本文主要介绍了美国大陆公司生产的10k W PDM316D型全固态中波发射机的工作原理和特点,并以一次射频通路故障为例,提供了故障的分析方法和处理过程,此次故障点是由高频瓷环老化导致磁导率下降,致使前级输出的射频驱动信号下降,使模块不...本文主要介绍了美国大陆公司生产的10k W PDM316D型全固态中波发射机的工作原理和特点,并以一次射频通路故障为例,提供了故障的分析方法和处理过程,此次故障点是由高频瓷环老化导致磁导率下降,致使前级输出的射频驱动信号下降,使模块不能正常工作,故障具有一定的代表性,以供兄弟发射台维护人员交流学习。展开更多
A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, a...A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, and resistivity are tested at the same time. Systematic analyses of the material properties, the forming mechanism, and the regularity of woodceramics are made. The effects of the formula of raw materials, the consistencies of phenol resin, and the temperature, on the technique and the properties of woodceramics are displayed. It is shown that wheat straws can be used to produce woodceramics with this technique. The presented work provides useful ideas for the study of the preparation of woodceramics.展开更多
The family of Cr(Ⅲ) and Fe(Ⅲ)-doped rutile pigments of nominal composition (M^ⅢM^V)xTi1-2xO2, with M^Ⅲ = Cr(Ⅲ) or Fe(Ⅲ) and M'(V) = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as cera...The family of Cr(Ⅲ) and Fe(Ⅲ)-doped rutile pigments of nominal composition (M^ⅢM^V)xTi1-2xO2, with M^Ⅲ = Cr(Ⅲ) or Fe(Ⅲ) and M'(V) = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as ceramic pigments covering the yellow-ochre-brown palette. The formulations containing Fe(Ⅲ) are novel compositions not included in the commercial rutile pigments. The materials were characterized by XRD (X-ray diffraction) analysis and FTIR (Fourier transformed infrared spectroscopy). The transition temperature from anatase-to-rutile was estimated by the evolution of the spectral patterns. This crystal phase transition is responsible of the color formation. A higher distortion of TiO6 octahedra is observed in the case of (FeSb) containing cells which contribute to the enhancement of the light absorption. The coloring performance of all the formulations were evaluated by enameling the mixtures containing 5% pigments and commercial frits representative of single and double firing industrial processes. The chromatic values obtained are in the yellow to brown domain of the chromatic plot, depending on the composition of the pigment-frit batch. In the case of the Fe-glazes, and particularly the combination (FeNb), the chromatic values are close to the best yellow tinting. This new FeNb-rutile pigment could be a more benign substitute of Cr-yellow pigments. The homogeneity of the enamels was confirmed by SEM (scanning electron microscopy)-EDAX (energy dispersive X-ray analysis) microscopy.展开更多
Different ambient conditions for the synthesis of Ag(Nb0.8Ta0.2)O3 ceramics were investi- gated. The Ag(Nb0.8Ta0.2)O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disk...Different ambient conditions for the synthesis of Ag(Nb0.8Ta0.2)O3 ceramics were investi- gated. The Ag(Nb0.8Ta0.2)O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disks and sintered between 1060 ℃ and 1100 ℃ respectively. Samples were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurement. The results show that perovskite Ag(Nb0.8Ta0.2)O3 powder was easier to be synthesized in air than in vacuum at 950℃. Grain size of ceramic samples sintered in air was uniform (about 1 μm) and its dielectric loss was small for its high density. However, the samples decomposed greatly and ceramics could hardly be densified when sintered in vacuum, Thus,. higher atmospheric pressure and oxygen atmosphere would benifit the synthesis of Ag (Nb0.8Ta0.2)O3, and suppress its decomposition at high temperature.展开更多
In the field of highly integrated printed circuit board (PCB), the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate materi...In the field of highly integrated printed circuit board (PCB), the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate material with low moisture absorption and high glass transition temperature (Tg) simultaneously, a fluorenyl "Cardo" epoxy was incorporated into novolac cyanate ester resin. As an optimum curing agent for the fiuorenyl epoxy, methyl nadic anhydride (MNA) was selected. Silica powders as fillers were added into the resin composition. The partial replacement of the cyanate ester resin with the fluorenyl epoxy could reduce the moisture absorption with keeping high glass transition temperature over 300 ℃. The laminate, which was fabricated from prepregs made with 40 wt% silica-filled resin composition and glass fabric, showed high Tg of 317 ℃ and low moisture absorption of 0.57%.展开更多
文摘本文主要介绍了美国大陆公司生产的10k W PDM316D型全固态中波发射机的工作原理和特点,并以一次射频通路故障为例,提供了故障的分析方法和处理过程,此次故障点是由高频瓷环老化导致磁导率下降,致使前级输出的射频驱动信号下降,使模块不能正常工作,故障具有一定的代表性,以供兄弟发射台维护人员交流学习。
基金Supported by the item of innovating group of Hefei university of technology.
文摘A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, and resistivity are tested at the same time. Systematic analyses of the material properties, the forming mechanism, and the regularity of woodceramics are made. The effects of the formula of raw materials, the consistencies of phenol resin, and the temperature, on the technique and the properties of woodceramics are displayed. It is shown that wheat straws can be used to produce woodceramics with this technique. The presented work provides useful ideas for the study of the preparation of woodceramics.
文摘The family of Cr(Ⅲ) and Fe(Ⅲ)-doped rutile pigments of nominal composition (M^ⅢM^V)xTi1-2xO2, with M^Ⅲ = Cr(Ⅲ) or Fe(Ⅲ) and M'(V) = Sb, Nb, Ta, with x = 0.03, 0.15 and 0.25 were investigated as ceramic pigments covering the yellow-ochre-brown palette. The formulations containing Fe(Ⅲ) are novel compositions not included in the commercial rutile pigments. The materials were characterized by XRD (X-ray diffraction) analysis and FTIR (Fourier transformed infrared spectroscopy). The transition temperature from anatase-to-rutile was estimated by the evolution of the spectral patterns. This crystal phase transition is responsible of the color formation. A higher distortion of TiO6 octahedra is observed in the case of (FeSb) containing cells which contribute to the enhancement of the light absorption. The coloring performance of all the formulations were evaluated by enameling the mixtures containing 5% pigments and commercial frits representative of single and double firing industrial processes. The chromatic values obtained are in the yellow to brown domain of the chromatic plot, depending on the composition of the pigment-frit batch. In the case of the Fe-glazes, and particularly the combination (FeNb), the chromatic values are close to the best yellow tinting. This new FeNb-rutile pigment could be a more benign substitute of Cr-yellow pigments. The homogeneity of the enamels was confirmed by SEM (scanning electron microscopy)-EDAX (energy dispersive X-ray analysis) microscopy.
基金SUPPORTED BY NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA( NO. 50402011 ).
文摘Different ambient conditions for the synthesis of Ag(Nb0.8Ta0.2)O3 ceramics were investi- gated. The Ag(Nb0.8Ta0.2)O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disks and sintered between 1060 ℃ and 1100 ℃ respectively. Samples were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurement. The results show that perovskite Ag(Nb0.8Ta0.2)O3 powder was easier to be synthesized in air than in vacuum at 950℃. Grain size of ceramic samples sintered in air was uniform (about 1 μm) and its dielectric loss was small for its high density. However, the samples decomposed greatly and ceramics could hardly be densified when sintered in vacuum, Thus,. higher atmospheric pressure and oxygen atmosphere would benifit the synthesis of Ag (Nb0.8Ta0.2)O3, and suppress its decomposition at high temperature.
文摘In the field of highly integrated printed circuit board (PCB), the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate material with low moisture absorption and high glass transition temperature (Tg) simultaneously, a fluorenyl "Cardo" epoxy was incorporated into novolac cyanate ester resin. As an optimum curing agent for the fiuorenyl epoxy, methyl nadic anhydride (MNA) was selected. Silica powders as fillers were added into the resin composition. The partial replacement of the cyanate ester resin with the fluorenyl epoxy could reduce the moisture absorption with keeping high glass transition temperature over 300 ℃. The laminate, which was fabricated from prepregs made with 40 wt% silica-filled resin composition and glass fabric, showed high Tg of 317 ℃ and low moisture absorption of 0.57%.