JPS5811261B2 - Method for forming thermal spray coating containing solid lubricant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a thermal spray coating containing a solid lubricant, and more specifically, for example, on the sliding friction surface of equipment, boron nitride, molybdenum disulfide, tungsten disulfide, graphite, etc. The present invention relates to a method for forming a thermal spray coating having lubricity containing a solid lubricant.

As a means of applying lubricant to the required parts of equipment, generally the above-mentioned solid lubricant is applied to the surface of the core, or solid lubricant powder is applied to powder of plastics, metals, ceramics, etc. A method is adopted in which the components of the device are manufactured by mixing the components and compression molding or sintering the mixture.

However, in the former case, if the lubricant is not replenished at an appropriate time, the lubricant film formed on the surface will break and cause severe wear and adhesion, and in the latter case, the entire device will be damaged. Since the solid lubricant is dispersed and interposed in unnecessary locations, it is wasteful and has the disadvantage of significantly deteriorating the mechanical strength of the parts.

This invention was researched and developed to eliminate the above-mentioned drawbacks.In order to solve this problem, it is necessary to form a film on the surface of the sliding parts of equipment with a solid lubricant uniformly distributed in three dimensions. At the same time, we focused on the fact that thermal spraying is a simple and effective way to form such a film.On the other hand, solid lubricants undergo oxidation reactions in the atmosphere due to high temperatures; Even if thermal spray material powder containing additives is sprayed using a normal jet spraying method, it will oxidize and deteriorate due to high temperatures, and the amount of dripping will significantly decrease due to combustion, making it impossible to obtain a film with the desired good lubricity. This is based on the recognition that when a thermal spray coating is formed by a jet thermal spraying method such as plasma spraying, arc thermal spraying, or combustion gas thermal spraying, the main thermal spraying material and solid lubricant powder that serve as the base are used as the thermal spraying material. , a method for forming a thermal spray coating containing a solid lubricant, characterized in that the solid lubricant powder is supplied into the thermal spray jet from a forward position separated by at least 5 m/m from the tip of a torch to form a thermal spray coating. This is related.

That is, as shown schematically as an example of the method of adding solid lubricant to A (plasma spraying), B (wire or rond type combustion gas spraying), and C (powder type combustion gas spraying) in Fig. 1, oxidation of the solid lubricant is performed. In order to prevent quality deterioration and yield reduction, a special supply point for lubricant powder is installed separately from the main thermal spraying material that serves as the base, and a relatively low-temperature part ( Solid lubricant powder is supplied to the front position (away from the tip of the torch) and delivered to the target surface together with the main thermal spraying material, forming a thermal sprayed coating in which the solid lubricant is dispersed in the base formed of the main thermal spraying material. In the figure, 1 is a thermal spraying torch, 2 is a thermal spraying flame, 3 is a main thermal spraying material powder supply nozzle (only in Figure A), 4 is a main thermal spraying material, and 5 is a solid lubricant powder 6. A supply nozzle, 7 a thermal spray jet, 8 a formed thermal spray coating, 9 a surface of a thermal spray object, and 10 a main thermal spray material (powder) supply hopper (FIG. C only).

This invention can be effectively applied to all thermal spraying methods that use gas jets, such as plasma spraying, arc spraying, and combustion gas spraying (powder type, wire set, Rondo type), and the solid lubricant powder is nitrogen, The solid lubricant powder is transported through the hose by an inert gas such as argon gas, and is injected into the thermal spray jet through the supply nozzle placed at a predetermined position.The center position of the nozzle hole tip of the solid lubricant powder supply nozzle is The range shown in FIG. 2 is appropriate.

That is, in Fig. 2, A indicates the thermal spraying torch, the mouth indicates the nozzle hole of the torch, and X indicates the direction of the thermal spray jet between the tip of the thermal spraying torch and the nozzle hole tip center position P of the solid lubricant powder supply nozzle. The distance Y indicates the distance between the jet direction center line of the thermal spray jet and the nozzle hole tip center position P. In the relationship shown in Table 1 below, if X<Ll, the lubricant The lubricant is supplied to the high-temperature part of the thermal spray flame and is oxidized and deteriorated at high temperature.If , even if it reaches the surface to be thermally sprayed, it does not come into close contact with the surface and the amount of small drips decreases.

In addition, when Y<Dl, the nozzle tip disturbs the streamlines of the thermal spray jet, causing the sprayed material to scatter and disappear and the adhesion strength of the thermally sprayed coating to decrease, and when Y>D2, the thermal spraying of the lubricant The feed rate into the jet is reduced and the droplets are reduced.

Therefore, the appropriate arrangement range of the center position P of the nozzle hole tip of the solid lubricant powder supply nozzle is the circumferential area shown by diagonal lines in FIG.

Example 1 Next, examples of this invention will be described.

(1) Object to be coated with thermal spray coating Spindle bearings in hot rolling equipment at steel plants.

The intermediate sliding bearing of the active power shaft (spindle) for driving rolls in hot rolling equipment has conventionally been made of Cu-Ni alloy and lubricated with grease, but due to severe wear, it has been replaced approximately every six months.

In order to improve the service life of this sliding bearing, the method of the present invention is applied. In Fig. 3, A shows the sliding bearing metal, and B shows the thermal sprayed coating layer containing solid lubricant formed on the bearing surface. It is.

(2) Construction conditions (a) Equipment; Plasma spray equipment (b) Thermal spraying material; Main spraying material...Lead bronze wire (3-
2m/m$) (10%5n- 10%Pb-80%Cu) Solid lubricant powder...Graphite (200-400Mesh) (c) Thermal spraying conditions: Plasma gas N2-H2 (4:1)5
0A/min Voltage, current 70V, 500A Spraying distance 120m/m) Solid lubricant supply nozzle hole position: X = 70m/m Y = 30m/m (based on the display format in Figure 2) (e) Solid lubrication Hole diameter of the agent supply nozzle, 2~(F) Thermal spray material supply amount; Lead bronze (10%5N-10%Pb-80%Cu) 8kg/lhr Graphite 1kg/1hr (g) Thermal spray coating layer; 1.0% ( 3) Spraying results As a result of analyzing the sprayed coating, the amount of graphite in the sprayed coating was 35V.
o1%, the small drip in this case was about 70%.

(Note) 5n-Pb- mixed with graphite without using illegal methods
The amount of graphite dripping during thermal spraying of Cu alloy does not even reach 5vol%.

(4) Effects of thermal spray coating formation After the thermal spray coating was formed, it was polished and used as the above-mentioned sliding bearing, and its service life was significantly improved to approximately 3.2 years, which was significantly higher than that of the conventional bearing. The service life is about 6 times that of metal sliding bearings.

Example 2 (1) Object for thermal spray coating Mandrel shaft of a tension reel in a hot rolling mill of a steel mill.

This part is used to expand the diameter of the take-up reel for hot-rolled steel sheets. By moving the mandrel shaft in the left-right direction, the reel diameter is expanded or contracted to take up the steel sheet and the wound product (coil). ), but when the spreader slides, especially when the reel diameter is shortened, the contact surface with the segment will wear out due to large frictional force as it slides against the tightening force of the coil. and cannot hold the segment in place.

In order to prevent wear of the mandrel shaft, the method of the present invention is applied to the contact surface, and in FIG. This shows the film layer.

(2) Construction conditions (a) Equipment; Combustion gas type metal wire thermal spraying equipment (0) Thermal spraying material; Main thermal spraying material...Aluminum bronze (9%A7-1%Fe-
Residual Cu) 32m/mO wire solid lubricant...Molybdenum disulfide (250-400Mes
h) and Boron nitride (250 to 400 MeSh) used individually with aluminum bronze wire (c) Thermal spraying conditions; Gas used: Oxygen, secondary gas pressure and flow rate during acetylene ignition... Oxygen 2 kg/cm2,251/min , Acetylene 1kg/cm2,251/min Air pressure and flow rate...4kg/cm2,251/min Spraying distance...200m/
m) Position of the solid lubricant supply nozzle hole; Thermal spray material supply amount: Aluminum bronze 8 kg/hr Molybdenum disulfide 2 kg/hr Boron nitride 1.2 kg/hr The amount of lubricant is
In the case of molybdenum disulfide, it is 26Vo1%, and in the case of boron nitride, it is 27Vo1%, and the yield in this case is:
It was about 75% for the former and about 70% for the latter.

(4) Effects of thermal spray coating formation After the thermal spray coating was formed, it was polished and used in actual equipment, and its service life was extended as follows.

Molybdenum disulfide additive coating: 24 months Boron nitride additive coating: 18 months This service life is 1.5 months longer than the approximately 12 months that would occur if normal thermal spraying measures were taken (spraying only aluminum bronze). It is extended by 5 times to 2 times, indicating that both molybdenum disulfide and boron nitride are extremely effective.

In addition, if no thermal spraying measures are taken (material 5F60)
) require replacement or repair every 3 to 6 months.

Example 3 (1) Object to be coated with thermal spray coating Axle box slide plate of slag pan truck at steelworks.

This part is a slide plate for holding the position of the axle box that stores the wheel bearings of the slug pan truck, and the axle box and the slide plate move relative to each other in the vertical direction due to vibrations when the truck is running. Since the slide plate holds the axle box in the horizontal direction, its contact surface slides in the vertical direction and wears out, and if a gap that exceeds the tolerance is created between the two, the slide plate must be replaced.

The useful life of this slide plate is usually about 12 months,
The method of the present invention is applied to the contact surface in order to prevent wear and tear, extend its lifespan, and reduce the number of man-hours required for replacement.
In the figure, A indicates the slide plate, and B indicates the thermal spray coating layer formed on the surface of the slide plate that comes in contact with the axle box.

(2) Construction conditions (a) Equipment; Combustion gas type metal wire thermal spraying equipment (0) Thermal spraying materials; Main thermal spraying materials...13 chromium steel (C0, 23%).

Cr], 2.6%) 3.2m/mm wire solid lubricant...tungsten disulfide (250-400Mech) (c) Thermal spraying conditions; same as Example 2) Position of solid lubricant supply nozzle hole; X= 100m/m Y-20m/m (based on the display format in Figure 2) (E) Hole diameter of solid lubricant supply nozzle; 2% (F) Spraying material supply amount; 13 Chrome steel 8kg/hr Tungsten disulfide 2. 4kg/hr (g) Thermal sprayed coating layer; 3m/m (3) Thermal spraying results As a result of analyzing the thermal sprayed coating, the volume fraction of tungsten disulfide in the coating was approximately 22Vo1%, and the yield was approximately 85%.

(4) Effect of thermal spray coating formation After the thermal spray coating was formed, it was polished and used in actual equipment, and its service life was 3.5 years.

This number of lives is when no thermal spraying measures are taken (Material 5S41)
This is 3.5 times longer than the 1.5 years of service life when only 13 chromium steel is sprayed, and the remarkable effect of the tungsten disulfide-added spray coating was seen.

As detailed above, according to the present invention, the adhesion strength and small dripping of the solid lubricant in the thermal spray coating can be maintained extremely well, and deterioration due to oxidation can be prevented as much as possible. By applying it to the sliding surfaces of similar parts and forming a sprayed coating layer on the face, the service life of the face can be significantly improved, and the desired lubrication effect can be maintained for a long period of time. It's something you get.

[Brief explanation of drawings]

A, B, and C in FIG. 1 are respectively schematic diagrams of examples of solid lubricant supply modes according to the present invention, and FIG. 2 is an explanatory diagram showing the appropriate arrangement range of the center position of the tip of the solid lubricant powder supply nozzle hole. Figures 3 to 5 show examples to which the present invention is applied. Figure 3 is a perspective view of a sliding bearing, Figure 4 is a perspective view of a part of a mandrel shaft, and Figure 5 is a shaft of a slag pan truck. It is a perspective view of a box slide board. 1...Torch, 4...Main thermal spray material, 6...Solid lubricant powder, 7...Thermal spray jet, 8...Thermal spray coating.

Claims (1)

[Claims] 1. When forming a thermal spray coating by a jet thermal spraying method such as plasma spraying, arc thermal spraying, or combustion gas thermal spraying, a main thermal spraying material serving as a base and a fixed lubricant powder are used as the thermal spraying materials, and at least this solid lubricant powder is used as the thermal spraying material. A method for forming a thermal spray coating containing a solid lubricant, characterized in that the solid lubricant is supplied into a thermal spray jet from a forward position spaced at least 5X from the tip of a torch to form a thermal spray coating.