Search Results for target efficiency

This article begins with a description of the advantages and disadvantages of thermal spraying. It provides a discussion on the importance of substrate processing prior to coating and the role of undercutting in repair. The article reviews the steps for substrate preparation, namely, cleaning, roughening, masking, and preheating. Information on the equipment and process variables of dry abrasive grit blasting are also provided. The article describes the roles of spray stream and the spray pattern for all thermal spray processes. It discusses the defects arising from poor temperature control and from the variables influencing the manipulation of the spray torch. The article concludes with helpful information on calculating the process efficiency of thermal spraying.

Laser soldering uses a well-focused, highly controlled beam to deliver energy to a desired location for a precisely measured length of time. This article focuses on two types of laser soldering operations, namely, blind laser soldering and intelligent laser soldering. It discusses the function of the blind laser soldering and provides a brief description on key attributes of the blind laser soldering, including repeatability, speed, quality, safety, and flexibility. The article explores the function of the intelligent laser soldering and concludes with a section on key attributes of the intelligent laser soldering. The key attributes of the intelligent laser soldering include repeatability, speed, quality, safety, cost, and flexibility.

This article addresses problems, such as “in spec” dilemma and on-target key, associated with traditional approaches to quality. It discusses major robust design techniques, tools, and concepts, such as quality loss function, parameter design, tolerance design, signal-to-noise ratio, technology development, and orthogonal arrays.

Digital radiography is a technique that uses digital detector arrays (linear or area) to capture an X-ray photonic signal and convert it to an electronic signal for display on a computer. This article begins with an overview of real-time radiography and provides a schematic illustration of a typical radioscopic system using an X-ray image intensifier. It discusses the advantages and limitations of real-time radiography. Computed radiography (CR) is one of the radiography techniques that utilizes a reusable detector comprised of photostimuable luminescence (PSL) storage phosphor. The article provides a schematic illustration of a typical storage phosphor imaging plate. It concludes with a discussion on the benefits of digital radiography.

This article provides an introduction to x-ray spectrometry, and discusses the role of electromagnetic radiation, x-ray emission, and x-ray absorption. It focuses on the instrumentation of wavelength-dispersive x-ray spectrometers, and energy dispersive x-ray spectrometers (EDS) that comprise x-ray tubes, the analyzing system, and detectors. The fundamentals of EDS operation are described. The article also provides useful information on preparation of various samples, explaining the qualitative and quantitative analyses of EDS. It reviews the applications of the x-ray spectrometry.

This article presents a general description of pulsed-laser deposition. It describes the components of pulsed-laser deposition equipment. The article also discusses the effects of angular distribution of materials. Finally, the article reviews the characteristics of high-temperature superconductors and ferroelectric materials.

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.

Vapor-deposition processes fall into two major categories, namely, physical vapor deposition (PVD) and chemical vapor deposition (CVD). This article describes major deposition processes such as sputtering, evaporation, ion plating, and CVD. The list of materials that can be vapor deposited is extensive and covers almost any coating requirement. The article provides a table of some corrosion-resistant vapor deposited materials. It concludes with an overview of the applications of CVD and PVD coatings and a discussion on coatings for graphite, the aluminum coating of steel, and alloy coatings for aircraft turbines, marine turbines, and industrial turbines.

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.

Temperature control in heat treating is of paramount importance in maintaining the quality and achieving the desired metallurgical results. This article provides a detailed account of the factors affecting temperature control in heat treating furnaces, with information on temperature control systems, including contact sensors, noncontact sensors, controllers, energy-flow regulators, measurement instruments, and set-point programmers. Common contact sensors include temperature scales, thermocouples, and resistance temperature detectors, whereas optical pyrometers and on-line radiation thermometers fall under the noncontact type. The article describes two types of instrumentation used in heat treating: field test instruments for temperature-uniformity surveys and system-accuracy tests; and controlling, monitoring, and recording instruments for digital instrumentation.

This article provides a detailed account of X-ray spectroscopy used for elemental identification and determination. It begins with an overview of the operating principles of X-ray fluorescence (XRF) spectrometer, as well as a comparison of the operating principles of wavelength-dispersive spectrometer (WDS) and energy-dispersive spectrometer (EDS). This is followed by a discussion on the mechanism and effects of X-ray radiation, X-ray emission, and X-ray absorption. The article then discusses components used, operation, and applications of WDS and EDS. Some of the factors and processes involved in sample preparation for XRF analysis are also included. The article further provides information on the practical procedure for and the applications of WDS and EDS qualitative and quantitative analyses.

The application of three-dimensional printers can be revolutionary as a tool for the customization and personalization of pharmaceutical dosage forms. The areas of 3D printing applicable to pharmaceutical manufacturing can be segregated into three categories: extrusion technologies, powder-bed fusion, and stereolithography. Common extrusion-based technologies are fused deposition modeling and pressure-assisted microsyringe; powder-bed fusion is separated by binder jet and selective laser sintering. The synergies between pharmaceutical, or active pharmaceutical ingredient (API), and polymer printing are discussed in this article, with particular attention to how the incorporation of small-molecule APIs changes the material selection, design considerations, processing parameters, and challenges associated with each technology.

Integrated computational materials engineering refers to the use of computer simulations that integrate mathematical models of complex metallurgical processes with computer models used in component and process design. This article outlines an example of a computer-aided engineering tool, such as virtual aluminum castings (VAC), developed and implemented for quickly developing durable cast aluminum power train components. It describes the procedures for the model development of the VAC system. These procedures include linking the manufacturing process to microstructure, linking microstructures to mechanical properties, linking material properties to performance prediction, and model validation and integration into the engineering process. The article discusses the benefits of the VAC system in process selection, process optimization, and improving the component design criteria.

Additive manufacturing (AM), also referred to as three-dimensional printing or rapid prototyping, is a set of technologies that has rapidly evolved and has drawn much research attention in the manufacturing of high value-added products. This article focuses on dentistry, one of the fields in which AM has gained much traction. It discusses the AM processes used to produce dentures, crowns, and bridges. Digitization techniques, which are the first step and provide the CAD model for AM processes, are presented. Scanning technologies that are widely used in dental manufacturing are presented in detail, and the strengths and weaknesses of each process within their applications are discussed. AM processes are discussed in detail, and the materials that are widely used in AM-embedded dental manufacturing are briefly surveyed. The final section concludes with remarks and a preview of future research and practice directions.

Physics-based feedforward control is discussed in this article for two important laser-based metal additive manufacturing (AM) processes: directed-energy deposition and laser powder-bed fusion. For each type of process, control-oriented, lumped-parameter models that characterize melt pool dynamics as a function of process parameters are discussed first. Then, the derivation of model-based controllers is illustrated, followed by experimental evaluations of the model-based controller implemented as a feedforward control on a commercial AM system.

Radiography is the process or technique of producing images of a solid material on a paper/photographic film or on a fluorescent screen by means of radiation particles or electromagnetic waves of short wavelength. This article reviews the general characteristics and safety principles associated with radiography. There are two main aspects of safety: monitoring radiation dosage and protecting personnel. The article summarizes the major factors involved in both and discusses the operating characteristics of X-ray tubes. It describes the various methods of controlling scattered radiation: use of lead screens; protection against backscatter and scatter from external objects; and use of masks, diaphragms, collimators, and filtration. The article concludes with a discussion on image conversion media, including recording media, lead screens, lead oxide screens, and fluorescent intensifying screens.

The process of optimization involves choosing the best solution from a pool of potential candidate solutions. This article provides a description of some classes of problems and the optimization methods that solve them. These problems include the deterministic single-objective problem, the deterministic multiobjective problem, and the nondeterministic, stochastic optimization problem. The article presents several complementary approaches to solve a wide variety of single-objective and multiobjective mechanical engineering applications. Multiobjective optimization study and stochastic optimization studies are also discussed.

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.