This article provides a discussion on the following photographic equipment: point-and-shoot cameras, digital single-reflex cameras, stand-mounted digital zoom cameras, and digital microscope cameras. It presents two principal types of optical microscopes that are appropriate for visual examination of fractured parts: the stereomicroscope and the single-light-path digital microscope. The common features present on fracture surfaces are each considered separately, both in their significance and as photographic challenges. The article also presents a short note on low-magnification scanning electron microscopy and postcapture image processing.

This article presents a basic overview of technology-driven advances in the imaging of primarily metallic fracture surfaces. It describes various types of microscopes, including scanning electron, dual-beam, ion source, and transmission electron microscopes, and their capabilities. It also covers other useful hardware, such as computer-aided tomography (CAT) and micro-computer-aided tomography (micro-CAT) instruments. The article introduces some of the fracture image postprocessing methods and software, including image registration or alignment, focus stacking, Z-stacking, focal plane merging, and image stitching.

The development of quantitative fractography (QF) parameters basically requires topological data of a fracture surface that can be derived from the stereological analysis of multiple projected scanning electron microscope (SEM) images; the profilometry-based techniques that measure the fracture surface profile along x-y sections of a fracture surface from metallographic sections or nondestructive techniques; and the three-dimensional reconstruction of the fracture surface topology using imaging methods such as stereo SEM imaging and confocal scanning laser microscopy. These three general methods of assessing fracture surface topology are reviewed in this article.

This article provides an overview of polymer fractography, with examples of various fracture surfaces created under diverse loading conditions. The focus is on the interpretation of polymer fracture-surface features in light of the unique viscoelastic nature of polymers. The article presents fractographic examples of three time-dependent cracking mechanisms: fatigue fracture, creep rupture, and environmental stress cracking. It details characteristic fractographic features that can be observed in optical microscopy (OM) and scanning electron microscopy (SEM).

In situ process monitoring includes any technologies that monitor or inspect during an additive manufacturing (AM) process. This article presents the types, process considerations, and challenges of in situ monitoring technologies that can be implemented during an AM process. The types include system health monitoring, melt pool monitoring, and layer monitoring. The article discusses data analysis, and provides an overview of the integration of sensors into AM machines.

Piezoelectric jetting is a common form of additive manufacturing technology. With the development of material science and manufacturing devices, piezoelectric jetting of biomaterials has been applied to various fields including biosensors, tissue engineering, deoxyribonucleic acid (DNA) synthesis, and biorobots. This article discusses the processes involved in piezoelectric jetting of biosensors and biorobots and the applications of piezoelectric jetting for tissue engineering and producing DNA. In addition, it reviews the challenges and perspectives of piezoelectric jetting.

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.

X-ray spectroscopy is generally accepted as the most useful ancillary technique that can be added to any scanning electron microscope (SEM), even to the point of being considered a necessity by most operators. While “stand-alone” x-ray detection systems are used less frequently in failure analysis than the more exact instrumentation employed in SEMs, the technology is advancing and is worthy of note due to its capability for nondestructive analysis and application in the field. This article begins with information on the basis of the x-ray signal. This is followed by information on the operating principles and applications of detectors for x-ray spectroscopy, namely energy-dispersive spectrometers, wavelength-dispersive spectrometers, and handheld x-ray fluorescence systems. The processes involved in x-ray analysis in the SEM and handheld x-ray fluorescence analysis are then covered. The article ends with a discussion on the applications of x-ray spectroscopy in failure analysis.

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.

This article endeavors to familiarize the reader with a selection of different ionization designs and instrument components to provide knowledge for sorting the various analytical strategies in the field of solid analysis by mass spectrometry (MS). It begins with a description of the general principles of MS. This is followed by sections providing a basic understanding of instrumentation and discussing the operating requirements as well as practical considerations related to solid sample analysis by MS. Instrumentation discussed include the triple quadrupole mass spectrometer and the time-of-flight mass spectrometer. Inductively coupled plasma and thermal ionization MS provide atomic information, and direct analysis in real-time and matrix-assisted laser-desorption ionization MS are used to analyze molecular compositions. The article describes various factors pertinent to ionization methods, namely glow discharge mass spectrometry and secondary ion mass spectrometry. It concludes with a section on various examples of applications and interpretation of MS for various materials.

This article describes various methods of electrochemical analysis, namely coulometry, electrogravimetry, voltammetry, electrometric titration, and nanometer electrochemistry. The discussion covers the general uses, sample requirements, application examples, advantages, and limitations of these methods. Some of the factors pertinent to electrochemical cells are also provided. In addition, the article provides information on various potentiometric membrane electrodes used to quantify numerous ionic and nonionic species.

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.

This article provides a detailed account of the concepts of single-crystal x-ray diffraction (XRD). It begins with a historical review of XRD methods, followed by a description of the various factors involved in crystal symmetry. The article then focuses on the phase problem in x-ray structural analysis and validation of the structural model. Some of the factors to be considered for performing experimental procedure are provided. The article presents several examples of applications of single-crystal XRD. The following sections cover the crystallographic problem in terms of structural analysis, software programs for crystal structure solution and refinement, and visualization of crystal structures. The article ends with a discussion on various databases available for single-crystal XRD analysis.

The reflected light microscope is the most commonly used tool to study the microstructure of metals, composites, ceramics, minerals, and polymers. For the study of the microstructure of metals and alloys, light microscopy is employed in the reflected-light mode using either bright-field illumination, dark-field illumination, polarized light illumination, or differential interference contract, generally by the Nomarski technique. This article concentrates on how to reveal microstructure properly to enable the proper identification of the phases and constituents and, if needed, measuring the amount, size, and spacing of constituents, using the light optical microscope. The discussion covers the examination of microstructures using different illumination methods and includes a comparison between light optical images and scanning electron microscopy images of microstructure.

The electron backscatter diffraction (EBSD) technique has proven to be very useful in the measurement of crystallographic textures, orientation relationships between phases, and both plastic and elastic strains. This article focuses on backscatter diffraction in a scanning electron microscope and describes transmission Kikuchi diffraction. It begins with a discussion on the origins of EBSD and the collection of EBSD patterns. This is followed by sections providing information on EBSD spatial resolution and system operation of EBSD. Various factors pertinent to perform an EBSD experiment are then covered. The article further describes the processes involved in sample preparation that are critical to the success or usefulness of an EBSD experiment. It also discusses the applications of EBSD to bulk samples and the development of EBSD indexing methods.

Machine vision, also referred to as computer vision or intelligent vision, is a means of simulating the image recognition and analysis capabilities of the human eye and brain system with digital techniques. The machine vision functionality is extremely useful in inspection, supervision, and quality control applications. This article presents a variety of machine vision functions for different purposes and provides a comparison of machine and human vision capabilities in a table. It discusses the processes of a machine vision system: image acquisition, image preprocessing, image analysis, and image interpretation. The article provides information on the uses of machine vision systems in three categories of manufacturing applications: visual inspection, identification of parts, and guidance and control applications.

Ultrasonic inspection is a family of nondestructive methods in which beams of high-frequency mechanical waves are introduced into materials, using transducers, for the detection and characterization of both surface and subsurface anomalies and flaws in the material. This article describes the basic equipment in ultrasonic inspection systems, and lists the advantages and disadvantages of these systems. It discusses the applications of ultrasonic inspection and also the general characteristics of ultrasonic waves in terms of wave propagation, longitudinal waves, transverse waves, surface waves, and lamb waves. The article reviews the major variables in ultrasonic inspection, including frequency, acoustic impedance, angle of incidence, and beam intensity. It discusses the attenuation of ultrasonic beams and provides information on the pulse-echo and transmission methods for implementing ultrasonic inspection.

This article describes the basic features of electromagnetic acoustic transducers (EMATs) and discusses their existing and some potential uses within the field of ultrasonic nondestructive evaluation (UNDE). It provides sufficient basic and practical information to make an informed choice when considering the transducer to be used for any particular UNDE application. The article describes how different types of EMATs operate and presents their fundamental and some practical limitations. It summarizes the representative literature for electromagnetic acoustic transducer UNDE applications. Some successful uses of EMATs are mentioned to illustrate the depth, range, and potential of commercial EMAT applications. The article concludes with information on the commercial sources for EMAT systems and components.

Visual inspection (VI) is the oldest inspection technique man has used as a quality-control tool to evaluate products, assess their final form in terms of fabrication accuracy and external features based on experience, and decide on their acceptance or rejection. This article discusses the basic principles of visual inspection in terms of direct visual examination and indirect visual examination as well as advantages and limitations of visual inspection. It reviews the factors affecting the effectiveness of VI as a nondestructive testing (NDT): lighting conditions of observation, condition of surface under inspection, physical state/condition of inspector, proper training of personnel and level of expertise, and knowledge of applicable standards. The article provides schematic illustrations of rigid borescopes, fiberscopes, and videoscopes. It concludes with a discussion on automated optical inspection systems.

Liquid penetrant inspection is a nondestructive method of revealing discontinuities that are open to the surfaces of solid and essentially nonporous materials. This article provides information on physical principles, evolution, description, and processing parameters of liquid penetrant inspection as well as materials used. It discusses some of the more generally used types of equipment used in penetrant inspection and their requirements. The article describes various penetrant methods and their selection criteria and provides information on precleaning and postcleaning of workpieces before and after penetrant inspection. The quality assurance and maintenance of penetrant inspection materials are also discussed. The article concludes with information on specifications and standards applicable to penetrant inspection.