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Electrostatics, Electrodynamics and Fluid Mechanics of Plasma
Published in Alexander Fridman, Lawrence A. Kennedy, Plasma Physics and Engineering, 2021
Alexander Fridman, Lawrence A. Kennedy
Eq. (6.52) for the diffusion coefficient across the strong magnetic field is similar to Eq. (4.122) for free diffusion without a magnetic field, but with the mean free path replaced by the Larmor radius. When the magnetic field is high and electrons are magnetized (ωB,i/νi << 1), then the electron Larmor radius is shorter than the electron mean free path (ρL << λe). Plasma diffusion across the strong magnetic field then is slower than without the magnetic field and decreases with the strength of the field.
Effect of Gradient Nanostructure on Plasma Sulfonitrocarburizing of 42MnCr52 Steel
Published in Tribology Transactions, 2020
X. H. Zhao, Y. Q. Zhao, D. S. Xu, C. H. Hu
42MnCr52 steel is widely used in the manufacture of parts such as oil casings and engine cylinder liners due to its good performance and low cost. However, 42MnCr52 steel is extremely prone to wear under harsh working environments, which can cause huge economic losses. In recent years, single plasma diffusion technology, such as plasma nitriding and low-temperature ion sulfurizing, has been extensively researched for the application in 42MnCr52 steel and other materials. Plasma nitriding can improve the friction and corrosion properties (Podgornik, et al. (1); Nouveau, et al. (2)) and enhance the hardness (Wang, et al. (3)) of materials. However, embrittlement and flaking often occur (Kulka, et al. (4)). Low-temperature ion sulfurizing can form a sulfide layer containing an FeS phase, which not only can reduce the friction coefficient (COF) but also can avoid adhesive wear due to its excellent solid lubrication capability (Ma, et al. (5)). Materials for low-temperature ion sulfurizing include AISI L6 steel (Wang, et al. (6)), high-speed steel (Wang, et al. (7)), 1Cr18Ni9Ti steel (Wang, et al. (8)), and 1045 steel (Zhang, et al. (9)). However, the sulfide layer needs a hard subsurface layer to provide effective support for strong wear resistance (Cai, et al. (10)). Single plasma diffusion technology still has some limitations, such as poor fracture toughness, the low binding force and low hardness of the subsurface layer, etc. In this case, plasma composite diffusion technology (a combination of two or several plasma diffusion techniques) has gradually become the focus of research, including plasma carbonitriding (Shen, et al. (11)), plasma nitriding–sulfurizing (Wang, et al. (12)), and plasma nitrocarburizing and sulfurizing (Hu, et al. (13)). Plasma sulfonitrocarburizing (PSNC) as a composite diffusion technique has great industrial significance because it can form an anti-attrition composite structure with a soft surface (sulfide layer) and a hard subsurface (nitrocarburized compound layer).