Search Results for vacuum atomization

Atomization is the dominant method for producing metal and prealloyed powders from aluminum, brass, iron, low-alloy steels, stainless steels, tool steels, superalloys, titanium alloys, and other alloys. The general types of atomization processes encompass a number of industrial and research methods. This article describes the key process variables and production factors for the industrial methods: two-fluid, centrifugal, vacuum or soluble-gas, and ultrasonic atomization. It also reviews the effect of atomization methods and process variables on key powder characteristics such as the average particle size, particle size distribution or screen analysis, particle shape, chemical composition, and microstructure.

This article describes procedures for producing powder metallurgy high-speed tool steel powder by inert-gas atomization, followed by compaction by hot isostatic pressing. These include the anti-segregation process (ASP) and the crucible particle metallurgy (CPM) process. The article reviews the properties of ASP and CPM and summarizes the procedures to heat treat ASP high-speed tool steels. It discusses the processing steps, advantages, and applications of the FULDENS process that uses water-atomized powders compacted by vacuum sintering. The article also provides information on the applications of tool steels.

Ion-beam-assisted deposition (IBAD) refers to the process wherein evaporated atoms produced by physical vapor deposition are simultaneously struck by an independently generated flux of ions. This article discusses the energy utilization of this process. It describes the physical and chemical processes occurring at the film-vacuum interface during IBAD and dual-ion-beam sputtering with illustrations. The article also reviews the methods used for large-area, high-volume implementation of IBAD and the modes of film formation for IBAD. It contains a table that presents information on deposition and synthesis of inorganic compounds by IBAD and concludes with a discussion on the improved coating properties, advantages, limitations, and applications of IBAD.

In secondary ion mass spectroscopy (SIMS), an energetic beam of focused ions is directed at the sample surface in a high or ultrahigh vacuum (UHV) environment. The transfer of momentum from the impinging primary ions to the sample surface causes sputtering of surface atoms and molecules. This article focuses on the principles and applications of high sputter rate dynamic SIMS for depth profiling and bulk impurity analysis. It provides information on broad-beam instruments, ion microprobes, and ion microscopes, detailing their system components with illustrations. The article graphically illustrates the SIMS spectra and depth profiles of various materials. The quantitative analysis of ion-implantation profiles, instrumental features required for secondary ion imaging, the analysis of nonmetallic samples, detection sensitivity, and the applications of SIMS are also discussed.

This article discusses the adhesion behavior of materials in low-pressure and vacuum environments and provides a schematic illustration of an apparatus for measuring adhesion and friction in ultrahigh vacuum. It describes the effects of low-oxygen pressures and vacuum environments on adhesion and friction, as well as the effects of defined exposure to oxygen on friction. The article discusses the wear of various metals in contact with ceramics, and alloying element effects on friction, wear, and transfer of materials. It also describes studies that characterize the contributions of surface contamination and chemical changes to tribology in low-pressure and vacuum environments.

This article discusses the fundamentals of thermal vaporization and condensation and provides information on the various vaporization sources and methods of vacuum deposition. It offers an overview of reactive evaporation and its deposition techniques. The article also explains the advantages, limitations, and applications of vacuum deposition processes. Finally, it provides information on the gas evaporation process, its processing chamber, and related systems.

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.

Physical vapor deposition (PVD) coatings are harder than any metal and are used in applications that cannot tolerate even microscopic wear losses. This article describes the three most common PVD processes: thermal evaporation, sputtering, and ion plating. It also discusses ion implantation in the context of research and development applications.

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.

This article focuses on various vacuum heat treating processes for additively manufactured parts, namely annealing and stress relieving, solid-solution annealing, and solution treating and aging. It addresses several practical concerns involved in using vacuum heat treatment, including temperature measurement, unvented cavities, loose powder, and direct contact of metals in the high-temperature vacuum. The article provides a short discussion on sintering and evaporation of metals in vacuum furnaces.

This article focuses on the modes of operation, physical basis, sample requirements, properties characterized, advantages, and limitations of the characterization methods used to evaluate the physical morphology and chemical properties of component surfaces for medical devices. These methods include light microscopy, scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy.

The scanning electron microscope (SEM) is one of the most versatile instruments for investigating the microscopic features of most solid materials. The SEM provides the user with an unparalleled ability to observe and quantify the surface of a sample. This article discusses the development of SEM technology and operating principles of basic systems of SEM. The basic systems covered include the electron optical column, signal detection and display equipment, and the vacuum system. The processes involved in the preparation of samples for observation using an SEM are described, and the application of SEM in fractography is discussed. The article covers the failure mechanisms of ductile failure, brittle failure, mixed-mode failure, and fatigue failure. Lastly, image dependence on microscope type and operating parameters is also discussed.

The electronic microcircuit industry has placed severe demands on metal suppliers to provide metals of the highest reproducible purity attainable as a result of the constant quest for the true values of physical and chemical properties of metals. This article describes the commonly used methods for ultrapurification of metals produced by electrolytic processes, including fractional crystallization, zone refining, vacuum melting, distillation, chemical vapor deposition, and solid state refining techniques. In addition, it describes the trace element analysis and resistance-ratio test methods used to characterize purity. Tables list the values for resistance ratios of zone-refined metals and their corresponding chemical compositions, and provide an example of the detection of impurities to concentrations in the parts per billion range, utilizing a combination of the glow discharge mass spectroscopy method and Leco combustion methods.

The scanning electron microscopy (SEM) is one of the most versatile instruments for investigating the microstructure of metallic materials. This article highlights the development of SEM technology and describes the operation of basic systems in an SEM, including the electron optical column, signal detection and display equipment, and vacuum system. It discusses the preparation of samples for observation using an SEM and describes the application of SEM in fractography. If the surface remains unaffected and undamaged by events subsequent to the actual failure, it is often a simple matter to determine the failure mode by the use of an SEM. In cases where the surface is altered after the initial failure, the case may not be so straightforward. The article presents typical examples that illustrate these points. Image dependence on the microscope type and operating parameters is also discussed.