Compromisul intre proprietatile magnetice si cele electrice in pulberi si compacte sinterizate composite magnetice moi

Balance between magnetic properties and electrical properties in soft magnetic composites powders and sintered compacts

ABSTRACT

​

The main goal of the project is the obtaining of new soft magnetic composites (SMC) with improved properties which could be used like magnetic cores at medium and high frequencies. Innovative idea is to replace in SMC the non-magnetic dielectric (polymer, used in classical SMC) with a magnetic dielectric (magnetic ferrite). The project is structured on three directions (objectives): (i) obtaining of nanocrystalline/nanostructured SMC powders, (ii) obtaining the nanocomposite compacts by spark plasma sintering and by cold sintering in order to preserve the phases composition and nanocrystalline state and (iii) study the balance between magnetic and electrical properties of the SMC sintered compacts. The powders will be produce by: (a) milling of mixture of alloy (ductile) and ferrite powders (brittle) to obtain the nanocomposite particles like “raisin bread” model, (b) micro-alloying between the large particles of magnetic alloy surrounded by nanosized ferrite particles (pseudo core-shell particles) and (c) obtaining by chemical method the core-shell powders (core – iron, shell - Fe3O4). The proposed research aims to optimize the microstructure influence on the magnetic coupling and electrical resistivity in nanocomposite powders and sintered compacts. The balance between magnetic and electric properties in correlation with structure/microstructure and interphase studies will be shown by a diagram of the Saturation (and/or Permeability) - Electrical resistivity.

 

 

REZUMAT

 

Proiectul este dedicat obţinerii de noi materiale compozite magnetic moi (SMC) cu proprietăţi ȋmbunătăţite, pentru miezuri magnetice utilizate la frecvenţe medii şi ȋnalte. Ideea inovativă este de a ȋnlocui dielectricul nemagnetic (polimer, folosit in materialele SMC clasice) cu un dielectric magnetic (ferită magnetică). Proiectul este structurat pe 3 direcţii: (i) obţinerea de pulberi SMC nanostructurate, (ii) obţinerea de compacte nanocompozite prin sinterizare ȋn plasmă şi sinterizare la rece, ȋn scopul prezervării stării nanocristaline şi a fazelor componente, (iii) studiul compromisului dintre proprietăţile magnetice şi cele electrice ȋn compactele sinterizate. Pulberile vor fi produse prin: (a) măcinarea unui amestec de pulberi din aliaj (ductil) cu pulberi din ferite (fragile) pentru a obţine particule de tipul « cozonac cu stafide” (“raisin bread”), (b) micro-alierea intre particule mari de aliaj magnetic ȋnconjurate cu un strat de nanoparticule de ferită (particule pseudo « core-shell ») şi (c) producerea prin metode chimice de particule « miez-coajă » (core-shell, cu miez de fier şi strat de Fe3O4). Cercetările au scopul de a optimiza infuenţa microstructurii asupra cuplajului magnetic şi a rezistivităţii electrice ȋn pulberile şi compactele nanocompozite. Compromisul dintre proprietăţile magnetice şi cele electrice ȋn corelaţie cu microstructura şi studiil la interfaţă va fi ilustrat printr-o diagramă Saturaţie (şi/sau permeabilitate) – Rezistivitate elecrică.

​

This work was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI,
project number PN-III-P4-ID-PCE-2020-2264, within PNCDI III.