Effect of Reynolds Number of Molten Particle on Splat Formation in Plasma Spraying

doi:10.15541/jim20140212

Abstract

Abstract:

Effect of Reynolds number on the flattening behavior of in-flight particles was investigated by slit method. Molten 6wt%-8wt% yttria-stabilized zirconia (YSZ) particles with different Reynolds numbers were collected. The morphology of splats was examined using scanning electron microscope (SEM) and 3D laser microscope. Meanwhile, the behavior of spreading, heat transfer and solidification of YSZ droplets with different Reynolds numbers were simulated by CFD software Fluent. The results show that the flattening behavior of molten particles is significantly influenced by Reynolds number when Ohnesorge number exceeds 0.2. The splat tends to splash with the increase of Reynolds number. At a lower Reynolds number, the splats exhibit a regular disc-shape. However, when Reynolds number reaches 450±20, splats begin to splash. In addition, for the original molten particles with the same diameters, the flattening ratio of molten particles in supersonic atmospheric plasma spraying (SAPS) is approximately 1.3 times as much as that in atmospheric plasma spraying (APS).

Key words: plasma spraying, molten YSZ particle, splat, Reynolds number

CLC Number:

TG174

CHEN Dan, WANG Yu, BAI Yu, WANG Yun-Hui, ZHAO Lei, Fu Qian-Qian, WANG Hai-Jun, HAN Zhi-Hai. Effect of Reynolds Number of Molten Particle on Splat Formation in Plasma Spraying[J]. Journal of Inorganic Materials, 2015, 30(1): 65-70.

Figures/Tables 12

References 23

[1]	PADTURE N P, GELL M, JORDAN E H.Thermal barrier coatings for gas-turbine engine applications.Science, 2002, 296(5566): 280-284.
[2]	PEREPEZKO J H.The hotter the engine, the better.Science, 2009, 326(5956): 1068-1069.
[3]	HAN Z H, XU B S, WANG H J, et al.A comparison of thermal shock behavior between currently plasma spray and supersonic plasma spray CeO2-Y2O3-ZrO2 graded thermal barrier coatings. Surf. Coat. Technol., 2007, 201(9/10/11): 5253-5256.
[4]	DU L Z, XU B S, DONG S J, et al.Sliding wear behavior of the supersonic plasma sprayed WC-Co coating in oil containing sand.Surf. Coat. Technol., 2008, 202(15): 3709-3714.
[5]	ZHANG X C, XU B S, TU S T, et al.Effect of spraying power on the microstructure and mechanical properties of supersonic plasma- sprayed Ni-based alloy coatings.Appl. Surf. Sci., 2008, 254(20): 6318-6326.
[6]	ZHANG X C, XU B S, WU Y X, et al.Porosity, mechanical properties, residual stresses of supersonic plasma-sprayed Ni-based alloy coatings prepared at different powder feed rates.Appl. Surf. Sci., 2008, 254(13): 3879-3889.
[7]	BAI Y, HAN Z H, LI H Q, et al.Structure-property differences between supersonic and conventional atmospheric plasma sprayed zirconia thermal barrier coatings.Surf. Coat. Technol., 2011, 205(13/14): 3833-3839.
[8]	BAI Y, HAN Z H, LI H Q, et al.High performance nanostructured ZrO2 based thermal barrier coatings deposited by high efficiency supersonic plasma spraying.Appl. Surf. Sci., 2011, 257(16): 7210-7216.
[9]	YOKOI K.Numberical studies of droplet splashing on a dry surface: triggering a splash with the dynamic contact angle.Soft Matter, 2011, 7(11): 5120-5123.
[10]	PASANDIDEH-FARD M, PERSHIN V SCHANDRA. Splat shapes in a thermal spray coating process: simulations and experiments.J. Therm. Spray Technol., 2002, 11(2): 206-217.
[11]	BOBZIN K, BAGCIVAN N, PARKOT D.Simulation of PYSZ particle impact and solidification in atmospheric plasma spraying coating process.Surf. Coat. Technol., 2010, 204(8): 1211-1215.
[12]	XIONG H B.Melting and oxidation behavior of in-flight particles in plasma spray process.Int. J. Heat Mass Transfer, 2005, 48(25/26): 5121-5133.
[13]	LI L.Particle characterization and splat formation of plasma sprayed zirconia. J. Therm. Spray Technol., 2006, 15(1): 97-105.
[14]	BERTAGNOLL M.Modeling of particles impacting on a rigid substrate under plasma spraying conditions.J. Therm. Spray Technol., 1995, 4(1): 41-49.
[15]	KANG C W.Numerical and experimental investigations of splat geometric characteristics during oblique impact of plasma spraying.Appl. Surf. Sci., 2011, 257(24): 10363-10372.
[16]	BRANDON J R.Phase stability of zirconia-based thermal barrier coatings. Part I. Zirconia-yttria alloys.Surf. Coat. Technol., 1991, 46(1): 75-90.
[17]	ANDRE M.Thermal contact resistance between plasma-sprayed particles and flat surfaces.Int. J. Heat Mass Transfer, 2007, 50(9/10): 1737-1749.
[18]	PASANDIDEH-FARD M.On the Spreading and solidification of molten particles in a plasma spray process: effect of thermal contact resistance.Plasma Chem. Plasma Process., 1996, 16(1): 83s-98s.
[19]	FUKUMOTO M, HUANG Y.Flattening mechanism in thermal sprayed nickel particle impinging on flat substrate surface.J. Therm. Spray Technol., 1999, 8(3): 427-432.
[20]	ZHAO W T, WU J H, BAI Y, et al.Melting refining mechanisms in supersonic atmospheric plasma spraying.Plasma Chem. Plasma Process., 2012, 32(6): 1227-1242.
[21]	MADEJESKI J.Solidification of droplets on a cold surface. Int. J. Heat Mass Transfer., 1976, 19: 1009-1013.
[22]	YOSHIDA T, OKADA T, HAMATAMI H, et al.Integrated fabrication process for solid oxide fuel cells using novel plasma spraying.Plasma. Sources Sci. Technol., 1992, 1: 195-201.
[23]	LIU H, LAVERNIA E, RANGEL R.Numerical simulation of impingement of molten Ti, Ni, and W droplets on a flat substrate.J. Therm. Spray Technol., 1993, 2(4): 369-378.

Spray methods	Ar /slpm	H₂ /slpm	Power P/kW	Voltage U/V	Current I/A	Spray distance D/mm	Feed rate /(g?min^-1)	Temperature T/℃	Velocity v/(m?s^-1)
SAPS	70.5	22	68.6	138	497	110	35	2919.0±2.0	505.0±3.8
SAPS	75.0	21	58.5	124	472	90	35	2813.9±2.5	484.5±9.3
SAPS	60.3	15	44.5	125	356	90	35	2685.4±2.7	464.5±3.0
SAPS	75.0	21	58.5	124	472	80	35	2680.0±14.7	544.5±13.5
SAPS	75.0	21	58.5	124	472	100	35	3066.4±10.1	544.2±13.0
SAPS	75.0	21	58.5	124	472	120	35	3196.4±10.1	584.4±28.0
APS	32.9	8.225	44.0	67.6	650	90	38.4	2804.4±5.4	224.0±5.1
APS	42.3	10.575	44.0	71.4	611	90	38.4	2740.2±3.7	231.0±4.2
APS	51.7	12.925	44.0	75.6	585	90	38.4	2683.6±4.5	233.3±3.6
APS	47.0	11.750	48.0	74.0	650	80	38.4	2680.0±3.3	238.5±3.1
APS	47.0	11.750	48.0	74.0	650	100	38.4	2934.1±4.2	244.0±3.1
APS	47.0	11.750	48.0	74.0	650	120	38.4	2804.7±5.1	226.5±2.3

Spray methods	Ar /slpm	H₂ /slpm	Power P/kW	Voltage U/V	Current I/A	Spray distance D/mm	Feed rate /(g?min^-1)	Temperature T/℃	Velocity v/(m?s^-1)
SAPS	70.5	22	68.6	138	497	110	35	2919.0±2.0	505.0±3.8
SAPS	75.0	21	58.5	124	472	90	35	2813.9±2.5	484.5±9.3
SAPS	60.3	15	44.5	125	356	90	35	2685.4±2.7	464.5±3.0
SAPS	75.0	21	58.5	124	472	80	35	2680.0±14.7	544.5±13.5
SAPS	75.0	21	58.5	124	472	100	35	3066.4±10.1	544.2±13.0
SAPS	75.0	21	58.5	124	472	120	35	3196.4±10.1	584.4±28.0
APS	32.9	8.225	44.0	67.6	650	90	38.4	2804.4±5.4	224.0±5.1
APS	42.3	10.575	44.0	71.4	611	90	38.4	2740.2±3.7	231.0±4.2
APS	51.7	12.925	44.0	75.6	585	90	38.4	2683.6±4.5	233.3±3.6
APS	47.0	11.750	48.0	74.0	650	80	38.4	2680.0±3.3	238.5±3.1
APS	47.0	11.750	48.0	74.0	650	100	38.4	2934.1±4.2	244.0±3.1
APS	47.0	11.750	48.0	74.0	650	120	38.4	2804.7±5.1	226.5±2.3

Property of YSZ	Value	Property of YSZ	Value
Density	5890 kg/m³	Solidus temperature	2923.13 K
Specific heat	713 J/( kg?K)	Liquidus temperuture	3023.13 K
Thermal conductivity	2.32 W/(m?K)	Thermal contact resistance	10^-6 m²?K/W
Viscosity	0.008 kg/( m?s)	Surface tension	0.43 N/m
Molecular weight	123	Property of substrate	Value
Standard state enthalpy	-11.006×10⁸ J/mol	Density	8400 kg/m³
Reference temperature	298.15 K	Specific heat	575 J/( kg?K)
Melting heat	7.07×10⁵ J/kg	Thermal conductivity	18.779 W/( m?K)

Property of YSZ	Value	Property of YSZ	Value
Density	5890 kg/m³	Solidus temperature	2923.13 K
Specific heat	713 J/( kg?K)	Liquidus temperuture	3023.13 K
Thermal conductivity	2.32 W/(m?K)	Thermal contact resistance	10^-6 m²?K/W
Viscosity	0.008 kg/( m?s)	Surface tension	0.43 N/m
Molecular weight	123	Property of substrate	Value
Standard state enthalpy	-11.006×10⁸ J/mol	Density	8400 kg/m³
Reference temperature	298.15 K	Specific heat	575 J/( kg?K)
Melting heat	7.07×10⁵ J/kg	Thermal conductivity	18.779 W/( m?K)

Sample	Spray methods	Temperature /℃	Velocity /(m·s^-1)	Original diameter /μm	Re	We	Oh	Splashing or not
1	SAPS	2680.0	544.5	6.0	414.7	2.44×10⁴	0.376	No
2	SAPS	2680.0	544.5	7.5	518.4	3.05×10⁴	0.337	Yes
3	SAPS	3066.4	544.2	6.8	563.5	2.76×10⁴	0.294	Yes
4	SAPS	3066.4	544.2	5.0	414.1	2.03×10⁴	0.342	No
5	SAPS	3196.4	584.4	5.0	469.0	2.34×10⁴	0.326	No
6	SAPS	3196.4	584.4	6.4	600.3	2.99×10⁴	0.288	Yes
7	APS	2680.0	238.5	14.5	439.0	1.13×10⁴	0.241	Yes
8	APS	2934.1	244.0	16.5	578.4	1.35×10⁴	0.200	Yes
9	APS	2934.1	244.0	15.6	546.8	1.27×10⁴	0.206	No
10	APS	2804.7	226.5	17.9	549.0	1.26×10⁴	0.204	Yes