Search Results for glow discharge emission

This article discusses the general principles, optical systems, and emission sources of optical emission spectroscopy for elemental analysis. Changes in the energy of the valence or outer shell electrons result in the atomic lines used in emission spectroscopy. Each possible combination of electron configurations produces a spectroscopic term that describes the state of the atom. Atomic emission is analytically useful only to the extent that the emission from one atomic species can be measured and its intensity recorded independent of emission from other sources. Emission sources are often designed to minimize molecular emission. Each of the four types of emission sources; arcs, high-voltage sparks, glow discharges, and flames; has a set of physical characteristics with accompanying analytical assets and liabilities. The article also discusses the applications of each type of emission source.

This article is a detailed account of optical emission spectroscopy (OES) for elemental analysis. It begins with a discussion on the historical background of OES and development trends in OES methods. This is followed by a description of the general principles and optical systems of OES, along with various types of emission sources commonly used for OES. Some of the processes involved in calibration and quantification of OES for direct solids analysis by the ratio method are then described. The article ends with a discussion on the applications of each type of emission sources.

The plasma carburizing process is basically a low-pressure carburizing process making use of a high-voltage electrical field applied between the load to be treated and the furnace wall producing activated and ionized gas species responsible for carbon transfer to the workpieces. This article begins with an overview of the theoretical background and the range and limitations of glow-discharge plasma. It describes the plasma carburizing process, which is carried out with methane or propane. Plasma carburizing processes of sinter metals and stainless steels, and the influence of current pulse length on carbon input of low-pressure carburizing process are also described. The article presents the basic requirements and process parameters to be considered in plasma carburizing equipment. It also exemplifies a still-working plasma process in industrial measure.

Plasma (ion) nitriding is a method of surface hardening using glow-discharge technology to introduce nascent (elemental) nitrogen to the surface of a metal part for subsequent diffusion into the material. This article describes the procedures and applications of plasma nitriding methods of steel. These methods include direct-current plasma nitriding, pulsed-current plasma nitriding, and active-screen plasma nitriding. The article reviews cold-walled and hot-walled furnaces used for plasma nitriding. It provides information on the importance of controlling three process parameters: atmosphere, pressure, and part temperature. The article includes a discussion on the influence of nitrogen concentration on case structure formation on nitrided steel, and explains the significance of microstructure, hardness, and fatigue strength on nitrided case. It also discusses processing, laboratory studies, and applications of nitrocarburizing of steel.

Sputtering is a nonthermal vaporization process in which the surface atoms are physically ejected from a surface by momentum transfer from an energetic bombarding species of atomic/molecular size. It uses a glow discharge or an ion beam to generate a flux of ions incident on the target surface. This article provides an overview of the advantages and limitations of sputter deposition. It focuses on the most common sputtering techniques, namely, diode sputtering, radio-frequency sputtering, triode sputtering, magnetron sputtering, and unbalanced magnetron sputtering. The article discusses the fundamentals of plasma formation and the interactions on the target surface. A comparison of reactive and nonreactive sputtering is also provided. The article concludes with a discussion on the several methods of process control and the applications of sputtered films.

This article discusses the principle, coil design, types and operation of a vacuum induction furnace. It describes the operation parameters that should be considered during the functioning of the induction furnace.

This article provides a brief account of glow discharge mass spectrometry (GDMS) for direct determination of trace elements in solid samples and for fast depth profiling in a great variety of innovative materials. It begins by describing the general principles of GDMS. This is followed by a discussion on the various components of a GDMS system as well as commercial GDMS instruments. A description of processes involved in specimen preparation and cleaning in GDMS is then presented. Various problems pertinent to multielemental calibrations in GDMS are discussed along with measures to overcome them. The article further provides information on the processes involved in the analytical setup of parameters in GDMS, covering the steps involved in the analysis of GDMS data. It ends with a section on the application and interpretation of GDMS in the metals industry.

Identification of alloys using quantitative chemical analysis is an essential step during a metallurgical failure analysis process. There are several methods available for quantitative analysis of metal alloys, and the analyst should carefully approach selection of the method used. The choice of appropriate analytical techniques is determined by the specific chemical information required, the condition of the sample, and any limitations imposed by interested parties. This article discusses some of the commonly used quantitative chemical analysis techniques for metals. The discussion covers the operating principles, applications, advantages, and disadvantages of optical emission spectroscopy (OES), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray spectroscopy, and ion chromatography (IC). In addition, information on combustion analysis and inert gas fusion analysis is provided.