JPH0512033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a low-pressure thermal spraying method, and particularly to a low-pressure thermal spraying method capable of forming a thermally sprayed layer of excellent quality.

(Prior art) In recent years, a thermal spraying method (LPC thermal spraying) has been developed in which the object to be treated is placed in a chamber, the chamber is maintained in an inert gas atmosphere close to a vacuum of about 20 to 50 Torr, and plasma spraying is performed in this state. law) is attracting attention. The reason is that in this method,
Since thermal spraying is carried out under a low-pressure atmosphere, the thermal spray particles traveling from the gun to the workpiece can be prevented from being cooled or oxidized by atmospheric gas during their movement, and their speed can be reduced. This is because it is possible to prevent a decrease in the thermal spray coating, and as a result, the performance of the thermal spray coating can be improved. This method also has the advantage of preventing the generation of noise.

(Problem to be Solved by the Invention) By the way, it is necessary to perform blasting on the object to be treated before thermal spraying, but in the conventional method described above, blasting is not performed in the atmosphere before thermal spraying. It is common practice to carry the treated object into a chamber, create a low-pressure atmosphere in the chamber, and perform plasma spraying. Therefore, in the conventional method, the clean surface of the object to be treated, which has been subjected to blasting, is exposed to the atmosphere again until it is thermally sprayed, and is oxidized or has oxygen attached to it.
As a result, even if thermal spraying is performed in a low-pressure atmosphere, the surface of the object to be treated is oxidized or has oxygen attached to it as described above, so there is sufficient space between the thermal spray layer and the object to be treated. A problem has arisen in that good adhesion cannot be obtained. This is a problem when the material to be processed is steel or aluminum, but it is especially true for turbine blades (base material MM007,
This is a big problem when high temperature peel strength is required for the thermally sprayed layer, such as the thermally sprayed layer Nikolali (trade name).

The present invention has been made in view of the above, and its object is to provide a low-pressure thermal spraying method that can form a thermal sprayed layer with improved quality, particularly improved adhesion to the base material.

(Means for Solving the Problems) The low-pressure thermal spraying method of the present invention, which meets the above objectives, involves blasting a workpiece placed in a depressurized chamber using an inert gas, and then blowing the workpiece into the atmosphere. The process is characterized in that the thermal spraying is carried out on the object to be treated under a reduced pressure atmosphere without exposing it to the atmosphere.

(Function) According to the above method, an oxide film is not formed on the surface of the object to be treated before low-pressure thermal spraying, and oxygen does not adhere to the surface of the object, unlike conventional methods, and it is possible to form a thermal spray layer on a clean surface. , it becomes possible to improve the quality of the sprayed layer, especially the peel strength.

(Example) Next, specific examples of the low-pressure thermal spraying method of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a vacuum chamber, and reference numeral 2 indicates an evacuation device, which allows the inside of the vacuum chamber 1 to be evacuated to a predetermined degree of vacuum. A workpiece A is disposed in the vacuum chamber 1, and the workpiece A is driven within the chamber 1 in a necessary direction by a drive source (not shown), for example, in the case shown in the figure. is designed to be able to be driven vertically and rotationally. Also, on one side wall of the chamber 1, a plasma spray gun 3 is installed horizontally.
This thermal spray gun 3 is used to spray the workpiece A. Note that the plasma spray gun 3 is connected to a power source and a powder supply source 4. Further, a blast gun 5 is attached to the side wall of the chamber 1 at a position below the thermal spray gun 3.
A blasting material supply source 6 is connected to. In this case, various blasting materials can be used, and specific examples include steel balls, steel chips, glass beads, ceramic blasting materials, and the like. Further, an inert gas supply source 7 such as argon is connected to the thermal spray gun 3 and the blast gun 5, respectively, and the inert gas can be switched and supplied to the thermal spray gun 3 and the blast gun 5 as necessary. It's been like that.

Next, the processing procedure for the object A to be processed in the above-described low-pressure thermal spraying apparatus will be explained. First, the object to be processed A
is inserted into the chamber 1, and the pressure inside the chamber 1 is reduced to a predetermined degree of vacuum. Next, the blast gun 5 is activated and the object A to be processed is driven, thereby performing blasting on the surface of the object A. When this blasting process is completed, the thermal spray gun 3 is then activated and the object A is driven to form a thermal spray layer on the surface of the object A. When this thermal spraying process is completed, the interior of the chamber 1 is The pressure is returned to atmospheric pressure, the object to be processed A is taken out from the chamber 1, and a series of treatments is completed.

In the above, the object to be treated A is blasted in a low-pressure chamber 1 in an inert atmosphere that does not contain harmful gases such as oxygen, and then continuously subjected to low-pressure thermal spraying without exposing its surface to the atmosphere. It becomes possible to do this. Therefore, it is possible to form a sprayed layer on a clean surface rather than on the contaminated surface of object A as in the past, and as a result, the quality of the sprayed layer, especially the adhesion between the base material and the sprayed coating, is improved. It becomes possible to improve.

FIG. 2 shows a modified example of the low-pressure thermal spraying device, and this is an example of a device in which the blast gun 5 and the thermal spray gun 3 are integrally formed, that is, a thermal spray gun 8 having a blasting function is used. . In this case, the other parts have substantially the same structure as above, and the same parts are indicated by the same reference numerals.

This apparatus can also perform a series of treatments similar to those of the above apparatus, and can form a thermally sprayed coating of excellent quality.

Although the embodiments of the low-pressure thermal spraying method of the present invention have been described above, the low-pressure thermal spraying method of the present invention is not limited to the above embodiments, and can be implemented with various modifications. For example, although the above example uses plasma spraying, other spraying methods such as gas spraying may be used.

(Effects of the Invention) The low-pressure thermal spraying method of the present invention is configured as described above. Therefore, according to the low-pressure thermal spraying method of the present invention, the quality, especially the adhesion to the base material, is improved and the It becomes possible to form a sprayed coating with a high peel strength.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of a low-pressure thermal spraying apparatus used to carry out the method of the present invention, and FIG. 2 is an explanatory diagram of a modified example thereof. 1...Chamber, 3, 8...Thermal spray gun, 5...
...Blast gun, A...Object to be processed.

Claims (1)

[Claims] 1 After performing blasting using an inert gas on the object to be treated placed in a reduced pressure chamber,
A low-pressure thermal spraying method characterized in that thermal spraying is performed on the object to be treated in a reduced pressure atmosphere without exposing it to the atmosphere.