JPS62171927A - Molybdenum electrode for melting glass and production thereof - Google Patents

Abstract

PURPOSE:To obtain a molybdenum electrode suitable for melting glass simply and in good mass productivity, by forming a dense molybdenum silicide in improved adhesivity on the surface of a base of electrode made of Mo by the use of flame spray method in a low-pressure inert gas atmosphere. CONSTITUTION:The surface of base of electrode made of molybdenum is preferably treated by blasting, etc., set in a low-pressure flame spray device and a molybdenum silicide having >=85% density ratio to theory is formed on the surface of base of electrode by applying flame spray method carried out in a low-pressure inert gas atmosphere at 50-500Torr to give the aimed molybdenum electrode for melting glass. After low-pressure flame spray process is over, the base with the formed coated layer of molybdenum silicide is heat- treated at about 900-1,200 deg.C so that crystal bond strength of the molybdenum silicide layer can be further improved.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a molybdenum electrode for melting glass and a method for manufacturing the same, and more specifically, the present invention relates to a molybdenum silicide electrode that is dense on its surface and has good adhesion to a molybdenum substrate. The present invention relates to a molybdenum electrode for melting glass having a layer, and a manufacturing method that allows the electrode to be easily manufactured in one step.

[Technical background of the invention and its problems 1 Molybdenum (Mo) electrodes used for glass melting prevent the quality of molten glass from deteriorating due to falling of MO crystals from the surface of the MO material during use, and , to prevent oxidation of Mo material or erosion by molten glass, thereby maintaining the quality of molten glass and extending the life of the electrode.
Attempts have been made to form a coating layer made of molybdenum silicide (MoSi2), which has oxidation resistance and glass erosion resistance, on the surface and put it into practical use.

When forming such MoS+2, the so-called surface silicification method, CVD method, which directly reacts SN on the Mo substrate, is usually used.
The usual thermal spraying method carried out in the atmosphere, and the method of coating MoSi powder on the surface of the MO substrate and then baking it, etc., have been applied.

However, these methods require that the obtained MOS
i 2 The soundness of the coating layer is low. Specifically, the surface silicification method cannot obtain a coating layer with a uniform composition, and the CV
In the case of method D, it is quite difficult to obtain a coating layer with a thickness that is effective as a protective layer, and in the case of ordinary thermal spraying, the porosity is large and oxide entrainment occurs. Further, there are problems such as the coating layer not being dense, and problems such as the complicated process and lack of mass productivity.

[Object of the invention] The present invention solves the problems of the conventional art and provides a molybdenum electrode for melting glass having a dense and highly sound MOS I2 coating layer, and a method for mass-producing the same through simple steps. With the goal.

[Summary of the Invention] The present inventors have obtained the following knowledge while conducting intensive research to achieve the above object. That is, among the conventional coating layer forming methods described above, the thermal spraying method has the advantage of being easy to work with and can form a thick film in a short time, so that it does not meet the above-mentioned object of the present invention in terms of process. However, there is a disadvantage that the obtained MoS+2 layer is porous and cannot perform a sufficient function as a covering layer.

Therefore, the present inventors believe that by applying a low-pressure thermal spraying method, that is, a thermal spraying method in a low-pressure inert gas atmosphere, instead of the thermal spraying method performed in the atmosphere as described above, the process of the solvent method described above can be improved. Considering that it is possible to obtain a dense and highly sound coating while making full use of these advantages, the present invention was completed by finding the optimum conditions, especially the pressure of the inert gas.

That is, the molybdenum electrode for glass melting of the present invention is a molybdenum electrode for glass melting that is composed of an electrode base made of molybdenum and a molybdenum silicide coating layer formed on the surface of the base, and the coating layer is It is characterized by being a sprayed molybdenum silicide layer with a density ratio of 85% or more, and its manufacturing method involves applying a pressure of 50% to the surface of an electrode base made of molybdenum.
The method is characterized by including a step of forming a molybdenum silicide layer by applying a thermal spraying method in an inert gas atmosphere of 0 to 500 Torr.

As mentioned above, the molybdenum electrode for glass melting of the present invention has MO as a coating layer on the surface of the electrode base made of MO.
A thermally sprayed layer made of S I 2 is formed. The thermal sprayed layer needs to have a theoretical density ratio of 85% or more. If the theoretical density ratio is less than 85%, the electrode base will be eroded by the molten glass and cannot function as a covering layer sufficiently.

Further, this coating layer is formed by applying a low-pressure thermal spraying method as described later, and the layer thickness is not particularly limited, but is usually about 0.2 to 5 mm.

Next, a method for manufacturing a Mo electrode for melting glass according to the present invention will be explained.

The method of the present invention is based on the step of forming an MO312 coating layer on the surface of an electrode substrate made of MO by applying a low-pressure spraying method. For example, it is preferable to perform honing on the surface of the electrode base in order to improve the adhesion between the electrode base and the coating layer. Specifically, for example, a blasting process using 20 to 70 meshes of AM203 powder or GO granule powder at a blasting pressure of about 3 to 10 kg/cm2 can be applied.

The subsequent low-pressure thermal spraying process is performed in a low-pressure inert gas atmosphere using MoSi 2 powder as a raw material powder. The type of inert gas used at this time is helium (
Examples include He), argon (Ar), or a mixture thereof. The pressure of this inert gas is 50~
500 Torr, preferably 200-300 Torr
It is necessary to set it to . If this gas pressure is less than 50 Torr, the carrier gas used for thermal spraying may not be able to be used sufficiently or the raw material powder may scatter.
On the other hand, if it exceeds 500 Tart, the density within the sprayed layer will decrease. Furthermore, the particle size of the raw material powder is 20 to 10
It is preferable to use one with a value of about 0-.

Specifically, this step can be carried out using a low-pressure thermal spraying device. That is, first, the inside of the chamber is evacuated to a vacuum of 1 Torr or less using an air conditioner 17, and then an inert gas, which is an atmosphere waste, is blown into the chamber to a predetermined pressure. Then, Ar gas is introduced into the solvent gun as a plasma arc gas, and the spray gun generates a plasma arc.The raw material powder is supplied to the spray gun by the powder supply device, and is melted by the plasma arc, while the substrate is heated. Solvent on the surface. At this time, the surface temperature of the substrate was set to 200. ~80
It is preferable to maintain it at about 0'O.

After completing the low-pressure solvent treatment, heat treatment of the substrate on which the MoSi2 coating layer has been formed at a temperature of 900° to 1200°C is effective because it can increase the crystal bonding strength of the MoSi2 layer. It is. Also, this MoSi
The crystal bond strength can also be increased by methods such as electron beam irradiation or laser irradiation on the two layers.

[Example 1 of the invention Example FIL Pt 50 mm, -M 81000 mm
The Mo electrode substrate surface of #30 (7) GC abrasive grains and water mixture -7゛ Noras I, pressure 7kg/cm2 conditions (from J-H = -J-, Ng treatment cape L TaC7) are shown. In Section 4!1, low-pressure dissolution of MoSi2 powder was performed. For thermal spraying, we use all commercially available normal low-pressure thermal spraying equipment, and
The o Si 2 powder used was of the order of 30-75 μm in all cases. The surface temperature of the substrate was set at 100'O. Then, thermal spraying - [After finishing the culm, in vacuum, 900'
Heat treatment was carried out at O. The obtained M o S i
Layer thickness It of two layers 1. , there was a 5mm hole.

M of the M O electrode for melting 41 molecules obtained in this way
o The theoretical density ratio (%) of the S + 2 coating layer was measured and shown in Table 1, and the corrosion resistance when this electrode was actually used for glass melting. 111 was written in the table based on a survey of 1 family.

Comparative example 1? Evaluations similar to those in Example 1-1 were made for Mo electrodes that were completely formed as MoSi 2 layers by conventional thermal spraying at atmospheric pressure (applying Comparative Example 2). The results are shown in the table], 7.

Furthermore, the m-productivity of each Example and Comparative Example was evaluated by calculating the time required for production using 1 and 12, and the results are shown in the table.

[Effects of the Invention] As is clear from the following explanation, the molybdenum electrode for glass melting of the present invention has extremely dense MOS i on its surface.
It has two coating layers, and its manufacturing method is simple in terms of process, requires a short manufacturing time, and is highly suitable for mass production. In other words, the method of the present invention provides a high-quality coating layer that cannot be achieved with the conventional atmospheric pressure dissolution method, as well as CVD.
It also satisfies the high level of mass production that cannot be achieved by the method, and therefore its secondary value is great.

Claims (2)

[Claims] (1) A molybdenum electrode for glass melting consisting of an electrode base made of molybdenum and a molybdenum silicide coating layer formed on the surface of the base, the coating layer having a theoretical density ratio of 8.
A molybdenum electrode for melting glass, characterized by a sprayed layer of molybdenum silicide containing 5% or more. (2) Apply a pressure of 50~ to the surface of the electrode base made of molybdenum.
A method for manufacturing a molybdenum electrode for melting glass, comprising the step of forming a molybdenum silicide layer by applying a thermal spraying method in an inert gas atmosphere of 500 Torr.