Basic principles and application potentials of cold gas spraying

In this review, the beginnings and evolution of the cold gas spray (CGS) technique are described, followed by the main fundamental aspects of the technique together with a description of the several spraying systems up to date. Sequentially, the main spray parameters and their influence on the properties of the coatings are reported. Afterwards, the most important methodologies for preparing the feedstock powders to be sprayed, the effect of the powder composition, microstructure, particle size and shape on the properties of the coatings are discussed. The nature of the spray gun and nozzle, and the substrate pre-treatments were also discussed. With regard to microstructure and properties, the chemical and physical characterization of the coatings and the performance in protecting the substrates against corrosion together with some mechanical properties are presented and compared. The lacking systematic studies about the great part of investigated systems is the main drawback to compare the published results. Closing this review, the main applications, and the potentialities of the CGS coatings are evidenced.

Download Full-text

Cold Gas Spraying of a High-Entropy CrFeNiMn Equiatomic Alloy

Coatings ◽

10.3390/coatings10010053 ◽

2020 ◽

Vol 10 (1) ◽

pp. 53 ◽

Cited By ~ 2

Author(s):

Joonas Lehtonen ◽

Heli Koivuluoto ◽

Yanling Ge ◽

Aapo Juselius ◽

Simo-Pekka Hannula

Keyword(s):

Stainless Steel ◽

Cross Section ◽

High Entropy Alloy ◽

Powder Feed Rate ◽

High Entropy ◽

Feed Pressure ◽

Process Gas ◽

Cold Gas Spraying ◽

Stainless Steel Coatings ◽

Cold Gas

Cold gas spraying was used to make a coating from an equiatomic CrFeNiMn high-entropy alloy. This four-component alloy was chosen because it is Co-free, thus allowing application in nuclear industries as a possible replacement of currently used stainless steel coatings. The feedstock material was gas atomized powder with a particle size distribution from 20 to 45 µm. A number of parameters were tested, such as the powder feed rate and gas feed pressure, in order to obtain as dense a coating as possible with nitrogen as the process gas. Spraying was performed using a gas preheating temperature of 1000 °C, gas feed pressure ranging from 50 to 60 bar, and two powder feeding rates. The coating thicknesses ranging from 230 to 490 µm and porosities ranging from 3% to 10% were obtained depending on the powder feed rate and gas feed pressure. The hardness of the cross-section of the coating was usually lower than that of the surface. The highest coating hardness obtained was above 300 HV0.3 for both the surface and the cross-section. The as-atomized powder consisted of a face-centered cubic (FCC) phase with a minute amount of body-centered cubic (BCC) phase, which was no longer detectable in the coatings. The microstructure of the coating was highly stressed due to the high degree of deformation occurring in cold gas spraying. The deformation leads to strain hardening and induces a pronounced texture in the coating. The {111} planes tend to align along the coating surface, with deformation and texturing concentrating mainly on particle boundaries. A high-entropy alloy (HEA) coating was successfully sprayed for the first time using nitrogen as a process gas. The coating has the potential to replace stainless steel coatings in nuclear industry applications.

Download Full-text

Tribological Properties of Cold Gas Spraying FeMnCrSi Alloy

10.31399/asm.cp.itsc2021p0616 ◽

2021 ◽

Author(s):

Rodolpho F. Vaz ◽

Sergi Dosta ◽

Irene G. Cano ◽

Anderson G.M. Pukasiewicz

Keyword(s):

High Pressure ◽

Wear Resistance ◽

Carbon Steel ◽

Coefficient Of Friction ◽

Sliding Wear ◽

Volume Loss ◽

Cold Gas Spraying ◽

Steel Substrates ◽

Disk Testing ◽

Cold Gas

Abstract FeMnCrSi and 316L alloy coatings were deposited on carbon steel substrates via high-pressure cold gas spraying and their microstructure, hardness, and wear resistance were obtained. Ball-on-disk testing (ASTM G99) was used to measure sliding wear behaviors. The mechanism of wear was found to be the same for both coatings, although FeMnCrSi had a higher coefficient of friction while 316L had less volume loss.

Download Full-text