JPH0561593B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for analyzing trace impurities in high-purity aluminum, and proposes an analytical method that can quantify trace impurities with high sensitivity by concentrating them. . <Prior Art> In recent years, highly purified materials have been attracting attention in the materials industry, and the use of aluminum materials as electronic materials and semiconductor materials is being expanded. In such cases, quantitative analysis of trace impurities is required for quality assurance, etc. Conventionally, the quantitative analysis method for trace impurities in high-purity aluminum has been published by Ishihara and Mukai, Journal
Of Metals, September issue. 944 pages (1965) (H.
Ishihara, K., Mukai: J. of Metals., Sep, 944
(1965), Prasad et al., Transactions of the Indian Institute of Metals, Vol. 32, No. 2, p. 113 (1980) (RN
Prasad, et al.Transactions of The Indian
Institute of Metals 32 [2] (1980)), Fujimoto,
Others: As introduced in Sumitomo Chemical Technical Report Special Issue, 53 (1981), etc., the focus was on activation analysis and spark source mass spectrometry. However, these methods have problems such as requiring the use of a nuclear reactor, a small number of elements that can be analyzed, low analytical accuracy, and lack of rapid analysis. On the other hand, in chemical analysis methods as well, there is contamination from the reagents used and the atmosphere, so the analytical accuracy is not at a similarly satisfactory level. <Problems to be Solved by the Invention> In view of the above-mentioned current situation, the present inventor has repeatedly researched methods for analyzing trace amounts of impurities in aluminum, and has completed the present invention. The present invention deals with trace impurities in high purity aluminum,
In particular, we propose an analytical method suitable for quantifying trace impurities on the order of several ppm to several 1/100 ppm. Furthermore, we propose an analysis method that focuses on preparing a concentrate of impurities to be measured by a distillation method and then subjecting it to an appropriate analysis method, particularly preferably plasma emission spectrometry (ICP) or flameless atomic absorption spectrometry. It is something to do. <Means for solving the problem> The method for analyzing trace impurities in high-purity aluminum according to the present invention involves reacting ethyl bromide with a high-purity aluminum material in the presence of a platinum group catalyst and bromine, and then
This method is characterized in that the produced liquid is distilled under reduced pressure to separate the organic aluminum compound by distillation, and the residue is used as a secondary sample for trace analysis. That is, ethyl bromide is reacted with a high-purity aluminum material as an analysis sample in the presence of a platinum group catalyst such as platinum, palladium, etc. and bromine, and aluminum is liquefied as an organic aluminum compound. In this case, the high purity aluminum as the analytical sample is 99.9
% purity or higher, but to accelerate the reaction it is preferable to form it into a plate or swarf form (thickness 0.3 mm or less). It is appropriate to carry out the purification as a pretreatment. The surface purification method is carried out, for example, by washing with hydrochloric acid, repeating washing with water and an organic solvent (methanol, ether, etc.), and then drying by heating. In this case, Al with a purity of 99.9% or more is hardly dissolved even when exposed to hydrochloric acid, so the dissolution loss can be ignored. The action of ethyl bromide (C ₂ H ₅ Br) on a high-purity aluminum material is preferably carried out in the presence of a platinum group catalyst, and further in the presence of bromine as a co-catalyst. In this case, aluminum as the analytical sample is
Depending on the predicted purity value, 2 to 5 g is used, but 9 to 9.9 parts by weight of ethyl bromide, which does not contain metal ions and has a purity of 98% or more, is added to 1 part by weight of aluminum, and 4 to 5 g is added to this. 10 parts by weight of platinum group catalyst and
0.01 to 0.05 parts by weight of bromine is allowed to coexist. During the reaction, the temperature is heated to 20 to 35°C at the beginning of the reaction. After the reaction starts, no particular heating is required due to the reaction heat. On the other hand, since unreacted ethyl bromide is diffused, a condenser is installed at the top of the reactor to collect it, and the reaction continues while the ethyl bromide is condensed and refluxed into the reactor, and solid aluminum disappears. After everything in the reactor has liquefied, the reaction is maintained for several more minutes, and then the reaction operation is stopped. In order to prevent moisture from entering from the opening end of the condenser, it is desirable to provide a dehumidifying section containing a moisture absorbent/desiccant at the opening end of the condenser. In this case, the platinum group catalyst forms a cell with the aluminum, promoting dissolution of the aluminum while promoting the reaction with ethyl bromide. Bromine also promotes oxidative dissolution of aluminum. As a result of the above, solid aluminum is converted into a liquid organoaluminum compound, and impurities in the solid aluminum also form an organometallic compound. Next, vacuum distillation is performed to remove the organoaluminum compound, which is a large component, from the product liquid. First, the reactor containing the product liquid is connected to a vacuum distillation apparatus, and the product liquid is removed under reduced pressure, for example, under a reduced pressure of 10 Torr or less, preferably 1 to 5 Torr, or after purging with dry nitrogen gas, the pressure is reduced to 5 Torr or less, and the product liquid is removed. 120-150
Excess ethyl bromide and organoaluminum compounds are distilled off while heating to .degree. C., and vacuum distillation is continued for 1 to 2 hours, and the distillation is stopped when the distillate stops distilling. This allows the impurities in the sample aluminum to be concentrated in the residue, making it possible to perform highly accurate analysis. In these series of treatments, the equipment used is preferably made of quartz in order to prevent contamination from equipment materials. The residue obtained above is thermally decomposed using, for example, a mixed solution of hydrochloric acid and nitric acid, and the liberated metal elements are then analyzed for the elements contained therein using an appropriate analytical means. Considering the analytical accuracy and speed that can be obtained, plasma emission spectrometry is preferred when simultaneous multi-element analysis is expected, and flameless atomic absorption spectrometry is preferred when analysis of each element is sufficient. , conventional solid-state emission spectrometry, spectrophotometry, etc. can also be applied. For example, the analysis results by the plasma emission spectrometry described above were as follows.

[Table] In addition, in the method according to the present invention, appropriate accuracy cannot be expected because silicon (si) and gallium (Ga), which have properties similar to those of aluminum, are distilled out along with the organic aluminum compound. Therefore, it cannot be applied to quantitative analysis of these elements. <Examples> Next, the method of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 Quantitative analysis was performed on standard samples commercially available for luminescence analysis using the method of the present invention and a conventional method. A Method of the Invention (1) 2 g of an aluminum analysis sample was placed in a 50 ml quartz flat-bottomed flask, and 10 g of platinum wire was added thereto. (2) 20 ml of an aqueous hydrochloric acid solution (1:1) was added, the surface was purified while stirring, the hydrochloric acid was removed, and the mixture was washed three times with water, twice with methanol, and once with ethanol in that order. Then, it was left in an oven at 60°C for 5 minutes to dry. (3) 0.4 g of anhydrous sodium sulfate was added to a dry graduated cylinder, and 18 ml of ethyl bromide and 0.05 ml of bromine solution were added thereto and stirred to perform dehydration treatment. (4) Only this dehydrated solution was added to the flask containing the sample, and a quartz Dimroth was placed above the flask. A column filled with magnesium perchlorate was attached to the air-open end of the Dimroth to prevent moisture absorption. In the Dimroth, cooling water of 6° C. or lower is flowed to reflux unreacted, vaporized ethyl bromide into the flask. (5) At the beginning of the reaction, heat to about 30°C using a mantle footer, and after the reaction starts, no particular heating is usually required due to the exothermic reaction. (6) After the solid aluminum had disappeared and everything in the reaction vessel had liquefied, the flask was held for several more minutes and then cooled to room temperature. (7) The Dimroth was removed from the flask, the platinum wire was taken out from the flask, and a vacuum distillation device was attached to the top of the flask. (8) Adjust the degree of vacuum inside the flask to 5 Torr or less using the connected vacuum pump, set the ribbon heater on the top of the flask to 70°C, and control the flask to 140°C with the mantle heater.
Distillation under reduced pressure was continued, and the distillation was stopped when no distillate remained. (9) After bringing the inside of the flask to normal pressure, the vacuum distillation apparatus was removed. Next, 10 ml of an aqueous hydrochloric acid solution (1:2) and 0.05 ml of concentrated nitric acid were added to the residue in the flask, placed on a hot plate, heated, and boiled for 20 to 30 seconds to dissolve the residue. (10) The resulting residual solution was subjected to simultaneous multi-element analysis using a plasma emission analyzer (Seiko Electronics Co., Ltd., SPS-1200A). B. Conventional method Here, quantitative analysis was performed using a method conforming to the chemical analysis method specified in the Light Metals Association standard "LIS". The analytical values obtained by these methods A and B are as follows:
As shown in the table, the analysis accuracy is 1 depending on the target element.
It can be seen that the improvement is from 1 to 2 orders of magnitude.

【table】

[Table] Example 2 A commercially available nominally 99.99% Al ingot was subjected to ethyl bromide treatment and vacuum distillation treatment under the same conditions as in Example 1, and then plasma emission analysis was performed. The results are shown in Table 2 below. It was as follows.

【table】

[Table] <Effects of the invention> By adopting this method, when compared with conventional analytical techniques, (1) fewer chemicals are used for analytical processing, there is no environmental pollution during analytical processing, and impurities to be analyzed are concentrated; Highly accurate analytical data can be obtained. (2) Analysis costs are low because no expensive special equipment is required for sample processing. (3) Elements other than Si and Ga are quantifiable and
Especially when using simultaneous multi-element analysis methods,
The total time required is greatly reduced. (4) When compared with chemical analysis methods, the required sample weight may be smaller. There are advantages such as

Claims (1)

[Claims] 1. After reacting ethyl bromide with a high-purity aluminum material in the presence of a platinum group catalyst and bromine, the resulting solution is distilled under reduced pressure to separate the organic aluminum compound, and the residue is used as a secondary sample for trace analysis. A method for analyzing trace impurities in high-purity aluminum.