Yi Zhang,Rongxia Huang,Fan Zhang,Zhihao Liang,Tianbao Xie,Hua-Tay Lin,Yejing Dai
ZrO 2 powders of various particle sizes (0.15, 0.7, 500 µm) were used to simulate loose powder bed sintering to prepare BF–BT piezoelectric ceramics. The phase structure, dielectric properties, ferroelectric properties, and piezoelectric properties were compared with the samples sintered by the conventional powder bed method (i.e., powder of the same composition as the sample). Results showed that the use of loose ZrO 2 powder bed could improve the heat conduction rate and the sintering quality of bulk BF–BT piezoelectric ceramics. The XPS results showed that the samples sintered with 500 µm ZrO 2 powder beds had the lowest concentration of Fe 2+ , exhibited the largest piezoelectric coefficients ( d 33 = 201 pC/N). In contrast, the sample sintered with a conventional powder bed under the same sintering conditions had a piezoelectric coefficient d 33 of 156 pC/N.
Kaili Liang,Yang Liu,Lishuang Hu,Jiashun Liang,Tiancheng Lv,Yanping Wang,Shuangqi Hu
Micron-sized zirconium (μZr) is a viable alternative fuel source for high-energy propellants. To explore the combustion performance of Zr-containing DAP-4-based composites, DAP-4/Zr and F/DAP-4/Zr composites were designed. The results showed that the optimized composite had high combustion performance. When DAP-4/Zr was 54:46, the sample had the highest combustion heat and the fastest flame spreading velocity. The combustion time of F/DAP-4/Zr became longer after adding F 2602 , and the flame spread was the fastest when F/DAP-4/Zr was 10:48.6:41.4. The results indicate that the introduction of μZr as a fuel in DAP-4 can improve the material's energy density and combustion characteristics.
Ultra-high pure metallic zirconium powder was successfully obtained through a two-step gradient reduction of nano-ZrO 2 in Ar atmosphere. The first reduction by Mg was to remove ~ 85% oxygen, followed by a heat-treatment step to control the particle size and specific surface area of the powder, and the final reduction by calcium was to further purify the powder and decrease oxygen to an extremely low level (0.068 wt.%). The oxygen level in the final powder meets the standard specification of Zr sponge (ASTM B349/B349M-16). Processing parameters, including the reduction temperature, the amount of Mg and MgCl 2 and the heat treatment temperature, were investigated. Thermodynamic modeling with the assistance of HSC Chemistry software was carried out to understand the reduction reaction. This study offers a novel process for producing ultra-high pure metallic zirconium powder with the potential to replace the conventional Kroll process.
The controlled construction of hybrid material structures can effectively regulate the physical, chemical, and functional properties of materials. This work explores the feasibility of coupling microdroplets technology and photopolymerization methods to achieve controllable construction of hybrid structures on the surface of ultrafine zirconium (Zr) powder, and investigates the effects of different hybrid structures on the surface mechanical properties, thermal oxidation performance, and electrostatic safety of Zr powder. The photopolymerization reaction process of PMMA on the surface of Zr powder was analyzed, revealing the principle of accelerated photopolymerization reactions within microdroplets, which was experimentally validated. Furthermore, by altering the polymerization reaction conditions and with the assistance of hydrofluoric acid (HF), a mechanism for controlling the hybrid structures on the surface of Zr powder was proposed. The results demonstrated that the collaborative effect of microdroplets and photopolymerization methods efficiently controlled the content and structural characteristics of the PMMA coating on the surface of Zr powder. The further introduction of HF was found to adjust the morphology of the surface hybrid structures and significantly improve the thermal oxidation performance and electrostatic safety of the Zr powder. These findings provided insights into the surface property regulation of active energetic materials and paved the way for the controlled preparation of inorganic–organic hybrid materials.
危险品化学品经营许可证（带存储）