Amorphous Steel Coatings Deposited by Cold-Gas Spraying

Abstract

Cold-gas spray (CGS) deposition of amorphous steel coatings starting from a commercial feedstock powder containing boron, tungsten, and silicon was investigated. Microstructural characterization, carried out by X-ray diffraction (XRD), transmission electron microscopy, and backscattered electron diffraction (EBSD) analysis, confirmed the amorphous nature of deposited coatings. The amorphization phenomenon is related to high-strain/strain-rate deformation with shear instability caused by very high particle kinetic energy, with a mechanism that resembles the severe plastic deformation process. The CGS coatings were heat-treated at temperatures ranging from 650 to 850 °C to induce partial recrystallization. The effect of nanocrystal nucleation and growth on the hardness of the coatings was investigated, and the hardness of heat-treated samples was found to increase with respect to as-sprayed coatings, outperforming conventional high-velocity oxy-fuel (HVOF) deposits. Hardness was found to decrease after prolonged (<90 min) or higher temperature (>750 °C) exposures.

The Influence of the Powder Characteristics on 316L Stainless Steel Coatings Sprayed by Cold Gas Spray

“…Nowadays, CGS is accepted as a spray technique capable of depositing thick metal layers on different substrates at relatively low processing temperatures, maintaining the initial phase composition of different feedstock powders. Since the starting powders used in CGS remain in the solid state during the deposition, the most common defects of the high-temperature thermal spray processes, such phase transformation or oxidation, can be avoided [8][9][10][11].…”

Insights into the assessment of spreadability of stainless steel powders in additive manufacturing

“…Such that smaller droplets at 100% helium produce higher cooling rate and less solidification time since heat transfer is faster in these situations [37]. Particles atomised in lower cooling rate exhibit higher crystalline fraction and on the other hand particle atomised in a higher cooling rate show a higher amorphous fraction [31].Amorphous metals exhibit excellent mechanical properties and have greater wear and corrosion resistance due to the absence of grain boundaries compare to crystalline materials [38][39][40]. Metal Cooling rate also has influence on the coating properties of powders such that increased cooling rates improves the coating properties of powder batch [41].…”

Corrosion Resistance of Fe-Based Amorphous Films Prepared by the Radio Frequency Magnetron Sputter Method

“…It is reported that FeCrMoCB-Tm AAs have a high glass-forming ability [14][15][16][17][18][19] but high brittleness at room temperature, which greatly restricts their engineering applications. Thus, Fe-based AAs have been provided as powders for thermal spraying [20][21][22][23][24][25] against corrosion and wear for industrial applications [26][27][28].…”