基于气泡振荡效应的碳纳米管低温水热生长机制研究

The special mechanical and thermal effects resulted from oscillation and collapse of bubbles are always achieved either by high pressure cavitation of liquid at room temperature or by high temperature heating of liquid at normal atmosphere. In this project, bubble oscillation effects will be produced by the comprehensive low temperature and low pressure conditions of hydrothermal reactions. Based on bubble oscillation effects, low temperature hydrothermal growth and deposition of carbon nanotubes (CNTs) film will be performed, in order to solve the substrate damage problems of electronic devices resulted from high temperature physical or chemical vapor growth of CNTs. The influence of hydrothermal temperature, pressure, adding amount of ethanol and other factors upon the contraction and expansion rules of bubbles will be clarified, and the oscillation mechanism of bubbles will be illuminated. The fining rules of Ni-Fe nanocatalysts by water jet and shock wave resulted from bubble oscillation and collapse will be illuminated. The collision and adsorption rules of Ni-Fe nanocatalysts and carbon atoms, as well as low temperature nucleation and growth mechanism of CNTs accelerated by bubble oscillation will be expounded, in order to establish the low temperature hydrothermal growth model of CNTs. The influence of bubble oscillation and hydrothermal convection upon the dispersion of CNTs and construction of CNTs thermal conductive network will be clarified, and the effect of CNTs dispersion, network morphology and interfacial bonding upon the heat dissipation of CNTs film will be illuminated. Hydrothermal growth of CNTs below 150℃ has not been reported. Based on the 110℃ low temperature hydrothermal growth of CNTs, this project will establish a new method for the low temperature growth of nanomaterials. Moreover, it will offer new ideas for the heat dissipation of electronic devices.

气泡振荡及溃灭产生的机械、热学等特殊效应大多通过常温液体高压空化或常压液体高温加热的手段实现。本项目拟通过低温低压的水热综合环境产生气泡振荡效应，以此实现碳纳米管薄膜低温水热生长、沉积，解决碳纳米管高温物理、化学气相生长引起的电子器件衬底破坏问题。明确水热温度、压力、乙醇加入量等对气泡收缩、膨胀的影响规律，阐明水热气泡振荡机制；阐明气泡振荡及溃灭形成水射流和冲击波细化Ni-Fe纳米催化剂作用规律；阐明气泡振荡及溃灭加快Ni-Fe纳米催化剂与碳原子碰撞、吸附，促进碳纳米管低温形核、长大作用规律，建立碳纳米管低温水热生长理论模型；明确气泡振荡和水热对流促进碳纳米管均匀分散、构筑导热网络作用规律，阐明碳纳米管分散、网络形态及界面结合对碳纳米管薄膜散热影响规律。150℃以下碳纳米管水热生长尚未见报道，本项目将在110℃碳纳米管水热生长基础上，建立纳米材料低温生长新方法，并为电子器件散热提供新思路。

气泡振荡及溃灭产生的机械、热学等特殊效应大多通过常温液体高压空化或常压液体高温加热的手段实现。本项目通过低温低压的水热综合环境产生气泡振荡效应，实现了碳纳米管原位增强金属基复合涂层的低温水热生长、沉积，解决了碳纳米管高温物理、化学气相生长引起的电子器件衬底破坏问题。研究了水热温度、压力等影响因素对水热气泡形核、长大及溃灭的影响规律；阐明了水热气泡振荡对碳纳米管低温水热生长的影响规律，揭示碳纳米管低温水热生长机理，建立了碳纳米管低温水热生长理论模型。在110℃、1.20 MPa水热反应条件下在铜基体表面制备碳纳米管增强镍基复合涂层，并测试其导热性能；结果发现，碳纳米管的生成使镍基涂层的热扩散系数和导热系数提高了将近1倍，预示着碳纳米管的低温水热制备方法在电子器件散热等方面具有良好的应用前景。籍助水热反应气泡的溃灭过程，灰口铸铁表面的片状石墨被转变为碳纳米管，在灰口铸铁表面获得了碳纳米管增强的铜铁复合涂层和镍铁复合涂层；与灰口铸铁基体相比，碳纳米管增强的铜铁复合涂层和镍铁复合涂层的磨损性能分别达到灰口铸铁基体的1.9倍和2.5倍。利用气泡溃灭现象形成水热旋涡，实现了花状镍钴纳米结构的可控生长；摩擦磨损实验结果表明，花状镍钴纳米结构在铜合金基体表面的水热沉积，显著提高了铜合金的耐磨性能。通过液相环境的取向附生过程，实现了螺旋桨状氧化钙/氧化锌微/纳结构的可控生长，这一结构表现出了优良的催化性能。受“多米诺”反应过程启发，通过激光辐照加工过程实现了球墨铸铁中石墨球向石墨烯的逐层剥离连续生长，在球墨铸铁表面形成高强韧的铁基复合涂层，其磨损性能达到了球墨铸铁基体的4.4倍。纳米材料的低温生长正引起广泛关注，本项目的碳纳米管低温水热生长研究结果，将建立纳米材料低温生长新方法，并为电子器件散热提供新思路。