Papers by Author: Zhao Yang Zeng

Abstract: Because of the dark green color similar to vegetation, tetranitro iron phthalocyanine has great potentiality in military camouflage application. Tetranitro iron phthalocyanine was synthesized in the method of improved microwave-assisted synthesis. By single-variable controlling principle, the optimal synthesis conditions in laboratory for tetranitro iron phthalocyanine composing was determined. The spectra difference under different conditions between tetranitro iron phthalocyanine and green vegetation was analyzed. The possibility for using tetranitro iron phthalocyanine as green paint in camouflage was discussed

Abstract: For the purpose of investigating the influence of graphite addition on the property of carbonyl iron absorber, some samples were made by mixing graphite and carbonyl iron powders. The electro-magnetic parameters were then measured and compared between samples containing different graphite mass ratio. Microstructures of these samples were observed to make sure that additions were uniformly distributed in these samples. By this way, the influence of graphite addition was systematically analyzed.

Abstract: For the purse of improving the microwave absorption ability of carbonyl iron, Co power was chosen as additions to add into the sample. Both analyze and measurement proved that the addition of Co power effectively decreased the conductivity, while not obviously destroyed the magnetic property of the sample. In this way, the addition of Co power improved the sample surface matching effect, and correspondingly, the absorption ability is increased.

Abstract: For the purpose of investigating the influence of different process condition on alkali reduce rate and mass increase rate, the techniques of polyester fiber pretreatment, electroless copper plating, and electroless silver plating were carefully analyzed and compared. It was found that the best coursing condition was: 5.5 mol/L concentration, 65°C temperature, 30 minutes reaction time, 1:200 bath ratio. Under these conditions, the alkali reduction rate was 11.38%. As for copper plating liquid concentration of 0.08 mol/L, pH value 9.5, 80°C temperature, liquid silver plated concentration 0.02 mol/L, the coating weight gain rate was 52.1%. Microcosmic morphology on coating surface and surface resistance test show that the fabric was evenly coated with Cu, Ag, metal ions, which resulting in excellent electric conductivity and good electromagnetic shielding performance.

Abstract: As many influence factors and technical problems should be taken into account in the scheme selection decision of multi-band camouflage screen design, a method based on hierarchical grey relational analysis combing analytic hierarchy process (AHP) and grey relational analysis (GRA) was developed. The hierarchy model was constructed firstly, and the judging matrixes were established through analytic hierarchy process. The weight value for each index which effects the evaluation was determined accordingly. The relational degree between an individual alternative scheme and the ideal alternative and the worst alternative are calculated by grey correlation degree, and the evaluation degree is calculated according the grey correlation degree and weight value. Based on the relational degree a quality order for the alternative schemes can be obtained. Experiment was carried out, which proved that the method mentioned in this paper had both strict mathematical theory basis and good practical utility. This method can be also used in scheme selection decision of other camouflage designs.

Abstract: Microwave diffraction behavior of microwave absorbing ceramics was investigated by numerical calculation, and effective electro-magnetic parameters of the ceramics was obtained by comparing the diffraction behavior with that of homogeneous material. Then, the calculated results were compared with the results of effective medium models, aiming to investigate the applicability of these models. The obvious difference between these results were pointed out, also discussed is the possible reason for this difference.

Abstract: In order to compare the absorbing properties of different microwave-absorbing agents and their mixture, this paper has selected two typical microwave-absorbing agents which respectively are carbon fiber resistance microwave-absorbing agents and ferrite magnetism microwave-absorbing agents, and took them as monolayer absorbing materials. Then used MG formula to calculate the effective electromagnetic parameter of their mixture under different proportion at X band, and finally analyzed their absorbing properties separately. Then through contrasting the impedance matching characteristic and attenuation coefficient of the materials, it is proved that adding carbon fiber in ferrite can not improve absorption properties. Although the ability of attenuating electromagnetic wave would be enhanced when resistance materials and magnetism materials are blend with each other, doping will destroy the materials’ impedance matching characteristic because most resistance materials have high permittivity. It makes reflection strengthen and can not improve absorbing properties.

Abstract: In order to improve absorbing properties of material effectively, enhance the ability of attenuating electromagnetic wave, and at the same time, make the impedance matching with air to the most extent, this paper mixed ferrite magnetism microwave-absorbing agents with semiconductor particulates. We got the effective EM parameter of the mixture using effective EM parameter model, and then analyzed absorption properties. As the result, it figured out the cubage proportion and conductance of semiconductor particulates based on the resistance matching principle. Through calculating the reflection ratio、impedance matching characteristic and attenuation coefficient of the material, it is proved that mixing ferrite magnetism microwave-absorbing agents with semiconductor particulate which has less permittivity could reduce real complex permittivity and increase imaginary complex permittivity of the composite material. It was able to enhance the ability of attenuating electromagnetic wave, improve absorbing properties, and meanwhile do not destroy the impedance matching characteristic with air.

Abstract: Two methods are widely used to represent the microwave absorption properties of ceramics: measuring the values of electromagnetic parameters such as permeability and permittivity, or directly measuring the reflection rate of a metal-backed slab sample made of this material. However, do these two methods coincide with each other If not, which method should be used as right way to represent this kind of ceramics To answer these questions, both methods are carried out on the same ceramics, of which the results are compared. Distinct difference between these measured results is found, and the possible reasons for the difference are also discussed.

Abstract: As a kind of information protecting technology, material compositing becomes more and more important. The microwave properties of composite materials depend on many aspects, but stuffing is the most critical. The effect of conductive stuffing, magnetic stuffing, and the mixed stuffing are compared and analyzed in this report. It is found that conductive stuffing has the lowest absorbing behavior, while magnetic stuffing is best choice for composite. The mixing of conductive stuffing and magnetic stuffing does not result in better absorbers.