JPH10183268A - Nickel-zinc master alloy and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce an Ni-Zn master alloy in which the evaporation and oxidation of Zn are prevented and having a prescribed compsn., at the time of producing an Ni-Zn master alloy for regulating the compsn. of a hot dip galvanizing bath, by adding Ni under melting at a specified temp. or below while the surface of hot dip Zn is isolated from air with carbon dioxide or the like. SOLUTION: At the time of producing an Ni-Zn master alloy composed of <10% Ni, <1.8% Pd, <0.1% Fe, <0.5% Cd, and the balance Zn for regulating the components in a hot dip galvanizing bath, the surface of hot dip Zn is coated with carbon dioxide to prevent its contact with air. Or, the surface of the hot dip Zn is coated with coke, charcoal, carbon or the to evade its contact with oxygen in air. Or, SF6 , air contg. SF6 or a gaseous mixture of SF6 -contg. air and gaseous CO2 is flowed through the surface of the hot dip Zn to form oxidation preventive coating. In this way, by adding Ni under melting at <=850 deg.C while the surface of the hot dip Zn is isolated from air, the Ni-Zn master alloy the from the evaporation and oxidation of Zn and high in an Ni content can stably be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a zinc master alloy containing nickel, for adjusting the bath composition of a galvanizing bath when applying a hot dip galvanizing treatment to impart corrosion resistance to the surface of a steel material, and The present invention relates to a zinc-containing zinc master alloy having a content of 10% by weight or less and used for producing a zinc alloy containing:

[0002]

2. Description of the Related Art Steel materials containing silicon and phosphorus, which are so-called killed steel materials, are used for general structures and the like. Generally, plating is performed. However, when plating is performed using a bath containing only zinc, an iron-zinc alloy layer having poor corrosion resistance develops abnormally, causing burnt loss of luster and a phenomenon such as a partial increase in zinc adhesion. I do.

As a countermeasure against such a phenomenon, for example, it is known that a plating method using a zinc bath containing 0.05 to 0.2% by weight of nickel is effective. However, if the plating operation is continued, the components of the plating bath are carried away by the plated material, and it is necessary to supply zinc and nickel by that amount. Even if a nickel base metal is introduced into the plating bath to maintain the bath composition of 0.05 to 0.2% by weight nickel, the melting point of nickel is 1455 ° C., and the temperature is rapid at a normal plating bath temperature of 430 ° C. to 500 ° C. Dissolution is not possible.

For this reason, a bath composition is generally adjusted using a nickel-zinc mother alloy of 2 to 3% by weight. However, a master alloy of 2 to 3% by weight of nickel-zinc requires a master alloy of about 1/10 to 1/30 with respect to the amount of the zinc bath, so that the amount of input during operation increases and the amount of the required mother alloy also increases. More and less economical.

Next, many zinc alloys containing nickel have excellent mechanical strength, and are commonly used. However, in the production of nickel-containing zinc alloys, nickel metal is directly injected into a zinc alloy melt. Is also difficult to alloy,
Use of a master alloy having a low nickel content is not economical, and a master alloy having a high nickel content has been desired. However, in order to melt a master alloy having a high nickel content, the molten zinc must be held at a high temperature for a long time, and it is difficult to melt in the atmosphere because zinc evaporates and burns.

In order to suppress the combustion, fluxes containing chlorides and fluorides have been used in the past. However, there is a risk that the fluxes may be entrained in the product, and the melting tool is severely damaged, and furthermore, environmentally friendly. There is also a problem.

The present invention solves such a problem and solves the problem.
An object of the present invention is to provide a nickel-zinc master alloy having a weight of 0% or less and a method for producing the same.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve such problems, and as a result, in order to suppress the evaporative combustion of zinc in the atmosphere, the surface of the molten metal is covered with carbon dioxide gas to form air. Avoid contact with air, cover the surface of molten metal with carbide such as coke, charcoal, carbon, etc., and avoid contact between oxygen and molten metal in air, sulfur hexafluoride, air containing sulfur hexafluoride or air containing sulfur hexafluoride An antioxidant film is formed on the surface of the zinc melt using either a mixed gas of carbon and carbon dioxide, and the surface of the zinc melt is covered with carbon dioxide, such as coke, charcoal, and carbon, and the contact between oxygen in the air and the melt is prevented. Avoid, cover the surface of the zinc melt with carbides such as coke, charcoal, carbon, etc., and further flow either sulfur hexafluoride, air containing sulfur hexafluoride, or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas. By zinc melt table The oxidation film is formed found a production method of dissolving nickel in zinc to, and have completed the present invention.

The first method for producing a nickel-zinc master alloy according to the present invention comprises not more than 10% by weight of nickel, not more than 1.8% by weight of lead, not more than 0.1% by weight of iron, and not more than 0.5% by weight of cadmium. Hereinafter, in the production of a nickel-zinc master alloy consisting of the remaining zinc and unavoidable impurities, the surface of the molten zinc is covered with carbon dioxide gas and kept at a temperature of 850 ° C. or less until the nickel is completely dissolved while cutting off contact with air. It is characterized by.

A second method for producing a nickel-zinc master alloy according to the present invention comprises 10% by weight or less of nickel, 1.8% by weight or less of lead, 0.1% by weight or less of iron, and 0.5% by weight of cadmium. Hereinafter, in the production of a nickel-zinc master alloy consisting of the remaining zinc and unavoidable impurities, the surface of the molten zinc is coated with coke, charcoal,
It is characterized by covering with a carbide such as carbon and maintaining the temperature at 850 ° C. or lower until the nickel is completely dissolved while cutting off the contact between the molten zinc and oxygen in the air.

A third method for producing a nickel-zinc master alloy according to the present invention comprises not more than 10% by weight of nickel, not more than 1.8% by weight of lead, not more than 0.1% by weight of iron, and not more than 0.5% by weight of cadmium. Hereinafter, in melting the nickel-zinc master alloy composed of zinc and unavoidable impurities, any one of sulfur hexafluoride, air containing sulfur hexafluoride, or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas is used. Is flowed to form an antioxidant film on the surface of the molten zinc, and is held at a temperature of 850 ° C. or lower until nickel is completely dissolved.

A fourth method for producing a nickel-zinc master alloy according to the present invention is the method for producing a nickel-zinc master alloy according to the second method, further comprising the step of: It is characterized by covering the surface.

In a fifth method for producing a nickel-zinc master alloy according to the present invention, the surface of the molten zinc is covered with a carbide such as coke, charcoal, carbon, or the like to cut off the contact with air, or thereafter, to sulfur hexafluoride or hexafluorocarbon. The method is characterized in that an antioxidant film is formed on the surface of the molten zinc by flowing either one of air containing sulfur fluoride or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas.

On the other hand, the nickel-zinc master alloy of the present invention comprises:
It is characterized by being manufactured by the first to fifth methods.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail.

The zinc alloy of nickel 10% is nickel 1
As shown in FIG. 1 showing the dissolution state of a zinc alloy of 0% or less, the temperature at which nickel and zinc completely melt in a liquid state (liquidus temperature) is 780 ° C., but the melting point of nickel is 1%.
The melting point of zinc is 455 ° C and the melting point of zinc is 420 ° C, and a temperature of about 850 ° C is actually required for alloying.

However, since the vapor pressure of zinc is high (7
When the temperature is raised in the atmosphere, zinc evaporates and burns, so it is difficult to raise the molten zinc to 850 ° C. The present inventors have noticed that combustion can be suppressed by shutting off the molten zinc and the atmosphere, and have found that carbon dioxide or the like can be used for such a purpose.

That is, carbon dioxide has a specific gravity of 1.5 times that of air, and exists between air and the surface of the molten metal, and can isolate them. Also, when the temperature rises, the carbon dioxide gas partially reacts on the surface of the molten zinc to become carbon monoxide,
Further, it has a combustion preventing effect. Further, the zinc oxide on the surface of the molten zinc produced by reacting with the carbon dioxide gas covers the surface of the molten zinc and helps to prevent the combustion of zinc. In addition, intense stirring of the melt at 750 ° C. or higher is not preferable because the surface of a new melt reacts with carbon dioxide gas.

Further, the surface of the molten zinc may be covered with a carbon-based carbide such as coke, charcoal or carbon without using carbon dioxide gas. In this case, the carbide is combined with oxygen in the air in the molten zinc to form carbon monoxide or carbon dioxide gas, and covers the surface of the molten zinc, thereby blocking the air from the molten zinc and preventing combustion. in this case,
It is necessary to replenish the above-mentioned carbide consumption.

Further, instead of carbon dioxide and carbide, 1
100% sulfur hexafluoride (SF ₆₎ or sulfur hexafluoride may be caused to flow air containing. This is because, by flowing the air containing sulfur hexafluoride, the sulfur hexafluoride forms an antioxidant film on the surface of the molten zinc, and the antioxidant film prevents combustion of the molten zinc. Since this antioxidant film breaks when the molten metal is stirred, vigorous stirring at 750 ° C. or higher is not preferable. Further, the above-mentioned mixed gas of carbon dioxide and air is used as the air containing sulfur hexafluoride, and the effect of preventing oxidation is further improved by the combined effect of the carbon dioxide and sulfur hexafluoride.

The synergistic effect can be enhanced by covering the surface of the molten zinc by using carbon dioxide in combination with the above-mentioned carbides such as coke, charcoal and carbon. Further, the surface of the molten zinc is covered with a carbide such as coke, charcoal, carbon or the like to cut off the contact with air, or simultaneously with sulfur hexafluoride, air containing sulfur hexafluoride, or air containing sulfur hexafluoride and carbon dioxide gas. The synergistic effect can also be enhanced by forming an antioxidant film on the surface of the molten zinc by flowing any one of the mixed gas with the above.

As described above, according to the method of the present invention, even when the temperature is raised to 850 ° C., the contact between the molten zinc and the air is cut off and the combustion of zinc can be prevented. Melting of zinc master alloy is possible.

[0023]

Embodiments of the present invention will be described below.

Example 1 After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a No. 10 graphite crucible, the temperature of the molten metal was maintained at 650 ° C., and 390 gr of spherical nickel was added therein, and the graphite was added. 2 liters of carbon dioxide in the crucible
The temperature was raised to 750 ° C. at a flow rate of / min, and the mixture was maintained for 30 minutes with occasional stirring. Nickel had not melted yet. Then, gradually raise the temperature to 800 ° C.
Was completely dissolved. Further, 390 gr of spherical Ni is added and 30
After stirring for 750 minutes, the temperature was raised to 850 ° C. and maintained for 30 minutes.
The temperature was lowered to 0 ° C. Nickel dissolved completely. After that, it was cast into an ingot case. When nickel in the mother alloy was analyzed, it was 9.8% by weight.

Example 2 After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a No. 10 graphite crucible, the temperature of the molten metal was maintained at 650 ° C., and 390 gr of spherical nickel was added therein. 2 l / m of air containing sulfur hexafluoride (1% sulfur hexafluoride + 99% air) in a graphite crucible
The temperature was raised to 750 ° C. while flowing in, and the mixture was maintained for 30 minutes with occasional stirring. Nickel had not melted yet.
Thereafter, the temperature was gradually raised to 800 ° C. with stirring and maintained for 30 minutes to completely dissolve Ni. Further, 390 gr of spherical Ni was added and stirred for 30 minutes. Thereafter, the temperature was raised to 850 ° C.
After holding for 0 minutes, the temperature was lowered to 750 ° C., followed by stirring. Nickel dissolved completely. After that, it was cast into an ingot case. When nickel in the mother alloy was analyzed, it was 9.9% by weight.

Example 3 After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a graphite crucible No. 10, the temperature of the molten metal was maintained at 650 ° C., and 390 gr of spherical nickel was added therein. The temperature was raised to 750 ° C. while flowing carbon dioxide gas at 1 liter / min and 1% sulfur hexafluoride / air at 1 liter / min in the graphite crucible, and the mixture was stirred and held for 30 minutes. Nickel had not melted yet. Thereafter, the temperature was gradually raised to 800 ° C. with stirring and maintained for 30 minutes.
Was completely dissolved. Further, 390 gr of spherical Ni is added and 30
Stirred for minutes. Thereafter, the temperature was raised to 850 ° C. and maintained for 30 minutes, and then the temperature was lowered to 750 ° C. and stirred. Nickel dissolved completely. After that, it was cast into an ingot case. Analysis of nickel in the mother alloy was 10.0% by weight.

Example 4 7 kg of distilled zinc ingot (one kind) according to JIS H2107 was melted in a graphite crucible No. 10, the temperature of the molten metal was maintained at 700 ° C., and 780 gr of spherical nickel was added thereto. The temperature was gradually raised to 820 ° C. while covering the surface of the molten metal with 200 gr of coke powder, held for about 30 minutes, and 100 gr of coke powder was added. Then, the temperature was raised to 850 ° C. and held for 30 minutes. Thereafter, the temperature was lowered to 800 ° C., followed by stirring. Nickel was completely dissolved. Thereafter, except for the coke floating on the surface, it was cast into an ingot case.
Analysis of nickel in the mother alloy was 10.1% by weight.

Example 5 After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a No. 10 graphite crucible, the temperature of the molten metal was maintained at 700 ° C., and 780 gr of spherical nickel was added thereto. The surface of the molten metal was covered with 200 gr of carbon powder, and the temperature was gradually raised to 820 ° C. while flowing and stirring at 2 L / min of carbon dioxide gas, and held for about 30 minutes. After further adding 100 gr of carbon powder, the temperature was raised to 850 ° C. and maintained for 30 minutes. Thereafter, the temperature was lowered to 800 ° C., followed by stirring. Nickel was completely dissolved. After that, the carbon powder floating on the surface was cast into an ingot case. Analysis of nickel in the mother alloy was 10.0% by weight. In this embodiment, the effect of suppressing combustion was observed by using carbon dioxide gas in combination as compared with the fourth embodiment.

Example 6 After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a No. 10 graphite crucible, the temperature of the molten metal was maintained at 700 ° C., and 780 gr of spherical nickel and 200 gr of carbon powder were contained therein. The mixture was further injected with 1% sulfur hexafluoride / 99% air at a flow rate of 1 liter / min, stirred, gradually heated to 820 ° C., and held for about 30 minutes. After further adding 100 gr of carbon powder, the temperature was raised to 850 ° C. and maintained for 30 minutes. Thereafter, the temperature was lowered to 800 ° C., followed by stirring. Nickel was completely dissolved. After that, the carbon powder floating on the surface was cast into an ingot case. Analysis of nickel in the master alloy revealed 9.9% by weight
Met.

Comparative Example After melting 7 kg of distilled zinc ingot (one kind) in accordance with JIS H2107 in a No. 10 graphite crucible, the temperature of the molten metal was maintained at 650 ° C. which does not cause combustion, and 390 gr of spherical nickel was contained therein. Was added. Thereafter, the temperature was raised to 700 ° C. in a graphite crucible and stirred. During this stirring, the zinc had evaporated considerably. Thereafter, the zinc was evaporated at 770 ° C. while the temperature of the molten metal was being raised, and the molten metal could not be melted and burned. Nickel hardly dissolved and remained at the bottom.

[0031]

As described above, according to the present invention, according to the present invention, the surface of the molten metal is covered with carbon dioxide to avoid contact with the air, and the surface of the molten metal is covered with a carbide such as coke, charcoal or carbon. Avoid contact between oxygen and molten metal,
An antioxidant film is formed on the surface of the molten zinc with any of sulfur hexafluoride, air containing sulfur hexafluoride, or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas, to form carbides such as coke, charcoal, and carbon. Combined with carbon dioxide gas to cover the surface of the zinc melt and avoid contact with oxygen in the air,
Simultaneously or after covering the zinc melt surface with carbides such as carbon, by flowing either sulfur hexafluoride, air containing sulfur hexafluoride or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas Further, the evaporation and combustion of zinc in the atmosphere can be suppressed, and the nickel content in the hot-dip galvanizing bath can always be properly maintained. Among them, the method of forming an antioxidant film by the combined use of carbon and a gas containing sulfur hexafluoride and the method of covering the surface of the molten metal with carbon exhibit particularly excellent effects.

Further, it is possible to provide a high nickel-zinc master alloy for use as a nickel source of a nickel-containing zinc alloy, which can greatly contribute to a reduction in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a drawing showing a molten state of a zinc alloy containing 10% or less of nickel.

Claims (6)

[Claims] 1. The composition according to claim 1, which contains not more than 10% by weight of nickel.
8% by weight or less, iron of 0.1% by weight or less, cadmium of 0.5% by weight or less, nickel consisting of zinc and unavoidable impurities
A method for producing a nickel-zinc master alloy, the method comprising: covering the surface of a molten zinc metal with carbon dioxide gas and maintaining the temperature at 850 ° C. or less until the nickel is completely melted while cutting off the contact with air. Method. 2. The composition according to claim 1, which contains not more than 10% by weight of nickel and contains lead 1.
8% by weight or less, iron of 0.1% by weight or less, cadmium of 0.5% by weight or less, nickel consisting of zinc and unavoidable impurities
In the smelting of a zinc mother alloy, the surface of the molten zinc is covered with carbide such as coke, charcoal, carbon, etc., and kept at a temperature of 850 ° C or less until the nickel is completely melted while cutting off the contact between the molten zinc and oxygen in the air. A method for producing a nickel-zinc master alloy. 3. The composition according to claim 1, which contains not more than 10% by weight of nickel and contains lead 1.
8% by weight or less, iron of 0.1% by weight or less, cadmium of 0.5% by weight or less, nickel consisting of zinc and unavoidable impurities
In the smelting of a zinc master alloy, either one of sulfur hexafluoride, air containing sulfur hexafluoride, or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas flows, and an antioxidant film is formed on the surface of the zinc melt. And producing the nickel-zinc master alloy at a temperature of 850 ° C. or lower until nickel is completely dissolved. 4. The nickel-zinc master alloy according to claim 2, wherein the surface of the molten zinc is covered by using carbon dioxide in combination with the coke, charcoal, carbon or the like.
Manufacturing method of zinc master alloy. 5. The method for producing a nickel-zinc master alloy according to claim 2, wherein the surface of the molten zinc is covered with a carbide such as coke, charcoal, carbon or the like to cut off contact with air, or thereafter, after the sulfur hexafluoride, A nickel-zinc mother alloy characterized in that an antioxidant film is formed on the surface of a molten zinc by flowing either air containing sulfur fluoride or a mixed gas of air containing sulfur hexafluoride and carbon dioxide gas. Manufacturing method. 6. A nickel-zinc master alloy produced by the method according to claim 1. Description: