JP2009174902A - Analyzing method of very small amount of element in alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an analyzing method of a very small amount of an element in an alloy capable of analyzing a very small amount of the element contained in the alloy much in the content of silicon with high precision. <P>SOLUTION: The analyzing method of a very small amount of the element in the alloy is constituted so as to analyze a very small amount of the element in the alloy which contains a first metal larger than hydrogen in ionization tendency as a main component and also contains a very small amount of the element and silicon that is 0.5 mass% or above per 100 mass% of the whole of the alloy and provided with the acid treatment process for heating the alloy along with an acid treatment liquid to dissolve the first metal, and a hydrofluoric acid treatment process for adding hydrofluoric acid to the treatment liquid after the acid treatment process to dissolve silicon and a very small amount of the element. Alternatively, the acid-hydrofluoric acid treatment process is provided for heating the alloy along with the acid treatment liquid and hydrofluoric acid to dissolve not only the first metal by the acid treatment liquid but also silicon by hydrofluoric acid. By eliminating the filtering process, a very small amount of the element can be analyzed with high precision. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for analyzing trace elements in an alloy containing silicon.

  An alloy such as an aluminum-silicon alloy contains a trace element. Trace elements are generally added to these alloys for the purpose of refining crystal grains and improving the strength of the alloys. For example, JIS H 1306 defines a method for analyzing iron, copper, manganese, zinc, magnesium, chromium, nickel, bismuth, and lead contained in an aluminum alloy. In this method, atomic absorption analysis is performed by dissolving aluminum with hydrochloric acid and hydrogen peroxide to elute trace elements contained in the aluminum alloy. If there is any insoluble matter after dissolution with hydrochloric acid and hydrogen peroxide, filter with filter paper, ash the insoluble matter (filter residue) and filter paper, and dissolve the residual components after ashing with nitric acid and hydrofluoric acid. To do. Thereafter, the dissolved solution and the filtrate are subjected to atomic absorption analysis. A method for analyzing trace elements contained in an aluminum alloy is also defined in the Light Metal Association Standard (LIS A03). This method is also the same as JIS H 1306.

By the way, when analyzing a trace element contained in an aluminum-silicon alloy having a large silicon content (for example, silicon containing 0.5% by mass or more in 100% by mass of the whole alloy) by this method. There was a problem that trace elements could not be analyzed with high accuracy.
JIS H 1306

  This invention is made | formed in view of the said situation, and it aims at providing the analysis method of the trace element in the alloy which can analyze the trace element contained in an alloy with many silicon contents with high precision.

  A method for analyzing a trace element in an alloy of the present invention that solves the above problem is an alloy containing a first metal having a higher ionization tendency than hydrogen as a main component, a trace element and silicon, and a mass of the entire alloy of 100. A method for analyzing trace elements in an alloy containing 0.5% by mass or more of silicon in mass%, wherein the alloy is heated with an acid treatment solution to dissolve the first metal, Hydrofluoric acid treatment step in which hydrofluoric acid is added to the treatment solution after the acid treatment step to dissolve silicon and trace elements, and the treatment solution after the hydrofluoric acid treatment step is heated to obtain hydrofluoric acid The sample is prepared from the volatilization process that volatilizes, the salt dissolution process that dissolves the salt in the residual component by adding acid to the residual component after the volatilization process, the pretreatment process that includes the residual component after the pretreatment process Analysis process for analyzing trace elements in analysis samples , Characterized in that it comprises a.

  In addition, the method for analyzing trace elements in an alloy of the present invention that solves the above problems is an alloy containing a first metal having a higher ionization tendency than hydrogen as a main component and containing trace elements and silicon. A method for analyzing trace elements in an alloy containing silicon in an amount of 0.5% by mass or more in 100% by mass, wherein the alloy is heated together with an acid treatment liquid and hydrofluoric acid, An acid / hydrofluoric acid treatment step of dissolving the first metal and dissolving silicon and trace elements with hydrofluoric acid, and heating the treatment liquid after the acid / hydrofluoric acid treatment step to fluorinate Analysis sample from volatilization process for volatilizing hydrogen acid, salt dissolution process for adding salt to residual component after volatilization process to dissolve salt in residual component, pretreatment process including residual component after pretreatment process Prepare a trace amount of analysis sample Characterized in that it comprises an analysis step of analyzing the element, the.

  The method for analyzing trace elements in the alloy of the present invention preferably comprises any of the following (1) to (4). More preferably, a plurality of (1) to (4) are provided.

  (1) The first metal is at least one of aluminum and iron.

  (2) The acid treatment liquid is one type selected from hydrochloric acid, nitric acid, sulfuric acid, a mixed liquid of hydrochloric acid and nitric acid, and a mixed liquid of hydrochloric acid and hydrogen peroxide.

  (3) The acid treatment liquid is a mixed liquid of an acid having an oxidizing power for a metal having a smaller ionization tendency than hydrogen and an acid having an oxidizing power for a metal having a smaller ionization tendency than hydrogen.

  (4) The trace element is at least one selected from sodium, calcium, phosphorus, strontium, niobium, and titanium.

  As a result of intensive studies, the inventors of the present invention have found that the reason why a trace element contained in an alloy having a high silicon content cannot be analyzed with high accuracy by the analysis method defined in JIS H 1306 or LIS A03 is in the filtration process. Elucidated. For example, aluminum in an aluminum-silicon alloy dissolves in hydrochloric acid and hydrogen peroxide, but silicon is insoluble in hydrochloric acid and hydrogen peroxide. For this reason, when an alloy with a high silicon content is dissolved with hydrochloric acid and hydrogen peroxide, a large amount of insoluble matter is generated, and a filtration step becomes essential. Since a general filter paper contains a very small amount of impurities (for example, calcium, sodium, etc.), the analysis sample is contaminated by the filter paper impurities. For this reason, when analyzing an analysis sample, the whole signal intensity becomes high, and it becomes impossible to analyze a trace element with high accuracy.

  According to the method for analyzing trace elements in an alloy of the present invention, the first metal (for example, aluminum) in the alloy is dissolved by the acid treatment solution, and then hydrofluoric acid is added to the treatment solution after the acid treatment step. To dissolve the silicon. Alternatively, the first metal in the alloy is dissolved by the acid treatment liquid and silicon is dissolved by hydrofluoric acid. Therefore, silicon in the alloy can be dissolved while omitting the filtration step, and all or almost all trace elements can be dissolved while preventing the analysis sample from being contaminated by the filter paper. Therefore, according to the analysis method of trace elements in the alloy of the present invention, trace elements can be analyzed with high accuracy.

  According to the method for analyzing trace elements in an alloy of the present invention, trace elements in an alloy containing at least one of aluminum and iron as the first metal can be analyzed particularly accurately. Further, according to the method for analyzing trace elements in an alloy of the present invention, a trace element composed of at least one selected from sodium, calcium, phosphorus, strontium, niobium, and titanium in the alloy can be analyzed particularly accurately.

  In the method for analyzing trace elements in the alloy of the present invention, one kind selected from hydrochloric acid, sulfuric acid, nitric acid, a mixed liquid of hydrochloric acid and nitric acid, and a mixed liquid of hydrochloric acid and hydrogen peroxide is used as the acid treatment liquid. In this case, the trace element in the alloy can be dissolved with high reliability, and the trace element in the alloy can be analyzed with higher accuracy.

  In the method for analyzing trace elements in an alloy of the present invention, as an acid treatment solution, a mixture of an acid having an oxidizing power for a metal having a lower ionization tendency than hydrogen and an acid having no oxidizing power for a metal having a lower ionization tendency than hydrogen. In the case of using a liquid, the first metal is dissolved by an acid that does not oxidize a metal that has a lower ionization tendency than hydrogen, and is included in the alloy by an acid that has an oxidative power for a metal that has a lower ionization tendency than hydrogen. Metals other than the first metal can be dissolved. For this reason, in this case, the trace element in the alloy can be dissolved with high reliability, and the trace element in the alloy can be analyzed with higher accuracy.

  The trace element analysis method in the alloy of the present invention (hereinafter simply referred to as the analysis method of the present invention) analyzes trace elements in an alloy mainly composed of a first metal having a higher ionization tendency than hydrogen. Is the method. Examples of the first metal having a higher ionization tendency than hydrogen include aluminum and iron. Therefore, the analysis method of the present invention is preferably used as a method for analyzing trace elements contained in an aluminum-silicon alloy or cast iron.

  The alloy to be analyzed by the analysis method of the present invention is preferably one in which 70% by mass to 95% by mass of the first metal is contained in 100% by mass of the total mass of the alloy. Moreover, it is good that 0.5 mass%-20 mass% of silicon is contained in 100 mass% of the whole alloy. According to the analysis method of the present invention, trace elements in these alloys can be analyzed with high accuracy.

  In the analysis method of the present invention, the hydrofluoric acid treatment step may be performed after the acid treatment step or may be performed simultaneously with the acid treatment step (that is, the acid / hydrofluoric acid treatment step). In any case, the trace element in the alloy can be dissolved with high reliability by dissolving the first metal with the acid treatment liquid and dissolving the silicon with hydrofluoric acid. Can be analyzed with high accuracy. In the case where the hydrofluoric acid treatment step and the acid treatment step are performed simultaneously (acid / hydrofluoric acid treatment step), the reaction system is compared with the case where the hydrofluoric acid treatment step is performed after the acid treatment step. What is necessary is just to make the hydrofluoric acid density | concentration inside high.

  As the acid treatment solution in the analysis method of the present invention, a solution capable of dissolving the first metal may be used. Examples of the acid treatment liquid that can dissolve the first metal include hydrochloric acid, sulfuric acid, nitric acid, a mixed liquid of hydrochloric acid and nitric acid, a mixed liquid of hydrochloric acid and hydrogen peroxide, and the like. Of these, hydrochloric acid and sulfuric acid are acids that have less oxidizing power than metals that are less ionizable than hydrogen (that is, acids that do not have oxidizing power), but dissolve metals that have a higher ionization tendency than hydrogen. For this reason, these acids can dissolve the first metal. Further, when the alloy contains a metal (eg, copper) having a smaller ionization tendency than hydrogen in addition to the first metal, an acid and hydrogen having an oxidizing power for a metal having a smaller ionization tendency than hydrogen as the acid treatment liquid. What is necessary is just to use the liquid mixture with the acid without the oxidizing power with respect to the metal with a smaller ionization tendency than. Examples of this type of mixed solution include a mixed solution of hydrochloric acid and nitric acid (including aqua regia), a mixed solution of hydrochloric acid and hydrogen peroxide, and the like.

  For reference, Table 1 shows the solubility of cast iron and aluminum-silicon alloy in the various acid treatment solutions described above. As hydrochloric acid, concentrated hydrochloric acid and water mixed at a volume ratio of 1: 1 were used. Nitric acid used was a mixture of concentrated nitric acid and water at a volume ratio of 1: 1. As sulfuric acid, concentrated sulfuric acid and water mixed at a volume ratio of 1: 9 were used. As aqua regia, aqua regia (concentrated hydrochloric acid and concentrated nitric acid mixed at a volume ratio of 3: 1) and water mixed at a volume ratio of 1: 1 was used. As a mixed solution of hydrochloric acid and nitric acid, a mixture of concentrated hydrochloric acid and water in a volume ratio of 1: 1 and a mixture of concentrated nitric acid in a volume ratio of 1: 1 were used. As a mixed solution of hydrochloric acid and hydrogen peroxide, a mixture of concentrated hydrochloric acid and water in a volume ratio of 1: 1 and a mixture of hydrogen peroxide water in a volume ratio of 1: 1 were used. Moreover, the operation | work which melt | dissolves each alloy with each acid treatment liquid was performed, heating an acid treatment liquid and an alloy with a heater. The heater temperature at this time was about 400 ° C.

  As shown in Table 1, each acid treatment solution sufficiently dissolves iron (first metal) and other metals in cast iron, and aluminum (first metal) and other metals in an aluminum-silicon alloy. Thoroughly dissolve the metal. When hydrofluoric acid was added to a treatment solution obtained by dissolving each alloy with each acid treatment solution, silicon was dissolved, and trace elements such as niobium, titanium, calcium, phosphorus, and strontium were dissolved. From this result, hydrochloric acid, sulfuric acid, nitric acid, a mixed liquid of hydrochloric acid and nitric acid (including aqua regia), and a mixed liquid of hydrochloric acid and hydrogen peroxide are preferably used as an acid treatment liquid capable of dissolving the first metal. I understand that

  As a method for analyzing trace elements in the analysis step of the analysis method of the present invention, a general elemental analysis method such as atomic absorption analysis or ICP (Inductively Coupled Plasma) mass spectrometry may be used. As described above, since the pretreatment process in the analysis method of the present invention does not include the process of filtering with filter paper, trace elements can be analyzed with high accuracy by these analysis methods.

  Hereinafter, a method for analyzing trace elements in the alloy of the present invention will be described with specific examples.

(Example)
In the analysis methods of the examples, four types of aluminum-silicon alloys (BRAMMER certified standard substance V3204-2, BRAMMER certified standard substance V3200-2, BRAMMER certified standard substance V3046-3, BRAMMER certified standard substance AL413 are used as the alloys. / 03) was used. Each aluminum-silicon alloy contains about 12% silicon by weight with respect to 100% by weight of the total alloy. Each aluminum-silicon alloy contains about 85% by mass of aluminum with respect to 100% by mass of the entire alloy. Furthermore, among these, V3204-2 contains 23 ppm of calcium. V3200-2 contains 28 ppm of calcium. V3046-3 contains 13 ppm phosphorus. AL413 / 03 contains 11 ppm phosphorus.

  Hereinafter, the analysis method of an Example is demonstrated in detail.

(Pretreatment process 1. Acid treatment process)
First, 1 g of each aluminum-silicon alloy cutting piece was taken in a beaker made of fluororesin. To this beaker, 40 ml of an acid treatment solution obtained by mixing concentrated hydrochloric acid and water at a volume ratio of 1: 1 was added, and 10 ml of concentrated nitric acid was gradually added.

  This treatment liquid was heated to 400 to 500 ° C. with a heater. In this step, the aluminum in the alloy was dissolved.

(Pretreatment process 2. Hydrofluoric acid treatment process)
The treatment liquid after the acid treatment step was removed from the heater, and 1 to 10 ml of hydrofluoric acid was added to the treatment liquid. In this step, silicon and trace elements in the alloy (in the treatment liquid) were dissolved.

(Pretreatment process 3. Volatilization process)
The treatment liquid after the hydrofluoric acid treatment step was again applied to a heater, heated to 200 ° C., and dried. In this step, hydrofluoric acid was volatilized.

(Pretreatment process 4. Salt dissolution process)
The remaining components after the volatilization step were allowed to cool. Thereafter, 20 ml of an acid solution obtained by mixing concentrated hydrochloric acid and water at a volume ratio of 1: 1 was added to the remaining components, and heated at 200 ° C. until the remaining components were dissolved. In this step, the salt in the residual components was dissolved.

(Analysis process)
The treatment solution after the salt dissolution step was allowed to cool and the volume was adjusted to 100 ml to prepare an analytical sample. Trace elements (calcium, phosphorus) in this analysis sample were analyzed (quantified) by ICP. As an ICP device, ICPV8100 manufactured by Shimadzu Corporation was used. The high-frequency output during analysis was 1.2 kW. The plasma observation height was 15 mm. The amounts of argon gas were plasma: 14 L / min, coolant: 1.5 L / min, and carrier: 0.7 L / min. The analysis wavelengths were calcium: 393.7 nm and phosphorus: 178.29 nm. The analysis step was performed five times for each aluminum-silicon alloy analysis sample. The analysis results obtained in the analysis step are shown in Tables 2 to 5 described later.

(Comparative example)
In the analysis method of the comparative example, the same four types of alloys as the analysis method of the example were used as the alloys. The analysis method of the comparative example is a method based on the Light Metal Association analysis method (LIS A03).

  Hereinafter, the analysis method of the comparative example will be described in detail.

(Pretreatment process 1. Acid treatment process)
First, 1 g of each aluminum-silicon alloy cutting piece was taken in a beaker made of fluororesin. To this beaker, 50 ml of an acid treatment solution obtained by mixing concentrated hydrochloric acid and water at a volume ratio of 1: 1 was added. This treatment liquid was heated to 400 to 500 ° C. with a heater.

(Pretreatment process 2. Hydrofluoric acid treatment process)
The treatment liquid was removed from the heater, allowed to cool, then filtered through a filter paper (5B), and separated into a filtrate and an insoluble matter (filter residue). The insoluble matter and filter paper were incinerated, and the residual components after incineration were dissolved with hydrofluoric acid.

(Pretreatment process 3. Volatilization process)
The treatment liquid after the hydrofluoric acid treatment step was taken in a platinum instrument, heated to 400 to 500 ° C., and dried to evaporate hydrofluoric acid. In addition, the heating temperature in the volatilization process of a comparative example and the salt dissolution process mentioned later is higher than the heating temperature in the volatilization process and salt dissolution process of an Example. This is because the processing liquid is not in the fluororesin beaker but in the platinum instrument.

(Pretreatment process 4. Salt dissolution process)
An acid solution obtained by mixing concentrated hydrochloric acid and water at a volume ratio of 1: 1 was added to the residual component after the volatilization step, and heated at 400 to 500 ° C. until the residual component was dissolved.

(Analysis process)
The treatment liquid after the salt dissolution step and the filtrate were combined and the volume was adjusted to 200 ml to prepare an analytical sample. Trace elements (calcium, phosphorus) in this analysis sample were analyzed (quantified) by ICP in the same manner as in the analysis step of the example. Tables 2 to 5 show the analysis results obtained in the analysis step.

  As shown in Tables 2 to 5, according to the analysis method of the example, an analysis value close to the standard value was obtained as compared with the analysis method of the comparative example. Moreover, there was little dispersion | variation in the analysis value by the analysis method of an Example. From this result, it can be seen that the trace element in the alloy can be analyzed with high accuracy according to the analysis method of the example (that is, the trace element analysis method in the alloy of the present invention).

Claims (6)

An alloy containing, as a main component, a first metal that has a higher ionization tendency than hydrogen and containing a trace element and silicon, the silicon is contained in an amount of 0.5% by mass or more in 100% by mass of the entire alloy. A method for analyzing trace elements in an alloy,
An acid treatment step of heating the alloy together with an acid treatment solution to dissolve the first metal;
Hydrofluoric acid treatment step of adding hydrofluoric acid to the treatment liquid after the acid treatment step to dissolve the silicon and the trace elements;
A volatilizing step of heating the treatment liquid after the hydrofluoric acid treatment step to volatilize the hydrofluoric acid;
A salt dissolution step of adding an acid to the residual component after the volatilization step to dissolve the salt in the residual component;
A pretreatment process including:
An analysis step of preparing an analysis sample from the residual components after the pretreatment step and analyzing the trace element of the analysis sample, and a method for analyzing the trace element in the alloy. An alloy containing, as a main component, a first metal that has a higher ionization tendency than hydrogen and containing a trace element and silicon, the silicon is contained in an amount of 0.5% by mass or more in 100% by mass of the entire alloy. A method for analyzing trace elements in an alloy,
The alloy is heated with an acid treatment solution and hydrofluoric acid to dissolve the first metal with the acid treatment solution and to dissolve the silicon and the trace element with the hydrofluoric acid. Hydroacid treatment process;
A volatilization step of heating the treatment liquid after the acid / hydrofluoric acid treatment step to volatilize the hydrofluoric acid;
A salt dissolution step of adding an acid to the residual component after the volatilization step to dissolve the salt in the residual component;
A pretreatment process including:
An analysis step of preparing an analysis sample from the residual components after the pretreatment step and analyzing the trace element of the analysis sample, and a method for analyzing the trace element in the alloy.   The method for analyzing trace elements in an alloy according to claim 1 or 2, wherein the first metal is at least one of aluminum and iron.   The acid treatment solution is one selected from hydrochloric acid, sulfuric acid, nitric acid, a mixed solution of hydrochloric acid and nitric acid, and a mixed solution of hydrochloric acid and hydrogen peroxide solution. Of trace elements in alloys.   The acid treatment solution is a mixed solution of an acid having an oxidizing power for a metal having a smaller ionization tendency than hydrogen and an acid having an oxidizing power for a metal having a smaller ionization tendency than hydrogen. The analysis method of the trace element in the alloy as described in any one.   The method for analyzing a trace element in an alloy according to any one of claims 1 to 5, wherein the trace element is at least one selected from sodium, calcium, phosphorus, strontium, niobium, and titanium.