Peking University

Beijing University of Technology

Jinbo Yang

Shunquan Liu

Jingzhi Han

Xiao Xi Liu

Yali Wang

Yu He

Qing Xu

Xiaoyu Ma

Ziming Wang

Jie Zhu

Suping Cui

Mingzhang Lan

Changsheng Wang

Qianjin Mao

Hongxia Guo

Zhou Liu

Wenyun Yang

The present disclosure relates to the technical field of microwave absorption, and in particular, to a multi-layer wave absorber structure and use thereof. The multi-layer wave absorber structure has a sandwich structure, and an intermediate layer of the sandwich structure is an electromagnetic loss-free dielectric layer. The electromagnetic loss-free dielectric layer includes a vacuum layer, an air layer, a paraffin layer, or a polytetrafluoroethylene layer. The added electromagnetic loss-free dielectric layer enhances impedance matching by modulating phases of electromagnetic waves, such that loss of the electromagnetic waves in a composite wave absorbing layer of the multi-layer wave absorber structure is enhanced, and an effective absorption bandwidth is further improved. The multi-layer wave absorber structure provided by the present disclosure has higher universality and operability, and has an effect of improving an effective absorption bandwidth for wave absorbing devices made of various composite wave absorbing materials.

Multi-layer wave absorber structure and use thereof

A flexible permanent magnetic material, a preparation method and an application thereof in magnetic biological effect products are provides, relating to the technical field of medical equipment. Raw materials of the flexible permanent magnetic material of the application include the following components in parts by weight: 0-70 parts of anisotropic neodymium iron boron powder and 0-40 parts of anisotropic samarium iron nitrogen powder and 3-20 parts of binder.

Flexible permanent magnetic material, preparation method and application thereof in magnetic biological effect products

A device and method for preparing a thermosetting bonded magnet are provided, the device includes a compressed air glue feeding tank and a composite-function mold. A feeding end of the compressed air glue feeding tank is connected to the composite-function mold. The composite-function mold includes a housing, the housing is disposed at an upper end and a lower end of the composite-function mold, and the housing includes a polytetrafluoroethylene upper cover and a polytetrafluoroethylene lower cover; the polytetrafluoroethylene upper cover and the polytetrafluoroethylene lower cover are respectively disposed at the upper end and the lower end of composite-function mold. The method uses a silica gel material as a binder for anisotropic magnets, and the selected raw materials and process are suitable for quickly obtaining a uniform magnet slurry. The curing process is controllable, and there is no organic solvent or heating during the mixing process.

Device and method for preparing thermosetting bonded magnet

This invention relates to a method for preparing a star-shaped polycarboxylate superplasticizer by the first esterification step with polyol and (meth)acrylic acid as main reactants and the second polymerization step. In the first step, the star-shaped polymerizable active ends were synthesized by esterification between polyol and (meth)acrylic acid in the presence of catalyst. In the second step, the final star-shaped polycarboxylate superplasticizer was prepared by radical polymerization among the product obtained in first step, unsaturated polyoxyethylene ethers, molecular weight regulator and unsaturated carboxylic acid in the presence of initiator. The production process of this invention exhibits some characteristics including simple, easily controllable, high polymerization degree, low cost and pollution free. The star-shaped molecular structure of polycarboxylate superplasticizer can be achieved through synthesizing active 'core' by esterification and 'arm' by radical polymerization. It showed better cement paste fluidity and fluidity retention, which manifested as better adaptability to cement and application performance in concrete, than both traditional linear and comb-shaped polycarboxylate superplasticizer at common or lower dosage.

Preparation method of high-performance star-shaped polycarboxylate superplasticizer

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Beijing, China

Jinbo Yang