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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

[en] ADAPTABLE SCANNING MAGNETIC MICROSCOPE FOR MEASUREMENT OF REMANENT FIELDS / [pt] MICROSCÓPIO MAGNÉTICO DE VARREDURA ADAPTÁVEL PARA MEDIÇÃO DE CAMPOS REMANENTES

JOAO FELIPE CHAVES E SILVA 13 June 2023 (has links)
[pt] A Microscopia Magnética de Varredura (MMV) surgiu com o objetivo de permitir a visualização de campos magnéticos de uma amostra ou material por meio de varredura, mostrando-se especialmente útil para geologia, biomedicina, caracterização de materiais e na indústria de aços. Nesse sentido, foi montada uma MMV utilizando uma estrutura de blindagem magnética de micro-metal para analisar campos remanescentes. A área sensível dos sensores foi avaliada, e foram escolhidos os sensores HQ-0811 (AKM - Asahi Kasei Microdevices), e STJ-010 (Micro Magnetics), sendo o HQ-0811 padronizado em PCBs (Printed Circuit Board) para facilitar o manuseio e aumentar a robustez do sistema. Na câmara blindada, foram utilizados dois motores de passo piezoelétricos ANC-150 (Attocube Systems), dispostos planarmente, para permitir o movimento das amostras analisadas sob o sensor montado. Para adquirir dados dos sensores, foram usados o Precision Current Source Model 6220 e o Nanovoltimeter Model 2182A (ambos Keithley), utilizando o sistema integrado da Keithley chamado Delta-Mode. Para analisar a eficácia do sistema, três amostras distintas foram analisadas para calibração, e um programa em MATLAB foi escrito para analisar as imagens e extrair a magnetização do material analisado. Além disso, uma amostra de rocha da Bacia do Parnaíba foi mapeada para demonstrar as capacidades do sistema. / [en] Magnetic Scanning Microscopy (MMV) was developed to visualize magnetic fields of a sample or material via scanning, making it particularly useful for geology, biomedicine, material characterization, and the steel industry. To this end, an MMV was assembled using a micro-metal magnetic shielding structure to analyze remanent fields. The sensors sensitive area was evaluated, and the HQ-0811 (AKM - Asahi Kasei Microdevices) and STJ-010 (Micro Magnetics) sensors were chosen, with the HQ-0811 standardized on PCBs (Printed Circuit Board) for easy handling and to enhance the system s robustness. Two piezoelectric step motors, ANC-150 (Attocube Systems), were placed in a planar arrangement in the shielded chamber to enable the analyzed samples movement under the mounted sensor. The Keithley Delta-Mode system was used in conjunction with the Precision Current Source Model 6220 and Nanovoltimeter Model 2182A (both Keithley) to acquire sensor data. Three distinct samples were analyzed for calibration, and a MATLAB program was created to extract the magnetization of the analyzed material from the images obtained. Additionally, the system s capabilities were demonstrated by mapping a rock sample from the Parnaíba Basin.

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