Method for evaluating the cleanliness of recycled alclad aluminum melt

Abstract

The application discloses a kind of evaluation methods of regenerating aircraft aluminum melt cleanliness, belong to the field of secondary metals.The method is after regenerating aircraft aluminum melt is gas removed and impurity by Spinning Nozzle Inert Gas Floatation (SNIF), filtered by Ceramic Foam Filter (CFF), evaluate regenerating aircraft aluminum melt cleanliness Q.Melt cleanliness detection includes: Liquid Metal Cleanliness Analyzer (LIMCA) detects the number of inclusion particle size ≥20 μm and ≥40 μm, respectively, N 20 And N 40 (Individual / kgAl);Porous Disc Filtration Analysis (PoDFA) detects inclusion area P S (mm 2 / kgAl) of particle size ≥1 μm;Alscan detects hydrogen content H A (ml / 100gAl);Regulate regenerating aircraft aluminum melt cleanliness Q as dimensionless value.The application objectively and comprehensively evaluates the cleanliness of regenerating aircraft aluminum melt, with the characteristics of simple evaluation steps, easy to obtain evaluation parameters, high accuracy and wide application range.

Description

Technical Field

[0001] This invention belongs to the field of recycled metals, and specifically relates to a method for evaluating the cleanliness of recycled aerospace aluminum melt. Background Technology

[0002] Recycled aluminum offers advantages such as energy conservation, emission reduction, and low cost. Deep purification of the melt is one of the most critical technologies and processes in recycled aluminum production. Current methods for evaluating melt cleanliness generally use metallographic analysis to assess ingot cleanliness, which is an indirect approach and cannot comprehensively and objectively reflect the melt cleanliness. Because the cleanliness requirements for recycled aerospace aluminum melt are extremely stringent, existing methods cannot meet these requirements. Therefore, a new method for evaluating the cleanliness of recycled aerospace aluminum melt is urgently needed.

[0003] Chinese invention patent (CN114391100A) discloses a method for evaluating the cleanliness of steel. This invention provides a method for evaluating the cleanliness of steel based on ultrasonic testing, which can rapidly obtain highly reliable data. Ultrasonic testing is performed on at least a portion of a radial area ranging from 90% to 100% of the steel, with the center of the steel set to 0% and the surface to 100%. The cleanliness is evaluated based on the size and number of inclusions in the steel obtained through ultrasonic testing. This invention evaluates the cleanliness of steel after casting; therefore, it cannot evaluate the cleanliness of the melt or the cleanliness of recycled aerospace aluminum melt.

[0004] Chinese invention patent (CN115631164A) discloses a method for evaluating the level of in-furnace refining process for molten aluminum. The method includes sampling after in-furnace refining, metallographic microscopic inspection, analysis of the metallographic images using ImageJ software to calculate the slag removal rate, evaluation of the level of a single in-furnace refining process based on the slag removal rate, and evaluation of the overall level of in-furnace refining process based on the rating of a single in-furnace refining process. This invention accurately calculates the slag removal rate of a single in-furnace refining process using metallographic microscopy and ImageJ software. Based on the slag removal rate, it establishes a data standard for graded evaluation of the in-furnace refining process, providing a detailed description of the required level of molten aluminum refining processes for various products, especially in continuous casting and rolling production. It provides quantitative reference data for production technicians, which can be used for product production plan design and for identifying the causes of product defects. However, this invention uses metallographic methods to determine the slag removal amount after in-furnace sampling, which cannot determine the slag content and hydrogen content per unit mass of melt. Therefore, this invention cannot meet the evaluation requirements for the cleanliness of recycled aerospace aluminum melt.

[0005] Chinese invention patent (CN109182818A) discloses a method for slag removal and purification in aluminum alloy ingot smelting. The method includes the following steps: degreasing, alkaline etching, and acid washing of the aluminum alloy ingot to obtain a pretreated aluminum alloy ingot; then adding the aluminum alloy to a furnace and heating and melting it into a melt; filtering to remove impurities; raising the furnace temperature to 710–725°C and controlling the temperature to be stable; simultaneously introducing a mixture of nitrogen and chlorine gas and a refining agent into the aluminum alloy melt to remove floating slag from the surface of the melt; after standing for a period of time, filtering to remove particulate impurities; and detecting inclusions in the aluminum alloy using the PoDFA method. This invention, by incorporating the PoDFA method, can not only detect the quantity of inclusions but also determine their type, allowing for targeted adjustments to the melt treatment method. Producers can use the PoDFA measurement results to determine whether the molten aluminum can be used to produce products with strict requirements for inclusion content. This invention only uses PoDFA for semi-quantitative analysis of inclusions in the melt, without detecting hydrogen content, and therefore cannot objectively and comprehensively reflect the cleanliness of the melt. Thus, this invention cannot meet the evaluation requirements for the cleanliness of recycled aerospace aluminum melt.

[0006] Chinese invention patent (CN101398363A) discloses a pneumatic aluminum melt inclusion detection device and method. This invention consists of three parts: a pneumatic system, a temperature control system, and a filtration and weighing system. The pneumatic system is located outside the temperature control system, providing a stable pressure difference for the filtration and weighing system. The temperature control system is inside the pneumatic system, and the filtration and weighing system is outside the filtration section, ensuring temperature stability during the filtration process. The filtration and weighing system mainly consists of two parts: the filtration section is located inside the temperature control system, and the weighing section is placed directly below the filtration section. The filtration and weighing system completes the filtration of aluminum melt to remove inclusions and measures and saves the weight of the filtered aluminum melt in real time. This invention provides a semi-quantitative detection method for aluminum melt slag content. After filtration with molten foam ceramics, the cleanliness of the melt is evaluated by measuring the weight of the filtered aluminum melt, but this cannot reflect the quantity of inclusions per unit mass and the hydrogen content. Therefore, this invention cannot meet the evaluation requirements for the cleanliness of recycled aerospace aluminum melt.

[0007] In summary, existing methods for evaluating melt cleanliness primarily focus on semi-quantitative or qualitative assessments of inclusions, failing to accurately reflect the quantity and size of inclusions and hydrogen content within the melt. There is no comprehensive and systematic method for detecting and evaluating melt cleanliness. Therefore, a method for evaluating the cleanliness of recycled aerospace aluminum melt is urgently needed. Summary of the Invention

[0008] To systematically and effectively evaluate the cleanliness of recycled aerospace aluminum melt, this invention discloses a method for evaluating the cleanliness of recycled aerospace aluminum melt. This method evaluates the cleanliness Q of recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration. The melt cleanliness detection includes: LiMCA method for detecting slag content, and detecting the number of inclusions with particle sizes ≥20 μm and ≥40 μm, denoted as N respectively. 20 and N 40 (particles / kgAl); PoDFA detection of inclusion area P with particle size ≥1μm S (mm 2 / kgAl); Alscan method for detecting hydrogen content H A (ml / 100gAl). Specified cleanliness of recycled aerospace aluminum melt. Q is a dimensionless numerical value. This invention objectively, comprehensively, and quantitatively evaluates the cleanliness of recycled aerospace aluminum melt, and features simple evaluation steps, readily available evaluation parameters, reliable results, and wide applicability.

[0009] To address the problems of the existing technology, the present invention provides the following technical solution:

[0010] A method for evaluating the cleanliness of recycled aerospace aluminum melt, characterized in that the method evaluates the cleanliness Q of the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration. Melt cleanliness testing includes: LiMCA method to detect the number of inclusions with particle sizes ≥20 μm and ≥40 μm, denoted as N respectively. 20 and N 40 (particles / kgAl); PoDFA method for detecting the area P of inclusions with a particle size ≥1μm S (mm 2 / kgAl); Alscan method for detecting hydrogen content H A (ml / 100gAl). Specified cleanliness of recycled aerospace aluminum melt. Q is a dimensionless numerical value.

[0011] Furthermore, the LiMCA detection time for the regenerated aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration is 40.0-80.0 s.

[0012] The detection time is related to the melt volume. A smaller melt volume results in a higher proportion of melt detected by the probe per unit time, leading to a shorter detection time; conversely, a larger melt volume results in a longer detection time. Experiments have shown that the LiMCA method, with a detection time of 40.0-80.0 s, can cover the detection time required for most melts.

[0013] Furthermore, after the recycled aerospace aluminum melt has undergone SNIF degassing and impurity removal and CFF filtration, 5.0-15.0 cm of scum is removed from the surface, and then 1.0-5.0 kg of samples are taken for PoDFA testing.

[0014] The thickness of the scum in recycled aerospace aluminum melt is related to the impurity content of the raw materials. Higher impurity content results in a larger amount and thickness of scum, while lower impurity content leads to a thinner scum. Practical experience shows that the thickness of the scum in recycled aerospace aluminum melt is between 5.0 and 15.0 cm.

[0015] The mass of the test sample is related to the melt volume. A smaller melt volume requires fewer sampling points and results in a smaller sample mass; conversely, a larger melt volume requires more sampling points and results in a larger sample mass. Practice has shown that a PoDFA sample size of 1.0-5.0 kg can meet all testing requirements.

[0016] Furthermore, PoDFA detected inclusions including Al2O3, MgO, CaO, SiO2, MgAl2O4, ZnO, TiB2, TiC, Al4C3, and P. S This represents the total content of inclusions.

[0017] Furthermore, the Alscan detection time for the regenerated aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration is 1.0-10.0 min.

[0018] The detection time is related to the melt volume. A smaller melt volume results in a higher proportion of melt being detected by the probe per unit time, leading to a shorter detection time; conversely, a larger melt volume results in a longer detection time. Experiments have shown that the Alscan method, with a detection time of 1.0-10.0 s, can cover the detection time required for most melts.

[0019] Furthermore, the characteristic is that the regenerated aerospace aluminum melt, after SNIF degassing and impurity removal and CFF filtration, contains N 20 >1000 particles / kgAl, or N 40 >200 per kg Al, or P S >0.015mm 2 / kgAl, or H A If the concentration is >0.15ml / 100gAl, repeat the SNIF degassing and impurity removal process and CFF filtration. The parameter settings are based on the requirements of aerospace aluminum alloy for melt cleanliness.

[0020] Furthermore, the characteristic is that the regenerated aerospace aluminum melt, after SNIF degassing and impurity removal and CFF filtration, contains N 20 ≤1000 particles / kgAl, N 40 ≤200 particles / kg Al, P S ≤0.015mm 2 / kgAl、H A ≤0.15ml / 100gAl, calculate the dimensionless

[0021] Furthermore, after SNIF degassing and impurity removal and CFF filtration, the regenerated aerospace aluminum melt with a Q≤25 is considered a qualified ultra-clean regenerated aerospace aluminum melt; if Q>25, SNIF degassing and impurity removal and CFF filtration are repeated; through big data analysis of the cleanliness data of the regenerated aerospace aluminum melt, it was found that Q of 25 is the critical value for qualified aerospace aluminum.

[0022] This invention overcomes the shortcomings of existing technologies and discloses a method for evaluating the cleanliness of recycled aerospace aluminum melt. After SNIF degassing and impurity removal and CFF filtration, the cleanliness of the recycled aerospace aluminum melt is determined using the LiMCA method to detect the number of inclusions with particle sizes ≥20μm and ≥40μm; the PoDFA method to detect the area of ​​inclusions with particle sizes ≥1μm; and the Alscan method to detect the hydrogen content. Q is a dimensionless numerical value. This invention enables an objective, accurate, and reliable evaluation of the cleanliness of recycled aerospace aluminum melt, featuring simple evaluation steps, readily available evaluation parameters, high accuracy, and wide applicability.

[0023] The principle of this invention is as follows:

[0024] (1) Principle of LiMCA method for slag determination

[0025] The LiMCA detection device's sensor consists of a sealed, insulated sampling tube, micropores on the tube's sidewall, and electrodes inside and outside the tube. Based on the principles of gas dynamics, applying a pressure difference across the sampling tube allows for the introduction or removal of the analyte. A constant direct current is passed between the two electrodes, and the potential difference is concentrated only in the micropore channel and its vicinity; this area is called the electrosensitive zone, hence the method is also known as the electrosensitive zone method. When a non-metallic inclusion passes through the electrosensitive zone with the analyte, the resistance between the two electrodes changes. This "event" of the inclusion passing through the electrosensitive zone manifests as a voltage pulse signal. The magnitude of this pulse signal indicates the size of the inclusion, and the number of pulse signals indicates the number of inclusions.

[0026] (2) Principle of PoDFA method for slag determination

[0027] The molten metal is vacuum filtered using a micron-sized ceramic filter plate. As the molten metal passes through the filter, inclusions are trapped on it. After solidification, the sample is prepared using precision cutting and polishing equipment. Metallographic analysis is used to characterize the area of ​​the inclusions, and the area-to-weight ratio is calculated based on the mass of the filtered molten metal to perform qualitative and quantitative inclusion analysis.

[0028] (3) Principle of LiMCA and PoDFA method for synergistic evaluation of melt slag content

[0029] This invention utilizes the LiMCA and PoDFA methods to synergistically detect the slag content in recycled aerospace aluminum melt, aiming to more objectively and accurately reflect the slag content information. While the LiMCA method can quantitatively detect the size and quantity of inclusions in recycled aerospace aluminum melt, it cannot detect the content of inclusions with a particle size <20μm, nor can it obtain the type and distribution of inclusions. The PoDFA method can detect the area of ​​inclusions with a particle size ≥1μm and obtain information on the type and distribution of inclusions; however, it cannot determine the specific numerical value of inclusion content. Therefore, this invention employs the LiMCA and PoDFA methods synergistically to evaluate the slag content in recycled aerospace aluminum melt, ensuring that the results include both quantitative information on the slag content and the slag composition and distribution. This achieves the goal of comprehensively, objectively, and truthfully reflecting the slag content in recycled aerospace aluminum melt, meeting the extremely high requirements for melt cleanliness in aerospace aluminum alloys.

[0030] (4) Principle of hydrogen determination by Alscan method

[0031] Alscan employs a closed-loop circulation method to directly detect the hydrogen content in molten aluminum. A small amount of working gas (nitrogen or argon) is introduced into an immersion probe, contacting the molten aluminum. This gas circulates continuously in a closed loop until the hydrogen content and pressure in the molten aluminum reach equilibrium. The concentration of H2 in the gas is detected and converted into the hydrogen content in the molten aluminum, which is then displayed. This method is rapid, repeatable, and highly accurate. The hydrogen content in the closed-loop gas is detected by a unique thermal sensor, ensuring high repeatability and a wide detection range. The built-in microprocessor of the hydrogen analyzer directly processes and obtains the hydrogen content data.

[0032] (5) The invention is creatively proposed The evaluation parameters comprehensively consider four dimensions: inclusions in the recycled aerospace aluminum melt (including inclusion size, quantity, and distribution) and hydrogen content, totaling N. 20 N 40 P S H A It uses five evaluation indicators (Q5, Q6, Q7, Q8, Q9) to objectively, comprehensively, and accurately reflect the purity of recycled aerospace aluminum melt compared to existing melt purity evaluation methods.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) Comprehensive and objective cleanliness evaluation. This invention uses the LiMCA method and the PoDFA method to detect the slag content of the recycled aerospace aluminum melt, and uses the Alscan method to detect the hydrogen content of the recycled aerospace aluminum melt online. The detection methods are comprehensive, and the results cover all indicators of melt cleanliness, so as to achieve a comprehensive and objective evaluation of the cleanliness of the recycled aerospace aluminum melt.

[0035] (2) Evaluation parameters are easy to obtain. The LiMCA, PoDFA and Alscan detection methods used in this invention are all mature and usable methods for detecting melt cleanliness. The data are easy to obtain and the evaluation methods are highly versatile.

[0036] (3) High evaluation accuracy. The present invention specifies that the cleanliness level Q is used to objectively and quantitatively evaluate the content of slag and hydrogen content in recycled aerospace aluminum melt, and the evaluation results are highly accurate.

[0037] (4) The melt purity evaluation method of the present invention has greatly improved the qualification rate of recycled aerospace aluminum products, reduced product costs, significantly improved product quality, and improved the industrialization technology level of recycled aerospace aluminum.

[0038] (5) The evaluation steps of this invention are simple, the evaluation parameters are easy to obtain, and the scope of application is wide. It has the advantages of simple process, objective and true results, high accuracy and easy industrialization. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a process flow diagram of a method for evaluating the cleanliness of recycled aerospace aluminum melt according to the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] Conversely, this invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims. Furthermore, to provide a better understanding of the invention, certain specific details are described in detail below. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0043] The implementation of the present invention will be described in detail below with reference to specific embodiments:

[0044] Example 1

[0045] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 40.0 s. 20The number of inclusions N with a particle size ≥40μm is 975 per kg Al. 40 The concentration was 10⁵ particles / kg Al; after removing 5.0 cm of residue, a 1.0 kg sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.006mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 1.0 min. A It is 0.040 ml / 100 g Al. N 20 N 40 P S and H A All four indicators are qualified, then proceed as follows: The calculated value of Q = 16.075 ≤ 25 indicates that the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration is qualified ultra-clean recycled aerospace aluminum melt.

[0046] Example 2

[0047] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 42.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1250 per kg Al. 40 The concentration was 145 particles / kgAl; after removing 5.5cm of residue, a 1.2kg sample was taken and the area of ​​inclusions with a particle size ≥1μm was determined by the PoDFA method. S It is 0.011mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 1.5 min. A It is 0.083 ml / 100g Al. N 20 If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0048] Example 3

[0049] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 44.0 s. 20 The number of inclusions N with a particle size ≥40μm is 980 per kg Al. 40 The concentration was 215 particles / kgAl; after removing 6.0 cm of residue, a 1.4 kg sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.008mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 2.0 min. A It is 0.095 ml / 100g Al. N 40 If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0050] Example 4

[0051] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 46.0 s. 20 The number of inclusions N with a particle size ≥40μm is 935 per kg Al. 40 The concentration was 135 particles / kg Al; after removing 6.5cm of residue, a 1.6kg sample was taken and the area of ​​inclusions with a particle size ≥1μm was determined by the PoDFA method. S It is 0.017mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 2.5 min. A It is 0.102 ml / 100 g Al. P S If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0052] Example 5

[0053] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 48.0 s. 20 The number of inclusions N with a particle size ≥40μm is 955 per kg Al. 40 The concentration was 145 particles / kgAl; after removing 7.0 cm of residue, 1.8 kg of sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.009mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 3.0 min. A It is 0.168 ml / 100g Al. H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N...20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0054] Example 6

[0055] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 50.0 s. 20 The number of inclusions N with a particle size ≥40μm is 930 / kgAl. 40 The sample size was 100 particles / kg Al; after removing 7.5cm of residue, a 2.0kg sample was taken. The area of ​​inclusions with a particle size ≥1μm was determined by the PoDFA method. S It is 0.010mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 3.0 min. A It is 0.050 ml / 100 g Al. N 20 N 40 P S and H A All four indicators are qualified, then proceed as follows: The calculation yielded Q = 16.930 ≤ 25, indicating that the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration was qualified as ultra-clean recycled aerospace aluminum melt.

[0056] Example 7

[0057] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 52.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1300 / kgAl. 40 The concentration was 235 particles / kgAl; after removing 8.0 cm of residue, 2.2 kg of sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.012mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 3.5 min. A It is 0.112 ml / 100g Al. N 20 and N 40 If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0058] Example 8

[0059] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 54.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1450 / kgAl. 40 The sample size was 180 particles / kgAl; after removing 8.5cm of residue, 2.4kg of sample was taken and the area of ​​inclusions with a particle size ≥1μm was determined by PoDFA method. S It is 0.018mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 4.0 min. A It is 0.073 ml / 100g Al. N 20 and P S If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0060] Example 9

[0061] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 56.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1150 / kgAl. 40 The concentration was 145 particles / kg Al; after removing 9.0 cm of residue, a 2.6 kg sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.014mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 4.5 min. A It is 0.184 ml / 100g Al. N 20 and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0062] Example 10

[0063] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 58.0 s. 20The number of inclusions N with a particle size ≥40μm is 900 / kgAl. 40 The sample size was 100 particles / kg Al; after removing 9.5 cm of residue, 2.8 kg of sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.010mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 5.0 min. A It is 0.100 ml / 100 g Al. N 20 N 40 P S and H A All four indicators are qualified, then proceed as follows: The calculation yielded Q = 21.900 ≤ 25, indicating that the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration was qualified as ultra-clean recycled aerospace aluminum melt.

[0064] Example 11

[0065] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 60.0 s. 20 The number of inclusions N with a particle size ≥40μm is 875 per kg Al. 40 The sample size was 245 particles / kgAl; after removing 10.0 cm of residue, a 3.0 kg sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.020mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 5.5 min. A It is 0.103 ml / 100g Al. N 40 and P S If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0066] Example 12

[0067] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 62.0 s. 20 The number of inclusions N with a particle size ≥40μm is 935 per kg Al. 40 The sample size was 230 particles / kgAl; after removing 10.5cm of residue, 3.2kg of sample was taken and the area of ​​inclusions with a particle size ≥1μm was determined by PoDFA method. S It is 0.013mm2 / kgAl; the hydrogen content H was obtained by Alscan method after 6.0 min. A It is 0.196 ml / 100g Al. N 40 and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0068] Example 13

[0069] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 64.0 s. 20 The number of inclusions N with a particle size ≥40μm is 895 per kg Al. 40 The sample size was 160 particles / kg Al; after removing 11.0 cm of residue, a 3.4 kg sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.019mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 6.5 min. A It is 0.201 ml / 100 g Al. P S and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0070] Example 14

[0071] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 66.0 s. 20 The number of inclusions N is 800 per kg Al with a particle size ≥ 40 μm. 40 The concentration was 110 particles / kg Al; after removing 11.5 cm of residue, a 3.6 kg sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by the PoDFA method. S It is 0.008mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 6.5 min. A It is 0.050 ml / 100 g Al. N 20 N40 P S and H A All four indicators are qualified, then proceed as follows: The calculation yielded Q = 17.600 ≤ 25, indicating that the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration was qualified as ultra-clean recycled aerospace aluminum melt.

[0072] Example 15

[0073] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 68.0 s. 20 The number of inclusions N with a particle size ≥40μm is 795 per kg Al. 40 The sample size was 255 particles / kgAl; after removing 12.0 cm of residue, 3.8 kg of sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.017mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 7.0 min. A It is 0.163 ml / 100g Al. N 40 P S and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0074] Example 16

[0075] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 70.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1350 / kgAl. 40 The sample size was 185 particles / kgAl; after removing 12.5cm of residue, a 4.0kg sample was taken. The area of ​​inclusions with a particle size ≥1μm was determined by the PoDFA method. S It is 0.021mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 7.5 min. A It is 0.174 ml / 100g Al. N 20 P S and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0076] Example 17

[0077] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 72.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1640 per kg Al. 40 The concentration was 265 particles / kgAl; after removing 13.0 cm of residue, 4.2 kg of sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.011mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 8.0 min. A It is 0.163 ml / 100g Al. N 20 N 40 and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0078] Example 18

[0079] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 74.0 s. 20 The number of inclusions N with a particle size ≥40μm is 1250 per kg Al. 40 The concentration was 255 particles / kg Al; after removing 13.5 cm of residue, 4.4 kg of sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.018mm 2 / kgAl; the hydrogen content (H) was obtained by Alscan method after 8.5 min. A It is 0.122 ml / 100g Al. N 20 N 40 and P S If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H AOnly when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0080] Example 19

[0081] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 76.0 s. 20 The number of inclusions N is 1500 per kg Al with a particle size ≥ 40 μm. 40 The concentration was 245 particles / kg Al; after removing 14.0 cm of residue, 4.6 kg of sample was taken and the area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.021mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 9.0 min. A It is 0.214 ml / 100g Al. N 20 N 40 P S and H A If the indicators fail to meet the standards, the melt cleanliness is deemed unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, as well as CFF filtration, until N... 20 N 40 P S H A Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0082] Example 20

[0083] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 78.0 s. 20 The number of inclusions N with a particle size ≥40μm is 900 / kgAl. 40 The sample size was 190 particles / kg Al; after removing 14.5 cm of residue, 4.8 kg of sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.014mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 9.5 min. A It is 0.140 ml / 100 g Al. N 20 N 40 P S and H A All four indicators are qualified, then proceed as follows: The calculated value of Q = 35.300 > 25 indicates that the melt cleanliness is unacceptable. The recycled aerospace aluminum melt needs to undergo repeated SNIF degassing and impurity removal, followed by CFF filtration, until N... 20 N 40 P S HA Only when all five indicators (Q, Q, and Q) are qualified can the ultra-clean recycled aerospace aluminum melt be judged as qualified.

[0084] Example 21

[0085] After SNIF degassing and impurity removal and CFF filtration, the number of inclusions with a particle size ≥20 nm in the recycled aerospace aluminum melt was determined by LiMCA after 80.0 s. 20 The number of inclusions N is 800 per kg Al with a particle size ≥ 40 μm. 40 The sample size was 130 particles / kg Al; after removing 15.0 cm of residue, 5.0 kg of sample was taken. The area of ​​inclusions with a particle size ≥1 μm was determined by PoDFA method. S It is 0.010mm 2 / kgAl; the hydrogen content H was obtained by Alscan method after 10.0 min. A It is 0.050 ml / 100 g Al. N 20 N 40 P S and H A All four indicators are qualified, then proceed as follows: The calculation yielded Q = 19.800 ≤ 25, indicating that the recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration was qualified as ultra-clean recycled aerospace aluminum melt.

Claims

1. A method for evaluating the cleanliness of recycled aerospace aluminum melt, characterized in that, The cleanliness (Q) of the recycled aerospace aluminum melt was evaluated after SNIF degassing and impurity removal and CFF filtration. Cleanliness testing included: using the LiMCA method to detect the number of inclusions with particle sizes ≥20 μm and ≥40 μm, denoted as N. 20 and N 40 The unit is: particles / kgAl, and the area P of inclusions with a particle size ≥1μm detected by the PoDFA method. S The unit is mm. 2 / kgAl; Alscan method for detecting hydrogen content H A The unit is ml / 100gAl; the specified cleanliness of recycled aerospace aluminum melt. ; The regenerated aerospace aluminum melt, after SNIF degassing and impurity removal and CFF filtration, contains N 20 >1000 particles / kgAl, or N 40 >200 per kg Al, or P S >0.015mm 2 / kgAl, or H A If the concentration is >0.150 ml / 100 g Al, repeat the SNIF degassing and impurity removal process and CFF filtration. The regenerated aerospace aluminum melt, after SNIF degassing and impurity removal and CFF filtration, contains N 20 ≤1000 particles / kg Al, N 40 ≤200 particles / kg Al, P S ≤0.015mm 2 / kgAl、H A ≤0.150ml / 100gAl, calculate the dimensionless ; The recycled aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration is considered qualified ultra-clean recycled aerospace aluminum melt if Q≤25; if Q>25, SNIF degassing and impurity removal and CFF filtration are repeated.

2. The method for evaluating the cleanliness of recycled aerospace aluminum melt according to claim 1, characterized in that, The LiMCA detection time for the regenerated aerospace aluminum melt after SNIF degassing and impurity removal and CFF filtration is 40.0-80.0 s.

3. The method for evaluating the cleanliness of recycled aerospace aluminum melt according to claim 1, characterized in that, After the recycled aerospace aluminum melt has undergone SNIF degassing and impurity removal and CFF filtration, 5.0-15.0cm of scum is removed from the surface, and then 1.0-5.0kg of samples are taken for PoDFA testing.

4. The method for evaluating the cleanliness of recycled aerospace aluminum melt according to claim 1, characterized in that, The inclusions detected by the PoDFA method were Al2O3, MgO, CaO, SiO2, MgAl2O4, ZnO, TiB2, TiC, Al4C3, and P. S This represents the total area of ​​the inclusions.

5. The method for evaluating the cleanliness of recycled aerospace aluminum melt according to claim 1, characterized in that, The regenerated aerospace aluminum melt, after SNIF degassing and impurity removal and CFF filtration, was detected by Alscan in 1.0-10.0 min.

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