纳米颗粒电场辅助冷喷涂数值研究
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摘要
在喷管出口和基板之间外加电场来加速带电颗粒,并对带电纳米铜颗粒进行电场辅助冷喷涂气固两相流数值研究,分析在气流和电场力的综合作用下颗粒粒径、电荷量、基板电压等参数对颗粒速度的影响。结果表明,电场辅助冷喷涂不适合微米级颗粒,但非常适合纳米颗粒喷涂,且粒径越小,颗粒撞击速度越大,电场力加速效果越显著;颗粒电荷量、基板电压越大,颗粒撞击速度越高。
Numerical study was carried out to investigate the gas-solid flow in the process of electrostatic-force-assisted cold spraying( ECS)copper nano-particles. Electrostatic field was introduced between the nozzle exit and the substrate in order to achieve higher impact velocities of the charged particles. The influences of particle diameter,electric charge and substrate voltage on the velocities of copper particle accelerated by the gas flow and the electric field force were analyzed. The results show that ECS is not suitable for spraying the microparticles. However,it is very suitable for spraying nano-particles. When smaller particles are applied,higher impact velocities can be obtained and the accelerating effect induced by the electrical force is more remarkable. Larger electric charge and substrate voltage will lead to higher impact velocities of the charged particles.
Numerical study was carried out to investigate the gas-solid flow in the process of electrostatic-force-assisted cold spraying( ECS)copper nano-particles. Electrostatic field was introduced between the nozzle exit and the substrate in order to achieve higher impact velocities of the charged particles. The influences of particle diameter,electric charge and substrate voltage on the velocities of copper particle accelerated by the gas flow and the electric field force were analyzed. The results show that ECS is not suitable for spraying the microparticles. However,it is very suitable for spraying nano-particles. When smaller particles are applied,higher impact velocities can be obtained and the accelerating effect induced by the electrical force is more remarkable. Larger electric charge and substrate voltage will lead to higher impact velocities of the charged particles.
引文
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[2]王洪涛,陈枭,纪岗昌,等.WC/Fe Al金属间化合物基金属陶瓷涂层的冷喷涂制备[J].金属热处理,2013,38(3):70-73.Wang Hongtao,Chen Xiao,Ji Gangchang,et al.Preparation of WC/Fe Al intermetallic compound based cermet coating by cold spraying[J].Heat Treatment of Metals,2013,38(3):70-73.
[3]Pattison J,Celotto S,Khan A.Standoff distance and bow shock phenomena in the cold spray process[J].Surface&Coating Technology,2008,202(8):1443-1454.
[4]Chun Doo-Man,Choi Jung-Oh,Lee C,et al.Effect of stand-off distance for cold gas spraying of fine ceramic particles(<5μm)under low vacuum and room temperature using nano-particle deposition system(NPDS)[J].Surface&Coatings Technology,2012,206(8/9):2125-2132.
[5]Wang Y Y,Liu Y,Li C J,et al.Electrical and mechanical properties of nano-structured Ti N coatings deposited by vacuum cold spray[J].Vacuum,2012,86(7):953-959.
[6]Sahner K,Kaspar M,Moos R.Assessment of the novel aerosol deposition method for room temperature preparation of metal oxide gas sensor films[J].Sensors and Actuators B:Chemical,2009,139(2):394-399.
[7]郑建新,金耀辉,刘传绍.真空冷喷涂铜颗粒加速特性数值研究[J].表面技术,2013,42(1):5-8.Zheng Jianxin,Jin Yaohui,Liu Chuanshao.Numerical study on accelerating characteristics of copper particles in vacuum cold spraying process[J].Surface Technology,2013,42(1):5-8.
[8]Jen T C,Pan L P,Li L J,et al.The acceleration of charged nanoparticles in gas stream of supersonic De-Lavel-type nozzle coupled with static electric field[J].Applied Thermal Engineering,2007,27(17/18):2877-2885.
[9]Takana H,Ogawa K,Shoji T,et al.Computational simulation of cold spray process assisted by electrostatic force[J].Powder Technology,2008,185(2):116-123.
[10]Takana H,Ogawa K,Nishiyama H,et al.Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist[J].Journal of Fluids Engineering,2008,130(8):081701-1-7.
[11]唐文勇,陈清华,柴伟伟,等.激波对电场辅助冷喷涂纳米颗粒速度的影响[J].材料热处理学报,2012,33(11):153-157.Tang Wenyong,Chen Qinghua,Chai Weiwei,et al.Effects of shock wave on velocity of nano-particles in electrostatic-force assisted cold spraying[J].Transactions of Materials and Heat Treatment,2012,33(11):153-157.
[12]郑建新,郝婉君.电场辅助冷喷涂超微颗粒加速特性研究[J].热加工工艺,2014,43(16):141-144.Zheng Jianxin,Hao Wanjun.Study on accelerating characteristics of ultrafine particles in the process of electrostatic-force-assisted cold gas dynamic spray[J].Hot Working Technology,2014,43(16):141-144.