阅读说明：本技术 一种测定锌及锌合金中镁含量的方法 (Method for measuring magnesium content in zinc and zinc alloy ) 是由 张亮亮 吴锐红 于 2019-11-15 设计创作，主要内容包括：一种测定锌及锌合金中镁含量的方法,包括：称取样品,向样品中加入稀盐酸,待样品的剧烈反应停止后,将样品置于低温电炉上加热继续溶解,直至样品溶解完全,室温冷却后加入水；向处理后的样品中加入干扰消除剂,采用水对混合溶液进行定容,摇匀得到待测样品；火焰原子吸收光谱仪依次吸入空白溶液和镁标准系列溶液,分析测定吸光值并绘制工作曲线；吸入待测样品,根据待测样品的吸光值在镁含量的工作曲线上查找得出待测样品中的镁含量。采用LaCl<Sub>3</Sub>、SrCl<Sub>2</Sub>或8-羟基喹啉中的一种作为干扰消除剂,能在极大程度上减少铝在吸光值测定时对镁元素的干扰；操作简单,检出限低,准确度高、线性范围广,能满足锌及锌合金中镁的测定要求。(A method for determining the magnesium content in zinc and zinc alloys comprises the following steps: weighing a sample, adding dilute hydrochloric acid into the sample, placing the sample on a low-temperature electric furnace for heating and continuously dissolving after the violent reaction of the sample is stopped until the sample is completely dissolved, and adding water after cooling at room temperature; adding an interference elimination agent into the treated sample, adopting water to perform constant volume on the mixed solution, and shaking up to obtain a sample to be detected; the flame atomic absorption spectrometer sequentially sucks the blank solution and the magnesium standard series solution, analyzes and determines a light absorption value and draws a working curve; and (4) sucking a sample to be detected, and searching the working curve of the magnesium content according to the light absorption value of the sample to be detected to obtain the magnesium content in the sample to be detected. By using LaCl 3 、SrCl 2 Or one of 8-hydroxyquinoline is used as an interference eliminator, so that the interference of aluminum on magnesium element in the light absorption value measurement can be greatly reduced; simple operation, low detection limit, high accuracy and wide linear range, and can meet the requirement of measuring magnesium in zinc and zinc alloy.)

1. A method for measuring the content of magnesium in zinc and zinc alloy is characterized by comprising the following steps:

step 1, weighing a sample, adding dilute hydrochloric acid into the sample, after the violent reaction of the sample is stopped, placing the sample on a low-temperature electric furnace to be heated and continuously dissolved until the sample is completely dissolved, and adding water after the sample is cooled at room temperature;

step 2, adding an interference elimination agent into the sample treated in the step 1, adopting water to perform constant volume on the mixed solution, and shaking up to obtain a sample to be detected;

step 3, preparing a blank solution and a magnesium standard series solution;

step 4, the flame atomic absorption spectrometer sequentially sucks the blank solution and the magnesium standard series solution, analyzes and determines a light absorption value and draws a working curve;

and 5, sucking the sample to be detected by the flame atomic absorption spectrometer, and searching the working curve obtained in the step 4 according to the light absorption value of the sample to be detected to obtain the magnesium content in the sample to be detected.

2. The method for measuring the magnesium content in zinc and zinc alloys according to claim 1, wherein in the step 1, the sample weighing amount is 0.050 to 0.200g, and the ratio of the sample to the dilute hydrochloric acid is 1 g: 100 mL.

3. The method for determining the magnesium content in zinc and zinc alloys according to claim 1, wherein in step 1, if the sample is not completely dissolved, 30% hydrogen peroxide is added to the sample.

4. The method for determining the content of magnesium in zinc and zinc alloys according to claim 1, wherein the interference eliminator added in step 2 is LaCl₃、SrCl₂Or 8-hydroxyquinoline.

5. The method for determining the content of magnesium in zinc and zinc alloy according to claim 1, wherein in the step 2, the addition amount of the interference elimination agent is 5.0-20.0 mL, and the ratio of the sample to the interference elimination agent is 1 g: 100 mL.

6. The method for measuring the magnesium content in zinc and zinc alloy according to claim 1, wherein the specific process for preparing the blank solution in the step 3 is as follows:

adding 2.5-10.0 mL of dilute hydrochloric acid into a 100mL volumetric flask, wherein the ratio of the sample to the hydrochloric acid is 1 g: 50mL, adding an interference elimination agent, performing constant volume with water, and shaking up to obtain a blank solution.

7. The method for measuring the magnesium content in zinc and zinc alloy according to claim 1, wherein the specific process for preparing the magnesium standard series solution in the step 3 is as follows: adding standard solutions with different magnesium contents into a plurality of 100ml volumetric flasks, wherein the standard solutions comprise zinc alloy standard sample solutions and mixed solutions of the zinc alloy standard sample solutions and the magnesium standard solutions, then adding interference elimination agents with the same volume into each volumetric flask, and performing constant volume on the mixed solutions by adopting ultrapure water to obtain magnesium standard series solutions.

8. The method of claim 1, wherein in steps 4 and 5, the elemental lamp is preheated for 5min before the flame atomic absorption spectrometer analysis, so that the stabilized current is 6mA and the energy is 51 counts.

9. The method for measuring the content of magnesium in zinc and zinc alloy according to claim 1, wherein in the steps 4 and 5, the working parameters of the instrument are as follows: the analysis line is 285.21nm, the slit width is 0.7nm, the absorption signal type AA, the calculation mode is TimeAverage, the acetylene flow is 2.50L/min, the air flow is 10.00L/min, and the measurement times are 3 times.

Technical Field

The invention belongs to the technical field of detection methods, and relates to a method for measuring the content of magnesium in zinc and zinc alloy.

Background

The use of zinc and zinc alloy in nonferrous metals is second to copper and aluminum, and the zinc and zinc alloy is widely applied to the fields of automobiles, household appliances, light industry, machinery, batteries and the like. Generally, the mass fraction of zinc in pure zinc is 99.0-99.9%, and the highest zinc can reach 99.99%, while zinc alloy is a non-ferrous alloy formed by adding aluminum, copper, magnesium and other elements into zinc as a matrix, and can be divided into zinc-aluminum alloy and zinc-copper alloy according to the components, wherein the mass fraction of aluminum is generally 0.2-16%, the mass fraction of copper is 0.2-5.5%, iron is not more than 0.3%, and other elements are trace impurities. Although magnesium in the zinc alloy is doped as a trace element, the doping of the trace magnesium can refine the structure, thereby enhancing the strength of the alloy, and simultaneously reducing intergranular corrosion and improving the wear resistance of the alloy. However, if the content of magnesium in the zinc alloy is more than 0.08%, the toughness of the alloy is lowered, the fluidity of the alloy is deteriorated, and the alloy is liable to have unfavorable behaviors such as oxidation loss in a molten state. Magnesium is used as a necessary element in zinc alloy, so that an analysis method which is easy to operate and accurate in measurement is necessary.

Although the determination of the magnesium content in the zinc alloy has been reported, the interference of coexisting elements on magnesium elements exists in the testing process, so that the testing result is inaccurate; in addition, the measurement range of the magnesium content in the existing zinc alloy is narrow, and the application is limited.

Disclosure of Invention

The invention aims to provide a method for measuring the content of magnesium in zinc and zinc alloy, which solves the problem of inaccurate test result caused by the interference of coexisting elements in a method for measuring magnesium alloy on magnesium element.

The technical scheme adopted by the invention is as follows: a method for measuring the content of magnesium in zinc and zinc alloy comprises the following steps:

step 1, weighing a sample, adding dilute hydrochloric acid into the sample, after the violent reaction of the sample is stopped, placing the sample on a low-temperature electric furnace to be heated and continuously dissolved until the sample is completely dissolved, and adding water after the sample is cooled at room temperature;

step 2, adding an interference elimination agent into the sample treated in the step 1, adopting water to perform constant volume on the mixed solution, and shaking up to obtain a sample to be detected;

step 3, preparing a blank solution and a magnesium standard series solution;

step 4, the flame atomic absorption spectrometer sequentially sucks the blank solution and the magnesium standard series solution, analyzes and determines a light absorption value and draws a working curve;

and 5, sucking a sample to be detected, and searching the working curve obtained in the step 4 according to the light absorption value of the sample to be detected to obtain the magnesium content in the sample to be detected.

The invention is also characterized in that:

in the step 1, the sample weighing amount is 0.050-0.200 g, and the ratio of the sample to the dilute hydrochloric acid is 1 g: 100 mL.

In step 1, if the sample is not completely dissolved, 30% hydrogen peroxide may be added to the sample.

In the step 2, the added interference elimination agent is LaCl₃、SrCl₂Or 8-hydroxyquinoline.

In the step 2, the addition amount of the interference elimination agent is 5.0-20.0 mL, and the proportion of the sample to the interference elimination agent is 1 g: 100 mL.

In step 3, the specific process for preparing the blank solution is as follows:

adding 2.5-10.0 mL of dilute hydrochloric acid into a 100mL volumetric flask, wherein the ratio of the sample to the hydrochloric acid is 1 g: 50mL, adding an interference elimination agent, performing constant volume with water, and shaking up to obtain a blank solution.

The specific process for preparing the magnesium standard series solution in the step 3 comprises the following steps: adding standard solutions with different magnesium contents into a plurality of 100ml volumetric flasks, wherein the standard solutions comprise zinc alloy standard sample solutions and mixed solutions of the zinc alloy standard sample solutions and the magnesium standard solutions, then adding interference elimination agents with the same volume into each volumetric flask, and performing constant volume on the mixed solutions by adopting ultrapure water to obtain magnesium standard series solutions.

In steps 4 and 5, before the flame atomic absorption spectrometer is used for analysis, the element lamp is preheated for 5min, so that the stabilized current is 6mA, and the energy is 51 counts.

In steps 4 and 5, the working parameters of the instrument are as follows: the analysis line is 285.21nm, the slit width is 0.7nm, the absorption signal type AA, the calculation mode is Time Average, the acetylene flow is 2.50L/min, the air flow is 10.00L/min, and the measurement times are 3 times.

The invention has the beneficial effects that: the method for measuring the magnesium content in zinc and zinc alloy adopts LaCl₃、SrCl₂Or one of 8-hydroxyquinoline as interference eliminatorThe remover can greatly reduce the interference of aluminum on magnesium element during the measurement of light absorption value; simple operation, low detection limit, high accuracy and wide linear range, and can meet the requirement of measuring magnesium in zinc and zinc alloy.

Drawings

FIG. 1 is a graph of the working curve (SrCl) of an example of a zinc alloy in accordance with a method of the present invention for determining the magnesium content of zinc and zinc alloys₂As an interference eliminator).

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a method for measuring the magnesium content in zinc and zinc alloy, which comprises the following steps:

step 1, weighing 0.050-0.200 g of sample into a 100mL conical flask, adding 5.0-20.0 mL of dilute hydrochloric acid (the volume ratio of acid to water is 1: 1) into the sample to dissolve the sample, wherein the ratio of the sample to the dilute hydrochloric acid is 1 g: 100 mL. After the violent reaction of the sample is stopped, placing the conical flask on a low-temperature electric furnace to be heated and continuously dissolved until the sample is completely dissolved, dropwise adding 2-4 drops of 30% hydrogen peroxide if the sample is not completely dissolved, cooling at room temperature, and adding ultrapure water along the wall of the conical flask;

step 2, adding 5.0-20.0 mL of interference elimination agent into the sample treated in the step 1, wherein the ratio of the sample amount to the interference elimination agent is 1 g: 100 mL. Mixing, transferring into a glass volumetric flask, performing constant volume on the mixed solution by adopting ultra-pure water, and shaking up to obtain a sample to be measured; the interference eliminator is LaCl₃、SrCl₂Or 8-hydroxyquinoline.

Step 3, preparing a blank solution: adding 2.5-10.0 mL of dilute hydrochloric acid into a 100mL volumetric flask, wherein the ratio of the sample to the hydrochloric acid is 1 g: 50mL, adding an interference elimination agent, performing constant volume on the mixture by using ultrapure water, and shaking up to obtain a blank sample to be detected;

step 4, preparing a magnesium standard series solution: adding standard solutions with different magnesium contents into a plurality of 100ml volumetric flasks, wherein the standard solutions comprise zinc alloy standard sample solutions and mixed solutions of the zinc alloy standard sample solutions and the magnesium standard solutions, then adding interference elimination agents with the same volume into each volumetric flask, and performing constant volume on the mixed solutions by adopting ultrapure water to obtain magnesium standard series solutions;

step 5, the flame atomic absorption spectrometer sequentially sucks a blank solution and a magnesium standard series solution, and analyzes and draws a working curve, wherein the abscissa is the concentration value of magnesium, and the ordinate is the light absorption value;

and 6, sucking the sample to be detected by the flame atomic absorption spectrometer to obtain the magnesium content of the sample to be detected, and automatically drawing a working curve according to the analysis result of the flame atomic absorption spectrometer by adopting software and displaying the magnesium content of the sample to be detected

Preheating an element lamp for 5mins before each measurement and analysis, wherein the current after stabilization is 6mA, and the energy is 51 counts; the parameters of the flame atomic absorption spectrometer are as follows: the analysis line is 285.21nm, the slit width is 0.7nm, the absorption signal type AA, the calculation mode is Time Average, the acetylene flow is 2.50L/min, the air flow is 10.00L/min, and the measurement times are 3 times.

The present invention performs the following selection test for the acid and interference eliminator for dissolving the sample:

in order to compare the effect of different sample-dissolving acids on the interference elimination agent and the influence on the determination result of the alloy sample, the invention respectively adds different types of interference elimination agents into the zinc alloy Z50 (the magnesium content is 0.0238%) sample solution dissolved by the dilute hydrochloric acid and the dilute nitric acid and performs analysis, and the determination result is shown in tables 2 and 3.

TABLE 1 test results of different interference cancellers on nitric acid dissolved zinc alloy samples

Table 2 test results of different interference cancellers on zinc alloy samples dissolved in hydrochloric acid

From the analysis results in tables 1 and 2, it can be seen that:

1) by adding different types of salt solutions into a zinc alloy sample solution, SrCl in a nitric acid medium is obtained₂、LaCl₃The citric acid and the ascorbic acid obviously increase the light absorption value of the magnesium element in the zinc alloy; in hydrochloric acid medium, except SrCl₂、LaCl₃Besides salt solutions such as citric acid and ascorbic acid, 8-hydroxyquinoline also obviously increases the light absorption value of magnesium element in the zinc alloy.

2) In this experiment, 5% hydrochloric acid (acid to water volume ratio 1: 20, the same below) is less than the absorbance (0.0063) of 5% nitric acid, and the absorbance of magnesium measured in a zinc alloy sample dissolved by hydrochloric acid is basically higher than that measured after the sample is dissolved by nitric acid under the action of the same type of salt solution, so that the action effect of hydrochloric acid is better than that of nitric acid. Therefore, hydrochloric acid dissolution was used for the experiments. In addition, physical interference of acid can be eliminated by uniformly adding acid.

Interference determination

In order to clarify the interference of the possible coexisting elements in zinc and zinc alloy to magnesium, the coexisting elements are judged to be interference. Prior to the experiment, 14 100mL volumetric flasks were prepared in advance, 1^#Volumetric flask with ultrapure water as calibration blank, 2^#～14^#5mL of 10mg/L magnesium standard solution is added into the volumetric flask, and then the mixture is added to the flask to form a mixture with the concentration of 3^#～14^#The single element standard solutions with the corresponding sequence numbers in the table 4 are sequentially added into the volumetric flask, and after constant volume shaking up, analysis is performed.

The ratio of the net absorbance of the mixed solution obtained by mixing a single coexisting element with 0.5mg/L magnesium standard solution to the absorbance of the pure magnesium standard solution is recorded as an interference factor f, and the interference degree of the coexisting element on magnesium is represented by the value.

TABLE 3 interference test of pure solution of single element on magnesium

Note: the concentration of each element in the list is the concentration value of the single element in the solution at the time the measurement was performed.

As can be seen from table 3: when the magnesium element in the zinc alloy is measured, only aluminum and titanium have certain influence on the measurement of magnesium, and the influence of zinc on magnesium is mainly a matrix effect and can be eliminated by adding the zinc matrix element or establishing a working curve by adopting a zinc alloy standard sample. Therefore, the key to interference resolution is to reduce or eliminate the effect of aluminum and titanium on magnesium.

Interference cancellation

Based on the results of the previous discussion, since only aluminum and titanium interfere with magnesium in the determination of magnesium in zinc alloys, interference cancellation tests were performed on aluminum and titanium, respectively. Meanwhile, the experiment is considered to adopt hydrochloric acid to dissolve the sample, and then SrCl can be selected₂、LaCl₃Citric acid, ascorbic acid or 8-hydroxyquinoline as interference eliminator.

The elimination test of the aluminum element interference is carried out: 8 100mL volumetric flasks were prepared in advance, 1^#Volumetric flask with ultrapure water as calibration blank, 2^#～8^#5mL of 10mg/L magnesium standard solution is added into the volumetric flask, and the reaction is continued to 3^#～8^#5mL of 1000mg/L aluminum standard solution is added into the volumetric flask, and then 4^#～8^#The interference elimination agents (the addition amount is 5mL) with the corresponding numbers in the table 5 are sequentially added into the volumetric flask, the analysis is carried out after constant volume shaking up, and the measurement results are shown in the table 4.

TABLE 4 suppression of the degree of aluminum interference by various interference suppressants

As can be seen from table 4: adding LaCl to an aluminum-containing analysis solution₃、SrCl₂And 8-hydroxyquinoline, both significantly increase the absorbance of magnesium. And comparing the results with those of the analysis of magnesium single standard solution, LaCl₃And SrCl₂Substantially eliminates the interference of aluminum on magnesium, and 8-Hydroxyquinoline also greatly reduces the interference of aluminum.

The elimination test of titanium interference is carried out: 8 100mL volumetric flasks were prepared in advance, 1^#Volumetric flask with ultrapure water as calibration blank, 2^#～8^#5mL of 10mg/L magnesium standard solution is added into the volumetric flask, and the reaction is continued to 3^#～8^#Titanium standard solution with the concentration of 1mL and 1000mg/L is added into the volumetric flask, and then the volume is increased to 4^#～8^#The interference elimination agents (the addition amount is 5mL) with the corresponding numbers in the table 5 are sequentially added into the volumetric flask, the analysis is carried out after constant volume shaking up, and the measurement results are shown in the table 5.

TABLE 5 suppression of the degree of interference of different interference suppressants on titanium

As can be seen from table 5: adding LaCl into titanium-containing analysis solution₃Citric acid and ascorbic acid, all increase the absorbance of magnesium and substantially eliminate the interference of titanium with magnesium.

Based on the current state of development of zinc alloys, except for the fact that the wrought zinc alloys (such as Zn-Cu-0.1Ti) contain a small amount of titanium, the content of titanium in other forms of zinc alloys is very low, and as can be seen from Table 5, the interference of titanium with magnesium at a concentration of 1.0% is small, so the influence of titanium on the measurement of magnesium can be ignored in general, and only the interference of aluminum needs to be considered. Therefore, only the LaCl is considered to be selected when determining the magnesium element in the zinc alloy₃、SrCl₂Or 8-hydroxyquinoline as an interference eliminator to eliminate the interference of aluminum on magnesium.

Through the way, the method for determining the magnesium content in zinc and zinc alloy adopts LaCl₃、SrCl₂Or one of 8-hydroxyquinoline is used as an interference eliminator, so that the interference of aluminum on magnesium element in the light absorption value measurement can be greatly reduced; simple operation, low detection limit, high accuracy and wide linear range, and can meet the requirement of measuring magnesium in zinc and zinc alloy.