JPH03210455A - Method for testing adhesion strength of flame sprayed film - Google Patents

Abstract

PURPOSE:To accurately measure adhesion strength by fixing the surface of the flame sprayed film of a test piece and the flat surface of a jig in a pressure contact state after cleaning the flame sprayed film formed to the flat surface of the test piece and the flat surface of the jig in contact with the film and applying tensile force or shearing force to the test piece and the jig. CONSTITUTION:After, the flatened surface of a flame sprayed film 3 and the flat surface of a jig 2 are polished electrochemically, sputtering is applied to the surface of the flame sprayed film 3 of a test piece 1 and the flat surface of the jig 2 to shave off the surfaces of both of them and the impurities in the vicinity thereof. Next, the flame sprayed film 3 of the test piece 1 and the flat surface of the jig 2 are mutually abutted and pressed for a predetermined time to be bonded by interatomic attraction. Subsequently, tensile force is allowed to act on the test piece 1 and the jig 2 so as to relatively move both of them and shearing force is further allowed to act on both of them in the direction parallel to the surface of the flame sprayed surface of the test piece 1 to measure the max. adhesion strength of the flame sprayed film 3 immediately before the film 3 is released.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for testing the adhesion strength of a thermally sprayed coating of metal, ceramics, cermet, etc. to a base material, which is thermally sprayed onto the surface of the base material in order to protect the surface of the base material. Regarding.

[Prior Art] The thermal spraying method, in which metals, ceramics, etc. in a molten state is continuously sprayed onto the surface of a base material and is laminated on the surface to form a coating, has a wide selection range of base materials and coating materials.
It has been widely adopted as an effective method for protecting the surface of base materials.

In particular, in recent years, advances in thermal spraying technology have improved the adhesion strength, which is a drawback of thermal spray coatings, and it has become possible to form thermal spray coatings with excellent properties, so the applications of thermal spraying have tended to further expand. Correctly evaluating the adhesion strength of thermal spray coatings has therefore become an important issue.

The adhesion strength of various types of coatings, not just thermal spray coatings, can be determined mainly by tensile adhesion strength tests, which measure the strength against forces perpendicular to the bonding interface between the base material surface and the coating, and by shear adhesion strength tests, which also measure the strength against forces along the bonding interface. It will be evaluated by the test.

Figure 4 shows the tensile adhesion strength test method specified in JIS H8666, in which a test piece 11 and a jig 12 are prepared, each of which has a flat surface of the same shape and size, and a test piece 1 is prepared.
After forming the thermal spray waves 11j13 on the flat surface of the test piece 11, the flat surfaces of the jig 12 are bonded to the thermal spray coating 13 using the adhesive 14 without shifting the positions of the test piece 11.
．． A method of connecting the jig 12 to chucks 17 and 18 of a tensile testing machine using universal joints 15 and 16, respectively, and applying a vertical force to the sprayed coating 13 to measure the adhesion strength of the sprayed coating to the base material. It is.

Figure 5 is “Journal of High Temperature Society Vol. 1.3. pp. 153-160 1
989 J, in which a thermal spray coating 23 is formed on the flat surface of a test piece 21, and the flat surface of a jig 22 is attached to this thermal spray coating 23 using an adhesive 24. After forming a groove 23a between the jig 22 and the surrounding thermal spray coating 23 that is not directly bonded and separating the test piece 2,
1 and the jig 22 are similarly connected to a chuck of a tensile tester (not shown) via joints 25 and 26, and the adhesion strength is measured.

[Problems to be Solved by the Invention] By the way, in the conventional method as described above, in order to apply a tensile force in the vertical direction to the thermal sprayed coating 1323, the thermal sprayed coating 13.2
A jig 12° 22 is fixed to the surface of 3 using an adhesive 14, 24. However, if the adhesion strength of the film is lower than the adhesive strength, no problem will occur, but if the adhesion strength is greater than the adhesive strength, measurement will not be possible, or in a high temperature atmosphere where adhesive cannot be used, or if the adhesive is There was also a problem in that it was impossible to measure in liquids that would dissolve it.

For example, epoxy resin type adhesive is 150'C~300''
C loses its adhesive strength, and epoxy resin adhesives cannot be used in such solutions because they are dissolved in organic solvents such as nitropenzole. Furthermore, since the thickness of the thermally sprayed coating is approximately a few inches at most, means such as welding that exert a thermal or mechanical influence cannot be used.

The present invention was made in view of the above circumstances, and its purpose is to provide a thermal sprayed coating that has an adhesion strength exceeding that of an adhesive, or a thermal sprayed coating that allows adhesion strength measurement in environments where it is difficult to use adhesives. The present invention provides a method for testing the adhesion strength of a film.

[Means to solve the problem]

The adhesion strength test method for thermal sprayed coatings according to the present invention involves fixing the flat surface of a jig to the thermal sprayed coating surface formed on the flat surface of a test piece,
A thermal sprayed coating formed on a flat surface of the test piece in a method for testing the adhesion strength of a thermal sprayed coating in which a tensile force or a shearing force in a direction perpendicular to the thermal sprayed coating is applied to the thermal sprayed coating by relative movement between the test piece and a jig. After cleaning the surface by sputtering the flat surface of the jig to be joined to this, the sprayed coating surface of the test piece and the flat surface of the jig are fixed by pressure, and the test piece and the jig are pulled together. It is characterized by applying force or shearing force.

(Function) According to the present invention, it is not necessary to use an adhesive and measurement can be performed without being influenced by the characteristics of the adhesive.

〔Example〕

The present invention will be specifically explained below based on the drawings.

FIG. 1 is a schematic diagram showing the main steps of the method for testing the adhesion strength of thermally sprayed coatings according to the present invention, and FIG. 2 is a flowchart thereof.

First, a test piece 1 and a jig 2 having flat surfaces of the same shape and size are prepared, and a thermal spray nozzle 5 is opposed to the flat surface of the test piece 1 as shown in FIG. 1(a) to form a thermal spray coating 3. (Step St). It is desirable that the flat surfaces of the test piece 1 and the jig 2 be made to have the same shape and two equal sizes in order to avoid stress concentration, improve measurement accuracy, and facilitate measurement work, but this is not the only option. For example, if the flat surface area of test piece 1 is
If the width is wider than that, a groove may be formed between the flat surface of the jig 2 and the surrounding thermally sprayed coating 3 not in contact with each other, as shown in FIG. 5, and the groove may be cut.

Next, step S is to flatten the sprayed coating 3 by mechanical polishing.
2), and after electrochemically polishing the surface of the flattened sprayed coating 3 and the flat surface of the jig 2 (step S3),
The test piece 1 and the jig 2 are set in a chamber (not shown), and in this state, as shown in FIG. The surfaces are irradiated with an ion beam or a neutral high-velocity particle beam, and impurities on and near both surfaces, such as several atomic layers (thickness 0.1 μm) of oxide, are scraped off by the sputtering action (step S4).

The inside of the chamber may be in an atmosphere as long as it does not generate any products that may interfere with the bonding of the flat surfaces of the thermally sprayed coating 3 of the test piece 1 and the jig 2 during bonding, which will be described later. For example, an atmosphere mixed with an inert gas such as Ar may be used, or a vacuum atmosphere may be used. Even in an atmosphere containing an inert gas such as Ar, the inert gas such as Ar does not remain as an impurity on the bonding surface and does not interfere with bonding. Moreover, even in a vacuum atmosphere, no undesirable products are produced, and there is no problem in bonding.

In the case of a vacuum atmosphere, it is preferable to use a high vacuum of about 10-''Pa.

Next, as shown in FIG. 1(C), the flat surfaces of the thermal spray coating 3 of the test piece 1 and the jig 2 are brought into contact with each other, and a pressure of about 100 MPa is applied for a predetermined period of time to bond them together by atomic attraction. (Step S5), then in the chamber as it is,
Or put it out in the atmosphere and apply a tensile force to move the test piece 1 and the anti-oxidant 2 relative to each other using a tensile tester, and also apply a shearing force in a direction parallel to the surface of the thermal spray coating 3 of the test piece 1, The maximum adhesion strength immediately before the sprayed coating peels off is measured (step S6).

Note that the material of the jig 2 is not particularly limited, but if the same material as the material of the thermal spray coating 3 is used, for example, if the thermal spray material is ceramic, the same ceramic or sintered material may be used.
The adhesion with the sprayed coating 3 is increased, and the influence of thermal stress that acts between the sprayed coating 3 and the flat surface of the jig 2 due to the difference in expansion coefficient due to temperature rise during the test can be avoided, further improving measurement accuracy. There are effects that can be enhanced.

[Test Example] Next, a comparative test between the method of the present invention and a method that does not belong to the method of the present invention will be specifically explained.

First, Example 1 of the present invention is - Rolling for shell structure! iii! (JIS
5S41) with a flat surface of 25 mm in diameter, and a jig made of the same < After that, it was degreased and pre-treated by sandblasting, and N1-A/! After performing base thermal spraying of the system to form a thermal spray coating with a thickness of 0.1 to 0.2 ff1m, a plasma spraying method is further applied on top of the thermal spray coating. 2
0. was deposited to a thickness of 500 μm.

The conditions for this plasma spraying are the thermal spraying material ^i! 20° powder supply rate: 90g/min, powder carrier gas (A
r) Flow rate: 371/min, plasma voltage near 0V, flow:
It is 500A.

Next, the surface of the sprayed coating formed on the test piece is mechanically polished, and the surface of the sprayed coating of this test piece and the flat surface of the jig are electrochemically polished, and then these are placed in a chamber.
'Pa, neutral Ar with beam energy 1°5 and ν.
The sprayed coating surface and the flat surface of the jig are simultaneously sputtered for about 20 minutes using a particle beam to clean the surface. As a result, the atoms on the surface of the sprayed coating and the flat surface of the jig become activated, that is, become highly reactive, so immediately compare the surface of the sprayed coating on the test piece with the flat surface of the jig at room temperature. , about 20 kgf/m'' for about 20 minutes to bond them together by atomic attraction.

In addition, in Example 2 of the present invention, Mg (1 is 0.1%
This is a case where the added Al2zoa ceramics were used and the other conditions were the same as in Example 1 of the present invention.

Further, in the conventional example, 5S41 was used as the material for the test piece and the jig, and epoxy Araldite^Tl was used as the adhesive for fixing the sprayed coating and the flat surface of the jig.

Examples 1 and 2 of the present invention and the conventional example were applied to a tensile tester at a temperature ranging from 300 to 800, and a tensile load was applied, and the maximum tensile load when the sprayed coating peeled off was calculated as the area of the sprayed coating. The value divided by is taken as the adhesion strength. The results are shown in Figure 3.

In Figure 3, the horizontal axis shows temperature (k), and the vertical axis shows close contact! (M
Pa) is shown. In the graph, the ○ mark indicates the result of the conventional example, the open mark indicates the result of the present invention example 1, and the ◇ mark indicates the result of the present invention example 2.

As is clear from this graph, in the conventional example, the adhesive melted at about 500, making it impossible to measure, but in Inventive Example 1, it was possible to measure up to about 700, and in Inventive Example 2, it could be measured up to about 800. I understand that it is possible. In Example 1 of the present invention, separation occurred between the thermal sprayed coating and the jig almost simultaneously with the peeling of the thermal sprayed coating.

[Effect] As described above, in the method of the present invention, after cleaning the surface of the sprayed coating formed on the flat surface of the test piece and the flat surface of the jig by sputtering, the test piece and the jig are placed under vacuum. The present invention has excellent effects, such as making it possible to accurately measure adhesion strength even in a high-temperature atmosphere or in a liquid, since the test is performed by bonding by atomic attraction and applying tensile force and shear stress.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the main steps of the method of the present invention, FIG. 2 is a flowchart showing the main steps of the method of the present invention, FIG. 3 is a graph showing the test results of the method of the present invention and the conventional method, and FIG. Figure 5 is a schematic diagram showing the conventional method. 1...Test piece 2...Jig 3...Thermal spray coating cylinder diagram 00 400 500 600 700 800 Temperature (Ko) Figure Figure Figure

Claims (1)

[Claims] 1. The flat surface of a jig is fixed to the sprayed coating surface formed on the flat surface of the test piece, and the relative movement between the test piece and the jig causes the sprayed coating to be coated in a direction perpendicular to this. In the adhesion strength test method for thermal sprayed coatings that applies tensile force or shearing force, the thermal sprayed coating formed on the flat surface of the test piece and the flat surface of the jig to be joined to it are sputtered to clean the surface. Thereafter, the sprayed coating surface of the test piece and the flat surface of a jig are fixed under pressure, and a tensile force or shear force is applied to the test piece and the jig.