CN107607567B - A method for quantitative characterization of non-metallic inclusions in nickel-based superalloy powders - Google Patents

Abstract

The invention belongs to the technical field of metal physical chemistry, and discloses a quantitative characterization method for non-metallic inclusions in nickel-based superalloy powder. The nickel-based superalloy powder is taken, and the method of electron beam remelting is used to make a metal ingot with non-metallic inclusions gathered on the upper surface. Then, the part containing non-metallic inclusions is cut and acid-dissolved. Different elements and compounds are dissolved in acid step by step and separated by suction filtration. Finally, the non-metallic inclusions in the powder are filtered on the mixed cellulose microporous filter membrane, and the mixed cellulose microporous filter membrane is analyzed by scanning electron microscope. The non-metallic inclusions on the superalloy powder are subjected to morphology observation, composition confirmation and inclusion quantity statistics to achieve quantitative extraction of non-metallic inclusions in superalloy powders. The method of the invention has the advantages of easy access to equipment, simple operation, short time-consuming, high extraction rate, and unconstrained separation size.

Description

A method for quantitative characterization of non-metallic inclusions in nickel-based superalloy powders

technical field

The invention belongs to the technical field of metal physical chemistry, and in particular relates to a quantitative characterization method for non-metallic inclusions in nickel-based superalloy powders.

Background technique

Nickel-based superalloy powders refer to a series of superalloy powders prepared by argon or nitrogen atomization, which are mainly used in key components of aerospace engines. There are extremely high performance requirements for such materials. Even a small amount of non-metallic inclusions will have a serious impact on the physical and chemical properties of the final alloy parts. Strictly control the content of non-metallic inclusions in the alloy powder. It is an important condition for obtaining high-performance aerospace parts. Therefore, in order to accurately analyze the non-metallic inclusions in nickel-based superalloy powders, these inclusions should be extracted, and then their morphology, size distribution and quantity should be observed by scanning electron microscope, and their components should be analyzed by energy spectrum.

The non-metallic inclusions in the argon or nitrogen atomized superalloy powder mainly come from the shedding of the refractory materials of the crucible, the leaking bag and the nozzle of the master alloy smelting and pulverizing device, and the main inclusions are SiO ₂ , Al ₂ O ₃ and so on. However, the existing equipment conditions and milling technology cannot completely eliminate such inclusions.

At present, the methods for separating or extracting non-metallic inclusions in superalloys mainly include water elutriation, electrolysis, and electrostatic separation. The separation of non-metallic inclusions in superalloy powder by water elutriation method requires the calculation of the theoretical particle size and critical water flow velocity of graded elutriation. Interfering with sedimentation will lead to lower separation efficiency, and it is easy to cause incomplete separation of non-metallic inclusions, which requires high technical and experience of operators; electrolytic separation of non-metallic inclusions in superalloys often requires powder samples to be processed first. The operation is cumbersome, and the electrolysis time is long, reaching ten or even dozens of hours, which can only be used for a limited amount of small batteries. Electrolysis is performed on electrodes, and the amount of powder to prepare electrodes is limited, and it is difficult to objectively characterize the amount of inclusions contained in the powder. The electrolysis method has certain limitations in terms of the difficulty of the experiment and the accuracy of extraction; electrostatic separation method extracts high temperature For the non-metallic inclusions in the alloy, it is often necessary to control the appropriate corona electrode voltage and the rotational speed of the metal roller. There is an optimal separation size of the inclusions, and the separation rate cannot reach 100%. Due to the limitations of the above-mentioned existing methods, and the content of non-metallic inclusions in the powder itself is very low (there may only be 20 non-metallic inclusions below 100 μm in 1kg powder), the current method is difficult to be used as a high-purity nickel-based high temperature Accurate quantitative extraction of non-metallic inclusions in alloy powders.

SUMMARY OF THE INVENTION

In view of the above shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a quantitative characterization method for non-metallic inclusions in nickel-based superalloy powders.

The object of the present invention is achieved through the following technical solutions:

A method for quantitatively characterizing non-metallic inclusions in nickel-based superalloy powder, comprising the following steps:

(1) get nickel-based superalloy powder to ingot, and then adopt electron beam remelting to prepare alloy ingot, in the process of lowering ingot casting, non-melting non-metallic inclusions are floated and enriched on the upper surface of the ingot head;

(2) Using the method of wire cutting, cut the part containing non-metallic inclusions on the upper surface of the spindle head, grind the cut surface with sandpaper, and then add the cut part after cleaning and drying to the acid solution to dissolve, The non-metallic inclusions enriched on the upper surface of the ingot head are separated into an acid solution during the dissolution of the alloy surface to obtain a colloidal suspension acid solution;

(3) adding deionized water to the colloidal suspension acid obtained in step (2) to dilute, then adopting the mixed cellulose microporous membrane to carry out suction filtration, so that the colloidal suspension is attached to the mixed cellulose microporous membrane; Then, the mixed cellulose microporous filter membrane attached with the colloidal suspension is immersed in deionized water, and the colloidal suspension is desorbed into the deionized water by ultrasonic vibration to obtain a colloidal suspension;

(4) adding H ₂ O ₂ and oxalic acid to the colloidal suspension in step (3) to carry out a sufficient reaction, and after the reaction solution is diluted with deionized water, the mixed cellulose microporous membrane is used for suction filtration, so that the undissolved The residue is attached to the mixed cellulose microporous filter membrane; then the mixed cellulose microporous filter membrane attached with the residue is immersed in deionized water, and the residue is desorbed into the deionized water by ultrasonic vibration to obtain a residue mixture;

(5) adding HCl solution and HNO solution to the residue mixed solution of step ( ₄ ) to fully react, and after the reaction solution is diluted with deionized water, the mixed cellulose microporous membrane is used for suction filtration, so that the undissolved residual Then, the mixed cellulose microporous membrane with the residue attached is immersed in deionized water, and the residue is desorbed into deionized water by ultrasonic vibration;

(6) adding sufficient deionized water to the obtained solution in step (5), and adopting the mixed cellulose microporous filter membrane to carry out suction filtration to the solution, and placing the collected filter membrane in a drying oven to dry;

(7) Spray gold on the front side of the filter membrane obtained in step (6) (the side with the residue attached), use conductive glue to fix the edge in the orthogonal direction, and use a scanning electron microscope and an energy spectrometer to detect non-metallic inclusions on the filter membrane. The morphology and composition of the inclusions were characterized, and the number of non-metallic inclusion particles was counted.

The selection of the amount of nickel-based superalloy powder in step (1) can be freely and appropriately selected according to the amount of powder to be analyzed, which can more accurately quantitatively analyze the non-metallic inclusions that may exist in the powder.

The sanding in step (2) refers to sanding with No. 1200 sandpaper; the cleaning refers to ultrasonic cleaning in acetone solution and ethanol in sequence, and then rinsed with deionization.

Preferably, the acid solution described in step (2) refers to a mixed solution of concentrated HCl and concentrated HNO ₃ , wherein the mass fraction of concentrated HCl is 36-38%, and the mass fraction of concentrated HNO ₃ is 65-68%; The volume ratio of HCl to concentrated HNO ₃ is preferably 6:1.

Preferably, the pore size of the mixed cellulose microporous membrane in steps (3) to (6) is 0.22 μm, 0.45 μm or 0.8 μm.

Preferably, the frequency of the ultrasonic oscillation in steps (3) to (5) is 40 kHz and the power is 100 W.

Preferably, the HCl solution in step (5) refers to a HCl solution with a mass fraction of 20%, and the HNO ₃ solution refers to an HNO ₃ solution with a mass fraction of 65-68%.

The principle of the invention is as follows: in the production process of nickel-based superalloy powder, the refractory material of the crucible, leaking bag and nozzle of the master alloy smelting and pulverizing device falls off, and even the deoxidized product in the smelting process, the atomizing medium argon The solid particles in the gas and the environmental pollution of the process may introduce non-metallic inclusions, such as SiO ₂ , Al ₂ O ₃ and so on. The chemical composition of nickel-based superalloys mainly includes nickel, chromium, cobalt, tungsten, molybdenum, niobium, titanium, aluminum and other elements. Using the chemical properties of each alloying element, appropriate reagents are selected to promote the alloying elements to enter the solution in the form of ions. , which is separated from non-metallic inclusions such as SiO ₂ and Al ₂ O ₃ with relatively stable chemical properties, and finally achieves the purpose of extracting non-metallic inclusions. By controlling the ratio of _acid solution (the volume ratio of concentrated HCl and concentrated HNO solution is about 6: ₁ ), H2O2 and oxalic _acid , HCl solution and _HNO3 solution are added in turn to dissolve insoluble substances (such as W, Mo, Nb, Ti and their corresponding oxides), and the mixed cellulose microporous membrane was used for suction filtration to quantitatively characterize the number, composition and morphology of non-metallic inclusions in nickel-based superalloy powders.

The method of the present invention has the following advantages and beneficial effects:

(1) The present invention can analyze any amount of alloy powder, overcoming the deficiency of the limited sample size of the electrolysis method.

(2) Compared with the microporous filter membranes of other materials, the mixed cellulose microporous filter membrane adopted in the present invention has better hydrophilicity, and is mainly used for filtration of aqueous solutions. The materials are readily available and the cost is low. It also has the characteristics of uniform microporous structure, high porosity, no media shedding, fast filtration, minimal adsorption, and dilute acid resistance. During the ultrasonic oscillation process, the attachments on the surface of the filter membrane are easily detached without damaging the filter membrane, which greatly improves the extraction rate of non-metallic inclusions.

(3) The present invention adopts the combination of electron beam remelting and acid-dissolving method to extract non-metallic inclusions in nickel-based superalloy powder. Compared with the water elutriation method, the extraction rate is higher, and the non-metallic inclusions in the powder can be more accurately quantified. Inclusions.

(4) Compared with the electrolysis method, the present invention has the characteristics of simple operation, shorter time consumption and higher extraction rate, and can solve the limitation of using the electrolysis method to extract when the inclusion content is very small.

(5) Compared with the electrostatic separation method, the present invention has a higher extraction rate and is not restricted by the optimal size of non-metallic inclusions.

(6) Compared with the observation of non-metallic inclusions in the workpiece, the present invention overcomes the deficiency of incomplete observation of the workpiece.

(7) The present invention uses powder as the research object, only needs to simply press the powder into a block for electron beam remelting, no special processing and heat treatment are required, and the operation process is simple and easy to obtain.

Description of drawings

Fig. 1 is the alloy ingot whose upper surface is enriched with non-metallic inclusions in the embodiment of the present invention;

Fig. 2 is the alloy block containing inclusions on the upper surface after cutting and cleaning in the embodiment of the present invention;

3 is the dissolution and separation of the non-metallic inclusion-containing part and the alloy part in the acid dissolution process in the embodiment of the present invention;

4 is a schematic diagram of a suction filtration process in an embodiment of the present invention;

Fig. 5 is the mixed cellulose microporous filter membrane after suction filtration in the embodiment of the present invention;

FIG. 6 is the non-metallic inclusions on the filter membrane observed by scanning electron microscope in the embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

This example takes FGH96 nickel-based superalloy powder with a particle size of 105 μm or less as an example. The main elements of the alloy are: Cr, Co, W, Mo, Ti, Al, Nb and Ni. For quantitative extraction and characterization, the specific steps are as follows:

(1) Take about 270g of FGH96 nickel-based superalloy powder, press the powder into an ingot, and then use electron beam remelting to prepare an alloy powder ingot, and non-metallic inclusions float and enrich on the upper surface of the ingot head, see Figure 1;

(2) Using the method of wire cutting, cut the part containing the inclusions on the upper surface of the ingot, and sand the cut surface to 1200 grit sandpaper, and then ultrasonically clean the cut part in acetone solution for 10min, and ultrasonically use alcohol Wash for 10min, then rinse three times with deionized water, and blow dry for use, see Figure 2;

(3) Prepare 70mL acid solution, the acid solution is a mixture of concentrated HCl and concentrated HNO ₃ , the volume ratio is 6:1, wherein the mass fraction of the concentrated HCl solution is 36-38%, and the mass fraction of the concentrated HNO ₃ solution is about 65～68%;

(4) Put the sample treated in step (2) into the acid solution of step (3) at room temperature to undergo chemical reaction. After about 20 minutes, the inclusion-containing part has been dissolved and separated from the alloy part, as shown in Figure 3, the separation Then, take out the undissolved alloy block, and rinse the removed alloy block three times with deionized water in the direction of the beaker;

(5) in the colloidal suspension obtained in step (4), add 2L of deionized water to dilute; then adopt the mixed cellulose microporous filter membrane to carry out suction filtration to the obtained diluent, so that the colloidal suspension is attached to the mixed fibers On the cellulose microporous filter membrane, the pore size of the mixed cellulose microporous filter membrane is 0.8 μm;

(6) The mixed cellulose microporous filter membrane with the colloidal suspension attached in step (5) was placed in a beaker containing 20 mL of deionized water, and ultrasonically oscillated for 10 min to obtain a colloidal suspension, and gently used tweezers. Take out the filter membrane from the beaker, and rinse the filter membrane three times with deionized water in the direction of the beaker, the ultrasonic frequency is 40kHz, and the power is 100W;

(7) To the colloidal suspension obtained in step (6), add 300 mL of 30wt.% H ₂ O ₂ solution, then add 20 g of oxalic acid crystals, fully stir until the oxalic acid crystals are completely dissolved, the solution turns yellow, and the suspension Begin to become clear, there are obvious residues at the bottom of the beaker, this process lasts for about 30min, and finally 500Ml deionized water is added for dilution;

(8) The solution obtained in the step (7) is subjected to suction filtration by using a mixed cellulose microporous filter membrane, the collected filter membrane is placed in a beaker containing 20 mL of deionized water, and ultrasonically oscillated for 10 min to obtain a residue mixture , gently remove the filter membrane from the beaker with tweezers, and rinse the filter membrane 3 times with deionized water toward the beaker;

(9) Add 100mL 20wt.% HCl solution to the residue mixture in step ( ₈ ), stir well, then add 30mL 65wt.% HNO solution, stir well until the residue is dissolved, the solution clarity is higher, add 500mL Dilute with deionized water; then use mixed cellulose microporous filter membrane to perform suction filtration on the obtained clarified solution, place the collected filter membrane in a beaker containing 20 mL of deionized water, oscillate ultrasonically for 10 min, and gently use tweezers. Remove the filter membrane from the beaker and rinse the filter membrane three times with deionized water toward the beaker;

(10) Add 500 mL of deionized water to the solution obtained in step (9), and use the mixed cellulose microporous filter membrane to perform suction filtration on the solution. The suction filtration process is shown in Figure 4, and the filter membrane is shown in Figure 5. The filter membrane is placed in a drying oven to dry;

(11) The front surface of the filter membrane obtained in step (10) is sprayed with gold, and the edge in the orthogonal direction is fixed with conductive glue. Characterization, the results are shown in Figure 6 and Table 1, and the number of non-metallic inclusion particles is counted.

Table 1

element Quality Score/% Atomic Percent/% O 59.26 71.86 Si 40.74 28.14 total 100.00 100.00

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (5)

1. A quantitative characterization method for nonmetallic inclusions in nickel-based superalloy powder is characterized by comprising the following steps:

(1) taking nickel-based high-temperature alloy powder for ingot pressing, then adopting electron beam remelting to prepare an alloy ingot, and floating up and enriching non-molten non-metallic inclusion to the upper surface of an ingot head in the downward ingot casting process;

(2) cutting off the part containing the nonmetallic inclusion on the upper surface of the ingot head by adopting a linear cutting mode, polishing the cutting surface of the ingot head by using abrasive paper, then washing and drying the cut off part, adding the part into acid liquor for dissolving, and separating the nonmetallic inclusion enriched to the upper surface of the ingot head into the acid liquor in the process of dissolving the alloy surface to obtain colloidal suspension acid liquor;

(3) adding deionized water into the colloidal suspended acid solution obtained in the step (2) for dilution, and then performing suction filtration by adopting a mixed cellulose microporous filter membrane to attach the colloidal suspended substance to the mixed cellulose microporous filter membrane; then immersing the mixed cellulose microporous filter membrane attached with the colloidal suspended matters into deionized water, and desorbing the colloidal suspended matters into the deionized water by ultrasonic oscillation to obtain colloidal suspension;

(4) adding into the colloidal suspension of the step (3)Addition of H ₂ O ₂ Fully reacting with oxalic acid, diluting the reaction solution with deionized water, and performing suction filtration by using a mixed cellulose microfiltration membrane to attach undissolved residues to the mixed cellulose microfiltration membrane; then immersing the mixed cellulose microporous filter membrane attached with the residues into deionized water, and desorbing the residues into the deionized water by ultrasonic oscillation to obtain a residue mixed solution;

(5) adding HCl solution and HNO into the residue mixed solution in the step (4) ₃ Fully reacting the solution, diluting the reaction solution by deionized water, and performing suction filtration by using a mixed cellulose microporous filter membrane to attach undissolved residues to the mixed cellulose microporous filter membrane; then immersing the mixed cellulose microporous filter membrane attached with the residues into deionized water, and performing ultrasonic oscillation to desorb the residues into the deionized water;

(6) adding enough deionized water into the solution obtained in the step (5), performing suction filtration on the solution by adopting a mixed cellulose microporous filter membrane, and placing the collected filter membrane in a drying box for drying;

(7) performing gold spraying treatment on the front surface of the filter membrane obtained in the step (6), fixing the edges in the orthogonal direction by using conductive adhesive, representing the appearance and components of the nonmetallic inclusion on the filter membrane by using a scanning electron microscope and an energy spectrometer, and counting the number of particles of the nonmetallic inclusion;

the acid liquor in the step (2) refers to concentrated HCl and concentrated HNO ₃ The mixed solution of (2), wherein the mass fraction of the concentrated HCl is 36-38%, and the concentrated HNO is ₃ The mass fraction of (A) is 65-68%;

the concentrated HCl and the concentrated HNO in the step (2) ₃ The volume ratio of (A) to (B) is 6: 1; the HCl solution in the step (5) is a 20% HCl solution in mass fraction.

2. The method of claim 1, wherein the method comprises the steps of: the abrasive paper polishing in the step (2) is to polish with No. 1200 abrasive paper; the cleaning is ultrasonic cleaning in acetone solution and ethanol in sequence, and then washing with deionized water.

3. The method of claim 1, wherein the method comprises the steps of: the aperture of the mixed cellulose microporous filter membrane in the steps (3) to (6) is 0.22 μm, 0.45 μm or 0.8 μm.

4. The method of claim 1 for quantitative characterization of non-metallic inclusions in a nickel-base superalloy powder, wherein the method comprises: in the steps (3) to (5), the frequency of the ultrasonic oscillation is 40kHz, and the power is 100W.

5. The method of claim 1 for quantitative characterization of non-metallic inclusions in a nickel-base superalloy powder, wherein the method comprises: the HNO in the step (5) ₃ The solution is HNO with the mass fraction of 65-68% ₃ And (3) solution.

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