Method for analyzing and detecting free carbon in chromium carbide

A detection method and technology for free carbon, which can be used in the preparation of test samples, and by removing certain components for weighing, etc., which can solve the problem of low accuracy of free carbon and achieve good precision.

Active Publication Date: 2008-12-24
ZHUZHOU HARD ALLOY GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the technical defects that the above-mentioned combustion gravimetric method is not accurate in measuring free carbon in chromium carbide, and the acid-soluble-gas volumetric method cannot measure free carbon at present because chromium carbide is difficult to dissolve, and provides a high-pressure decomposition c...

Method used

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  • Method for analyzing and detecting free carbon in chromium carbide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Embodiment 1: Determination of free carbon in chromium carbide (sample S-1)

[0025] Weigh 0.5000g (grams) of chromium carbide sample in a polytetrafluoroethylene sample-dissolving crucible, rinse the crucible wall with 1mL (milliliters) of deionized water, and then add in order the purity to be analytically pure and the mass concentration to be 1.14g / mL (grams) 10 mL of hydrofluoric acid (the same as in the following examples) and 1 mL of nitric acid with a purity of 1.42 g / mL (the same in the following examples) as analytically pure, and mix well, cover the crucible lid, and dissolve the sample in the crucible Put it into a stainless steel autoclave, tighten the lid of the autoclave, and heat the autoclave in a graphite furnace. When the temperature rises to 195-205°C, use a voltage regulator to adjust the voltage and keep it decomposed at this temperature for 120min (minutes). After the decomposition time is up, cool down and take out the autoclave, open the tank in...

Embodiment 2

[0028] Embodiment 2: Determination of free carbon in chromium carbide (sample S-2)

[0029] Weigh 0.5000g chromium carbide sample into a polytetrafluoroethylene crucible, add 1.5mL deionized water to rinse the crucible wall, then add 9mL hydrofluoric acid and 1.5mL nitric acid in sequence, mix well, cover the crucible lid, and put it into an autoclave , tightened, and the autoclave was placed in a graphite furnace for heating. When the temperature rises to 205-215°C, keep it at this temperature for 90 minutes to decompose. Then put the porcelain boat in an oven and bake at 120°C for 1.5h. After drying, measure the free carbon content in the sample with a 101-type carbon tester and calculate the free carbon content in the sample according to the above formula (1). The measurement results (X), mean value (x), standard deviation (S), and relative standard deviation (RSD) are shown in Table 2.

[0030] Table 2%

[0031] sample name

Embodiment 3

[0032] Embodiment 3: Determination of free carbon in chromium carbide (sample S-3)

[0033] Weigh 0.5000g of chromium carbide sample into a polytetrafluoroethylene crucible, add 2.0mL of deionized water to rinse the crucible wall, then add 7mL of hydrofluoric acid and 2mL of nitric acid in sequence, mix well, cover the crucible lid, and put it into an autoclave. Tighten, place the autoclave in a graphite furnace for heating. When the temperature rises to 215-225°C, keep it at this temperature for 70 minutes to decompose. Then put the porcelain boat in an oven, bake it at 150°C for 1 hour, measure it with a carbon analyzer after drying, and calculate the free carbon content in the sample according to the above formula (1). The measurement results (X), mean value (x), standard deviation (S), and relative standard deviation (RSD) are shown in Table 3.

[0034] table 3%

[0035] sample name

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Abstract

The invention provides an analysis detection method for free carbons in chromium carbide, comprising the steps as follows: a chromium carbide sample is arranged in a polytetrafluoroethylene crucible; after the crucible wall is washed by deionized water, hydrofluoric acid and nitric acid are sequentially added into the crucible and mixed uniformly; the crucible containing the hydrofluoric acid and the nitric acid are arranged inside a high-pressure kettle and subsequently heated in a graphite oven; samples are decomposed according to the given melting temperature, time and high pressure. After the decomposing and cooling, the chromium carbide sample solution and free carbons are transferred and washed cleanly to be arranged in a platinum extraction-filtration crucible which is padded by acid cleaning asbestoses; after the filtration and dryly pumping, the acid-cleaning asbestos pad and the free carbons are completely transferred into a porcelain boat; subsequently, the porcelain boat is arranged in baking box for drying; the dried porcelain boat is tested on a carbon content tester and the analysis result of the free carbon is calculated. The method of the invention adopts a mixed acid high-pressure decomposition method to solve the difficult problem that the chromium carbide is difficult to decompose, ensures that the free carbons are not dissolved, and has the testing range of 0.050 to 1.00 percent, good accuracy and precision.

Description

technical field [0001] The invention relates to a method for measuring free carbon by an acid-soluble-gas volumetric method, in particular to an analysis and detection method for free carbon in chromium carbide and refractory metals. Background technique [0002] The determination of free carbon in carbide is basically to use inorganic acid to completely dissolve carbide, and at the same time, free carbon is insoluble in acid, and the free carbon is separated by filtration, and then the amount of free carbon is measured by different carbon measuring instruments. Among the existing methods for measuring the amount of free carbon in a sample by the acid-soluble-gas volumetric method, there is no corresponding method for measuring the amount of free carbon in chromium carbide. Since chromium carbide is one of the important additives for inhibiting grain growth in cemented carbide production, its carbon content directly affects the performance of cemented carbide. Both productio...

Claims

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Application Information

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IPC IPC(8): G01N5/04G01N1/44
Inventor 蒋亚芳
Owner ZHUZHOU HARD ALLOY GRP CO LTD
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