Search Results for carbon

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.

Hardenability is a composition-dependent property of steel and depends on carbon content and other alloying elements as well as the grain size of the austenite phase. This article provides an overview of a wide range of testing procedures used to determine and quantify hardenability of shallow-hardening, low-carbon, plain carbon, and low-alloy medium-carbon steels ranging from classical fracture and etching, Grossmann hardenability, and Jominy end-quench testing to manual and computerized computational methods. The article then uses this as a backdrop for the implementation of the core concepts of hardenability in a variety of predictive tools for calculating hardenability. The Caterpillar 1E0024 Hardenability Calculator, a personal computer-based program, calculates the Jominy curve based on the steel composition. The article also describes the method for boron and nonboron steels, with calculation examples for 8645 steel and 86B45 steel.

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.

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.

This article presents an overview of the material properties of carbon-carbon composites. It provides information on the applications of carbon-carbon composites in electronic thermal planes, spacecraft thermal doublers, spacecraft thermal shields, spacecraft radiators, and aircraft heat exchangers.

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.

This article is a compilation of binary alloy phase diagrams for which carbon (C) is the first named element in the binary pair. The diagrams are presented with element compositions in weight percent. The atomic percent compositions are given in a secondary scale. For each binary system, a table of crystallographic data is provided that includes the composition, Pearson symbol, space group, and prototype for each phase.

This article is a compilation of ternary alloy phase diagrams for which carbon (C) is the first-named element in the ternary system. The other elements are Co, Cr, Cu, Fe, Mn, Mo, N, Ni, S, Si, Ti, V, and W. The diagrams are presented with element compositions in weight percent. The article includes 136 phase diagrams (solidus projection, liquidus projection, isothermal section and vertical section).

This article is a collection of two iron-carbon phase diagrams.

Carbon arc welding (CAW) utilizes a nonconsumable electrode, made of carbon or graphite, to establish an arc between itself and either a workpiece or another carbon electrode. This article describes the operation modes of the CAW process: single-electrode operation and twin-electrode operation. It presents a schematic representation of typical arrangements for single-electrode and twin-electrode carbon arc welding. Recommended current ranges for carbon and graphite electrodes are listed in a table. The article concludes with information on the applications of the CAW process.

This article describes the influence of steel chemical compositions and microstructure on machining processes. It discusses the various microstructural phases of standard carbon and alloy steels, which influence machinability. The article reviews the expected response of several traditional machining operations, such as turning, drilling, milling, shaping, thread cutting, and grinding, to the microstructure of standard steel grades. It also explains the technologies in non-traditional machining processes, such as abrasive waterjet cutting, electrical chemical grinding, and laser drilling.

The production and use of steel plate is aided by a system of standard designations and associated specifications defining composition, property, and performance ranges. This article contains an extensive amount of information on the designations and grades of plate products and how they are made. Although most steel plate is used in the hot-finished condition, some applications require one or more heat treating steps to mitigate imperfections and/or improve relevant qualities. The article discusses these interconnected factors as well as their impact on mechanical properties and critical fabrication issues, including formability, machinability, and weldability.

Carbon steels have wider usage than any other metal because of their versatility and low cost. Required hardenability is the most important factor influencing a choice between carbon- and alloy steel. By increasing hardenability, alloying elements extend the potential for enhanced properties to the large sections required for many applications. Alloy steels are ordinarily quench hardened and tempered to the level of strength desired for the application. Distortion during heat treatment may occur with almost any hardenable carbon or alloy steel, although distortion is usually more severe for carbon grades than for alloy grades of equivalent carbon content. The relatively low hardenability of carbon steels is a primary reason for choosing them in preference to alloy steels for parts that are to be locally heat treated by flame or induction hardening. Fabrication processes are performed on hardenable carbon and alloy steels in the unhardened condition, that is, prior to heat treating.

Hardenability of steel is the property that determines the depth and distribution of hardness induced by quenching. Hardenability is usually the single most important factor in the selection of steel for heat-treated parts. The hardenability of a steel is best assessed by studying the hardening response of the steel to cooling in a standardized configuration in which a variety of cooling rates can be easily and consistently reproduced from one test to another. These include the Jominy end-quench test, the carburized hardenability test, and the air hardenability test. Tests that are more suited to very low hardenability steels include the hot-brine test and the surface-area-center test. The article discusses the effects of varying carbon content as well as the influence of different alloying elements. It includes charts and a table that serve as a general steel hardenability selection guide.

This article addresses classifications and designations for carbon steels and low-alloy steels, particularly high-strength low-alloy (HSLA) steels, based on chemical composition, manufacturing methods, finishing method, product form, deoxidation practice, microstructure, required strength level, heat treatment and quality descriptors. It describes the effects of alloying elements on the properties and characteristics of steels. The article provides extensive tabular data pertaining to domestic and international designations of steels.

This article discusses the following physical properties of AISI and SAE grades of carbon and low-alloy steels: coefficients of linear thermal expansion; thermal conductivity; specific heat; and electrical resistivity.

This article addresses classifications and designations for carbon and low-alloy steel sheet and strip product forms based on composition, quality descriptors, mechanical properties, and other factors. Carbon steel sheet and strip are available as hot-rolled and as cold-rolled products. Low-alloy steel sheet and strip are used primarily for applications that require the mechanical properties normally obtained by heat treatment. The descriptors of quality used for hot-rolled plain carbon steel sheet and strip and cold-rolled plain carbon steel sheet include structural quality, commercial quality, drawing quality, and drawing quality, special killed. The surface texture of low-carbon cold-rolled steel sheet and strip can be varied between rather wide limits. The modified low-carbon steel grades discussed in the article are designed to provide sheet and strip products having increased strength, formability, and/or corrosion resistance. The article also summarizes the key operations involved in the three alternative direct casting processes: thin slab, thin strip, and spray casting.

This article briefly reviews the production methods and characteristics of plain carbon and low-alloy water-atomized iron and steel powders, high-porosity iron powder, carbonyl iron powder, and electrolytic iron powder. It emphasizes on atomized powders, because they are the most widely used materials for ferrous powder metallurgy. The article provides information on the properties and applications of these powders. It also includes an overview of diffusion alloying, basics of admixing, and bonded premixes.

This article discusses the classifications, compositions, properties, advantages, disadvantages, limitations, and applications of the most commonly used methods for surface engineering of carbon and alloy steels. These include cleaning methods, finishing methods, conversion coatings, hot-dip coating processes, electrogalvanizing, electroplating, metal cladding, organic coatings, zinc-rich coatings, porcelain enameling, thermal spraying, hardfacing, vapor-deposited coatings, surface modification, and surface hardening via heat treatment.

This article reviews various phases and constituents found in the microstructures of low-carbon and coated steels. It provides information on the criteria for selecting proper metallographic procedures. Techniques used to prepare metallographic specimens of low-carbon steels and coated steels, such as sectioning, mounting, grinding, polishing, and etching, are discussed. The article also reviews the simple and proven manual sample preparation techniques of coated steel specimens.