Interface reaction between oxide glasses and Fe-Al-Si magnetic alloy

Abstract

The interface reactions between oxide glasses and magnetic alloy, Fe-AI-Si (so-called Sendust), were analysed. The oxide glasses used were Si02-PbO, Si02-Na20, Si02-Li20 and B203-Na20 binary glasses. It was observed that the lattice constant of the alloy decreases and the saturation magnetic-flux density of the alloy increases on reaction with the glasses. It was found that the aluminium atoms in the alloy diffuse to the interface and dissolve into the glass melt as AI 3 § ions, leading to the iron-rich composition of the alloy. On the other hand, Pb 2 § Na + and H + ions in the molten glasses were reduced at the interface. Metallic lead particles about 20 I-tm in diameter were found to be dispersed in the Si02~-PbO melt. Reduced sodium was thought to evaporate from the Si02-Na20 melt, and H 2 gas bubbles were observed at the interface between B203-Na20 melt and the alloy. These reactions were analysed based on the standard free energy diagrams of oxidation-reduction reaction, and expressed as 3Pb2+g ass -'I-2AlaHoy-* 3Pb + 2AI31+ss 3Na~ass + AlaHoy~ 3Na + AI 3+ glass 6H;ass + 2Ala,,ov~ 3H2 + 2AI3+ss IntroductionMost devices are composed of many materials. As the chemical reactions at the interfaces affect the properties of the devices, it is important to determine the mechanism of the interface reactions thoroughly in order to develop composite devices with excellent properties. Oxide glasses have been extensively used for electromagnetic devices, such as integrated circuits and magnetic he~lds.There has been little attention devoted to the chemical reactions between oxide glasses and different materials. Pask and co-workers [1-9] studied the interface reaction between metals and glasses based on the concept of wettability. Takashio [10][11][12][13] studied the interface reactions between metals and glasses from the view point of thermodynamics. Tanigawa et al. [14,15] reported the reactions of Mn-Zn ferrite with lead silicate glasses and found PbO'2FezO3 is deposited during the heat treatment. Mino and Watanabe [16] studied the interface reaction between Mn-Zn ferrite and lead silicate glasses and observed that intermediate layers with many pores were formed at the interface, depending on the surface condition of the ferrite after polishing.

Effect of alloyed Al on the corrosion behaviour of Ni-base alloys in molten glass under static condition

“…Therefore, the selective dissolution of Al is the predominant oxidation reaction in 8Al alloy. Figure 11 shows the EPMA results of 10Al alloy, the surface layer of alloy has peeled off from the substrate in some region, which is ascribed to the extremely high 9 solubility of alumina in molten glass [18,[24][25][26]. According to the results by Manfreido [24], the alumina solubility is more than 20 times higher than that for chromia.…”

“…For the alloys with low Al contents (2Al and 5Al), both Al and Cr participate in the corrosion procedure as seen in Fig. 13b, where Al is oxidized as shown in Eq.3 [9]:…”

“…Extensive investigations on the corrosion of metals or alloys in molten glass have been carried out in previous literature [3,[5][6][7][8][9][10][11]. Typical pure metals such as Pt [12], Ni, Fe, Cr and Co [5] , Zr [11], together with alloys of Ni-base [7], Co-base [7] and 3 MoSi x [13][14][15] were focused on their corrosion rate, interfacial reactions, electrochemical process and so on.…”

“…In addition, the composition of glass also influences the electrode reaction at the melt/alloy interface. Since the standard potential of redox for each species differs from others [8], oxidation-reduction reaction varies with the change in glass composition [9]. For instance, the reduction redox in SiO 2 -PbO, SiO 2 -Na 2 O, and SiO 2 -B 2 O 3 glass is Pb 2+ /Pb, Na + /Na, and H + /H 2 , respectively [9].…”

Lithium in thermal energy storage: A state-of-the-art review

“…Materials are deemed important or have a high impact based on the particular properties that make them well suited for applications in which they are used. For photovoltaics, this might be the improvement of photovoltaic performance of electrochemical cells [3][4][5]; for magnetic materials it might be the magnetic flux density [6]; for thermal energy storage it might be the specific heat capacity [7][8][9][10][11] or the phase change enthalpy [12,13]. Lithium is always listed as a critical material in electric batteries [2,14].…”