In-situ observation of crystal detachment behavior in NH_4Cl-H_2O system from chilling metal surface with vibration  

作　　者：张莹 王猛 杜立成 林鑫 黄卫东 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University

出　　处：《中国有色金属学会会刊：英文版》2010年第S3期821-825,共5页Transactions of Nonferrous Metals Society of China

基　　金：Projects(50571029,50771083) supported by the National Natural Science Foundation of China;Projects(02-TZ-2008,36-TP-2009) supported by State Key Laboratory of Solidification Processing in NWPU,China

摘　　要：The crystal detachment behaviors from a chilling solid surface with vibration were investigated using a transparent NH4Cl-70%H2O alloy.The nucleation experiments of NH4Cl-70%H2O alloy were performed on a chilling surface generator with various vibration frequency from 20 to 1 000 Hz and vibration acceleration from 10 to 100 m/s2.The results indicate that the crystal detach rate increases and the grains are refined with increasing vibration acceleration under a certain vibration frequency.It is interesting to note that,when the frequency is 50 Hz,acceleration is 100 m/s2,the crystal detach rate increases sharply and the grain refinement effect is strengthened.A special grain refinement phenomenon can be observed,when the vibration acceleration and frequency are up to a critical value.A power-based definition was introduced in order to describe the relationship between the vibration parameters and imposed power on the system.It is found that a power criterion exists for the grain refinement in the current system.The crystal detachment behaviors from a chilling solid surface with vibration were investigated using a transparent NH4Cl-70%H2O alloy.The nucleation experiments of NH4Cl-70%H2O alloy were performed on a chilling surface generator with various vibration frequency from 20 to 1 000 Hz and vibration acceleration from 10 to 100 m/s2.The results indicate that the crystal detach rate increases and the grains are refined with increasing vibration acceleration under a certain vibration frequency.It is interesting to note that,when the frequency is 50 Hz,acceleration is 100 m/s2,the crystal detach rate increases sharply and the grain refinement effect is strengthened.A special grain refinement phenomenon can be observed,when the vibration acceleration and frequency are up to a critical value.A power-based definition was introduced in order to describe the relationship between the vibration parameters and imposed power on the system.It is found that a power criterion exists for the grain refinement in the current system.

关 键 词：VIBRATION CHILLING DETACHMENT REFINEMENT NH4Cl-H2O alloy 

分 类 号：TG115[金属学及工艺—物理冶金]