JP3501194B2 - Spray method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for spraying a thermal spray material such as metal or ceramic on the surface of a substrate.

[0002]

2. Description of the Related Art For example, in order to obtain a material having excellent wear resistance, etc., a sprayed coating is formed on the surface of the base material with a thermal spray material having excellent wear resistance such as metal or ceramic. There is a method of modifying. In this case, the spray coating is
It is usually formed to a thickness of 100 to 500 μm.

Conventionally, as a method of performing thermal spraying treatment on a base material, a spray gun is used to spray a particulate thermal spray material (sprayed particles) in a molten state onto the surface of the base material, and then onto the surface of the base material. A method of forming a thermal spray coating by solidifying laminated thermal spray materials is known. In this method, the above 100
In order to obtain a coating with a thickness of up to 500 μm, the coating thickness is usually secured by performing thermal spraying treatment several times.

[0004]

However, the above-mentioned conventional thermal spraying method has the following problems. That is, the thermal spray coating obtained by the above-mentioned conventional thermal spraying method may cause cracking or peeling at an early stage, and may not be able to exhibit a sufficient surface modifying effect. It is considered that this is due to the following reasons.

That is, the thermal spray material sprayed on the base material is rapidly cooled and solidified by heat radiation to the base material. At this time, the thermal spray material causes solidification shrinkage. Therefore, residual stress in the tensile direction is generated inside the formed sprayed coating due to the stress due to the solidification shrinkage. Therefore, it is considered that the properties such as strength of the sprayed coating itself are deteriorated and the adhesion between the sprayed coating and the base material is decreased.

Further, when the thermal spray coatings are stacked in layers by a plurality of thermal sprays in the air atmosphere, the coating surface of each layer is oxidized in the process of coating formation. Therefore, the thermal spray coating is formed with the oxide sandwiched between the layers. Therefore, it is considered that a problem occurs in the adhesiveness and the like inside the sprayed coating formed by stacking, and the characteristics such as strength of the sprayed coating itself further deteriorate.

As a method for improving the adhesion between the thermal spray coating and the base material against such problems, before performing the thermal spray treatment,
A method is known in which a blast treatment is carried out in which small blast particles collide with a substrate at a high speed in advance, whereby the surface roughness of the substrate surface before thermal spraying is roughened to activate the substrate surface.

However, according to this method, although the adhesion between the base material and the thermal spray coating is slightly improved, tensile residual stress occurs in the thermal spray coating as in the above case. In addition, the presence of the oxide layer inside the coating reduces the properties such as strength of the thermal spray coating itself. Therefore, as a result, there is a problem that the effect of surface modification such as abrasion resistance is small.

As a method for improving the characteristics of the sprayed coating, there is a method of spraying in a reduced pressure atmosphere. However, in the case of this method, there is a problem that the cost is increased and the productivity is lowered because the reduced pressure atmosphere is formed. Therefore, the merit of applying it to actual production is low.

Another method is, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 136504, there is a method of sequentially blasting the sprayed surface immediately before spraying in synchronization with the spray gun. In this method, the surface of the base material can be activated, the problem of rebounded thermal spray particles adhering to the surface of the base material can be solved, and the characteristics of the thermal spray coating can be slightly improved. However, the above problem of tensile residual stress is not fundamentally solved.

Yet another method is, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 4-16341, a method of performing shot peening treatment simultaneously with thermal spraying in an inert gas atmosphere has been proposed. According to this method, the thermal spray coating that is being formed is subjected to hot working treatment, which has some effect in reducing the above-mentioned tensile residual stress, and the characteristics of the thermal spray coating can be slightly improved. However, in this case, since the sprayed particles collide with the base material in a molten state at the same time as the peening particles, there is a problem that the peening particles easily enter the sprayed coating, which causes deterioration of coating properties. Inevitable.

The present invention has been made in view of the above conventional problems, and is excellent in the adhesion between the thermal spray coating and the substrate and the characteristics of the thermal spray coating itself, and can exhibit a sufficient surface modifying effect.
It is intended to provide a thermal spraying method.

[0013]

According to the invention of claim 1, a plurality of times of thermal spraying is performed.
A thermal spraying method in which thermal sprayed coatings are further stacked in layers, wherein thermal sprayed particles are sprayed on the surface of a base material to form the thermal sprayed coating,
Next, the surface of the thermal spray coating is blasted with blast particles , and then the blast treatment is applied to the thermal spray coating.
The above-mentioned thermal spraying and the above-mentioned blast treatment are repeated multiple times on the surface of the film.
And then the blast treatment is performed on the thermal spray coating.
The temperature is 25 to 9 of the final solidification temperature (Celsius) of the spray particles.
The thermal spraying method is characterized in that the thermal spraying is performed while it is within the range of 9% .

What is most noticeable in the present invention is that after forming the above-mentioned thermal spray coating,
The above is to perform the blast process. The above thermal spray processing is
As in the conventional method, the spraying gun is used to spray the sprayed particles onto the substrate surface. Further, as the spray particles,
For example, particles of various materials such as Fe-Cr-C alloy, Al-Si alloy, Ni-based alloy, Cu-based alloy, Mo, or composite materials of these and ceramic powder (Cr ₂ O ₃ , Al ₂ O ₃ etc.) To use.

The above-mentioned blast treatment is a treatment in which minute blast particles collide with the surface of the base material at high speed, and can be performed using a blast gun. The blast treatment is performed at least after the spray particles have solidified to form a coating. Further, as will be described later, it is preferable to perform the blast treatment while each thermal spray coating is within a certain temperature range, depending on the type of thermal spray particles.

Next, the operation of the present invention will be described. In the present invention, as described above, after the sprayed coating is formed by the spraying treatment, the blasting treatment is performed on the sprayed coating. Therefore, stress is applied to the thermal spray coating in the thickness direction of the coating due to the collision of the blast particles, and plastic deformation is applied in the direction parallel to the coating surface.

This plastic deformation can alleviate or eliminate the tensile residual stress generated inside the thermal spray coating due to solidification shrinkage. That is, in the blasting treatment after the formation of the thermal spray coating, the residual stress in the thermal spray coating can be controlled arbitrarily, whereby the adhesion between the thermal spray coating and the substrate and the characteristics of the thermal spray coating itself can be measured before the blast treatment. Significantly improved compared to.

When the thermal spraying process is performed a plurality of times to form a thermal sprayed film having a predetermined thickness, the surface of the film formed by the thermal spraying process at each time is sequentially blasted at each time. Therefore, oxides and the like are removed from the surface of the thermal sprayed coating after thermal spraying, so that the surface is always in an active state, and a large amount of oxide does not exist between the surface and the thermal sprayed coating. Therefore, the properties such as strength of the sprayed coating itself are further improved. Therefore, it is possible to perform the thermal spraying treatment which is excellent in the adhesion between the thermal spray coating and the substrate and the characteristics of the thermal spray coating itself, and which can exert a sufficient surface modification effect.

Blasting may be performed before or after the thermal spraying. In this case, the activation effect on the surface before thermal spraying is further improved, and the characteristics of the thermal spray coating are further improved.

[0020] Next, the blasting 25 of the final solidification temperature (degrees Celsius) of the temperature of the thermal spray coating the spray particles
~ Within 99% range . In addition, by thermal spraying,
The temperature drops from a state where the spray particles are completely melted, and a solid-liquid coexisting state is established. The lower limit temperature of this solid-liquid coexisting state is the final solidification temperature. For example, Fe-Cr-
When the C alloy is used as the spray particles, the final solidification temperature is 1440 ° C., so the blast treatment is performed while the temperature is within the range of 25 ° C. 360 ° C. to 99% 1426 ° C.

Here, the above temperature range means a region in the vicinity of a temperature at which the thermal spray coating is likely to be plastically deformed and recrystallization occurs after the plastic deformation. When the blast treatment is performed at a temperature higher than the above temperature range (temperature exceeding 99% of the final solidification temperature), there is a problem that the compressive stress due to the blast treatment is not applied because of the solid-liquid coexisting state.

On the other hand, when the blast treatment is carried out at a temperature lower than the above temperature range (temperature less than 25% of the final solidification temperature), the plastic deformation of the coating becomes difficult, and cracking or breakage of the coating occurs. There is a problem of fear.

[0023] In addition, the average particle size of the blast particles,
It is preferably in the range of 20 to 500 μm. When the average particle diameter is less than 20 μm, there is a problem that effective stress cannot be applied to the thermal spray coating and the tensile residual stress cannot be sufficiently relaxed, and preferably 30 μm or more. On the other hand, when the average particle diameter exceeds 500 μm, the stress applied to the thermal spray coating becomes too local, and there is a problem that the residual tensile stress cannot be removed uniformly. It is preferably 300 μm or less.

[0024]

Embodiment 1 Embodiment 1 A thermal spraying method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. In this example, as shown in FIG. 4, an aluminum alloy test piece (JIS6061 alloy, length 200 m)
m, width 60 mm, thickness 10 mm) is used as the base material 9,
A thermal spray coating 8 made of Fe-Cr-C alloy was formed on the surface.

First, the thermal spraying device 1 will be described with reference to FIG. As shown in FIG. 2, the thermal spraying device 1 includes a thermal spraying gun 10 and two blasting guns 21 arranged before and after the thermal spraying gun 10.
22 and these are integrally provided so as to be reciprocally movable in the left-right direction. And the blast guns 21, 22
Is configured so that it can be switched between operation and stop on its forward or return path.

Further, the spray gun 10 and the blast gun 21,
As shown in FIG. 2, the distance between the nozzles 22 and 22 is such that the distances L ₁ and L ₂ between the centers of the openings at the tips of the guns are 40 mm, respectively. In addition, each gun 10, 21, 22
The distance L ₃ between the tip of the base material and the base material 9 is 100 mm. Also, the spray angle R _{1 of the} spray gun 10
Is set to 90 ° in the vertical direction with respect to the base material 9, while the injection angle R ₂ of the blast guns 21 and 22 is 85 ° with respect to the base material 9 in the direction away from the spray gun 10.
The angle is set to.

Next, the spraying conditions and the like are shown below. Plasma output: 30 kVA (current 1000 A, voltage 30)
V), gas for plasma; Ar (argon) (36 liters /
Min), sprayed particles; Fe-Cr-C alloy (Cr 50-60%, C
2-5%, residual Fe), spraying particle supply amount; 30 g / min, spraying distance; 100 mm,

Next, the blast conditions and the like are shown below. Blast particles: Spherical alumina, Blast particles average particle size: 100 to 200 μm (Average particle size (50 μm)), Blast injection angle: 85 °, Injection pressure: 5 kgf / cm ² , Blast particle average speed: 70 m / sec,

Next, the procedure for actually forming a thermal spray coating using the thermal spray apparatus 1 under the above conditions will be described.
First, as a method of using the thermal spraying apparatus 1, as shown in FIG. 1 (a), for example, when the thermal spraying process proceeds to the right in the same figure, the front blast gun 21 is stopped and the thermal spray particles 21 are stopped. Only the blast gun 22 on the rear side of the thermal spray gun 10 for injecting 109 is operated to blast particles 29.
Inject.

Further, as shown in FIG. 1 (b), when the thermal spraying process is advanced to the left, which is the opposite of the above, the blast gun 22 at the head of the advancing direction is stopped and the rear side Only the blast gun 21 is actuated to blast with the blast particles 29. As a result, when the thermal spraying device 1 is reciprocally moved to form the thermal spray coating 8,
A blast treatment can always be performed after forming the thermal spray coating 8.

Next, the timing of the blast process will be described with reference to FIG. FIG. 3 shows the cooling curve C of the thermal spray coating, with the horizontal axis representing time and the vertical axis representing temperature. That is,
As shown in FIG. 3, in the blast treatment, the temperature of the sprayed coating is the final solidification temperature T ₀ (1440) of the Fe—Cr—C alloy.
Blasting treatment is performed within a recrystallization temperature range S of 25% temperature T ₂ (360 ° C.) to 99% temperature T ₁ (1426 ° C.).

Specifically, as shown in FIG. 3, according to the cooling curve C of the sprayed coating measured in advance, after a certain time has elapsed from the time of spraying (A ₀ ), the range of time A ₁ -A ₂ (B ), The temperature of the thermal spray coating is found to be within S within its recrystallization temperature range. Therefore, the spraying gun 10 and the blast guns 21 and 22 are integrally moved at the constant interval at a constant speed, so that the optimum timing of the blasting process can be secured. The transfer speed of the thermal spraying device 1 in this example is 600 mm / sec. It is also possible to adopt a method in which a two-color thermometer or the like for measuring the temperature of the spray coating is provided in the spray apparatus 1 and the blasting timing is controlled based on the measured temperature.

Under the above conditions, as shown in FIG. 4, the thermal spraying and blasting treatments were repeated about 20 to 30 times with respect to the base material 9 to form the thermal spray coating 8 having a thickness of 0.4 mm. next,
In order to investigate the properties and the like of the obtained thermal spray coating 8, the thermal spray coating 8
The residual stress inside, the adhesion strength between the thermal spray coating 8 and the substrate 9, and the coating strength of the thermal spray coating 8 were measured.

As shown in FIG. 4, the residual stress was measured from the outermost surface of the sprayed coating on the substantially central portion D ₁ of the base material 9 by the X-ray diffraction method. As for the adhesion strength and the film strength, as shown in FIG. 5, a test piece 8 was prepared by vertically cutting the vicinity of the residual stress measuring portion (D ₁ ) into a thickness of 1 mm.
Shear test was performed on the interface portion D ₂ between the thermal spray coating 8 and the base material 9 and the portion D ₃ of 1/2 of the thermal spray coating thickness, and the obtained shear strength was evaluated.

Table 1 shows the residual stress of the sprayed coating 8, the adhesion between the substrate 9 and the sprayed coating 8, and the coating strength of the sprayed coating 8 together with the results of Comparative Examples 1 and 2 described later.

COMPARATIVE EXAMPLE 1 In this comparative example, the thermal spraying apparatus 1 according to the first embodiment is used.
Using the base material 9 and the blast guns 21 and 22, the operating state was reversed from that of the first embodiment. That is, as shown in FIG. 6A, when the thermal spraying process is advanced to the right in the figure,
Activate the top blast gun 21, while spraying gun 10
The blast gun 22 on the rear side of is stopped.

Further, as shown in FIG. 6 (b), when the thermal spraying process is performed in the opposite direction to the above, the blast gun 22 at the head is in the operating state, while the blast gun 21 on the rear side is in the stopped state. To do. As a result, when the thermal spraying process is performed back and forth, the blasting process is always performed just before the thermal spraying process. Others are the same as those in the first embodiment.

With respect to the thermal spray coating obtained in this example, the residual stress, the adhesion between the base material and the thermal spray coating, and the coating strength of the thermal spray coating were measured in the same manner as in the first embodiment. The results are shown in Table 1.

Comparative Example 2 In this comparative example, as shown in FIG.
Blast gun 2 using the thermal spraying device 1 and the base material 9 in
No. 1 and No. 22 were always stopped, and thermal spraying was performed without performing any blasting. Others were the same as those in the first embodiment. With respect to the thermal spray coating obtained in this example, the residual stress, the adhesion between the base material and the thermal spray coating, and the coating strength of the thermal spray coating were measured in the same manner as in the first embodiment. The results are shown in Table 1.

As can be seen from Table 1, the embodiment 1 in which the blasting treatment is carried out immediately after the thermal spraying treatment has a very good internal structure in which the residual stress in the tensile direction in the thermal spray coating disappears and a slight compressive stress remains. You can see that it is in a state. In addition, the adhesive strength and coating strength also showed very good performance.

On the other hand, in Comparative Example 2, a large tensile stress remained, and the adhesion strength and the film strength were also the worst. In Comparative Example 1, all of them are slightly improved as compared with Comparative Example 2, and although the effect of the blast treatment before thermal spraying appears, the improvement effect is much lower than that of Embodiment 1.

As described above, performing the blasting treatment on the surface after forming the thermal spray coating makes the thermal spray coating adhere to the substrate more closely than when performing the blasting treatment immediately before the thermal spraying or when not performing the blasting treatment. It can be seen that there is a great effect in improving the force and the properties of the sprayed coating itself.

[0043]

[Table 1]

Embodiment 2 In this embodiment, 2 of the thermal spraying device 1 in Embodiment 1 is used.
Both blast guns 21 and 22 are always activated,
Blasting was performed before and after the thermal spraying. Others are the same as those in the first embodiment.

In this example, the adhesion between the base material and the thermal spray coating and the characteristics of the thermal spray coating were slightly improved as compared with the first embodiment. It is considered that this is because the effect of the blasting process immediately before thermal spraying of Comparative Example 1 was added to the effect of the blasting process after thermal spraying of Embodiment 1.

[0046]

As described above, according to the present invention, there is provided a thermal spraying method which is excellent in the adhesion between the thermal spray coating and the substrate and the characteristics of the thermal spray coating itself, and which can exhibit a sufficient surface modifying effect. You can

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing processing states in (a) an outward path and (b) a return path in the first embodiment.

FIG. 2 is an explanatory diagram showing a configuration of a thermal spraying device according to the first embodiment.

FIG. 3 is an explanatory view showing a region of a cooling curve of a sprayed coating and an optimum blast treatment timing in the first embodiment.

FIG. 4 is an explanatory view showing a state in which a thermal spray coating is formed on the surface of the base material in the first embodiment.

FIG. 5 is an explanatory view showing a test piece for evaluating the characteristics of a sprayed coating in the first embodiment.

6A and 6B are explanatory diagrams showing processing states in (a) a forward path and (b) a return path in Comparative Example 1. FIG.

FIG. 7 is an explanatory diagram showing a processing state in Comparative Example 2.

[Explanation of symbols]

1. ． ． Thermal spray equipment, 10. ． ． Spray gun, 109. ． ． Spray particles, 21,22. ． ． Blast gun, 29. ． ． Blast particles, 8. ． ． Spray coating, 9. ． ． Base material,

Front Page Continuation (72) Hiroyuki Mori Inventor, Hiroyuki Aichi Prefecture, Nagakute-cho, Aichi, Japan 1-41 Yokomichi, Yokomichi Toyota Central Research Institute Co., Ltd. (56) Reference JP-A-53-6238 (JP, A) 4-346626 (JP, A) JP-A-6-136504 (JP, A) JP-A-54-16341 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 4/12 C23C 4/18

Claims (2)

(57) [Claims] 1. A thermal spray coating is layered by a plurality of thermal sprays.
A thermal spray method overlaying seen, the by spraying the sprayed particles on the surface of the substrate to form the thermal spray coating, then the surface of the solution morphism coating blasting by blasting particles, then, subjected to the blast treatment Surface of thermal spray coating
In addition, the above spraying and blasting treatments were repeated multiple times.
In addition, the temperature of the thermal spray coating is above the blast treatment.
Range of 25 to 99% of final solidification temperature (Celsius) of spray particles
Spraying method characterized by being performed while inside . 2. The thermal spraying method according to claim 1, wherein the blast particles have an average particle size in the range of 20 to 500 μm.