JP2005076075A - Thermal spray coating, forming method therefor and bearing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal spray coating which does not contain lead and has superior sliding characteristics, high strength and superior adhesiveness, and also to provide a forming method therefor, and a bearing member with the thermal spray coating. <P>SOLUTION: A powder to be thermally sprayed onto a surface of a substrate is prepared by mixing, by weight percentage, a 5 to 25% Sn powder with a 95 to 75% Al powder. Here, the Sn powder has preferably a particle diameter of 0.5 to 0.8 times larger than that of the Al powder. Alternatively, the powder to be thermally sprayed onto the surface of the substrate is prepared so as to comprise, by weight percentage, 15 to 40% Sn and the balance copper with unavoidable impurities. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermal spray coating formed by spraying metal particles on a substrate surface, a method for forming the thermal spray coating, and a bearing member.

  By forming the thermal spray coating on the sliding portion of the bearing member, the bearing member can be reduced in size and weight. In recent years, a technique related to a bearing member in which such a thermal spray coating is formed has been reported (for example, Patent Document 1). The bearing material disclosed in this document relates to a bronze bearing material having a special structure formed by thermal spraying. That is, the structure of the sprayed layer is a mixed structure of an undissolved structure of bronze atomized powder and a layered sprayed structure in which lead is forcibly solid-solved, or an undissolved structure of powder containing 3 to 40% lead. It is a mixed structure with a dissolved structure containing or not containing less than 3% lead. By having a thermal sprayed layer of such a structure, it is said that a bearing material having excellent sliding characteristics, high hardness and excellent adhesion can be obtained. However, in this technique, a large amount of lead is mainly used as a sliding component.

The so-called “EU scrap car directive” that came into force in October 2000 prohibits the use of heavy metals such as lead, mercury, cadmium and hexavalent chromium in automobile parts in principle. For this reason, development of the thermal spray bearing member which does not contain lead in a sliding part was desired.
Japanese Patent No. 2965192

  This invention is made | formed in view of the above situation, and the 1st objective of this invention is to provide the thermal spray coating which was excellent in the sliding characteristic which does not contain lead, was high intensity | strength, and was excellent in adhesiveness. A second object of the present invention is to provide a method for forming a thermal spray coating that is excellent in sliding properties not containing lead, has high strength, and has excellent adhesion. Furthermore, the third object of the present invention is to provide a bearing member in which a thermal spray coating excellent in sliding characteristics not containing lead, having high strength and excellent adhesion is formed.

  The present inventor has found that by containing a large amount of Sn in the thermal spray coating, it is possible to obtain a thermal spray coating excellent in sliding properties, high strength and excellent adhesion, and completed the present invention.

  The invention relating to the thermal spray coating of claim 1 is the first invention of the present invention, and in order to achieve the first object, a thermal spray coating formed by spraying metal particles on the surface of the substrate, The metal particles are a mixed powder obtained by mixing 5 to 25% by weight of Sn powder and 95 to 75% by weight of Al powder.

  In order to achieve the first object, the invention according to claim 2 is characterized in that, in the invention according to claim 1, the particle size of the mixed powder is 10 to 75 μm. is there.

  In order to achieve the first object, the invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the particle size of the Sn powder is 0.5 to the particle size of the Al powder. It is characterized by being -0.8.

The invention related to the thermal spray coating of claim 4 is the second invention of the present invention, and in order to achieve the first object, a thermal spray coating formed by spraying metal particles on the surface of the substrate,
The metal particles contain 15 to 40% Sn by weight, and the balance is a powder made of copper and inevitable impurities.

  In order to achieve the first object, the invention according to claim 5 is characterized in that, in the invention according to claim 4, the powder has a particle size of 10 to 45 μm. .

  In order to achieve the first object, the invention related to the sprayed coating of claim 6 is characterized in that, in the invention of claim 4 or 5, the oxygen concentration in the sprayed layer is less than 4% by weight. It is what.

  The invention relating to the method for forming a thermal spray coating according to claim 7 is the third invention of the present invention, and in order to achieve the second object, 5 to 25% Sn and 95 to 75% by weight are obtained. A thermal spray coating is formed by spraying a mixed powder obtained by mixing Al powder on the surface of a base material.

  The invention relating to the method for forming a sprayed coating according to claim 8 is the fourth invention of the present invention, and in order to achieve the second object, it contains 15 to 40% by weight of Sn, with the balance being copper. And the powder which consists of an unavoidable impurity is sprayed on the base-material surface, and a sprayed coating is formed.

  The invention related to the method for forming a thermal spray coating according to claim 9 is characterized in that, in order to achieve the second object, in the invention according to claim 8, the base material is preheated to 200 to 300 ° C. Is.

  The invention related to the method for forming a thermal spray coating according to claim 10 is characterized in that, in order to achieve the second object, in the invention according to claim 9, the number of times the thermal spray coating is laminated is one. Is.

  The invention related to the bearing member according to claim 11 is the fifth invention of the present invention, and in order to achieve the third object, the bearing member is formed by spraying metal particles on the surface of the substrate to form a sprayed coating. The metal particles are a mixed powder obtained by mixing 5 to 25% by weight of Sn powder and 95 to 75% by weight of Al powder.

  The invention related to the bearing member of claim 12 is the sixth invention of the present invention, and is a bearing member in which a thermal spray coating is formed by spraying metal particles on the surface of the substrate in order to achieve the third object. The metal particles contain 15 to 40% by weight of Sn, and the balance is a powder made of copper and inevitable impurities.

  Since the thermal spray coating of the first invention of the present invention is formed by thermal spraying Al powder and Sn powder as a mixed powder, Sn can be uniformly dispersed in the thermal spray coating. Therefore, it is possible to obtain a good thermal spray coating having high surface pressure fatigue strength and high seizure strength.

  Moreover, the thermal spray coating of 2nd invention of this invention can suppress the oxidation of a thermal spray coating by containing a lot of Sn in Cu. Accordingly, curing of the thermal spray coating can be suppressed, and the thermal spray powder can be melted at a high temperature, so that a thermal spray coating having high adhesion strength with the base material and high surface pressure fatigue strength can be obtained. Furthermore, according to the present alloy powder, it is possible to increase the amount of powder supplied at the time of thermal spraying and reduce the number of times the thermal spray coating is laminated (the number of thermal gun passes). Thereby, there exists an effect which improves the quality of the formed sprayed coating, and improves productivity remarkably.

  The bearing member of the present invention can be suitably used as a connecting rod for an automobile internal combustion engine.

  The bearing member of the present invention greatly contributes to the reduction in size and weight of the bearing member and further contributes to the improvement of fuel consumption.

  First, an embodiment of the first invention will be described with reference to FIGS.

  When an Al—Sn alloy powder is plasma sprayed to form a sprayed coating, Sn is not readily solid-solved in Al, so Sn is deposited on the sprayed alloy powder surface. Sn has a melting point of 232 ° C., which is extremely low compared to 660 ° C. of Al. For this reason, as shown in FIG. 12, in the thermal spray coating 1, Sn3 deposited on the particle surface from the adjacent thermal spray particles melts and fuses together to obtain a thermal spray structure enclosing the Al particles 2. In such a sprayed structure, since the strength of Sn is lower than that of Al, when a tensile force acts on the sprayed coating 1, a crack C is generated along the fused Sn3. Therefore, the strength of the sprayed coating 1 is low. FIG. 13 shows a mapping image by EPMA of the sprayed coating obtained by spraying Al-10% Sn alloy powder. a is a mapping image of Al and b is a mapping image of Sn. It can be seen that Sn fused between Al forms a continuous surface.

  The sprayed coating of the first invention is a sprayed coating formed by mixing Sn powder with Al powder and spraying this mixed powder. In the spray coating formed in this way, as shown in FIG. 1, a sprayed structure 1 in which molten Sn3 is dispersed and solidified in the layer of Al particles 2 is obtained, and the Al particles 2 support the sliding load and disperse. Thus, the melted and solidified Sn3 can ensure seizure strength as a sliding component. FIG. 2 shows an EPMA mapping image of a sprayed coating obtained by spraying a mixed powder obtained by mixing 10% by weight of Sn powder with Al powder. a is a mapping image of Al and b is a mapping image of Sn. Here, it can be seen that Sn is dispersed and solidified in Al.

The thermal spray coating of the first invention is a thermal spray coating formed by spraying metal particles on the surface of a substrate, and the metal particles are 5 to 25% Sn powder and 95 to 75% Al by weight percentage. It is a mixed powder obtained by mixing powder. (Hereafter, “%” means “% by weight”.)
FIG. 3 shows changes in the surface pressure fatigue strength of the sprayed coating and changes in the seizure load with respect to the amount of Sn powder. The left vertical axis represents the surface pressure fatigue strength of the film, and the right vertical axis represents the seizure strength. Here, the surface pressure fatigue strength is a fatigue strength at which the thermal spray coating is damaged by applying repeated surface pressure (tapping) from the shaft to the bearing. That is, a cylindrical shaft is inserted into a thermal spray bearing having a thermal spray coating formed by spraying a predetermined mixed powder, the shaft is rotated at a predetermined peripheral speed, and the surface of the thermal spray coating and the outer peripheral surface of the shaft with a constant surface pressure. The surface pressure fatigue strength is defined as the contact pressure at which the sprayed coating breaks by repeating contact and non-contact.
In the present embodiment, the contact surface pressure was varied in the range of 70 to 100 MPa, a surface pressure of 3000 times / minute was generated, and the surface pressure at which the sprayed coating was damaged 10 ⁷ times was defined as the surface pressure fatigue strength. The peripheral speed of the shaft was 6.7 m / sec.

  In FIG. 3, the surface pressure fatigue strength (indicated by ■) of the thermal spray coating decreases as the amount of Sn powder in the mixed powder increases. In particular, it can be seen that when the blending amount of Sn powder exceeds 25 wt%, it rapidly decreases. This is presumably because the probability that the Sn particles are adjacent to each other in the thermal spray coating increases as the blending amount of the Sn powder increases, and it becomes easy to fuse together.

  On the other hand, since Sn is a sliding component as is well known, the seizure load (indicated by ♦) of the thermal spray coating increases as the amount of Sn powder increases.

  As described above, the surface pressure fatigue strength and the seizure strength of the sprayed coating exhibit opposite behaviors as the amount of Sn powder increases. Therefore, it is desirable to select the blending amount of Sn powder within the range satisfying both characteristic values in accordance with the characteristic values required for the thermal spray coating. That is, if the amount of Sn powder is less than 5% by weight, a sufficient seizure resistance load cannot be obtained. Moreover, when the compounding quantity of Sn powder exceeds 25 weight%, sufficient surface-pressure fatigue strength cannot be obtained. Therefore, it is desirable that the total amount of the mixed powder is 100% by weight and the amount of Sn powder is 5 to 25% by weight. A more preferable blending amount of the Sn powder is 10 to 15% by weight with respect to 100% by weight of the mixed powder.

  The particle size of the mixed powder is desirably 10 to 75 μm. If the particle size of the mixed powder is less than 10 μm, it is easy to melt, so that stable spraying cannot be obtained, and if it exceeds 75 μm, the mixed powder may be insufficiently melted. More preferably, it is 45-75 micrometers.

  By the way, when powders having the same Al and Sn particle sizes are mixed and sprayed as described above, Sn3 may be sprayed in the sprayed coating 1 with a bias toward the substrate 4 as shown in FIG. . This is because the specific gravity of Al is about 2.7 and the specific gravity of Sn is as large as about 7.3, and the difference in specific gravity between the two is large. When Al powder and Sn powder with the same particle size are supplied into the plasma jet as a mixed powder, the initial speed of Sn powder jumping out from the tip of the powder supply section is slower, so it reaches deep into the plasma jet. Can not do it. For this reason, since it reaches the surface of the base material earlier than the Al particles, Sn3 is biased toward the base material surface side. When the spray gun is moved in parallel to the substrate surface and sprayed by one movement (one-pass condition), this Sn bias appears remarkably. If the multi-pass condition is used, this unevenness of Sn can be eliminated. However, in this case, a thermal spray coating is laminated, and an oxide is formed between the layers, which may cause delamination.

  Therefore, by reducing the particle size of the Sn powder relative to the Al powder and making the weight of the Al powder particles and the weight of the Sn powder particles approximately the same, the Al particles and the Sn particles can be made substantially the same as the base material. To reach the surface. Thus, by setting the weight of the particles to the same level, Sn can be uniformly dispersed in the sprayed coating as shown in FIG.

  When powders having different specific gravities are used as mixed powders, the manner of dispersion in the film varies depending on the particle size of the powders to be mixed. FIG. 6 shows the relationship between the difference in particle size between Al powder and Sn powder and the dispersion state of Sn in the film. That is, the ratio of the average particle diameter of Sn to the average particle diameter of Al (hereinafter referred to as the particle diameter ratio) as the horizontal axis and the Sn dispersion ratio as the vertical axis, The change in the dispersion rate is shown. Here, the dispersion ratio represents the variation in the area ratio of Sn on the base material side and the surface side of the thermal spray coating. As shown in FIG. 7, the thermal spray coating is divided into two equal parts in the thickness direction in an arbitrary thermal spray coating cross section, and the coating on the surface side from the middle is A, and the coating on the substrate side from the middle is B. The area ratio of Sn in A is a, the area ratio of Sn in B is b, and the dispersion ratio is defined as the absolute value of (ab). That is, the larger the dispersion rate, the larger the bias of Sn in the sprayed coating, and the closer the dispersion rate is to 0, the more uniformly the Sn is dispersed in the sprayed coating. From FIG. 6, the dispersion rate of Sn decreases as the particle size ratio increases until the particle size ratio is around 0.7. Thereafter, when the particle size ratio increases to 1, that is, when the particle sizes of the AL powder and the Sn powder coincide, the dispersion ratio becomes about 10%.

  In order to obtain a stable surface pressure fatigue strength of the sprayed coating, the dispersion ratio is desirably 0.5% or less. That is, the particle size of the Sn powder with respect to the particle size of the Al powder is desirably 0.5 to 0.8.

  Hereinafter, the thermal spray coating of the first invention will be described in more detail with reference to specific examples.

  FIG. 8 is a specific example in which the surface pressure fatigue strength of the thermal spray coatings according to the type of thermal spray powder is compared. The horizontal axis represents the type of powder, and the vertical axis represents the surface pressure fatigue strength of the thermal spray coating formed by spraying the powder. A is a mixed powder in which 10% by weight of Sn powder having an average particle diameter of 25 μm is blended with Al powder having an average particle diameter of 60 μm. B is a mixed powder in which an Al powder having an average particle size of 60 μm is blended with 10 wt% of an Sn powder having an average particle size of 60 μm, which is similar to that of the Al powder. C is an Al—Sn alloy powder having an average particle diameter of 60 μm in which 10% by weight of Sn is mixed with Al. The surface pressure fatigue strength of A and B sprayed with the mixed powder was higher than that of C sprayed with the alloy powder. Further, in the mixed powder spraying, A using the mixed powder having a smaller particle diameter of the Sn powder than the Al powder has a higher surface than B using the mixed powder having the same particle diameter. It can be seen that the pressure fatigue strength is shown.

  FIG. 9 shows the results of measuring 20 Vickers hardnesses (HV: 0.2) at room temperature for each thermal spray coating formed using the powder B and the powder C, respectively. The average hardness is slightly higher than B, which is a mixed powder, compared to C, which is an alloy powder. However, the hardness variation shown by the bold line in the figure is extremely large at HV30 to HV80, whereas B Then, it turns out that it is small with HV50-HV70. From this, it is inferred that Sn is uniformly dispersed in the sprayed coating by spraying the mixed powder. That is, the sprayed coating using the mixed powder B can suppress variations in coating hardness, and as a result, variations in the amount of wear of the sprayed coating can be reduced.

  FIG. 10 shows the change in high temperature hardness in the heated state of the thermal spray coating. The results of the thermal spray coating (♦) with the mixed powder B and the thermal spray coating (◇) with the alloy powder C are also shown. In either case, the hardness of the coating decreases as the temperature increases. However, the degree of decrease is smaller in the mixed powder B than in the alloy powder C. That is, by dispersing Sn in the sprayed coating, it is possible to suppress a decrease in high-temperature hardness and to prevent a decrease in wear resistance in a high-temperature state. It can be seen that Sn can be easily reduced in high-temperature hardness, but can be suppressed by uniformly dispersing Sn.

  The thermal spray coating of the second invention is a thermal spray coating formed by spraying metal particles on the surface of the substrate, and the metal particles contain 15 to 40% by weight of Sn, with the balance being copper and inevitable. It is characterized in that it is a powder composed of mechanical impurities.

  FIG. 14 shows the change in the oxidation amount (oxygen concentration expressed in weight percentage) of the sprayed coating depending on the amount of Sn in the Cu alloy. It can be seen that the amount of oxidation decreases as the Sn content increases. The oxidation amount reaches a minimum of about 2.8% when the Sn content is around 35%, and then increases slightly to about 3.2% when the Sn content is 50%. Since the oxidation amount in the Cu alloy powder having a conventional Sn content of 5% is about 5.8%, it can be seen that the increase in the Sn content significantly suppresses the oxidation of the sprayed coating. This is presumably because, as a result of Sn being dissolved in Cu, Cu and Sn formed an ordered atomic arrangement of oxygen, so that oxygen became difficult to diffuse into the ordered lattice.

Since the oxidation of the thermal spray coating can be suppressed as described above, the following useful effects can be exerted on the characteristics of the thermal spray coating.
1) Curing of the sprayed coating can be suppressed.

FIG. 15 shows changes in film hardness depending on the Sn content. The film hardness decreases with an increase in Sn content, and becomes HV120 when the Sn content is around 15%, and becomes the lowest HV100 around 25%. When the Sn content further increases, the film hardness gradually increases, and when the Sn content is around 40%, it becomes HV120 again and the hardness is further increased. That is, it can be understood that the coating can be suppressed since the oxidation of the sprayed coating can be suppressed by increasing the Sn content. For example, when forming a film having a hardness of HV120 or less in order to ensure compatibility with the counterpart material, it is understood that the Sn content in the Cu alloy may be 15 to 40%.
2) The elongation rate of the sprayed coating can be improved.

FIG. 16 shows the relationship between the Sn content and the elongation percentage of the film. Here, the elongation rate indicates the rate of increase in length with respect to the tensile stress of the thermal spray coating. That is, the elongation rate indicates the deformation limit amount of the thermal spray coating, and a higher value is a preferable value. As can be seen from FIG. 16, as the Sn content increases, the elongation increases and reaches a maximum value of about 0.35% when the Sn content is around 30%. Further, when the Sn content is increased, the elongation rate slightly decreases. That is, since the oxidation of the film is suppressed as the Sn content increases, the elongation rate of the film can be improved. For example, when the bearing member is a connecting rod, the elongation ratio of the sprayed coating necessary to cope with the strain of the connecting rod during operation is 0.2% or more, and the target value is indicated by a dotted line in FIG. It can be seen that a conventional alloy of Cu-5% Sn cannot obtain a sufficient elongation, but it is easy to improve the elongation of the film by increasing the amount of Sn.
3) A thermal spray coating with high surface pressure fatigue strength can be formed.

  By using a material that does not easily oxidize as described above, the thermal spray coating is hard to be cured even if the heat of fusion of the powder is increased. Thus, by increasing the heat of fusion of the powder, the adhesion between the powder particles can be increased, and the surface pressure fatigue strength of the thermal spray coating can be improved.

FIG. 17 shows the change in the surface fatigue strength due to the heat of fusion of the powder of the thermal spray coating using Cu-25% Sn powder as the thermal spray powder. The horizontal axis represents electric power (kW) for generating plasma as heat of fusion. It can be seen from FIG. 17 that the contact fatigue strength is improved by increasing the heat of fusion. For example, in the conventional thermal spraying of Cu-5Sn powder, the heat of fusion was 30 kW in order to suppress oxidation, but if Cu-25% Sn powder with an increased Sn content is used, the heat of fusion will be oxidized even if the heat of fusion is 40 kW or higher There is no worry. That is, by changing the Sn content and performing thermal spraying at a higher temperature than before, for example, the surface fatigue strength can be set to 80 (MPa) or more which is a target value while maintaining the hardness at HV120 or less. Therefore, it is desirable that the heat of fusion be 30-50 kW.
4) A sprayed coating with high adhesion strength to the substrate can be formed.

  Generally, when the base material is preheated, the time for maintaining the liquid state after the molten particles collide with the surface of the base material becomes long, so that the adhesion strength with the base material is improved. However, since the thermal spray coating is easily oxidized in the conventional alloy, the preheating temperature of the base material cannot be increased. In this invention, the preheating temperature of a base material can be conventionally made high temperature by making a thermal spray powder into the material which is hard to oxidize. That is, it is possible to improve the film adhesion strength and the surface pressure fatigue strength while maintaining the film hardness low.

  FIG. 18 shows the relationship between the substrate preheating temperature and the adhesion strength of the thermal spray coating formed by thermal spraying of Cu-25% Sn alloy powder. As the substrate preheating temperature increases, the adhesion strength increases. In the conventional alloy powder of Cu-5% Sn, it was difficult to set the base material preheating temperature to 100 ° C. or higher. However, by increasing the Sn content, the base material preheating temperature can be made higher than before. I understand.

  FIG. 19 shows the relationship between the substrate preheating temperature and the surface pressure fatigue strength for a thermal spray coating formed by thermal spraying Cu-25% Sn alloy powder. Similar to the adhesion strength described above, the surface fatigue strength increases as the substrate preheating temperature increases. In the conventional alloy powder of Cu-5% Sn, it was difficult to set the base material preheating temperature to 100 ° C. or higher, so that only the surface pressure fatigue strength of the target value was obtained, but the Sn content should be increased. Since the substrate preheating temperature can be increased, higher surface pressure fatigue strength can be obtained.

That is, the preheating temperature of the substrate is desirably 200 to 300 ° C. in order to improve the film adhesion strength and the surface pressure fatigue strength while maintaining the film hardness low. .
5) Variation in hardness of the sprayed coating due to variation in substrate temperature can be suppressed.

  FIG. 20 shows the relationship between the substrate preheating temperature and the thermal spray coating hardness. The case of using a Cu-25% Sn alloy as the spray powder is indicated by Δ, the case of using a conventional Cu-5% Sn alloy is indicated by ▪, and the case of using copper powder as a reference is indicated by ◆. In either case, the film hardness increases as the substrate preheating temperature increases. However, it can be seen that the higher the Sn content, the lower the hardness. In particular, in the case of Cu-25% Sn alloy powder, the hardness increases in proportion to the base material preheating temperature, but the ratio is small. For example, the base material preheating temperature increases from 100 ° C to 300 ° C by 200 ° C. Even so, the hardness is only about HV30. Therefore, even if the base material preheating temperature varies, the hardness of the sprayed coating does not vary greatly.

That is, since the oxidation can be suppressed by increasing the amount of Sn, variations in film hardness due to preheating of the substrate can be suppressed.
6) The seizure resistance of the sprayed coating can be improved.

In the conventional bearing metal formed by sintering Cu—Sn alloy powder, the hardness of the bearing metal increases rapidly as the Sn content in the alloy powder increases, as shown by ■ in FIG. . This is presumably because CuSn intermetallic compounds such as Cu ₃₁ Sn ₈ and Cu ₄₁ Sn ₁₁ are partially formed in the bearing metal by sintering the alloy powder. For this reason, in the alloy powder material for bearing metal, the Sn content could not be increased.

However, since the thermal spray coating is formed by rapid solidification, it is considered that CuSn intermetallic compounds are hardly formed even with the same alloy composition, and the coating is hard to be cured even if the Sn amount is increased. Therefore, as shown in FIG. 22, Sn, which is a sliding component, can be increased to improve the seizure resistance.
7) The thermal spray coating can be thermal spray molded with low energy.

  In the Cu—Sn alloy, the melting point can be significantly lowered by increasing the Sn content. For example, the melting point of copper is about 1100 ° C., but the melting point of Cu—25% Sn alloy is about 800 ° C., which is extremely low. Therefore, the energy required for melting the thermal spray powder can be reduced as the Sn content is increased. If the melting point of the alloy powder can be lowered, it is difficult to form unmelted particles in the thermal spray coating even if the supply amount of the thermal spray powder is increased. Therefore, the number of times of thermal spray lamination (the number of times of spray gun passes) for forming the thermal spray coating is reduced. be able to. By reducing the number of times of thermal spray lamination, oxidation between the formed multilayers can be suppressed, and the oxidation amount of the entire thermal spray coating can be reduced.

  FIG. 23 shows the relationship between the number of sprayed layers of the sprayed coating formed by spraying Cu-25% Sn powder and the amount of oxidation in the coating. The formed film thickness was constant at 400 μm. It can be seen that the amount of oxidation in the sprayed coating is reduced by increasing the spraying amount per time and decreasing the number of laminations.

  Therefore, it is desirable that the thermal spray coating of the second invention is laminated as few times as possible.

  As described above, the thermal spray coating according to the second aspect of the present invention is a thermal spray coating formed by spraying a powder composed of 15 to 40% Sn by weight and the balance of copper and inevitable impurities on the surface of the substrate. is there. As already explained, if the Sn content is less than 15% by weight, or if the Sn content exceeds 40% by weight, the amount of oxidation in the sprayed coating increases and the hardness of the sprayed coating increases, which is not suitable. More preferably, the content of Sn in Cu is 20 to 35% by weight.

  The particle size of the Cu—Sn alloy powder is desirably 10 to 45 μm. If the particle size of the alloy powder is less than 10 μm, it is easy to melt, so that stable spraying cannot be obtained, and if it exceeds 45 μm, melting may be insufficient. More preferably, it is 20-35 micrometers.

  The thermal spray coating of the present invention desirably has an oxidation amount of less than 4%. If the oxidation amount exceeds 4%, the film is hardened, which is not preferable. More preferably, it is less than 1%.

  3rd invention of this invention is invention regarding the formation method of the sprayed coating which forms the sprayed coating of 1st invention.

  That is, the method for forming a thermal spray coating of the present invention is to form a thermal spray coating by spraying a mixed powder obtained by mixing 5 to 25% Sn and 95 to 75% by weight Al powder on the surface of a substrate. It is characterized by. Here, the formation method of the sprayed coating in this Embodiment is not specifically limited, It can carry out by a normal method. An example is described below.

  First, the surface of the substrate is shot blasted so that the surface has Rz = 40 to 60 μm. In order to improve the adhesion between the thermal spray coating and the substrate on the surface roughened by shot blasting, an intermediate layer is formed by a method such as plating, sputtering or thermal spraying. The thickness of the intermediate layer is preferably 100 to 150 μm. Next, a thermal spray coating of 350 to 400 μm is formed on the intermediate layer by spraying the thermal spray powder. Further, a desired finished film is formed by cutting or the like.

  Here, as the base material, various materials such as steel and aluminum can be adopted without limitation, but steel is preferable. The intermediate layer material is not particularly limited, and copper, nickel, aluminum, copper-nickel alloy, nickel-aluminum alloy, copper-aluminum alloy, nickel self-fluxing alloy, cobalt self-fluxing alloy, etc. should be used as appropriate. Can do.

  A plasma spraying method is desirable as the spraying method. FIG. 11 schematically shows an example thereof. The powder 14 supplied from the powder supply hose 13 into the plasma jet 12 is melted and sprayed onto the inner peripheral surface of the workpiece (for example, a bearing member) 15 by the plasma jet 12 ejected from the spray gun 11. . The spray gun 11 is held at an angle α with respect to the axis of the work 15 and rotates around the axis while maintaining the spray distance d and moving up and down parallel to the axis (arrow Y). A sprayed coating can be formed on the inner peripheral surface of the workpiece 15 that is being worked.

  Table 1 shows an example of suitable thermal spraying conditions for the mixed powder obtained by mixing the Al powder and the Sn powder according to the first invention of the present invention.

  4th invention of this invention is invention regarding the formation method of the sprayed coating which forms the sprayed coating of 2nd invention.

  That is, the method for forming a sprayed coating according to the present invention is to form a sprayed coating by spraying powder containing Sn and 40% by weight on the surface of the base material containing 15 to 40% by weight of Sn. Features. An example is described below.

  First, the surface of the substrate is shot blasted so that the surface has Rz = 40 to 60 μm. In order to improve the adhesion between the thermal spray coating and the substrate on the surface roughened by shot blasting, an intermediate layer is formed by a method such as plating, sputtering or thermal spraying. The thickness of the intermediate layer is preferably 100 to 150 μm. Next, on this intermediate layer, a powder containing 15 to 40% by weight of Sn, with the balance being made of copper and inevitable impurities is sprayed to form a sprayed coating of 350 to 400 μm. Further, the sprayed coating is subjected to cutting or the like to obtain a desired finished coating.

  Here, as the base material, various materials such as steel and aluminum can be adopted without limitation, but steel is preferable. The material of the intermediate layer is not particularly limited, and copper, nickel, aluminum, copper nickel alloy, nickel aluminum alloy, copper aluminum alloy, nickel self-fluxing alloy, cobalt self-fluxing alloy, etc. are appropriately used. be able to.

  A plasma spraying method is desirable as the spraying method. FIG. 11 schematically shows an example thereof. The powder 14 supplied from the powder supply hose 13 into the plasma jet 12 is melted and sprayed onto the inner peripheral surface of the workpiece (for example, a bearing member) 15 by the plasma jet 12 ejected from the spray gun 11. . The spray gun 11 is held at an angle α with respect to the axis of the work 15 and rotates around the axis while maintaining the spray distance d and moving up and down parallel to the axis (arrow Y). A sprayed coating can be formed on the inner peripheral surface of the workpiece 15 that is being worked.

  Table 2 shows an example of suitable thermal spraying conditions for the Cu—Sn alloy powder according to the second aspect of the present invention.

  In the thermal spray coating forming method of the present invention, it is desirable to preheat the substrate to 200 to 300 ° C. to form the thermal spray coating. By increasing the preheating temperature of the base material, it is possible to improve the contact pressure fatigue strength of the thermal spray coating and improve the adhesion strength with the base material.

  Moreover, in the formation method of the thermal spray coating of this invention, it is desirable for the heat of fusion which fuse | melts a thermal spraying powder to be 30-50 kW. By increasing the heat of fusion, the surface pressure fatigue strength of the thermal spray coating can be improved.

  Furthermore, in the method for forming a thermal spray coating of the present invention, the number of times the thermal spray coating is laminated is preferably one. By setting the number of times of the thermal spray coating to one, oxidation of the coating can be reduced and a good thermal spray coating can be obtained.

  The fifth invention of the present invention relates to a bearing member. That is, the bearing member of the fifth invention is a bearing member in which metal particles are sprayed on the surface of the base material to form a sprayed coating, and the metal particles are 5 to 25% Sn powder and 95 to 75 by weight percentage. It is a mixed powder obtained by mixing a weight percent of Al powder. A bearing member formed by spraying such a mixed powder to form a spray coating has high surface pressure fatigue strength and good seizure load, and therefore can be suitably employed as a connecting rod for an automobile internal combustion engine.

  The sixth aspect of the present invention relates to a bearing member. That is, the bearing member of the sixth invention is a bearing member in which metal particles are sprayed on the surface of the base material to form a sprayed coating, and the metal particles contain 15 to 40% Sn by weight, and the balance Is a powder composed of copper and inevitable impurities. A bearing member formed by spraying such a mixed powder to form a thermal spray coating has high surface pressure fatigue strength and good seizure load, and therefore can be suitably used as a connecting rod for an automobile internal combustion engine.

It is a cross-sectional schematic diagram of the sprayed coating formed by spraying the mixed powder of Al powder and Sn powder. It is a mapping image by EPMA of the sprayed coating formed by spraying the mixed powder of Al powder and Sn powder. a is a mapping image of AL and b is a mapping image of Sn. It is a figure which shows the relationship between the surface pressure fatigue strength by the amount of Sn powder of the thermal spraying coating formed by spraying the mixed powder of Al powder and Sn powder, and a seizure load. It is explanatory drawing explaining the bias | inclination of Sn in a thermal spray coating. It is explanatory drawing explaining the state which Sn disperse | distributed uniformly in the sprayed coating. It is a figure which shows the relationship between the particle size ratio of a mixed powder, and a dispersion rate. It is explanatory drawing explaining the definition of a dispersion rate. It is a comparison figure which compares the surface pressure fatigue strength of the sprayed coating formed with each powder. It is a figure which shows the hardness and dispersion | variation of the thermal spray coating by powder. It is a figure which shows the change of the high temperature hardness of a thermal spray coating. It is a schematic diagram which shows an example of the plasma spraying method. It is a cross-sectional schematic diagram of the sprayed coating formed by spraying Al-Sn alloy powder. It is a mapping image by the EPMA of the sprayed coating formed by spraying Al-Sn alloy powder. a is a mapping image of AL and b is a mapping image of Sn. It is a figure which shows the relationship between Sn content and oxidation amount of Cu-Sn alloy powder. It is a figure which shows the relationship between Sn content of Cu-Sn alloy powder, and the hardness of a sprayed coating. It is a figure which shows the relationship between Sn content of a Cu-Sn alloy powder, and the elongation rate of a sprayed coating. It is a figure which shows the relationship between the fusion heat of Cu-25% Sn alloy powder, and surface pressure fatigue strength. It is a figure which shows the relationship between the base-material preheating temperature of Cu-25% Sn alloy powder, and adhesion strength. It is a figure which shows the relationship between the base-material preheating temperature of Cu-25% Sn alloy powder, and surface pressure fatigue strength. It is a figure which shows the change of the thermal spray coating hardness by base-material preheating temperature. It is a figure which shows the relationship between Sn content of Cu-Sn alloy powder, and the hardness of a sprayed coating. It is a figure which shows the relationship between Sn content of Cu-Sn alloy powder, and the seizure resistance of a sprayed coating. It is a figure which shows the relationship between the thermal spraying lamination frequency and the oxidation amount of a thermal spray coating.

Explanation of symbols

1: Thermal spray coating 2: Al 3: Sn 4: Base material 11: Thermal spray gun 12: Plasma jet 13: Powder supply hose 14: Thermal spray powder 15: Workpiece

Claims (12)

It is a sprayed coating formed by spraying metal particles on the surface of a substrate,
The thermal spray coating, wherein the metal particles are a mixed powder in which 5 to 25% by weight of Sn powder and 95 to 75% by weight of Al powder are mixed.   The thermal spray coating according to claim 1, wherein the mixed powder has a particle size of 10 to 75 μm.   The thermal spray coating according to claim 1 or 2, wherein a particle diameter of the Sn powder with respect to a particle diameter of the Al powder is 0.5 to 0.8. It is a sprayed coating formed by spraying metal particles on the surface of a substrate,
The said metal particle contains 15 to 40% of Sn by weight percentage, The remainder is a powder which consists of copper and an unavoidable impurity, The thermal spray coating characterized by the above-mentioned.   The thermal spray coating according to claim 4, wherein the powder has a particle size of 10 to 45 μm.   The thermal spray coating according to claim 4 or 5, wherein an oxygen concentration in the thermal spray layer is less than 4% by weight.   A method for forming a sprayed coating, comprising spraying a mixed powder obtained by mixing 5 to 25% by weight of Sn powder and 95 to 75% by weight Al powder on a substrate surface to form a sprayed coating.   A method for forming a sprayed coating, comprising forming a sprayed coating by spraying a powder containing Sn and 15 to 40% by weight, the balance being copper and inevitable impurities, onto a substrate surface.   The method for forming a sprayed coating according to claim 8, wherein the substrate is preheated to 200 to 300 ° C.   The method for forming a thermal spray coating according to claim 9, wherein the thermal spray coating is laminated once. A bearing member in which metal particles are thermally sprayed on a substrate surface to form a sprayed coating,
The bearing member according to claim 1, wherein the metal particles are a mixed powder in which 5 to 25% by weight of Sn powder and 95 to 75% by weight of Al powder are mixed. A bearing member in which metal particles are thermally sprayed on a substrate surface to form a sprayed coating,
The said metal particle contains 15 to 40% of Sn by weight percentage, The remainder is a powder which consists of copper and an inevitable impurity, The bearing member characterized by the above-mentioned.

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