Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods
Abstract
:1. Introduction
2. Materials and Methods
2.1. Physical Model and Simulation Domain
2.2. Numerical Simulation Method
2.3. Verification of Simulation Results
2.4. Interaction between Particles in Cold Spray by LS-DYNA
3. Results
3.1. Characteristics of Thickness Coating around the Holes
3.2. Particle Velocity in the Holes
3.3. Particle Interaction during Impacting onto the Substrate
4. Discussion
5. Conclusions
- A hypothesis for the original formation reason of holes can be proposed: particles are too close when they impact onto the substrate. The repellant force between the particles perpendicular to the impaction direction will lead to porosity if the particles are too close. A much lower flattening ratio occurred for succeeding particles if they were too close to the same point, because the momentum energy contributes to the former particle’s deformation. There is a high probability of the above two phenomena, resulting from high powder-feeding rate, forming the original hole.
- The holes cannot be filled up for deceleration of the compressed layer and collision between particles and inner face of hole. In relatively wider holes, coating can be deposited in the bottom, while in relatively narrower holes, coating cannot be deposited. The deposition efficiency is much lower inside the hole than on the plane substrate, which will lead to hole growth.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Geometric Parameters and Working Conditions | Value |
---|---|
D1 (pre-chamber diameter) | 20 mm |
D2 (throat diameter) | 2 mm |
D3 (nozzle exit diameter) | 6 mm |
L1 (pre-chamber length) | 10 mm |
L2 (converging length) | 15 mm |
L3 (diverging length) | 180 mm |
L4 (standoff distance from nozzle exit to substrate) | 20 mm |
L5 (depth of hole) | 0, 2, 5, 10 mm |
H1 (diameter of hole) | 0.5, 1, 3 mm |
Pressure in pre-chamber | 3.0 MPa |
Temperature in pre-chamber | 673 K |
Powder feeding rate | 1 g/s |
Re | a1 | a2 | a3 |
---|---|---|---|
Re < 0.1 | 0 | 24.0 | 0 |
0.1 < Re < 1.0 | 3.69 | 22.73 | 0.0903 |
1.0 < Re < 10.0 | 1.222 | 29.1667 | −3.8889 |
10.0 < Re < 100.0 | 0.6167 | 46.5 | −116.67 |
100.0 < Re < 1000.0 | 0.3644 | 98.33 | −2778 |
1000.0 < Re < 5000.0 | 0.357 | 148.62 | −4.75 × 105 |
5000.0 < Re < 10000.0 | 0.46 | −490.456 | 5.787 × 105 |
10000.0 < Re < 50000.0 | 0.5191 | −1662.5 | 5.4167 × 105 |
Material | Copper |
---|---|
Modulus of elasticity, E (N/m2) | 0.124 × 1012 |
Poison’s ratio, n | 0.34 |
Density, ρ (kg/m3) | 7900 |
Yield stress, A (MPa) | 90 |
B (MPa) | 292 |
n | 0.31 |
C | 0.025 |
Reference strain rate, 0 (1/s) | 1.00 |
m | 1.09 |
Tmelt(K) | 1356 |
T0 (K) | 293 |
Specifc heat, Cp (J/kg·K) | 383 |
Inelastic heat fraction, p | 0.90 |
D1 | 0.00 |
D2 | 0.00 |
D3 | 0.00 |
D4 | 0.00 |
D5 | 0.00 |
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Huang, G.; Wang, H.; Li, X.; Xing, L. Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods. Coatings 2017, 7, 2. https://doi.org/10.3390/coatings7010002
Huang G, Wang H, Li X, Xing L. Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods. Coatings. 2017; 7(1):2. https://doi.org/10.3390/coatings7010002
Chicago/Turabian StyleHuang, Guosheng, Hongren Wang, Xiangbo Li, and Lukuo Xing. 2017. "Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods" Coatings 7, no. 1: 2. https://doi.org/10.3390/coatings7010002
APA StyleHuang, G., Wang, H., Li, X., & Xing, L. (2017). Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods. Coatings, 7(1), 2. https://doi.org/10.3390/coatings7010002