JPH04120260A - Method for thermally spraying powdery material - Google Patents

Abstract

PURPOSE:To improve thermal spraying efficiency and to prevent the intrusion of impurities at the time of thermally spraying a powdery material on the surface of a base stock having a different thermal expansion coefficient by using a cored wire obtained by sealing the powdery material into a hoop to carry out thermal spraying. CONSTITUTION:A voltage is impressed on the electrode 2 and nozzle 3 of a plasma spraying gun 1 to inject a plasma jet 4 on the surface of a base stock 9, and a cored wire 5 is supplied into the plasma jet 4 by a feed roller 6. The wire 5 is obtained by sealing a powdery material 5b into a hoop 5a having a specified diameter and forming the hoop into a long wire, and the thermal expansion of the sprayed film is appropriately set by changing the ratio of the compositions and volumes of the hoop 5a and powdery material 5b. The wire 5 melted by the jet 4 is converted into the flying molten particle 8 at high temp. and speed, the particles collide with and firmly attach to the surface of the base stock 9 to form a buffer film 10, and a sprayed film 11 is formed on the surface. The sprayed film 11 of a desired mixing ratio is uniformly formed in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for spraying powder spray materials.

[Conventional technology]

Conventionally, in order to impart corrosion resistance and wear resistance to the surface of a metal material, when spraying a metal material or oxide material such as ceramics that has corrosion resistance and wear resistance onto the surface of the material to form a thermal spray coating, it is necessary to When the difference in thermal expansion coefficient between the two is large, such as when thermally spraying ceramics onto a material, a buffer film band must be provided to prevent the thermally sprayed film from cracking or peeling. As shown in the figure, thermal spraying methods using powder materials have been widely used.

That is, in FIG. 3, a voltage is applied between the electrode 2 and nozzle 3 of the plasma spray gun 1 to eject a plasma jet 4 from the nozzle 3, and at the same time, the powder material 13 placed in the hopper 12 is fed. By feeding the powder material 13 to the nozzle 3 through the pipe 14, the plasma jet 4 turns the powder material 13 into high-temperature, high-velocity flying molten particles 8, and the material 9
In addition to adhering to the surface to form a buffer coating 10, a thermal spray coating 11 is also formed on the surface. However, this buffer film 10
In forming the layer, the component ratio of the powder material is changed for each layer so that the coefficient of thermal expansion changes gradually from the material 9 to the sprayed coating 11.

However, with this method, the following dissatisfaction and
There is a case.

(1) It is necessary to take the three powder materials into and out of the powder material storage on-bar for each process, which makes the work cumbersome and causes a decrease in work efficiency. Furthermore, if the number of processes involving powder materials increases, there is a risk of contamination with impurities.

(2) Powder material is supplied to the thermal spray gun by being fed through a powder material feed pipe by gas pressure, but this method has a limit to the amount of feed and is not suitable for large-volume thermal spraying.

(3) Depending on the components of the powder material and the size of the particles, troubles such as clogging may occur in the powder material feeding system.

(4) When mixed powder materials are used, the mixing ratio changes during feeding due to the difference in specific gravity of each powder, making it difficult to obtain a uniform thermal spray coating.

[Problem to be solved by the invention]

The present invention was proposed in view of these circumstances, and
By turning the powder material into a wire thermal spray material, it is easier to handle, improving work efficiency, there is less risk of contamination with impurities, and the thermal spray material can be continuously fed to the thermal spray gun. It is an object of the present invention to provide a thermal spraying method for a powder thermal spray material, which allows large quantities of thermal spraying to be carried out, and which can obtain a thermal sprayed coating with a mixing ratio according to the purpose, and which can also provide a uniform thermal sprayed coating without changing the mixing ratio during feeding. purpose.

[Means to solve the problem]

To this end, the present invention is characterized in that when spraying a powder spray material onto the surface of a material that has a coefficient of thermal expansion different from that of the powder spray material, a cored wire in which the powder material is enclosed in a hoop is used for the spraying.

[Effect]

With the above configuration, by converting the powder material into a wire thermal spray material, handling becomes easier and work efficiency is improved, and
There is less risk of contamination with impurities, and the thermal spray material can be continuously fed to the thermal spray gun, allowing large quantities of thermal spraying to be carried out.Furthermore, it is possible to obtain a thermal spray coating with a mixture ratio tailored to the purpose, and to It is possible to obtain a thermal spraying method for a powder thermal spray material that allows a uniform thermal spray coating to be obtained without changing the mixing ratio during feeding.

〔Example〕

An embodiment of the thermal spraying method for the powder thermal spraying material of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the implementation procedure of the method of the present invention, and FIG. 2 is a cross-sectional view of the cored wire in the same.

In FIG. 1, a voltage is applied to the electrode 2 and nozzle 3 of the plasma spray gun 1 from a power source (not shown), and the plasma jet 4 is ejected from the nozzle 3 toward the surface of the material 9, and the cored wire 5 is transferred to the feeding roller. 6 into the plasma jet 4 of the nozzle 3 via a conduit cable 7.

As shown in FIG. 2, this cored wire 5 is formed into a long wire by enclosing a powder material 5b in a hoop 5a of an appropriate diameter. Further, by using an appropriate mixed powder as the powder material 5b, the thermal spray coating composition can be set to have an appropriate coefficient of thermal expansion.

The cored wire 5 melted by the plasma jet 4 becomes high-temperature, high-velocity flying molten particles 8, which collide and adhere closely to the surface of the material 9, forming a buffer coating 10 and a thermal spray coating 11 on the surface. At this time, by appropriately changing the composition of the component 1 of the cored wire 5 when forming the buffer coating 10 and that when forming the thermal spray coating 11, the buffer coating 1
The thermal expansion coefficient of 0 can be set to be intermediate between that of the material 9 and that of the thermal spray coating 11, and it can also be made to gradually change in a gradient manner.

Thus, according to such a thermal spraying method, the following effects can be achieved.

(1) By using the cored wire 5 in which the powder material 5b is enclosed in the hoop 5a, the thermal spray material is made into a wire rod, which makes handling easier and improves work efficiency, and the powder material 5b is covered with the hoop 5a. Therefore, there is less risk of contamination with impurities.

(2) The trouble G when feeding the cored wire 5 is small, the feeding to the plasma spray gun 1 can be carried out continuously at a uniform speed, and a large amount of heat can be sprayed.

(3) By changing the volume ratio of the hoop 5a and the powder material 5b, a thermal spray coating 10.11 can be obtained depending on the purpose. Further, when mixed powder is used in the hoop 5a, if it is mixed uniformly during filling, there will be no difference in the mixing ratio during feeding, and a uniform thermal spray coating of 10° 11 can be obtained.

〔Effect of the invention〕

In short, according to the present invention, when thermal spraying is performed on the surface of a material that has a coefficient of thermal expansion different from that of a powder thermal spray material, by thermal spraying using a cored wire with the powder material enclosed in a hoop, the powder material is transformed into a wire rod. By making it a thermal spray material, it is easier to handle, improving work efficiency, reducing the risk of contamination with impurities, and allowing the thermal spray material to be continuously fed to the thermal spray gun at a 4° angle, allowing for large-volume thermal spraying. Furthermore, the present invention provides a thermal spraying method for a powder thermal spray material that can obtain a thermal spray coating with a mixing ratio according to the purpose and a uniform thermal spray coating without changing the mixing ratio during feeding. It is extremely useful.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the thermal spraying method for the powder thermal spraying material of the present invention, and FIG. 2 is a cross-sectional view of the core wire in the same. FIG. 3 is a schematic diagram of a conventional thermal spraying method. DESCRIPTION OF SYMBOLS 1... Plasma spray gun, 2... Electrode, 3... Nozzle, 4... Plasma jet, 5... Cored wire, 5a... Hoop, 5b... Powder material, 6...
・Feeding roller, 7... Conduit cable, 8...
・Flying molten particles, 9...Material, 10...Buffer film,
11...Thermal spray coating. Agent: Masafumi Tsukamoto, Patent Attorney

Claims (1)

[Claims] A thermal spraying method for a powder thermal spray material, characterized in that the thermal spraying is carried out using a cored wire in which the powder material is enclosed in a hoop when the powder thermal spray material is sprayed onto the surface of a material that has a coefficient of thermal expansion different from that of the powder thermal spray material.