Silica aerogel/epoxy composite, a kind of efficient thermal insulation material, was
prepared by doping silica aerogel of different sizes into epoxy resin through thermocuring process.
The results of thermal experiments showed that silica aerogel/epoxy composite had a lower thermal
conductivity (0.105W/(m·k) at 60 wt% silica aerogel) and higher serviceability temperature
(Martens heat distortion temperature: 160°C at 20 wt% silica aerogel). In addition, the composite
doping larger size (0.2-2mm) of silica aerogel particle had lower thermal conductivity and higher
Martens heat distortion temperature. Based on the results of SEM and FT-IR, the thermal transfer
model was established. Thermal transfer mechanism and the reasons of higher Martens heat
distortion temperature have been discussed respectively.
Lithium niobate thin films have been deposited on Pt/Ti/SiO2/Si substrates by the Pechini
method from metal carboxylate gels and heat-treated at temperatures ranging from 400 to 600°C. The
thermal decomposition of the metal carboxylate precursor gels has been studied by differential thermal
analysis and thermogravimetry. The products derived from calcination of the gels at different
temperatures have been characterized by Fourier transform infrared, Roman spectrum and X-ray
diffraction. Scanning electron microscopy analysis shows the surface of the films to be smooth, dense and
crack-free. Electric properties measurement indicates that the LiNbO3 films demonstrate a ferroelectric
hysteresis loop. The remanent polarization (Pr) and coercive field (Ec) are 17.89 μC/cm2 and 35.23 kV/cm,
respectively.
Silica xerogels were prepared by sol-gel process and non-supercritical drying. Two kinds of
reinforcements, SiC whisker and short carbon fiber (CF), were chosen to control the shrinkage during
drying process and improve the mechanical properties of xerogels. Microstructure and mechanical
properties of samples were examined. It was found that the addition of SiC whisker could greatly improve
the elastic modulus of silica xerogels, while short CF could prominently decrease the volume shrinkage
ratio but could not improve the elastic modulus. Analysis showed that the difference between the two
reinforcement mechanisms was caused by the interface and the size of the doped fiber and whisker.
In this work, PZT (Zr/Ti=52/48) thin films have been prepared using aqueous organic gel
method. The desired metal cations are chelated in a solution using citric acid and
ethylenediaminetertraacetic acid (EDTA) as the chelating agents. The thermal decompostion of the
metal carboxylate precursors gels have been studied by TG/DTA and the products derived from
calcinations of the gels at different temperatures have been characterized by XRD and SEM. By
heat-treatment at 650°C for 2h, PZT thin films with smooth and crack-free surface could be
achieved. The thickness of each layer was 50nm. Electric properties measurement indicated that the
PZT films demonstrated a ferroelectric hysteresis loop. The remanent polarization(Pr) and coercive
field (Ec) were 20.7μC/cm2 and 75.5kV/cm, respectively. The dielectric constant and the dielectric
loss at 100 kHz of the films were 930 and 0.045, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.