Search Results for energy

Low-energy ion-scattering spectroscopy (LEISS) is used extensively to analyze solid surfaces. The LEISS process relies on binary elastic collisions between an incident ion beam and the atoms in a sample to obtain information on the surface atoms. The velocity of the scattered ions is used to determine the mass of the atoms that are struck. This article introduces LEISS and its principles. It describes the use of LEISS spectra in qualitative and quantitative analyses, and reviews the instrumentation and applications of LEISS.

Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article describes the principles of diffraction from surfaces, and elucidates the method of sample preparation to achieve diffraction patterns. The article describes the limitations of surface sensitive electron diffraction and discusses the applications of LEED with examples.

The use of renewable energy has grown strongly in all end-use sectors such as power, heat, and transport. This article describes thermal spray applications that improve efficiency, lower maintenance costs, and prolong operational life in the renewable energy technologies, including wind power, hydro power, biomass and biofuels, solar energy, and fuel cells.

This article discusses the principles of operation, capabilities, and limitations of the thermal energy method of deburring, with illustrations.

Batteries and fuel cells are popular forms of portable electrical energy sources. This article discusses the operation and corrosion problems inherent in batteries and fuel cells. Batteries are classified into two groups: primary or nonrechargeable batteries and secondary or rechargeable batteries. Fuel cells are classified into five types: phosphoric acid fuel cell (PAFC), solid polymer electrolyte fuel cell, alkaline electrolyte fuel cell, molten carbonate fuel cell (MCFC), and solid oxide fuel cell. The article presents reactions that occur during charging and discharging of lead-acid batteries, PAFCs, and MCFCs.

This article describes the corrosion modes in a waste-to-energy boiler. It discusses the corrosion protection and alloy performance with an emphasis on two main areas of the boiler: furnace water walls and super heaters.

This article provides a history of electron and laser beam welding, discusses the properties of electrons and photons used for welding, and contrasts electron and laser beam welding. It presents a comparison of the electron and laser beam welding processes. The article also illustrates constant power density boundaries, showing the relationship between the focused beam diameter and the absorbed beam power for approximate regions of keyhole-mode welding, conduction-mode welding, cutting, and drilling.

Induction processes for melting and heating of metals belong to the high-energy-consuming industrial processes, and continuous improvement of energy efficiency of competitive melting and heating technologies is of increasing interest. This article discusses the energy demand of various melting processes and the improvements in the efficiency of melting processes in induction crucible furnaces. It provides energetic and ecological comparisons of different furnaces for melting of cast iron and aluminum. The article also describes the energy and power management of induction melting processes.

Surface modification is the alteration of the surface composition or structure using energy or particle beams. This article discusses two different surface modification methods. The first, ion implantation, is the introduction of ionized species into the substrate using kilovolt to megavolt ion accelerating potentials. The second method, laser processing, is high-power laser melting with or without mixing of materials precoated on the substrate, followed by rapid melt quenching. The article also describes the advantages and disadvantages of the surface modification approach to promote corrosion resistance.

Welding and joining processes are essential for the development of virtually every manufactured product. This article discusses the fundamentals of fusion welding processes, with an emphasis on the underlying scientific principles. It reviews the role of energy-source intensity and the width of the heat-affected zone in fusion welding processes. The article contains figures from which the properties of any heat source can be estimated readily.

Fusion-based additive manufacturing (AM) processes rely on the formation of a metallurgical bond between a substrate and a feedstock material. Energy sources employed in the fusion AM process include conventional arcs, lasers, and electron beams. Each of these sources is discussed, with an emphasis on their principles of operation, key processing variables, and the influence of each source on the transfer of heat and material. Common energy sources used for metals AM processes, particularly powder-bed fusion and directed-energy deposition, are also discussed. Brief sections at the end of the article discuss the factors dictating the choice of each of these energy sources and provide information on alternative sources of AM.

This article presents a detailed account of directed-energy deposition (DED) processes that are used for additive manufacturing (AM) of metallic materials. It begins with a process overview and a description of the components of DED systems followed by sections providing information on the process involved in DED and the materials used for DED. The postprocessing applied to the material after deposition is then covered. The article discusses the properties of metallic materials produced by using DED and ends with a discussion on applications for DED processes in various industries.

Directed-energy deposition (DED) is a kind of additive manufacturing (AM) technology based on synchronous powder feeding or wire feeding. This article provides a comprehensive coverage of DED for ceramic AM, beginning with an overview of DED equipment setup, followed by a discussion on DED materials and the DED deposition process. The bulk of the article is devoted to the discussion on the microstructure and properties of oxide ceramics, namely alumina and zirconia ceramics.

This article covers in-line process monitoring of the metal additive manufacturing (AM) methods of laser and electron beam (e-beam) powder-bed fusion (PBF) and directed-energy deposition (DED). It focuses on methods that monitor the component directly throughout the build process. This article is organized by the type of AM process and by the physics of the monitoring method. The discussion covers two types of monitoring possible with the PBF process: monitoring the area of the powder bed and component and monitoring the melt pool created by the laser or e-beam. Methods for layer monitoring include optical and thermal methods that monitor light reflected or emitted in the visible and infrared wavelengths, respectively. Monitoring methods for laser directed-energy deposition (DED) discussed are those that measure the size and shape of the melt pool, the temperature of the melt pool, and the plasma generated by the laser as it interacts with the molten metal.

This article is a brief account of low-energy ion-scattering spectroscopy (LEIS) for determining the atomic structure of solid surfaces. It begins with a description of the general principles of LEIS. This is followed by a section providing information on the equipment used for LEIS. Various steps involved in the sample preparation, calibration, and data analysis are then discussed. The article concludes with a section on the applications and interpretation of LEIS in material analysis, including discussion on surface structural analysis, layer-by-layer (Frank-van der Merwe) growth, and low-energy atom-scattering spectroscopy.

Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article provides a brief account of LEED, covering the principles and measurements of diffraction from surfaces. Some of the processes involved in sample preparation are described. In addition, the article discusses the limitations of surface-sensitive electron diffraction and the applications of LEED with examples.

Grain boundaries are interfaces between crystallites of the same phase but different crystallographic orientation. They can be characterized as being low angle or high angle. This article discusses the measurements of grain-boundary energy with a brief summary of different schemes for measuring grain-boundary surface tension. The atomistic simulations of grain-boundary energy, measurement of grain-boundary migration and the techniques used to monitor grain-boundary migration are reviewed. Several considerations and effects influencing the computation of grain-boundary mobility are also discussed.

Nuclear energy harnesses the power of atomic interactions, whether through the fission of large nuclei or the fusion of light elements. Additive manufacturing (AM) can play several roles in this sector and is actively being researched and applied, although challenges remain. This article provides a discussion of the opportunities, challenges, and example use cases of AM in the nuclear and wind energy sectors.

This article focuses on the directed-energy deposition (DED) additive manufacturing (AM) technique of biomedical alloys. First, it provides an overview of the DED process. This is followed by a section describing the design and development of the multiphysics computational modeling of the layer-by-layer fusion-based DED process. A brief overview of the primary governing equations, boundary conditions, and numerical methods prescribed for modeling laser-based metal AM is then presented. Next, the article discusses fundamental concepts related to laser surface melting and laser-assisted bioceramic coatings/composites on implant surfaces, with particular examples related to biomedical magnesium and titanium alloys. It then provides a review of the processes involved in DED of biomedical stainless steels, Co-Cr-Mo alloys, and biomedical titanium alloys. Further, the article covers novel applications of DED for titanium-base biomedical implants. It concludes with a section on the forecast of DED in biomedical applications.

Additive manufacturing (AM) has been growing as a significant research interest in academic and industry research communities. This article presents flexible and biocompatible energy-harvesting devices using AM technology. First, it discusses material selection for achieving piezoelectricity and triboelectricity. Then, the article highlights the structures of energy harvesters and describes their working mechanisms. Next, it covers the additively manufactured implantable piezoelectric and triboelectric energy harvesters. Further, the article describes the 3D-printed wearable energy harvesters as well as their applications. An overview of additively manufactured self-powered sensors is highlighted. Finally, the article discusses the issues for 3D-printed energy harvesters and their roadmap.