Study On Prepartion And Properties Of Iron/Soda Lime Silicate Glass Soft Magnetic Composites

Soft magnetic composite is a sort of newly-born soft magnetic materials. The focus of this study lies in decreasing the inner stress of iron powder in order to releasing its corresponding magnetic property. The dissertation takes use of sol-gel method and powder metallurgy method to prepare iron/soda lime silicate glass soft magnetic composites with the purpose of manufacturing a new material capable of eliminating stress and annealing under high temperature. Hence, testing approaches like microscope, scanning electron microscopy, transmission electron microscopy, soft magnetic testing system, electronic tensile tester as well as dilatometer to make analysis of the micro-structure and properties of composite materials. In this paper, I will analyze the impact mechanism of iron particle size, volume fraction, annealing temperature towards the thermal expansion behavior of Fe/silicate glass soft composite materials, electricity, magnetism and mechanics pe rformance. And with these achievements, it is undoubted that there will be bright prospect in the areas of soft magnetic composites and hard magnetic composites.Through theoretical calculation and thermal expansion coefficient test, the composite of new soft magnetic composite are determined as Si O2 54wt%, Na2 O 41wt%, Ca O 5wt%. Comparing different coupling agent on the effect of iron powder coated Si O2 membrane, the silane coupling agent KH550 is determined as the coupling agent of iron powder coated Si O2 membrane. After comparing multiple devising approaches, the preparation method takes use of bilayers(Si O2 layer and silicate glass xerogel) wrapping iron powder and produce composite materials by means of cold compressing companied by annealing process finally.Reactant Fe O and Fe3O4 are observed at interface of iron powder and silicate glass, and the distribution is discontinuous. When annealing temperature is greater than 700℃, microcrystalline Na12Ca3Fe2(Si6O18)2 precipitates. The thermal residual stress determines the residual stress in iron/soda lime silicate glass soft magnetic composite. The thermal residual stress in iron powder is compressive when annealing temperature is smaller than 700℃, tensile when annealing temperature is greater than 700℃, equal to zero when annealing temperature is 700℃. The static soft magnetism of iron/soda lime glass soft magnetic composite is studied with iron powder average particle size, volume fraction and annealing temperature. The influence factors of static magnetism include thermal residual stress, demagnetization field, interface area, doping in iron powder and magnetic domain. The thermal residual stress is the main factor of static magnetism. The best annealing temperature of iron/soda lime glass soft magnetic composite is 700℃. The greater the average particle size and volume fraction of iron powder, the static magnetism is greater.The influence factors of core loss of iron/soda lime glass soft magnetic composite include thermal residual stress, demagnetization field, interfa ce area, doping in iron powder, magnetic domain, average particle size of iron powder, dc resistivity of the composite and the count of magnetic object. The thermal residual stress is the main factor of changing of hysteresis loss and core loss with anneal ing temperature. Hysteresis loss is the main in core loss. Furthermore, residual loss compared with the literature is small about an order of magnitude.It reveals the facture mechanism of iron/soda lime silicate glass soft magnetic composite. The fracture process of composites can be divided into three phases: elastic deformation, strain hardening and damage softening. After reaching fracture strength, fracture commences to expand, which takes place in two-phase interface or glass phase. There are two ways of fracture expanding, one is continuous expansion through crossing the loading direction of iron powder border side directly; the other is fracture stops expanding when meeting iron powder, and new fracture will emerge in the surroundings of iron powder as loading continues, and then continues to expand by connecting with the original main crack. After acquiring the average particle size, volume fraction and variation discipline of annealing temperatures of iron/soda lime silicate glass soft magnetic composite materials, it is found that the influential factors of its bending property are the density of composite and thermal residual stress. As to fracture toughness, its influential elements are density, micro-crystal, interface area and thermal residual stress in glass.