This chapter provides an overview of sintering techniques and the microstructures and properties that can be achieved in different material systems. It covers conventional furnace sintering, microwave and laser sintering, hot and hot-isostatic pressing, and spark plasma sintering. It describes the advantages and disadvantages of each method, the mechanisms involved, and the effect of sintering parameters on the density, grain size, and mechanical properties of titanium and tungsten heavy alloys, stainless steel, cemented carbides, ceramics, composites, and rare earth magnets.

The porous structure of powder-metal materials, and thus the sintering method, has a significant impact not only on the properties of PM components, but also on how they respond to surface treatments and fabrication processes such as coating and joining. This chapter explains how the microstructure of PM parts achieved by different sintering methods influences the development of galvanized coatings and the mechanisms involved in sinter bonding and various welding and brazing processes. It presents and interprets the results of several studies in which PM materials, including iron, copper, stainless steel, brass, and bronze alloys, are joined by spot welding, projection welding, and solid-state welding as well as furnace and microwave brazing. It also examines the effects of ZrSiO 4 additions on the friction and wear behaviors of PM bronze brake-lining materials.

Thermal barrier coatings (TBCs) are applied using thermal spray coating (TSC) processes to components that are internally cooled and operated in a heated environment. The TSC microstructures are prone to interactions with common metallographic procedures that may result in artifacts and misinterpretation of the TSC microstructure. This article aims to aid in identifying metallographic TSC artifacts, specifically in the air plasma spray zirconia-based TBC, including both of its common constituents, the bond coating and the top coating. Artifacts that result from specific sectioning and mounting practices, as well as from different polishing times, are presented. Additionally, the article discusses the factors in optical microscopy and scanning electron microscopy that affect microstructure interpretation.

This chapter is intended to identify materials, processes, and designs that will lead to great advances in powder-binder forming technologies. It discusses some of the structures obtained through these advances in powder-binder technologies such as binder jetting and extrusion-based additive manufacturing, including bound-metal deposition and fused-filament fabrication: oxidation-resistant high-temperature alloys, anisotropic structures, submicrometer-scale structures, surface hard materials, and artist metallic clays. Some of the advances discussed include the developments in process involving plastics, emulsions, ceramics, and porous structures and foams. Improvements in the design processes have led to the development of functional structures, controlled porosity, and bioinspired structures.

Glasses and ceramics are susceptible to stress-corrosion cracking (SCC), as are metals, but the underlying mechanisms differ in many ways. One of the major differences stems from the lack of active dislocation motion that, in metals, serves to arrest cracks by reducing stress concentrations at flaw tips. As a result, even relatively small flaws (20 to 50 μm in radius) can cause glasses and ceramics to fail. This chapter examines the propensity of flaws to grow in glass and ceramic materials exposed to different environments, especially water, at stresses well below those that would produce immediate failure. It describes crack growth mechanisms, explains how to measure crack growth rates and predict time to failure, and provides crack growth data for a number of materials and environments.

This chapter discusses the composition, properties, and uses of crystalline ceramics, glasses, clay, and concrete mixes. It also discusses the carbon structure of diamond, graphite, fullerenes, and nanotubes.

This chapter covers the fatigue and fracture behaviors of ceramics and polymers. It discusses the benefits of transformation toughening, the use of ceramic-matrix composites, fracture mechanisms, and the relationship between fatigue and subcritical crack growth. In regard to polymers, it covers general characteristics, viscoelastic properties, and static strength. It also discusses fatigue life, impact strength, fracture toughness, and stress-rupture behaviors as well as environmental effects such as plasticization, solvation, swelling, stress cracking, degradation, and surface embrittlement.

Ceramics normally have high melting temperatures, excellent chemical stability and, due to the absence of conduction electrons, tend to be good electrical and thermal insulators. They are also inherently hard and brittle, and when loaded in tension, have almost no tolerance for flaws. This chapter describes the applications, properties, and behaviors of some of the more widely used structural ceramics, including alumina, aluminum titanate, silicon carbide, silicon nitride, zirconia, zirconia-toughened alumina (ZTA), magnesia-partially stabilized zirconia (Mg-PSZ), and yttria-tetragonal zirconia polycrystalline (Y-TZP). It also provides information on materials selection, design optimization, and joining methods, and covers every step of the ceramic production process.

This chapter reviews materials issues encountered in joining, including challenges involved in welding of dissimilar metal combinations; joining of plastics by mechanical fastening, solvent and adhesive bonding, and welding; joining of thermoset and thermoplastic composite materials by mechanical fastening, adhesive bonding, and, for thermoplastic composites, welding; the making of glass-to-metal seals; and joining of oxide and nonoxide ceramics to themselves and to metals by solid-state processes and by brazing. The classification, types, applications, and the mechanism of each of these methods are covered. The factors influencing joint integrity and the main considerations in welding dissimilar metal combinations are also discussed.

This chapter explains the distinction between materials and matter through the concept of microstructure. It presents the history of matter science and the establishment of metallography. The chapter provides an overview of the progress of steel technology, progress in synthetic polymers and ceramics, and establishment and development of materials science.

This chapter discusses the effect of fatigue on polymers, ceramics, composites, and bone. It begins with a general comparison of polymers and metals, noting important differences in microstructure and cyclic loading response. It then presents the results of several studies that shed light on the fatigue behavior and crack growth mechanisms of common structural polymers and moves on from there to discuss the fatigue behavior of bone and how it compares to stable and cyclically softening metals. It also discusses the fatigue characteristics of engineered and composited ceramics and ceramic fiber-reinforced metal-matrix composites.

Structural and fracture mechanics-based tools for metals are believed to be applicable to nonmetals, as long as they are homogeneous and isotropic. This chapter discusses the essential aspects of the fatigue and fracture behaviors of nonmetallic materials with an emphasis on how they compare with metals. It begins by describing the fracture characteristics of ceramics and glasses along with typical properties and subcritical crack growth mechanisms. It then discusses the properties of engineering plastics and the factors affecting crack formation and growth, fracture toughness, fatigue life, and stress rupture failures.

This chapter describes tensile testing of advanced ceramic materials, a category that includes both noncomposite, or monolithic, ceramics and ceramic-matrix composites (CMCs). The chapter presents four key considerations that must be considered when carrying out tensile tests on advanced monolithic ceramics and CMCs. These include effects of flaw type and location on tensile tests, separation of flaw populations, design strength and scale effects, and lifetime predictions and environmental effects. The chapter discusses the advantages, problems, and complications of four basic categories of tensile testing techniques as applied to ceramics and CMCs. These categories are true direct uniaxial tensile tests at ambient temperatures, indirect tensile tests, tests where failure is presumed to result from tensile stresses, and high-temperature tensile tests.

This chapter details low-temperature test procedures and equipment. It discusses the role temperature plays in the properties of typical engineering materials. The effect that lowering the temperature of a solid has on the mechanical properties of a material is summarized for three principal groups of engineering materials: metals, ceramics, and polymers (including fiber-reinforced polymers). The chapter describes the factors that influence the selection of tensile testing procedures for low-temperature evaluation, along with a comparison of tensile and compression tests. It covers the parameters and standards related to low-temperature tensile testing. The chapter discusses the factors involved in controlling test temperature. Finally, the chapter discusses the safety issues concerning the use of cooled methanol, liquid-nitrogen, and liquid helium.