JP7444549B2 - Overlay layer, sliding bearing equipped with the same, and manufacturing method thereof - Google Patents

Description

The present invention relates to an overlay layer, a plain bearing provided with the same, and a method for manufacturing the same.

Physical vapor deposition is known as a method for forming metal layers, particularly thin metal layers. According to the vacuum evaporation method, which is one of the physical vapor deposition methods, a substrate (on which a metal layer is formed) and a metal pod, which is an evaporation source, are placed in a vacuum chamber, and the evaporation source is heated to evaporate the metal. As a result, the metal is deposited on the surface of the substrate, thereby forming a metal layer.

A thin metal layer (overlay layer) made of Bi or the like is sometimes formed as a surface layer of the bearing. High durability is required for metal layers used under harsh conditions, such as in bearings.
Patent Document 1 discloses an example in which a bearing overlay layer made of a Bi-based material is formed by a wet plating method.
Patent Document 2 shows an example in which an overlay layer made of a Bi-based material formed by a wet plating method is composed of crystals strongly oriented in the (202) plane with Miller index. Such an overlay layer has excellent anti-seizure properties.

Japanese Patent Application Publication No. 2001-20955 Japanese Patent Application Publication No. 2004-308883

From the descriptions in Patent Document 1 and Patent Document 2, it can be seen that the characteristics of an overlay layer made of a Bi-based material are related to the orientation of crystals constituting the overlay layer.
The metal layers described in these patent documents are formed by wet plating, but there are limited methods to control the crystal orientation of the metal layer by wet plating, and it is difficult to improve fatigue resistance and corrosion resistance more than before. It is difficult to do so.

The present inventors have focused on the physical vapor deposition method as a method for forming an overlay layer made of a Bi-based material, and have conducted extensive studies with the objective of controlling the orientation of crystals constituting the overlay layer.
As a result, when physically depositing Bi (including Bi alloys, the same applies hereinafter) onto a substrate, the first amount of heat capable of melting Bi is supplied to the growth surface side where Bi is supplied in the overlay layer being grown, and the overlay layer is A second amount of heat capable of maintaining the opposite surface at a temperature lower than the melting point of Bi is supplied to the opposite surface located opposite to the growth surface in the layer, and a high temperature region is generated on the growth surface side in the overlay layer being grown. It has also been found that by creating a low temperature region lower than the melting point of Bi on the opposite side, it is possible to change the orientation of the crystals constituting the overlay layer.
That is, the overlay layer formed as described above has a different crystal orientation than that of an overlay layer obtained by a general-purpose physical vapor deposition method or a wet plating method.

For example, FIG. 1 shows the orientation ratio of crystals constituting the surface of a standard Bi sample calculated from the example described in Patent Document 1 by X-ray diffraction. The invention of Patent Document 1 attempts to make the overlay layer exhibit excellent sliding characteristics by configuring the overlay layer with a metal material having substantially the same orientation as a standard Bi sample.
Here, the orientation ratio is defined as the peak intensity R = ( It refers to the ratio value (%) of hkl).
Moreover, the crystal orientation refers to the distribution tendency of the orientation rate.

There is a predetermined relationship between the orientation of crystals in a sample and the physical properties of the sample. In other words, by changing the crystal orientation of a sample, its physical properties can be changed.
For example, FIG. 2 shows the orientation ratio of each crystal constituting the surface of a Bi sample based on X-ray diffraction of the Bi sample calculated from the example described in Patent Document 2. The Bi sample of Patent Document 2, which has a crystal orientation different from that in FIG. 1, is substantially strongly oriented in the (202) plane, and thereby exhibits excellent seizure resistance.
A wet plating method is used to manufacture the Bi samples described in Patent Document 1 and Patent Document 2. As described above, the crystal orientation of the Bi sample can be changed using the wet plating method. However, in order to change the crystal orientation, the wet plating conditions must be completely different, and a dedicated wet plating apparatus must be prepared for each.

On the other hand, as explained in the examples, using the same physical vapor deposition apparatus, the first amount of heat is simply supplied to the growth surface side of the overlay layer, and the second amount of heat is supplied to the opposite side of the overlay layer located opposite to the growth surface. By varying the amount of second heat supplied to the side, it was possible to change the crystal orientation of the Bi sample.
FIG. 3 shows the crystal orientation of the Bi sample obtained when the same physical vapor deposition apparatus was used, the vapor deposition source was also the same, and the conditions of the first and second heat quantities were set to the fifth example. FIG. 4 shows the crystal orientation of the Bi sample obtained when the conditions of the first and second heat quantities were set to the twelfth example.

3 and 4, it can be seen that there is a large difference in crystal orientation between the Bi sample obtained in the fifth example and the Bi sample obtained in the twelfth example.
Furthermore, the Bi sample obtained in Example 5 having the orientation shown in FIG. is also new.
The measurement conditions for FIGS. 3 and 4 will be described later.

Incidentally, the following can be said when comparing the Bi sample of Patent Document 1 (FIG. 1), in which peaks appear dispersed in a relatively large number of crystal planes, and the Bi sample of Example 5 (FIG. 3).
In a Bi sample oriented as shown in FIG. 1, there is a high possibility that crystals having the same orientation exist adjacently within the layer (see FIG. 5A). When such a Bi sample is used as a sliding member, cracks tend to propagate in the film thickness direction when a large load (indicated by the arrow line in FIG. 5A) is applied. On the other hand, the Bi sample oriented as shown in FIG. 3 has a lower possibility of crystals having the same orientation existing in close proximity, that is, it has more crystal faces (see FIG. 5B). When such a Bi sample is used as a sliding member, propagation of cracks in the film thickness direction is suppressed when a large load (indicated by the arrow line in FIG. 5B) is applied. In other words, when the Bi sample obtained in Example 5 is used as an overlay layer of a sliding member, the sliding member has excellent fatigue resistance.

Furthermore, the following can be said by comparing the Bi sample of Patent Document 2 (FIG. 2), in which peaks appear concentrated on a relatively small number of crystal planes, and the Bi sample of Example 12 (FIG. 4).
In the Bi sample oriented as shown in FIG. 2, a surface having a large included angle θ with the sliding surface (indicated by thick broken line H in FIG. 6A) appears preferentially (see FIG. 6A). In the figure, a virtual extension of one surface is indicated by a thin broken line I. The edges of these surfaces appearing on the sliding surface H tend to become corrosion starting points (corrosion starting points A) in the sliding environment. When such a Bi sample is used as a sliding surface, the probability of the existence of corrosion starting points A on the sliding surface increases, and as a result, the sliding surface made of the Bi layer becomes more likely to corrode in the sliding environment.
On the other hand, in the Bi sample of Example 12 oriented as shown in FIG. 4, the plane with a small included angle θ appears preferentially (see FIG. 6B). When such a Bi sample is used as a sliding member, the probability of existence of a corrosion starting point A on the sliding surface is smaller than that in the example shown in FIG. 6A, and the corrosion resistance in the sliding environment is improved.

In other words, as proposed by the present invention, a first amount of heat capable of melting Bi is supplied to the growth surface side of the overlay layer being grown by physical vapor deposition, and the opposite surface is supplied to the opposite surface of the overlay layer. When a second amount of heat that can be maintained at a temperature lower than the melting point of It had become a thing. Here, the first amount of heat and the second amount of heat refer to the amount of heat supplied per unit area and per unit time, and the amount of heat in the case of cooling takes a negative value.
Furthermore, by changing the difference between the first amount of heat and the second amount of heat, a change appeared in the orientation.

In order to change the crystal orientation in this way, a first amount of heat capable of melting the Bi is supplied to the growth surface of the overlay layer being grown, and a first amount of heat capable of melting the Bi is supplied to the growth surface of the overlay layer that is being grown, and a first amount of heat capable of melting the Bi is supplied to the growth surface of the overlay layer that is being grown. It is insufficient to simply supply a second amount of heat that can maintain the temperature at a temperature lower than the melting point; therefore, in the overlay layer during growth, there is a high temperature region higher than the melting point of Bi on the growth side, and a lower temperature region lower than the melting point of Bi on the opposite side. It is necessary to generate a low temperature region. In other words, the supply of the first amount of heat and/or the second amount of heat is controlled to create a high temperature region (on the growth side) and a low temperature region (on the opposite side) in the growing overlay layer.

Here, the high-temperature region and the low-temperature region have a size (in the thickness direction of the overlay layer) that exceeds the diameter of crystal grains constituting the overlay layer. Even in the general-purpose physical vapor deposition method, when the overlay layer is in contact with other elements (e.g., a substrate or a substrate holder), a temperature gradient occurs at the contact surface, and physically there are microscopic high-temperature areas and low-temperature areas. is occurring. However, such a microscopic temperature gradient has no effect on crystal orientation. On the other hand, the temperature of crystal grains existing in a low temperature region is considered to affect the orientation of crystals growing thereon. As is clear from a comparison of FIGS. 3 and 4, the crystal orientation changes due to the difference between the first amount of heat and the second amount of heat. By providing a high temperature region and a low temperature region in this way and further adjusting the temperature of the low temperature region, the number of crystal planes in the metal layer is increased. Alternatively, it was possible to reduce the number of crystal grains on a surface with a large included angle with the surface of the overlay layer, and increase the number of crystal grains on a surface with a small included angle than before.

The amount of heat that can melt Bi is supplied as the first amount of heat. As a result, at least the outermost layer of the growth surface is in a liquid phase state. Since a temperature gradient occurs in a deeper portion, it has not been possible to dynamically determine to what extent the liquid phase is present using the applicant's current measurement technology.
However, at least a temperature difference is created between the growth side and the opposite side of the overlay layer.
In other words, in the overlay layer being grown by physical vapor deposition, only the outermost layer is selectively heated to a temperature higher than the melting point of Bi. Here, the outermost layer refers to a layer in a liquid phase on the growth surface side that exists on a layer in a solid phase in the overlay layer.

In order to selectively bring the outermost layer of the overlay layer into a liquid state, a predetermined difference is provided between the first amount of heat applied to the growth surface side of the overlay layer and the second amount of heat applied to the opposite side. It is assumed that when the first amount of heat is supplied, the growth surface of the overlay layer is heated to a temperature higher than the melting point of Bi and is in a liquid phase state. On the other hand, when the second amount of heat is supplied, the opposite surface maintains a temperature at which it does not melt, that is, a temperature at which the crystal is maintained, that is, a solid state is maintained.
This difference in heat amount can be achieved not only by providing a temperature difference between the temperature supplied to the growth side of the overlay layer and the temperature supplied to the opposite side, but also by controlling the amount of heat supplied per hour. For example, heat is supplied intermittently. An example of a method for intermittent heat supply is to irradiate pulses of non-ionizing radiation. By adjusting the pulse width, pulse amplitude, duty cycle, etc., the amount of heat supplied per hour can be controlled. The growth rate of the overlay layer also plays a role in creating the high temperature and low temperature regions.

According to studies by the present inventors, when growing a metal layer by physical vapor deposition, the growth rate is preferably 10 μm to 100 μm/min. A typical physical vapor deposition method that can achieve such a growth rate is a vacuum vapor deposition method.
In the embodiment, infrared rays are uniformly irradiated with pulses over the entire surface of the metal layer on the growth surface side.
The result of controlling the first amount of heat and the second amount of heat appears as a difference between the temperature on the growth side of the workpiece, that is, the metal layer (first temperature), and the temperature on the opposite side (second temperature). .
When comparing the growth side and the opposite side, even if the first temperature and the second temperature are the same, the difference between the first heat amount and the second heat amount causes the difference between the growth side and the opposite side. There may be a difference in the internal temperature distribution between the surface side and the inside temperature distribution. When the first amount of heat is supplied in pulses with non-ionizing radiation, the depth of the high temperature region on the growth surface side can be adjusted by adjusting the pulse width, pulse amplitude, duty cycle, etc.

In order to uniformly irradiate the entire growth surface of the overlay layer with non-ionizing radiation such as infrared rays, at least the Bi source (the evaporation source in the case of vacuum evaporation) should not cast a shadow on the surface irradiated with the non-ionizing radiation. Therefore, the sources of the non-ionizing radiation are arranged so as to sandwich the Bi source. In this case, a reflecting member (mirror, etc.) that reflects non-ionizing radiation also corresponds to a radiation source.
The source of non-ionizing radiation may or may not be located within the vacuum chamber of the physical vapor deposition apparatus. When a source of non-ionizing radiation is installed in a vacuum chamber, the source is placed so as not to create a shadow between the deposition source and the substrate. On the other hand, when the radiation source is placed outside the vacuum chamber, the vacuum chamber is provided with a window that allows the non-ionizing radiation to pass therethrough. These windows are also arranged on both sides of the evaporation source so as to sandwich it.

In the above, general physical vapor deposition methods such as a sputtering method and an ion plating method can be employed in addition to a vacuum vapor deposition method.
Pb, Sn, In, Cu, Ag, Sb, Zn, Al, Ni, Cr, etc. can be added to Bi.
As the non-ionizing radiation that supplies the first amount of heat to the growth surface of the overlay layer, in addition to infrared rays, laser beams, etc., electron beams, X-rays, high frequency waves, microwaves, etc. can be arbitrarily selected depending on the growth conditions.

In order to inexpensively and efficiently raise the temperature of the growth surface of the overlay layer, it is preferable to employ infrared rays. To selectively form a high temperature region on the growth side of the overlay layer, pulsed infrared rays are applied. When infrared rays are used, the wavelength thereof is preferably 0.5 μm to 100 μm, more preferably 0.8 μm to 5 μm.

A second amount of heat delivered to the opposite side of the overlay layer is delivered through the substrate on which the overlay layer is deposited. That is, a temperature control section is provided in the holding section of the substrate, and by controlling the temperature of the substrate, indirectly controls the amount of second heat supplied to the opposite surface. Needless to say, when cooling the substrate side, this amount of heat becomes a negative value.

A dummy sample is used to determine heating conditions that bring the outermost layer of the overlay layer on the growth side into a liquid state and the opposite side into a solid state. This dummy sample imitates an overlay layer, and is detachably attached to a substrate holder of a physical vapor deposition apparatus. Thermometers were attached to the dummy sample on the front surface corresponding to the growth surface side and the back surface corresponding to the opposite surface.

The temperature control section of the substrate holding section is activated to cool the back side of the dummy sample. On the other hand, the surface side of the dummy sample is heated by irradiating infrared rays. While adjusting the cooling function of the temperature control unit and the output of the infrared light source, the surface temperature of the dummy sample (at or above the melting point of Bi) and the back surface temperature of the dummy sample (below the melting point of Bi) were stabilized. The cooling conditions of the temperature control unit and the output conditions of the infrared radiation source (pulse width, pulse amplitude, duty cycle, etc.) are saved. Then, when performing physical vapor deposition of Bi, each condition is reproduced.

As described above, if the conditions in which a difference in temperature between the front and back surfaces occurs in the dummy sample are reproduced, a high temperature region will occur on the growth surface side and a low temperature region will occur on the opposite surface of the overlay layer.
As a result, as shown in FIGS. 3 and 4, the orientation of the crystals constituting the sliding surface of the overlay layer can be changed and controlled.
Therefore, the present inventors conducted various tests based on the above findings. As a result, based on the results shown in FIG. 3, it was found that an overlay layer having the following requirements is preferable from the viewpoint of improving fatigue resistance.

That is, the first aspect of the invention is defined as follows.
It is an overlay layer made of Bi or Bi alloy, and in the X-ray diffraction intensity R = (hkl) measured from the surface, the peak intensity of the (015) plane and the peak intensity of the (107) plane relative to the peak intensity of the (012) plane are The value of the ratio of the total value of peak intensities is 0.9 to 2.5. That is, 0.9≦Equation 1: {R(015)+R(107)}/R(012)≦2.5
On the other hand, when the peak intensity of the Bi overlay layer disclosed in Prior Document 1 is substituted into Equation 1, it is 0.72 (see Table 2: Comparative Example 1 below). In this case, it was 0.65 (Comparative Example 2).

Note that the orientation ratio is the ratio of the peak intensity R=(hkl) of each oriented surface to the sum of the peak intensity R=(hkl) of all oriented surfaces. Therefore,
Equation 1 can be expressed as {orientation rate of (015) plane+orientation rate of (107) plane}/orientation rate of (012) plane.

According to the overlay layer of the first aspect in which the ratio of the orientation ratio of the (107) plane and (015) plane to the orientation ratio of the (012) plane is within a predetermined range, crystals having the same orientation can be formed. The probability that they exist in close proximity is controlled, thereby suppressing the propagation of cracks in the film thickness direction. Therefore, the fatigue resistance of the overlay layer and thus the plain bearing is improved.

Here, if the value of Equation 1 is less than 0.9, the proportion of the (012) plane will increase, and the probability that crystals having the same orientation will exist close to the sliding surface will increase. Therefore, propagation of cracks is promoted.
On the other hand, if the value of Equation 1 exceeds 2.5, the proportion of (107) and (015) planes will become too high, and crystals with the same orientation will exist in close proximity to the sliding surface. In this case, the propagation of cracks in the film thickness direction is also promoted. This causes a decrease in the fatigue resistance of the overlay layer and thus of the plain bearing.

The second aspect of the invention is defined as follows. That is, in the overlay layer specified in the first aspect, the ratio of the peak intensity R3 of the surface having the third largest peak intensity to the peak intensity Rmax of the surface having the maximum intensity is 0.4 or more.
In other words, the value of the ratio of the orientation ratio of the surface having the third strongest orientation ratio to the orientation ratio of the surface having the maximum orientation ratio is 0.4 or more.The overlay of the second aspect defined in this way According to the layer, among the crystals constituting the layer, those having the crystal plane showing the maximum orientation rate and those having the crystal planes showing the second and third largest orientation rates are oriented at approximately the same ratio. In other words, the closer this value is to 1, the less the crystal planes of the crystal grains constituting the overlay layer are biased in a particular direction, and the more likely there are crystals with the same orientation in the metal layer on the sliding surface. less likely to exist in close proximity. Therefore, fatigue resistance is further improved.

The operation of the invention defined in the first and second aspects is schematically shown in FIG.
As shown in FIG. 5A, when the orientation ratio is highly biased toward a specific crystal plane, there is a high probability that crystals having the same orientation exist in close proximity. However, as defined in the first and second aspects of the present invention, if the bias in the orientation rate towards a specific crystal plane is small, the probability that crystals with the same orientation will exist in close proximity is low; As shown in FIG. 5B, since crack propagation occurs between crystals having different orientations, crack propagation in the film thickness direction is inhibited. This improves fatigue resistance.

Moreover, based on the results shown in FIG. 4, it was found that the corrosion resistance of the overlay layer having the following requirements was improved.
That is, the third aspect of the invention is defined as follows.
An overlay layer made of Bi or Bi alloy, in which the X-ray diffraction intensity R = (hkl) measured from the surface of the overlay layer is any of the (104) plane, (015) plane, and (107) plane. The strength of the three surfaces shall be the maximum, and the total strength of these three surfaces shall be 70% or more of the total strength of the entire surface.
In other words, the orientation ratio of any one of the (104) plane, (015) plane, and (107) plane is the maximum, and the total orientation ratio of these three planes is 70% or more.
The total orientation ratio here is the ratio of the sum of orientation ratios of the (104) plane, (015) plane, and (107) plane to the total orientation ratio of each crystal constituting the overlay layer.

According to the overlay layer defined in the third aspect as defined above, all or at least one of the (104) plane, (015) plane, and (107) plane is strongly oriented on the surface thereof. The high orientation ratio of these planes indicates that many of the crystal planes of the crystals constituting the sliding surface are in a direction close to parallel to the sliding surface.
On the other hand, in the overlay layer shown in Patent Document 2, the orientation rate of the (202) plane is high, which indicates that many of the crystal planes of the crystals constituting the sliding surface tend to be close to perpendicular to the sliding surface. ing. Comparing the two, in the overlay layer specified in the third aspect, the probability of the existence of corrosion starting points becomes smaller.

FIG. 7 shows an overlay layer (FIG. 7(A)) of a conventional example (see Patent Document 2) in which the (202) plane is strongly oriented and an overlay layer defined by the third aspect (FIG. 7(B)). The crystal structure of is shown schematically.
From FIG. 7, it can be seen that the crystal structure defined in the third aspect of the present invention (FIG. 7(B)) has fewer locations that can become corrosion starting points, as indicated by arrows.

The fourth aspect of the invention is defined as follows. That is,
In the overlay layer defined in the third aspect, the total strength of the (110) plane and the (202) plane is 20% or less of the total strength of the entire surface, based on the X-ray diffraction intensity.
In other words, the total orientation ratio of the (110) plane and the (202) plane is 20% or less.
A decrease in the total orientation ratio of the (110) plane and the (202) plane indicates that many of the crystal planes of the crystals constituting the sliding surface tend to be close to perpendicular to the sliding surface. Therefore, by reducing the total orientation ratio of these crystal planes, the number of corrosion starting points on the sliding surface is further reduced.

FIG. 1 shows the orientation ratio of each crystal plane by X-ray diffraction of a standard Bi sample calculated from the example described in Patent Document 1. FIG. 3 shows the orientation ratio of each crystal constituting the surface of the Bi film, as determined by X-ray diffraction of the Bi film calculated from the example described in Patent Document 2. FIG. 3 shows the orientation of crystals constituting an overlay layer obtained as an example of the present invention. FIG. 4 shows the orientation of crystals constituting an overlay layer obtained as another example of the present invention. FIG. 5 is a schematic diagram of a film having crystals exhibiting different orientations constituting a Bi layer formed by a conventional method (Patent Document 1) and a method of the present invention, and is a schematic diagram of a film having crystals exhibiting different orientations. represents a characteristic. FIG. 5(A) schematically shows a cross section of a Bi layer formed by the wet plating method in which the orientation rate is largely biased towards a specific crystal plane, and FIG. 5(B) shows a Bi layer formed by the method of the present invention. This schematically shows a cross section in which the orientation ratio of the layer is biased toward a specific crystal plane. FIG. 6 schematically represents the features of the third and fourth aspects of the invention. FIG. 7 is a schematic diagram showing a crystal constituting a Bi layer formed by a conventional method (Patent Document 2) and a method of the present invention, and a plurality of planes constituting the crystal. It represents the characteristics of the surface (number of corrosion starting points). FIG. 7(A) schematically shows a cross section perpendicular to the sliding surface of the Bi layer formed by the wet plating method, and FIG. 7(B) schematically shows the sliding surface of the Bi layer formed by the method of the present invention. A vertical cross section is schematically shown. FIG. 8 is a sectional view schematically showing the structure of a sliding bearing according to an embodiment of the present invention. FIG. 9 schematically shows the configuration of a manufacturing apparatus according to an embodiment of the present invention. FIG. 10 shows the load pattern applied to the sliding bearing when conducting the fatigue test. FIG. 11 is a plan view (projection view) showing the sliding surface (Bi overlay layer surface) of the sliding bearing after the fatigue test.

Hereinafter, this invention will be explained based on examples.
In this embodiment, an example in which a Bi-based layer is formed as the overlay layer 7 of the half bearing is adopted.
As shown in FIG. 8, a copper-based bearing alloy layer 5 is laminated on a half-cylindrical back metal layer 3 as a substrate, and an overlay layer 7 made of Bi or Bi alloy is vacuum-deposited thereon to form a plain bearing 1. Form.
The bearing alloy layer 5 is laminated onto the back metal layer 3 by sintering. After sintering, it is shaped into a half-cylindrical shape, and the inner surface is cut to give it the same wall thickness. The thickness of the back metal layer 3 is 1.20 mm, and the thickness of the axial alloy layer 5 is 0.30 mm. The laminated body of the backing metal layer 3 and the bearing alloy layer 5 is used as a substrate, and this is set in a vacuum chamber of a vacuum evaporation apparatus so as to face the evaporation source. Furthermore, the evaporation source contains Bi, which is an evaporation material.

For the bearing alloy layer 5, Cu, Sn, and alloys thereof can be used in addition to Al and its alloys. The thickness and material of the bearing alloy layer 5 can be selected as appropriate depending on the application of the bearing, and the layers are laminated by a method such as pressure welding, sintering, casting, physical vapor deposition, chemical vapor deposition, thermal spraying, or plating.
An intermediate layer made of Ag, Ni, etc. may be formed on the bearing alloy layer 5. The formation method is not particularly limited, but physical vapor deposition, chemical vapor deposition, thermal spraying, plating, etc. can be employed.

The final thickness of the overlay layer 7 deposited on the bearing alloy layer 5 is between 2 and 20 μm.
Note that the vacuum degree of the vacuum chamber was 5.0×10 ⁻³ Pa, and the film formation rate was 15 μm/min. These vacuum degrees and film-forming speeds are adjusted as appropriate depending on the performance required of the overlay layer 7, the environment in which it is used, the specifications of the manufacturing equipment, and the like.

In this invention, when the overlay layer 7 is vacuum-deposited, only the outermost layer thereof is brought into a liquid phase. Therefore, it was decided to irradiate the growth surface of the overlay layer 7 with infrared rays in pulses.
FIG. 8 shows a manufacturing apparatus 10 used in the method of manufacturing a sliding bearing according to the present invention.
This manufacturing apparatus 10 includes a substrate holder 13, a evaporation source 15, a vacuum pump 17, and a vacuum gauge 19 in a vacuum chamber 11 that constitutes a general-purpose vacuum evaporation apparatus. Reference numeral 16 is a heating device for the vapor deposition source.

In this manufacturing apparatus 10, a temperature control section 21 is provided in the substrate holding section 13. As this temperature control section 21, a plate-shaped heat exchanger using a refrigerant such as water as a heat medium is used. Then, the temperature of the substrate holding surface of the substrate holding section 13 is controlled by adjusting the heat exchange capacity of the heat exchanger. Furthermore, by adjusting the thermal conductivity of the spacer interposed between this heat exchanger and the substrate holding section 13, the temperature of the substrate holding surface can be controlled.

A vapor deposition source 15 is arranged on the bottom wall 12 of the vacuum chamber 11 so as to face the substrate holder 13 . This vapor deposition source 15 has a gutter shape corresponding to the half-cylindrical substrate, and is heated by a heating device 16 . On both sides of the vapor deposition source 15 in the bottom wall 12 of the vacuum chamber 11, windows 23 are formed of quartz glass or the like and have windows 23 through which non-ionizing radiation such as infrared rays can pass. radiated in the direction. At this time, the vapor deposition source 15 is prevented from interfering with infrared rays. Thereby, the entire surface of the substrate can be uniformly irradiated with infrared rays.

As the infrared source 25, two halogen lamps were prepared along the vapor deposition source 15, that is, facing the half-cylindrical substrate. Their output characteristics are pulse width: 1 second, duty cycle: 50%, and total output power is 750W. Reference numeral 27 is a halogen lamp controller.

A dummy sample 30 was used to set conditions for selectively bringing the growth surface of the overlay layer into a liquid phase state.
In this example, a dummy sample 30 was prepared by laminating a copper-based bearing alloy layer 5 on a half-cylindrical back metal layer 3 used as a substrate. Thermocouples 31 and 32 as thermometers are attached to both sides of this dummy sample 30, and the temperature of each surface is measured. This dummy sample 30 is set in the substrate holding section 13 of the vacuum chamber 11, and the heat exchange capacity of the temperature control section 21 is adjusted. At the same time, the output of the infrared ray source 25 is adjusted using the controller 27, so that the temperature of the front surface of the dummy sample 30 (overlay layer growth surface side) and the back surface of the dummy sample 30 (substrate holder side) reach a predetermined temperature. I did it like that.

When producing the overlay layer of the plain bearing, the amount of circulating cooling water is controlled to adjust the heat exchange capacity of the temperature control unit 21, and on the other hand, the output of the halogen lamp, which is an infrared source, is adjusted in the range of 50 to 100%. did. As a result, conditions for the temperature control unit 21 and the controller 27 are found and specified so that the surface temperature of the dummy sample 30 is stabilized at 273° C., which is the melting point of Bi, and 140° C. on the back surface.
Note that the vacuum degree of the vacuum chamber was set to 5.0×10 ⁻³ Pa, which is the same as when growing the overlay layer.
The output conditions of the infrared source can also be adjusted by adjusting the pulse width, pulse amplitude, duty cycle, etc.

The cooling capacity of the temperature control unit 21 for the back surface of the dummy sample 30 (the second amount of heat applied to the back surface per unit area and unit time) and the amount of infrared rays irradiated to the surface (the amount of infrared rays applied to the surface per unit area and unit time) The balance of the first amount of heat applied) forms hot and cold regions in the dummy sample 30, ie, the growing overlay layer.

The heat exchange capability of the temperature control unit 21 and the output of the infrared ray source 15 thus specified are adjusted to form the overlay layer 7 made of Bi.
That is, a workpiece formed by laminating the bearing alloy layer 5 on the backing metal layer 3 is set in the substrate holding part 13 as a substrate. The vacuum pump 17 is operated to achieve a desired degree of vacuum in the vacuum chamber 11, and the heat exchange capacity of the temperature control section 21 is set to the above specified value.
After the degree of vacuum becomes stable, the heating device 16 is operated to start heating the Bi raw material as the evaporation source. At the same time that the Bi is heated to a temperature at which it evaporates, the infrared ray source 25 is activated. The output is as specified above.
The growth rate of the overlay layer was 15 μm/min. As a result, a sliding bearing having an overlay layer having the thickness shown in Table 2 was manufactured.

The thus obtained overlay layer was measured from the growth surface side by X-ray diffraction measurement using Cu-kα rays. The X-ray diffraction conditions were as follows.
From the obtained results, the orientation of the crystals constituting the overlay layer was as shown in FIG. 3. Comparing the results in FIG. 3 with FIG. 1, it can be seen that the orientation ratio of the (012) plane is small, and the orientation ratios of the (015) plane and the (107) plane are increasing.
This means that, compared to the orientation shown in FIG. 1, the orientation shown in FIG. 3 has a smaller bias in the orientation ratio toward a specific crystal plane on the sliding surface (the surface of the overlay layer) with respect to the sliding surface. That is, since the probability that crystals having the same orientation exist in close proximity decreases, the propagation of cracks in the film thickness direction is inhibited. This makes it easier for the overlay layer to withstand deformation due to the load from the sliding surface, and the fatigue resistance of the overlay layer is greatly improved.

The properties of the overlay layer of Example 1 obtained as described above were as follows. That is, the ratio of the total value of the orientation rate of the (015) plane and the orientation rate of the (107) plane to the orientation rate of the (012) plane (formula 1: {R(015)+R(107)}/R( 012)) was 1.00.
Furthermore, the ratio (R3/Rmax) of the strength R3 of the surface having the third strongest peak intensity (third orientation ratio) to the strength Rmax (maximum orientation ratio) of the surface having the maximum strength is 0.30. Ta.

The fatigue test was conducted as follows.
The sliding bearing of Example 1 was set in a test device having an eccentric shaft and capable of applying a dynamic load as it rotated. By controlling the oil pressure, the load applied to the bearing was gradually increased as shown in FIG. 10, and a fatigue test was conducted at a surface pressure of 120 MPa for 20 hours.
The detailed test conditions are as follows.
Bearing dimensions (mm): Outer diameter OD (56) x axial length L (14) x thickness T (1.5)
Rotation speed: 3250rpm
Lubricating oil: VG68
Lubricating oil temperature: 100℃
Shaft material: S55C (quenched, surface roughness: Ra0.06)

After a 20-hour fatigue test, a plan view (projection view) of the sliding surface of the plain bearing is shown in FIG. Reference numeral 34 in the figure represents an image of fatigue failure of the overlay layer.
The area where the symbol 34 appears is defined as a fatigue area, and the area of the fatigue area is approximated by an ellipse 36, and the area ratio of the fatigue area to the entire sliding surface is calculated. In the sliding bearing of Example 1, the value is was 0.35.

Table 2 describes the specifications and characteristics of other Examples 2 to 9 and Comparative Examples 1 to 3, following the example 1.

In Examples 2 to 9 and Comparative Example 3, the heat exchange capacity of the temperature controller 21 and the output of the infrared ray source 25 were adjusted to control the surface temperature (above the melting point of Bi) and the back surface temperature (above the melting point of Bi) of the dummy sample 30. (below the melting point of). In Table 2, the relationship between the two is expressed as the ratio of surface temperature/back surface temperature.
Other substrate conditions (material and thickness of backing metal layer 3 and bearing alloy layer 5), overlay layer growth conditions (material, degree of vacuum, growth rate), and fatigue test evaluation (fatigue area area/sliding surface area) are as follows: Same as Example 1.
In Comparative Example 2, the second amount of heat is applied to the workpiece only from the substrate side, resulting in a substantially uniform temperature within the overlay layer during growth. In Comparative Example 3, the entire overlay layer was destroyed and disappeared in the fatigue test.

On the premise that the ratio of Equation 1 is as above, the comparison of the fatigue test results of Examples 4 to 9 in Table 2 with those of Examples 1 to 3 shows that the value of R3/Rmax is 0. It can be seen that when the value is 40 or more, excellent fatigue resistance is exhibited. It is more preferable that the ratio is 1.5 to 1.7 and the value of R3/Rmax is 0.4 or more. More preferably, the value of R3/Rmax is 0.45 or more.

Next, Example 10 will be explained.
In this Example 10, the surface temperature of the dummy sample 30 was maintained at 273° C., and the heat exchange ability of the temperature control unit 21 and the output of the infrared ray source 25 were adjusted so that the back surface temperature was 80° C. The overlay layer was grown under the adjusted conditions and other growth conditions that were the same as in Example 1.

The overlay layer thus obtained was measured by X-ray diffraction in the same manner as above, and the results shown in FIG. 4 were obtained.
From the orientation shown in FIG. 4, it can be seen that the sliding surface of this overlay layer is strongly influenced by crystal grains having (104) planes.
This means that, compared to the orientation shown in FIG. 2, the orientation shown in FIG. This indicates that there are a large number of corrosion-resistant materials, which means that there are fewer corrosion starting points exposed on the surface, which improves corrosion resistance.

The properties of the overlay layer of Example 10 obtained as described above were as follows. That is, the orientation ratio of any one of the (104) plane, the (015) plane, and the (107) plane was the highest, and the total of these orientation ratios was 70.0%.
Further, the total orientation ratio of the (110) plane and the (202) plane was 25.0%.

Table 3 describes the specifications and characteristics of other Examples 11 to Comparative Examples 16, Comparative Examples 4, and Comparative Examples 5, following Example 10.

In Table 3, the corrosion depth indicating corrosion resistance was specified as follows.
The manufactured plain bearing is immersed in an oil pool. Helix Ultra SN 10W-30 manufactured by SHELL was used as the oil, and the immersion conditions were 130° C. and 600 hours. The cross section of the overlay layer made of Bi before immersion and the overlay layer after immersion treatment, each parallel to the axial direction at the center in the circumferential direction, was observed with an optical microscope, and the difference between them was taken as the depth of the corroded layer.
In Example 10, 3.0 μm, or 30% of the overlay layer, was lost due to corrosion.

In Examples 11 to 16, the heat exchange capacity of the temperature control unit 21 and the output of the infrared ray source 25 are adjusted to adjust the surface temperature (above the melting point of Bi) and the back surface temperature (below the melting point of Bi) of the dummy sample 30. stabilized. In Table 2, the relationship between the two is expressed as the ratio of surface temperature/back surface temperature.
Other substrate conditions (material and thickness of the backing metal layer 3 and bearing alloy layer 5) and overlay layer growth conditions (material, degree of vacuum, growth rate) are the same as in Example 1, and the corrosion resistance evaluation method is also the same as in Example 1. Same as 10.

From the comparison between Examples 10 to 16 and Comparative Examples 4 and 5, it was found that the orientation ratio of any one of the (104) plane, (015) plane, and (107) plane is the maximum, and It can be seen that it is preferable that the total ratio is 70% or more. More preferably, it is 80% or more. Further, the upper limit is not particularly limited, but it is preferably 95% or less.
In Example 11, when the value of the ratio of surface temperature/back surface temperature was set to 4.6, the orientation rate of any one of the (104) plane, (015) plane, and (107) plane was maximum, and these orientation rates The total of The total orientation rate decreased to 15% (the ratio of oriented surfaces that could become corrosion starting points was small). As a result, the corrosion thickness of the overlay layer was 1.2 μm, which showed a significant improvement in corrosion resistance compared to Example 10.
From these results, the total orientation ratio of the (110) plane and the (202) plane is preferably 20% or less, more preferably 15% or less.

As explained above, in the overlay layer obtained by selectively bringing the growth surface of the overlay layer into a liquid phase state when Bi is vacuum-deposited onto the substrate, the orientation of the crystals constituting the overlay layer is , it can be seen that the overlay layer is different from that of the overlay layer produced by the general-purpose physical vapor deposition method and wet plating method.
Furthermore, it is clear from the results in Figures 3 and 4 that by changing the balance between the amount of heat applied to the growth side and the amount of heat applied to the opposite side, the orientation of the crystals that make up the resulting overlay layer can be controlled. became.
It can be seen that as a result of controlling the crystal plane orientation in this manner, the characteristics of the obtained overlay layer also change.
Although Bi has been described above as a constituent material of the overlay layer, it is possible to change or control the crystal orientation of other metals as well.

This invention is in no way limited to the description of the embodiments of the invention described above. This invention includes various modifications that can be easily conceived by those skilled in the art without departing from the scope of the claims. A device using a bearing mechanism, such as an internal combustion engine, using the sliding member of the present invention exhibits excellent sliding characteristics.
Although the embodiment has been described using a semi-cylindrical sliding bearing as an example of the sliding member, the present invention can also be applied to other sliding members such as a flat plate-shaped thrust washer.

1... Sliding bearing 3... Back metal layer 5... Bearing alloy layer 7... Overlay layer 10... Manufacturing device 11... Vacuum chamber 13... Substrate holding section 15... Evaporation source 17... Vacuum pump 21... Temperature control section 25... Infrared source 30... Dummy Samples 31, 32...Thermocouple 34...Image of fatigue failure of overlay 36...Fatigue area

Claims (9)

A method for manufacturing an overlay layer made of Bi or a Bi alloy by a physical vapor deposition method, the method comprising: a first layer capable of melting the Bi or Bi alloy toward a growth surface side to which the Bi or Bi alloy is supplied in the overlay layer being grown; a second amount of heat capable of maintaining the opposite surface at a temperature lower than the melting point of the Bi or Bi alloy to the opposite side of the growing overlay layer located on the opposite side to the growth surface. . A method of manufacturing an overlay layer, wherein a high temperature region is generated on the growth side and a low temperature region is generated on the opposite side of the growing overlay layer. 2. The method of claim 1, wherein the first amount of heat is provided by non-ionizing radiation. 3. The manufacturing method according to claim 2, wherein the non-ionizing radiation is pulsed. 4. The manufacturing method according to claim 2, wherein the physical vapor deposition method is a vacuum deposition method, and the non-ionizing radiation is infrared rays, and the growth surface of the overlay layer is uniformly irradiated. 5. The manufacturing method according to claim 4, wherein the infrared radiation source is arranged to sandwich the vapor deposition source. 6. The method according to claim 1, wherein the crystal orientation of Bi or Bi alloy constituting the overlay layer is controlled by controlling the difference between the first amount of heat and the second amount of heat. Production method. A method of manufacturing an overlay layer made of Bi or a Bi alloy by a physical vapor deposition method using a physical vapor deposition apparatus , the method comprising: producing a high temperature region on the growth surface side of the overlay layer during growth and producing a low temperature region on the opposite surface thereof. A method of manufacturing an overlay layer, comprising:
The high temperature region is heated to a temperature higher than the melting point of the Bi or Bi alloy by non-ionizing radiation from a heating device other than the physical vapor deposition device , and the low temperature region is maintained below the melting point of the Bi or Bi alloy. method of manufacturing the overlay layer. A method of manufacturing an overlay layer made of Bi or a Bi alloy by a physical vapor deposition method using a physical vapor deposition device , the outermost layer on the growth side of the overlay layer being grown is heated by non-ionizing heat from a heating device other than the physical vapor deposition device. A method for producing an overlay layer that is selectively brought into a liquid phase state by radiation . A method for manufacturing a plain bearing, comprising the step of manufacturing an overlay layer according to any one of claims 1 to 8.

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