高长径比碱/碱土金属硼酸盐纳米晶须绿色水热合成机制及增强性能

Reinforcement via high aspect ratio nanowhiskers is an important approach for the ultra-light, super-tough and environmental benign high quality magnesium and aluminum based composites. Nevertheless, soft chemistry based methods for whiskers are generally assisted by the subsequent calcination so as to eliminate the hydroxy/crystalline water, leading to the ubiquitous technical bottleneck of corrosion,morphology preservation and pore repair. Alkali/alkaline-earth metal borates are selected as the target products of the present project, via a novel "intensified one-dimensional(ID) hydrothermal growth and trace flux assisted mild temperature calcination" technique. High aspect ratio hydrated nanosized alkali/ alkaline-earth metal borates are controllably synthesized via a non-corrosive (green),seeds，capping agents，ultrasonic and microwave induced ID hydrothermal growth under low temperature, high concentration and within short time, by the precedent separation of corrosive chlorine ions existed in the reactants..After the green hydrothermal synthesis, trace amount of flux derived from the precedent separation of chlorine ions and high temperature stable aids are employed to assist the mild temperature calcination of the hydrated metal borates, and high aspect ratio pore-free anhydrous nanosized alkali/alkaline-earth metal borates nanowhiskers are obtained,by the ID morphology preservation, pore repair and inhibition of twin crystals formation, owing to the ionic conductivity of the trace flux as well as the surface modification effect of the aids. In the application evaluation, surface coating of the as-synthesized nanosized metal borates nanowhiskers with the chemical deposition of nickel is employed so as to improve the interfacial compatability and also corresponding enhancement of the metal borates nanowhiskers reinforced magnesium based composites. In addition, in combination with the thermodynamic/dynamic analysis and also in situ characterization, the molecular simulation is performed so as to uncover the mechanism of the enhanced 1D hydrothermal growth of the hydrated nanosized alkali/alkaline-earth metal borates and also the trace flux and aids assisted pore elimination during the subsequent calcination..Besides the selected alkali/alkaline-earth metal borates,investigation of the project can also provide novel idea and pave the way for the soft chemistry based low cost and green industrial production of other 1D micro-/nanosized high crystallinity oxides.

高长径比纳米晶须增强是实现高性能镁铝基复合材料轻质高强绿色的重要手段，但晶须湿化学法制备中常需焙烧脱除羟基/结晶水，往往存在腐蚀性、形貌保持及孔洞修复难题。课题以碱/碱土金属硼酸盐为对象，采用"水热一维强化生长-微量熔剂中温焙烧"新技术，预先剥离氯离子，以晶种诱导剂超声微波等手段强化水热一维生长，低温高浓短时间内实现高长径比水合纳米碱/碱土金属硼酸盐无腐蚀绿色合成；微量熔剂与助剂辅助中温焙烧,利用熔剂离子传导及助剂表面修饰实现一维形貌保持、孔洞修复并抑制孪晶生长，制得高长径比高结晶度无水碱/碱土金属硼酸盐纳米晶须；经表面涂层改性，改善晶须与镁合金基体界面相容性；分子模拟结合过程热动力学分析及原位表征，揭示纳米碱/碱土金属硼酸盐水热一维强化生长及熔剂焙烧消孔机制。课题有望在基础及应用研究方面为轻质高强复合材料及其他高结晶度一维氧化物微纳米结构材料的湿化学法低成本绿色工业化制备提供新思路。

高长径比纳米晶须增强是实现高性能镁铝基复合材料轻质高强绿色的重要手段，但晶须湿化学法制备中常需焙烧脱除羟基/结晶水，往往存在腐蚀性、形貌保持及孔洞修复难题。课题以Mg、Ca、Sr、Ba等碱土金属硼酸盐为对象，采用“水热一维强化生长-微量熔剂中温焙烧”新技术，预先剥离氯离子，以晶型诱导剂、模版辅助等手段强化水热一维生长，低温高浓短时间内实现高长径比水合纳米碱土金属硼酸盐无腐蚀绿色合成；微量熔剂与助剂辅助中温焙烧，利用熔剂离子传导及助剂表面修饰实现一维形貌保持、孔洞修复，制得高长径比高结晶度无水碱土金属硼酸盐纳米晶须；结合过程热动力学分析及原位表征，揭示纳米碱土金属硼酸盐水热一维强化生长及熔剂焙烧消孔机制；对Mg2B2O5纳米晶须表面进行了NiO等金属氧化物涂覆修饰工艺初步探索；在高长径比碱土金属硼酸盐可控合成基础上，通过工艺优化，在离子热/水热环境中探究了其三维可控自组装，制得了具有较大比表面积、孔结构丰富的系列三维多级多孔微球（MgBO2(OH)/Mg2B2O5，Ca4B10O19·7H2O/Ca(BO2)2，Sr2B5O9Cl，Ba2(B5O9)Cl·(H2O)0.5等），深入探究了其在Pb（II）、Cr（VI）等重金属离子，以及甲基蓝、刚果红等染料吸附，负载有机催化，稀土元素掺杂发光等领域内应用前景。课题取得了系列研究成果，为碱土金属硼酸盐在基础及应用研究方面为轻质高强复合材料增强提供了有益借鉴，同时也为拓展碱土金属硼酸盐在吸附、催化、发光、储能等领域内应有进行了有益探索，为其他高结晶度一维氧化物微纳米结构材料的湿化学法低成本绿色工业化制备提供了新的思路。