Study On Carbonyl Iron And Carbonyl Iron-Epoxy Resin Composite Particles

Magnetorheological suspensions (MRS) and microwave absorber are of interest in the fields of magnetic (metal) materials.Carbonyl iron particles and iron-epoxy resin composite particles, which both MRS and microwave absorber are based on, were prepared by method of dropping Fe(CO)5 to DMF in constant temperatures and of heating the solution of Fe(CO)5/DMF stage by stage, combining in situ composite technique. The factors influencing the phase components, microstructure, electromagnetic parameters of magnetic particles and rheological performances of MRS were systematicly studied.The temperature is a key factor in the thermolysis of dropping Fe(CO)5 in constant temperature. The higher temperature, the more Fe(CO)5 decomposed in the gaseous phase. When the temperature was raised to 150, the thermolysis entirely happened in gaseous phase and the particles of 2-4um formed in long chains. With long chains broken, the plural relative permittivity (e' , e") drop and plural magnetic permeability (u' , u") rise.In heating the solution of Fe(CO)5/DMF stage by stage, the thermolysis of Fe(CO)5 goes through two courses, the transitional substance is multi-nucleus carbonyl iron and the final productions are a-Fe and iron carbide. The surfactant can prevent the producing of iron carbide and control the size of crystal grains. With the content of iron carbide in carbonyl iron decreasing, and rise, and shear stress (AT ) induced by magnetic field of MRS declines, the shear ratecorresponding to the maximum AT ('y max) heightens, and the response time of A T shortens. With the content of DMF increasing, the size of carbonyl iron reduces so that A T of MRS enhances, and increases with H more rapidly and'y max heightens.of carbonyl iron-EP composite drop with the content of ATPU, and their characterizations varying with frequency of electromagnetic wave change. With the content of SpanSO increasing, ? rises but other parameters don't almost vary. AT of MRS based on composites is lower than that of MRSbased on carbonyl iron, declines with the content of ATPU increasing butthe rising rate with H improves. With the content of SpanSO increasing, AT declines, but the rising rate falls, and y max heightens.