Expanded Perlite Adsorbed Ni-Zn/Mn-Zn Ferrite And Its Application In Wave Absorbing Cement Mortar

With the rapid development of information technology and electronic technology,different frequency bands of electromagnetic waves fill the people's living space.While playing the role of communication,electromagnetic waves also bring many negative effects,such as electromagnetic interference,information leakage and harms to human health.The development of new cement-based materials with excellent wave absorption and application in buildings is of great significance in solving the above problems.In view of the poor impedance matching and low absorption performance of cement-based microwave absorbing materials,this paper relies on the National Natural Science Foundation of China?51372183?.The application of Ni-Zn/Mn-Zn ferrite-absorbing expanded perlite and its application in absorbing wave cement mortar was studied.The specific research content and major achievements are as follows:The use of expanded perlite loaded with Ni-Zn/Mn-Zn ferrite instead of fine aggregate is proposed,the technical idea of preparing composite wave-absorbing cement mortar by nano-Fe₃O₄ ferrofluid and nano-TiO₂ absorber incorporated into cement paste is adopted,the expanded perlite porous structure can exert multiple scattering and scattering effects on electromagnetic waves,and the absorbing agent can exert a magnetic loss/dielectric loss effect on the electromagnetic waves.An expanded perlite loaded with Ni-Zn/Mn-Zn ferrite was prepared?Absorbing component?,the Ni_0.5Zn_0.5Fe₂O₄/Mn_0.36Zn_0.68Fe_1.96O₄ ferrite precursor was loaded on the expanded perlite by sol-gel method,and then the perlite loaded precursor was heated at 5°C/min.The temperature was raised to 800°C for calcination,and after being kept for 2 hours,expanded perlite having a surface uniformly loaded with Ni_0.5Zn_0.5Fe₂O₄/Mn_0.36Zn_0.68Fe_1.96O₄ ferrite particles was obtained.Using the absorbing functional components of expanded perlite loaded with Ni-Zn/Mn-Zn ferrite,a cement mortar with excellent microwave absorbing properties and certain physical and mechanical properties was prepared.The effect of the addition of the functional components of the expanded perlite,the matching layer,and the thickness of the sample on the wave absorption properties of the cement mortar was systematically studied.In 8¹8GHz frequency range,the double-layer cement-based plate sample is mixed 15%expanded perlite which loaded with Ni-Zn ferrite,when its thickness is 30mm,it has the best wave absorption performance,its reflection loss is less than-10dB in the whole frequency band,and the bandwidth less than-15dB is 7.4GHz,its 28d flexural and compressive strength are respectively6.5MPa and 29.6MPa.Nano Fe₃O₄ magnetic fluid and nano-TiO₂ were prepared.It was mixed into the cement mortar containing Ni-Zn/Mn-Zn ferrite perlite functional components separately,and the change of absorbing properties of the prepared cement-based specimens was studied.The results show that,in the range of the dosage used,both have a slight adverse effect on the absorption properties of the cement mortar samples,which are due to excessive magnetic loss media?Fe₃O₄ magnetic fluid,Ni-Zn/Mn-Zn ferrite?leads to a poorer impedance matching of the material to the electromagnetic wave,and a decrease in the microwave absorbing properties caused by uneven dispersion of the nano-TiO₂ powder.