JPH10147852A - Wc-co type thermal spraying material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means capable of obtaining a WC-Co type sprayed coating having an excellent density, wear resistance, and adhesion to a base material without further treatment. SOLUTION: This thermal spraying material is prepared by mixing an Ni-P alloy powder containing 5-15wt.% P with a WC-Co type powder. In this thermal spraying material, a liquid phase of Ni-P alloy appears at 950-1050 deg.C. Accordingly, at the time of sintering the thermal spraying material, WC grains are allowed to enter into solid solution in a binding phase consisting of Co, Ni, and P and a firmly bound WC-Co type thermal spraying material can be formed. Further, the liquid phase of Ni-P alloy exists even after plasma thermal spraying, and pores in the coating are reduced and binding among the grains can be strengthened. As a result, the coating, having satisfactory denseness characteristic in an as-thermally-sprayed state without densification treatment after thermal spraying and also having sufficient water resistance, can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sprayed WC-Co material for forming a thermal sprayed wear-resistant coating.

[0002] In the present invention, the WC-Co system basically means
It means an alloy system composed of WC particles forming hard particles and Co forming a binder phase that binds between the hard particles. In addition to this basic structure, part of the WC particles that are hard particles is replaced with another TiC. , TaC, NbC, or other carbide particles, and a part of Co forming a binder phase is replaced with Fe, N
It can be replaced with an iron group metal such as i.

[0003]

2. Description of the Related Art Conventionally, it has been widely known that a wear-resistant film is formed by plasma spraying using a WC-Co-based material, but usually, after spraying, the density of the sprayed film is increased. , 1000 ° C. or more to perform the densification treatment. However, the densification treatment involves an extra step, so that the production efficiency is low, and the thermal influence on the base material is large, so that its application range is limited.

Further, the inventor of this application is Nippon
Tungsten Review, Vol. Fifteen
(1982). In order to omit this densification treatment, a Ni-P alloy forming powder is thinly coated on the surface on which the thermal spray coating is formed, and heated to form a Ni-P alloy coating.
It is described that a hard thermal spray coating is formed thereon.

However, for the purpose of densification, it is necessary to incorporate about 30% by weight of a Ni-P alloy forming powder for forming a binder phase. Therefore, the hardness of the sprayed coating is high but the toughness is poor. Heating temperature during composite powder production is Ni-P
Since the temperature is lower than the liquidus temperature of the alloy, diffusion and solid solution between WC and the Ni-P alloy are not perfect, and the wear resistance of the sprayed coating is insufficient.

[0006]

The problem to be solved by the present invention is to obtain a WC-Co-based thermal sprayed coating having excellent denseness, abrasion resistance and adhesion to a substrate in a sprayed state. Is to find a way to do it.

[0007]

The present invention provides a WC-Co.
This is a thermal spray material in which a Ni-P alloy powder containing 5 to 15 wt% of P is blended with a base powder.

[0008] In this thermal spray material, a liquid phase of the Ni-P alloy appears at a temperature of 950 to 1050 ° C. Therefore, the WC and the binder phase are firmly bonded during the thermal spray powder production process of sintering and pulverization. Even after the plasma spraying, the Ni-P alloy liquid is cooled until the thermal spray coating falls to about 900 ° C. The presence of a phase reduces the porosity of the coating and enhances the bonding between the particles. Further, in the liquid phase of the Ni-P alloy, WC as a basic component and Co as a binder phase form a solid solution, and WC and C
and o are firmly bonded. Therefore, even if the thermal spraying is performed, it is possible to form a film having a sufficient density and a sufficient abrasion resistance without performing a densification treatment after the thermal spraying.

When the content of P in the Ni-P alloy is less than 5% by weight, the formation of a liquid phase is small, the solid solution amount of WC and Co in the liquid phase is reduced, and the strength of the thermal spray coating is reduced. If the content is more than 20% by weight, the strength and wear resistance of the thermal sprayed coating are reduced due to the brittleness of the Ni-P alloy itself.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In producing a thermal spray material according to the present invention, WC powder, Co powder, and Ni-P alloy powder are sufficiently mixed in a predetermined mixing ratio by a ball mill, and a hydrogen atmosphere electric furnace or a vacuum furnace is used. Over 900 ° C and 1050 ° C
Sinter at the following temperature. This sintering temperature is also defined by the content of P in the Ni-P alloy, but if this P content is present, a liquid phase is generated at a temperature within this range, and a part of the WC particles is partially removed. It dissolves in this liquid phase.

[0011] The particle size of the thermal spray material of the present invention is appropriate from -200 to +400 mesh from the viewpoint of mobility to the thermal spray nozzle.

[0012]

EXAMPLES The powders of WC, Co, and Ni-P alloys having the composition shown in Examples 1 to 5 in Table 1 were mixed by a ball mill, filled in a carbon boat, and charged in a hydrogen-free electric furnace. After sintering for 2 hours each at the temperature described in 1,
Pulverized with a stamp mill and -200 to +40
A WC-Co- (Ni-P) composite powder of 0 mesh was obtained. Using this composite powder, plasma spraying is performed to about 2 m
Thus, a sprayed coating having a thickness of m was obtained.

Table 2 shows the thermal spraying conditions of each embodiment. The sprayed coating thus formed was not subjected to any post-treatment, and its hardness, the results of an abrasive wear test (load: 3 kgf, number of frictions: 2,800 times), and the coating by a thin film adhesion strength measuring device (Sebastian IV type) The results of measuring the adhesion strength are shown in Table 1 together with the production conditions of the thermal spray material.

For comparison, a thermal spray coating was formed using a conventional thermal spray material, and the same tests as those of the embodiment of the present invention were conducted. The results are shown in Table 1. Comparative Examples 1 and 2 correspond to Example 1.
Thermal spraying was performed under the same thermal spraying conditions as in Example 5, and Comparative Example 3 was performed under the same thermal spraying conditions as in Example 5.

When the results of this example were compared with the comparative examples, all of hardness, abrasion resistance, and adhesion were satisfactory. The WC-Co of Comparative Example 1 is excellent in abrasion resistance and adhesion. In Comparative Example 2, the binder phase was Ni-P
Sintering temperature for powder production is 880 ° with only alloy phase
C. In this case, the abrasion resistance is improved as compared with Comparative Example 1, but the toughness is poor, and in each of the examples, each is more excellent than Comparative Example 2. Further, in the case of Comparative Example 3, the post-treatment had a large thermal effect and there was a problem in durability.

[0016]

[Table 1]

[Table 2]

[0017]

The thermal spray coating obtained by using the thermal spray material according to the present invention has abrasion resistance comparable to that of the WC-Co coating which has been densified as it is sprayed, has good adhesion to the substrate, and has good heat treatment. This is advantageous in terms of cost because it is not necessary to perform the method, and the applicable range of the base material is wide.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Hayashi 1-44-1 Mason de Kashii 204, Kashii Station, Higashi-ku, Fukuoka (72) Inventor Osamu Nakano 1-2-8 Minojima, Hakata-ku, Fukuoka Japan Japan Inside Tungsten Co., Ltd.

Claims (3)

[Claims] 1. A WC-Co powder and P in an amount of 5 to 15 wt%.
Thermal spray material containing Ni-P alloy powder. 2. The thermal spray material according to claim 1, wherein the WC hard particles have a composite phase partially dissolved in a binder phase composed of Co, Ni and P. 3. An amount of 5 to 15 wt% of WC-Co powder and P.
After sintering the mixed powder with the contained Ni-P alloy powder at a temperature of 900 ° C. or more, this sintered product is subjected to −200 to +4.
A method for producing a thermal spray material that is crushed to 00 mesh.