JPS6045269B2 - Ceramic powder material for thermal spraying - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic powder material for thermal spraying used for ceramic coating to impart wear resistance and other properties to the surface of metal materials, and more specifically, to By sintering at least one powder particle of a metallic substance on the surface of each of the hard ceramic particles of This invention relates to a ceramic powder material for thermal spraying that is improved so as to be able to form a strong ceramic coating layer.

In order to impart earth and sand wear resistance to members such as earth and sand wear parts for agricultural or civil engineering machinery, overlay thermal spraying is sometimes applied to harden the surface.

At that time, it is known to further impart wear resistance by dispersing and welding hard ceramic particles of an appropriate size into this thermal sprayed layer. The hard ceramic particles used at this time include metal carbides, oxides, or nitrides such as WC particles or TiC particles, but WC particles are usually used, and composite materials with metals such as Co are commonly used. It is common to thermally spray the powder using the powder spraying method. However, as W resources become unevenly distributed and depleted, the prices of WC particles become high, and the reality is that their use is restricted to products other than products with very high added value. Therefore, it has become difficult to perform thermal spraying on consumable parts and large parts as mentioned above. Aluminum oxide particles are available as hard particles that are inexpensive and abundant in resources, and exhibit sufficient wear resistance for practical use, in place of WC particles.

However, aluminum oxide particles cannot be bonded to the spraying base material even if they are sprayed individually using a powder spray gun. Further, even if a mixed powder obtained by mixing these particles with powder particles of a metallic substance is thermally sprayed by the above-mentioned powder spraying method using a heat source, these hard particles cannot be practically effectively adhered to the thermally sprayed base material. For this reason, aluminum oxide particles are not used in ordinary powder spraying methods, but are used as materials for advanced thermal spraying methods such as plasma spraying, wire spraying, and explosive spraying. However, these thermal spraying methods instantaneously spray high melting point particles as molten particles, and at extremely high temperatures (for example, 10,000°C to 1,600°C).
0'C), problems such as crystal shape transformation of hard particles occur during this extremely high temperature history, and heat from the spray heat source is transferred to the spray base material, adversely affecting the base material. may occur. Furthermore, it is necessary to form a sintered rod by molding and sintering the thermal spraying material, resulting in the use of expensive materials. In the present invention, particles made of aluminum oxide are thermally sprayed in the state of unmolten or semi-molten particles by a powder spraying method using a normal oxygen-acetylene flame or oxygen-hydrogen flame as a heat source. The object of the present invention is to provide a ceramic powder material for thermal spraying which is improved so that a thermal sprayed layer having sufficient adhesion strength to the thermal spraying layer can be obtained, and the means for improving the thermal spraying layer is a very simple method. That is, in the present invention, at least one powder particle of a metallic substance (the powder particle of the metallic substance is a powder of a single metal or an alloy) is sintered in advance on the surface of each particle for thermal spraying made of aluminum oxide. In this ceramic powder material for thermal spraying, the surface of the sintered metal powder particles becomes semi-molten or softened during thermal spraying, and this acts as an adhesive to the thermal spraying base material. This makes it possible to bond aluminum oxide particles, which has been difficult in the past. Here, the metal substance refers to a metal selected from Group 1, Group Ⅰ, Group Ⅲ metals of the periodic table of elements, and their alloys, and has a melting point lower than that of aluminum oxide particles, and its softening The temperature is between about 600°C and about 1300°C, and the metal material is selected depending on the material of the sprayed base material to be applied or the purpose of the sprayed product. Nickel, nickel-chromium alloy, nickel-copper alloy, copper, iron, iron-copper alloy, iron-nickel alloy, etc. are suitable.

These metallic materials are particularly advantageous because they readily form metallurgical bonds with the self-fusing alloys used in the reheat treatment. That is,
In the actual thermal spraying work using the product of the present invention, after applying an overcoat with a self-fusing alloy on the ceramic spray layer,
child! The most effective method is to reheat the material, and at this time, the self-fusing alloy and the metal material are firmly bonded to form a good sprayed layer. The practically advantageous particle size of the aluminum oxide particles used is approximately 50p.
m to about 300 μm, and the powder particle size of the metal material to be sintered on the surface is about 3 μm to about 300 μm.
A range of m is preferred, and at least one metal powder particle is sintered per one hard particle. This sintering does not require full-scale sintering in which the surface of the hard particles is covered with a metal substance, but it is sufficient to maintain a sintered state in which the metal substance always exists on the surface and moves together. To perform this sintering,
Temperature lower than the melting point of the metal substance used (abdominal point x 0.6
This can be suitably carried out by appropriately stirring the mixture of aluminum oxide particles and metal powder particles to a temperature of 0.8 to 0.8° C. while heating the mixture. The atmosphere for heat treatment may be normal air or air depending on the type of metal material used.
An inert gas, neutral gas or vacuum atmosphere is selected.
If the oxidation rate is slow and the heat treatment time is short and takes less than a few minutes, a normal atmospheric atmosphere may be used. In this case, the surface of the metal powder particles used is slightly oxidized, but after spraying the sprayed base material to form a sprayed layer, an overcoat with a self-fluxing alloy containing B and Si is applied, and this is reheated. By doing so, this oxide can be turned into a slag and removed. As described above, the manufacturing process of ceramic powder material for thermal spraying of the present invention is a simple and continuous process that is suitable for mass processing.

Particles made of aluminum oxide obtained through these processes are used as ceramic powder material for thermal spraying, and are sprayed with a normal powder spraying gun to form ceramic powder on the surface of the base material.
The thermal sprayed coating layer not only exhibits almost the same level of wear resistance as a thermal sprayed layer obtained by thermally spraying a commercially available thermal sprayed material with known WC particles as a substrate, but also has thermal spraying equipment and thermal spraying technology that are well known in the art. A powder spraying method using an acetylene or oxygen-hydrogen flame as a heat source can be applied as is. In addition, there is no need to apply a bonding coat to the base material for thermal spraying in advance, and the cost of thermal spraying materials is low, as well as improving work efficiency and providing an energy-saving thermal spraying method. Examples and usage effects of the present invention are described below, but these are representative examples, and the present invention is not limited to these examples in any way.

Example 1 A metal melting crucible made of magnesia special refractory is placed in a vacuum electric furnace adjusted to about 870°C, and abrasive grains (#120) of aluminum oxide artificial abrasive material (JISR6lll compliant product) are placed in the crucible. and 100 gr' of nickel powder (average diameter 30 μm) were thoroughly mixed and charged, and the mixture was kept for two hours.

During that time, stirring operations were performed three times. Approximately 100 in an electric furnace
After being gradually cooled to about 0.degree. C., it was taken out of the furnace and further cooled to room temperature. The obtained product was particles formed by sintering one or several pieces of nickel powder on the surface of each abrasive grain, but taking into consideration the spray aperture of the thermal spray gun, the coarse particles were removed using a sieve screen. Removed. This product was supplied as a ceramic powder material for thermal spraying to a powder thermal spraying device using an oxygen-acetylene flame as a heat source, and the surface was treated by sandblasting with a commercially available powder thermal spraying gun.Width 23n1/m x length 85rT1/M
Abrasive grains (#1
20) and commercially available self-fusing alloys (Nl-based Cr-B-Si system)
The adhesion rate of the abrasive grains to the test piece was determined for three test pieces, one in which a mixed material containing 5% of each was sprayed, and the other in which a single abrasive grain (#120) was sprayed, and the results were calculated as follows. It is shown in Table 1. Example 2 A soil and sand abrasion performance test was carried out using the wear parts sprayed with the product of the present invention of Example 1, and the results were as follows.

The test machine used was a commercially available hand-push rotary mower equipped with an engine with a maximum output of 3.5 PS/3600 r'pm and equipped with one rotary knife of diameter (a) d. One side of the blade (about 1? length) of the rotary knife of this power mower was surface-treated by sandblasting, and the product of the present invention was powder-sprayed, and then a commercially available self-fusing alloy (Ni
An overcoat was applied with a Cr--B--Si group and a reheating treatment was performed, but the sprayed layer thickness was about 0.7 m/m. The other blade part was subjected to the same surface treatment as described above, and a known thermal spray layer made of the same type of self-fluxing alloy was made to a thickness of about 0.7 m/m.
It was made into a l-blade. Surface treated NO. The two blades were coated with a commercially available WC-based self-melting alloy (40% WC) using a known powder spraying method.
The blade part is thermally sprayed with NO. A blade part was made by thermal spraying the same type of self-fluxing alloy as that used for the blade and had a sprayed layer of about 0.7 m/m thick, and was used as a comparative material. Each rotary knife has been carefully balanced for safety. These rotary knives were attached to the test machine, and while maintaining normal operating conditions, the rotary knife was operated continuously for 3 minutes while inputting and moving over the natural beach sand surface, with the rotary knife always making sufficient contact with the beach sand. , the presence or absence of chipping and peeling of the thermal sprayed layer on the blade was examined, but NO. l blade, NO. No abnormalities were observed on either of the two blades. Next, in order to determine the amount of wear on each thermal spray blade part, each rotary knife was cut on the rotation center line and NO. l-(A) (thermal spraying of the present invention), ND. l-(mouth) (self-fusing alloy spraying), NO. 2-(A) (40% WC self-fusing alloy thermal spraying)
, NO. 2- (mouth) (self-fusing alloy sprayed), 4 pieces,
The weight of each piece was measured. NO. l blade and NO. In order to eliminate subtle differences in the wear test conditions of the two blades, it was assumed that the wear amount of the self-fusing alloy sprayed layer under certain conditions was constant, and the weight difference between the pieces with the self-fusing alloy sprayed blades was calculated. was calculated and shown as the wear resistance rate in Table 2). As described above, the present invention is a ceramic powder material for thermal spraying formed by sintering powder particles of a metallic substance on the surface of each particle made of aluminum oxide, and is a ceramic powder material for thermal spraying that is formed by sintering powder particles of a metallic substance on the surface of each particle made of aluminum oxide. The powder spraying method, which uses hydrogen flame as a heat source, not only makes it easy to form a sprayed layer with strong wear resistance and other properties, but also reduces the cost of spraying materials and improves work efficiency, resulting in energy savings. This is a ceramic powder material for thermal spraying that can provide a sprayed layer of aluminum oxide particles using a thermal spraying method.

Claims (1)

[Claims] 1. A ceramic powder material for thermal spraying comprising at least one powder particle of a metallic substance sintered on the surface of each particle made of aluminum oxide.