scholarly journals Some Material Characteristics of Cold-Sprayed Structures

2007 ◽  
Vol 2007 ◽  
pp. 1-3 ◽  
Author(s):  
Victor K. Champagne ◽  
Dennis J. Helfritch ◽  
Matthew D. Trexler
Keyword(s):  
Strain Hardening ◽  
Model Calculation ◽  
Metal Powder ◽  
Impact Velocity ◽  
Cold Spray ◽  
High Velocity ◽  
Cold Spraying ◽  
Metal Powders ◽  
Rocket Nozzle ◽  
Powder Particles

The deposition and consolidation of metal powders by means of cold spray are methods whereby powder particles are accelerated to high velocity through entrainment in a gas undergoing expansion in a rocket nozzle and are subsequently impacted upon a surface. The impacted powder particles form a consolidated structure which can be several centimeters thick. The characteristics of this structure depend on the initial characteristics of the metal powder and upon impact velocity. The influence of impact velocity on strain hardening and porosity are examined. A materials model is proposed for these phenomena, and model calculation is compared with experiment for the cold spraying of aluminum.

scholarly journals Fabrication and microstrain evolution of Al-TiB2 composite coating by cold spray deposition

2017 ◽  
Vol 233 (6) ◽  
pp. 1044-1052 ◽  
Author(s):  
H Chen ◽  
Z Pala ◽  
T Hussain ◽  
DG McCartney
Keyword(s):  
Composite Coating ◽  
Cold Spray ◽  
Spray Deposition ◽  
Composite Coatings ◽  
Cold Spraying ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Micro Cracks ◽  
Powder Particles

This paper investigates the microstructure evolution of Al-TiB2 coatings prepared by cold spraying. In situ Al-TiB2 composite powders containing uniformly distributed titanium diboride (TiB2) particles with a size range of 5–100 nm in the Al matrix and Al/Al-TiB2 blended powders were used as the cold spray feedstock for coating fabrication on aluminium alloy substrates. The microstructures of the feedstock powders and as-deposited coatings were characterised using scanning electron microscopy with energy dispersive X-ray analysis and X-ray diffraction. Al/Al-TiB2 blended powder coatings, compromising closely packed powder particles, were sprayed to an approximate thickness of 500 µm. Al-TiB2 composite coatings (approximately 50 µm thick) were obtained retaining the microstructure of the composite powders being sprayed and no evidence of detrimental phase transformation was found. However, micro-cracks were found to exist in the Al-TiB2 coating due to the hardly deformable powder particles. Little or no microstrain was revealed in the as-sprayed Al-TiB2 coating, indicating that annealing may have occurred due to the localised adiabatic heating during the spraying process. It is demonstrated that it is possible to fabricate the Al-TiB2 composite coating by cold spray deposition but further improvements to eliminate coating cracking are required.

scholarly journals Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4182
Author(s):  
Alan Wilmański ◽  
Magdalena Zarzecka-Napierała ◽  
Zbigniew Pędzich
Keyword(s):  
Combustion Synthesis ◽  
Metal Powder ◽  
Weight Ratio ◽  
Nitrogen Pressure ◽  
Alumina Powder ◽  
Metal Powders ◽  
Aluminum Oxynitride ◽  
Synthesis Conditions ◽  
Aluminum Metal ◽  
Loose Powder

This paper describes combusting loose powder beds of mixtures of aluminum metal powders and aluminum oxide powders with various grain sizes under various nitrogen pressure. The synthesis conditions required at least 20/80 weight ratio of aluminum metal powder to alumina powder in the mix to reach approximately 80 wt% of γ-AlON in the products. Finely ground fused white alumina with a mean grain size of 5 μm was sufficient to achieve results similar to very fine alumina with 0.3 μm grains. A lower nitrogen pressure of 1 MPa provided good results, allowing a less robust apparatus to be used. The salt-assisted combustion synthesis upon addition of 10 wt% of ammonium nitrite resulted in a slight increase in product yield and allowed lower aluminum metal powder content in mixes to be ignited. Increasing the charge mass five times resulted in a very similar γ-AlON yield, providing a promising technology for scaling up. Synthesis in loose powder beds could be utilized for effective production of relatively cheap and uniform AlON powder, which could be easily prepared for forming and sintering without intensive grounding and milling, which usually introduce serious contamination.

Investigation of the Splat Deposition Behavior onto a Composite Coating in Cold Spray

2018 ◽  
Vol 941 ◽  
pp. 1639-1644
Author(s):  
Xin Chu ◽  
Phuong Vo ◽  
Stephen Yue
Keyword(s):  
Electron Microscope ◽  
Composite Coating ◽  
Cold Spray ◽  
Spray Deposition ◽  
Cold Spraying ◽  
Single Component ◽  
Optical Profilometry ◽  
Deposition Behavior ◽  
Polished Substrate ◽  
Scanning Electron

The splat test is usually generated by low feed rate cold spraying of particles onto an as-polished substrate and it can be considered as a monolayer coating deposition. In this study, in order to investigate cold spray deposition mechanisms, Fe splats were sprayed onto the cold-sprayed single component 316L, Fe, and a composite 90Fe coatings. Results showed that although there is only 3.6 vol.% of 316L in the composite 90Fe coating, Fe splats exhibit a much better deposition behavior onto the 90Fe as compared with the single component Fe coating. To explain this observation, Fe splat samples were characterized using the scanning electron microscope (SEM), optical profilometry, splat adhesion tests, and splat nanoindentation. Finally, a preliminary explanation towards the Fe splat deposition behavior onto the composite coating was drawn.

Microstructure and Mechanical Properties of the Wide-Gap Region Brazed with Various Powder Mixing Ratios of Additive to Filler Metal Powders

2006 ◽  
Vol 118 ◽  
pp. 479-484 ◽  
Author(s):  
Yong Hwan Kim ◽  
S.I. Kwun
Keyword(s):  
Mechanical Properties ◽  
Metal Powder ◽  
Room Temperature ◽  
Filler Metal ◽  
Metal Powders ◽  
Powder Mixing ◽  
Factors Affecting ◽  
Mixing Ratios ◽  
Microstructure And Mechanical Properties ◽  
Wide Gap

This study investigated the microstructure and mechanical properties of the wide-gap region brazed with various powder mixing ratios of additive powder (IN738) to filler metal powder (DF4B). The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1230°C for 1 hr. The microstructure of the brazed region was analyzed by FESEM and AES. The wide-gap region brazed with 60wt.% IN738 additive powder and 40 wt.% DF 4B filler metal powder had a microstructure consisting of Ni solid solution + γ' and (Cr, W)2B. The fracture strength of the wide-gap region brazed with 60 wt.% IN738 additive and 40 wt.% DF 4B powder was as high as 832 MPa at room temperature. It was found that the (Cr, W)2B and pores in the brazed region are important microstructural factors affecting the mechanical properties of the wide-gap brazed region.

Cold spray micro-defects and post-treatment technologies: a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wang Zhizhong ◽  
Han Chao ◽  
Guosheng Huang ◽  
Han Bin ◽  
Han Bin
Keyword(s):  
Cold Spray ◽  
Influence Factors ◽  
Cold Spraying ◽  
Post Treatment ◽  
Treatment Technology ◽  
Treatment Methods ◽  
Content Type ◽  
Treatment Technologies ◽  
Single Method ◽  
Improved Performance

Purpose The deposition of particles onto a substrate during the cold spraying (CS) process relies on severe plastic deformation, so there are various micro-defects induced by insufficient deformation and severe crushing. To solve the problems, many post-treat techniques have been used to improving the quality by eliminating the micro-defects. This paper aims to help scholars and engineers in this field a better and systematic understand of CS technology by summarizing the post-treatment technologies that have been investigated recently years. Design/methodology/approach This review summarizes the types of micro-defects and introduces the effect of micro-defects on the properties of CS coating/additive manufactured, illustrates the post-treatment technologies and its effect on the microstructure and performances, and finally outlooks the future development trends of post-treatments for CS. Findings There are significant discoveries in post-treatment technology to change the performance of cold spray deposits. There are also many limitations for post-treatment methods, including improved performance and limitations of use. Thus, there is still a strong requirement for further improvement. Hybrid post-treatment may be a more ideal method, as it can eliminate more defects than a single method. The proposed ultrasonic impact treatment could be an alternative method, as it can densify and flatten the CS deposits. Originality/value It is the first time to reveal the influence factors on the performances of CS deposits from the perspective of microdefects, and proposed corresponding well targeted post-treatment methods, which is more instructive for improving the performances of CS deposits.

Parametric Redesign of a Convergent-Divergent Cold Spray Nozzle

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.

scholarly journals Particle Compression Test: A Key Step towards Tailoring of Feedstock Powder for Cold Spraying

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 458 ◽  
Author(s):  
Hamid Assadi ◽  
Frank Gärtner
Keyword(s):  
Cold Spray ◽  
Cold Spraying ◽  
Compression Tests ◽  
Feedstock Powder ◽  
Design And Manufacturing ◽  
Present Case Study ◽  
Force Displacement ◽  
Subsequent Comparison ◽  
The Ideal

Cold spray is on the way to becoming a mainstream technology for coating and additive manufacturing processes. While there have been many advances in various aspects of this technology, the question of tailoring the ‘ideal’ feedstock powder for cold spraying has remained open. In particular, the mechanical strength and its dependence on the particle size, which are amongst the most relevant properties of the feedstock powder for cold spraying, are rarely covered when reporting powder specifications. This is mainly because of the lack of standardised methods of characterisation for these specific properties. In the present case study, we demonstrate how compression tests of single Inconel 718 particles by using a modified nanoindenter can address this central question. Data analyses are supported by finite element modelling of particle compression for a range of plastic behaviours. The results of simulation are then stored in the form of a surrogate model for subsequent comparison with the experimental data. Thus, the ultimate tensile strength and the size of the examined particles are calculated directly from the measured force-displacement data. The paper will also discuss how this information can be used to optimise cold spraying, and so, unveils a key step towards the design and manufacturing of cold-spray-specific feedstock powder.

scholarly journals Influence of Cold Spray Nozzle Displacement Strategy on Microstructure and Mechanical Properties of Cu/SiC Composites Coating

2019 ◽  
Vol 813 ◽  
pp. 110-115
Author(s):  
Olga Matts ◽  
Hussein Hammoud ◽  
Alexey Sova ◽  
Zineb Bensaid ◽  
Guillaume Kermouche ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Cold Spray ◽  
Vertical Direction ◽  
Cold Spraying ◽  
Traverse Speed ◽  
Deformation Pattern ◽  
Spray Nozzle ◽  
Particle Deformation ◽  
Compressive Tests

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.

Characteristic Analysis of the Stress Propagation of Metal Powder in High Velocity Compaction Using DEM

2020 ◽  
Vol 89 (4) ◽  
pp. 044602
Author(s):  
Wei Zhang ◽  
Kun Liu ◽  
Jian Zhou ◽  
Rongxin Chen ◽  
Ning Zhang ◽  
...  
Keyword(s):  
Metal Powder ◽  
High Velocity ◽  
Characteristic Analysis ◽  
Stress Propagation ◽  
High Velocity Compaction
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