Preparation And Wave Absorption Performance Of Lightweight Composite Absorbing Agents Based On Hollow Glass Microspheres

With the development of radar detection technology and the complexity of the battlefield environment,stealth technology has become a hot spot for research in various countries.As an important part of stealth technology,the research and development of radar absorbing materials is of great significance.Meanwhile,the use of materials with lightweight characteristics can further reduce the density of absorbers and solve the problems of rapid maneuverability,multiple loading,and lack of long endurance of equipment.As the new type of inorganic functional material,hollow glass microsphers are of great interest because they are hollow,lightweight,heat resistant and have good chemical stability.To prepare a new microwave absorbing agent with the properties of light weight and high efficiency wave absorption,the hollow glass microspheres as the core were modified in this thesis by nickel and conductive polymers individually and alternatively,respectively.Firstly,the hollow glass microsphers,as the substrate,achieved to plat the nickel via the method of metal chemical plating.The thickness of the nickel plating layer on the surface of the hollow glass microsphers was controlled by regulating the concentration of the plating solution.The quantitative relationship between the thickness of the nickel plating layer and dielectric constant and magnetic permeability were investgated,respecitvely.The results showed that the loss ability of the nickel/hollow glass microsphere composite microwave absorbing agent increased as the thickness of the nickel plating layer increased when the concentration of nickel sulfate hexahydrate in the plating solution was less than or equal to0.175 g/m L.When the concentration of the plating solution was greater than or equal to 0.25g/m L,the nickel plating layer was too thick,resulting the peeling of the nickel layer from the surface of the hollow glass microsphers,weakening of the electromagnetic loss capacity,reducing the wave absorption performance.Secondly,the polypyrrole/hollow glass microsphere composite was prepared by in situ polymerization.The amounts of polypyrrole coating were controlled by adjusting the amount of pyrrole monomer.The influences of the polypyrrole coverage on the electromagnetic parameters and the microwave absorbing performance were investigated,respectively.The results showed that the loss of electromagnetic waves increased with the increase of polypyrrole coating.The minimum reflection loss(-22.91 d B)was reached at the frequency of 18.00 GHz with the polypyrrole of 37.70 wt%and the thickness of 1.5 mm.At last,the ternary composite polypyrrole/nickel/hollow glass microsphere microwave adsorbing agent was prepared by in-situ polymerisation of polypyrrole on the surface of nickel/hollow glass microsphere composite.Firstly,the influence law of polypyrrole coating amount on electromagnetic parameters and wave absorption performance of ternary composite absorbent was studied,and the optimal polypyrrole coating amount was obtained;secondly,the optimal polypyrrole coating amount was selected,the addition amount of absorbent in paraffin wax was changed,and the optimal addition amount of polypyrrole/nickel/hollow glass beads ternary composite absorbent was obtained.When the polypyrrole coating on the surface of the nickel/hollow glass microsphere composite was 29.38 wt%and the addition in paraffin wax was 20 wt%,the minimum reflection loss of the ternary composite polypyrrole/nickel/hollow glass microsphere was-32.01 d B and the effective absorption bandwidth was 2.24 GHz(4.88-7.12 GHz)with the thickness of 5.0 mm and the frequency of 5.84 GHz.Significantly,the density was only 0.57 g/cm~3.This ternary composite polypyrrole/nickel/hollow glass microsphere has the potential as an new lightweight microwave adsorbing agent in practical application.