Search Results for turner

This article first describes the two methods used in the 1998 U.S. corrosion cost study. In the first method, the cost was determined by summing the costs for corrosion control methods and contract services. In the second, the cost of corrosion was first determined for specific industry sectors and then extrapolated to calculate a national total corrosion cost. The article then reports the results and conclusions of the study. It concludes with information on corrosion prevention strategies.

As additive manufacturing (AM) gains maturity as a manufacturing technique for production in many industrial sectors, inspection as a tool for quality control gains importance. This article is focused on the field of dimensional metrology, which is typically concerned with the verification of size, location, form, and surface topography of geometric features. This is split into two categories: geometric (size, location, form) and surface measurement (topography). The article also focuses on applicable inspection technologies, and it discusses the context within digital thread manufacturing. A case study on the Digital Inspection Requirements Enhancing Coverage and Traceability (DIRECT) is also presented.

This article provides a clear but nonexhaustive description of the general principle of atomic emission, with a particular focus on instrumentation, and summarizes the main characteristics of the inductively coupled plasma optical emission spectrometer technique. Basic atomic theory as well as the instrument characteristics and their influence on the instrument performances are presented. The advantages, drawbacks, and developments of this technique are discussed, and, finally, alternative techniques and examples of applications are provided.

Compacted graphite iron (CGI) invariably includes some nodular (spheroidal) graphite particles, giving rise to the definition of the microstructure in terms of percent nodularity. This article discusses the graphite morphology and mechanical and physical properties of CGI. The mechanical and physical properties of CGI with ferritic and pearlitic matrix structures are summarized in a table. The article describes the standards for CGI, with the definition of the grades based on the minimum tensile strength. It also provides information on the applications of compacted graphite iron castings.

Honeycomb-cored sandwich panels increase part stiffness at a lower weight than monolithic composite materials. This article illustrates an area of a honeycomb-cored sandwich structure composite cross section that is viewed using transmitted polarized light. This area shows the differences in the constituents and resin intermingling. The article discusses the factors that govern the honeycomb core movement and honeycomb core crush, with illustrations. Some common tests performed on honeycomb composites to characterize the skin-to-core bond strength are the climbing drum peel and flatwise tensile tests. The article concludes with a description on the reasons for core failure, which are analyzed after these tests.

This article describes different methods by which the composition of cast iron can be analyzed. It provides particular emphasis on the methods for evaluating the graphitization potential of a melt with prescribed limits on carbon, silicon, and alloying elements. The article discusses the effect of cooling rate on the graphitization of a given composition by chill and wedge tests. Thermal analysis of cooling curves gives excellent information about the solidification and subsequent cooling of cast iron alloys. The article presents some applications of the cooling curve analysis and explains the evaluation of carbon-silicon contents, graphite shape, graphite nucleation, and contraction-expansion balance. It illustrates the use of an immersion steel sampling device for compacted graphite iron production and provides information on the ferrite-pearlite ratio in ductile iron.

This article introduces the principles of Raman spectroscopy and the representative materials characterization applications to which Raman spectroscopy has been applied. It includes a discussion of light-scattering fundamentals and a description of the experimental aspects of the technique. Emphasis has been placed on the different instrument approaches that have been developed for performing Raman analyses on various materials. The applications presented in the article reflect the breadth of materials characterization uses for Raman spectroscopy and highlight the analysis of bulk material and of surface and near-surface species.

This article introduces the principles of Raman spectroscopy and the representative materials characterization applications to which Raman spectroscopy has been applied. A discussion on light-scattering fundamentals and a description of the experimental aspects of the technique are included. Emphasis is placed on the different instrument approaches that have been developed for performing Raman analyses on various materials. The applications presented reflect the breadth of materials characterization uses for Raman spectroscopy and highlight the analysis of bulk material and of surface and near-surface species.

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is an analytical technique for elemental determinations in the concentration range of major to trace based on the principles of atomic spectroscopy. This article provides a description of the basic atomic theory, and explains the analytical procedures and various interference effects of ICP, namely, spectral, vaporization-atomization, and ionization. It provides a detailed discussion on the principal components of an analytical ICP system, namely, the sample introduction system; ICP torch and argon gas supplies; radio-frequency generator and associated electronics; spectrometers, such as polychromators and monochromators; detection electronics and interface; and the system computer with appropriate hardware and software. The article also describes the uses of direct-current plasma, and provides examples of the applications of ICP-AES.

Mechanical properties are often the most important properties in the design and selection of engineering plastics. Temperature, molecular structure, crystallinity, viscoelasticity, and effects of environment, fillers and reinforcements are considered as the basic factors affecting the mechanical properties of engineering plastics. The testing methods for determining mechanical properties, including stress-strain test, modulus-directed tensile test, strength test, strength-directed tensile test, impact test, and dynamic mechanical test are discussed.

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 describes the classification of fuel cells depending on the operating temperature and type of electrolytes used. This classification includes alkaline fuel cells, phosphoric acid fuel cells, polymer electrolyte membrane fuel cells (PEMFCs), molten carbonate fuel cells (MCFCs), and solid oxide fuel cells (SOFCs). The article explains the corrosion processes in fuel cells due to solid-gas interactions, solid-liquid interactions, and solid-solid interactions. It discusses the long-term performance stability and long-term degradation processes of PEMFCs, MCFCs, and SOFCs. The article reviews the development of chemically and structurally compatible component materials in PEMFCs, MCFCs, and SOFCs.

The electrode potential is one of the most important parameters in the thermodynamics and kinetics of corrosion. This article discusses the fundamentals of electrode potentials and illustrates the thermodynamics of chemical equilibria by using the hydrogen potential scale and the Nernst equation. It describes galvanic cell reactions and corrosion reactions in an aqueous solution in an electrochemical cell. The article explores the most common cathodic reactions encountered in metallic corrosion in aqueous systems. The reactions included are proton reduction, water reduction, reduction of dissolved oxygen, metal ion reduction, and metal deposition. The article also presents the standard equilibrium potentials measured at 25 deg C relative to a standard hydrogen electrode for various metal-ion electrodes in a tabular form.

This article describes the determination of wear loss by measuring either mass change or dimensional change of lubricants and materials. It discusses the principles, advantages and disadvantages of mass loss measures and dimensional measures of wear. The article details wear measurement at the nanoscale, such as atomic force microscopy (AFM) measurement and scanning electron microscopy measurement. It reviews the techniques of wear measurement at the atomic level, namely, transmission electron microscopy (TEM) measurement and AFM combined with TEM measurement.

Weldments exhibit special microstructural features that need to be recognized and understood in order to predict acceptable corrosion service life of welded structures. This article describes some of the general characteristics associated with the corrosion of weldments. It emphasizes the role of macrocompositional and microcompositional variations to bring out differences that need to be realized in comparing corrosion of weldments to that of wrought materials. The article concludes with a discussion on important welding practices used to minimize corrosion in weldments.

Additive manufacturing (AM) process modalities offer access to rich sets of structures for metallic materials that are otherwise difficult to obtain through a single conventional manufacturing process for bulk-scale materials. This article presents the primary aim of understanding the linkage between the process and structure in AM, which is typically focused on the correlation of machine process settings to defects such as material porosity and cracking. It also presents the development of scan strategies for site-specific microstructure control and discusses factors influencing process-structure relationships in fusion metals AM.

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.