CN101556225A - Method adopting neutral salt electrolyte to electrolytically extract tiny impurities from steel - Google Patents

Abstract

The invention relates to a method for extracting fine inclusions in steel by electrolytically extracting neutral salt electrolyte, which belongs to the field of metal physics research methods. Specifically, sodium citrate, sodium chloride, ferrous sulfate and ammonium chloride are mixed in a certain proportion as a neutral electrolytic solution. After electrolysis, the undissolved matter is continuously reacted with ammonium chloride solution in a water bath, and the precipitated substance is dissolved repeatedly. Until the precipitation quality no longer changes, the obtained substance is the desired inclusion. Due to the use of neutral salt solution electrolysis, the fine inclusions obtained in the present invention have complete morphology and definite components under a scanning electron microscope, and micron-scale and nano-scale fine inclusions can be obtained.

Description

A method for electrolytic extraction of fine inclusions in steel using neutral salt electrolyte

technical field

The invention relates to a method for electrolytically extracting fine inclusions in steel by using a neutral salt electrolyte, and belongs to the field of metal physics research methods.

Background technique

The study of small inclusions in steel is of great significance for improving various important mechanical properties of steel materials. In order to better study the morphology and composition characteristics of its inclusions, so as to analyze their effects on the steel sample matrix, it is necessary to keep them intact Extracted from the steel sample without damage. The traditional method is often limited to the use of acidic or alkaline electrolytes, and its main disadvantages are: 1. The quality of the electrolyzed sample is large, the electrolysis time is long, and the cost is high; 2. The inclusions in the steel are easily soluble in acidic or alkaline environments 3. The size of the obtained inclusions is relatively large, which cannot meet the needs of current research work. Although some new technologies for electrolyzing inclusions have solved the above difficulties, the requirements for the electrolytic environment are relatively high, and the cost is generally high.

Contents of the invention

The purpose of the present invention is to provide a method for electrolytically extracting fine inclusions in steel by using neutral salt electrolyte. On the premise of low cost, remarkable effect and obtaining fine inclusions, it is necessary to study the formation mechanism of inclusions in steel and to It lays the foundation for the influence of various properties of steel and solves various practical problems related to production.

The method for extracting small inclusions in steel by electrolysis of neutral salt solution involved in the present invention is characterized in that it has the following steps:

1. Prepare a neutral salt electrolyte with a specific formula. The neutral electrolyte is compounded from chemical raw materials with the following weight ratios:

Sodium citrate: 0.05～0.5%

Sodium chloride: 0.1～5%

Ferrous sulfate: 1~5%

Ammonium chloride: 1-5%

The rest is deionized water;

2. The graphite electrode is used as the electrolysis cathode, and the steel sample containing inclusions is used as the anode. The steel sample is made into thin slices with a thickness of 1-2mm, the length and width of which can be placed in the electrolytic cell. Before electrolysis, the surface is cleaned with 3-5% dilute hydrochloric acid, and then ultrasonically cleaned with alcohol. When starting electrolysis, adjust the electrolysis potential to 3-10V, and the cathode current density to 0.02-0.1A/cm ² . Electrolyze until the anode sample is completely dissolved.

3. After the electrolyte is centrifuged with a centrifuge, the precipitate is added to a saturated ammonium salt (such as ammonium nitrate) solution and reacted in a water bath. Wet litmus paper was used to detect the evolution of ammonia gas from the reaction.

4. Repeat step 3 until no ammonia gas is released, that is, the wet litmus paper no longer turns blue. The precipitated matter is added to deionized water, centrifuged and clarified repeatedly in a centrifuge, and finally the fine inclusions precipitated are dried and stored for observation and characterization.

The steel inclusions involved in the present invention mainly include fine oxide, nitride, carbide, and sulfide inclusions.

In the neutral electrolyte used in the present invention, the effect of ammonium chloride is to react and dissolve the gray-green ferric hydroxide and ferrous hydroxide mixed precipitate obtained by electrolysis in an environment where heat is generated by electrolysis. Depending on the size of the steel sample, if the steel sample is small, the excess ferric hydroxide and ferrous hydroxide mixed precipitates will be completely dissolved by the ammonium chloride solution during the electrolysis process; if the steel sample is large, the ammonium chloride It is impossible to completely dissolve all the precipitates during the electrolysis process. The precipitated substances obtained after electrolysis need to be removed by a saturated ammonium salt (such as ammonium nitrate) solution in a water bath.

The mechanism of the present invention is: the substrate of the steel sample and the inclusions in the steel sample have different electrode decomposition potentials, the electrolysis potential is controlled between the two, and the steel substrate is continuously electrolyzed under the action of the current, while the inclusions remain in the electrolyte.

The main features of the present invention are: 1. The use of neutral salt electrolyte will not corrode and damage the fine inclusions easily soluble in acid or alkali; It is completely separated from the mixed precipitation of electrolytic ferric hydroxide and ferrous hydroxide, the reaction product is dissolved in water, and the neutral environment of the solution is always maintained, ensuring that the composition and shape of the inclusions are intact; 3. Using conventional electrochemical electrolysis The device is simple and easy to operate, and the cost is low, and the operation is simple and convenient in the laboratory environment.

Description of drawings

Fig. 1 is a schematic diagram of a conventional conventional electrolysis device used in the present invention.

Figure 2 shows Fe ₃ C inclusions obtained by electrolysis of X70 steel.

Figure 3 shows AlN inclusions obtained by electrolytic semi-process electrical steel.

Figure 4 shows the MoC inclusions in X80 steel obtained by electrolysis.

Detailed ways

Embodiment one: first configure electrolyte, formula is as follows: (wt%)

Sodium citrate: 0.2%, sodium chloride: 1%, ferrous sulfate: 3%, ammonium chloride: 2%, deionized water: 93.8%

Put the above electrolytic solution into the electrolytic cell, use the graphite electrode as the electrolysis cathode, and use the pipeline steel X70 steel sample containing inclusions as the anode. When starting electrolysis, adjust the electrolysis potential to 3-10V, and the cathode current density to 0.02-0.1A/cm ² . Electrolyze until the anode sample is completely dissolved.

After the solution obtained by electrolysis is centrifuged with a centrifuge, the precipitate is added to a saturated ammonium salt (such as ammonium nitrate) solution, reacted and dissolved in a water bath, and centrifuged and dissolved repeatedly until no ammonia gas is released. The precipitated matter is added to deionized water, and repeatedly centrifuged and clarified in a centrifuge, and finally the obtained fine inclusions are precipitated, dried and stored. And using scanning electron microscope to observe and analyze the composition, it is found that Fe ₃ C inclusions with a fine size in the nanometer scale are obtained, and the three-dimensional shape is good. as shown in picture 2.

Embodiment two: first configure electrolyte, formula is as follows: (wt%)

Sodium Citrate: 0.1%, Sodium Chloride: 4%, Ferrous Sulfate: 1%, Ammonium Chloride: 2%, Deionized Water: 92.9%

In this embodiment, the above electrolytic solution is put into an electrolytic cell, a graphite electrode is used as an electrolytic cathode, and a semi-process electrical steel sample containing inclusions is used as an anode. When starting electrolysis, adjust the electrolysis potential to 3-10V, and the cathode current density to 0.02-0.1A/cm ² . Electrolyze until the anode sample is completely dissolved.

After the solution obtained by electrolysis is centrifuged with a centrifuge, the precipitate is added to a saturated ammonium salt (such as ammonium nitrate) solution, reacted and dissolved in a water bath, and centrifuged and dissolved repeatedly until no ammonia gas is released. The precipitated matter is added to deionized water, centrifuged and clarified repeatedly in a centrifuge, and finally the fine inclusions precipitated are dried and stored for observation and characterization.

After scanning electron microscope observation and composition analysis, it was found that fine AlN inclusions with a size of a few microns were obtained, and the three-dimensional morphology was good. As shown in Figure 3.

Embodiment three: first configure electrolyte, formula is as follows: (wt%)

Sodium citrate: 0.4%, sodium chloride: 1%, ferrous sulfate: 4%, ammonium chloride: 5%, deionized water: 89.6%;

In this embodiment, the above-mentioned electrolyte solution is put into an electrolytic cell, a graphite electrode is used as an electrolysis cathode, and a pipeline steel X80 steel sample containing inclusions is used as an anode. When starting electrolysis, adjust the electrolysis potential to 3-10V, and the cathode current density to 0.02-0.1A/cm ² . Electrolyze until the anode sample is completely dissolved.

After the solution obtained by electrolysis is centrifuged with a centrifuge, the precipitate is added to a saturated ammonium salt (such as ammonium nitrate) solution, reacted and dissolved in a water bath, and centrifuged and dissolved repeatedly until no ammonia gas is released. The precipitated matter is added to deionized water, centrifuged and clarified repeatedly in a centrifuge, and finally the fine inclusions precipitated are dried and stored for observation and characterization.

After scanning electron microscope observation and composition analysis, it was found that fine MoC inclusions with a size of a few microns were obtained, and the three-dimensional morphology was good. As shown in Figure 4.

Claims (3)

1, a kind of method that adopts fine foreign matter in the neutral salt solution electroextraction steel is characterized in that having following step:

A. preparation has the neutral salt electrolytic solution of special formulation, and neutral electrolyte forms by the chemical raw material of following weight ratio is composite:

Sodium citrate: 0.05～0.5%

Sodium chloride: 0.1～5%

Ferrous sulphate: 1～5%

Ammonium chloride: 1～5%

All the other are deionized water;

B. with graphite electrode as electrolysis cathode, be anode with the steel sample that contains snotter; The steel sample is made the thin slice of the thick 1～2mm of being, and length and width are exceeded can put into electrolytic tank, with the watery hydrochloric acid clean surface of 3-5%, carries out ultrasonic cleaning with alcohol again before electrolysis; Adjusting electrolytic potential during the beginning electrolysis is 3～10V, and cathode-current density is 0.02～0.1A/cm ²Electrolysis is dissolved fully until the anode sample;

C. after using hydro-extractor centrifugal electrolytic solution, will precipitate in the adding ammonium nitrate solution, and in water-bath, react; Adopt moistening litmus paper detection reaction whether to emit ammonia;

D. repeat the c step, emit until no longer including ammonia, it is blue that promptly moistening litmus paper no longer becomes; Deposit is added deionized water, and centrifugal repeatedly on hydro-extractor, clarification, at last the fine foreign matter precipitation that obtains is dried, deposited, for observing, characterizing.

2, according to the described a kind of method that fine foreign matter extracts in the neutral salt electrolytic solution electroextraction steel that adopts of claim 1, it is characterized in that: include fine oxide, nitride, carbonide, sulphide inculsion in the snotter of described steel.

3, according to the described a kind of method that fine foreign matter extracts in the neutral salt electrolytic solution electroextraction steel that adopts of claim 1, it is characterized in that: the deposit that obtains after the electrolysis, adopt the ammonium nitrate solution water-bath to remove electrolysis remaining celadon ferric hydroxide, ferrous hydroxide mixed precipitation.

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