JB/T 7948.5-1999 JB/T 7948.5-1999 Chemical analysis method for melting flux Sulfosalicylic acid photometric method for determination of iron oxide content JB/T7948.5-1999 Standard download decompression password: www.bzxz.net

JB/T 7948.5—1999
This standard is equivalent to JB/T22978.1~22978.10—78 "Methods for chemical analysis of melting flux" This standard is a replacement for JB/T7948.5--95 "Methods for chemical analysis of melting flux - determination of iron oxide content by sulfosalicylic acid photometry". During the revision, only editorial changes were made to the standard, and its technical content has not changed. This standard replaces JB/T7948.5-95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Welding Standardization. The drafting unit of this standard: Harbin Welding Research Institute. The main drafters of this standard: Lin Kegong and Bai Shuyun. 364
1 Range
Standard of the Machinery Industry of the People's Republic of China
Methods for chemical analysis of melted welding fluxesThe sulfosalicylic acid photometric methodfor determination of iron oxide contentJB/T7948.5—1999
Replaces JB/T7948.5—95
This standard applies to the determination of iron oxide content in melted welding fluxes. Determination range: 0.10%~~1.50%. This standard complies with GB/T14671978 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T1467-1978 General and general provisions of the standard for chemical analysis of metallurgical products JB/T7948.2-1999 Chemical analysis method for melting flux Potentiometric titration method for determination of manganese oxide content 3 Method summary
This method is based on the formation of a yellow complex between iron ions and sulfosalicylic acid in an ammonia medium with a pH of 8 to 12. The absorbance is measured at a wavelength of 430 to 435 mm on a spectrophotometer to determine the percentage of iron oxide. The influence of manganese can be eliminated by adding hydroxylamine hydrochloride. 4 Reagents
4.1 Nitric acid (specific gravity 1.42).
4.2 Hydrochloric acid (1+1).
4.3 Ammonium hydroxide (1+4).
4.4 Hydroxylamine hydrochloride solution (10%). Prepare when needed. 4.5 Sulfosalicylic acid solution: Weigh 20g sulfosalicylic acid (C,HOS·2H,0) and dissolve in 100mL water. Filter. 4.6 Congo red test paper.
4.7 Iron standard solution: Weigh 1.0000g pure iron (99.98% or more) and dissolve in 30mL hydrochloric acid (4.2), add a few drops of nitric acid (4.1) to oxidize, and boil to remove nitrogen oxides. Cool, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. This solution contains 1.0mg iron per mL.
4.8 Iron standard solution: Transfer 10.00ml. Iron standard solution (4.7) to a 200mL volumetric flask, dilute to scale with water, and mix. This solution contains 0.05mg iron per mL.
Approved by the State Bureau of Machinery Industry on June 24, 1999, and implemented on January 1, 2000
5 Photograph
Spectrophotometer.
6 Sample
JB/T7948.5-1999
The sample should pass through a 200-mesh screen. Pre-dry at 105-110℃ for 1 hour, place in a desiccator and cool to room temperature 7 Analysis steps
7.1 Determination quantity
Three samples should be weighed for determination during analysis, and the average value should be taken. 7.2 Sample quantity
Weigh 0.5000g of sample, and follow the steps 7.3.1 to 7.3.5 of JB/T7948.2-1999 to transfer 20.00mL of test solution. 7.3 Determination
7.3.1 Place the test solution (7.2) in a 100mL volumetric flask, add 15mL of hydroxylamine hydrochloride solution (4.4) and 10mL of sulfosalicylic acid solution (4.5), neutralize the solution with ammonium hydroxide (4.3) until the Congo red test paper changes from blue to red (the solution is yellow), then add 10hL in excess, dilute to the mark with water, and mix.
7.3.2 Transfer part of the solution (7.3.1) to a 2cm colorimetric plate, use the reagent blank as a reference, and measure its absorbance at a wavelength of 430~435nm on a spectrophotometer. Find the corresponding amount of iron from the working curve. 7.4 Drawing of working curve
Pipette 1.00 mL: 2.00 mL; 3.00 mL: 4.00 mL, 5.00 mL 6.00 mL; 7.00 mL 8.00 mL of iron standard solution (4.8), place them in a set of 100 mL volumetric flasks, and operate according to steps 7.3.1~7.3.2. Draw the working curve with the amount of iron as the abscissa and the absorbance as the ordinate. www.bzxz.net
8 Calculation of analysis results
Calculate the percentage of iron oxide according to formula (1): Fe2O
In the formula, m
9 allows the whole
of the iron amount found on the working curve, g
iron is converted into the conversion factor of iron oxide;
Pipette the amount of test solution equivalent to the sample,.
X1.429 7X100%
The difference between parallel results should not be greater than the allowable difference listed in Table 1. Table 1 allowable difference
Iron oxide content
:0. 10~0. 20
≥0. 200. 40
>0+ 40~0. 80
>0.80~1.50
Allowable difference
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