JPS6247470A - Formation of thermally sprayed coating on inside surface of cylinder - Google Patents

Abstract

PURPOSE:To efficiently cool a cylindrical body and to obtain a thermally sprayed film which is dense and has good adhesiveness without contg. unwelded particles intruded therein by disposing a nozzle for spraying a cooling gas together with a thermal spraying gun into the cylinder and cooling the cylinder from the inside surface thereof. CONSTITUTION:The spraying gun 2 is directed in such a manner that the thermal spraying direction is perpendicular toward the inside surface of the cylindrical body 1. The distance between the inside surface of the cylinder and the gun 2 is specified to a prescribed length. The cooling nozzles 3, 4 are attached in 90 deg. and 180 deg. directions with respect to the spraying direction. The distance between the inside surface of the cylinder and the nozzles is specified to a prescribed length. Air or inert gas such as He, Ar or N2 is blown from the nozzles 3, 4 to cool the cylinder from the inside surface and to below off the unwelded particles, thereby preventing the intrusion of unwelded particles into the thermally sprayed coating layer. The cylindrical body 1 is moved back and forth while said body is kept rotated by a rotating body 5. The thermally sprayed coating layer having the excellent high-temp. durability and adhesiveness is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for thermally spraying an alloy or ceramic on the inner surface of a cylinder.

[Technical background of the invention and its problems]

Generally, when coating alloys or ceramics by thermal spraying, spraying is carried out while cooling the material by blowing air or inert gas onto it in order to prevent changes in the structure of the material and thermal distortion rings.

Recently, there has been a demand for thermal spray coating of alloys or ceramics on the inner surfaces of cylindrical bodies such as pipes for chemical plants, combustion tubes for gas turbines, and combustion tubes for jet engines.

In particular, since combustion tubes for gas turbines and combustion tubes for jet engines are used at extremely high temperatures, a good thermal spray coating layer with excellent high-temperature durability is required.

The conventional method for spray coating the inner surface of such a cylindrical body is to spray air or an inert gas onto the outer surface of the cylindrical body to cool it while spraying the inner surface of the cylindrical body. However, since this cooling method involves cooling from the outer surface, the cooling efficiency is poor and the cylindrical body cannot be cooled sufficiently. Furthermore, due to the cooling structure from the outer surface of the cylinder, unwelded particles exist inside the cylinder and get caught up in the thermal spray coating layer, making it impossible to obtain a good thermal spray coating layer. The present invention is a thermal spray coating method for the inner surface of a cylinder that overcomes these drawbacks.

[Object of the present invention]

The present invention provides a thermal spray coating method for the inner surface of a cylinder that overcomes the drawbacks of the prior art, and has a structure in which the thermal spray coating layer is directly cooled on the inner surface of the cylinder, so that the cylinder can be sufficiently cooled. I can do it. In addition, since the unwelded particles are blown away and removed, it is an object of the present invention to provide a thermal spray coating method for the inner surface of a cylinder, which forms a dense thermal spray coating layer with good adhesion without entrainment of unwelded particles.

[Summary of the invention]

The present invention relates to a thermal spray coating method for the inner surface of a cylinder, and in this method, a thermal spray gaff and a cooling nozzle are arranged on the inner surface of the cylinder, and air or inert gas is supplied from the nozzle. This is a thermal spray coating method for the inner surface of a cylinder, in which thermal spraying is performed while cooling.

In other words, this method has a structure in which air or inert gas is sprayed directly onto the thermally sprayed coating layer on the inner surface of the cylinder to cool it.
The cylindrical body can be efficiently and sufficiently cooled.

In addition, by blowing air or inert gas, unwelded particles can be blown off and removed, forming a thermally sprayed coating layer on the inner surface of the cylinder that is dense and highly active without entrainment of unwelded particles. It's a method. The cooling nozzle at this time is preferably installed at an angle of 45 degrees to 315 degrees with respect to the thermal spraying direction. This is because if the angle is 45 degrees or 315 degrees, it will adversely affect the spray flame and make it difficult to obtain a uniform spray coating layer. Further, in order to cool efficiently, it is preferable to use a plurality of cooling nozzles.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention using a cylindrical inner surface spraying machine will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of an apparatus used in the thermal spray coating method for the inner surface of a cylinder according to the present invention. The spraying gaff 2 is directed so that the spraying direction is perpendicular to the inner surface of the cylindrical body 1, and the distance between the inner surface of the cylinder and the spraying gun is set from 6 layers mts to 150 mts.

The cooling nozzles 3 and 4 are oriented at 90 degrees with respect to the thermal spraying direction.
Angled in the 80 degree direction, the distance between the inner surface of the cylinder and the nozzle is 1
From 0mm to 50 dragons. Air, helium gas, argon gas, nitrogen gas, or other inert gas is blown from this cooling nozzle to cool the inner surface of the cylinder. In addition, unwelded particles are blown away to prevent unwelded particles from becoming entangled in the thermally sprayed coating layer. The cylindrical body 1 moves back and forth while being rotated by the rotating body 5.

EXAMPLES The present invention will be described in detail below with reference to Examples.

[Embodiments of the invention]

Aim the spray gun so that the spray direction is perpendicular to the inner surface of a stainless steel (JIS standard 5 US304) cylinder with an inner diameter of 400 mm, a length of 1000 mm, and a thickness of 1.2 mm, and adjust the distance between the inner surface of the cylinder and the spray gun. I set it to 951. The cooling nozzle was installed in the 90v direction and the 180 degree direction with respect to the thermal spraying direction, so that the distance between the inner surface of the cylinder and the nozzle was 15 mm. Air was blown onto the inner surface of the cylinder from this cooling nozzle at a pressure of 4 kg/myg2 for cooling.

Thermal spraying is done using the plasma spraying method, with a plasma voltage of 36v1.
Ni-240o-16 with plasma current of 80OA
0r-13AAi-0,6Y alloy was thermally sprayed on the inner surface of the cylinder to a thickness of 0.1 mm, and then Zr02-5y2o was coated with Q, 2
Thermal spray coating was carried out to a thickness of mm. The cylinder has a speed of 420 per second
It spun back and forth at a speed of 2 mph per second while rotating at a speed of 1 mil.

When the inner surface of the cylinder was thermally sprayed under these conditions, the temperature of the cylinder reached a maximum of 75°C, indicating that it had been sufficiently cooled. Plate form impact test piece and width 25 silk, length 1
A 20 mm bending test piece was prepared and tested. Thermal shock tests were repeated 150 times in a furnace heated to 1000°C and then at room temperature. No cracks or peeling were observed in the thermally sprayed coating layer, indicating that it has excellent high-temperature durability. Ta. The bending test was conducted for 20 hours. As a result, fine cracks were observed on the curved surface, but there was no <1iIt and the adhesion was excellent.

〔Effect of the invention〕

As detailed above, the first layer of FC thermal sprayed coating produced by the thermal spray coating method for the inner surface of a cylinder according to the present invention has excellent high-temperature durability and adhesion. It is effective for

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an embodiment of the thermal spray coating method for the inner surface of a cylinder according to the present invention. 1...Cylindrical body 2...Thermal spray gun 3...Cooling nozzle 4...Cooling nozzle 5...Rotating body Representative Patent attorney Yudo Noriyoshi Chika Kikuo Takehana Figure 1

Claims (2)

[Claims] (1) A method for forming a thermal spray coating on the inner surface of a cylinder, characterized in that a thermal spray gun is disposed within the cylinder, and a cooling gas spraying nozzle is disposed within the cylinder to cool the cylinder from the inner surface. Method of forming thermal spray coating on inner surface. (2) The method for forming a thermal spray coating on the inner surface of a cylinder according to claim 1, wherein the cooling gas is sprayed at a position different from the thermal spraying position.