It has been rarely reported that the microwave absorption materials can exhibit excellent low-frequency EM wave absorbing properties. In this paper, we synthesized steady short carbon fibers (SCFs)@TiO 2 composites by using simple one-pot hydrothermal process. The conductive short carbon fibers could be separated by TiO 2 nanoparticles from each other and reduced the conductivity of composite materials as a whole, meeting the requirements of impedance matching . With the introduction of SCFs content, SCFs@TiO 2 composites showed improved tan δ E values at low frequencies, implying the enhanced microwave attenuation ability at low and medium frequency. We unexpectedly found that the SCFs@TiO 2 composites exhibited very strong absorbing peaks ( i.e. , −46.3 dB) at low frequencies with relatively thin matching thickness. Interestingly, when the thickness of the SCFs@TiO 2 composite was only 1.0 mm, the absorbing bandwidth with a RL value less than −10 dB was over 14.3–16.7 GHz ( i.e. , absorbing frequency bandwidth is 2.4 GHz).
Xinjiang Zhang,Feng Song,Zhiping Wei,Wenchao Yang,Zhongkui Dai
In-situ TiC/Ti titanium matrix composites were successfully fabricated through a novel approach, utilizing the reaction of graphene and Ti mixture powders in spark plasma sintering . Microstructure, hardness and compressive properties of such composites were investigated. The layered graphene nanosheets as the carbon source were dispersed in the powders, and subsequently formed uniform TiC particles in Ti matrix during the rapid sintering. The resulting TiC particles exhibited the micro- and nano-sized equiaxial structures. Such composites possessed the significantly enhanced hardness and room-temperature compressive strength comparing with the as-cast and as-sintered pure Ti. The ultimate and yield compressive strengths of as-prepared 7.0 vol% TiC incorporated composite respectively reached up to 2.64 GPa and 1.93 GPa, beyond some advanced Ti materials reported to date. In-situ micro- and nano-sized TiC particles were believed to be beneficial to harden and strengthen Ti matrix. The relevant strengthening mechanisms of such composites were discussed.
Na Zhang,Yu Liu,Jianhua Yang,Shuming Zhang,Shiyang He
The Si-TiO 2 based composites with a nanosized multi-sphere structure have been developed as novel anode for lithium ion cells . The Si spheres are highly embedded within the titanium dioxide nanoparticles via a hydrothermal synthesis route. The as-proposed sphere-stack like morphology achieves a superior cycling stability for lithium storage. The existence of TiO 2 is in favor for the mechanical stability of Si during charge-discharge and conversely reduces the obtained capacity of the composite. Furthermore, the Si/TiO 2 composite is coated by pyrolysized carbon. The reversible discharge capacity of the Si/TiO 2 /C composite reaches to 976 mAh g −1 after 50 cycles. Carbon coating is beneficial for the rate capability of the Si/TiO 2 based composite.
危险品化学品经营许可证（带存储）