Study on Preparation and Performance of La0.6Sr0.4MnO3/Fe-Ni Composite Absorbing Material

FeNi3 alloy was prepared by vacuum ball milling method, La0.6Sr0.4MnO3 was prepared by sol-gel method, FeNi3 alloy and La0.6Sr0.4MnO3 were mixed in different proportions and then combined by vacuum ball milling. The measurement of the absorbing performance of the sample found that the addition of FeNi3 alloy is beneficial to increase the absorbing capacity of La0.6Sr0.4MnO3, and the degree of improvement is closely related to the mixing ratio. When the mixing ratio is 1:3, the effect is the best. The absorption performance of the frequency band is improved more significantly, and the absorption in the low frequency range of the 1:3 ratio sample is nearly 4 times higher than that of La0.6Sr0.4MnO3.

The absorbing material is a kind of material that can dissipate the incident electromagnetic wave energy through its own absorption and conversion effect, thereby reducing the electromagnetic wave reflection. Microwave absorbing material is an important military stealth functional material, and its development has attracted widespread attention at home and abroad. Due to the shortcomings of traditional single-component absorbing materials such as low absorbing efficiency and narrow absorbing frequency bands, their applications are restricted. Therefore, the research and development of composite absorbing materials has become an important direction for the development of current absorbing materials.

The perovskite structure La1-xSrxMnO3 material is a well-known giant magnetoresistive material, and it also has good electromagnetic wave absorption characteristics, but the material has the disadvantages of poor absorption efficiency in low frequency bands and low overall absorption efficiency. Fe-Ni alloy, a new type of magnetic absorbent, has good absorbing properties in low frequency bands, and has a higher overall permeability, but at the same time its impedance matching ability, oxidation resistance, and acid and alkali corrosion resistance are far inferior La1-xSrxMnO3 with perovskite structure. Therefore, this article combines the above considerations to prepare the perovskite structure material La0.6Sr0.4MnO3 and FeNi alloy. The two kinds of absorbing materials are combined in different proportions by vacuum ball milling, and appropriate annealing treatment is carried out, which greatly improves La0.6Sr0. 4MnO3 Absorbing performance.

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Using analytical pure La(NO3)2·6H2O (analytical purity), 50% Mn(NO3)2 solution, Sr(NO3)·6H2O (analytical purity), concentrated ammonia water and citric acid as raw materials, according to the molecular formula La0.6Sr0 .4MnO3 Weigh the proportioned raw materials and dissolve them in deionized water to form a mixed solution (the molar ratio of metal ions to citric acid is 1:1), stir the solution with a JB-4A electromagnetic stirrer, and then use concentrated Ammonia adjusts the pH value of the solution to make it neutral. Concentrate the solution at low temperature to obtain a sol, and then dry it in an LB-1 vacuum drying oven. Take out the dried sample and grind it into powder. Repeat this twice and put it into a resistance furnace It is fired at 300 ℃ to remove the organic matter in the sample, and then sintered at 800 ℃ for 8 hours to obtain the sample, which is marked as the L sample.

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Weigh the iron and nickel powder raw materials according to the molecular formula FeNi3, mix them evenly, put them into the ball mill tank, and vacuum the ball mill tank. The ball-to-material ratio is 10:1, the speed is 200 rad/min, and the ball milling time is 85 h. The mixed raw materials are powder alloyed on the -1SP planetary mill. Then add anhydrous Yichun to the ball mill and perform wet milling for 1 hour. Finally, the ball milled sample is naturally dried, and the prepared sample is labeled F.

Put the prepared FeNi3 and La0.6Sr0.4MnO3 powders according to different mass ratios of 1:x, (x=1, 2, 3, 4), and put them into the ball mill tank, the ball to material ratio is 10:1, and the ball mill tank is pumped After vacuum, ball milling and compounding were performed at a speed of 200 rad/min, and a compound sample was prepared after the ball milling time for 3 hours, labeled as F1-Lx (x=1, 2, 3, 4), and then the physical properties of each sample were tested.

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The phase composition of the sample was analyzed with the TW1830 X-ray diffractometer produced by the Philip Company in the Netherlands, and the scanning range was 20°~80° (the target material was Cu, the working voltage was 40 volts, and the working current was 40 mA). The AV3618 microwave vector network analyzer was used to measure the absorbing characteristics, complex permeability, and complex permittivity of each sample.

(1) FeNi3 alloy was prepared by powder metallurgy, and La0.6Sr0.4MnO3 with perovskite structure was prepared by sol-gel method. Then use vacuum ball milling to add FeNi3 alloy to La0.6Sr0.4MnO3 in different proportions to effectively improve the wave absorbing performance of La0.6Sr0.4MnO3.

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(2) The electromagnetic parameter test of the sample found that the imaginary part of the complex permittivity of the sample is reduced after the FeNi3 alloy is compounded, and the imaginary part of the complex permeability is increased. The microwave absorption of each sample is mainly caused by the magnetic loss.

(3) By testing the absorbing performance of the sample, it is found that after FeNi3 is added to La0.6Sr0.4MnO3, its microwave absorption is significantly increased, especially in the low frequency range, where F1-L3 is at low The frequency range is nearly 4 times higher than that of La0.6Sr0.4MnO3. This shows that the F1-L3 sample is a good absorbing material.

Founded in 2015,Zunhua Baorui Titanium Equipment Co.,Ltd. is a manufacturer specializing in pvd vacuum ion coating equipment. The company’s products mainly include large plate coating machine, large tube collating machine, tool coating machine and LOW-E glass production line. Mr.Wang baijiang ,general manager of the company ,has been engaged in vacuum coating industry for more than 30 years. He continuously improve production technology, improve product performance and devote himself to provide customers with better product experience and higher production efficiency.