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Inductively Coupled Plasma Optical Emission Spectrometry
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Only till more recently, other types of discharges, that is, plasmas, have been applied and used as atomization and excitation sources for OES. Technically speaking, a plasma is any form of matter (mostly gases) that is appreciably ionized, that is to say, a matter containing fraction (>1%) of electrons and positively charged ions together with neutral species, radicals, and molecules. The electrical plasmas used for analytical OES are highly energetic, ionized gases. They are normally created with inert gases, such as argon or helium. These plasma discharges are considerably hotter than traditional flames and furnaces, thus are used not only to breakdown almost any type of sample molecules but also to excite and/or ionize the free atoms for atomic and ionic emission. Currently, the state-of-the-art plasma is the argon supported ICP. Other plasmas include direct current plasma (DCP) and microwave induced plasma (MIP). Only the ICP will be discussed in this chapter.
Plasma nitriding of AISI M2 steel: performance evaluation in forming tools
Published in Surface Engineering, 2020
L. H. P. Abreu, M. C. L. Pimentel, W. F. A. Borges, T. H. C. Costa, M. Naeem, J. Iqbal, R. R. M. Sousa
Nitriding is a relatively economical thermochemical technique which can improve surface properties of several materials, including steels [3,4]. In the beginning, nearly a century ago, salt bath and gas nitriding systems were presented, which contain toxic chemicals and gases. Thus, those techniques were not feasible due to environmental threats and also require long treatment duration. As a result, such techniques were substituted by plasma nitriding, called as conventional plasma nitriding (CPN) or direct current plasma nitriding (DCPN). This technique is widely used for the improvement in tribological, mechanical properties and corrosion resistance of AISI M2 tool steel [5,6]. It involves the gases ionization due to the high potential difference among electrodes, and its working is based on the direct bombardment of ions on the sample surface, which is at cathodic potential [7].
Hollow cathodic plasma source nitriding of AISI 4140 steel
Published in Surface Engineering, 2021
Yang Li, Yongjie Bi, Minyi Zhang, Shangzhou Zhang, Xuepeng Gao, Zhehao Zhang, Yongyong He
Some models of ASPN have been reported in recent years; Corujeira Gallo and Dong [12] demonstrated that the mechanisms of the ASPN process were described by the ‘sputtering– deposition–decomposition–diffusion’ model. Partridge and co-workers [13] suggested that the nitrogen mass transfer is dominated by the sputtering deposition of iron nitride in the ASPN process. Saeed et al. [14] concluded that the ‘sputtering and re-condensation’ model for the nitrogen mass transfer mechanism in direct current plasma nitriding technology may be applicable in ASPN. The mechanism of nitriding mass transfer remains unclear [8]; this lack of mechanism hinders further development of the ASPN treatment.
Active screen plasma nitriding of laser powder bed fusion processed 316L stainless steel for the application of fuel cell bipolar plates
Published in Virtual and Physical Prototyping, 2023
Kaijie Lin, Jingchi Qiao, Dongdong Gu, Haoran Wang, Bo Shi, Wanli Zhang, Junhao Shan, Yong Xu, Linhai Tian
Active screen plasma nitriding (ASPN) is a surface modification technology based on glow discharge plasma and post-discharge plasma (Saeed et al. 2013). Different from traditional plasma nitriding, such as direct current plasma nitriding (DCPN) (Godec et al. 2020), the anode and cathode are connected with the shell and metal screen respectively, which enable the plasma to form only on the surface of metal screen rather than samples. Consequently, the limitations such as edge effect and hollow cathode effect caused by DCPN can be avoided. Our previous research separately applied ASPN and DCPN on 316L SS samples, and the microstructures and surface performances were investigated (Lin et al. 2014). Results revealed that ASPN process was able to avoid the precipitation of CrN, which was generated during DCPN, thus realising better corrosion resistance of 316L SS samples. Meanwhile, the surface properties (including surface conductivity and corrosion performance) of 316L SS were greatly improved after the ASPN process, which proved that ASPN was a promising surface modification method for 316L SS bipolar plates. However, there is no research on the modification of LPBF-processed components by the ASPN process. In this paper, ASPN was adopted to modify the surface of 316L SS processed by different LPBF parameters. The microstructures and surface properties of 316L SSs formed by different processes were investigated before and after ASPN. By comparing with wrought-316L SS, the dissolution and diffusion of nitrogen in atom-level structure, subgrain-level structure, grain-level structure and multilayer-level structure were discussed. And the ASPN modification mechanisms of LPBF-processed 316L SS, influenced by its hierarchically heterogeneous microstructures, were proposed.