Numerical investigations on cold gas dynamic spray process with nano- and microsize particles
- Authors: Jen, Tien-Chien , Li, Longjian , Cui, Wenzhi , Chen, Qinghua , Zhang, Xinming
- Date: 2005
- Subjects: Numerical simulation , Cold gas dynamic spraying , Microparticles , Copper particles , Platinum particles
- Type: Article
- Identifier: uj:5265 , http://hdl.handle.net/10210/14934
- Description: The particle velocity in cold gas dynamic spraying (CGDS) is one of the most important factors that can determine the properties of the bonding to the substrate. In this paper, the acceleration process of microscale and sub-microscale copper (Cu) and platinum (Pt) particles inside and outside De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100 nm to 50 lm, which are accelerated by carrier gas nitrogen and helium in a supersonic De-Laval-type nozzle. The carrier gas velocity and pressure distributions in the nozzle and outside the nozzle are illustrated. The centerline velocity for two types of particles, Pt and Cu, are demonstrated. It is observed that the existence of the bow shocks near the substrate prevents the smaller size particles (less than 0.5 lm) from penetrating, thus leads to poor coating in the actual practices. Furthermore, the extended straight section may have different optimal length for different size particles, and even may be unnecessary for sub-microsize particles.
- Full Text:
Numerical simulation of solute redistribution during transient liquid phase bonding processing for Al-Cu alloy"
- Authors: Jiao, Y. , Jen, Tien-Chien , Jiao, Yuning
- Date: 2011
- Subjects: Numerical simulation , Solute redistribution , Transient liquid phase , Aluminum alloys , Copper alloys
- Type: Article
- Identifier: uj:5246 , ISSN 1040-7782 , http://hdl.handle.net/10210/14852
- Description: A one-dimensional mathematical model is developed to predict the solute redistribution during the transient liquid phase (TLP) bonding process for Al-Cu alloy. The macroscopic solute diffusion in the liquid and the solid as well as for the solid transformation to the liquid because of the solute macrosegregation are considered in this study. The effects of holding temperatures and the interlayer thickness on the holding time, remelting layer thickness, and the mush zone thickness of the TLP bonding process are investigated. It is shown numerically that the holding time, the holding temperature, and the interlayer thickness influence the solute distribution strongly, which in turn influence the mush zone thickness significantly.
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