JP2011202233A - TRACE ELEMENT-ADDED Ag ALLOY AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problems: in Ag dissolved by addition of a deoxidizer thereto, the deoxidizer remains in the Ag, however sometimes the remaining of the deoxidizer can not be allowed upon the production of Ag alloy admixed with a trace amount of element for alloying, and further, Ag has the characteristics of occluding oxygen upon dissolution, and when an element for alloying is added to Ag, the reaction of the element with oxygen to be absorbed into the Ag must be sufficiently considered.SOLUTION: The trace element-added Ag alloy is characterized in that Ag with ≥99.99 wt.% purity in which the content of oxygen is controlled to <10 ppm is blended with one or more kinds selected from among Al, Mg, Si, Zn, Bi, Ge and Pd in an amount of 0.005 to 0.1 wt.% as an additional element.

Description

  The present invention relates to a trace element-added Ag alloy that can be used for optical recording disks, solar cell targets, and the like that require high reflectivity and heat resistance, and a method for producing the same.

  For example, since Ag targets are excellent in light reflectance, pure Ag is mainly used.

  However, since pure Ag is sulfided in the atmosphere, there is a problem in its corrosion resistance.

  The Ag target is dissolved by gas melting, high-frequency melting or the like, and is rolled and cut to finish to a specified dimension.

  However, molten Ag easily absorbs oxygen due to its characteristics, and releases oxygen when solidified, but there is a problem that even if it becomes an ingot, oxygen remains in the Ag structure.

  For this reason, generally, as a measure for preventing oxygen storage, a small amount of a deoxidizer is added and dissolved (see, for example, Patent Document 1).

JP-A-7-258830

  The inventor of the present application paid attention to a trace element-added Ag alloy in a state very close to pure Ag in order to have high reflectivity and thermal conductivity and to improve durability.

  In Ag dissolved by adding a deoxidizing agent, the deoxidizing agent remains in the Ag. However, when producing an Ag alloy to which a small amount of an element for the alloy is added, the deoxidizing agent in the Ag is used. It is desirable not to use a deoxidizer because the residual may not be acceptable.

  Further, as described above, Ag has a characteristic of storing oxygen when dissolved, and when an alloying element is added, a reaction with oxygen stored in Ag must be considered. In particular, if the element to be added is an element that easily binds to oxygen, the added element is oxidized and becomes an oxide at the time of dissolution, so that the oxide is released from the molten metal and floats. The composition of the Ag alloy cannot be stabilized according to the composition.

Furthermore, even if the atmosphere during the dissolution of Ag is in a state where oxygen is not present, that is, an atmosphere of an inert gas such as Ar or N ₂ is used to block oxygen, an Ag ingot that has already occluded oxygen is used. Less effective. When the atmosphere is in a vacuum state, the boiling point of Ag is lowered and a vaporization phenomenon occurs, so that it is difficult to obtain a stable composition.

  An object of the present invention is to solve such a problem.

Therefore, the present invention is to heat Ag at a purity of 99.99 wt% or more in an inert gas such as Ar or N ₂ at 400 ° C. to 700 ° C. for 1 hour or more to reduce the oxygen content to less than 10 ppm. By mixing one or more of Al, Mg, Si, Zn, Bi, Ge, and Pd as a trace additive element and mixing 0.005 wt% to 0.1 wt%, the desired blending value can be obtained. An Ag alloy having a composition can be obtained.

At the time of blending the trace additive element, the trace additive element is put into an Ag pipe made using Ag with an oxygen content of less than 10 ppm and having a purity of 99.99 wt% or more, and the inside of the Ag pipe is evacuated or inactive. Sealing is performed after filling with the gas, and dissolution is performed in a state where the atmosphere during dissolution of the Ag alloy is replaced with an inert gas such as Ar or N ₂ to suppress oxidation. If necessary, the same Ag ingot as that of the Ag pipe is weighed and dissolved as required for adjusting the blending value.

  Here, the reason for setting the oxygen content of Ag for blending to 10 ppm is that, when the oxygen content of Ag is 10 ppm or more, the blended value of This is because there is a difference between the composition and the composition after dissolution.

  The reason why the additive element addition amount is 0.005 wt% to 0.1 wt% is that if the lower limit is less than 0.005 wt%, the corrosion resistance cannot be improved, and the upper limit is more than 0.1 wt%. This is because the high reflectivity and thermal conductivity inherent in Ag cannot be obtained.

  The reason why the trace additive element is put in the Ag pipe and the inside of the pipe is filled with a vacuum or an inert gas is that the trace additive element is prevented from reacting with oxygen in the air when dissolved, This is to prevent oxidation and liberation from the molten metal. Furthermore, the reason for substituting the atmosphere at the time of dissolution with an inert gas is to suppress the reaction with oxygen in the air.

  According to the present invention as described above, the reaction with oxygen as much as possible at the time of dissolution of the Ag alloy is performed using Ag with an oxygen content of less than 10 ppm by heating at 400 ° C. to 700 ° C. for 1 hour or more in an inert gas. By suppressing the above, it becomes possible to produce an Ag alloy having a composition with a desired blending value. As a result, for example, a durable Ag alloy that can be used for an optical recording disk or a solar cell target that is required to have a high reflectance and a uniform reflectance can be produced.

Explanatory drawing of the sample collection for the analysis of Ag alloy using the high frequency continuous casting machine of Example 1. FIG. Explanatory drawing of the sampling collection for the analysis of Ag alloy using the high frequency continuous casting machine of Example 2. FIG. Explanatory drawing of the sample collection for the analysis of Ag alloy using the high frequency melting furnace of a prior art example. Explanatory drawing of the sample collection for the analysis of Ag alloy using the high frequency continuous casting machine of a prior art example.

  Examples of the present invention will be described below.

  The target composition of this example is set to Ag 99.995 wt% to 99.90 wt%, and trace added elements 0.005 wt% to 0.1 wt%.

  In this example, a pipe and an ingot having an oxygen content of less than 10 ppm and a purity of 99.99 wt% are used as the mixing Ag.

First, Ag having a purity of 99.99 wt% or more weighed to a predetermined amount so as to have a target composition is maintained at 700 ° C. for 1 hour in an N ₂ atmosphere as an inert gas atmosphere to make the oxygen content less than 10 ppm. .

  Ag pipes and Ag ingots are produced using Ag with an oxygen content of less than 10 ppm.

  Next, a small amount of additive element weighed to a predetermined amount so as to have a target composition is put into the Ag pipe, vacuumed, sealed, and prevented from contacting with oxygen.

  Thereafter, the above-mentioned sealed Ag pipe material and the above-mentioned Ag ingot weighed for adjusting the blending value as necessary are put into a carbon crucible, and the crucible is put into a melting furnace of a high-frequency continuous casting machine. The furnace lid should be closed and opening of the furnace lid is strictly prohibited.

Therefore, the atmosphere is sufficiently replaced with N ₂ as an inert gas, and Ag and a trace amount of additive element are melted by high frequency induction heating. After melting, N ₂ gas is put into the molten metal and stirred. After stirring, after reaching the set temperature, pull it out with the specified die.

  Thereafter, as shown in FIG. 1, sampling was performed at 1, 2, and 3 locations, and quantitative analysis of Ag and trace added elements was performed. Table 1 shows the results of analysis using an ICP analyzer. In addition, evaluation is evaluation of whether an analysis value is in said target composition value range.

  A production example of an Ag alloy produced by the above-described process and using an additive element Mg will be described using numerical values.

  A production example of a 60 kg trace additive element Ag alloy will be described.

An Ag ingot having a purity of 99.99 wt% or more weighed to 59,997 g is maintained as an inert gas at 700 ° C. for 1 hour in an N ₂ atmosphere, so that the oxygen content is less than 10 ppm.

  Next, Mg as an additive element is weighed to 3.0 g so as to have a composition of 0.005 wt%.

  Next, a pipe was produced using 300 g of the Ag ingot having an oxygen content of less than 10 ppm. Specifically, the Ag ingot was rolled into a plate shape, bent into a cylindrical shape, and a pipe having an outer diameter φ43 mm, an inner diameter φ40 mm, and a length L150 mm was formed using a draw bench.

  After producing the pipe, the pipe was washed with an organic solvent acetone. After cleaning, the mouth on one side of the pipe is sealed by ordinary temperature welding, and Mg weighed to 3.0 g is added as an additive element into the pipe. At this time, the size (particle size) of the additive element is not specified, and may be any size that can fit in the pipe.

  Thereafter, the inside of the pipe is evacuated, and the pipe opening is sealed by ordinary temperature welding to suppress contact with oxygen.

  The sealed Ag pipe and the remaining ingot are placed in a carbon crucible, and the crucible is placed in a high frequency melting furnace of a high frequency continuous casting machine.

Thereafter, the furnace lid is closed, and replacement with N ₂ gas, which is an inert gas, is performed to suppress contact with oxygen. The furnace lid should be closed and not open. N ₂ gas continues to be extracted until the trace element-added Ag alloy is completely extracted.

Five minutes after the start of replacement, the high frequency power supply is turned on to a set temperature of 1100 ° C. and melting is performed. After the material is completely melted and turned into hot water, the N ₂ gas injection port is placed in the hot water and stirred with N ₂ gas for 3 minutes.

After 3 minutes, the N ₂ gas outlet is taken out of the hot water and the surface of the hot water is calmed for 5 minutes. After calming down, after reaching a predetermined temperature, it is pulled out with a die.

  The other trace additive element Ag alloys shown in Table 1 were also produced by the same method as described above.

  The target composition of this example is set to Ag 99.999 wt% to 99.91 wt%, and trace added elements 0.001 wt% to 0.09 wt%.

  It is extremely difficult to produce an Ag alloy to which a desired trace amount of element is added.

  This example is a manufacturing method for producing a second-diluted addition of trace element-added Ag alloy using the Ag alloy manufactured in Example 1 (hereinafter referred to as a master alloy). A description will be given using Ag-0.005 wt% Mg as an example.

First, Ag pipe and Ag ingot are prepared by weighing Ag, which is held at 700 ° C. for 1 hour in an N ₂ atmosphere as an inert gas atmosphere, and having an oxygen content of less than 10 ppm, to a predetermined amount.

  Next, the mother alloy weighed in a predetermined amount so as to have a target composition is put into the Ag pipe, vacuumed, sealed, and deterred from contact with oxygen.

  Thereafter, the above-mentioned sealed Ag pipe material and the above-mentioned Ag ingot weighed to adjust the blending value as required are placed in a carbon crucible, and the crucible is placed in a melting furnace using a high-frequency continuous casting machine. The furnace lid should be closed and opening of the furnace lid is strictly prohibited.

Therefore, the atmosphere is sufficiently replaced with N ₂ gas as an inert gas, and the additive element is secondarily diluted by high frequency induction heating. After melting, N ₂ gas is put into the molten metal and stirred. After stirring, after reaching the set temperature, the Ag alloy is drawn out with a specified die.

  Thereafter, as shown in FIG. 2, sampling was performed at 4, 5, and 6 to quantitatively analyze Ag and trace added elements. Table 2 shows the results of analysis using an ICP analyzer. In addition, evaluation is evaluation of whether an analysis value is in said target composition value range.

Comparative Example An example of a production method using a conventional deoxidizer will be described as a comparative example.

  The target composition is Ag 99.920 wt% and Mg is 0.005 wt% as a trace additive element.

  The materials used are Ag having a purity of 99.99 wt% and an oxygen content of 10 ppm or more, and Mg having a purity of 99.9 wt%.

  Ag and Mg weighed to a predetermined amount so as to have a target composition are put into a carbon crucible of a high-frequency melting furnace, and the crucible is put into the melting furnace. At this time, silicon-based flux is added as a deoxidizer.

Next, it is sufficiently substituted with N ₂ , melted in a high-frequency melting furnace, the furnace lid is opened, the N ₂ atmosphere is opened, and stirring is performed with a carbon stirring rod.

  Thereafter, the atmosphere was replaced, and after melting at a predetermined temperature equal to or higher than the melting point, it was cast into a specified mold. Thereafter, sampling was performed at 7, 8, and 9 shown in FIG. 3, and quantitative analysis of Ag and Mg was performed. Table 3 shows the results of analysis using an ICP analyzer. In addition, evaluation is evaluation of whether an analysis value is in said target composition value range.

  Next, the case where a high frequency continuous casting machine is used with the material produced by the said comparative example is demonstrated.

  The target composition is Ag 99.920 wt% and Mg is 0.005 wt% as a trace additive element.

  The materials used are Ag having a purity of 99.99 wt% and an oxygen content of 10 ppm or more, and Mg having a purity of 99.9 wt%.

  A predetermined amount of Ag and Mg weighed so as to have a target composition is put into a carbon crucible for a high-frequency continuous casting machine.

Next, the gas is sufficiently replaced with N ₂ gas, melted by high frequency induction heating, the furnace lid is opened, the N ₂ atmosphere is opened, and stirring is performed with a carbon stirring rod.

  Thereafter, the atmosphere is replaced, and after reaching a predetermined temperature, it is pulled out by a designated die. Thereafter, sampling was performed at 10, 11, and 12 shown in FIG. 4, and quantitative analysis of Ag and Mg was performed. Table 4 shows the results of analysis using an ICP analyzer. In addition, evaluation is evaluation of whether an analysis value is in said target composition value range.

  1-6 sampling points

Claims (6)

  0.005 wt% to 0.1 wt% of one or more of Al, Mg, Si, Zn, Bi, Ge, and Pd as additive elements to Ag with an oxygen content of less than 10 ppm and a purity of 99.99 wt% or more A trace element-added Ag alloy characterized by being blended.   Ag having a purity of 99.99 wt% or more is heated in an inert gas at 400 ° C. to 700 ° C. to reduce the oxygen content to less than 10 ppm. To this Ag having a purity of 99.99 wt% or more, Al, Mg , Si, Zn, Bi, Ge, Pd is mixed with 0.005 wt% to 0.1 wt% and dissolved, and a trace element-added Ag alloy is produced.   Ag having a purity of 99.99 wt% or more is heated in an inert gas at 400 ° C. to 700 ° C. to reduce the oxygen content to less than 10 ppm, and pipes and ingots are produced from the Ag having a purity of 99.99 wt% or more. One or more of Al, Mg, Si, Zn, Bi, Ge, and Pd are added as additive elements in the Ag pipe in an amount of 0.005 wt% to 0.1 wt%, and the pipe is filled with vacuum or an inert gas. Then, the Ag pipe is sealed to prevent contact with oxygen, and then dissolved in a crucible together with the Ag ingot weighed to adjust the blending value as necessary. Manufacturing method.   The trace element-added Ag alloy produced in claim 2 or claim 3 is further added with Ag having a purity of 99.99 wt% or more with an oxygen content of less than 10 ppm, so that the added element is 0.001 wt% to 0.09 wt%. A trace element-added Ag alloy having a composition of   Ag having a purity of 99.99 wt% or more is heated at 400 ° C. to 700 ° C. in an inert gas to reduce the oxygen content to less than 10 ppm, and a pipe is produced from the Ag having a purity of 99.99 wt% or more. The trace element-added Ag alloy prepared in claim 2 or 3 is placed in the pipe, and the pipe is filled with a vacuum or an inert gas, and then the Ag pipe is sealed to prevent contact with oxygen. Then, the trace element addition Ag alloy manufacturing method characterized by melt | dissolving after that.   Ag having a purity of 99.99 wt% or more is heated in an inert gas at 400 ° C. to 700 ° C. to reduce the oxygen content to less than 10 ppm, and pipes and ingots are produced from the Ag having a purity of 99.99 wt% or more. The trace element-added Ag alloy prepared in claim 2 or claim 3 is placed in the Ag pipe, and the pipe is filled with a vacuum or an inert gas, and then the Ag pipe is sealed to make contact with oxygen. A method for producing a trace element-added Ag alloy, characterized by being dissolved in a crucible together with the above Ag ingot weighed to adjust the blending value.

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