Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material w...Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.展开更多
In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to c...In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to conventional methods and the national standards. The effects of variances in cell wall thickness of wood fibre and vessel, and diameter of the cell lumen as well as the tissue ratio on the quality of plywood veneer were analysed. The results show that: 1) There is a great difference in fibre cell wall thickness and diameter of the cell lumen between early wood and late wood of Eucalyptus delegatensis . 2) E. obliqua has a high wood fibre tissue ratio and the thickest fibre cell wall, but the difference in the fibre cell wall thickness between early wood and late wood is the smallest. 3) The wood fibre tissue ratio of E. regnans is smaller than that of E. obliqua, and its wood fibre cell wall is the thinnest and there is only a very small difference in fibre cell wall thickness between early wood and late wood. The difference in the diameter of wood fibre cell lumen among early wood, transition area and late wood is also small. 4) E. delegatensis has the highest tangential shrinkage rate and radial-tangential shrinkage rate, and E. obliqua has the lowest. It is the variability of wood anatomical properties of these species that cause the difference in the veneer shrinkage, and then affects plywood veneer quality.展开更多
Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electroma...Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electromagnetic shielding effectiveness were investigated. And P content, microstructure and surface feature of layers obtained at different temperatures were analyzed by energy dispersion spectrometer （EDS）, X-ray diffraction （XRI）） and scanning electron microscopy （SEM）. The results showed that layers with higher electro-conductivity and electromagnetic shielding effectiveness were obtained under the optimum conditions that plating solution was 500 mL, plating time was 30 min and plating temperature was 62℃. The results showed by EDS analysis; that P content increased gradually in a small extent with plating temperature increased. It was showed by XRD and SEM analysis that layers plated at different temperatures were all microcrystalline structure and uniform and successive, which had noticeable metal luster. Those indicated that plating temperature had little influence on microstructure and surface feature under pH value invariable.展开更多
基金The research was supported by the National Hi-Tech R ＆ D Program （863） of China （2002AA24515）. Natural Science Foundation of Heilonjiang Province （C0210） and Harbin City Youth Science Fund （2004AFQXJ027）.
文摘Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.
基金Supported by the "948" Fund Project of Chinese State Forestry (2003-4-27, 2006-4-96)
文摘In order to better understand the reasons why eucalypt veneer checks easily and severely, wood samples of three eucalypt species were selected, and their anatomical and physical properties were examined according to conventional methods and the national standards. The effects of variances in cell wall thickness of wood fibre and vessel, and diameter of the cell lumen as well as the tissue ratio on the quality of plywood veneer were analysed. The results show that: 1) There is a great difference in fibre cell wall thickness and diameter of the cell lumen between early wood and late wood of Eucalyptus delegatensis . 2) E. obliqua has a high wood fibre tissue ratio and the thickest fibre cell wall, but the difference in the fibre cell wall thickness between early wood and late wood is the smallest. 3) The wood fibre tissue ratio of E. regnans is smaller than that of E. obliqua, and its wood fibre cell wall is the thinnest and there is only a very small difference in fibre cell wall thickness between early wood and late wood. The difference in the diameter of wood fibre cell lumen among early wood, transition area and late wood is also small. 4) E. delegatensis has the highest tangential shrinkage rate and radial-tangential shrinkage rate, and E. obliqua has the lowest. It is the variability of wood anatomical properties of these species that cause the difference in the veneer shrinkage, and then affects plywood veneer quality.
基金The research was supported by the National Natural Science Foundation of China （30571454）. Natural Science Foundation of Heilongjiang Province （C0210） and Harbin City Youth Science Faud （2004AFQXJ027）.
文摘Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electromagnetic shielding effectiveness were investigated. And P content, microstructure and surface feature of layers obtained at different temperatures were analyzed by energy dispersion spectrometer （EDS）, X-ray diffraction （XRI）） and scanning electron microscopy （SEM）. The results showed that layers with higher electro-conductivity and electromagnetic shielding effectiveness were obtained under the optimum conditions that plating solution was 500 mL, plating time was 30 min and plating temperature was 62℃. The results showed by EDS analysis; that P content increased gradually in a small extent with plating temperature increased. It was showed by XRD and SEM analysis that layers plated at different temperatures were all microcrystalline structure and uniform and successive, which had noticeable metal luster. Those indicated that plating temperature had little influence on microstructure and surface feature under pH value invariable.
