JP6234803B2 - Pressure plate, brake pad using the same, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a brake pad, a pressure plate which is a main part of the brake pad, and a manufacturing method thereof.

  A brake pad 1 as shown in FIG. 4 is used for a disc brake of an automobile or the like. The brake pad 1 includes a pressure plate 2 made of a ferrous metal and a friction material 3 bonded to the surface of the pressure plate 2.

  In such a disc brake, the brake pad 1 is disposed so as to sandwich the disc brake rotor that rotates with the wheel, and the braking force is obtained by pressing the brake pad 1 against the disc brake rotor and generating a frictional force. At this time, since a large shearing force acts between the pressure plate 2 and the friction material 3 of the brake pad 1, the adhesion between the pressure plate 2 and the friction material 3 requires an adhesive strength that can withstand the shearing force. Is done.

  As a method for satisfying such a requirement, for example, the surface of the pressure plate 2 is roughened by blasting (surface grinding) such as drive blast or wet blasting to obtain a surface shape having an uneven structure. A method of bonding the pressure plate 2 and the friction material 3 is known. When such a concavo-convex structure exists, the adhesive enters the concave portion when the pressure plate 2 and the friction material 3 are bonded, and a high adhesive strength is obtained by the anchor effect obtained thereby. However, even when the pressure plate 2 and the friction material 3 are bonded by such a method, if rust is generated at the bonding interface between the pressure plate 2 and the friction material 3, the adhesive strength is reduced. There is.

For this reason, it is a common practice to improve the primary rust-preventing effect by applying a chemical conversion treatment to the roughened surface to form an iron phosphate film and preventing the occurrence of rust during the manufacturing process. For example, Japanese Patent Application Laid-Open No. 2003-148528 uses a treatment liquid obtained by adding a specific surfactant or a fluorine-based cleaning agent to a specific phosphate solution, and alumina abrasive grains having an average particle size of 300 μm. Thus, a technique is described in which a wet blast treatment is performed with an air pressure of 0.45 MPa and a treatment time of 240 seconds to simultaneously degrease the surface of the pressure plate, roughen the surface, and form an iron phosphate film. Also, in Japanese Patent No. 4563285, the surface of the pressure plate is roughened to about 20 μm with a 10-point average roughness Rz by drive blasting or wet blasting, and then the surface of the pressure plate is phosphorylated by chemical conversion. A technique for forming a phosphate film such as an iron oxide film (film weight = 0.6 g / m ² ) is described. However, only the formation of a phosphate film may cause rust on the surface of the pressure plate depending on the usage environment, resulting in decreased adhesion strength with the friction material, and sufficient corrosion resistance (permanent rust prevention effect) It is difficult to ensure. Further, the technique described in Japanese Patent Application Laid-Open No. 2003-148528 has a problem in terms of safety and environmental protection because a fluorine-based cleaning agent is used as the cleaning liquid. On the other hand, in the technique described in Japanese Patent No. 4563285, in order to obtain high adhesive strength, it is essential to use a specific adhesive made of a phenol resin novolac-modified polybenzoxacid resin, There is a limit to industrial use.

  On the other hand, Japanese Patent Publication No. 53-47218 discloses a pressure plate in a mixed gas atmosphere composed of an endothermic metamorphic gas and ammonia gas without performing wet blasting or rust prevention with a phosphate solution. A technique of gas soft nitriding with a treatment temperature of 500 ° C. to 650 ° C. and a treatment time of 0.5 to 8 hours is described. According to this technique, the surface of the pressure plate is in a surface state having fine protrusions having a surface roughness (JIS 0610) of 5 μm to 50 μm, and a nitrogen compound layer having excellent corrosion resistance is formed. Therefore, it is said that adhesive strength and corrosion resistance can be improved at the same time. However, it is difficult to sufficiently improve the surface roughness of the pressure plate only by the gas nitrocarburizing treatment. Usually, the formation of pores on the surface is limited, so that the adhesion strength with the friction material is greatly increased. It cannot be improved.

  On the other hand, in Japanese Patent No. 3124433, treatment is performed at a temperature of 570 ° C. to 610 ° C. for 40 minutes to 150 minutes in a salt bath mainly containing cyanate and cyanate and having a cyan concentration of 0.1% to 6%. A technique for forming a nitrogen compound layer on the surface of a pressure plate by performing a salt bath soft nitriding treatment is described. Unlike the gas soft nitriding treatment, the salt bath soft nitriding treatment can greatly improve the surface roughness of the pressure plate due to the elution of iron components in the surface layer of the pressure plate into the salt bath. As a result, the adhesive strength can be greatly improved. However, in the salt bath soft nitriding treatment, it is necessary to use an extremely toxic cyan compound even at a low concentration, which is problematic in terms of safety or environmental protection.

  Japanese Patent No. 4563285 describes a technique in which the surface of the pressure plate is subjected to blasting treatment such as wet blasting or drive blasting, and then subjected to soft nitriding treatment on the surface. There is no description about the conditions of the treatment and soft nitriding treatment.

  Under such circumstances, it is proposed to improve the adhesion strength and corrosion resistance of the surface by forming a halogenated film on the surface of the pressure plate using a halogen compound and then performing nitriding or gas soft nitriding. Has been. For example, Japanese Patent Laid-Open No. 2012-251216 discloses an activation treatment at a treatment temperature of 350 ° C. to 450 ° C. in a fluorine gas atmosphere to form a fluoride film layer, and then a treatment temperature of 300 ° C. to 600 ° C. The thickness of the nitrogen compound layer is reduced to the surface of the nitrogen compound layer of 5 μm to 20 μm by performing nitriding treatment or gas soft nitriding treatment for 30 minutes to 60 minutes and cooling in a non-oxidizing atmosphere. A technique for forming a porous layer having a thickness of 40% or more of the thickness is described. Further, in Japanese Patent No. 5044712, a halogen element is diffused to a depth of 1 μm or more from the surface of the pressure plate by halogenation treatment, and then subjected to nitridation treatment in a gas atmosphere not containing a carbon source. Instead of the N—C system, a Fe—N system first compound layer and a second compound layer formed on the first compound layer, having a higher nitrogen concentration than the first compound layer and having irregularities on the surface A technique for forming a compound layer consisting of is described.

  In the techniques described in these documents, since the nitriding treatment or the gas soft nitriding treatment is performed in a state where the surface of the pressure plate is activated by the halogenation treatment, nitrogen can be penetrated deeper. As a result, it is possible not only to form a concavo-convex shape or a porous layer sufficient for improving the adhesive strength on the surface of the pressure plate, but also to form a thick nitrogen compound layer, which greatly increases its corrosion resistance. Can be improved. However, halogen elements are generally highly toxic, and even the techniques described in these documents have problems in terms of safety and environmental protection.

JP 2003-148528 A Japanese Patent No. 4563285 Japanese Examined Patent Publication No. 53-47218 Japanese Patent No. 3124433 JP 2012-251216 A Japanese Patent No. 5044712

  The present invention relates to a pressure plate that does not use harmful substances such as cyanide compounds and fluorine compounds and has high adhesion strength to a friction material and excellent corrosion resistance regardless of the type of adhesive, and the pressure plate. It is an object of the present invention to provide a brake pad including the above and a manufacturing method thereof.

One aspect of the present invention relates to a method for manufacturing a ferrous metal pressure plate having a surface to be bonded to which a friction material is bonded.
A roughening step of roughening at least the adherend surface of the pressure plate by blasting and removing an oxide film present on the adherend surface;
A drying and / or washing step for drying and / or washing the pressure plate so that an oxide film is not formed at least on the adherend surface after the roughening step;
After the drying and / or cleaning step, a heat treatment step of gas soft nitriding the pressure plate in a state where at least the oxide film is not present on the adherend surface;
It is characterized by providing.

  The arithmetic average roughness Ra of the adherend surface of the pressure plate after the heat treatment step is preferably in the range of 1.5 μm to 8.0 μm, and the ten-point average roughness Rz is preferably in the range of 10 μm to 40 μm. Moreover, it is preferable that the height difference between the most protruding portion and the most recessed portion of the adherend surface is 5 μm to 50 μm.

  In the blast treatment, a grid having a particle size in the range of # 24 to # 100 is used as an abrasive, the air pressure is in the range of 0.1 MPa to 0.5 MPa, and the treatment time is in the range of 10 seconds to 600 seconds. It is preferable to set.

  As the grid, it is more preferable to use at least one selected from corundum including white alumina, brown alumina, black silicon carbide, and green silicon carbide.

  When wet blasting is used as the blasting treatment, the grid concentration of the grid is preferably 5% by mass to 30% by mass.

  When wet blasting is used as the blasting treatment, in the drying and / or cleaning step, after drying the pressure plate, at least the adherend surface may be cleaned using a hydrocarbon-based cleaning liquid. preferable.

  In the gas soft nitriding treatment, a mixed gas atmosphere composed of ammonia gas and carburizing gas is used, the treatment temperature is set in a range of 500 ° C. to 590 ° C., and the treatment time is set in a range of 0.1 hour to 4 hours. Is preferred.

  The brake pad of the present invention is obtained by adhering the friction material to the adherend surface of the pressure plate obtained by the production method of the present invention via an adhesive.

  Another aspect of the present invention relates to a pressure plate whose main component is a brake pad, a ferrous metal base material, an adherend surface to which a friction material is bonded, and a surface of the base material. A nitrogen diffusion layer formed on at least the adherend surface, and an arithmetic average roughness Ra in the range of 1.5 μm to 8.0 μm formed on the nitrogen diffusion layer, and a ten-point average roughness A nitrogen compound layer having an Rz in the range of 10 μm to 40 μm and a porous layer formed on the outermost surface of the nitrogen compound layer and having a thickness in the range of 3.0 μm to 20.0 μm .

  The thickness of the nitrogen compound layer is preferably 5 μm to 25 μm.

  In the nitrogen compound layer, the difference in height between the most protruding portion and the most recessed portion is preferably 5 μm to 50 μm.

  The brake pad of this invention is comprised by the pressure plate of this invention, and the friction material adhere | attached on the to-be-adhered surface via the adhesive agent.

  According to the present invention, a pressure plate that can be bonded to a friction material with high adhesive strength without using a cyanide compound or a fluorine compound, and has excellent corrosion resistance, and such excellent characteristics. A brake pad with a pressure plate is provided. Further, according to the present invention, such a brake pad can be manufactured regardless of the type of adhesive used for bonding the pressure plate and the friction material. Thus, the industrial significance of the present invention is extremely great.

FIG. 1 is an SEM image (magnified 2000 times) showing a cross section in the vicinity of the surface of the pressure plate obtained in Example 1. FIG. 2 is an SEM image (2000 times) showing a cross section near the surface of the pressure plate obtained in Comparative Example 2-1. FIG. 3 is an SEM image (2000 magnifications) showing a cross section in the vicinity of the surface of the pressure plate obtained in Comparative Example 2-3. FIG. 4 is a perspective view showing an example of a conventional brake pad.

  As a means to improve the adhesive strength between the pressure plate and the friction material, the surface to be bonded of the pressure plate that constitutes the brake pad is roughened by blasting regardless of whether it is wet blast or drive blast. It can be considered that a nitrogen compound layer is formed on the adherend surface by gas soft nitriding. However, in practice, sufficient bonding strength cannot be obtained simply by combining blasting and gas soft nitriding.

  As a result of further research on the combination of blasting and gas soft nitriding, the present inventors have found that a very thin oxide film is formed on the surface of the pressure plate immediately after blasting and immediately before gas soft nitriding. It was found that this oxide film hinders nitrogen penetration in gas soft nitriding. More specifically, conventionally, when wet blasting is performed on the surface of the pressure plate, moisture remains on the roughened surface, so the pressure plate is dried, In some cases, the pressure plate is washed and dried in order to remove fine particles adhering to the surface of the pressure plate. Here, drying of the pressure plate is generally performed by blowing hot air on the surface after the roughening, but during drying or after the gas soft nitriding treatment after drying, An oxide film having a thickness of about 1 μm to 5 μm is formed on the surface of the pressure plate. As a result, in either case of wet blasting or drive blasting, a very thin oxide film is re-formed on the surface of the pressure plate from which the oxide film has been removed. I got the knowledge that it was hindered.

  The present invention has been completed based on such knowledge, and adopts a blasting treatment, preferably a combination of a wet blasting treatment and a gas soft nitriding treatment, as means for strengthening the bonding between the pressure plate and the friction material. The surface of the pressure plate after blasting is prevented from being oxidized, and gas soft nitriding is performed in the absence of an oxide film on the surface, thereby improving the adhesive strength between the pressure plate and the friction material, and the pressure. It is characterized by improving the corrosion resistance of the plate.

[1] Manufacturing method of pressure plate and brake pad The manufacturing method of the pressure plate and brake pad of the present invention comprises roughening at least the adherend surface of the pressure plate by blast treatment, preferably wet blast treatment, After removing the oxide film present on the bonding surface, the bonded surface is dried and / or washed so that the oxide film is not formed, and gas soft nitriding is performed in a state where the oxide film is not present on the bonded surface of the pressure plate. It is characterized by that. In addition, in this invention, it is not prevented that surfaces other than a to-be-adhered surface are processed simultaneously.

  Thus, when there is no oxide film on the surface of the pressure plate, that is, when the surface cleanliness is extremely high, the reactivity of the surface of the pressure plate is high as in the case of halogenation treatment, and the active state Therefore, it is possible to infiltrate more nitrogen into a deeper position by performing the gas soft nitriding treatment in this state. As a result, the surface state of the pressure plate after the gas soft nitriding treatment is complicated by a porous layer consisting of innumerable pores formed by the gas soft nitriding treatment at the outermost part of the uneven structure formed by the blasting treatment. Structure. For this reason, at the time of adhesion | attachment of a pressure plate and a friction material, a high anchor effect can be acquired and it becomes possible to improve adhesive strength. Further, as described above, in the gas soft nitriding treatment, more nitrogen can be penetrated to a deeper position, so that the nitrogen compound layer can be formed thicker and its corrosion resistance can be improved. It becomes.

(1) Pressure plate material The pressure plate constituting the brake pad of the present invention is formed by sheet metal pressing or the like. The material of the pressure plate is not particularly limited, and a known iron metal material can be used. For example, a hot-rolled sheet for automobiles such as SAPH400 and SAPH440 and a workable hot-rolled high-tensile steel sheet for automobiles such as SPFH590 can be used.

(2) Roughening step In the present invention, as a means for roughening the surface of the iron-based metal pressure plate and removing the oxide film existing on the surface, blasting, more specifically, wet blasting and Adopt drive last. By such a roughening treatment, a concavo-convex structure having an arithmetic average roughness Ra and a ten-point average roughness Rz as described below can be formed on the surface of the pressure plate.

  Among such blasting processes, the drive blasting requires cleaning the surface of the pressure plate after the processing. In addition, the drive last involves the generation of a large amount of dust, and in order to protect the health of workers and ensure safety, it is essential to operate a dust collection facility. Further, the drive last is a dry process, and the surface oxidation proceeds immediately after the oxide film is removed, so that it may be difficult to perform the gas soft nitriding process in the absence of the oxide film. On the other hand, since wet blasting is a wet process, the process surface can be cleaned simultaneously with the roughening process, and the cleaning process after the process can be omitted. In addition, there is no problem due to the generation of dust, and oxidation does not progress during processing. For this reason, it is preferable to employ wet blasting as the roughening treatment.

  In the present invention, the conditions for the blast treatment are not particularly limited, but in order to bond the pressure plate and the friction material with high adhesive strength, the arithmetic average of the pressure plate surface after the gas soft nitriding treatment is used. The roughness Ra is preferably in the range of 1.5 μm to 8.0 μm, and the ten-point average roughness Rz is preferably in the range of 10 μm to 40 μm. For this reason, after the blast treatment, the arithmetic average roughness Ra of the surface of the pressure plate is preferably in the range of 0.5 μm to 10 μm, more preferably in the range of 1.0 μm to 7.0 μm, and the ten-point average roughness The thickness Rz is preferably in the range of 3 μm to 40 μm, more preferably in the range of 10 μm to 37 μm. The arithmetic average roughness Ra and the ten-point average roughness Rz can be measured with a surface roughness measuring machine.

  Conditions for controlling the arithmetic average roughness Ra and ten-point average roughness Rz of the pressure plate surface within the above ranges are the material and size of the pressure plate, the type of abrasive (projection material), the performance of the blasting device, etc. However, it is generally preferable to select as follows.

(Abrasive)
The abrasive can be appropriately selected from spherical particle-shaped shots and beads, or a cornered non-spherical particle grid, but it is preferable to use a grid having hard particles and high processing power. In particular, it is more preferable to use at least one kind of grid selected from corundum such as white alumina, brown alumina, black silicon carbide, and green silicon carbide, and among these, it is preferable to use white alumina with less residual impurities. Further preferred.

  When a grid is used as the abrasive, the particle size (grid number) is preferably in the range of # 24 to # 100, more preferably in the range of # 36 to # 80, and further preferably in the range of # 46 to # 60. Is used. That is, a grid having an average particle diameter of preferably 130 μm to 730 μm, more preferably 180 μm to 520 μm, and still more preferably 260 μm to 360 μm is used. When the grid number is less than # 24 (when the average particle size exceeds 730 μm), the processing force of the grid is too large. Even if the surface of the pressure plate is roughened by blasting to form an uneven structure, The edge may be rounded and a sufficient anchor effect may not be exhibited. In addition, the blasting apparatus itself is polished, and in some cases, a hole may be formed in the inner wall of the apparatus. On the other hand, when the grid number exceeds # 100 (when the average particle size is less than 130 μm), the processing force is too small, and the surface of the pressure plate may not be sufficiently roughened.

(Air pressure)
The air pressure for projecting the abrasive onto the pressure plate is preferably in the range of 0.1 MPa to 0.5 MPa, more preferably in the range of 0.2 MPa to 0.45 MPa, and still more preferably in the range of 0.3 MPa to 0.4 MPa. Range. If the air pressure is less than 0.1 MPa, the surface of the pressure plate may not be sufficiently roughened. On the other hand, if the pressure exceeds 0.5 MPa, the surface of the pressure plate may be roughened by blasting, and even if an uneven structure is formed, the edge may be rounded and a sufficient anchor effect may not be exhibited. . In addition, the blasting apparatus itself is polished, and in some cases, a hole may be formed in the inner wall of the apparatus.

(processing time)
The processing time of the blast treatment is preferably set in the range of 10 seconds to 600 seconds, more preferably in the range of 15 seconds to 450 seconds, and still more preferably in the range of 20 seconds to 300 seconds. If the treatment time is less than 10 seconds, the surface of the pressure plate may not be sufficiently roughened. On the other hand, even if it exceeds 600 seconds, not only the effect cannot be obtained, but also the edge of the concavo-convex structure formed by the blasting process may be rounded, and the sufficient anchor effect may not be exhibited. .

(Grid density)
When the surface is roughened by wet blasting, the grid concentration (slurry concentration) of the grid described above is preferably in the range of 5% by mass to 30% by mass, more preferably in the range of 10% by mass to 25% by mass. More preferably, it is set as the range of 15 mass%-20 mass%. If the grid concentration is less than 5% by mass, the surface of the pressure plate may not be sufficiently roughened. On the other hand, if it exceeds 30% by mass, the grid may be clogged in the wet blasting apparatus.

(Processing liquid)
Similarly, when the surface is roughened by wet blasting, tap water or Top Alclean (Okuno Pharmaceutical Co., Ltd.) or Chemicleaner (Nihon CB Chemical Co., Ltd.) is used as the treatment liquid. An aqueous alkali solution can be used.

  The temperature of the treatment liquid is preferably adjusted in a range of 5 ° C. to 90 ° C., more preferably in a range of 20 ° C. to 70 ° C. in a state where it is mixed with an abrasive, that is, in a slurry state. If the temperature of the alkaline aqueous solution is within such a range, degreasing and primary rust prevention can be performed simultaneously by wet blasting.

(3) Drying and / or washing step When the surface is roughened by wet blasting, it can be dried while preventing oxidation of the surface including the adherend surface as a means for drying the surface of the pressure plate. Means need to be used. Examples of such means include vacuum drying, compressed air drying, and hot air drying. However, when hot air drying is employed as the drying means, an oxide film may be immediately formed on the adherend surface depending on the temperature of the hot air, the amount of spraying, and the like. In order to prevent this, it is preferable to replace the moisture remaining on the surface by using a hydrocarbon-based cleaning liquid described below and move it physically and then dry it with hot air.

  In addition, when the surface is roughened by wet blasting, the surface of the pressure plate after the treatment is in a very complicated surface state, so moisture cannot be completely dried only by drying by the above means. In some cases, the time required for drying becomes longer and the productivity deteriorates. For this reason, it is preferable to wash | clean the surface of a pressure plate with a hydrocarbon type washing | cleaning liquid with little corrosiveness to a metal after a drying process. Thereby, the remaining water can be completely removed in a short time without oxidizing the surface of the pressure plate.

  Examples of such a hydrocarbon-based cleaning liquid include alcohol-based mixtures such as ethanol, octanol, and isopropyl alcohol (IPA). Among these, it is preferable to use an octanol-based mixture having a high moisture removal effect and a high boiling point.

  In addition, the washing | cleaning method by a hydrocarbon type washing | cleaning liquid is not specifically limited, A well-known method is employable, For example, it can wash | clean by immersing a pressure plate in a hydrocarbon type washing | cleaning liquid.

  On the other hand, when the surface is roughened by drive last, the surface of the pressure plate is removed with tap water or Top Alclean (Okuno Pharmaceutical Co., Ltd.) It is necessary to wash with an alkaline aqueous solution such as Chemicleaner (manufactured by Nippon C.B. Chemical Co., Ltd.) and dry so that an oxide film is not formed on at least the adherend surface. However, since the surface of the pressure plate after the roughening treatment is in a very complicated surface state, it takes a long time to completely remove the remaining water. For this reason, as in the case of wet blasting, it is preferable to clean the surface of the pressure plate after drying with a hydrocarbon-based cleaning liquid.

(4) Heat treatment step In the present invention, after the drying and / or cleaning step, it is important to perform gas soft nitriding treatment in a state where no oxide film is present on the surface (surface to be bonded) of the pressure plate. Here, the state in which no oxide film is present is a state in which the oxide film is not present on the surface (surface to be bonded) of the pressure plate, or even if an oxide film is present, its thickness is extremely thin and less than 1 μm. It means that. Thus, by performing the gas soft nitriding process with the surface plate having a very high cleanliness, it is possible to infiltrate more nitrogen into a deeper position. As a result, the nitrogen compound layer and its outermost porous layer can be formed thicker than those obtained by gas soft nitriding in the presence of an oxide film. It can be made to have excellent corrosion resistance.

  In the gas soft nitriding method of the present invention, a gas nitriding furnace similar to the conventional one can be used. The conditions for the gas nitrocarburizing treatment should be appropriately selected according to the material of the target pressure plate and the performance of the gas nitrocarburizing furnace. The thicknesses of the nitrogen diffusion layer and the nitrogen compound layer are predetermined. From the viewpoint of controlling within this range, the following conditions are preferable.

  The treatment temperature in the gas soft nitriding treatment is preferably in the range of 500 ° C to 590 ° C, and more preferably in the range of 530 ° C to 590 ° C. When the processing temperature is less than 500 ° C., a nitrogen diffusion layer and a nitrogen compound having a sufficient thickness cannot be formed. On the other hand, when it exceeds 590 ° C., hard and brittle austenite is formed in the material, and the nitrogen diffusion layer and the nitrogen compound layer may not be stably formed.

  The holding time at the treatment temperature is preferably in the range of 0.5 hours to 4 hours, more preferably in the range of 1 hour to 3 hours. When the treatment time is less than 0.5 hour, a nitrogen diffusion layer and a nitrogen compound layer having a sufficient thickness cannot be formed. On the other hand, even if the treatment time exceeds 4 hours, the nitrogen diffusion layer and the nitrogen compound layer hardly grow any more, so the productivity deteriorates.

As the nitrogen supply source, NH ₃ that is a nitriding gas can be used. On the other hand, the carbon supply source is not particularly limited as long as it is a carburizing gas. For example, hydrocarbons containing alcohol such as CH ₃ OH, CO, CO ₂ or the like can be used. In particular, from the viewpoint of efficiently forming the nitrogen diffusion layer and the nitrogen compound layer at low cost, it is preferable to supply nitrogen and carbon by a mixed gas of NH ₃ and CH ₃ OH. In this case, the flow rate of NH ₃ in the range of ^{4.5m 3 /h~5.5m 3 / h, CH} 3 OH flow of 3.0 × 10 ^-5 m ³ of /H～1.0×10 ^-4 A range of m ³ / h is preferred.

  The pressure in the gas nitriding furnace can be adjusted so as to be about 0.2 kPa to 1.0 kPa, usually about 0.5 kPa to 0.7 kPa, higher than the atmospheric pressure, as in the general gas soft nitriding treatment. preferable.

(5) Adhesion process The adhesion process is performed by applying an adhesive to the adherend surface to which the friction material is adhered, among the surfaces of the pressure plate after gas soft nitriding, and bonding the preformed friction material to the adherend surface. This is a step of bonding the pressure plate and the friction material by bringing the surfaces into contact with each other and heat compression molding. The method of bonding the pressure plate and the friction material in this step and the conditions thereof are basically the same as those in the prior art, so the description thereof will be omitted and the following description will focus on the features of the present invention.

  In the present invention, the adherend surface of the pressure plate has a complicated structure in which a porous layer composed of innumerable pores formed by gas soft nitriding is present on the outermost surface of the concavo-convex structure formed by blasting. Therefore, when the pressure plate and the friction material are bonded, a high anchor effect acts between them. As a result, the pressure plate and the friction material can be bonded with high adhesive strength without applying a primer to the adherend surface of the pressure plate.

  Moreover, since the to-be-adhered surface of the pressure plate of this invention is equipped with such a complicated structure, a high anchor effect can be acquired regardless of the kind of adhesive agent. That is, according to the present invention, the pressure plate and the friction material are bonded with a high adhesive strength even when a powder-based adhesive is used or when a solvent-based adhesive is used. Can do. However, in order to obtain high adhesive strength efficiently, the adhesive is required to easily reach the innermost part of the uneven structure on the surface of the pressure plate. For this reason, as the solvent-based adhesive, an adhesive made of a thermosetting resin such as an epoxy resin, a phenol resin or a modified resin thereof, or a mixture thereof is preferable, and the viscosity of these adhesives is 1 mPa to 100 mPa. It is more preferable to use it after adjusting the range. Similarly, the powder-based adhesive is preferably an adhesive made of a thermosetting resin such as an epoxy resin, a phenol resin, or a modified resin thereof, or a mixture thereof, and the average particle diameter of the powder is 20 μm to What is in the range of 100 micrometers is more preferable.

  The adhesive application means needs to be able to reach the innermost part of the uneven structure on the surface of the pressure plate from the viewpoint of obtaining a high anchor effect. Specifically, when a solvent-based adhesive is used, it is preferably sprayed using a spray gun or the like. Moreover, when using a powder-type adhesive agent, it is preferable to apply electrostatically.

[2] Brake pad (1) Pressure plate The pressure plate constituting the disc brake of the present invention includes a nitrogen diffusion layer formed on at least an adherend surface of the surface of a base material made of iron-based metal, and the nitrogen diffusion. A nitrogen compound layer formed on the layer and having an arithmetic average roughness Ra in the range of 1.5 μm to 8.0 μm and a ten-point average roughness Rz in the range of 10 μm to 40 μm. A porous layer having a thickness in the range of 3.0 μm to 20.0 μm is formed on the outermost surface portion of the nitrogen compound layer.

  That is, the pressure plate according to the present invention has a concavo-convex structure formed by wet blasting on the surface (at least an adherend surface) and an infinite number of gas nitriding treatments formed on the outermost surface of the concavo-convex structure. It has a complicated structure with a porous layer composed of pores. For this reason, the high anchor effect is acquired at the time of adhesion | attachment with a friction material, and it becomes possible to adhere | attach a pressure plate and a friction material with high adhesive strength. Further, in the pressure plate of the present invention, since the nitrogen compound having excellent corrosion resistance is sufficiently thick and the pores constituting the porous layer do not penetrate this nitrogen compound layer, excellent corrosion resistance is exhibited.

(Nitrogen diffusion layer)
The nitrogen diffusion layer is a layer formed by nitrogen being supersaturated in the base material during gas soft nitriding. The thickness of this nitrogen diffusion layer is preferably adjusted in the range of 20 μm to 500 μm, more preferably in the range of 50 μm to 200 μm. If the thickness of the nitrogen diffusion layer is less than 20 μm, a sufficient rust prevention effect may not be obtained. On the other hand, if it exceeds 500 μm, the dimensional accuracy of the pressure plate may be deteriorated, or the time required for forming the nitrogen diffusion layer may be prolonged and productivity may be deteriorated.

The nitrogen diffusion layer is the same as the practical hardened layer depth (practical, ND-P) defined by JSHS1001, and means a depth up to a hardness higher by HV50 than the hardness of the base material. The thickness of the nitrogen diffusion layer can be determined by performing a tempering treatment at 300 ° C., and measuring the thickness of the portion where the Fe ₄ N (γ ′) acicular crystals are deposited.

(Nitrogen compound layer)
The nitrogen compound layer is a layer made of Fe ₃ N or the like and has excellent corrosion resistance. In particular, in the present invention, since the gas soft nitriding treatment is performed in the state where the oxide film is not present on the surface of the pressure plate, the nitrogen compound layer is compared with the case where the gas soft nitriding treatment is performed in the state where the oxide film is present. Can be formed thicker, and the corrosion resistance can be further improved.

  The surface roughness of the nitrogen compound layer is an arithmetic average roughness Ra in the range of 1.5 μm to 8.0 μm, preferably in the range of 1.7 μm to 6.5 μm, more preferably in the range of 2.0 μm to 5.0 μm. In addition, the ten-point average roughness Rz needs to be in the range of 10 μm to 40 μm, preferably in the range of 11 μm to 35 μm, more preferably in the range of 13 μm to 30 μm. When the average roughness of the surface of the nitrogen compound layer is less than 1.5 μm in arithmetic average roughness Ra, or less than 10 μm in ten-point average roughness Rz, sufficient anchor effect cannot be obtained and sufficient adhesion is achieved. In some cases, strength cannot be obtained. On the other hand, if the average roughness of the surface of the nitrogen compound layer exceeds 8.0 μm in arithmetic average roughness Ra or exceeds 40 μm in ten-point average roughness Rz, the convex portion of the concavo-convex structure applies the adhesive. It protrudes from the adhesive layer formed by doing this, and similarly, sufficient adhesive strength may not be obtained.

  The thickness of the nitrogen compound layer is preferably adjusted in the range of 5 μm to 25 μm, more preferably in the range of 7 μm to 18 μm. If the thickness of the nitrogen compound layer is less than 5 μm, pores formed in the outermost portion of the nitrogen compound layer may penetrate the nitrogen compound layer and reach the nitrogen diffusion layer, so that sufficient corrosion resistance is obtained. May not be possible. On the other hand, if it exceeds 25 μm, not only the effect cannot be obtained, but also the time required for the gas soft nitriding process becomes long and productivity deteriorates. The thickness of the nitrogen compound layer can be measured by treating the cross section of the pressure plate with a nital liquid and then observing the cross section with an optical microscope.

  Moreover, it is preferable that the height difference (distance in the vertical direction) between the most protruding portion (most convex portion) and the most concave portion (most concave portion) in the surface layer portion of the nitrogen compound layer is 5 μm to 50 μm. More preferably, it is 10 μm to 30 μm. When the height difference between the most convex part and the most concave part is in such a range, the adhesive strength and the corrosion resistance can be further improved together with the action of the porous layer described later.

(Porous layer)
The porous layer is a layer composed of innumerable pores formed when nitrogen atoms that have entered the base material by gas soft nitrogen treatment are recombined inside the base material and released as nitrogen gas. In the present invention, as described above, the gas soft nitriding treatment is performed in a state where the oxide film is not present on the surface of the pressure plate, and compared with the case where the gas soft nitriding treatment is performed in the state where the oxide film is present. A lot of nitrogen can be penetrated deeper. For this reason, a porous layer in which more pores are formed to a deeper position can be formed. In addition, since such a porous layer is adjusted so that it may be formed in the outermost part of a nitrogen compound layer, the pore which comprises this porous layer penetrates a nitrogen compound layer, and reaches | attains a nitrogen diffusion layer The presence of this porous layer or pore does not reduce the corrosion resistance.

  The thickness of the porous layer is adjusted in the range of 3.0 μm to 20.0 μm, preferably in the range of 5.0 μm to 15.0 μm, more preferably in the range of 7.0 μm to 10.0 μm. If the thickness of the porous layer is less than 3.0 μm, the anchor effect cannot be sufficiently obtained, and thus the adhesive strength cannot be improved. On the other hand, if it exceeds 20.0 μm, some of the pores constituting the porous layer may penetrate the nitrogen compound layer and reach the nitrogen diffusion layer, resulting in a decrease in corrosion resistance. The thickness of the porous layer can be measured by the same method as the thickness of the nitrogen compound layer.

(2) Brake pad The brake pad of this invention is comprised from the pressure plate mentioned above and the friction material adhere | attached on the to-be-adhered surface of this pressure plate via the adhesive agent. For this reason, in the brake pad of this invention, it becomes possible to adhere | attach a friction material firmly with high adhesive strength on the to-be-adhered surface of a pressure plate. Moreover, since the surface of this pressure plate is equipped with the outstanding corrosion resistance, it can prevent effectively that adhesive strength falls because rust generate | occur | produces.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Confirmation test of adhesive strength]
First, a steel plate made of SAPH400 having a thickness of 1.6 mm, a width of 25 mm, and a length of 100 mm is subjected to wet blasting, gas soft nitriding, and the like. A sample was obtained by adhering a “side steel plate” using a powder-based adhesive or a solvent-based adhesive, and a test for confirming the adhesive strength was performed.

(Example 1-1)
The steel plate was put into a rotating barrel type wet blasting apparatus (Mako Co., Ltd., MSB-S5), and a white alumina grid (grid number: # 60) and an alkaline cleaning solution (Nippon CB Chemical Co., Ltd., Chemicleaner 576). Wet blasting was performed using a slurry having a concentration of 15% by volume. At this time, the air pressure was 0.10 MPa, the treatment time was 180 seconds, the temperature of the slurry was room temperature to 90 ° C., and the pH value was 8 to 11 (based on the liquid temperature of 25 ° C.). After wet blasting, the surface roughness of the steel sheet was measured with a surface roughness measuring machine (manufactured by Kosaka Laboratory, Surfcoder SE2300 / DR-250X). As a result, the ten-point average roughness Rz was 5.5 μm. Yes, the arithmetic average roughness Ra was 1.0 μm.

  After the wet blasting treatment, the steel plate was taken out from the rotating barrel type wet blasting device, and immediately compressed air of normal temperature to 30 ° C. was sprayed to dry the surface. Furthermore, the steel sheet was cleaned by immersing it in a hydrocarbon-based cleaning liquid (manufactured by Nippon Grease Co., Ltd., AY Clean A-78L) under reduced pressure to completely remove moisture remaining on the surface.

Immediately after the drying and cleaning steps, the steel sheet was put into a gas nitrocarburizing furnace (Fujikoshi Co., Ltd., EQ-6S) and subjected to soft nitriding treatment at a treatment temperature of 570 ° C. and a holding time at this treatment temperature of 100 minutes. . At this time, 5.0 m ³ / h of ammonia was used as a nitrogen supply source, and 0.05 L / h of methanol was used as a carbon supply source. After completion of the gas soft nitriding treatment, the steel sheet was cooled to room temperature, and the surface roughness was measured with a surface roughness measuring machine. As a result, the arithmetic average roughness Ra was 1.5 μm on average, and the ten-point average roughness Rz Was 10.2 μm.

  Next, 40 mg of powder-based adhesive (Sumitomo Bakelite, Sumilite Resin) is uniformly applied to one section (12.5 mm × 25 mm) of this steel sheet, and the mating steel sheet is overlaid on this coated surface. , 200 ° C. and 1 MPa for 30 minutes.

  In order to evaluate the adhesive strength at room temperature (18 ° C. to 28 ° C.) for the sample thus obtained, a precision universal testing machine autograph (manufactured by Shimadzu Corporation, AG-25TB) is used, A tensile test was conducted at a tensile speed of 10 mm / min. Moreover, in order to evaluate the adhesive strength at the time of heating to 250 degreeC, the sample obtained similarly was heated and the tension test was done. The results are shown in Table 2.

(Examples 1-2 to 1-5)
A sample was obtained in the same manner as in Example 1-1 except that the surface of the steel plate was treated by the method and conditions shown in Table 1. A tensile test was performed on these samples in the same manner as in Example 1-1, and the adhesive strength at normal temperature and 250 ° C. was evaluated. These results are shown in Table 2.

(Examples 1-2 to 1-7)
A sample was obtained in the same manner as in Example 1-1 except that the surface of the steel plate was treated by the method and conditions shown in Table 1. A tensile test was performed on these samples in the same manner as in Example 1-1, and the adhesive strength at normal temperature and 250 ° C. was evaluated. These results are shown in Table 2.

(Example 1-8)
A sample was obtained in the same manner as in Example 1-4, except that a solvent-based adhesive (manufactured by Cashew Co., Ltd., a phenol epoxy adhesive) was used as the adhesive. A tensile test was performed on this sample in the same manner as in Example 1-1, and the adhesive strength at room temperature and 250 ° C. was evaluated. The results are shown in Table 2.

(Comparative Examples 1-1 to 1-7)
A sample was obtained in the same manner as in Example 1-4 except that the surface of the steel plate was treated by the method and conditions shown in Table 1. A tensile test was performed on this sample in the same manner as in Example 1-1, and the adhesive strength at room temperature and 250 ° C. was evaluated. These results are shown in Table 2.

[Evaluation of adhesive strength and corrosion resistance of brake pads]
Next, a pressure plate material made of SAPH400 having an area of 55 cm ² for the adhesive surface of the friction material is subjected to blasting or gas soft nitriding, and the pressure plate obtained by these treatments is bonded to the surface to be bonded. A brake pad was obtained by adhering a friction material using a powder-based adhesive or a solvent-based adhesive, and a test for evaluating the adhesive strength and corrosion resistance was performed.

(Example 2-1)
(1) Roughening process The pressure plate material is put into a rotating barrel type wet blasting device (Mako Co., Ltd., MSB-S5), and a white alumina grid (grid number: # 60, manufactured by Fuji Seisakusho Co., Ltd.) Wet blasting was performed using a slurry having a concentration of 15% by volume consisting of Fuji Random WA-60) and an alkaline cleaning liquid (Nihon CB Chemical Co., Ltd., Chemicleaner 576). At this time, the air pressure was 0.1 MPa, the treatment time was 180 seconds, the slurry temperature was 30 ° C., and the pH value was 10 (based on a liquid temperature of 25 ° C.). After wet blasting, the surface roughness of the pressure plate was measured with a surface roughness measuring machine. As a result, the arithmetic average roughness Ra was 1.2 μm on the average of the four pressure plates, and the ten-point average roughness Rz. Was 7.9 μm.

(2) Drying and washing | cleaning process After the wet blasting process, the pressure plate was taken out from the rotating barrel type wet blasting apparatus, and 30 degreeC compressed air was sprayed immediately, and the surface was dried. Furthermore, using a hydrocarbon-based cleaning solution (AY Clean A-78L, manufactured by Nippon Grease Co., Ltd.), the pressure plate was cleaned by immersing it under reduced pressure to completely remove moisture remaining on the surface. At this time, as a result of observing a cross section near the surface of the pressure plate with a scanning electron microscope and an X-ray diffractometer (manufactured by Shimadzu Corporation, XRD-6100), it was confirmed that there was no oxide film on the surface. It was.

(3) Heat treatment step Immediately after the drying and washing steps, the pressure plate is put into a gas soft nitriding furnace (Fujikoshi Co., Ltd., EQ-6S), the treatment temperature is 570 ° C., and the holding time at this treatment temperature is 100 minutes. Soft nitriding was performed. At this time, 5.0 m ³ / h of ammonia was used as a nitrogen supply source, and 0.05 L / h of methanol was used as a carbon supply source. After completion of the gas soft nitriding treatment, the pressure plate was cooled to 60 ° C. or less, and the surface roughness was measured with a surface roughness measuring machine. As a result, the arithmetic average roughness Ra was 1.5 μm, and the ten-point average roughness Rz was It was 10.1 μm.

  The pressure plate thus subjected to the gas soft nitriding treatment was cut in the thickness direction, the cross section was treated with a nital liquid, and the cross section was observed with an optical microscope. As a result, the thickness of the nitrogen diffusion layer was 300 μm. It was confirmed that the thickness of the nitrogen compound layer was 23 μm and the thickness of the porous layer was 14 μm.

  Table 4 shows the surface properties (surface roughness, thickness of each layer) of the pressure plate obtained by these treatments. Moreover, the cross-sectional SEM image of the pressure plate at this time is shown in FIG.

(4) Adhesion process A mixture composed of a fiber base material, a binder, a filler, a lubricant, and the like is subjected to pressure molding at room temperature at 20 MPa for 10 seconds to obtain a molded product (preliminary molded body) composed of these mixtures. It was. On the other hand, among the surfaces of the three pressure plates obtained in the same manner as described above, the phenol resin powder adhesive A (Sumilite Resin, manufactured by Sumitomo Bakelite Co., Ltd.) was adhered to the adherend surface to which the preform was bonded. ) Was applied. Thereafter, the preformed body was set on a thermoforming mold in a state where the preformed body was superimposed on the adherend surface of the pressure plate, and subjected to heat and pressure molding at 150 ° C. and 40 MPa for 5 minutes to bond the pressure plate and the preformed body.

(6) Finishing process The pressure plate to which the preform was bonded was heat-treated at 250 ° C. for 3 hours, and then finished to obtain a brake pad.

(7) Evaluation test Using the three brake pads obtained as described above, (a) adhesive strength at room temperature, (b) adhesive strength when heated to 300 ° C, and (c) corrosion resistance were evaluated. It was.

(A) Bond strength at normal temperature Using a precision universal testing machine Autograph (manufactured by Shimadzu Corporation, AG-25TB), a shear test (JIS D4422) is performed on the brake pad, and a pressure plate at normal temperature (25 ° C) The adhesive strength (average value, minimum value, and maximum value) of the friction material was measured. Further, the remaining ratio of the friction material remaining on the pressure plate after shearing (= the area of the remaining friction material / the area of the adherend surface) was determined, and the one with the remaining ratio of 100% was defined as “good (◯)”. Those with 80% or more and less than 100% were evaluated as “possible (Δ)”, and those with less than 80% were evaluated as “bad” (x).

(B) Adhesive strength at 300 ° C. Except that the brake pad was heated to 300 ° C., a shear test was performed in the same manner as in (a) to measure the adhesive strength between the pressure plate and the friction material at 300 ° C. Was evaluated.

(C) Corrosion resistance Five cycles of spraying 2 mL of 5% by mass of salt water on the surface of the brake pad using a spray spray and allowing to stand in a constant temperature and humidity layer maintained at a temperature of 50 ° C. and a humidity of 90% are performed for 5 cycles. A salt spray test was conducted, and a sample in which no rust was generated on the surface of the pressure plate was evaluated as “good (◯)”, and a sample in which rust was generated was evaluated as “bad” (x). The results of these evaluation tests are shown in Table 5.

(Examples 2-2 to 2-27, Comparative Examples 2-1 to 2-4)
A brake pad was obtained in the same manner as in Example 2-1, except that the surface of the pressure plate was treated by the method and conditions shown in Table 3. About these brake pads, (a) adhesive strength at normal temperature, (b) adhesive strength at 300 ° C., and (c) corrosion resistance were evaluated. Table 4 shows the surface properties (surface roughness, thickness of each layer) of the pressure plate, and Table 5 shows the results of the evaluation test. Moreover, the cross-sectional SEM image of the pressure plate of Comparative Example 2-1 (only gas soft nitriding) and 2-3 (salt bath soft nitriding) is shown in FIG. 2 and FIG.

(Example 2-28)
Using a compressed air drive last device (Shin Nippon Koki Service Co., Ltd., e-blaster), a white alumina grid (grid number: # 60, Fuji Seisakusho, Fuji Random WA-60) The drive plate was subjected to a drive last process with an air pressure of 0.3 MPa and a processing time of 60 seconds. After the drive last treatment, the surface of the pressure plate was washed with an alkali cleaning solution (Nihon CB Chemical Co., Ltd., Chemicleaner 576), sprayed with 30 ° C. compressed air, and dried. Immediately after drying, the pressure plate was washed by immersing it under reduced pressure using a hydrocarbon-based cleaning solution (manufactured by Nippon Grease Co., Ltd., AY Clean A-78L) to completely remove moisture remaining on the surface. At this time, as a result of observing a cross section near the surface of the pressure plate with a scanning electron microscope and an X-ray diffractometer, it was confirmed that no oxide film was present on the surface.

  After the drying and washing steps, a brake pad was obtained in the same manner as in Example 2-1. About these brake pads, (a) adhesive strength at normal temperature, (b) adhesive strength at 300 ° C., and (c) corrosion resistance were evaluated. Table 4 shows the surface properties (surface roughness, thickness of each layer) of the pressure plate, and Table 5 shows the results of the evaluation test.

(Examples 2-29 to 2-34)
The roughening treatment step was the same as in Example 2-1, except that a flat wet blast apparatus (manufactured by Macau Corporation, Cocot) was used and the surface of the pressure plate was treated by the method and conditions shown in Table 3. The brake pad was obtained. About these brake pads, (a) adhesive strength at normal temperature, (b) adhesive strength at 300 ° C., and (c) corrosion resistance were evaluated. Table 4 shows the surface properties (surface roughness, thickness of each layer) of the pressure plate, and Table 5 shows the results of the evaluation test.

(Examples 2-35 to 2-38)
Brake pads were obtained in the same manner as in Example 2-15 except that the adhesives shown in Tables 6 and 7 were used. About these brake pads, (a) adhesive strength at normal temperature, (b) adhesive strength at 300 ° C., and (c) corrosion resistance were evaluated. Table 7 shows the results of these evaluation tests.

(Comparative Example 2-5)
Brake pads were obtained in the same manner as Comparative Example 2-1, except that the adhesives shown in Tables 6 and 7 were used. About this brake pad, (a) adhesive strength in normal temperature, (b) adhesive strength in 300 degreeC, and (c) corrosion resistance were evaluated, respectively. Table 7 shows the results of these evaluation tests.

(Comparative Example 2-6)
Brake pads were obtained in the same manner as in Comparative Example 2-2 except that the adhesives shown in Tables 6 and 7 were used. About this brake pad, (a) adhesive strength in normal temperature, (b) adhesive strength in 300 degreeC, and (c) corrosion resistance were evaluated, respectively. Table 7 shows the results of these evaluation tests.

(Comparative Example 2-7)
Brake pads were obtained in the same manner as Comparative Example 2-3 except that the adhesives shown in Tables 6 and 7 were used. About this brake pad, (a) adhesive strength in normal temperature, (b) adhesive strength in 300 degreeC, and (c) corrosion resistance were evaluated, respectively. Table 7 shows the results of these evaluation tests.

1 Brake pad 2 Pressure plate 3 Friction material

Claims (14)

A method for producing a pressure plate made of ferrous metal, comprising a surface to be bonded to which a friction material is bonded,
A roughening step of roughening at least the adherend surface of the pressure plate by blasting and removing an oxide film present on the adherend surface;
Later than the roughening step, a drying step of performing a vacuum dry, compressed air drying or hot air drying,
After the drying step, a finish cleaning step of cleaning with a hydrocarbon-based cleaning liquid ;
After pre Symbol finish washing step, or before the oxide film before Symbol adherend surface is formed again, or, in a state of less than 1μm be formed, a heat treatment step of the pressure plate for processing gas soft When,
A method of manufacturing a pressure plate. The pressure plate manufacturing method according to claim 1, wherein wet blasting is used as the blasting process. The drive blast is used as the blast treatment, and a cleaning step of cleaning with tap water or an alkaline aqueous solution is provided after the roughening step and before the drying step. Pressure plate manufacturing method. The arithmetic average roughness Ra of the adherend surface of the pressure plate after the heat treatment step is in the range of 1.5 μm to 8.0 μm, and the ten-point average roughness Rz is in the range of 10 μm to 40 μm. The manufacturing method of the pressure plate in any one of -3. The pressure plate manufacturing method according to any one of claims 1 to 4 , wherein a difference in height between the most protruding portion and the most recessed portion of the adherend surface is set to 5 µm to 50 µm. In the blast treatment, a grid having a particle size in the range of # 24 to # 100 is used as an abrasive, the air pressure is in the range of 0.1 MPa to 0.5 MPa, and the treatment time is in the range of 10 seconds to 600 seconds. setting method of the pressure plate according to any one of claims 1-5. The method for producing a pressure plate according to claim 6 , wherein at least one selected from white alumina, brown alumina, black silicon carbide, and green silicon carbide is used as the grid. The method for manufacturing a pressure plate according to claim 6 or 7 , wherein wet blasting is used as the blasting treatment, and the grid concentration of the grid is 5 mass% to 30 mass%. In the gas soft nitriding treatment, a mixed gas atmosphere composed of ammonia gas and carburizing gas is used, the treatment temperature is set in the range of 500 ° C. to 590 ° C., and the treatment time is set in the range of 0.1 hour to 4 hours. The manufacturing method of the pressure plate in any one of Claims 1-8 . A method for manufacturing a brake pad, comprising: attaching a friction material to an adherend surface of a pressure plate obtained by the manufacturing method according to any one of claims 1 to 9 via an adhesive. An iron-based metal base material, a surface to be bonded to the friction material of the base material , and nitrogen that is formed on at least the surface to be bonded among the surfaces of the base material and does not contain a halogen element A diffusion layer, and a nitrogen compound formed on the nitrogen diffusion layer and having an arithmetic average roughness Ra in the range of 1.5 μm to 8.0 μm and a ten-point average roughness Rz in the range of 10 μm to 40 μm A pressure plate comprising a layer and a porous layer formed on the outermost part of the nitrogen compound layer and having a thickness in the range of 3.0 μm to 20.0 μm. The pressure plate according to claim 11 , wherein the nitrogen compound layer has a thickness of 5 μm to 25 μm. The pressure plate according to claim 12 , wherein a difference in height between the most protruding portion and the most recessed portion of the nitrogen compound is 5 μm to 50 μm. A brake pad comprising the pressure plate according to any one of claims 11 to 13 , and a friction material bonded to an adherend surface of the pressure plate via an adhesive.