This chapter discusses the sintering process for stainless steel powders and its influence on corrosion resistance. It begins with a review of sintering furnaces and atmospheres and the effect of temperature and density on compact properties such as conductivity, ductility, and strength. It then describes the relationship between sintered density and corrosion resistance and how it varies for different types of powders and operating environments. The chapter also explains how stainless steel powders respond to different sintering atmospheres, including hydrogen, hydrogen-nitrogen, and vacuum, and liquid-phase sintering processes.

After shaping and first-stage binder removal, the component (with remaining backbone binder) is heated to the sintering temperature. Further heating induces densification, evident as dimensional shrinkage, pore rounding, and improved strength. This chapter begins with a discussion on the events that are contributing to sintering densification, followed by a discussion on the driving forces, such as surface energy, and high-temperature atomic motion as well as the factors affecting these processes. The process of microstructure evolution in sintering is then described, followed by a discussion on the tools used for measuring bulk properties to monitor sintering and density. The effects of key parameters, such as particle size, oxygen content, sintering atmosphere, and peak temperature, on the sintered properties are discussed. Further, the chapter covers sintering cycles and sintering practices adopted as well as provides information on dimensional control and related concerns of sintering. Cost issues associated with sintering are finally covered.

This chapter recounts some of the early efforts and milestones in the development of stainless steel powders and their use in powder metallurgy applications.

This chapter provides an introduction to powder processing of binders and polymers. It sets the context for the remainder of the book by providing an overview of the topics discussed in the subsequent chapters and by providing introduction to powder-binder fabrication and customization of feedstock and describing the challenges in component production. The chapter also summarizes alphabetically a few key concepts in powder-binder processing.

This chapter includes a comprehensive set of definitions used in powder-binder processing.

This appendix is a compilation of terms and definitions associated with the processing, microstructure, and properties of powder metal stainless steels.

This chapter covers the basic steps of the powder metallurgy process, including powder manufacture, powder blending, compacting, and sintering. It identifies important powder characteristics such as particle size, size distribution, particle shape, and purity. It compares and contrasts mechanical, chemical, electrochemical, and atomizing processes used in powder production, discusses powder treatments, and describes consolidation techniques along with secondary operations used to obtain special properties or improve dimensional precision. It also discusses common defects such as ejection cracks, density variations, and microlaminations.

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 discusses the use of phase diagrams in alloy design, processing, and performance assessment. The examples cover both ferrous and nonferrous metals and a variety of goals and objectives. The chapter also identifies limitations and pitfalls associated with the use of phase diagrams.

Stainless steel powders are usually made by water or gas atomization. This chapter describes both processes and the properties and characteristics of the powders they produce. It also discusses secondary processes, including drying, screening, annealing, and lubricating, and the effects of iron contamination on corrosion resistance.

This chapter provides details on powder-binder processing for three materials, namely precipitation-hardened 17-4 PH stainless steel, cemented carbides, and alumina. The types of powders, binders, feedstock, shaping processes, debinding, sintering cycles, compositions, microstructure, distortion, postsintering treatments, and mechanical properties are presented for each. The shaping options include powder-binder approaches such as binder jetting, injection molding, extrusion, slip and slurry casting, centrifugal casting, tape casting, and additive manufacturing. Sintering options are outlined with respect to attaining high final properties.