Microstructure and thermal conductivity of wire-arc sprayed FeCrNbBSiC amorphous coating

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

“…A fraction of the α-Fe solid solution coexists with the amorphous matrix in both coatings as detected from the slightly extrusive crystalline diffraction peaks upon the broad halo basements. These general crystalline phases are independent of the ceramic additions, and their formation should be attributed to the insufficient glass-forming ability of FeCrNbBSi alloy and the nonuniformity of thermal sprayed coatings. , In addition, the major crystalline diffraction peaks in the composite coating are ascertained as the t’-ZrO 2 phase, which is in accordance with the phase structure of typical YSZ coatings. , The almost non-interfering character between the metallic and ceramic phases within the composite coating demonstrates the prevention of excessive reaction, which is attributed to the melting of individual in-flight particles and the subsequent rapid solidification of molten droplets, leading to the extremely limited interaction time of the two components. Reducing the influence of ceramic additions on the formation of the amorphous phase is important for maintaining the desired properties of the metallic matrix, because the devitrification process of metallic glasses is usually sensitive to the deviated composition or heterogeneous nuclei. , Therefore, this method of mechanically mixing the two powders and the nonequilibrium solidification characteristic of the APS process are responsible for the expected structure of the composite coating.…”

“…Averaged cycle values of the heat transfer coefficient and environmental temperature were adopted for the piston top and are listed in Figure . Other boundary conditions of heat exchange were used according to the method described in related literature. ,, In order to improve the feasibility and efficiency of the modeling, the thermal circuit method was used to model the heat transfer in the ring land and skirt region with the following assumptions: the effects of piston motion and ring twist on the heat transfer are neglected, the rings and skirt are fully engulfed in oil and there is no cavitation, and the conductive heat transfer in the oil film is neglected. ,, The average boundary convection coefficients and environmental temperatures predicted as the boundary conditions are given in Figure . This modeling process has been successfully applied by the steady-state thermal analyses of the piston to evaluate the effect of ceramic coating on the engine piston crown. , …”

“…The concept of MBTBCs greatly depends on the fundamental demand of low thermal conductivity, which deviates from the understanding of conventional metals, which are generally regarded as good conductors. Metallic glasses, accordingly, have come into sight owing to their high defect density originating from their disordered structure, which can scatter heat carriers intensively and result in abnormally low thermal conductivity. ,,− In this group, Fe-based amorphous alloys preferably satisfy engineering needs in view of their combination of a relatively high glass-forming ability and crystallization temperature, excellent wear resistance, and obvious cost efficiency. − Some Fe-based amorphous coatings prepared by high-frequency induction plasma spraying (IPS), high-velocity oxygen-fuel spraying (HVOF), atmospheric plasma spraying (APS), and wire-arc spraying (AS) present the expected low thermal conductivities in the range of 2–3 W/mK, − , thus making them proper candidates for MBTBCs.…”

“…1,2,6−8 In this group, Fe-based amorphous alloys preferably satisfy engineering needs in view of their combination of a relatively high glass-forming ability and crystallization temperature, excellent wear resistance, and obvious cost efficiency. 8−14 Some Fe-based amorphous coatings prepared by high-frequency induction plasma spraying (IPS), high-velocity oxygen-fuel spraying (HVOF), atmospheric plasma spraying (APS), and wire-arc spraying (AS) present the expected low thermal conductivities in the range of 2−3 W/mK, [1][2][3][4]15 thus making them proper candidates for MBTBCs.…”

Microstructure and Tribological Properties of Lubricating-Reinforcing Laser Cladding Composite Coating with the Ti2SC-Ti2Ni Mosaic Structure Phase

“…In recent years, laser cladding technology has been widely used in the preparation of wear-resistant and self-lubricating coatings on the surface of Ti6Al4V alloys as a new surface modification method [6,7]. Compared with other thermal deposition methods such as atmospheric plasma spraying (APS), flame spraying (FS), high-velocity oxygenfuel (HVOF), detonation spray coating (DSC), etc., laser cladding provides a superior metallurgical bonding with the substrate, which means less spalling or cracking behavior and denser coatings [8][9][10][11][12][13][14][15]. In the study of Zhou et al [16], self-lubricating anti-wear composite coatings were fabricated by laser cladding with Ni60/TiC/WS 2 mixed powders.…”