JPH0225558A - Thermal spraying method - Google Patents

Abstract

PURPOSE:To form a film having a low content of oxides and having low porosity on the surface of a base material while preventing the inclusion of oxygen and moisture when molten particles are sprayed by replacing the air in a vessel- shaped body to be sprayed by an inert gas. CONSTITUTION:An inert gas G is supplied into the internal space of the body 1 to be sprayed from a device for supplying an inert gas such as Ar and N2 through an injection pipe 15, a control valve 11, and an opening 13 to carry out thermal spraying. The air in the body 1 is simultaneously discharged to the outside through an opening 12, an exhaust valve 10, and an exhaust pipe 14. As a result, the air in the body 1 is replaced by the inert gas G, and the inside of the body 1 is filled with the inert gas G. The molten particles of metal, etc., are sprayed into such an atmosphere of the inert gas G from a thermal spraying gun 17 to cause electrical-molten-wire spraying, and a film having a low content of oxides and having extremely low porosity can be formed on the inner surface 22 of the body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal spraying method, which is a coating method in which particles of molten metal, ceramics, etc. are sprayed onto the surface of an object to be thermally sprayed to form a film.

[Prior art and problems to be solved by the invention] The coating formed by conventional thermal spraying has many pores that reach the surface of the object to be sprayed, and corrosive gases, solvents, etc. can enter through these pores and cause the coating to deteriorate. This has caused problems such as peeling and damage.

An object of the present invention is to provide a thermal spraying method capable of solving the above-mentioned problems and forming a coating having extremely low oxide content and porosity.

[Means to solve the problem]

In order to achieve the above object, in the thermal spraying method of the present invention, the container-shaped object to be thermally sprayed is sealed, the air inside the object to be thermally sprayed is exhausted, and the inert gas is injected into the container-shaped object to be thermally sprayed. The inner surface of the object to be thermally sprayed is sprayed in an inert gas atmosphere.

In addition, an inert gas is injected into the sealed chamber and the air inside the sealed chamber is expelled to maintain the inside of the sealed chamber at a predetermined pressure slightly exceeding atmospheric pressure, and the sealed chamber is sealed in an inert gas atmosphere inside the sealed chamber. It is used to thermally spray objects placed indoors.

[Effect]

By replacing the air inside the container-shaped object to be sprayed with inert gas, when spraying molten metal particles, the inert area is prevented from mixing with air, and oxygen, moisture, etc. are mixed into the molten particles. Moreover, since the thermal spraying work is performed inside the container-shaped object to be thermally sprayed, a sealed work chamber is not required.

Since the inside of the sealed chamber is maintained at a predetermined pressure slightly exceeding 1 atmosphere, the sealed chamber does not require special strength and does not need to have a special pressure-resistant structure.

When molten particles are sprayed, the molten particles are surrounded by an atmosphere of chemically inert gas, so no oxygen or moisture is mixed in, and the oxide content and porosity of the base metal surface are extremely low. A film is formed.

〔Example〕

Embodiments will be described with reference to the drawings. In FIGS. 1, 2, and 3, reference numeral 1 denotes a container-shaped object to be thermally sprayed, such as a pressure vessel, and the object to be thermally sprayed 1 has an open end. The shape is composed of a cylindrical portion 1a and a hollow conical portion 1b, and is placed on a flat plate 5 such as an iron plate placed horizontally! ! It is placed. A sealing member 6 made of hard rubber or the like having a substantially rectangular cross section is interposed between the flat plate 5 and the open end 2 of the object to be thermally sprayed 1, and the space between the opening @2 and the flat surface 5 is sealed. . Reference numeral 8 denotes an entrance/exit to the interior of the object to be thermally sprayed l, which is formed by opening a predetermined portion of the flat plate 5. Reference numeral 9 represents a sealing plate 9 which seals the entrance/exit 8 in an openable/closable manner. A passage 3 for communication between the outside and the inside of the object to be thermally sprayed l is formed below the flat plate 5, and the passage 3 communicates with an entrance/exit 8 and a communication opening 4 leading to the outside. Note that the communication port 4 is provided with a hinged door 7.

The conical part 1b of the object to be thermally sprayed 1 has an exhaust valve IO for discharging the air A from the object to be thermally sprayed 1, and the cylindrical part 1a has an exhaust valve IO for injecting inert gas G into the object to be thermally sprayed 1. An operating valve 11 is provided for operating, in particular the two pulps 10.11 are connected to the opening 12.1 of the object l to be sprayed.
Exhaust pipe 14 connected to and attached to 3. It is attached to the inert gas injection pipe 15.

The openings 12 and 13 are holes for attaching various parts, manholes, etc. of the object 1 to be thermally sprayed as a pressure vessel.

Reference numeral 16 denotes an automatic thermal spraying device, such as an arc melting wire method, which is disposed within the object to be thermally sprayed 1 and is movable on a plane Fi, 5. The thermal spraying device 16 includes a thermal spray gun 17, a compressor 18. An inert gas tank 19 for blowing inert gas such as argon or nitrogen is provided. The thermal spray gun 17 is movable horizontally along a lateral guide 20 and vertically along a vertical guide 21.

To perform thermal spraying, the injection pipe 15. Operation valve 11.
Inert gas G is supplied and injected into the internal space of the object to be sprayed l through the opening 13, and at the same time, the inert gas G is supplied and injected into the internal space of the object to be sprayed l through the opening 12. Exhaust valve 1
0. Internal air is exhausted to the outside via the exhaust pipe 14.

The air inside the object to be thermally sprayed L was replaced with inert gas G, and the pressure of inert gas G was raised to slightly above atmospheric pressure, that is, gauge pressure +0.1 kg (/cj ~0.
2 kg r / cd (7) I After holding the pronation setting and bringing it into a saturated state with inert gas G, such an inert gas G
By performing electric wire thermal spraying by spraying molten particles of metal or the like from a thermal spray gun 17 in an atmosphere of . Distance M between thermal spray gun 17 and inner surface 22
It is preferable to set W to 50-250.

As another example, as shown in FIG. 4, a sealed chamber 23 is formed by a box-shaped structure 25, and the inside of the sealed chamber 23 is made similar to the above example, and +0.1 kg f /
The surface of the object to be thermally sprayed 24 may be thermally sprayed by the thermal spraying device 16 in an atmosphere of inert gas G at a predetermined pressure within the range of cj to 0.2 kg r/cd (gauge pressure). In the example, a case is shown in which a cylindrical shaft, which is the object to be thermally sprayed, is supported by rollers 28, 28, and at the same time, the object to be thermally sprayed 24 is rotated and the surface thereof is thermally sprayed. Note that the exhaust valve IO is attached to the ceiling wall 26 of the structure 25, and the operation valve 11 is attached to the side wall 27. 29 is the area around the entrance and exit of the sealed structure.

Although not shown, it is preferable to use a thermal spray port bot instead of the automatic thermal spraying device 16.

Of course, it is also possible to carry out the work while holding the hand-held thermal spray gun 17.

Figures 5 to 8 show micrographs of thermal spray coatings formed by thermal spraying experiments under various conditions.
In the figure, C is the formed sprayed coating, S is the sprayed coating layer, and B is the surface layer of the base material that is the material to be sprayed.

FIG. 5 shows a thermally sprayed coating C formed on the surface of a base material when the spraying was carried out in the general atmosphere using compressed air, and the thermally sprayed coating C has a large number of pores.

In Figure 6 (1) to Figure 6 (V), this is the case where argon was used in the general atmosphere, and the unit area was larger than when blowing with compressed air (in the case of Figure 5). Although the number of pores per unit, that is, the distribution ratio, is quite small, there are pores with large pore diameters.

In addition, D in Table 0 when thermal spraying was carried out under the conditions as shown in Table 1.
indicates liquid argon, and E indicates gaseous argon from a high-pressure vessel.

Table 1 Thermal spray conditions however, By gas melt wire method.

In Fig. 7 (1) to Fig. 7 (IV), the conditions were the same as in Fig. 6 for the points where argon was used in the general atmosphere, but the difference was that the spraying distance was changed. However, in this case, as the spraying distance increases, the porosity also increases.

FIGS. 8(1) to 8(IV) show cases in which the method according to the embodiment of FIG. 1 or FIG. 4 is used. Of these, Fig. 8 (i) and Fig. 8 (■) use the electric welding method, Fig. 8 (!It) and Fig. 8 (IV) use the gas welding method, and argon is used for spraying. This shows the case using gas. In the case of the above-mentioned electric welding wire type, that is, in Fig. 8 (1), the pores are dug and minute;
In Figure (■), the distribution ratio of pores is extremely small, and only extremely fine pores exist near the surface of the base material.Furthermore, in Figures 8 (m) and 8 (IV), Only extremely fine pores exist, and the distribution rate is extremely small.

In the embodiment shown in FIG. 1, a pressure vessel is shown as the object to be thermally sprayed, but unlike this, it may be in the shape of a container, that is, a part of a structure such as a building having an opening.

In any of the above embodiments, the air is replaced with a saturated state of inert gas and the thermal spraying work is carried out in an atmosphere of inert gas G. Therefore, when molten particles such as metal are sprayed, there is a possibility that the inside of the molten particles may A film with extremely low oxide content and porosity is formed without the contamination of oxygen, moisture, etc. Since there is no need to reduce the thermal spraying distance, there is no need to overheat the base material.

In the embodiment shown in FIG. 1, since the object to be thermally sprayed 1 itself is used as a sealed chamber, a separate sealed chamber for holding the inert gas G is not required. In addition, the inert gas G is at low pressure (0,
1 to 0.2 kgr/cd (gauge pressure), the material to be sprayed 1 does not require strength. In the embodiment shown in FIG. Since the pressure is set at a low pressure of 0.1 to 0.2 kgf/cd (gauge pressure), the sealed chamber 23 does not require strength.

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

(2) It is possible to form a film with extremely low oxide content and porosity on the inner surface 22 or surface of the objects 1, 24 to be thermally sprayed. Therefore, it has anti-rust and anti-corrosion effects and improves chemical resistance.

■ No separate sealed chamber for holding inert gas G is required.

■ In order to seal the interior of the thermal spraying object 1 and the sealed chamber 23, there is no need to maintain the interiors at high pressure or high/low vacuum. The thermal spraying object 1 and the sealed chamber 23 may be simple ones and do not require mechanical strength, so the present invention can be easily applied even when the sealed chamber 23 is a large structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view showing one embodiment of the present invention, FIGS. 2 and 3 are enlarged partial sectional views, respectively, FIG. 4 is a sectional side view showing another embodiment, and FIGS. The figures are microscopic photographs of the sprayed coatings formed on the surface of the base material. l...Object to be thermally sprayed, 22...Inner surface, 23...Sealed chamber, 24...Object to be thermally sprayed, A...Air, G...Inert gas. Kanmeta Engineering Co., Ltd. Figure Reference A/'' Procedural amendment (trial) October 15, 1988 1, Hanyu's J ShiR 1988 1 No. 174799 2, Name of the invention Thermal spraying method 3,' 4. Person making the correction 4. Relationship with proxy case Patent applicant name: Kanmeta Engineering Co., Ltd. Cloud 5
30 Phone: (06) 344-0177 Chiyoda Building West Annex, 2-5-8 Umeda, Kita-ku, Osaka (all dates 1932)
(September 27, 2013) 6. Subject of amendment (1) Field for brief explanation of drawings in the specification. 7. Contents of amendment (1) "Figures 5 to 8\1, -n' in page 11 of the specification, paragraphs 181 to 2,

Claims (2)

[Claims] 1. The container-shaped object to be thermally sprayed 1 itself is sealed, the air A in the object to be thermally sprayed 1 is exhausted, and an inert gas G is injected into the container-shaped object to be thermally sprayed 1 in an atmosphere of inert gas G. A thermal spraying method characterized in that the inner surface 22 of the object l to be thermally sprayed is thermally sprayed. 2. Inert gas G is injected into the sealed chamber 23 and air A is removed from the sealed chamber 23 to maintain the sealed chamber 23 at a predetermined pressure slightly exceeding atmospheric pressure. A thermal spraying method characterized in that a thermal spraying target 24 placed in the sealed chamber 23 is thermally sprayed in an atmosphere of active gas G.