JPH0128828B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a composite thermal spray material made of metal and ceramic. Ceramics such as metal oxides, metal carbides, metal nitrides, metal silicides, and metal borides are generally high melting point materials with high hardness, and are substances with excellent heat resistance, corrosion resistance, oxidation resistance, and wear resistance. known as. A method of coating the surface or a portion of a material with the above-mentioned ceramic using thermal spraying technology to significantly improve the material quality of the material is becoming popular. When spraying ceramic onto a metal base, it is difficult to obtain a strong coating because the ceramic is a different material from the base and has weak adhesion. In order to give strong adhesion to the sprayed coating, it is necessary to roughen the base surface, spray a material with excellent adhesion on the base,
Alternatively, attempts have been made to use a metal that is easily alloyed with the base material as a binder. Methods of using metal as a binder include plating the surface of ceramic particles with metal, or coating with metal using physical vapor deposition, electrophoresis, slurry method, etc. Furthermore, methods have been proposed in which composite particles are obtained by sintering a mixture of ceramic powder and metal powder, or by using a binder. However, ceramics that have undergone wet processing tend to change in quality and lose their original properties, and the metal coating has weak adhesion and falls off during the thermal spraying process, making it unable to fulfill its role as a binder. Further, when dry processing such as physical vapor deposition is used, it is difficult to coat a sufficient amount of metal. Even when sintering a molded mixture of ceramic powder and metal powder, it is difficult to obtain tightly sintered fine powder particles suitable for thermal spraying. In addition, composite powder using a binder has C.
Significant drawbacks include the mixing of elements harmful to raw metals such as PS, which limits the range of use, and the inability to obtain a homogeneous and strong sprayed coating because the ceramic particles and metal separate during thermal spraying. There is. The present invention aims to eliminate these drawbacks and to obtain a homogeneous and strong thermal sprayed coating.The present invention aims to solve these drawbacks and to obtain a homogeneous and strong thermal sprayed coating. It provides thermal spray materials. The composite thermal spray material produced by the method of the present invention is characterized in that metal is mechanically interlocked with the surfaces of individual ceramic particles to form an integral bond, thereby exhibiting a so-called mechanical alloy-like structure. When the thermal spraying material of the present invention is used, there is little contamination of impurities other than the target metal, and the ceramic and metal maintain a strong integral bond even during thermal spraying, so the thermal spraying material has the excellent properties unique to ceramics. It becomes possible to form a uniform and strong film on the surface of the base material. The composite thermal sprayed material of the present invention may be used in the form of granules of the composite thermal sprayed material. According to a composite thermal spray material made of granules, it is possible to adjust the particle size distribution of the thermal spray material over a wide range, reduce the scattering loss of the thermal spray material during thermal spraying work, and obtain a thermal spray material that provides a homogeneous and strong coating. becomes possible. The ceramic used in the present invention has high hardness and cannot be easily turned into fine powder by pulverization. For example, oxides such as alumina, titania, and zirconia, carbides such as silicon carbide, molybdenum carbide, tungsten carbide, zirconium carbide, chromium carbide, and titanium carbide, titanium nitride,
There are nitrides such as zirconium nitride, silicides such as chromium silicide and tungsten silicide, and borides such as chromium boride and zirconium boride. Metals include aluminum, nickel, copper, zinc, iron, cobalt, titanium, chromium, molybdenum, and alloys containing these as main components. These metals, like ceramics, have corrosion resistance, oxidation resistance,
It promotes heat resistance and abrasion resistance, and can be selected as appropriate depending on the type of substrate and the desired properties of the thermal sprayed coating. The above alloy may contain components such as vanadium, zirconium, yttrium, and tungsten depending on the purpose. The appropriate ratio of ceramic to metal is 0.1 to 1.0 times the metal by weight (90:10 to 50:50). Microscopic observation of the particles of the composite thermal spray material according to the present invention shows that the bond between the highly hard ceramic particles and the above-mentioned metal is such that the metal is stuck to the surface of the ceramic particle, and in the case of malleable metal, the metal is further bonded to the surface of the ceramic particle. It forms a forging bond that encompasses individual ceramic particles. The composite thermal spray material of the present invention is obtained by a so-called mechanical alloying method in which ceramic powder and metal powder are mixed and stirred in a ball mill and a strong impact force is applied. The mechanical alloying method is described, for example, in Japanese Patent Publication No. 37631/1983. Ceramic and metal are mixed in advance into powders of 70 μm or less and charged into a ball mill, and when a strong impact force is applied through the balls, the powder particles are pressed together. Since ceramic particles are hard, they do not break and particles with metal bonded to part of their surfaces can be obtained as shown in FIG. If the metal is relatively soft and malleable, if further impact force is applied, the metal adhering to the surface of the ceramic particle and new metal powder will form a forging bond and grow, as shown in Figure 2. Composite particles containing metal and ceramic particles are obtained. In the composite thermal sprayed material produced by the method of the present invention, since the ceramic particles are hard, they do not have a structure like a mechanical alloy in which dissimilar materials are interlocked with the entire particle, but a mechanical alloy-like structure in which metal is interlocked only on the surface. The particles become Powder particle cross section
When observed with EPMA, it can be seen that the interior is made of ceramic and metal components exist only on the surface. If the composite powder thus obtained is classified and adjusted to a particle size range suitable for the purpose of thermal spraying and the equipment used, it can be widely used as a material for powder thermal spraying such as gas thermal spraying and plasma thermal spraying. It is also possible to re-granulate the fine powder of this composite powder and adjust it to an appropriate particle size distribution before use. If the composite thermal spraying material of the present invention is used, a thermal sprayed coating consisting only of ceramic and metal and containing no other impurities can be obtained, and since a large amount of metal is used as a bond, it is possible to form a strong coating of ceramic on the surface of the base material. It becomes possible to do so. Furthermore, in the case of a ceramic such as boron carbide, which decomposes in a high temperature atmosphere where oxygen is present in excess, the surface metal has the function of protecting the ceramic. Next, when the powder particles of the composite thermal spray material made of granules are observed microscopically, as shown in FIG. 3, they form an amalgamation of composite particles of ceramic and metal.
This is a new composite thermal sprayed material whose composition is significantly different from that of the conventional composite thermal sprayed material shown in FIG. 4, which is composed of an aggregate of ceramic particles and metal particles. According to the present invention, even if the spray material dissociates into individual particles during the spraying process, the ceramic and metal still maintain a strong integral bond, so the resulting spray coating is homogeneous and strong. Become. With conventional composite sprayed materials, the sprayed coating was separated into a ceramic part and a metal part, so it was not strong. The composite thermal sprayed material consisting of granules is obtained by granulating the composite thermal sprayed material obtained according to the present invention by a conventional method. The powder used as a raw material may be the composite material according to the present invention as it is, or only fine particles obtained by classification may be used. As a granulation method, methods such as spray granulation, agitation granulation, and fluidized granulation using an organic or inorganic binder can be used. The granulation size is suitably 5 to 120 μm to suit powder spraying. After the granulated powder is dried or sintered, it is classified into a particle size range that meets the thermal spraying conditions and is used as a thermal spray material. If the composite thermal spray material according to the present invention is used, the ceramic and metal will not separate during the thermal spraying process, so a homogeneous and strong thermal spray coating can be obtained.
Further, since thermal spraying material having an appropriate particle size range can be used, the yield of thermal spraying material can be improved. Next, the present invention will be explained with reference to Examples. Example 1 Stabilized zirconia powder with a particle size of 44 μm or less and Ni (80%) with a particle size of 44 μm or less
Atomized powder of Cr (20%) alloy was mixed in an amount of 50 parts by weight, charged into a vertical ball mill (attritor), and mixed and stirred in an argon atmosphere. The rotation speed of the stirring blade was set to 500 rpm, and the mixture was stirred for about 4 hours to perform mixing, pulverization, binding, and dispersion. The average size of the obtained particles was 10 μm, and when the surfaces of the particles were observed, it was found that the metal was interlocked with the surface of each particle to form an integral bond. Next, using varnish as a binder, this powder was grown to a maximum particle size of about 75 μm by stirring granulation, and then dried at 120° C. for 10 minutes. The obtained powder was classified to 10 to 44 μm to obtain a thermal spray material. Using this thermal spray material, SUS304 (4mmt×38
mmW×50mml) Ni-Cr as a base thermal spray on the base material
The (80-20) alloy was sprayed to a thickness of 100 μm, and then sprayed to a thickness of 200 μm using a plasma spraying method. The thermal spraying conditions were as follows. Thermal spraying equipment Plasmadyne SG100 gun Argon gas flow rate 35l/min Current 750A Voltage 30V Powder supply rate 58g/min To examine the spalling resistance of the resulting thermal sprayed coating, the thermally sprayed test piece was heated to a specified temperature. After holding for 15 minutes, it was cooled in water. This heat treatment operation was repeated five times, and the state of peeling of the film was observed. For comparison, stabilized zirconia powder with a particle size of 10 to 20 μm and atomized Ni(80)-Cr(20) alloy powder were mixed, stirred and granulated using varnish as a binder, and then dried and granulated. A similar test was conducted using a thermal spray material classified into 10-44 μm particles and a simple mixed powder of 10-44 μm stabilized zirconia powder and Ni-Cr alloy atomized powder as a thermal spray material. These results are shown in Table 1.

[Table] As is clear from the results, it can be seen that a strong film is formed when the composite sprayed material according to the present invention is used. Example 2 Alumina powder with a particle size of 20 μm or less,
Carbonyl nickel powder and metallic boron powder with a particle size of 10 μm or less are mixed into alumina 90% by weight.
1 part, 5 parts of nickel powder, and 5 parts of boron powder were mixed and stirred in the same manner as in Example 1. The size of the obtained powder particles was 10 to 53 μm, and when the surfaces of the particles were observed, it was found that each particle had a metal mixture of nickel and boron interlocked with the surface of the alumina particles, forming an integral bond. . Next, use this powder as a thermal spraying material for base thermal spraying.
Thermal spraying was carried out in exactly the same manner as in Example 1, except that Ni(95)-Al(5) alloy was used, and the adhesive strength and spalling resistance of the obtained thermal sprayed coating were examined. The adhesive strength was determined by a tensile test on the film, and the spalling resistance test was performed in the same manner as in Example 1. For comparison, the same test was conducted using a mixture of alumina, carbonite, and boron powders with a particle size of 10 to 44 μm in the same weight ratio. These results are shown in Table 2.

[Table] As is clear from the results, a strong thermal sprayed coating can be obtained when the composite thermal sprayed material according to the present invention is used. Example 3 Boron carbide powder having a particle size of 44 μm or less and aluminum atomized powder were mixed at a weight ratio of 1:1, and mixed in the same manner as in Example 1. The average particle size of the obtained powder was 10 μm, and when the surfaces of the particles were observed, it was found that each particle was integrally bonded with aluminum surrounding the surface of boron carbide. Next, this powder was grown to a maximum particle size of about 90 μm in the same manner as in Example 1, dried, classified to a final particle size of 10 to 90 μm, used as a thermal spray material, and grown in the same manner as in Example 1. A thermal sprayed coating was obtained under these conditions. The surface condition of the obtained thermal sprayed coating was observed, and the adhesive strength of the coating was measured by a tensile test. Table 3 shows the results.
Shown below. For comparison, a powder obtained by simply mixing boron carbide powder of 10 μm or less and aluminum powder of 44 μm or less, and a powder obtained by granulating the mixed powder using varnish as a binder, drying, and classifying it into 10 to 90 μm were used. I took the test. These results are also listed in Table 3.

[Table] As is clear from the results, a strong thermal sprayed coating can be obtained by using the composite thermal spraying material of the present invention even if it cannot be thermally sprayed with a simple mixed powder. Example 4 Silicon carbide powder with a particle size of 25 μm or less and cobalt fine powder with a particle size of 10 μm or less in a weight ratio of 65:35
The mixture was mixed and stirred in the same manner as in Example 1. The average particle size of the obtained powder particles was 10 μm, and the cobalt was interlocked with the surface of the silicon carbide particles to form an integral bond. This powder was granulated in the same manner as in Example 1, dried, and then classified into particles of 10 to 44 μm to obtain a thermal spray material. Next, a thermal sprayed coating was made using this thermal spraying material under the same conditions as in Example 1, and the condition and adhesive strength of the obtained coating were examined. For comparison, similar tests were conducted using a powder obtained by simply mixing 10 to 44 μm silicon carbide powder and cobalt powder, and a powder obtained by coating the silicon carbide surface with about 5 wt % of cobalt using a salting-out method.
These results are shown in Table 4.

[Table] If a simple mixed powder is thermally sprayed, it will crumble and become unusable as a thermally sprayed coating.
If the composite thermal spray material according to the present invention is used, the thermal spraying efficiency will be significantly improved compared to the case where a coating powder is used, and a dense and strong thermal sprayed coating can be obtained. Example 5 Titanium carbide powder with a particle size of 25 μm or less and cobalt fine powder with a particle size of 10 μm or less in a weight ratio of 65:
35 parts, and mixed and stirred in the same manner as in Example 1. The average particle size of the obtained powder particles is 10μm
The cobalt meshed with the surface of the titanium carbide particles to form an integral bond. This powder was granulated in the same manner as in Example 1, dried, and then classified into particles of 20 to 44 μm to obtain a thermal spray material. Next, a thermal sprayed coating was made using this thermal spraying material under the same conditions as in Example 1, and the condition and adhesive strength of the obtained coating were examined. For comparison, similar tests were conducted using a powder obtained by simply mixing 10 to 44 μm titanium carbide powder and cobalt powder, and a powder obtained by coating the titanium carbide surface with about 5 wt % of cobalt using a salting-out method. These results are shown in Table 5.

[Table] A simple thermal sprayed mixed powder has poor adhesion to the base material. Those using coating powder do not have sufficient adhesive strength because the amount of cobalt as a binder is small. On the other hand, when the composite sprayed material according to the present invention is used, a dense and strong sprayed coating can be obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams illustrating the bonding state of ceramic particles and metal in the composite thermal spray material according to the present invention. FIG. 3 is a diagram showing powder particles of a composite thermal spray material according to the present invention, and FIG. 4 is a diagram showing powder particles of a conventional composite thermal spray material. 1...ceramic particles, 2...metal, 3...binder.

Claims (1)

[Claims] 1. Mixing ceramic particles selected from metal oxides, carbides, borides, and nitrides and a metal in a weight ratio of 0.1 to 1.0 times the weight of the ceramic particles, A method for producing a composite thermal spray material, characterized in that the mixed powder is stirred and mixed by applying high energy to form mechanical alloy-like particles in which ceramic and metal are mechanically interlocked and integrally bonded. 2 The ceramic particles are stabilized zirconia,
2. The method for producing a composite thermal spray material according to claim 1, wherein the metal is an alloy containing nickel and chromium as main components. 3. The method for producing a composite thermal spray material according to claim 1, wherein the ceramic particles are alumina and the metal is an alloy containing nickel and boron as main components. 4. The composite thermal spray material according to claim 1, wherein the ceramic particles are boron carbide, and the metal is nickel, aluminum, or one of alloys containing nickel and aluminum as main components. manufacturing method. 5. The method for producing a composite thermal spray material according to claim 1, wherein the ceramic particles are silicon carbide and the metal is cobalt. 6. The method for producing a composite thermal spray material according to claim 1, wherein the ceramic particles are titanium carbide and the metal is cobalt.