Effects of Shock Waves on the Particle Acceleration for Cold Gas Dynamic Spray

2004 ◽  
Author(s):  
Tien-Chien Jen ◽  
Longjian Li ◽  
Wenzhi Cui ◽  
Qinghua Chen ◽  
Xinming Zhang
Keyword(s):  
Particle Diameter ◽  
Cold Gas Dynamic Spraying ◽  
Acceleration Process ◽  
Two Phase ◽  
Carrier Gas ◽  
Micro Scale ◽  
Gas Dynamic ◽  
Bow Shocks ◽  
Cold Gas Dynamic Spray ◽  
Cold Gas

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 micro-scale and sub micro-scale 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 100nm to 50μm, which are accelerated by carrier gas Nitrogen in a supersonic De-Laval-type nozzle. The carrier gas velocity and pressure distributions in the nozzle and outside the nozzle are illustrated. The center-line 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 μm) from penetrating, thus leads to poor coating in the actual practices.

The Acceleration of Micro- and Nano-Particles in Supersonic De-Laval-Type Nozzle

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Longjian Li ◽  
Qinghua Chen ◽  
Wenzhi Cui ◽  
Xinming Zhang
Keyword(s):  
Particle Density ◽  
Particle Diameter ◽  
Nano Particles ◽  
Cold Gas Dynamic Spraying ◽  
Acceleration Process ◽  
Two Phase ◽  
Micro Scale ◽  
Compression Waves ◽  
Gas Dynamic ◽  
Weak Shocks

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. The acceleration of gas to particles is strongly dependent on the densities of particles and the particle size. In this paper, the acceleration process of micro-scale and nano-scale copper (Cu) and platinum (Pt) particles in De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100nm to 50μm, which are accelerated by carrier gas Nitrogen in a supersonic De-Laval-type nozzle. The results show that cone-shape weak shocks (compression waves) occur at the exit of divergent section and the particle density has significant effect on the accele ration of micro-scale particles. At same inlet condition, the velocity of the smaller particles is larger than the larger particles at the exit of the divergent section of the nozzle.

The Effects of the Distance Between Nozzle and Substrate on Cold Gas Dynamic Spray Process

2005 ◽  
Author(s):  
Longjian Li ◽  
Wenzhi Cui ◽  
Qinghua Chen ◽  
Tien-Chien Jen ◽  
Quan Liao
Keyword(s):  
Supersonic Nozzle ◽  
Strong Shock ◽  
Two Phase ◽  
Carrier Gas ◽  
Compression Waves ◽  
Spray Process ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

In this paper, numerical simulations were performed for the gas-particle two phase flow in the cold gas dynamic spray process to investigate the acceleration of micro- and nanoparticles with diameters ranging from 100nm to 50μm. Nitrogen (N2) and Helium (He) were chosen as the carrier gas, respectively. The acceleration of carrier gas to particles in the De-Laval-Type supersonic nozzle was strongly dependent on the characteristics of flow field, as well as the densities and the size of the particles. Two kind of particles Copper (Cu) and Platinum (Pt) were chosen as the spraying materials. The computed results showed that the flow structures of the carrier gas were very different for different gas and different spraying distance, which resulted in consequently different accelerating features. The cone-shape weak shocks (compression waves) occurred at the exit of divergent section, and the bow-shaped strong shock wave was found right before the substrate, which played a resistance role to the particles and prevented the smaller particles from approaching on the substrate.

The Effects of the Distance Between Nozzle and Substrate on Cold Gas Dynamic Spray Process

2009 ◽  
Author(s):  
Longjian Li ◽  
Qinghua Chen ◽  
Wenzhi Cui ◽  
Tien-Chien Jen ◽  
Yi-Hsin Yen ◽  
...  
Keyword(s):  
Supersonic Nozzle ◽  
Strong Shock ◽  
Two Phase ◽  
Carrier Gas ◽  
Compression Waves ◽  
Spray Process ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

In this paper, numerical simulations were performed for the gas-particle two phase flow in the Cold Gas Dynamic Spray (CGDS) process to investigate the acceleration of micro- and nanoparticles with diameters ranging from 100nm to 50μm. Nitrogen (N2) and Helium (He) were chosen as the carrier gas, respectively. The acceleration of carrier gas to particles in the De-Laval-Type supersonic nozzle was strongly dependent on the characteristics of flow field, as well as the densities and the size of the particles. Copper particles (Cu) were chosen as the spraying materials. The computed results showed that the flow structures of the carrier gas were very different for different gas and different spraying distance, which resulted in consequently different accelerating features. The cone-shape weak shocks (compression waves) occurred at the exit of divergent section, and the bow-shaped strong shock wave was found right before the substrate, which played a resistance role to the particles and prevented the smaller particles from approaching on the substrate.

Optimization of Cold Gas Dynamic Spray Processes by Computational Simulation

2007 ◽  
Author(s):  
Hidemasa Takana ◽  
Kazuhiro Ogawa ◽  
Tetsuo Shoji ◽  
Hideya Nishiyama
Keyword(s):  
Shock Wave ◽  
Electrostatic Force ◽  
Particle Diameter ◽  
Integrated Model ◽  
Viscous Drag ◽  
Spray Process ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

An integrated model of compressible thermofluid, splat formation and coating formation for a cold dynamic spray process has been established. In-flight behavior of nano-micro particles and the interaction between the shock wave and the particles in a supersonic jet flow impinging onto the substrate and further particle acceleration with electrostatic force are clarified in detail by considering viscous drag force, flow acceleration, added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis and electrostatic force. The effect of electrostatic acceleration becomes more significant with the decrease in particle diameter even in the presence of unavoidable shock wave. As a result, electrostatic acceleration can broaden the application range of operating particle diameter in a cold gas dynamic spray process to form a robust and activated coating. Finally, based on the integrated model, the coating thickness characteristics in an electrostatic assisted cold dynamic spray process are evaluated.

The Effects of Optimized Nozzle-Substrate Distance on Cold Gas Dynamic Spray (CGDS) Process

2010 ◽  
Author(s):  
Yi-Hsin Yen ◽  
Sung-Cheng Wong ◽  
Tien-Chien Jen ◽  
Qinghua Chen ◽  
Quan Liao
Keyword(s):  
Particle Size ◽  
Gas Flow ◽  
Aluminum Substrate ◽  
Coating Quality ◽  
Carrier Gas ◽  
Substrate Distance ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas

This paper presents research that is focused on the particle coating quality of Cold Gas Dynamic Spray (CGDS) process. The coating quality is affected by several different factors, namely the carrier gas species, nozzle-substrate distance, nozzle inlet pressure and the coating particle size. The intent of this research is to use numerical simulations to predict the coating quality and to find the optimized nozzle-substrate distance and particle size in CGDS process by tuning the factor of nozzle-substrate distance and the coating particle size. Air was chosen as the carrier gas to accelerate copper (Cu) particles, which have diameters ranging from 2–50μm.. There are two main target factors, the nozzle-substrate distance and particle size, which are going to affect the coating quality in this study. In the first part, 14 sets of nozzle-substrate distance models ranging from 2.5mm to 100 mm were setup to study the air velocity, density, temperature and pressure contour through the De-Laval nozzle to the aluminum substrate. In the second part, 49 sets of different particle sizes ranging from 2–50μm in diameter were computed. The particle’s impact velocities on the aluminum substrate were applied to 12 different nozzle-substrate distance models. The bow shock wave, a high pressure gradient region, formed in front of the aluminum substrate, makes the copper particles decelerate in front of the substrate. The results showed that the gas flow velocity contours was affected by different nozzle-substrate distances, which caused different particle accelerating characteristics.

Effect of a conical separation region on cold gas-dynamic spraying

2012 ◽  
Vol 53 (6) ◽  
pp. 948-953 ◽  
Author(s):  
A. P. Alkhimov ◽  
V. F. Kosarev ◽  
S. V. Klinkov ◽  
A. A. Sova
Keyword(s):  
Cold Gas Dynamic Spraying ◽  
Separation Region ◽  
Gas Dynamic ◽  
Cold Gas

Thin Film Coatings of WO3 by Cold Gas Dynamic Spray: A Technical Note

2005 ◽  
Vol 14 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Ha Yong Lee ◽  
Young Ho Yu ◽  
Young Cheol Lee ◽  
Young Pyo Hong ◽  
Kyung Hyun Ko
Keyword(s):  
Thin Film ◽  
Technical Note ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Gas Dynamic ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Cold Gas
Sign in / Sign up

Export Citation Format

Share Document