Preparation And Properties Of Ferromagnetic Foam Glass-ceramics

Foamed glass is a kind of good thermal insulation material because of its low density,light weight and high temperature resistance.It has been widely used in various social industries.At the same time,magnetic material is a good microwave absorption material because of its hysteresis loss function,which has a good application prospect in electromagnetic shielding,radar stealth and other fields.The purpose of this thesis is to study a new ferromagnetic foam glass with dual functions of heat preservation and heat insulation and electromagnetic wave absorption,so that it can be used as heat preservation and heat insulation material and absorb electric waves at the same time,to achieve the purpose of electromagnetic wave shielding.Its main content is to use waste glass and slag as raw materials,add suitable foaming agent,through high temperature foaming preparation of ferromagnetic foam microcrystals.The samples were characterized and analyzed by comprehensive thermal analysis,X-ray diffraction,scanning electron microscopy,transmission electron microscopy,sample vibration magnetometer,vector network analyzer and mechanical universal testing machine.First of all,the ferromagnetic glass-ceramics powder was prepared by melt water quenching method with ferrosulfide slag as the main raw material.The preparation of ferromagnetic glass-ceramics foam was studied with SrCO₃as the foaming agent.The results show that the ferromagnetic glass foams with 97wt%ferromagnetic glass and 3wt%SrCO₃foaming agent at 1100℃for 40 minutes have A minimum volume density of0.693g/cm³,a specific saturation magnetic moment of 5.2A·m²/kg,and a compressive strength of 2.61MPa.The thermal conductivity is 0.241W/（m·K）,and the reflection loss（RL）calculated when the reflector thickness is 9mm is-12.1dB,which has strong electromagnetic wave absorption performance.Secondly,sodium calcium silicate waste glass as the main raw material,add carbon powder and ferric oxide（C+Fe₂O₃）mixture,through the reduction reaction of carbon powder and ferric oxide to produce magnetic crystal ferric oxide（Fe₃O₄）,the reaction produced by the gas to make the glass foam,so as to produce ferromagnetic foam glass.The effects of the ratio of waste glass to foaming agent,foaming temperature and foaming time on the properties of ferromagnetic foam glass-ceramics were studied.The results show that with the raw material consisting of 70wt%broken glass and 30wt%carbon powder and ferric oxide mixture（6wt%C+94wt%Fe₂O₃）,The density,thermal conductivity,specific saturation magnetic moment and compressive strength of ferromagnetic glass foamed at770℃for 15 minutes are 0.64g/cm³,0.276W/（m·K）,10.0emu/g and 2.9MPa,respectively.The minimum reflection loss is-34.0dB when the reflector thickness is 7mm and the frequency is 12.7GHz.Finally,in this thesis,a partial foaming experiment is carried out by using pre-synthesized permanent magnet strontium ferrite(SrFe₁₂O₁₉)powder and waste soda-calcium silicate glass as raw materials and strontium carbonate as foaming agent.By this process,ferromagnetic foam glass containing strontium ferrite crystals can be obtained.Based on the results of density test and magnetic properties test,the preparation technology of ferromagnetic foam glass was determined...