CS263378B1 - The way of decomposing steel samples in particular to determine the total aluminum content - Google Patents

Abstract

The method of decomposition of steel samples, especially for determining the total aluminum content by atomic absorption spectrometry and spectrophotometric methods, according to the solution, consists in that the steel sample is decomposed in a hermetically sealed space by the action of hydrofluoric acid, nitric acid and hydrochloric acid in a ratio of 1:0.2:2 to 1:0.5:4 parts by volume at a temperature of 100 to 200 °C for 5 to 90 minutes.

Description

263378 2

The above mentioned drawbacks are eliminated by the method of decomposition of steel samples especially for the determination of the total aluminum range according to the invention. The essence of the invention is that the steel sample is placed in a pressure vessel to which a mixture of hydrofluoric acid with a concentration of 40, nitric, at a concentration of 65.8%, is added; and hydrochloric acid at a concentration of 36% by weight at a ratio of 1: 0.2: 2 to 1: 0.5: 4 by volume. Finally, the vessel is hermetically sealed and heated at 100 to 200 ° C for 5 to 90 minutes.

Using the method of decomposing the steels of the invention, the sample is decomposed by a single operation in which all of the aluminum forms present in the solution, i.e., metal aluminum, nitride bonded aluminum, and oxidically bonded aluminum pass into solution. The sample decomposition process is simplified and shortened. The need for using precious metal containers, especially platinum, is avoided. The possibility of contamination of the solution is reduced and the heavy salt concentration, especially when using the atomic absorption spectrometry method, is eliminated. The accuracy and determination of the total aluminum content after the decomposition of the samples according to the invention is better than the requirements of national and international standards. EXAMPLES Example 1

One gram of sample is weighed into a Teflon pressure vessel, 15 ml of a 40% by weight hydrogen fluoride mixture is added. , nitric acid 65 wt. and hydrochloric acid 36 wt. 1: 1: 3 parts by volume. The container is closed with the lid and inserted together with the fixture into the oven heated to 150 ° C. After 40 minutes, the device is removed, cooled under a stream of water and disassembled. To the Teflon pressure vessel is added 35 ml of boric acid solution (4 wt.%). The contents of the flask are transferred to a beaker and the necessary volume evaporated. Then transfer the contents of the beaker to a 50 ml volumetric flask and make up the water mark. The solution thus prepared is used to determine the total aluminum content of the steel by the atomic absorption spectrophotometry. Example 2

One gram of sample is weighed into a Teflon pressure vessel, 20 ml of a 40% by weight hydrofluoric acid mixture, 65% by weight of nitric acid is added. and hydrochloric acid 36 wt. 1: 0.25: 0.75 parts by volume. The vessel is sealed with a lid and inserted with a clamping device into the oven heated to 140 ° C. After 45 minutes the device is removed, cooled rapidly under a stream of water and disassembled. To a Teflon pressure vessel is added 50 ml of boric acid solution at a concentration of 4% by weight. Next, proceed as in Example 1. Example 3

One gram of sample is weighed into a Teflon pressure vessel, 20 ml of a 40% by weight mixture of hydrogen fluoride, 65% by weight of nitric acid is added. and hydrochloric acid 36 wt. in a 1: 2: 4 volume ratio. The vessel is sealed with the lid and inserted together with the fixture into the oven heated to 160 ° C. After 30 minutes, the device is removed, cooled rapidly under a stream of water and disassembled. To the Teflon pressure vessel was added 20 mL of a 4% strength boric acid solution. Furthermore, the procedure of Example 1 is followed. The accuracy and accuracy of the analysis results after the decomposition of the samples according to the invention is better determined by the requirements of national and international standards for determining the total aluminum and steel content. The average span of the parallel determinations of,, calculated from analyzes of 16 samples, is 0.001 5% aluminum for contents up to 0.15%. The Student's criterion t ^, calculated on the basis of analyzes of 6 samples with attested aluminum content, is less than the critical value t ^ = - 12.706 for 2 parallel determinations and 95% probability. The results of the scouring on 6 samples are attached.

Claims (4)

The invention can be used in all chemical laboratory applications for the analysis of industrial iron, especially steel, in particular in metallurgical plants, but only on the basis of the overall aluminum content, but also of the use of elements. , which occur in steel in the form of non-degradable acids, e.g., -sircon, without any special treatment or oxidation. i. Annex 1 Results Determined Aluminum Content in Standard Steel Samples Number Labeling and Origin AI Content in * Rosphere Calculated In '<:, Standa rdne jv zoxky attested by PV established parallel determinations R Student's value 1 2 8 in% criterion t 1 I0IJ 174/2 Japan 0.034 0.039 0.039 0.039 0 0.000 3.58 2 EURO 076-2 0.031 6 0.034 0.033 0.033 5 0.001 3.64 Euxopian community. 3 ISiJ 171/2 0.049 0.046 0.046 0.046 0 0.000 5.78 Japan 4 ÍSIJ 169/2 Japan 0,053 0,050 0,050 0,050 0 0,000 5,78 5 3CS 459 UK 0,068 0,070 0,069 0,069 5 0,001 2,87 6 BCS 322 UK 0,093 0,088 0,085 0,086 5 0,003 12,45 • ty = i- “—TJSl - Student's Characteristics for n = 2 and Pravdepod. 95% tk = 12,706) x - average value of element content in%, R μ - attested (correct) value of element content in% n - number of repeated determinations - standard deviation k - for 2 determination = 0,886 _n c R - average span k - number of analyzed samples SUBJECT MATERIAL Decomposition method of steel samples mainly for determination of total aluminum content characterized in that the steel sample is placed in a pressurized vessel to which is added a hydrogen fluoride mixture of 40% by weight, a nitric acid concentration of 65% by weight. and hydrochloric acid at a concentration of 36 wt. at a ratio of 1: 0.2: 2 to 1: 0.5: 4 by volume, to which the pressure vessel is hermetically sealed and heated at 100 to 200 ° C for 5 to 90 minutes.