Airflow Dynamics and Aluminum Coating Oxidation Behavior under Electric-Arc Spraying with Airflow Pulsations

Abstract

The paper aims to investigate the airflow dynamics of electric-arc spraying (EAS) with airflow pulsation. The study is focused on the dynamic structure of the airflow with an obstacle in the form of crossed electrodes at the steady and the pulsating air supply (with a frequency up to 120 Hz). The work was fulfilled using a computer simulation, the airflow “shadow” photo visualization, and the microstructure characterization of the coatings formed. It was found that when air flows along the crossed electrodes with a gap of 2 mm, a depression zone appears in the flow with a pressure drop from 0.56 MPa to 0.01 MPa. The air pulsation resulted in a change in a flow’s dynamic structure towards an increase in the length of the depression zone, which covers most of the arc, affecting the liquid metal oxidation. It is established that the frequency of a droplet formation should match the frequency of the airflow pulsation to minimize the metal oxidation. With the air pulsating at about 65 Hz, the oxide volume fraction in the aluminum coating was reduced by 3.6 times compared to the steady airflow. EAS with airflow pulsation has the potential for technological cost reduction.

An overview of additively manufactured metal matrix composites: preparation, performance, and challenge

“…Both techniques employ composite powder as feedstock to fabricate MMC components. Thermal spraying methods use the flame, electric arc, or plasma arc as heat sources and spray the powder in a semi-molten state in high-speed gases [108][109][110]. The temperature of the high-speed gases ranges from 1500 • C to 15 000 • C, depending on the heat sources used [108,110].…”

“…Thermal spraying methods use the flame, electric arc, or plasma arc as heat sources and spray the powder in a semi-molten state in high-speed gases [108][109][110]. The temperature of the high-speed gases ranges from 1500 • C to 15 000 • C, depending on the heat sources used [108,110]. Cold spraying employs a high-pressure supersonic gas jet to propel powder particles at or surpass a critical velocity range of 500-1200 m•s −1 to fabricate components [111].…”

ПОРІВНЯЛЬНИЙ АНАЛІЗ КОРОЗІЇ В КИСЛОТАХ ІКОСАЕДРИЧНИХ І ДЕКАГОНАЛЬНИХ КВАЗІКРИСТАЛІВ У СПЛАВАХ НА ОСНОВІ Al

“…Зазвичай, корозійні властивості залежать від хімічного складу та мікроструктури сплавів [7][8][9][10]. Відкриття квазікристалів створює нові можливості для розробки корозійнотривких покриттів [11][12][13][14]. Квазікристали відносять до нового класу матеріалів, які мають аперіодичний кристалографічний порядок [15][16][17].…”

“…Квазікристалічні сплави на основі Al виплавляли в наступних концентраційних діапазонах (в ат. %): сплави Al-Cu-Fe -Al (63-65), Cu (24)(25), Fe (11)(12); сплави Al-Cu-Co -Al (63-65), Cо (20)(21)…”

Numerical modeling of two‐phase flows in the presence of dynamic and thermal interactions

“…In addition to the processes occurring in gaseous media (compressibility, turbulence, chemical reactions, etc. ), there are additional mechanisms of intercomponent and especially interphase interactions that accompany the motion of these media (i.e., phase transitions, momentum and energy exchange, chaotic motion, particle rotation, and collision) 9–11 . The additional complexity of the problem in question is related to the incompleteness of turbulence theory and the specific features of interactions between phases and turbulent currents in the presence of chemical reactions, consisting of the extremely complex nature of the mutual influence of turbulent transport processes and chemical reaction processes.…”