KR100674117B1 - Friction brake apparatus using functionally graded materials - Google Patents

Abstract

A friction brake apparatus using a functionally gradient material(FGM) is provided to reduce thermal deformation by using the FGM and improve mechanical property. A friction brake apparatus using a functionally gradient material(FGM), comprises a rotation member, a friction member, and an operation unit. The rotation member performs rotational motion. The friction member attenuates the rotational motion by applying a frictional force to the rotation member, in contact with at least a part of the rotation member. The operation unit presses the friction member against a surface of the rotation member. A coating layer(120) constituted by the FGM is formed on part of the surface of the rotation member contacting the friction member. The FGM is formed by mixing the material of the rotation member with ceramic. Property of the FGM substantially continually changes from an inner surface to the outer surface of the coating layer contacting the rotation member.

Description

Friction brake device with inclined functional material {FRICTION BRAKE APPARATUS USING FUNCTIONALLY GRADED MATERIALS}

1 is a view schematically showing a structure of a disc brake applied to a vehicle;

2 shows a geometrical model for analyzing the behavior of a friction brake device according to the invention,

FIG. 3 shows hot spots appearing in one frictional drive on the surface of the center stator of the vehicle clutch; FIG.

4 is a graph showing the elastic distribution of the coating layer made of the inclined functional material in the friction brake device having the geometrical model shown in FIG. 3;

5 is a graph showing the relationship between the wave number and the dimensionless critical velocity when the heterogeneity coefficient of the gradient functional material varies;

6 is a graph showing the relationship between the heterogeneity coefficient of the warp functional material and the dimensionless critical velocity when the wave number is different;

7 is a graph showing changes in pressure and temperature at the contact surface between the brake pad and the disc when the brake disc is made of steel;

8 is a graph showing changes in pressure and temperature at the contact surface between the disc and the brake pad when the brake disc has a coating layer made of the inclined functional material;

FIG. 9 shows a change in von Mises stress at the contact surface between the brake pad and the disc when the brake disc is made of steel, and FIG.

FIG. 10 shows the change in von Mises stress at the contact surface between the disc and the brake pad when the brake disc is provided with a coating layer of warp functional material. FIG.

The present invention relates to a friction brake device, and more particularly, to the application of the inclined functional material to reduce the thermoelastic deformation caused by frictional heat in a friction brake device or an electric clutch applied to a vehicle or the like.

Friction brake devices used in vehicles, etc. perform the basic function of ensuring the safety of the occupants. Recently, research has been focused on the improvement of the braking function of the brakes and the reduction of the noise and vibration to improve the ride comfort of the occupants.

Heat is generated by friction during braking of the friction type brake or during operation of the electric clutch. The frictional heat causes thermoelastic deformation in the brake disc or brake drum, which in turn affects the contact pressure distribution. As the sliding speed increases, the contact pressure changes more, and the load is applied locally and the heat generation is concentrated in part. This phenomenon is called thermoelastic instability.

Thermoelastic instability is known to cause hot spots and hot judder in friction clutches and brakes. Local heat generation phenomena as described above create a high stress in the portion, thereby deteriorating the material and eventually destroying it.

In this regard, Korean Patent Application No. 10-2002-0022672 discloses an assembly of an automobile drum brake having a structure for cooling frictional heat by using outside air. Here, a plurality of friction heat discharge portions are formed at equal intervals along the outer circumferential surface of the brake drum, so that high temperature friction heat generated during braking is cooled by the friction heat discharge portion having an enlarged surface area. As a result, the thermal deformation of the brake drum is prevented and the judder generated during braking is also reduced. However, since thermoelastic instability, which is the cause of judder, may occur even with a slight heat generation, the judder prevention effect may be insignificant compared to the effort due to the structural change.

Korean Patent Application No. 10-2002-0069712 provides a mechanism for pressing the brake disc from the inside as well as the outside of the brake disc during braking. This structure is intended to minimize the thermal deformation of the brake disc and to provide a stable braking action. However, the generation of hot spots that cause judder is caused by irregular pressure changes, and only pressing the inner and outer sides of the disk does not make the contact pressure uniform. That is, when the pressure change is small, the structure proposed in the above document can be effectively applied, but the effect is uncertain when the pressure change is large, such as in Juder.

Korean Patent Application No. 10-2000-0081265 discloses a brake judging device for an anti-lock brake system (ABS) for a vehicle. In this device, a vibration sensor is attached to the caliper of each wheel to measure vibration, and when a phenomenon that is judged as judder occurs during braking, the solenoid valve of the wheel part is opened and closed so that the disc and the pad are dropped to prevent judder from occurring. However, safety problems may occur if the disc and the pad are dropped when judging occurs and the brakes need to be continued.

Korean Patent Application No. 10-2000-0065587 proposes a brake pad of a vehicle using an alloy having a different thermal expansion coefficient. Here, a deformation counterpart consisting of a small expansion alloy and a large expansion alloy having different thermal expansion coefficients is provided between the pad plate connected to the piston of the wheel cylinder and the pad rubbing against the brake disk. When the brake disc is thermally deformed by frictional heat, the device is intended to prevent the occurrence of judder by causing the frictional action to occur stably while the surface of the pad is in close contact with the brake disc by the expansion action of the deformation counterpart. . However, the joining of two materials with different material constants results in severe thermal stresses and temperature differences at the interface of the two materials. In addition, the interface may be destroyed by high residual stress and thermal fatigue load.

In view of the above problems, an object of the present invention is to provide a friction brake device having excellent mechanical properties while reducing thermal deformation by using a functionally graded material (FGM), which is one of the composite materials.

In order to achieve the above object of the present invention, a friction type brake device comprising: a rotating member for rotating motion; A friction member in contact with at least a portion of the surface of the rotating member to attenuate the rotational motion by applying a friction force to the rotating member; And an operation unit for pressing the friction member against the surface of the rotating member, wherein the partial surface of the rotating member in contact with the friction member is provided with a coating layer made of an inclined functional material.

In addition, the inclined functional material forming the coating layer of the rotating member is preferably a material in which the material constituting the rotating member and the ceramic material are mixed.

The physical properties of the inclined functional material forming the coating layer of the rotating member vary substantially continuously from the inner surface of the coating layer in contact with the surface of the rotating member toward the outer surface of the coating layer, and on the outer surface of the coating layer the same as that of the ceramic material. It may have physical properties and the same physical properties as the material of the rotating member on the inner surface of the coating layer.

More specifically, the physical properties of the coating layer of the rotating member is as follows, that is,

P = Ps + (Ps-Pc) ((ty) / t) ^α , t <y <2t

Will change accordingly. Here, P denotes the physical properties of the gradient functional material forming the coating layer, Ps denotes the physical properties of the material forming the rotating member, Pc denotes the physical properties of the ceramic material, α denotes the heterogeneous coefficient of the gradient functional material, and t denotes the thickness of the coating layer. In addition, y = t is the position of the inner surface of the coating layer in contact with the surface of the rotating member, y = 2t represents the position of the outer surface of the coating layer.

In the above formula, it is preferable that the inhomogeneity coefficient α of the warp function material is larger than 1, preferably, α is set in the range of 4 to 7, and more preferably, the inhomogeneity coefficient α of the warp function material is about 6 to be.

Meanwhile, the material constituting the rotating member may be a metal material, for example, steel.

Such a friction brake device according to the present invention can be applied to a vehicular drum brake or a vehicular disk brake.

According to another aspect of the present invention, there is provided a rotating member, which includes a rotating member made of an inclined function material; A friction member in contact with at least a portion of the surface of the rotating member to attenuate its rotational motion by applying a frictional force to the rotating member; And an actuating unit for pressing the friction member against the surface of the member making the rotational movement.

The inclined functional material forming the rotating member is preferably a material in which a metal material and a ceramic material are mixed.

Preferably, the physical properties of the inclined functional material forming the rotating member change substantially continuously from the center of the rotating member toward the outer surface of the rotating member, and the outer surface of the rotating member has the same physical properties as the ceramic material. It has the same physical properties as the metal material at the center of the rotating member.

The physical properties of the warp functional material forming the rotating member may vary according to the following equation:

P = Pm + (Pm-Pc) ((ty) / t) ^α , t <y <2t

Where P is the physical property of the inclined functional material constituting the rotating member, Pm is the physical property of the metal material, Pc is the physical property of the ceramic material, α is the heterogeneous coefficient of the inclined functional material, and t is the thickness of the coating layer. In addition, y = t denotes the center of the rotating member, and y = 2t denotes the position of the outer surface of the rotating member.

The inhomogeneity coefficient α of the warp function material is preferably greater than 1, preferably, the inhomogeneity coefficient of the warp function material is determined in the range of 4 to 7, more preferably, the inhomogeneity coefficient of the warp function material α is about 6.

The metal material constituting the rotating member is preferably steel.

According to another aspect of the invention, the rotation member made of a metal material and the rotational movement; A friction member made of an inclined functional material comprising a metal material and a ceramic material, the friction member in contact with at least a portion of the surface of the rotation member to attenuate its rotational motion by applying a friction force to the rotation member; And an actuating unit for pressing the friction member against the surface of the member making the rotational movement.

Here, it is preferable that the physical properties of the warp functional material forming the friction member change substantially continuously from the center of the friction member toward the outer surface of the friction member.

According to still another aspect of the present invention, there is provided a rotating member comprising a metal material and performing a rotational movement; A friction member in contact with at least a portion of the surface of the rotating member to attenuate the rotational motion by applying a friction force to the rotating member; And an operation unit that presses the friction member against the surface of the rotational member, wherein a frictional brake device is provided on the surface of the friction member provided with a coating layer made of an inclined functional material.

Here, the inclined functional material forming the coating layer of the friction member is preferably a material in which a metal material and a ceramic material are mixed.

Preferably, the physical properties of the warp functional material forming the coating layer of the friction member vary substantially continuously from the inner surface of the coating layer in contact with the surface of the rotating member toward the outer surface of the coating layer, wherein the ceramic material on the outer surface of the coating layer It has the same physical properties as that of and has the same physical properties as the metal material on the inner surface of the coating layer.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

1 is a view schematically showing a structure of a caliper disc brake applied to a vehicle.

Generally, a disc brake includes a disc 10 attached to a wheel of a vehicle, a brake pad 20 provided on both sides of the disc, a piston 30 connected to the brake pad 20, and a hydraulic system for operating the piston 30 ( 40). The disk 10 is connected to the wheel of the vehicle and makes a rotational movement while the vehicle is in progress. When the occupant presses the brake pedal, the hydraulic system 40 operates to operate the piston 30, and the brake pad 20 attached to the front end of the piston generates friction force by contacting the disk 10 to rotate the disk. Braking the movement. Accordingly, braking is applied to the rotational movement of the wheel, and the moving speed of the vehicle is reduced or stopped. In the brake device for a vehicle, the disk 10 is mainly made of steel, and the brake pad 20 is made of friction material.

In the disc brake according to the present invention, a coating layer (not shown) made of an inclined functional material is provided on the surface of the disc 10 in contact with the brake pad 20. In the embodiment according to the invention the disc 10 is made of steel and the warp functional material is made of a composite material of steel and ceramic. The Applicant has studied the phenomenon related to thermoelastic instability appearing in the brake device when the disk has a coating layer made of the inclined functional material. Hereinafter, an analysis process and a result of the disc brake device having the coating layer made of the inclined functional material will be described.

Figure 2 shows a geometric model adopted by the applicant for analyzing the behavior of a friction brake device having a structure according to the invention.

In this geometric model, the two outer layers 200 representing the friction pads move at a relative sliding speed V in the horizontal direction with respect to the intermediate layer 100 representing the disk. The outer layer 200 is made of a friction material, and the intermediate layer 100 has a core portion 110 made of steel and a coating layer 120 made of an inclined functional material. The coating layer 120 is provided on the surface in contact with the outer layer 200. The thickness of the outer layer 200 is each h. The intermediate layer 100 has a thickness of 2a of the core part 110, a thickness of the coating layer 120 made of an inclined functional material is 2t, and the thickness of the entire intermediate layer 100 is 2a + 2t. This model is geometrically symmetric about the y = h + a + t axis. In this embodiment, the case where the thickness t of the coating layer 120 has a thickness of 10% with respect to the thickness 2a of the core part 110 is examined. On the other hand, since the model examined in this embodiment is geometrically symmetrical with respect to the disc brake device provided on both sides of the coating surface, when applied in a case where it is not symmetrical, such as a drum brake, the examination in this embodiment is carried out on the coating layer 120. It can be seen that the thickness can be applied when the thickness of 20% of the core portion 110.

The thermoelastic phenomenon is assumed to be periodic symmetry with a wavelength of L = C / m with respect to the sliding direction x. Where C is the outer circumference of the disk and m is the wavenumber, ie the number of wavelengths along the circumference. Even in a real friction system, the phenomenon due to thermoelastic instability usually occurs periodically. 3 shows the hot spots that appear after the central stator surface of the automobile clutch has undergone one frictional drive. The dark areas on the surface of the stator are areas (hot spots) that have undergone local high temperature heat. As can be seen from FIG. 3, thermoelastic instability due to friction is generally periodic.

As described above, in the model shown in FIG. 2, the outer layer 200 is mainly made of a friction material. In the intermediate layer 100, the core part 110 is made of steel, and the coating layer 120 is formed of a combination of steel and ceramics. Made of inclined functional material. Table 1 shows the physical properties of each material applied by the applicant in the analysis.

Friction material Core material (steel) Ceramic material Elastic Modulus 0.3 200 151 Thermal Expansion 1.4 1.2 1.0 Thermal Conductivity 0.09 42 2.2 Poisson's Ratio 0.12 0.3 0.3 Thermal Diffusivity 4.167 11.91 0.623

The friction material and the steel of the core portion have uniform properties over the entire volume, and the warp function material changes in properties as the height changes in that region. The mixing ratio of the two materials forming the warp functional material in the coating layer is to be changed continuously with the height, so the physical properties also change continuously. That is, the physical property is a function of the height and the change in the physical properties of the coating layer on top in FIG. 2 can be given by the following equation:

Here, P, Ps and Pc are properties of the warp function material, steel and ceramic, respectively. α is the heterogeneous coefficient of the gradient functional material. Equation 1 can be applied to modulus of elasticity, thermal expansion, thermal conductivity, and thermal diffusion. In FIG. 2, the change in the physical properties of the lower coating layer is symmetrical to the change in the physical properties of the upper coating layer.

As can be seen from Equation 1, the physical properties of the coating layer 120 made of the inclined functional material is the same as the physical properties of the steel at the interface between the core portion 110 and the coating layer 120 and gradually changes depending on the height of the ceramic on the outer surface. Becomes the same as Physical properties in the coating layer 120 is determined by the constant α. FIG. 4 illustrates changes in the elastic modulus and thermal conductivity of the coating layer 120 in the case where α has three values. As shown, in the case of α = 1, the physical properties of the inclined functional material in the coating layer 120 change linearly. In the case of α> 1, it means that the content of ceramic is relatively high in the inclined functional material forming the coating layer 120 (indicated by “ceramic FGM” in FIG. 4), and in the case of 0 <α <1, the content of steel This relatively much means (in FIG. 4 it is labeled “metal FGM”).

5 shows the relationship between the wave number and the dimensionless critical velocity when the inhomogeneity coefficient α of the warp functional material is changed.

In the present invention, the term critical speed is used in the following sense: In a system in which two surfaces rotate or slide in contact with each other, such as a brake or clutch, the non-uniform temperature of the contact surface by frictional heat at a certain speed. And hot elastic deformation increase, causing local heat generation and pressure concentration, and hot spots grow. The speed at this time is called the critical velocity. Thus, a large critical speed means that the thermal stability of the corresponding brake system is high. Theoretical background for this is J. R. Barber, “Themoelastic instability in the sliding of conforming solids”, Proc. R. Soc. London, Ser. A. 312, pp. 381-394, first presented in 1969, and recently in K. Lee and R. B. Dinwiddie's “Conditions of frictional contact in disk brakes and their effects on brake judder”, SAE paper 980598, 1998.

In FIG. 5, the case where the content of the ceramic is large in the gradient functional material forming the coating layer 120, that is, the case where the heterogeneity coefficient α is larger than 1 is mainly illustrated. For the sake of contrast, if the interlayer 100 consists entirely of steel (Lee &Barber'ssolution; K. Lee and JR Barber “Frictionally Excited Thermoelastic Instability in Automotive Disk Brakes”, Journal of Tribology, Vol. 115, pp. 605 -614, 1993). As can be seen from FIG. 5, in the case where the coating layer 120 is present, the dimensionless critical speed, V _cr ^* is increased, as compared with the case where the intermediate layer 100 is all made of steel. Specifically, the critical velocity increases as the heterogeneity coefficient α increases from 1, has a maximum when α is approximately 6, and decreases again when α is greater than 6. This phenomenon is more clearly shown in Fig. 6 which shows the relationship between the heterogeneity coefficient and the dimensionless critical velocity when the wave number changes.

As can be seen from the foregoing, when the intermediate layer 100 is provided with a coating layer 120 made of the inclined functional material, the variation due to thermoelastic instability is suppressed as compared with the prior art in which the intermediate layer 100 is made of steel only.

In order to specifically confirm the operation of the brake device according to the present invention, the pressure and temperature changes during the braking operation were examined. 7 and 8 illustrate pressure and temperature changes over time at the contact surface between the outer layer 200 and the intermediate layer 100. 7 is a case where all the intermediate layer 100 is made of steel as in the prior art, and FIG. 8 is a case where the coating layer 120 made of the inclined functional material is provided in the intermediate layer 100 according to the present invention.

According to the prior art, when t = 0.04 s has elapsed, the pressure difference, which was initially small, rapidly increases, and contact separation occurs. In the area where contact separation occurs, the temperature varies discontinuously at the interface between the outer layer 200 made of friction material and the intermediate layer 100 made of steel, and the temperature of the outer layer 200 appears higher. In addition, the temperature rises sharply locally to promote contact separation.

In contrast, in the case of providing the coating layer 110 made of the inclined functional material according to the present invention, contact separation does not occur. In addition, although the average temperature is high, it can be seen that the temperature difference does not increase in the contact area between the intermediate layer 100 and the outer layer 200. Therefore, it can be seen that the coating layer 110 made of the inclined functional material reduces the local temperature difference and raises the average temperature in the contact region. Since the occurrence of local temperature difference is one of the main factors causing thermoelastic instability, when the intermediate layer 100 has the coating layer 110 made of the inclined functional material according to the present invention, the thermoelastic instability is suppressed and the critical velocity is increased. Is increased.

9 and 10 show thermoelastic stress changes in the case according to the prior art and in the case according to the invention, respectively.

As in the prior art, when the intermediate layer 100 is made of steel only, the temperature rises locally and the temperature difference also increases. Accordingly, when contact separation occurs, the stress locally increases in the hot spot region.

According to the present invention, when the intermediate layer 100 is provided with the coating layer 110 made of the inclined functional material, the stress in the contact region appears high but the change range of the stress is very small. Therefore, when the intermediate layer 100, that is, the disk is provided with the coating layer 110 made of the inclined functional material according to the present invention, even if the brake device is used for a long time, the generation of cracks, buckling, etc. can be maintained and reliability can be maintained. have.

Although the invention has been described in detail based on the embodiments shown in the accompanying drawings, it is apparent that various modifications are possible without departing from the scope of the invention. Nothing described herein is intended to narrow the scope of the invention to the scope of the appended claims. The foregoing examples are for illustrative purposes only and are not intended to exclude those having other embodiments.

For example, in the above, the case in which the inclined function material is used for the disc brake applied to the vehicle as an embodiment according to the present invention has been described. However, the present invention is not limited thereto, and a system using widely friction, for example, It is apparent to those skilled in the art that the present invention can be applied to a stator or the like of a vehicle clutch.

In addition, in the above-described embodiment, only the case where the core part 110 of the intermediate layer 100 is made of steel is described, but the present invention is not limited thereto, and the material of the intermediate layer 100 is provided with appropriate deformation. Any material used in industrially friction-based systems can be used.

Furthermore, in the above-described embodiment, the case where the thickness of the coating layer 120 which is geometrically symmetrical and the inclined functional material is 10% of the thickness of the core portion 110 is described as an example, but the thickness of the coating layer 120 is Can vary. For example, the intermediate layer 100 may not be divided into the core part 110 and the coating layer 120, but may be entirely made of an inclined functional material.

On the other hand, in the above-described embodiment has been described a case in which the rotating member having a rotary motion is provided with a coating layer made of the inclined functional material, on the other hand, the rotating member is made of a metallic material and the friction member is made of a coating made of the inclined functional material It may be provided or the entire friction member may be made of an inclined functional material. For example, the friction member may be made by mixing a ceramic-based fibrous material and a metal-based fibrous material.

According to the present invention, it is possible to provide a friction type brake device having excellent mechanical properties while reducing thermal deformation by using an inclined functional material which is one of the composite materials.

Claims (24)

delete delete A rotating member that rotates; A friction member in contact with at least a portion of the surface of the rotating member to attenuate the rotational motion by applying a friction force to the rotating member; And An actuating unit for pressing the friction member against a surface of the member making the rotational movement, The partial surface of the rotating member in contact with the friction member is provided with a coating layer made of an inclined functional material, and the inclined functional material forming the coating layer of the rotating member is a material in which the material constituting the rotating member and a ceramic material are mixed. , The physical properties of the inclined functional material forming the coating layer of the rotating member is changed substantially continuously from the inner surface of the coating layer in contact with the surface of the rotating member toward the outer surface of the coating layer, and on the outer surface of the coating layer Friction brake device having the same physical properties and the same physical properties of the material forming the rotating member on the inner surface of the coating layer. The method according to claim 3, Friction brake device, characterized in that the physical properties of the coating layer of the rotating member is changed according to the following equation: P = Ps + (Ps-Pc) ((ty) / t) ^α , t <y <2t Where P is the property of the gradient functional material forming the coating layer, Ps is the property of the material forming the rotating member, Pc is the property of the ceramic material, α is the heterogeneous coefficient of the gradient function material, and t is the thickness of the coating layer, y = t Is the position of the inner surface of the coating layer in contact with the surface of the rotating member, y = 2t indicates the position of the outer surface of the coating layer. The method according to claim 4, Friction brake device, characterized in that the inhomogeneity coefficient α of the inclined functional material is greater than one. The method according to claim 5, Friction brake device, characterized in that the inhomogeneity coefficient α of the inclined functional material is determined in the range of 4 to 7. The method according to claim 6, Friction brake device, characterized in that the inhomogeneity coefficient α of the warp function material is about 6. The method according to claim 3, Friction brake device, characterized in that the material constituting the rotating member is a metal material. The method according to claim 8, Friction brake device, characterized in that the material constituting the rotating member is steel. The method according to claim 3, Friction brake device, characterized in that applied to the vehicle drum brake. The method according to claim 3, Friction brake device, characterized in that applied to the vehicle disk brake. delete delete A rotating member that rotates and is made of an inclined function material; A friction member in contact with at least a portion of the surface of the rotating member to attenuate its rotational motion by applying a frictional force to the rotating member; And An actuating unit for pressing the friction member against a surface of the member making the rotational movement, The inclined functional material forming the rotating member is a material in which a metal material and a ceramic material are mixed, and the physical properties of the inclined functional material forming the rotating member are changed substantially continuously from the center of the rotating member toward the outer surface of the rotating member. And an outer surface of the rotating member having the same physical properties as those of the ceramic material and having the same physical properties as the metallic material at the center of the rotating member. The method according to claim 14, Friction brake device, characterized in that the physical properties of the inclined functional material forming the rotating member is changed according to the following equation: P = Pm + (Pm-Pc) ((ty) / t) ^α , t <y <2t Where P is the property of the inclined functional material constituting the rotating member, Pm is the physical property of the metal material, Pc is the physical property of the ceramic material, α is the heterogeneous coefficient of the inclined functional material, and t is the thickness of the coating layer, y = t Is the center of the rotating member, y = 2t indicates the position of the outer surface of the rotating member. The method according to claim 15, Friction brake device, characterized in that the inhomogeneity coefficient α of the inclined functional material is greater than one. The method according to claim 16, Friction brake device, characterized in that the inhomogeneity coefficient α of the inclined functional material is determined in the range of 4 to 7. The method according to claim 17, Friction brake device, characterized in that the inhomogeneity coefficient α of the warp function material is about 6. The method according to claim 14, And the metallic material constituting the rotating member is steel. delete A rotating member made of a metal material and configured to rotate; A friction member made of an inclined functional material comprising a metal material and a ceramic material, the friction member in contact with at least a portion of the surface of the rotation member to attenuate its rotational motion by applying a friction force to the rotation member; And An actuating unit for pressing the friction member against a surface of the member making the rotational movement, And physical property of the warp functional material forming the friction member is substantially continuously changed from the center of the friction member toward the outer surface of the friction member. delete delete A rotating member made of a metal material and configured to rotate; A friction member in contact with at least a portion of the surface of the rotating member to attenuate the rotational motion by applying a friction force to the rotating member; And An actuating unit for pressing the friction member against a surface of the member making the rotational movement, The surface of the friction member is provided with a coating layer made of an inclined functional material, the inclined functional material forming the coating layer of the friction member is a material in which a metal material and a ceramic material are mixed, and an inclined functional material forming the coating layer of the friction member. The physical properties of the material change substantially continuously from the inner surface of the coating layer in contact with the surface of the rotating member toward the outer surface of the coating layer, the outer surface of the coating layer having the same physical properties as the ceramic material and on the inner surface of the coating layer Friction brake device with the same physical properties as the material.

Images