JPS58122077A - Melt spraying method of two layers - Google Patents

Abstract

PURPOSE:To obtain high adhesive strength by melt spraying an autogeneous metal on the surface of a base material and melting the same by heating then melt spraying a principal melt spraying material while maintaining the base material at specific temp. CONSTITUTION:First, an autogeneous metal of Ni-Cr-Si-B or Ni-Si-B is melt sprayed at 200-300 deg.C to form the 1st layer; thereafter, the melt sprayed layer is melted by heating to about 1,050 deg.C to join the same firmly to the base material. In succession, a material such as ZrO2, SiN4 or Al2O3 that forms the 2nd layer is melt sprayed on the 1st layer while said layer is held sufficiently softened by maintaining the base material at temp. just below the m.p. of the autogeneous metal forming the 1st layer, for example, 900-1,000 deg.C without cooling the surface to be melt sprayed, whereby the application is completed. Thus, the base material 1 and the film 2 of the autogeneous metal in the 1st layer are bound firmly, and the boundaries between the film 2 and the film 3 of the 2nd layer assume intricate rugged shapes; therefore, entanglement of both layers at the boundaries is large and the activation of the film 2 is accelerated by heating at high temp., whereby high adhesive strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a thermal spraying method used as a method for treating the surface of metals.

The biggest technical problem in current thermal spraying is the thermal spray layer (
The adhesion (also called thermal spray coating), that is, the peel strength, is 2 to 2.
It is as low as 3 kg/1.

This tendency is particularly noticeable in thermal spraying of non-metals such as ceramics. therefore.

When spraying onto areas subject to repeated thermal stress or vibration,
The film is easy to peel off, so its practical application has been delayed.

In view of the current situation, the present invention primarily provides a thermal spraying method for increasing the peel strength between a base material and a thermally sprayed coating.

Hereinafter, the present invention will be explained in detail according to examples.

FIG. 1 shows that Ni-Cr-Si is formed in the ~th layer according to the present invention.
This figure shows the temporal change in the surface temperature of the base metal during thermal spraying of a B-based self-fusing metal using ZrOs as the second layer. This is what is shown.

In Figure 1, Category 1 indicates the temperature change of the base material when the self-fusing metal forming the first layer is sprayed, Category ■ indicates the temperature change during the melting treatment of the self-fusing metal, and Category ■ indicates the temperature change of the base material when the self-fusing metal forming the first layer is thermally sprayed. The temperature change of the material forming the two layers during thermal spraying, and the category ■ indicate the temperature change of the base material after thermal spraying is completed.

That is, the main point of the present invention is to first form a first layer by thermally spraying a self-fusing metal such as Ni-Cr-Si-B or Ni-Si-B at 200 to 300°C (Category I). By heating and melting the layer at a temperature of, for example, about 1050° C., the bond to the base material is strengthened (category 1). Without subsequently cooling the surface to be thermally sprayed, a temperature of 900 to
Maintain the temperature at 1000°C and form the second layer where the first layer has sufficiently softened Zr0t, 5isN.
4+ The process is to complete the thermal spraying process by spraying a material such as Altos.

In other words, before spraying the desired thermal spray material.

First, relatively low melting point Ni-Cr-8i-B and Cr-
A self-fusing metal such as 8i-B system is sprayed onto the surface of the base material, and it is heated and melted while maintaining the surface of the base material just below the melting temperature to achieve the desired Zr0t, 5isN+,
This method involves spraying a thermal spray material such as AbOs onto the surface of the self-fusing metal.

As is clear from the schematic diagram of FIG. 2, the effect of the present invention is that the base material 1 and the first self-fusing metal coating 2 are more firmly bonded by melting and diffusion.

The boundary between the first layer, the self-fusing metal coating 2, and the second layer, the thermal spray coating 3, has complex irregularities because the spray particles forming the second layer collide with each other while the first layer is sufficiently softened. Because of this, the entanglement of both layers at the boundary is large, and the activation of the self-fusing metal film 2 of the first layer is promoted by high-temperature heating.
Both layers are bonded more firmly and high peel strength can be obtained.

In thermal spraying construction according to the present invention, construction of Class 9 1 and after is as follows:
In order to prevent high-temperature oxidation, the process is usually carried out in an inert gas atmosphere, but since the self-fusing metal film 2 that forms the first layer contains a large amount of deoxidizing agent, it has high oxidation resistance. Construction can also be carried out in the atmosphere.

Further, division I-1 in FIG. 1 can be performed continuously, or each can be performed independently.

The present invention exhibits great effects in thermal spraying of non-metallic materials such as ceramics. That is, in FIG. 2, when the second layer of thermal spray coating 3 is made of ceramic, the bond is strengthened by the compressive stress due to the difference in the coefficient of thermal expansion between the two shoulders, in addition to the above-mentioned two effects.

In other words, since the self-fusing metal coating 2 in the first layer has a larger coefficient of thermal expansion than the ceramic in the second layer thermal spray coating 3, the thermal expansion coefficient of the first layer self-fusing metal coating 2 is larger than that of the ceramic grains that have entered the recesses during the cooling process in Section 2 of Figure 1. Compressive stress is applied to the boundary to strengthen the bond between the two layers. In addition, in order to reliably generate the complex unevenness at the boundary between both layers as shown in Fig. 2, it is necessary to It is desirable to use coarse powder particles of 70 to 150 mesh, and to use fine powder particles of 150 to 200 mesh for the surface layer of the second layer thermal spray coating 3 in order to improve the quality of the coating 3.

As described above, in the thermal spraying method of the present invention, a thermal spray coating 2 of a self-fusing metal with good wettability to the base material 1 is provided as an intermediate layer, and after sufficient bonding with the base material 1 is performed, Following the heating and melting treatment, thermal spraying is performed using the original thermal spraying material while maintaining the temperature at at least 900 to 1000°C, and due to the above-mentioned effects, a high peeling rate of 6 to 7 g/-, which cannot be obtained with conventional methods, is achieved. It provides strength (adhesion).

This method is extremely useful for industry as it improves the quality and durability of thermal sprayed coatings by overcoming the drawbacks of conventional methods.

The thermal spraying method of the present invention can be applied to general thermal spraying of structures and parts that require heat resistance, wear resistance, and corrosion resistance, but it is especially applicable to ceramic thermal spraying for the purpose of heat-insulating coating. can be increased.

[Brief explanation of the drawing]

FIG. 1 shows the temporal change in base material surface temperature in the thermal spraying method of the present invention, and FIG. 2 schematically shows an enlarged cross section of the thermal sprayed coating of the present invention. 1... Base material, 2... Self-fusing metal coating, 3... Original thermal spray coating. 1, A, 2 Procedural amendments (voluntary) June 9, 1980 Commissioner of the Japan Patent Office Mr. Haruki Shimada 1 Indication of the case 1982 Patent Application No. 3196 2 Name of the invention Double-layer thermal spraying method 3, Relationship with the case of the person making the amendment Patent applicant address 2-5il1 Marunouchi, Chiyoda-ku, Tokyo
Part name (620) Mitsubishi Heavy Industries, Ltd.
” is corrected. (2) Correct "cr-3i-B series" in line 11 of page 3 to "rNi-St -B series." (3) On page 4, lines 6 to 4, "due to the collision of thermal spray particles" is corrected to "due to the collision of thermal spray particles." (4) In the 4th line of page 5, change “by compressive stress” to “
Corrected to ``by the generation of compressive stress.''That's all (Sir)

Claims (1)

[Claims] A thermal spraying method used for surface treatment of objects. A two-layer thermal spraying method characterized by spraying a self-fusing metal onto the surface of a base material, heating and melting it, and then spraying another object while maintaining the temperature just below the melting point of the metal.