摘要
火焰合成法是一种凝聚相纳米材料制备手段。该文聚焦于火焰合成凝聚相纳米材料形貌、组分和微观结构调控技术,关注火焰稳定性、火焰温度与组分场、产物粒径与形貌和产物理化性质4个方面。火焰稳定性调控主要总结了旋流稳定法(包括旋流数的计算方法和设计准则)、辅助火焰法、保护壳气法和高焓前驱液法等;火焰温度与组分场调控主要包括燃空当量比调节、冷却网架设、淬冷环架设和前驱液调控等技术;产物粒径与形貌可通过基底材料、液滴微爆、超细雾化、高沸点活性剂添加和等离子体放电等技术进行调控;产物理化性质可由晶体结构、元素掺杂、核壳类结构设计和后热处理等方法调控。前两方面注重材料外部火焰结构调控,后两方面注重材料内部性质调控,在实际实验或生产中,需要根据具体情况综合运用。
[Significance]Flame synthesis is a method for the preparation of condensed-phase nanomaterials.It is energy efficient,cost effective and has the potential for large scale industrial applications.[Progress]This review examined the control technologies for the morphology,composition and microstructure of flame synthesized condensed-phase nanomaterials from four aspects,i.e.,flame stability,flame temperature and species profiles,product particle size and morphology,and product physicochemical properties.The flame stability control part mainly introduced the swirl stabilization method,including both strong swirl stabilization(Sg,tan>5 or S>0.6)and weak swirl stabilization(S≤0.6).The calculation and design criteria of different swirl numbers for different types of swirlers were evaluated.Methods such as the addition of pilot flame,the increase of active component concentrations at the flame nozzle,the use of high-enthalpy precursor solution,and the addition of sheath gas were also summarized.For the control of flame temperature and species profiles,adjustments might be made to the fuel-air equivalence ratio,oxygen flow rate for atomization,or precursor liquid flow rate and concentration.The installation of the cooling meshes and quenching rings,water addition to precursor liquid and high-enthalpy solvent replacement were also good strategies.The particle size and morphology of the product might be controlled indirectly by adjusting the flame temperature and species profiles which could affect the particle dynamics process.From another perspective,it might also be regulated by substrate materials,droplet microexplosion,precursor ultrafine atomization,inclusion of high boiling point active agent,and plasma discharge,etc.These were realized by controlling the droplet size before particle formation and regulating particle attributes for precipitation,collision,and condensation,thereby changing its size and shape.Four primary approaches for controlling physicochemical properties were summarized,including crystal structur
作者
沈畅
邵森
郭祺峰
周宇昕
游小清
SHEN Chang;SHAO Sen;GUO Qifeng;ZHOU Yuxin;YOU Xiaoqing(Center for Combustion Energy,Tsinghua University,Beijing 100084,China;Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education,Tsinghua University,Beijing 100084,China)
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2023年第4期546-559,共14页
Journal of Tsinghua University(Science and Technology)
基金
国家重点研发计划项目(2021YFA0716204)。
关键词
火焰合成
燃烧学
纳米材料
flame synthesis
combustion
nanomaterials
