| Woody ceramic was a new environmental-friendly material which was developed from the 90 's of last century.The raw materials used to prepare woody ceramic were a wide range of sources,including wood,bamboo,bagasse,straw,rice husk and other renewable resources.The woody ceramic could be prepared by immersing the woody materials in thermosetting resin.The woody material was converted into soft amorphous carbon and the thermosetting resin was converted into hard glass carbon.Because of low density,high porosity,conductivity,electromagnetic shielding,etc.,the woody ceramic have great potential applications in the fields of adsorbent,catalyst carrier,waveabsorbing materials and so on.Furan resin was a synthetic resin from furaldehyde or furfuryl alcohol with a furan ring.When it was carbonized to the glass carbon,its mass loss was small and its carbon residue rate was high.In this paper,it is the first time that the furan resin was used as impregnated resin.The nano-Fe/woody ceramic composites were prepared by two ways of woody materials pretreated and furan resin pretreated,and the a-Fe nanoparticles were in situ generated in the matrix of woody ceramic.The process of woody materials pretreated was as follows.Throw moso bamboo powders(or China fir powder)into FeCl3 solution,then adjust pH by adding ammonia water.The process of furan resin pretreated was that ?-Fe2O3 nanoparticles were directly added to the furan resin,and then the nano-Fe/woody ceramic composites were made by mixing with resin and wood powder(or bamboo powder)respectively,drying,molding,and sintering.The physical and mechanical properties of nano-Fe/woody ceramic composites weretested.The formation mechanism of nano-iron/woody ceramics were investigated by fourier transform infrared spectrometer(FTIR),X-ray diffraction analyzer(XRD),thermogravimetric-differential scanning calorimetry analyzer(TG-DSC),and scanning electron microscope(SEM),and energy dispersive spectrometer(EDS).(1)The results of nano-Fe/woody ceramiccompositesprepared by the two ways show that the mass loss rate and the dimension shrinkage rate of Nano-Fe/woody ceramics increased with the increase of sintering temperature and decreased with the concentration of FeCl3,and also decreased with the addition content of ?-Fe2O3 nanoparticles.(2)The results of mechanical properties of the composites of woody materials pretreatedshow that the bending strength and the compression strength increased with the increase of sintering temperature,concentration of FeCl3 and addition content of?-Fe2O3.Under the condition of 900? and 1.00mol·L-1,the bending strength and compression strength were highest.The maximum of bending strength of nano-Fe/woodceramic composites was 11.53MPa,and the maximum of compressive strength of that was 10.95MPa;the maximum of bending strength of nano-Fe/bamboo-ceramic composites was 12.06MPa,and the maximum of compressive strength of that was 12.47MPa.The results of mechanical properties of the composites of furan resin pretreated showthat the bending strength and compressive strength increased with the increase of the sintering temperature,and increased at first,then decreased with the increase of addition content of ?-Fe2O3 nanoparticles.Under the condition of 900? and 15%,the bending strength and the compressive strengthwere highest.The maximum of bending strength and compressive strength of nano-Fe/woodceramic composites was 12.65MPa and 15.22MPa respectively.The maximum of bending strength and compressive strength of nano-Fe/bambooceramic composites was13.31MPa and 17.18MPa respectively.(3)The results of conductivity of the composites of woody materials pretreated show that the volume resistivity of the nano Fe/woodceramic composites decreased with the increase of sintering temperature and decreased with the concentration of FeCl3.The results of conductivity of the composites of furan resin pretreated show that the addition content of ?-Fe2O3 nanoparticles had a large effect on the volume resistivity of nano-Fe/woody ceramiccomposites when the sintering temperature was 650?,but have little effect at 800?.The volume resistivity was between 0.03?0.06?at 800?.The results of XRD of nano-Fe/woodceramic composites show that(002)diffraction peaks of graphite got narrow and symmetrical with the increase of the concentration of FeCl3or the addition content of ?-Fe2O3 nanoparticles,and there were also strong diffraction peaks of ?-Fe and weak diffraction peaks of Fe3C.(4)The results of the influence of the sintering temperature on the wave absorbing properties show that the wave adsorption properties of nano-Fe/woody ceramic composites prepared at 800? and 900? were better than that at 650?.The results of the wave absorbing properties of the composites of woody materials pretreated show that the wave absorbing properties were best when the concentration of FeCl3was 0.60mol·L-1 and the temperature was 800.The peak of reflect loss of nano-Fe/woodceramic composites was-16.93dB,the bandwidth of reflect loss lower than-lOdB was 2.24GHz.The peak of reflect loss of nano Fe/bamboo-ceramic composites was-13.72dB,the bandwidth of the value of reflect loss lower than-10dB was 2.56GHz when the concentration of FeCl3 was 0.60mol·L-1 and the temperature was 800?.The results of the wave absorbing properties of the composites of furan resin pretreated show that the wave absorbing properties were increased significantly when addition content of ?-Fe2O3 nanoparticles increased from 0 to7%.But when the addition content of ?-Fe2O3 nanoparticles increased to 10%or 15%,the wave absorbing properties of nano-Fe/woodceramic composites was on the decline.When the sintering temperature was 800 ? and the additioncontent of ?-Fe2O3 nanoparticles was 5%,the peak of reflect loss of nano-Fe/woodceramic composites was-15.20dB.When the sintering temperature was 800 ?and the addition content of ?-Fe2O3 nanoparticles was 5%,the peak of reflect loss of nano-Fe/bamboo-ceramic composites was-10.55dB.(5)FTIR of woody materials show that the wood powder pretreated by FeCl3 solution had two strong absorption peaks of Fe(OH)3.The results of EDS show that Fe existed on the surfaces of wood powder or bamboo powder.The results of SEM show that the ?-Fe particles were dispersed in the woodceramic,most of which were less than 100nm,The ?-Fe particles diameter increased with the increase of the concentration of FeCl3 or the addition content of ?-Fe2O3.There were mainly mesopore and micropore existed in nano-Fe/woodceramic composites.About 5nm mesopores gave the greatest contribution to volume of mesopore.There were mainly about 4nm mesopores existed in nano-Fe/bamboo-ceramic composites. |
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