Search Results for electrical properties

This chapter presents topics pertaining to resistance at cryogenic temperatures: measurement, the resistive mechanisms, and available data. The chapter also presents brief descriptions of the various mechanisms that are operative in producing resistance at low temperatures. The alloys discussed are the nondilute mixtures of metals. An introduction to low-temperature electrical properties of specific metals and alloys is included.

This article discusses electrical testing and recommended procedures for determining the electrical properties of insulating materials, with particular emphasis on plastics. It describes the electrical characteristics of various forms of plastics and also presents definitions of the terms used in connection with testing and specifying plastics for electrical applications.

The physical properties of a material are those properties that can be measured or characterized without the application of force and without changing material identity. This chapter discusses in detail the common physical properties of metals, namely density, electrical properties, thermal properties, magnetic properties, and optical properties. Some physical properties for a number of metals are given in a table.

This article discusses the compositions, properties, and uses of silver, gold, and platinum group metals, including platinum, rhodium, iridium, ruthenium, and osmium. It describes the role of various alloying elements and explains how they affect physical, mechanical, and electrical properties as well as corrosion resistance.

This appendix is a collection of tables containing thermal, electrical, mechanical, and physical property data for metals under various conditions. It also includes the periodic table of elements.

This article presents a general overview of outdoor weather aging factors, their effects on plastic materials, and the accelerated test methods that can be used to estimate the reaction of a plastic component during actual use. Weather and radiation factors that contribute to degradation in plastics include temperature variations, moisture, sunlight, oxidation, microbiologic attack, and other environmental elements. The article also describes the tests used to predict the behavior of a plastic material to outdoor exposure, discussing the use of xenon arc lamp for the weatherometer and fadeometer and the use of fluorescent sunlamp in test devices.

This chapter describes how forces and temperatures generated during sintering influence particle bonding, grain growth, shrinkage, and densification as well as bulk material properties. It explains how density, a good predictor of mechanical and electrical properties, can be controlled by proper selection of sintering time, temperature, and particle size for various steels, ceramics, and tungsten and titanium alloys.

This article explains how alloying elements affect the properties and behaviors of electrical contacts. It describes the composition, strength, hardness, and conductivity of a wide range of contact alloys and composites based on silver, copper, gold, platinum, palladium, tungsten, and molybdenum, and related oxides and carbides.

This chapter describes the molecular structures and chemical reactions associated with the production of thermoset and thermoplastic components. It compares and contrasts the mechanical properties of engineering plastics with those of metals, and explains how fillers and reinforcements affect impact and tensile strength, shrinkage, thermal expansion, and thermal conductivity. It examines the relationship between tensile modulus and temperature, provides thermal property data for selected plastics, and discusses the effect of chemical exposure, operating temperature, and residual stress. The chapter also includes a section on the uses of thermoplastic and thermosetting resins and provides information on fabrication processes and fastening and joining methods.

This chapter discusses the basic principles of induction heating and related engineering considerations. It describes the design and operation of induction coils, the magnitude and distribution of magnetic fields, and the forces that generate eddy currents in metals. It explains how induced electrical current causes metal to heat in proportion to their electrical resistance and how it affects temperature dependent properties such as resistivity and specific heat and, in turn, heating rates and efficiencies. It also discusses the effect of hysteresis and explains why eddy currents tend to be confined to the outer surface of the workpiece, a phenomenon known as the skin effect. The chapter includes several data plots showing how the depth of heating varies with frequency and how heating time, power density, and thermal conduction rate correspond with hardening depth.

This article discusses the general purpose of alloying and identifies some of the material properties and behaviors that can be improved by adding various elements to the base metal. It explains how alloying can make metals stronger and more resistant to corrosion and wear as well as easier to cast, weld, form, and machine. It also discusses some of the alloying techniques that have been developed to address problems stemming from dissimilarities between the base metal and alloying or inoculate material.

This chapter describes the properties and uses of aluminum, magnesium, titanium, and other nonferrous alloys. It also discusses the effect of cold working and the process of annealing, including recovery, recrystallization, and grain growth.

This article discusses the compositions, structures, and properties of the most common grades of soft magnetic metals and permanent magnet alloys. It explains how alloying additions and impurities affect the magnetic properties of these materials, which include commercially pure and phosphorus irons, low-carbon and silicon steels, ferritic stainless steels, and nickel-iron and iron-cobalt alloys.

This introductory article describes the various aspects of chemical structure and composition that are important to an understanding of polymer properties and their eventual effect on the end-use performance of engineering plastics, namely thermoplastics and thermosets. The most important properties of polymers and the most significant influences of structure on those properties are covered. The article also includes some general information on the classification and naming of polymers and plastics.

This article provides a brief description of commercially important thermal spray processes and gives examples of applications and application requirements. The processes covered are flame, wire arc, plasma, high-velocity oxyfuel processes, detonation gun, and cold spray methods. Examples are provided of the applications in aerospace, automotive, and medical device industries as well as the use of thermal spray as an additive manufacturing technique.

This chapter begins with a brief review of the different types of surface treatments and coatings used in industry and their effect on properties and performance. It then discusses the importance of corrosion and wear treatments and the consequences of failing to properly implement them in critical industries such as mining, energy production, transportation, and mineral and chemical processing. The chapter also describes basic approaches to dealing with corrosion and wear in steel.

This article describes in more detail the fundamental building-block level, atomic, then expands to a discussion of molecular considerations, intermolecular structures, and finally supermolecular issues. An explanation of important thermal, mechanical, and physical properties of engineering plastics and commodity plastics follows, and the final section briefly outlines the most common plastics manufacturing processes.

This chapter examines some of the behaviors that suit materials for electrical and electronic applications. It begins by explaining how charge carriers move in metals and semiconductors and how properties such as conductivity, mobility, and resistivity are derived. It discusses the significance of energy bands, intrinsic and extrinsic conduction, and the properties of compound semiconductors. It also covers semiconductor devices, including p-n junctions, light emitting diodes, transistors, and piezoelectric crystals.

This appendix contains tables listing the physical and mechanical properties of stainless steel engineering alloys. The physical properties covered are density, modulus of elasticity, coefficient of thermal expansion, thermal conductivity, specific heat, and electrical resistivity. The mechanical properties listed include yield strength, tensile strength, elongation and hardness.

This chapter describes the physical properties of steels used for castings. The properties covered include density, modulus of elasticity, Poisson's ratio, shear modulus, thermal expansion, thermal conductivity, specific heat, thermal diffusivity, electrical resistivity, and magnetic properties.