scholarly journals Wear and Fretting Behavior of Cold Sprayed IN625 Superalloy

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 49
Author(s):  
Pasquale Daniele Cavaliere ◽  
Antonella Rizzo ◽  
Daniele Valerini ◽  
Laura Capodieci
Keyword(s):  
Weight Loss ◽  
Cold Spray ◽  
Maximum Load ◽  
Damage Mechanisms ◽  
Spray Coatings ◽  
Coating Surface ◽  
Triaxial Stresses ◽  
Scratch Tests ◽  
Maximum Stresses

The wear and fretting behaviour of IN625 cold spray coatings was analysed and the results are presented. The cold spray conditions were selected in order to obtain coatings with minimum porosity and maximum particles splat. This leads to compact and hard deposited material able to resist wear damaging and to dissipate energy during fretting. The coating’s strength was evaluated through nanoindentation that revealed an increased hardness from the surface toward the substrate. This different hardening behaviour from the coating surface toward the substrate leads to increased resistance to fretting and wear as the maximum stresses increase. This was revealed by scratch tests performed at linearly increasing loads that allowed identifying of the damage mechanisms acting on the coating as the triaxial stresses increase. The hardening behaviour of the coating also influenced the fretting behaviour revealed by the weight loss experienced by varying the fretting maximum load.

Optimization of laser cladding of cold spray coatings with B4C and Ni powders

2017 ◽  
Author(s):  
V. M. Fomin ◽  
A. A. Golyshev ◽  
A. G. Malikov ◽  
A. M. Orishich ◽  
A. A. Filippov ◽  
...  
Keyword(s):  
Cold Spray ◽  
Laser Cladding ◽  
Spray Coatings

Micro-Porous Coatings and Enhanced CHF for Downward Facing Boiling During Passive Emergency Reactor Cooling

2016 ◽  
Author(s):  
Albert E. Segall ◽  
Faruk A. Sohag ◽  
Faith R. Beck ◽  
Lokanath Mohanta ◽  
Fan-Bill Cheung ◽  
...  
Keyword(s):  
Cold Spray ◽  
Heat Removal ◽  
Porous Coating ◽  
Porous Coatings ◽  
Spray Coatings ◽  
Spray Process ◽  
External Cooling ◽  
Loss Of Coolant Accident ◽  
Lower Head ◽  
Viable Approach

During a Reaction Initiated Accident (RIA) or Loss of Coolant Accident (LOCA), passive external-cooling of the reactor lower head is a viable approach for the in-vessel retention of Corium; while this concept can certainly be applied to new constructions, it may also be viable for operational systems with existing cavities below the reactor. However, a boiling crisis will inevitably develop on the reactor lower head owing to the occurrence of Critical Heat Flux or CHF that could reduce the decay heat removal capability as the vapor phase impedes continuous boiling. Fortunately, this effect can be minimized for both new and existing reactors through the use of a Cold-Spray delivered, micro-porous coating that facilitates the formation of vapor micro-jets from the reactor surface. The micro-porous coatings were created by first spraying a binary mixture with the sacrificial material then removed via etching. Subsequent quenching experiments on uncoated and coated hemispherical surfaces showed that local CHF values for the coated vessel were consistently higher relative to the bare surface. Moreover, it was observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit varied appreciably along the outer surface. Nevertheless, the results of this intriguing study clearly show that the use of Cold Spray coatings could enhance the local CHF limit for downward facing boiling by more than 88%. Moreover, the Cold-Spray process is amenable to coating the lower heads of operating reactors.

The Elastic Modulus of Cold Spray Coatings: Influence of Inter-splat Boundary Cracking

2013 ◽  
Vol 22 (8) ◽  
pp. 1348-1357 ◽  
Author(s):  
G. Sundararajan ◽  
Naveen M. Chavan ◽  
S. Kumar
Keyword(s):  
Elastic Modulus ◽  
Cold Spray ◽  
Spray Coatings ◽  
Splat Boundary

Laboratory-based study of novel antimicrobial cold spray coatings to combat surface microbial contamination

2020 ◽  
Vol 41 (12) ◽  
pp. 1378-1383 ◽  
Author(s):  
M.D.I. Lucas ◽  
I. Botef ◽  
R. G. Reid ◽  
S. F. van Vuuren
Keyword(s):  
Cold Spray ◽  
Silver Powder ◽  
Exposure Period ◽  
Microbial Reduction ◽  
Surface Coatings ◽  
Antimicrobial Efficacy ◽  
Contact Period ◽  
Bacterial Reduction ◽  
Spray Coatings ◽  
Time Kill

AbstractObjective:To investigate the touch-contact antimicrobial efficacy of novel cold spray surface coatings composed of copper and silver metals, regard to their rate of microbial elimination.Design:Antimicrobial time-kill assay.Setting:Laboratory-based study.Methods:An adapted time-kill assay was conducted to characterize the antimicrobial efficacy of the developed coatings. A simulated touch-contact pathogenic exposure to Gram-positive Staphylococcus aureus (ATCC 25923), Gram-negative Pseudomonas aeruginosa (ATCC 27853), and the yeast Candida albicans (ATCC 10231), as well as corresponding resistant strains of gentamicin-methicillin–resistant S. aureus (ATCC 33592), azlocillin-carbenicillin–resistant P. aeruginosa (DSM 46316), and a fluconazole-resistant C. albicans strain was undertaken. Linear regression modeling was used to deduce microbial reduction rates.Results:A >7 log reduction in microbial colony forming units was achieved within minutes on surfaces with cold spray coatings compared to a single log bacterial reduction on copper metal sheets within a 3 hour contact period. Copper-coated 3-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) achieved complete microbial elimination against all tested pathogens within a 15 minute exposure period. Similarly, a copper-on-copper coating achieved microbial elimination within 10 minutes and within 5 minutes with the addition of silver powder as a 5 wt% coating constituent.Conclusions:In response to the global need for alternative solutions for infection control and prevention, these effective antimicrobial surface coatings were proposed. A longitudinal study is the next step toward technology integration.

Study of Damage Mechanisms in Cold-Sprayed 316L-Matrix Composite Coatings Using Novel Impact-Sliding Testing

2014 ◽  
Vol 922 ◽  
pp. 452-462 ◽  
Author(s):  
R. Maestracci ◽  
N. Fabrègue ◽  
M. Jeandin ◽  
G. Bouvard ◽  
M. Messaadi ◽  
...  
Keyword(s):  
Cold Spray ◽  
High Performance ◽  
Composite Coatings ◽  
Industrial Applications ◽  
Damage Mechanisms ◽  
Coating Composition ◽  
Before And After ◽  
Coating Microstructure ◽  
Service Conditions ◽  
Sliding Test

Cold spray is now well recognized as one of the most powerful and efficient coating process because it is cost-attractive and “green”. However, this process still shows limitations to achieve coatings for highly-demanding service conditions such as those required in certain automotive and/or aircraft applications. Beyond these limitations, cold spray is expected to compete with conventional P/M routes.The present work therefore focussed on the study of damage mechanisms in cold-sprayed AISI 316L and 316L-matrix–Cu composites coatings due to high-loading conditions. Different damage mechanisms could occur depending on the content of Cu particle addition, due to changes in the response of the microstructure to the loading. These mechanisms were studied using the newly-developed “impact-sliding” test. In this test, a steel ball impacts the coating surface at a given frequency, with a fixed angle. The influence of major testing parameters was investigated.Microstructures before and after testing were studied using optical microscopy, scanning electron microscopy (SEM), and microprobe analysis in addition to 3D optical profilometry of impacted areas. Damage mechanisms were seen to be of two types, i.e. plastic deformation and wear. These resulted in decohesion of splats, formation of wear debris and formation of a layer with a tribologically-transformed structure (TTS) at the contact surface.Results showed that cold spray could be claimed to be suitable for the achievement of high-performance coatings for industrial applications provided that the coating microstructure can be controlled. This could be done using a composite approach to the coating composition.

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