WARNING: The personnel using this Part shall have practical experiences in regular laboratory work. This Part does not point out all the possible safety problems. Users have the responsibility to take appropriate safety and health measures and also ensure meeting the conditions specified in relevant regulations of the State.
1 Scope
This Part of GB/T 223 specifies the chrome azurol S photometric method for the determination of the acid-soluble aluminium content and the cupferron separation-chrome azurol S photometric method for the determination of the aluminium content.
Method I of this Part is applicable to the determination of the acid-soluble aluminium content which mass fraction is 0.050%~1.00% in the iron, steel and alloy; Method II of this Part is applicable to the determination of the aluminum content which mass fraction is 0.015%~0.50% in the iron, steel and alloy.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this Part of GB/T 223. For dated references, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties whose enter into an agreement according to this Part are encouraged to research whether the latest editions of these documents are applied or not. For undated references, the latest edition of the normative document is applicable to this Part.
GB/T 6379.1 Accuracy (Trueness and Precision) of Measurement Methods and Results-Part 1: General Principles and Definitions
GB/T 6379.2 Accuracy (Trueness and Precision) of Measurement Methods and Results-Part 2: Basic Method for the Determination of Repeatability and Reproducibility of a Standard Measurement Method
GB/T 20066 Steel and Iron-Sampling and Preparation of Samples for the Determination of Chemical Composition
3 Method I Chrome Azurol S Direct Photometric Method
3.1 Principle
Measure the absorbance of the aubergine complex compound generated by the aluminum and chrome azurol S in the faintly acid medium with pH value (5.3~5.9) after the test portion is dissolved with the acid.
Noninterference determination containing 100μg vanadium and 2mg chromium in the color reagent. The iron and nickel interference may be sheltered with Zn-EDTA; 300μg titanium may be sheltered with 0.15g mannite.
3.2 Reagents and Materials
During the analysis, unless otherwise stated, only the recognized analytical reagent and the distilled water or the water of equivalent purity with the distilled water shall be used.
3.2.1 Pure iron, free from aluminum or with a known residual aluminum content.
3.2.2 Hydrochloric acid, ρ is about 1.19g/mL.
3.2.3 Hydrochloric acid, ρ is about 1.19g/mL, diluted in 5+95.
3.2.4 Nitric acid, ρ is about 1.42g/mL.
3.2.5 Perchloric acid, ρ is about 1.67g/mL.
3.2.6 Mannite solution, 50g/L.
3.2.7 Hexamethylenetetramine solution, 400g/L, stored in the plastic bottle.
3.2.8 Ammonium fluoride solution, 5g/L, stored in the plastic bottle.
3.2.9 Chrome azurol S solution, 0.5g/L.
3.2.10 Zinc ethylene diamine tetraacetic acid (Zn-EDTA) solution: weigh 8.1g zinc oxide, place them in a beaker, add 40mL of hydrochloric acid (1+1) and heat them until they are dissolved. Weigh another 37.2g EDTA (containing two crystal water) to dissolve them in 800mL of water, add 15mL of ammonia water (ρ is about 0.90g/mL). Combine the two solutions and mix them up, adjust the solution with ammonia water (1+1) and hydrochloric acid (1+1) to pH value (4~6), dilute it with water to 1L and mix.
3.2.11 Ferrum solution: weigh 0.1g pure iron; place them in the quartz beaker. Add 6mL of hydrochloric acid (3.2.2) and 1mL of nitric acid (3.2.4), heat them until they are dissolved, cool them. Transfer them in a 100mL volumetric flask; dilute them with water to the scale and mix. 1mL of this solution contains 1mg iron.
3.2.12 Nickel solution: weigh 0.1g pure nickel; place them in the quartz beaker. Add 10mL of nitric acid (1+1); heat them until they are dissolved and cool. Transfer them in a 100mL volumetric flask; dilute them with water to the scale and mix. 1mL of this solution contains 1mg nickel.
3.2.13 Cobalt solution: weigh 0.1g pure cobalt; place them in the quartz beaker. Add 4mL of hydrochloric acid (3.2.2) and 4mL of nitric acid (3.2.4), heat them until they are dissolved and cool. Transfer them in a 100mL volumetric flask; dilute them with water to the scale and mix. 1mL of this solution contains 1mg cobalt.
GB/T 223.9-2008 The following standards are cited：
