1. A method for rapidly judging the silicon content in an alloy is characterized by comprising the following steps:

1) respectively carrying out consistency pretreatment on a first alloy with known silicon content of m, a second alloy with known silicon content of n and an alloy to be detected aiming at the same type of alloy, and correspondingly preparing a first alloy detection solution, a second alloy detection solution and an alloy detection solution to be detected for analysis by a silicon-molybdenum-blue spectrophotometry; wherein m is more than n or m is less than n;

2) respectively detecting the absorbance of the first alloy detection solution, the second alloy detection solution and the alloy detection solution to be detected; and if the absorbance of the alloy detection solution to be detected is between the absorbance of the first alloy detection solution and the absorbance of the second alloy detection solution, judging that the silicon content of the alloy to be detected is between m and n.

2. The method for rapidly judging the silicon content in the alloy according to claim 1, wherein in the step 1), the alloy is a copper alloy; the consistency pretreatment comprises the following steps: dissolving copper alloy in acid, adding oxidant, boiling, cooling, mixing with ammonium molybdate, complexing agent and reducer, and developing.

3. The method for rapidly judging the silicon content in the alloy according to claim 2, wherein the acid is nitric acid, and the oxidizing agent is ammonium persulfate; 3-15ml of nitric acid is correspondingly added into every 0.01-0.05g of copper alloy, and the dosage of the corresponding ammonium persulfate is 0.2-2.3 g.

4. The method for rapidly judging the silicon content in the alloy as claimed in claim 2, wherein the complexing agent is oxalic acid, and the amount of oxalic acid is 0.25 to 1.25g per 0.01 to 0.05g of the copper alloy.

5. The method for rapidly judging the silicon content in the alloy according to claim 2, wherein the reducing agent is ammonium ferrous sulfate, and the amount of the ammonium ferrous sulfate is 1 to 3g per 0.01 to 0.05g of the copper alloy.

6. A method for the rapid determination of the silicon content in an alloy as claimed in any one of claims 2 to 5, characterized in that the amount of ammonium molybdate is 0.25 to 1.3g per 0.01 to 0.05g of copper alloy.

Background

In industrial alloys, the addition of a small amount of silicon as an alloying element can significantly improve the viscosity and fluidity of the alloy. The addition of a small amount of silicon to the copper alloy also improves the workability, mechanical properties and corrosion resistance. In the metal solder, a small amount of silicon is added to improve the performance of the solder to a certain extent. However, it is preferable that the amount of silicon is not increased as much as possible, and in actual industrial production, it is generally necessary to determine that the silicon content is within a certain acceptable range, and therefore, the content of silicon element needs to be measured.

At present, an inductively coupled plasma spectrometer can be used for measuring the silicon content in the copper alloy, but the method has high operation difficulty, needs professional chemical analyzers and is expensive in equipment.

GB/T5121.23-2008 method for measuring silicon content in copper and copper alloy proposes that silicon is measured by using silicon-molybdenum blue spectrophotometry, during the test, a sample is dissolved by nitric acid and is steamed to be thick slurry, hydrofluoric acid is added to dissolve insoluble silicon dioxide, and excessive fluorine ions are complexed by aluminum potassium sulfate. In the pH range of 1.0-1.5, silicon and ammonium molybdate generate silicomolybdic yellow heteropoly acid, the silicomolybdic yellow heteropoly acid is extracted by n-butyl alcohol in a sulfuric acid medium, organic phase is reduced to silicomolybdic blue by hydrazine sulfate and stannous chloride to obtain a solution to be detected, the absorbance of the solution to be detected is measured at the wavelength of 630nm of a spectrophotometer, and the content of silicon is calculated according to a working curve method. The method has long testing process, a standard working curve needs to be drawn each time, and the reagent consumption is high.

The Chinese patent application with application publication number CN105223146A discloses a method for measuring silicon content in ferro-silico-aluminum by adopting a silico-molybdenum blue colorimetric method, which is characterized in that after most of samples are dissolved by alkali liquor, then the rest of samples are dissolved by dilute hydrochloric acid and nitric acid, after the samples are completely dissolved by heating, an ammonium molybdate solution is added to generate silico-molybdenum yellow, an oxalic acid solution is added to mask interference elements, and an ammonium ferrous sulfate solution is added to generate silico-molybdenum blue; converting the content of the sample along with a standard sample with the same variety and similar content; the conversion formula is as follows:

the method simplifies the test operation to a certain extent; however, it is known that the detection result of the silicon-molybdenum blue color development method is greatly affected by environmental factors such as temperature and illumination, and even for the same sample, the detection results on different dates (or different time periods on the same date) are inconsistent, the formula method is an absorbance calculation result simulated according to experience, and uncertainties of different experimental conditions and summarized experience cause that the detection result obtained by the formula method can only be used as a reference, and cannot be used as a guide line for accurately evaluating the silicon content in the case of strict and accurate requirements on the silicon content.

Disclosure of Invention

The invention aims to provide a method for quickly judging the silicon content in an alloy, which solves the problems of long test flow and large reagent consumption of a working curve method; the formula method is dependent on experience, and the test accuracy is uncertain.

In order to achieve the purpose, the technical scheme of the method for rapidly judging the silicon content in the alloy is as follows:

a method for rapidly judging the silicon content in an alloy comprises the following steps:

1) respectively carrying out consistency pretreatment on a first alloy with known silicon content of m, a second alloy with known silicon content of n and an alloy to be detected aiming at the same type of alloy, and correspondingly preparing a first alloy detection solution, a second alloy detection solution and an alloy detection solution to be detected for analysis by a silicon-molybdenum-blue spectrophotometry; wherein m is more than n or m is less than n;

2) respectively detecting the absorbance of the first alloy detection solution, the second alloy detection solution and the alloy detection solution to be detected; and if the absorbance of the alloy detection solution to be detected is between the absorbance of the first alloy detection solution and the absorbance of the second alloy detection solution, judging that the silicon content of the alloy to be detected is between m and n.

The same type of alloy means that the base elements of the alloy are the same, such as copper alloy and the like.

The silicon-molybdenum blue spectrophotometry is to convert silicon into soluble silicic acid, add ammonium molybdate to react with silicic acid to generate silicon-molybdenum yellow, reduce the yellow to silicon-molybdenum blue by a reducing agent, and then measure the absorbance. For different alloy materials, the solution to be detected suitable for the silicon-molybdenum blue spectrophotometry can be prepared by referring to the related prior art.

The consistency pretreatment is a parallel and comparable pretreatment of the first alloy with the known silicon content of m, the second alloy with the known silicon content of n and the alloy to be detected, so that the absorbance of the obtained solution to be detected is mainly related to the silicon content.

According to the method for rapidly judging the silicon content in the alloy, the preparation of a silicon standard sample and the drawing process of a working curve in a traditional spectrophotometry are omitted, and whether the silicon content is in a certain specific qualified interval or not can be rapidly judged; the method has the advantages of greatly shortened operation process, reduced reagent consumption, reduced cost, simple operation, accurate result, and good stability.

The method eliminates errors of experimental conditions and empirical formulas due to parallel consistent pretreatment of different alloy samples, reflects the absorbance difference of real samples under the parallel contrast condition, and has extremely high reliability and accuracy of detection results, thereby creating precondition for more scientifically realizing the subsequent utilization or analysis of the alloy.

In the step 1), the alloy is a copper alloy; the consistency pretreatment comprises the following steps: dissolving copper alloy in acid, adding oxidant, boiling, cooling, mixing with ammonium molybdate, complexing agent and reducer, and developing. Compared with the determination method of GB/T5121.23-2008 determination method of silicon content in copper and copper alloy, the preparation process of the detection solution does not use highly corrosive hydrofluoric acid and does not need organic solvent extraction, and the preparation of the solution to be detected is more environment-friendly and convenient. In the step, the weighed alloy quality to be measured is consistent with the alloy quality with the known silicon content.

Preferably, the acid is nitric acid, and the oxidant is ammonium persulfate; 3-15ml of nitric acid is correspondingly added into every 0.01-0.05g of copper alloy, and the dosage of the corresponding ammonium persulfate is 0.2-2.3 g. Further preferably, the ammonium persulfate is added in the form of an ammonium persulfate solution, and the mass concentration of the ammonium persulfate solution is not less than 10%. The function of adding the oxidant and boiling is as follows: the little metasilicic acid generated by the dissolution of the alloy can be converted into orthosilicic acid more quickly and completely under the condition of boiling. If the conversion of the metasilicic acid is incomplete, the metasilicic acid does not form a complex with the ammonium molybdate, so that the detection result is low.

Preferably, the complexing agent is oxalic acid, and the dosage of the complexing agent is 0.25-1.25g corresponding to 0.01-0.05g of copper alloy. Further preferably, oxalic acid is added in the form of an oxalic acid solution in a mass concentration of not less than 5%.

Preferably, the reducing agent is ammonium ferrous sulfate, and the dosage of the reducing agent is 1-3g corresponding to 0.01-0.05g of copper alloy. Further preferably, the ammonium ferrous sulfate is added in the form of a solution, and the mass concentration of the solution is not less than 5%.

Preferably, the amount of ammonium molybdate is 0.25 to 1.3g per 0.01 to 0.05g of copper alloy. Further preferably, the ammonium molybdate is added in the form of an ammonium molybdate solution, and the mass concentration of the solution is not less than 5%.

Preferably, the silicon content of the alloy is not more than 1% by mass. More preferably, the silicon content in the alloy is 0.02 to 0.5% by mass.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following detailed description, but those skilled in the art will understand that the following described examples are some, not all, of the examples of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In the following examples, nitric acid, ammonium persulfate, ammonium molybdate, oxalic acid and ferrous ammonium sulfate were all analytical chemicals. Ammonium persulfate and water are used for preparing an ammonium persulfate solution with the mass concentration not less than 10%. Ammonium molybdate and water are used for preparing an ammonium molybdate solution with the mass concentration not less than 5%. Oxalic acid and water are used for preparing an oxalic acid solution with the mass concentration not less than 5%. Ammonium ferrous sulfate solution with mass concentration not less than 5% is prepared by using ammonium ferrous sulfate and water (ferrous ion hydrolysis is prevented, the ammonium ferrous sulfate solution is prepared under acidic condition, 0.5ml of concentrated sulfuric acid is added to every 100ml of water, and the ammonium ferrous sulfate is dissolved by using the water added with sulfuric acid).

The specific embodiment of the method for rapidly judging the silicon content in the alloy is as follows:

example 1

The method for rapidly judging the silicon content in the alloy comprises the following steps:

1) for copper alloys, the qualified interval of silicon content in the copper alloy is required to be [0.1 wt%, 0.2 wt% ]. 0.0200g of copper alloy to be measured, 0.0200g of copper alloy with known silicon content of 0.1 wt% and 0.0200g of copper alloy with known silicon content of 0.2 wt% are respectively weighed.

Respectively adding 5ml of nitric acid into the weighed samples, heating to dissolve the samples, then adding 2ml of 10% ammonium persulfate solution, and heating until the system boils; after cooling to room temperature (eliminating the influence of temperature on constant volume), 20ml of 5% ammonium molybdate solution, 20ml of 5% oxalic acid solution and 40ml of 5% ammonium ferrous sulfate solution are sequentially added, finally, the constant volume is set in a 100ml volumetric flask, and the color development is carried out for 20 min.

2) Respectively transferring the sample solutions into a cuvette, taking the solution without copper alloy as a blank control, and measuring the absorbance at 650 nm; blank control is step 1) without copper alloy added, other reagents were added normally.

3) Knowing that the absorbance value of the sample solution corresponding to the copper alloy with the silicon content of 0.1 wt% is M, knowing that the absorbance value of the sample solution corresponding to the copper alloy with the silicon content of 0.2 wt% is N, if the absorbance value of the sample solution of the copper alloy to be detected is between [ M, N ], the silicon content in the sample to be detected is qualified, and otherwise, the silicon content in the sample to be detected is unqualified.

In this embodiment, the absorbance values of the samples to be measured are shown in table 1, the absorbance value of the copper alloy with a silicon content of 0.1 wt% is 0.032Abs, and the absorbance value of the copper alloy with a silicon content of 0.2 wt% is 0.063 Abs. And comparing the absorbance value of the sample to be detected with the absorbance value of the copper alloy with known silicon content to determine whether the sample to be detected is qualified.

TABLE 1 Absorbance values of samples to be tested

Sample name

1#

2#

3#

4#

5#

0.1wt％

0.2wt％

Absorbance (Abs)

0.035

0.053

0.042

0.028

0.070

0.032

0.063

Test results

Qualified

Qualified

Qualified

Fail to be qualified

Fail to be qualified

Lower limit of

Upper limit of

Example 2

The method for rapidly judging the silicon content in the alloy comprises the following steps:

1) for copper alloys, the qualified interval of silicon content in the copper alloy is required to be [0.1 wt%, 0.3 wt% ]. 0.0300g of copper alloy to be measured, 0.0300g of copper alloy with known silicon content of 0.1 wt% and 0.0300g of copper alloy with known silicon content of 0.3 wt% are respectively weighed.

Respectively adding 5ml of nitric acid into the weighed samples, heating to dissolve the samples, then adding 2ml of 10% ammonium persulfate solution, and heating until the system boils; after cooling to room temperature, 20ml of 5% ammonium molybdate solution, 20ml of 5% oxalic acid solution and 40ml of 5% ammonium ferrous sulfate solution are added in sequence, finally the volume is fixed in a 100ml volumetric flask, and the color development is carried out for 20 min.

2) Respectively transferring the sample solutions into a cuvette, taking the solution without copper alloy as a blank control, and measuring the absorbance at 650 nm; blank control is step 1) without copper alloy added, other reagents were added normally.

3) And recording the absorbance value of the sample to be tested, wherein the absorbance value of the copper alloy with the silicon content of 0.1 wt% is 0.045Abs, and the absorbance value of the copper alloy with the silicon content of 0.3 wt% is 0.092 Abs. And comparing the absorbance value of the sample to be detected with the absorbance value of the copper alloy with known silicon content to determine whether the sample to be detected is qualified.

Example 3

The method for rapidly judging the silicon content in the alloy comprises the following steps:

1) for copper alloys, the qualified interval of silicon content in the copper alloy is required to be [0.05 wt%, 0.2 wt% ]. Respectively weighing 0.0100g of copper alloy to be measured, 0.0100g of copper alloy with known silicon content of 0.05 wt% and 0.0100g of copper alloy with known silicon content of 0.2 wt%.

Respectively adding 5ml of nitric acid into the weighed samples, heating to dissolve the samples, then adding 2ml of 10% ammonium persulfate solution, and heating until the system boils; after cooling to room temperature, 20ml of 5% ammonium molybdate solution, 20ml of 5% oxalic acid solution and 40ml of 5% ammonium ferrous sulfate solution are added in sequence, finally the volume is fixed in a 100ml volumetric flask, and the color development is carried out for 20 min.

2) Respectively transferring the sample solutions into a cuvette, taking the solution without copper alloy as a blank control, and measuring the absorbance at 650 nm; blank control is step 1) without copper alloy added, other reagents were added normally.

3) And recording the absorbance value of the sample to be tested, the absorbance value of the copper alloy with the silicon content of 0.05 wt% as 0.009Abs, and the absorbance value of the copper alloy with the silicon content of 0.2 wt% as 0.031 Abs. And comparing the absorbance value of the sample to be detected with the absorbance value of the copper alloy with known silicon content to determine whether the sample to be detected is qualified.

Example 4

The method for rapidly judging the silicon content in the alloy comprises the following steps:

1) for copper alloys, the qualified interval of silicon content in the copper alloy is required to be [0.05 wt%, 0.2 wt% ]. Respectively weighing 0.0100g of copper alloy to be measured, 0.0100g of copper alloy with known silicon content of 0.05 wt% and 0.0100g of copper alloy with known silicon content of 0.2 wt%.

Respectively adding 5ml of nitric acid into the weighed samples, heating to dissolve the samples, then adding 4ml of 10% ammonium persulfate solution, and heating until the system boils; after cooling to room temperature, 20ml of 5% ammonium molybdate solution, 20ml of 5% oxalic acid solution and 40ml of 5% ammonium ferrous sulfate solution are added in sequence, finally the volume is fixed in a 100ml volumetric flask, and the color development is carried out for 30 min.

2) Respectively transferring the sample solutions into a cuvette, taking the solution without copper alloy as a blank control, and measuring the absorbance at 650 nm; blank control is step 1) without copper alloy added, other reagents were added normally.

3) And recording the absorbance value of the sample to be tested, the absorbance value of the copper alloy with the silicon content of 0.05 wt% as 0.009Abs, and the absorbance value of the copper alloy with the silicon content of 0.2 wt% as 0.031 Abs. And comparing the absorbance value of the sample to be detected with the absorbance value of the copper alloy with known silicon content to determine whether the sample to be detected is qualified. In other embodiments of the method for rapidly determining the silicon content in the alloy, a detection solution for silicon-molybdenum blue spectrophotometry analysis can be prepared by a method in GB/T5121.23-2008 determination method of the silicon content in copper and copper alloy for copper alloy; in the process of preparing the corresponding detection solution, the dosage of the reagents such as ammonium persulfate, oxalic acid, ammonium ferrous sulfate and the like can be determined according to the action of the reagents, and generally speaking, the detection requirement of typical copper alloy can be met within the dosage range defined by the invention.

For example: based on example 4, 0.0500g of copper alloy was taken, 15ml of nitric acid was added, 2.3g of ammonium persulfate, 1.3g of ammonium molybdate, 1.25g of oxalic acid, and 3g of ferrous ammonium sulfate were added, and the same effect as in example 4 was obtained.

In example 4, 0.0100g of copper alloy, 3ml of nitric acid, 1.0g of ammonium persulfate, 0.25g of ammonium molybdate, 0.25g of oxalic acid, and 1g of ammonium ferrous sulfate were added to perform an experiment, and the same effect as in example 4 was obtained. (Note that the densities of a 10% ammonium persulfate solution, a 5% ammonium molybdate solution, a 5% oxalic acid solution, and a 5% ferrous ammonium sulfate solution can all be approximated as 1.0 g/ml.).