Design and optimization of rectangular cold spray nozzle: Radial injection angle, expansion ratio and traverse speed

In this work an influence of cold spray nozzle displacement parameters on the properties of copper-silicon carbide cold spray deposits is considered. In particular the influence of nozzle traverse speed and distance between deposited tracks on the coating porosity and behavior during compressive tests was analyzed. It was shown that cold spraying at low nozzle traverse speed leads to formation of thick tracks with quasi-triangular cross-section. As a consequence, the particle impact angle on the sides of spraying track increases that. Thus, the particle deformation at impact on the track periphery becomes insufficient and local porosity value rises. Increase of nozzle traverse speed allows increasing coating density and mechanical properties due to amelioration of particle deformation conditions. Compressive tests revealed significant anisotropy of mechanical properties of copper-silicon carbide cold spray deposits. In particular, compressive strength measured in vertical direction (perpendicular to the substrate) was significantly higher than one measured in horizontal plane (parallel to substrate). This anisotropy could be explained by the orientation of particle deformation pattern during impact.

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Effect of the expansion ratio and length ratio on a gas-particle flow in a converging-diverging cold spray nozzle

Metals and Materials International ◽

10.1007/s12540-009-0967-x ◽

2009 ◽

Vol 15 (6) ◽

pp. 967-970 ◽

Cited By ~ 10

Author(s):

Hyun-Boo Jung ◽

Jong-In Park ◽

Sung-Han Park ◽

Hyung-Jun Kim ◽

Chang-hee Lee ◽

...

Keyword(s):

Cold Spray ◽

Expansion Ratio ◽

Particle Flow ◽

Length Ratio ◽

Spray Nozzle

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Laser Assisted Cold Spray for Improved Adhesion of Soft Materials to Hard Substrates—Case Study for Copper Coatings on Steel

10.31399/asm.cp.itsc2021p0596 ◽

2021 ◽

Author(s):

Jean-Gabriel Legoux ◽

Bruno Guerreiro ◽

Dominique Poirier ◽

Jason D. Giallonardo

Keyword(s):

Cold Spray ◽

Large Diameter ◽

Soft Materials ◽

Traverse Speed ◽

Spot Size ◽

Nitrogen Gas ◽

High Adhesion ◽

Copper Coatings ◽

Helium Gas ◽

Hard Substrates

Abstract In cold spray, high adhesion of soft materials on hard substrates is commonly achieved by using helium as the propelling gas. This is the case of copper coatings on steel where adhesion may reach values as high as 60 to 80 MPa (glue failure), however, helium is a limited, expensive natural resource, and the use of more abundant nitrogen gas is preferred in an industrial setting. Unfortunately, when using nitrogen gas, little to no adhesion is obtained. In order to eliminate the use of helium gas we studied how laser assisted cold spray could lead to an improvement in adhesion of nitrogen sprayed copper coatings. In this work, several laser parameters (e.g., power and spot size) and process parameters (traverse speed, relative position laser spot vs. gas jet) were varied at a coupon level. Upon optimization, an equivalent adhesion to the coatings prepared with helium was obtained. Furthermore, the cross section of the coatings showed that the copper particles penetrated the steel, similar to what is observed when using helium gas. Optimization of these parameters for application to large diameter (~559 mm) cylinders was also performed. A discussion on the mechanisms which contribute to achieving high adhesion considering the use of helium versus laser assistance is provided.

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Parametric Redesign of a Convergent-Divergent Cold Spray Nozzle

Thermal Spray 2021: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2021p0221 ◽

2021 ◽

Author(s):

Florentina-Luiza Zavalan ◽

Aldo Rona

Keyword(s):

Cold Spray ◽

Gas Flow ◽

High Hardness ◽

Cold Spraying ◽

Spray Nozzle ◽

Industry Standard ◽

Particle Velocities ◽

Radial Spread ◽

Cold Metal ◽

Carrier Gas Flow

Abstract The generation of a high velocity carrier gas flow for cold metal particle applications is addressed; with specific focus on titanium cold spraying. The high hardness of this material makes cold spraying titanium difficult to achieve by industry standard nozzles. The redesign of a commercial conical convergent-divergent cold spray nozzle is achieved by the application of aerospace design codes; based on the Method of Characteristics; towards producing a more isentropic expansion by contouring the nozzle walls. Steady threedimensional RANS SST k-ω simulations of nitrogen are coupled two-way to particle parcel tracking in the Lagrangian frame of reference. The new contoured nozzle is found to produce higher particle velocities with greater radial spread; when operated at the same conditions/cost of operation as the commercial nozzle. These numerical results have shown the potential for extending cold spray to high density and low ductility particles by relatively minor rig modifications; through an effective synergy between gas dynamics and material science.

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THERMAL CHARACTERISTICS OF FOAMS AND DISCHARGE FROM FIRE-EXTINGUISHMENT FOAM SPRAY NOZZLE

Modern Physics Letters B ◽

10.1142/s021798490901845x ◽

2009 ◽

Vol 23 (03) ◽

pp. 381-384

Author(s):

YOUN-JEA KIM ◽

JIN-SOO PYO

Keyword(s):

Heat Flux ◽

Temperature Gradient ◽

Thermal Characteristics ◽

Expansion Ratio ◽

Experimental Results ◽

Orifice Diameter ◽

Spray Nozzle ◽

Foam Expansion ◽

Fire Extinguishment ◽

Air Hole

To evaluate the performance of discharged foam agents used to protect structures from heat and fire damages, the thermal characteristics of fire-extinguishment foams were experimentally investigated. Especially, two different parameters of a spray nozzle, that is, the number of air holes and the orifice diameter, were considered. A simple repeatable test for fire-extinguishment foams subjected to fire radiation was performed. Experimental results showed that the expansion ratio of the discharged foam with the small orifice throat ( d 0= 9.5 mm ) and opened air hole ( N h =9) was large. Results also showed that although the temperature gradient in the foam increased as the foam expansion ratio is increased, it remained constant as the intensity of heat flux increased.

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