The preparation and micwave-absorbing behavior of nanosize PSZFe magnetic particles were studied.Nanosize PSZFe magnetic particles were prepared as following:nanosize Fe particles generated by themal decomposition of ...The preparation and micwave-absorbing behavior of nanosize PSZFe magnetic particles were studied.Nanosize PSZFe magnetic particles were prepared as following:nanosize Fe particles generated by themal decomposition of Fe(CO)-5 in organic solvents were encapsulated with synthesized polysilazane(PSZ) precursor and then irradiated under ultraviolet light.PSZFe particles were characterized by using transmission election microscope(TEM),X-Ray powder diffraction(XRD) and vibrating sample magntometer(VSM),and their microwave-adsorbing properties were measured by means of a vector network analyzer.The influence of the polysilazation layer on corrosion and magnetization of PSZFe particles and the relationship between polysilazation layer and micwave-absorbing behavior of PSZFe particles were investigated.Results showed that the average diameter of PSZFe particles was 30 nm,the structure of iron in PSZFe magnetic particles was α-Fe.The formation of a PSZ layer on nanosize Fe particles enchanced the corrosion resistance of PSZFe.In addition,PSZFe particles coated with 3 wt% PSZ demonstrated high corrosion resistance and fine microwave-absorbing ability as well.The reflection loss was less than -10 dB in the range of 9^8～16 GHz,and a reflection loss value of -20 dB was detected at 13 GHz.展开更多
In order to enhance the reactivity of the silyl-containing ceramic precursor,a hyperbranched silyl-containing polymer with low viscosity and plenty of terminal vinyl-groups was prepared.A novel AB4 type monomer,bis（N...In order to enhance the reactivity of the silyl-containing ceramic precursor,a hyperbranched silyl-containing polymer with low viscosity and plenty of terminal vinyl-groups was prepared.A novel AB4 type monomer,bis（N,N-diallylamino）methylsilane,was synthesized first by aminolysis of MeHSiCl2 and then was polymerized via hydrosilylation reaction using H2PtCl6 as the catalyst.The polymerization process was monitored by FT-IR spectroscopy.The polymer product was purified via precipitation using ethyl ether and acetonitrile and was analysed by using（）1H-NMR、（）29Si-NMR and FT-IR spectroscopy.The results indicated that the polymer was hyperbranched polycarbosilazane,and α-hydrosilylation was the main reaction.The degree of branching（DB） of the hyperbranched polymer was 0.56 calculated from the（）29Si-NMR spectrum,and the average molecular weight（Mw）was 13 580 g/mol determined by light scattering method.It was found that there still existed a lot of functional vinyl end groups,which can be used as promising reaction centers for curing or modification of the polycarbosilazane.展开更多
文摘The preparation and micwave-absorbing behavior of nanosize PSZFe magnetic particles were studied.Nanosize PSZFe magnetic particles were prepared as following:nanosize Fe particles generated by themal decomposition of Fe(CO)-5 in organic solvents were encapsulated with synthesized polysilazane(PSZ) precursor and then irradiated under ultraviolet light.PSZFe particles were characterized by using transmission election microscope(TEM),X-Ray powder diffraction(XRD) and vibrating sample magntometer(VSM),and their microwave-adsorbing properties were measured by means of a vector network analyzer.The influence of the polysilazation layer on corrosion and magnetization of PSZFe particles and the relationship between polysilazation layer and micwave-absorbing behavior of PSZFe particles were investigated.Results showed that the average diameter of PSZFe particles was 30 nm,the structure of iron in PSZFe magnetic particles was α-Fe.The formation of a PSZ layer on nanosize Fe particles enchanced the corrosion resistance of PSZFe.In addition,PSZFe particles coated with 3 wt% PSZ demonstrated high corrosion resistance and fine microwave-absorbing ability as well.The reflection loss was less than -10 dB in the range of 9^8～16 GHz,and a reflection loss value of -20 dB was detected at 13 GHz.
文摘In order to enhance the reactivity of the silyl-containing ceramic precursor,a hyperbranched silyl-containing polymer with low viscosity and plenty of terminal vinyl-groups was prepared.A novel AB4 type monomer,bis（N,N-diallylamino）methylsilane,was synthesized first by aminolysis of MeHSiCl2 and then was polymerized via hydrosilylation reaction using H2PtCl6 as the catalyst.The polymerization process was monitored by FT-IR spectroscopy.The polymer product was purified via precipitation using ethyl ether and acetonitrile and was analysed by using（）1H-NMR、（）29Si-NMR and FT-IR spectroscopy.The results indicated that the polymer was hyperbranched polycarbosilazane,and α-hydrosilylation was the main reaction.The degree of branching（DB） of the hyperbranched polymer was 0.56 calculated from the（）29Si-NMR spectrum,and the average molecular weight（Mw）was 13 580 g/mol determined by light scattering method.It was found that there still existed a lot of functional vinyl end groups,which can be used as promising reaction centers for curing or modification of the polycarbosilazane.
