Novel Fe-Based Amorphous Composite Coating with a Unique Interfacial Layer Improving Thermal Barrier Application

Abstract

To improve thermal barrier applications in advanced vehicle engines, a novel Fe-based amorphous composite coating was designed by introducing ceramic oxides and was prepared by atmospheric plasma spraying (APS). The microstructure and related properties of the as-deposited coating were investigated in detail. The composite coating comprises a well-formed FeCrNbBSi amorphous metallic matrix and dispersed yttria-stabilized zirconia (YSZ) splats. A unique Si-oxide interfacial layer with a thickness of several nanometers and an amorphous structure forms between the metallic matrix and ceramic phase, which is attributed to a combination of multiple effects. The composite coating displays extremely low thermal conductivity from 2.28 W/mK at 100 °C to 3.36 W/mK at 600 °C and can increase the surface temperature of the piston crown by 18.93 °C, which implies a significant means of enhancing the power efficiency. The improved thermal barrier ability of the composite coating is revealed as the crucial effect of the Si-oxide interfacial layer, which induces an increased interfacial thermal resistance. The fracture toughness of the composite coating remains at 3.40 MPa·m1/2, comparable to that of the monolithic amorphous coating, 3.74 MPa·m1/2, which is closely related to the formation of a Si-oxide layer and its nanoscale thickness. Therefore, the Fe-based amorphous composite coating developed here demonstrates great potential as an innovative metal-based thermal barrier coating for application in vehicle engines and provides specific inspiration for future works exploring the interfacial engineering of coating.

Long-Term Potentiodynamic Testing and Tribometric Properties of Amorphous Alloy Coatings under Saline Environment

“…The interface layer indicates that a good mechanical and metallurgical bond has developed between both the substrate and molten particles. Zhu et al proposed that the formation of nanoscale SiO 2 prevents the formation of interfacial imperfections and embrittlement issues and enables the coating to provide good fracture toughness [25]. Therefore, sandblasting was performed prior to the thermal spray process to achieve optimum surface roughness.…”

Numerical Analysis of High-Velocity Oxygen Fuel Thermal-Spray Process for Fe-Based Amorphous Coatings

“…Thermal spray technologies provide sufficient rapid cooling rates that inhibit longrange diffusion and avoid crystallization, existing as an alternate approach to beat scale disadvantages and increase the industrial applications of amorphous alloys. Many studies have attempted to manufacture Fe-based amorphous alloy coatings using various spraying methods, e.g., high-velocity oxygen fuel (HVOF) spraying [10,11], plasma spraying [12,13], laser cladding [14], and kinetic spraying [15]. Among these methods, HVOF spraying has attracted additional attention because of its benefits of low temperature and high velocity, which are conducive to manufacturing dense or low-porosity amorphous alloy coatings [16].…”

Effect of P Content on the Corrosion Behavior of Electrodeposited Fe-P Coatings

“…During the last decade, many attempts have been made for the deposition of Fe-based monolithic or composite coatings for use in different applications to extend the service life of materials working in corrosive, high temperature, and extreme environments. [1][2][3][4][5][6][7] Among different coating methods, the electrodeposition of Fe-P alloy coatings for application in different areas, such as anode material for rechargeable lithium batteries 8 and HER electrodes, 9 has attracted much attention. [10][11][12] These coatings have the potential to be used as eco-friendly candidates to replace hard chromium, Ni-P, and Co-Ni coatings.…”