Microstructure and mechanical properties of twin-wire arc sprayed Ni-Al composite coatings on 6061-T6 aluminum alloy sheet

Guo

et al. 2019

Droplet atomization characteristics and its morphology in twin-wire arc sprayed (TWAS) Ni-Al were explored in depth. Both numerical model and theoretical method were built for calculating the process of the droplet deformation and breakup in air flow, which based on the standard k-ε model and the volume of fluid (VOF) dual-phase flow model. The atomization characteristics of double droplets and three droplets were also studied in the atomization process by simulation. The micro structure and the morphology of the composite coatings were analyzed by SEM and TEM. The experimental results indicate that TWAS droplets are the process of explosive breakup or two steps breakup. Morphology of the TWAS prepared Ni-20wt.%Al and Ni-5wt.%Al particles was accordingly characterized by SEM. The phase compositions of the Ni-Al particles were obtained by EDS. By testing the velocity of sprayed particles, the change rule of particles with spray pressure was obtained. Ni twins are discovered in the Ni-Al coating due to rapid cooling in TWAS process.

Section: Characteristics and Morphologies Of Particles In Twas Ni-almentioning

confidence: 99%

Atomization Characteristics of Droplet and Morphologies of Arc Sprayed Ni-Al Particles and Composition Coatings

Guo

et al. 2019

“…Figure 14a is the laser confocal microscope to observe the surface morphology, Figure 14b is the SEM morphology, Figure 14c and Figure 14d are the microscope to observe the roughness and three-dimensional morphology of the coating respectively. There are no cracks on the coating surface, and it is uneven and roughness is larger 21,22 . It can be seen from Figure 15 and Table 4 that the average surface roughness is 24.688 μm.…”

Section: Surface Roughness Of Ni-al Coatingsmentioning

confidence: 99%

Deformation and Solidification Characteristics and Microstructure of Arc Sprayed Ni-Al Composition Coatings

Guo

et al. 2019

Droplets deformation and solidification characteristics in twin-wire arc sprayed Ni-Al were explored in depth. Both theoretical method and numerical model were established for calculating the deformation process of the droplets impacting on the substrate and their solidification behavior in airflow, which based on two models of the volume of fluid (VOF) dual-phase flow and the standard k-ε. The morphology and the microstructure of the composite coatings were analyzed by XRD, SEM and TEM. The results of the experiment indicate the droplets cooling rate ranges from 3.0×10 7 to 7.5×10 7 K/s. The main components of Ni-5wt.% Al coating were Ni solid solution, and a small number of Ni 3 Al 4 , Al 2 O 3 and NiO. The main phases of Ni-20wt.% Al coating are Ni 3 Al and NiAl. EDS and TEM analysis shows that there are a few amorphous and equiaxed crystals in the Ni-Al coating. The surface roughness increases with the decrease of spraying pressure and spraying distance.

“…Generally, the Ni-Al powder under different technological parameters is mostly collected by using water. Processing parameters for the Ni-Al powders are listed in Table 3 19,20 . The obtained Ni-Al powder is precipitated for final collection, closed and under 373 K drying for 2 h. The surface and cross-section morphology of Ni-Al powder is observed by SEM.…”

Section: Characteristics Of Powder and Microstructure Of Ni-al Coatingsmentioning

confidence: 99%

“…The specimens of sand blasting should not be placed more than 4 h before spraying. Related sandblast parameters before arc spraying are listed in Table 4 19,20 . Processing parameters of twin-wire arc spraying are listed in Table 5 19,20 .…”

Section: Characteristics Of Powder and Microstructure Of Ni-al Coatingsmentioning

confidence: 99%

Microstructure and Flight Behaviors of Droplet and its Solidification in Twin-Wire Arc Sprayed Ni-Al Composite Coatings

Liu

et al. 2018

Droplet flight and solidification behaviors during twin-wire arc sprayed (TWAS) composite coatings were systematically investigated. Both theoretical model and numerical method were established for calculating the droplet deformation, breakup and solidification process in air flow based on the volume of fluid (VOF) dual-phase flow model jointed with the standard k-ε model. The experimental simulation results indicate that TWAS droplet is broken through explosion or two steps breaking process. The calculation of TWAS gas flight dynamics demonstrates that the TWAS particles are accelerated at first and then slowed down. Microstructure of the TWAS prepared Ni-5wt.%Al and Ni-20wt.%Al composite coating was accordingly characterized by XRD, SEM and TEM, so the phase compositions of the Ni-Al composite coatings were obtained. TEM analysis also showed that an amorphous phase was formed according to the characteristic of diffraction ring in Ni matrix solid solution at an original state.