A longitudinal magnetic field provides a new method for regulating the plasma velocity, pressure field, and temperature field of the TIG welding arc. However, the mechanism of action of the longitudinal magnetic field remains poorly understood. In order to address this problem, this paper develops a numerical model based on continuum mechanics. The mechanism of how magnetic field strength affects temperature, pressure field, plasma velocity, and potential was investigated. The geometric shape, temperature, pressure, and plasma velocity of the TIG welding arc under different magnetic fields were predicted. The results indicate that as magnetic field strength increases, the arc shape is compressed under the influence of magnetic forces, with the degree of compression increasing with magnetic field strength; plasma velocity gradually increases from 74 m/s at 0 mT to 296 m/s at 150 mT, but the velocity along the arc’s central axis first decreases and then increases with increasing magnetic field strength. As the magnetic field strength increases, a negative pressure first appears near the cathode, then expands toward the cathode, and finally toward the anode. During the expansion of the negative pressure, the maximum absolute value of the arc pressure increases by 12.72 times.

In this article, electrodeposited Ni-Al₂O₃ coatings were fabricated on the surface of a cylinder liner to enhance its corrosion resistance. The effect of current density on the surface morphology, phase structure, and corrosion resistance of the Ni-Al₂O₃ coatings was investigated using a scanning electron microscope (SEM), X-ray diffraction (XRD) instrument, and electrochemical workstation, respectively. The observed results show that a dense, flat morphology emerged on the surface of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm². Furthermore, among three Ni-Al₂O₃ coatings, the Al content of the one prepared under a current density of 3.5 A/dm² was the highest, with a value of 5.4 wt.%. XRD patterns demonstrated that the average nickel grain size of the Ni-Al₂O₃ coatings prepared at 3.5 A/dm² was only 251.6 nm, which was obviously smaller than those deposited under current densities of 2.5 A/dm² and 4.5 A/dm². Meanwhile, the adhesion strength of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm² was the largest, with a value of 40.9 N. Polarization curves indicated the corrosion potential of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm² was the highest, with a value of −0.42 V, while the corrosion current density of the coatings fabricated under a current density of 3.5 A/dm² was the lowest, with a value of 2.17 × 10⁻⁷ A/cm². In addition, the corrosive mass loss of Ni-Al₂O₃ coatings manufactured at 3.5 A/dm² was only 2.8 mg, illustrating excellent corrosion resistance. This study could enhance the service life and corrosion resistance of cylinder liners in internal combustion engines.