CN105572116A

CN105572116A - Determination method of aluminum in silicon-aluminum alloy

Info

Publication number: CN105572116A
Application number: CN201510905525.4A
Authority: CN
Inventors: 战丽君; 刘钢耀; 刘建华; 张俊杰; 周欣
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2015-12-10
Filing date: 2015-12-10
Publication date: 2016-05-11

Abstract

The invention relates to a determination method of aluminum in silicon-aluminum alloy. The determination method is characterized in that nitric acid, hydrochloric acid and hydrofluoric acid are adopted to dissolve a test specimen, boracic acid is added to eliminate the interference of fluorinion, perchloric acid smokes, insoluble residues are processed, and then, an EDTA (Ethylene Diamine Tetraacetic Acid) volumetric method is adopted to determine the content of the aluminum. The determination method has the advantages that operation is easy in mastering and the repeatability and the accuracy of determination results are higher than those of a strong alkali fusion method since a low-temperature electric hot plate is used for dissolving the test specimen.

Description

Al-single crystal method in silicon-aluminium alloy

Technical field

The present invention relates to a kind of Al-single crystal method in silicon-aluminium alloy, belong to metallurgical analysis technical field.

Background technology

Silicon-aluminium alloy, can be used for deoxidation in STEELMAKING PRODUCTION, because silicon-aluminium alloy density ratio fine aluminium density is large, more easily enter molten steel, inner scaling loss is few, can improve inclusion morphology, reduces elemental gas content in steel, improve steel quality, reduce costs, economize on aluminum amount, be specially adapted to continuous casting steel deoxidation requirement, there is desulfurization performance, the advantages such as penetration power is strong.Silicon-aluminium alloy also has good casting character and anti-wear performance, and coefficient of thermal expansion is little, is the alloy that in Birmasil, kind is maximum, consumption is maximum.Be widely used in structural member, as housing, cylinder body, casing and framework etc.Wherein, the exact level of aluminium plays very important effect.

Summary of the invention

The object of this invention is to provide and a kind of there is good precision, accuracy, for steel-making Composition Control process provides accurate data, meet Al-single crystal method in the silicon-aluminium alloy of modern production and scientific research needs.

Technical scheme of the present invention is as follows:

Adopt nitric acid, hydrochloric acid, hydrofluoric acid dissolution sample, add the interference of boric acid elimination fluorine ion, perchloric acid smoked, after process undissolved residue, with the content of EDTA volumetric determination aluminium.

Beneficial effect of the present invention:

1) accurate:

When the decomposition of this type of sample adopts highly basic fusion method, sample melts and affects by melting time, melt temperature, operating conditions harshness.When adopting acid-soluble method, because silicone content is high, need add hydrofluorite, hydrofluorite easily coordinates with aluminium, and not easily catch up with to the greatest extent with perchloric acid smoked fluorine ion, the fluorine ion residual when titration easily produces interference.This method added appropriate boric acid and coordinates with fluorine ion before emitting perchloric acid cigarette, can eliminate the interference of fluorine ion, if carry out residue treatment after having insolubles to smolder, then adopted during aluminium in EDTA volumetric determination silicon-aluminium alloy sample and had good accuracy.

2) deal with problems:

A. invent the content that a kind of method measures aluminium in silicon-aluminium alloy, can modern production be met.

B. because hydrofluorite easily coordinates with aluminium, high alumina sample perchloric acid smoked fluorine ion is not easily caught up with to the greatest extent, and the fluorine ion residual when titration easily produces interference.Add boric acid after molten sample and eliminate this interference.

C. can not consoluet silicon-aluminium alloy sample through acid, measurement result accurately and reliably can be measured after carrying out residue treatment.

D. highly basic fusion method measures the equipment of silicon-aluminium alloy sample use is high temperature smelting furnace, and affect by melting time, melt temperature during sample melting, operating conditions is harsh.This method uses low temp. electric hot plate dissolved samples, and operation is easily grasped, and measurement result repeatability, accuracy are higher than highly basic fusion method.

Embodiment

1. method summary

Sample adopts hydrochloric acid, nitric acid, hydrofluorite to decompose, and add boric acid, perchloric acid smoked, sample has residue to carry out residue treatment, with highly basic by element sepatation such as aluminium and iron, manganese, titanium, calcium, magnesium, adds excessive EDTA, makes it completely and aluminium coordination.In the medium of pH=4.5, take PAN as indicator, with after the EDTA that copper sulphate standard solution residual titration is excessive, add the EDTA of sodium fluoride release and aluminium coordination, then use copper sulphate standard solution residual titration, according to standard solution consumption, calculate the mass percent of full aluminium.

2. reagent

Fine aluminium (99.99%)

Hydrochloric acid (ρ 1.19g/mL)

Hydrochloric acid (volume ratio 1:1)

Nitric acid (ρ 1.42g/mL)

Hydrofluorite (ρ 1.15g/mL)

Perchloric acid (ρ 1.67g/mL)

NaOH (200g/L)

NaOH (solid)

Sodium fluoride (solid)

Boric acid (solid)

Mixed flux (2 parts of natrium carbonicum calcinatums+1 part of boric acid)

Acetic acid-ammonium acetate buffer solution:: add 80mL acetic acid after 77g ammonium acetate is water-soluble, in 1000mL volumetric flask, be diluted to scale (PH=4.5), shake up.

Congored test paper

PAN indicator (0.1% ethanolic solution)

EDTA standard solution: C (EDTA)=0.018mol/L

Copper sulphate standard solution: C (CuSO ₄)=0.018mol/L

2.2 experimental technique

Take 0.2000g test portion (being accurate to 0.0001g) and be placed in 300mL polytetrafluoroethylene beaker, add 10mL hydrochloric acid (ρ 1.19g/mL), 10mL nitric acid (ρ 1.42g/mL), 3 ~ 5mL hydrofluorite (ρ 1.15g/mL), to be placed on low temp. electric hot plate after heat resolve, add 2g boric acid (solid), shake up, move in 300mL beaker with water, add 10mL perchloric acid (ρ 1.67g/mL), smolder dry to the greatest extent, slightly cold, add 20mL hydrochloric acid (volume ratio 1:1) dissolved salts, dilute with water volume is to 100mL.

Note: if there is undissolved residue, filters with the middling speed qualitative filter paper being added with pad angle, wipes to the greatest extent beaker with the glass bar with rubber tip, and with hot wash filter paper and residue 3 ~ 4 times, filtrate and wash pools, in 300mL beaker, give over to main liquid.

Residue is placed in platinum crucible together with filter paper, low-temperature heat charing, ashing.Burn 20min in 900 DEG C of high temperature furnaces, takes out, cooling.Add 2g mixed flux.Platinum crucible is placed in 900 ~ 950 DEG C of high temperature furnace melting 10 ~ 15min, takes out, cooling, is placed in main liquid and dissolves fused mass, wash platinum crucible and take out.

Control at 100 ~ 150mL by above liquor capacity, be adjusted to oxyhydroxide occur with NaOH (200g/L), after hydro-oxidation sodium 8g, heating is boiled, is cooled, and moves in 250mL volumetric flask, is diluted to scale, shakes up.

After dry for above-mentioned solution filtration, divide and get 50.00mL test solution in 500mL triangular flask, add EDTA standard solution (0.018mol/L) 50mL, add Congored test paper one piece, be adjusted to test paper with hydrochloric acid (volume ratio 1:1) and become blue look, add 50mL acetic acid-ammonium acetate buffer solution, boil 3min, take off, add 8 PAN(1at%) indicator, be titrated to solution with copper sulphate standard solution (0.018mol/L) and become purple (not remembering reading).Add 2 ~ 3g sodium fluoride (solid), 3min is boiled in heating, adds PAN(1%) indicator 4, be titrated to solution with copper sulphate standard solution (0.018mol/L) and become purple, the standard solution volume that note consumes is V.

Note: during by hydrochloric acid adjustment acidity, as solutions turbid, show that EDTA standard solution addition is not enough, alkalescence can be adjusted to again and add appropriate EDTA standard solution.

2.3 calculate

In formula: the massfraction of W (Al) %-aluminium, %;

The volume of copper sulphate standard solution is consumed, mL during V-titration sample;

V ₀the volume of copper sulphate standard solution is consumed, mL when-titration is blank;

T-copper sulphate standard solution to the titer of aluminium, g/mL;

M-point to get test solution institute quite sample size, g;

Note: copper sulphate standard solution (0.018mol/L): take the fine aluminium close with aluminium percentage composition in sample (99.99%) two part, with sample synchronous operation, the volume of two parts of solution consumption copper sulphate standard solution is averaged.

The titer of copper sulphate standard solution to aluminium is calculated as follows:

In formula: T-copper sulphate standard solution to the titer of aluminium, g/mL;

The quality of m-point to get fine aluminium in test solution (99.99%), g;

V ₁-titration fine aluminium test solution consumes the mean value of copper sulphate standard solution volume, mL;

V ₀the volume of copper sulphate standard solution is consumed when-titration is blank.

3 results and discussion

The selection of 3.1 boric acid additions

Take silicon-aluminium alloy standard model 0.2000g, the boric acid that empirically method adds different amount is tested, and the results are shown in Table 1:

The selection of table 1 boric acid addition

From upper table data, boric acid addition is at more than 1g, and titration end-point is easily observed, and determination data accurately and reliably.This method is selected to add 2g boric acid.

3.2 different analytical approach working sample result control experiments:

Take silicon-aluminium alloy sample 0.2000g two parts, adopt this method and highly basic fusion method to measure respectively, carry out method control experiment, the results are shown in Table 3, table 4:

The control experiment of table 3 distinct methods

The control experiment of table 4 distinct methods

As seen from the above table, this method is adopted accurately can to measure the content of aluminium in silicon-aluminium alloy sample.If sample must carry out residue treatment when acid dissolve is incomplete, otherwise measurement result is on the low side.

4 sample analysis

The precision of 4.1 methods

Adopt silicon-aluminium alloy sample, empirically method is carried out Precision Experiment (n=9) and be the results are shown in Table 5:

Table method precision is tested

Measure precision result from table 5, the RSD of the method is all less than 5%, therefore has good precision.

The accuracy of 4.2 methods

Adopt silicon-aluminium alloy standard model, empirically accuracy experiment is carried out in method operation, the results are shown in Table 6:

Table method accuracy is tested

Sample name and numbering	Element	Sample weighting amount (g)	Standard value (%)	Measured value (%)	With the difference (%) of scale value
						Silicon-aluminium alloy (08-81)	Al	0.2000	34.88	34.93	0.05
Silicon-aluminium alloy (8901)	Al	0.2000	48.64	48.56	0.08

From table 6 measurement result, the method can ensure the accuracy of testing result.

5 conclusions

Shown by a large amount of experimental datas: the method can measure the content of aluminium in silicon-aluminium alloy, have operation and easily grasp, measurement result accuracy, precision advantages of higher, can meet production testing requirement completely.

Claims

1. an Al-single crystal method in silicon-aluminium alloy, is characterized in that: adopt nitric acid, hydrochloric acid, hydrofluoric acid dissolution sample, add the interference of boric acid elimination fluorine ion, perchloric acid smoked, after process undissolved residue, with the content of EDTA volumetric determination aluminium.