh environment.

  In addition, the sulfurized layer described in Patent Document 2 has high wear resistance, seizure resistance, and wear resistance, but the seizure resistance when a larger load is applied, and the aggressiveness to the mating member. In addition, there is a problem of damage to the base material (base material) at the time of destruction of the sulfurized layer in a harsh environment.

  Therefore, in view of such a conventional problem, the present invention is excellent in wear resistance and adhesion, can improve the sliding characteristics and can reduce the aggression to the mating member, in a harsh environment It is another object of the present invention to provide a vulcanized layer coating member and a method for producing the vulcanized layer coating member at a low cost, which can prevent damage to the substrate.

  As a result of intensive studies to solve the above problems, the present inventors have formed a sulfurized layer on a base material, and formed a film made of a solid lubricant on the sulfurized layer, thereby preventing wear. The low-sulfur-layer-coated member has excellent properties and adhesion, can improve the sliding characteristics, reduce the attacking property to the mating member, and prevent damage to the substrate even under harsh environments It has been found that it can be manufactured at a low cost, and the present invention has been completed.

  That is, the sulfur layer-coated member according to the present invention is characterized in that a sulfur layer is formed on a substrate and a film made of a solid lubricant is formed on the sulfur layer. In the vulcanized layer covering member according to the present invention, the fixed lubricant is preferably made of a fluorine-based resin, more preferably polytetrafluoroethylene.

  Further, the method for producing a laminated film-coated member according to the present invention comprises forming a sulfurized layer on a base material, applying a solid lubricant on the sulfurized layer, and baking the solid lubricant on the sulfurized layer. A film comprising a lubricant is formed. In addition, the sulfurized layer according to the present invention is preferably formed by immersing a base material in a molten salt bath and performing molten salt electrolysis, and the molten salt bath contains a molten salt composed of potassium thiocyanate and sodium thiocyanate. It is preferable to use it. The fixed lubricant is preferably made of a fluorine-based resin, and more preferably made of polytetrafluoroethylene.

  In the present specification, the “sulfurized layer” refers to a product layer made of iron sulfide and a sulfur compound on the surface of a substrate formed by molten salt electrolysis.

  According to the present invention, it is excellent in wear resistance and adhesion, can improve sliding characteristics and can reduce the attack on the mating member, and can prevent damage to the substrate even in harsh environments It is possible to produce a sulfurized layer covering member at a low cost. This sulfurized layer covering member can be used for molds, machine parts, automobile parts and the like.

It is sectional drawing which shows the structure of embodiment of the sulfurization layer coating | coated member by this invention. It is the schematic of the high-speed Falex friction abrasion tester used in the Example.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a sulfurated layer covering member and a method for manufacturing the same according to the present invention will be described below in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the embodiment of the vulcanized layer covering member according to the present invention includes a base material 1, a vulcanized layer 2 formed on the base material 1, and formed on the surface of the vulcanized layer 2. And a film 3 made of a solid lubricant.

  In this way, by forming a film (a layer with a low coefficient of friction) made of a solid lubricant such as a fluororesin on a sulfurized layer (a hard layer with high mechanical strength), the wear resistance and adhesion are improved. Excellent, can improve the sliding characteristics, can reduce the aggressiveness to the mating member, and can manufacture a vulcanized layer-coated member coated with a film that prevents damage to the substrate even in harsh environments .

  In other words, by forming a hard and high mechanical strength sulfurized layer on the substrate, and forming a low friction coefficient film made of a solid lubricant such as a fluororesin on the hardened layer, wear resistance and To produce a vulcanized layer-coated member that has excellent adhesion, can improve the sliding characteristics, can reduce the attack on the mating member, and can prevent damage to the substrate even in harsh environments Can do.

  As the fluororesin, it is preferable to use polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), tetrafluoroethylene (TFE) or the like.

  Here, first, in order to form a sulfurized layer on the base material, the metal member of the base material is immersed in a molten salt bath maintained at 160 to 240 ° C., and iron sulfide and iron are formed on the surface of the base material by molten salt electrolysis. A sulfurized layer (generated layer) made of a sulfur compound is obtained.

In the salt bath electrolysis, in a molten salt bath mainly composed of sodium thiocyanate (NaSCN) and potassium thiocyanate (KSCN) maintained at 160 to 240 ° C., pretreatment such as degreasing and acid washing, and further carburizing treatment, The substrate subjected to quenching treatment, tempering treatment, nitriding treatment, etc. is immersed, and direct-current electrolysis is performed using the substrate as an anode and the salt bath as a cathode.

  As a result, generation of iron ions is performed at the anode as shown in the following formula 1, and generation reaction of sulfur ions of the following two formulas is performed at the cathode, and by the sulfurization reaction of the following three formulas performed near the surface of the substrate, A sulfurized layer is generated on the surface of the substrate.

Fe → Fe ²⁺ + 2e (1)
SCN ⁻ + 2e → S ²⁻ + CN ⁻ (2)
Fe ²⁺ + S ²⁻ → FeS (3)

  In the present invention, a sulfurized layer is formed by the same chemical reaction as described above.

  The base material of the present invention is an iron measuring member whose surface is iron or an iron alloy, and is usually a machine such as gears, cylinders, pistons, etc. made of hardened steel, carburized steel or special steel. It is a part.

  Next, the base material on which the sulfurated layer is formed is sprayed with a solid lubricant made of a fluorine-based resin such as polytetrafluoroethylene on the surface of the sulfurized layer with a spray gun to a predetermined thickness. And baking at a temperature of 260 to 340 ° C. for about 0.1 to 3 hours. Thereby, a film made of a solid lubricant is formed on the sulfurized layer. The thickness of the film made of the solid lubricant is preferably 1 to 10 μm, and more preferably 1 to 6 μm.

  Hereinafter, examples of the sulfur-layer-coated member and the method for producing the same according to the present invention are described in detail.

[Example 1]
First, as a base material, a cylindrical Fabry pin with a diameter of 6.5 mm, which was mirror-polished after carburizing, quenching and tempering the steel type SCM415, was prepared.

As the molten salt bath, a composition composed of potassium thiocyanate (75% by mass) and sodium thiocyanate (25% by mass), which was maintained at 190 ° C., was used. The base material was immersed in the salt bath, and direct current electrolysis was performed for 10 minutes using the base material as an anode and the salt bath as a cathode at a current density of 3.2 A / dm ² .

  By the direct current electrolysis, a sulfurized layer made of iron sulfide and a sulfur compound having a thickness of about 5 μm was obtained on the substrate.

  Next, a solid lubricant made of polytetrafluoroethylene is applied to the surface of the nitrogen-containing chromium film on the outermost surface of the base material on which the sulfurized layer has been formed, based on a dry coating and baking method, at 300 ° C. for 2 hours. A solid lubricant film was formed on the sulfurized layer by firing the solid lubricant while maintaining the degree.

  When the surface of the thus obtained vulcanized layer-coated member (cylindrical vulcanized layer-coated fabric pin) was observed with a scanning electron microscope (SEM), the solid lubricant formed on the entire surface of the vulcanized layer was found to be confirmed. Moreover, when the cross section of the obtained sulfurized layer coating | coated member was observed by SEM, the layer of the solid lubricant about 2 micrometers thick was confirmed.

  Further, in order to evaluate the load bearing performance and sliding characteristics of the obtained vulcanized layer-coated Fabry pin, the rotatory drive 112 of the high-speed Falex frictional wear tester as shown in FIG. The upper part of the fabric pin 110 is fixed, and the side surface is sandwiched between the V-grooves of a pair of V blocks (blocks with carved quenching and tempering on the SCM 415) 111 (V-grooved block) 111. While rotating 110, increasing the load applied to the V block (indicated by an arrow L in the figure), and performing a non-lubricated frictional wear test, the appearance of the vulcanized layer coated Fabry pin and V block after the test was completed Was observed. In this test, the sliding speed was set to 0.1 m / s, and the maximum load at the end of the test was set to 15000 N. As an evaluation of the sliding characteristics, the friction coefficient μ at the end of the test was 0.079. Moreover, in the observation of the appearance of the Fabry pin (base material) after the test was completed, no seizure or damage was observed, and no damage to the sulfurized layer was observed.

[Example 2]
A sulfurated layer-coated member was produced in the same manner as in Example 1 except that the electrolysis time was increased and the thickness of the sulfurized layer was changed to 7 μm.

  When the surface of the sulfur layer coating member was observed with an SEM, a solid lubricant formed on almost the entire surface was confirmed. When the cross section of the sulfur layer coating member was observed with an SEM, a solid lubricant having a thickness of about 3 μm was observed. Layer was confirmed.

  Moreover, when the load bearing performance and sliding characteristics of the obtained laminated film-coated Fabry pin were evaluated by the same method as in Example 1, the friction coefficient μ at the end of the test was 0.081. Further, in the observation of the appearance of the Fabry pin after the test was completed, no seizure or damage was observed, and no damage to the laminated film was observed.

[Comparative Example 1]
Except that the film made of the solid lubricant was not formed on the sulfurized layer, a sulfurized layer layer-coated member (cylindrical sulfurized layer-coated fabric pin) was prepared in the same manner as in Example 1, Load performance and sliding properties were evaluated. In this test, the maximum load at the end of the test was set to 15000 N, but it was interrupted because seizure occurred at 7266 N. The friction coefficient μ at the end of the test was 0.199. Further, in the observation of the appearance of the Fabry pin after the test was completed, deformation due to plastic flow was observed, and seizure was observed.

[Comparative Example 2]
The load resistance performance and sliding characteristics of the same Fabry pins as in Example 1 (cylindrical Fabri pins with a diameter of 6.5 mm which were mirror-polished after carburizing, quenching and tempering steel type SCM415) were evaluated by the same method as in Example 1. As a result, the maximum load at the end of the test was set to 15000 N, but it was interrupted because seizure occurred at 4837 N. The friction coefficient μ at the end of the test was 0.336. Further, in the observation of the appearance of the Fabry pin after the test was completed, deformation due to plastic flow was observed, and seizure was observed.

DESCRIPTION OF SYMBOLS 1 Base material 2 Sulfurized layer 3 Film | membrane 110 which consists of solid lubricants Laminated | coated film-coated fabric pin 111 V block 112 Rotation drive 113 pin

Claims (8)

A sulfurated layer-coated member, wherein a sulfurized layer is formed on a substrate, and a film made of a solid lubricant is formed on the sulfurized layer. The said fixed lubricant consists of fluorine-type resin, The sulfurated layer coating | coated member of Claim 1 characterized by the above-mentioned. The said fixed lubricant consists of polytetrafluoroethylene, The sulfurated layer coating | coated member of Claim 1 characterized by the above-mentioned. After forming the sulfurized layer on the substrate, a solid lubricant is applied on the sulfurized layer and baked to form a film made of the solid lubricant on the sulfurized layer. A method for producing a sulfur layer-coated member. 5. The method for producing a sulfur-coated layer-coated member according to claim 4, wherein the sulfur-containing layer is formed by immersing the base material in a molten salt bath and performing molten salt electrolysis. The said sulfurization layer is formed by using the molten salt which consists of potassium thiocyanate and sodium thiocyanate as said molten salt bath, The sulfurization layer coating | coated member of Claim 4 or 5 characterized by the above-mentioned. Manufacturing method. The method for manufacturing a sulfur-coated layer covering member according to any one of claims 4 to 6, wherein the fixed lubricant is made of a fluororesin. The method for producing a sulfur-coated layer covering member according to any one of claims 4 to 7, wherein the fixed lubricant is made of polytetrafluoroethylene.

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