This article focuses on the production methods, properties, and applications of two main types of commercially available continuous-length ceramic fibers, namely, oxide fibers based on the alumina-silica system and on alpha-alumina, and nonoxide fibers based primarily on beta-phase silicon carbide. It provides a discussion on factors that are considered in understanding thermostructural capability of ceramic fiber for high-temperature ceramic-matrix composites (CMC) applications. The article tabulates other commercial oxide and nonoxide fiber types for CMC reinforcement.

For the reinforcement of metal-matrix composites, four general classes of materials are commercially available: oxide fibers based primarily on alumina and alumina silica systems, nonoxide systems based on silicon carbide, boron fibers, and carbon fibers. This article discusses the key aspects of aluminum oxide fibers, silicon carbide fibers, boron fibers, and carbon fibers. The commercial fibers for reinforcement of metal-matrix composites are presented in a table. A tabulation of the coating schemes for silicon carbide monofilament fibers is also provided.

This article discusses the mechanisms for enhancing the reliability of three types of ceramic-matrix composites: discontinuously reinforced ceramic-matrix composites, continuous fiber ceramic composites, and carbon-carbon composites. It also presents examples of their mechanical and physical properties. Examples that illustrate the properties of commercially available materials are also provided.

Ceramic-matrix composites (CMCs) are being developed for a number of high-temperature and high-performance applications in industrial, aerospace, and energy conservation sectors. This article focuses on processing, fabrication, testing, and characterization methods of CMCs, namely, discontinuously reinforced composites and continuous-fiber-reinforced composites. Processing methods include cold pressing, sintering, hot pressing, reaction bonding, melt infiltration, directed metal oxidation, sol-gel and polymer pyrolysis, self-propagating high-temperature synthesis and joining. A table summarizes the properties of various ceramic reinforcements and industrial applications of these composites.

This article focuses on the process methods and matrix chemistries of ceramic-matrix composites. These methods include pressure-assisted densification, chemical vapor infiltration, melt infiltration, polymer infiltration and pyrolysis, and sol-gel processing. The article discusses the use of a ceramic, preceramic, or metal phase as a fluid or vapor phase reactant to form the matrix. Emphasis is placed on microstructural features that influence ultimate composite properties.

This article provides a discussion on various types of glasses: traditional glasses, specialty glasses, and glass ceramics. It provides information on glazes and enamels and reviews the broad classes of ceramic materials. These include whitewares, structural clay products, technical ceramics, refractories, structural ceramics, engineering ceramics, and electronic and magnetic ceramics. General processing variables that can affect structure and compositional homogeneity are discussed. Traditional ceramics that include both oxide and nonoxide ceramics are also reviewed. The article concludes with several examples of engineering ceramics.

Carbon-carbon is a unique composite material in which a nonstructural carbonaceous matrix is reinforced by carbon fibers to create a heat-resistant structural material that finds application in the aerospace and defense industries. This article provides a detailed account of the fundamentals of protecting carbon-carbon composites and explains the various coating deposition techniques, namely, pack cementation, chemical vapor deposition, and slurry coatings. It includes information on the practical limitations of coatings for the carbon-carbon composites.

Reinforcing fibers are a key component of polymer-matrix composites (PMCs), ceramic-matrix composites (CMCs), and metal-matrix composites (MMCs). This article discusses the mechanical and nonmechanical properties of these composites. It presents an overview of PMC, CMC, and MMC reinforcing fibers. The article describes cost-considered value-in-use of the ultimate-use temperature of selected fibers in three fiber categories: metal fibers or wires, oxide ceramic fibers, and non-oxide ceramic fibers.

This article describes the manufacture, post-processing, fabrication, and properties of carbon-carbon composites (CCCs). Manufacturing techniques with respect to the processibility of different geometries of two-directional and multiaxial carbon fibers are listed in a table. The article discusses matrix precursor impregnants, liquid impregnation, and chemical vapor infiltration (CVI) for densification of CCCs. It presents various coating approaches for protecting CCCs, including pack cementation, chemical vapor deposition, and slurry coating. Practical limitations of coatings are also discussed. The article concludes with information on the mechanical properties of CCCs.

Carbon-carbon composites (CCCs) are introduced in fields that require their high specific strength and stiffness, in combination with their thermoshock resistance, chemical resistance, and fracture toughness, especially at high temperatures. The use of CCCs has expanded as the price of carbon fibers has dropped and their mechanical properties have increased. This article begins with an overview of the carbon conversion processes, fiber properties and microstructures, and interfacial bonding and environmental interaction of carbon fibers, followed by a detailed discussion on the various techniques available for processing CCCs for specific applications, including preform fabrication (fiber weaving), densification, application of protective coatings, and joining. The article closes with a description of the mechanical and physical properties and applications of CCCs. The main applications of CCCs, in terms of money and mass, are in the military, space, and aircraft industries.

Ceramic-matrix composites (CMCs) have ability to withstand high temperatures and have superior damage tolerance over monolithic ceramics. This article describes important processing techniques for CMCs: cold pressing, sintering, hot pressing, reaction-bonding, directed oxidation, in situ chemical reaction techniques, sol-gel techniques, pyrolysis, polymer infiltration, self-propagating high-temperature synthesis, and electrophoretic deposition. The advantages and disadvantages of each technique are highlighted to provide a comprehensive understanding of the achievements and challenges that remain in this area.

Additives for plastics and elastomers are used to increase the ease of processing and to improve the properties of the final product. Additives improve processing characteristics by increasing lubricity and by stabilizing the polymer. Additives that improve properties include those that decrease static charge development and microbial activity and those that improve flame retardation characteristics, color, light stability, impact resistance, density and mechanical properties. This article focuses on the additives for polymers and elastomers that are used for improving processing--blowing agents, mold-release agents, lubricants, plasticizers, and heat stabilizers--and for improving properties antimicrobials, antioxidants, antistatic agents, colorants, fillers and fiber reinforcements, flame retardants, impact modifiers, light stabilizers, plasticizers, and heat stabilizers. Furthermore, it discusses the method for addition of these additives and the problems faced during compounding.

One of the key attributes of continuous fiber-reinforced ceramic composites (CFCCs) is their ability to undergo inelastic straining upon mechanical loading. This article reviews the mechanics of inelastic deformation and fracture of CFCCs, as needed for the development of damage-tolerant failure prediction methodologies for use in engineering design. It outlines a general framework for the description of fracture in structural materials in the presence of notches and cracks. The article describes the common classes of fracture behavior of CFCCs and presents the constitutive laws needed to describe crack-tip inelasticity. It demonstrates the effects of inelasticity on crack-tip stress fields and addresses the environmental degradation effects on damage tolerance.

Most welding lasers fall into the category of fiber, disc, or direct diode, all of which can be delivered by fiber optic. This article provides a comparison of the energy consumptions and efficiencies of laser beam welding (LBW) with other major welding processes. It discusses the two modes of laser welding: conduction-mode welding and deep-penetration mode welding. The article reviews the factors of process selection and procedure development for laser welding. The factors include power density, interaction time, laser beam power, laser beam diameter, laser beam spatial distribution, absorptivity, traverse speed, laser welding efficiency, and plasma suppression and shielding gas. The article concludes with a discussion on laser cutting, laser roll welding, and hybrid laser welding.

The selection of engineered materials is an integrated process that requires an understanding of the interaction between materials properties, manufacturing characteristics, design considerations, and the total life cycle of the product. This article classifies various engineered materials, including ferrous alloys, nonferrous alloys, ceramics, cermets and cemented carbides, engineering plastics, polymer-matrix composites, metal-matrix composites, ceramic-matrix and carbon-carbon composites, and reviews their general property characteristics and applications. It describes the synergy between the elements of the materials selection process and presents a general comparison of material properties. Finally, the article provides a short note on computer aided materials selection systems, which help in proper archiving of materials selection decisions for future reference.

This article examines the high-temperature oxidation of silica-forming ceramics under constant temperature and cyclic conditions. The effects of water vapor, impurities, and molten salts are discussed. The article describes the oxidation and corrosion of silica-forming composites, oxide ceramics, non-silica forming nitrides, carbides, and borides. The performance of environmental barrier coatings by material type is also discussed. The article also explains the effects of oxidation and corrosion on the mechanical properties of ceramic-matrix composites. It concludes with information on high-temperature applications, wear properties, and the microscopic analyses of advanced ceramics.

This article reviews the applications of traditional glasses in architecture, transportation, construction, houseware, containers, and fibers. It also describes uses of specialty glasses for aerospace and military applications, biomedical and dental applications, chemical-resistant applications, lighting, information display, electronic processing and electronic devices, optical and ophthalmic products, and communications equipment.

Sintering provides the interparticle bonding that generates the attractive forces needed to hold together the otherwise loose ceramic powder mass. It also improves hardness, strength, transparency, toughness, electrical conductivity, thermal expansion, magnetic saturation, corrosion resistance, and other properties. This article discusses the fundamentals of sintering and its effects on pore structures and particle density. It addresses some of the more common sintering methods, including solid-state, liquid-phase, and gas pressure sintering, and presents alternative processes such as reaction sintering and self-propagating, high-temperature synthesis. It also describes several pressure densification methods, including hot isostatic pressing, gas pressure sintering, molten particle deposition, and sol-gel processing. The article concludes with a section on grain growth that discusses the underlying mechanisms and kinetics and the relationship between grain growth and densification.

Laser has found its applications in cutting, drilling, and shock-peening operations of manufacturing industry because of its accurate, safe, and rapid cutting property. This article provides an account on the fundamental principles of laser cutting (thermal), drilling, and shock-peening processes of which emphasis is placed on thermal laser cutting. It details the principal set-up parameters, such as the laser beam output, nozzle design, focusing optic position and characteristics, assist gases, surface conditions, and cutting speed. A discussion on the types of gas, supply system, purity level, and flow rates of lasing and assist gases is also provided. The article also describes the metallurgies and other key material considerations that impact laser-cutting performances and includes examples of laser cutting of nonmetal materials.

This article is intended to assist the development of procedures for the brazing of ceramic-to-ceramic or ceramic-to-metal joints for service under elevated temperatures, mechanical or thermal stresses, or corrosive atmospheres. It describes the factors considered in preparing a procedure for the brazing of graphitic materials.