Hu Xin,Tan Guangfan,Cai Liang,Yi Biao,Xu Dajun,Gao Zeyu,Dong Xiaoxu,Li Yusha,Zhang Yingchun
In order to meet the huge demand for millimetre-sized Li 2 TiO 3 ceramic pebbles for future fusion reactors, the aim of this work was to develop a combination of microfluidic and UV curing techniques to greatly improve the preparation efficiency. By employing a cross-junction microfluidic device, large-sized droplets were controllably generated and subsequently subjected to in-situ UV curing, enabling rapid solidification of resin-based ceramic slurries. Systematic investigations revealed critical processing parameters: (1) The rheological behavior of ceramic slurries was governed by solid content and dispersant concentration, directly influencing droplet stability during microfluidic manipulation. (2) UV curing efficacy depended on exposure time(10 ~ 40 s), aging time (30 ~ 120 s) and solid content, and the optimised conditions allow complete cross-linking of 2 mm green pebbles. (3) Post-sintering at an ultra-low heating rate (0.5 °C/min) produced Li 2 TiO 3 ceramic pebbles with a relatively dense microstructure and high crush load(42 N).This microfluidic and UV curing strategy demonstrates potential process controllability and scalability.
For solid tritium breeding materials, a high sintering temperature is essential to achieve satisfactory density, high crushing load, favorable physical and chemical properties, while lithium volatilization and grain coarsening occur at higher sintering temperature, which are not conducive to tritium production and release. Therefore, low temperature sintering of lithium containing ceramics needs to be studied. In this work, P25 titanium dioxide was hydrothermally treated in alkaline solution, and then used as titanium source to prepare Li 2 TiO 3 ceramics. The prepared Li 2 TiO 3 ceramics exhibit uniform and dense microstructure and extremely high crushing load (a.v. 78.93 ∼ 83.98 N) at a relative low sintering temperature (750 ∼ 800 °C). The thermal conductivity of Li 2 TiO 3 ceramic sintered at 800 °C is calculated to be 3.48 W/m•K at room temperature, retaining 2.50 W/m•K at 773 K, which is comparable to the values in literatures. The results suggest the sintering activity of Li 2 TiO 3 is greatly enhanced when alkaline hydrothermally treated P25 is used as titanium source.
The novel low-temperature sinterable 0.6Li 2 ZnTi 3 O 8 –0.4Li 2 TiO 3 ceramics were prepared by cofiring the mixtures of pure-phase Li 2 ZnTi 3 O 8 , Li 2 TiO 3 and ZnO–B 2 O 3 –SiO 2 glass. Li 2 ZnTi 3 O 8 and Li 2 TiO 3 phase could well coexist in the sintered samples with no second phase detected. The near-zero temperature coefficients of the resonant frequency ( τ f ) were achieved and simultaneously the desirable quality factor Q × f values could be maintained. Typically, the 0.6Li 2 ZnTi 3 O 8 –0.4Li 2 TiO 3 ceramics with 1.0 wt% ZBS addition could be well densified at only 900 °C and exhibited excellent microwave dielectric properties of ε r =25.4, Q × f =86,400 GHz and τ f =−1.0 ppm/°C, thus showing a great potential as a middle permittivity low-temperature cofired microwave dielectric material .
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