JPS6051550B2 - Surface coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of forming a coating layer or a diffused surface layer on a predetermined machined surface by passing a large current through a wire electrode between opposing electrodes and causing a so-called discharge explosion. In particular, it relates to a coating method using a rare earth alloy as a wire for a wire electrode.

Conventionally, a method of forming a coating layer by wire explosion on a predetermined treated surface, for example, a method of coating a hard metal on the inner surface of a cylinder, is to make a wire with metals such as tungsten, titanium, molybdenum, or their carbides, and coat the inner surface of the cylinder with a wire. Electrodes with opposing gaps of a certain length are provided at predetermined locations of the cylinder, and a large current is instantaneously passed between the electrodes to cause a so-called discharge explosion, and the ejected dissolved particles are placed at a predetermined location on the inner surface of the cylinder. It is known to form a covering hard metal layer by impact welding or to form a diffused surface layer.

Additionally, alloy coatings of copper and cobalt that provide conductivity and magnetism are also known. The method of thermally spraying a specific metal using such discharge explosion must be carried out under appropriate requirements depending on the applied material and application conditions. now,
The deposited metal coating or metal-diffused layer has improved heat resistance, enhanced wear resistance, increased corrosion resistance, improved stress corrosion resistance, increased hardness, and increased elasticity over the welded layer. In some cases, it can also be achieved in cases where activation of the necessary catalyst or provision of ease of discharge is required, and in some or most of these, it is possible to achieve remarkable effects. If we can demonstrate this, there will be expectations that it will be a wonderful thing. However, it cannot be said that this goal can be easily achieved using conventional proposals. In view of the above-mentioned current situation, the present invention aims to provide a method that can meet these expectations and can be used very effectively in practice.

To achieve this object, the present invention uses rare earth alloys, rare earth alloys containing rare earth oxides, formation of coating layers or diffusion layers by discharge explosion of metals used as electrode wires, and The atmosphere activity during the formation of these layers is controlled to make it more effective. No sufficient proposals have been made regarding the formation of such alloys based on weld metals and rare earth elements, and the formation of thermally sprayed layers of such wires. Next, an outline of the present invention will be explained.

Examples of rare earth elements include rare earth elements. Among these, the present invention makes practical use of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, and Mitsushi metal. An alloy containing one or more elements arbitrarily selected from these in a proportion in the range of 0.1 to 1% is added to the metal to be welded,
For example, it is manufactured by containing one or more of the above-mentioned tungsten, molybdenum, titanium, or their carbides or nitrides, and used as an electrode wire in a predetermined shape. Regarding the above-mentioned range of 0.1 to 20 Wt%, if the content is 20% or more, the activity becomes high and oxidation is likely to occur, so 20% is the upper limit.

Moreover, since no effect is observed below 0.1 Wt%, this is the lower limit. Generally, preferably 0.5 to 15
Wt% range, which range to choose is
Determined based on usage and allowable costs. As an alloy with molybdenum, the content of Mitsushi metal consisting of lanthanum, cerium, praseodymium, samarium, and neodymium is 5 to 1? An electrode wire made by permeating and diffusing a mixture of t% and the balance being molybdenum was used. Explosive thermal spraying formed the coating layer in an inert atmosphere. In this case, the molybdenum wire. It was confirmed that compared to the explosive sprayed coating layer, the electron emission characteristics require a lower discharge voltage, and those containing rare earth elements are easier to discharge.
Furthermore, a coating layer with significantly improved heat resistance, corrosion resistance, and stress corrosion resistance was obtained. Diffusion formed on the surface of a copper alloy plate by line explosion spraying in the atmosphere using an electrode wire of an alloy containing scandium, lanthanum, and cerium in a combined amount of 1.5 to 5 Wt%, with the remainder being copper. The coating layer may require a low discharge voltage, has improved elasticity, and shows changes in frictional resistance that can be controlled depending on the amount of rare earth.

The total of cerium, lanthanum, and samarium is 0.5~
The coating layer formed on the surface of an aluminum-silicon alloy plate by line explosion spraying in the atmosphere using a wire containing a mixture of 3 Wt% and titanium, the remainder being titanium, has heat resistance. Corrosion resistance was improved and hardness increased.

It is obtained by explosive spraying in the atmosphere using a wire electrode formed by permeating and diffusing a mixture containing 0.5 to 1.0 wt% of metal and the remainder consisting of titanium and titanium carbide. It was observed that the hardness of the coated layer was uniformly increased, the wear resistance was improved, and the elasticity was improved.

Using a sintered wire of a mixture of 0.5 to 1.0 Wt% of Mitsushi metal, 0.5 Wt% of cerium oxide and 3% of cobalt, and the balance being tungsten, the same procedure as above was performed except that the atmosphere was an inert gas. The covering layer formed as a middle layer is
Low discharge voltage, improved hardness and wear resistance, and good corrosion resistance.

The coating layer formed in an inert gas using an electrode wire containing 10 wt% of Mitsushi metal, 5 wt% of lanthanum and cerium oxide, and the balance being an alloy of molybdenum has a lower discharge voltage and a lower hardness. , improved corrosion resistance, and increased elasticity.

When the atmosphere was air, there were cases where the constant value was not stable. In either case, a common conclusion can be drawn. , Vermilion has a dense coating layer, lowers discharge voltage, increases hardness, improves elasticity, and improves corrosion resistance, heat resistance, and abrasion resistance.

Furthermore, it was observed that the stress corrosion resistance of the coating layer formed on the stainless steel plate surface and the copper alloy plate surface increased.

The findings derived from the results of these series of tests are that when the content of rare earth elements or Mitsushi metals is 20 Wt% or more, the activity is high, and unless linear explosion spraying is performed in an inert gas, there is a negative effect due to oxidation. becomes noticeable.

It is clear from the above example that the addition of rare earth element oxides also brings about good results in modification, but even if the addition is less than 20%, it can be carried out in an inert gas depending on the application and if necessary. gives more stable results. The results vary depending on the added content of rare earth elements or metals, and the atmosphere in which the process is carried out.

The difference between the results of alloying and the results of forming a composite, such as a sintered body, by permeation-diffusion treatment of the mixture is not particularly noticeable. . This means that even if an alloy electrode wire is not used, it is sufficient to obtain an electrode wire that can easily maintain its shape as an electrode wire and can flow a discharge current to the extent that it can be explosively sprayed. From this series of studies, we have found that properties that involve complex factors such as wear resistance, corrosion resistance, heat resistance, elasticity,
It is expected that various properties such as stress corrosion resistance can be adjusted and controlled by adjusting the amount of the rare earth element or Mitsushi metal added, the mixture of the rare earth element oxide therein, and the selection of the atmosphere.

As explained above, the present invention allows the weld metal to have a
The coating layer is extremely useful when the electrode wire is formed by containing rare earth elements and Mitsushi metal within the range of 20 Wt%, and a thermal spray coating is formed by instantly passing a large wire explosion current between the electrodes on the surface to be processed. It shows a certain characteristic.

The effect of lowering the discharge voltage, that is, making it easier to explode the wire due to energization. It also improves heat resistance, corrosion resistance, and stress corrosion resistance. Increases hardness. Increases elasticity. Improves wear resistance. It is expected that these conditions can be controlled by adjusting the applied atmosphere and the added content of rare earth elements. Using Mitsushi Metal has the same effect.

Claims (1)

[Claims] 1. An electrode wire is attached between opposing electrode wires, a large current is passed between both electrodes, the wire is instantly exploded, and the electrode wire metal is thermally sprayed and adhered to the workpiece surface to form a coating layer. In the above-mentioned electrode wire, the main component metal of the metal forming the coating layer and 0.1 to 20 wt% of the total composition of rare earth elements or metals are alloyed or mixed to prevent percolation and diffusion. A surface coating method in which electrode wires are bonded and integrated through processing, and then electrode wires are formed and fixed between the electrodes, and a predetermined large current is passed to form a coating layer or a diffusion coating layer on the workpiece surface by electrode wire explosive spraying. 2. The first aspect of claim 1 using an electrode wire having a composition in which an appropriate amount of these oxides is added to 0.1 to 20 wt% of rare earth elements or metals contained in the entire composition.
The surface coating method described in Section. 3. The surface coating method according to claim 1, wherein the wire explosion of the electrode wire is performed in the atmosphere. 4. The surface coating method according to claim 1, wherein the wire explosion of the electrode wire is performed in an inert atmosphere.