Metals 101:Common and new materials in manufacturing. Materials science gives us new ways to produce materials suitable for engineering requirements in several aspects: the hardness, temperature level, high energy utilization and cost savings. For example, manufactures who need to respond to all kinds of engineering problems in different environmental conditions where the material should stand in temperature change, corrosive environment and drilling tools that can penetrate through the hardest materials. In this article, we will introduce the most commonly used family of materials: Composed materials, alloy Steels and Ceramic materials. A good example for materials industry can come by looking at the steel industry in the United States of America, American Standard and manufactured are building skyscrapers and bridges only with iron and thus actually created whole cities are built on this raw material. Steel is a remarkable material which gives us great engineering reliability and immunity thanks to its great difficulties. What is carbon fiber? Carbon fiber is a thin filament (stand) comprising of sheets of carbon atoms arranged in hexagonal pattern aligned along the axis of the filaments length. Carbon fiber is also sometimes called graphite fiber. The diameter of the filament is mostly in the range of 5 to 10 microns. Thousands of these filaments or stands of carbon fiber are put together to form tow or yarn/ the yarn is combined with epoxy resins and other thermosetting materials to form various composite materials for varied applications ranging from aerospace to windmills to sporting goods. Properties: Carbon fiber has a remarkably high strength and light weight compared to other traditional materials. It can be produced with very high modulus for applications such as spacecraft, arms etc. It is flexible in structural design, it has chemical resistivity and to corrosion. It has good thermal properties and electric conductivity. Application: Carbon fiber has proven to be extremely useful as reinforcement material to produce composite materials .Carbon fiber can be applied in components wherever Light weight and high strength is required such as: air craft body and other parts, wind mill blades, military applications, decorations, tennis rackets and more… What is tungsten carbide? The main use of tungsten (in the form of tungsten carbide) is now in the manufacture of cemented carbide. Cemented carbide, or hard metal as it is often called, is a material made by "cementing" very hard tungsten monocarbide (WC) grains in a binder matrix of tough cobalt metal by liquid phase sintering. The combination of WC and metallic cobalt as a binder is a well-adjusted system not only with regard to its properties, but also because of the sintering behavior of the materials. The high solubility of WC in cobalt at high temperatures and a very good wetting of WC by the liquid cobalt binder result in an excellent densification during liquid phase sintering and in a pore-free structure. As a result of this, a material is obtained which combines high strength, toughness and high hardness. Properties: There are two well characterized compounds of tungsten and carbon, WC and tungsten semi carbide, W2C. Both compounds may be present in coatings and the proportions can depend on the coating method. At high temperatures, WC decomposes to tungsten and carbon, this can occur during high-temperature thermal spray, e.g., in high velocity oxygen fuel (HVOF) and high energy plasma (HEP) methods. Oxidation of WC starts at 500–600 °C. It is resistant to acids and only attacked by hydrofluoric acid/nitric acid (HF/HNO3) mixtures above room temperature. It reacts with fluorine gas at room temperature and chlorine above 400 °C (752 °F) and is uncreative to dry H2 up to its melting point. WC dissolves readily in diluted hydrogen peroxide. Application: Based on the wide range of grain sizes now available, not only very hard and abrasion resistant, but also very tough, hard metals can be produced for widespread applications in high tech tools, wear parts and mining tools as well as for many sectors of the engineering industry. There has been a rapid development in mining and stone cutting tools, with improved performance which has led to the increasing substitution of steel tools by cemented carbide tools, in particular in the oil industry. Notably, the use of very coarse grained hard metals is growing in this application area. A special application for these fine or ultrafine WC hard metals, involving large quantities of cemented carbide, is in drills for the drilling of the very fine holes in printed circuit boards for the computer and electronic industries. For this purpose, new cemented carbide compositions, based on extremely fine-grained carbide, have been introduced. What is Aluminum T70-75: Aluminum T70-75 underwent an aging process (hardness by melting). This process gives the aluminum alloy a high hardness property in relation to pure Aluminum. In addition it gives a high ratio between strength and density. This alloy is useful for many applications. Properties: Very high strength material used for highly stressed structural parts. The T7351 temper offers improved stress-corrosion cracking resistance. Applications: Aircraft fittings, gears and shafts, fuse parts, meter shafts and gears, missile parts, regulating valve parts, worm gears ,keys, aircraft, aerospace and defense applications. Bike frames, all terrain vehicle (ATV) sprockets. What is stainless steel? Stainless steels play an important role in the modern world, even if its tonnage represents only about 2% of the whole steel production. Austenitic stainless steels (ASSs) were invented in Essen, Germany, in the beginning of the 20th century and represent today more than 2/3 of the total stainless steel world production. Their continuing development has resulted in complex steel compositions with substantial amounts of alloying elements. These alloying elements are of course introduced in the steel for one or more reasons but the final aim is mainly to obtain better mechanical properties (especially high creep strength and high creep-rupture ductility) and/or higher corrosion resistance (especially oxidation resistance in the case of high temperature application). As usual, the benefits of such additions invariably come attached to unavoidable disadvantages of which the most important are the potential micro structural instability and difficult processing of the material. Properties: The two main requirements that materials aimed at high temperature applications should comply with are oxidation and creep resistance. Equipment or components exposed to high temperatures are susceptible to several external attacks such as oxidation, carburization, sulfidation, nitridation, halogen gas corrosion, ash or salt deposit corrosion, molten salt corrosion and molten metal corrosion. Oxidation is the most important high-temperature corrosion reaction the temperature range for which different ferrous materials presents a satisfactory oxidation resistance. As expected, the maximum temperature raises with the steel chromium content. The basic mechanism involves the formation of a Cr2O3 and/or a FeCr2O4 spinel protective film. Addition of rare-earth elements to alloys produces a substantial increase in their resistance to high-temperature oxidation. Recently, a group of Al2O3 – forming austenitic stainless steels (Fe-20Ni-14Cr-2.5Al) has been developed. Alumina-base protective scales present better performance than Cr2O3, especially in the temperature range of interest (between 600 and 850 °C). Application: Stainless steels resistance to corrosion and staining, low maintenance and familiar luster make it an ideal material for many applications. There are over 150 grades of stainless steel, of which fifteen are most commonly used. The alloy is milled into coils, sheets, plates, bars, wire, and tubing to be used in cookware, cutlery, household hardware, surgical instruments, major appliances, industrial equipment (for example, in sugar refineries) and as an automotive and aerospace structural alloy and construction material in large buildings. Storage tanks and tankers used to transport orange juice and other food are often made of stainless steel, because of its corrosion resistance. This also influences its use in commercial kitchens and food processing plants, as it can be steam-cleaned and sterilized and does not need paint or other surface finishes .Stainless steel is used for jewelry and watches with 316L being the type commonly used for such applications. It can be re-finished by any jeweler and will not oxidize or turn black. Some automotive manufacturers use stainless steel as decorative highlights in their vehicles. Conclusions: Presented in this paper are the main common materials in use by the industry and their applications. As shown, the applications were numerous and varied in different areas of Expertise which Indicates that this field will only grow in influence in the future. When development in science and new materials are making a great revolution, the field gives us a real place to put out our values and Ideology through exciting scientific discoveries that can make a big change in the human industry and in whole aspect of life. Written by: Ziv Kojokaro B.S.c Material Engineering
Posted on: Tue, 11 Jun 2013 15:55:05 +0000
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