Metallurgy for Dummies

The Metallurgy's Blog for Beginners 
The Tunguska Event – Meteorite or Comet?
The Tunguska Giant Explosion

A meteorite is a meteoroid (a solid piece of debris from such sources as asteroids or comets) originating in outer space that survives impact with the Earth’s surface. A meteorite’s size can range from small to extremely large. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids. When a meteoroid enters the atmosphere, frictional, pressure, and chemical interactions with the atmospheric gasses cause the body to heat up and emit light, thus forming a fireball, also known as a meteor or shooting/falling star. The term bolide refers to either an extraterrestrial body that collides with the Earth, or to an exceptionally bright, fireball-like meteor regardless of whether it ultimately impacts the surface.

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Nano Welding
Nano Welding Reviews

US researchers have found a new way to weld together metal nanowires – simply by bathing them in white light. The finding could offer a new way to fabricate transparent nanowire meshes for electronic applications in areas such as touchscreens and organic photovoltaics.Erik Garnett and colleagues at Stanford University used a technique called the polyol process to synthesise silver nanowires 30-80nm in diameter and 3-10µm long. The process results in nanowires that are coated in a molecular sheath of polyvinylpyrrolidine (PVP). The nanowires were deposited on a surface randomly by dropping or spraying. This resulted in many of the wires lying over one another in a criss-cross pattern. Due to the layer of PVP where the nanowires cross, a gap of about 2nm exists between them.

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Advanced Ceramics an Introduction
Ceramics an Introduction

The 20th century has produced the greatest advancement in ceramics and materials technology since humans have been capable of conceptive thought. As the limits of metal-based systems are surpassed, new materials capable of operating under higher temperatures, higher speeds, longer life factors and lower maintenance costs are required to maintain pace with technological advancements. Metals, by virtue of their unique properties: ductility, tensile strength, abundance, simple chemistry, relatively low cost of production, case of forming, case of joining, etc. have occupied the vanguard position in regard to materials development. This combination enables large shapes to be made; the Space Shuttle is a typical example of the application of advanced materials and an excellent example of the capability of advanced materials.
It is only during the last 30 years or so, with the advances of understanding in ceramic chemistry, crystallography and the more extensive knowledge gained in regard to the production of advanced and engineered ceramics that the potential for these materials has been realised. This advancement changed the way ceramic systems were viewed.

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History of Forging
What is Forging ?

Forging is one of the oldest known metalworking processes. Traditionally, forging was performed by a smith using hammer and anvil, and though the use of water power in the production and working of iron dates to the 12th century, the hammer and anvil are not obsolete. The smithy or forge has evolved over centuries to become a facility with engineered processes, production equipment, tooling, raw materials and products to meet the demands of modern industry.

In modern times, industrial forging is done either with presses or with hammers powered by compressed air, electricity, hydraulics or steam. These hammers may have reciprocating weights in the thousands of pounds. Smaller power hammers, 500 lb (230 kg) or less reciprocating weight, and hydraulic presses are common in art smithies as well. Some steam hammers remain in use, but they became obsolete with the availability of the other, more convenient, power sources. Forging can produce a piece that is stronger than an equivalent cast or machined part. As the metal is shaped during the forging process, its internal grain deforms to follow the general shape of the part. As a result, the grain is continuous throughout the part, giving rise to a piece with improved strength characteristics.

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Ferrite (iron)
What is Ferrite?

Ferrite also known as alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body-centered cubic crystal structure. It is this crystalline structure which gives steel and cast iron their magnetic properties, and is the classic example of a ferromagnetic material. Practically speaking, it can be considered pure iron. It has a strength of 280 N/mm2 and a hardness of approximately 80 Brinell.
Ferrites are chemical compounds consisting of ceramic materials with iron(III) oxide (Fe2O3) as their principal component. Many of them are magnetic materials and they are used to make permanent magnets, ferrite cores for transformers, and in various other applications.

Mild steel (carbon steel with up to about 0.2 wt% C) consist mostly of ferrite, with increasing amounts of pearlite (a fine lamellar structure of ferrite and cementite) as the carbon content is increased. Since bainite (shown as ledeburite on the diagram at the bottom of this page) and pearlite each have ferrite as a component, any iron-carbon alloy will contain some amount of ferrite if it is allowed to reach equilibrium at room temperature. The exact amount of ferrite will depend on the cooling processes the iron-carbon alloy undergoes as it cools from liquid state.

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What is a Liquid Crystal?
Introduction to Liquid Crystals

Liquid crystals (LCs) are matter in a state that has properties between those of conventional liquid and those of solid crystal. Liquid crystal materials are unique in their properties and uses. As research into this field continues and as new applications are developed, liquid crystals will play an important role in modern technology. This tutorial provides an introduction to the science and applications of these materials. For instance, an LC may flow like a liquid, but its molecules may be orientated in a crystal-like way. There are many different types of LC phases, which can be distinguished by their different optical properties (such as birefringence). When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have distinct textures. The contrasting areas in the textures correspond to domains where the LC molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in an LC phase (just as water may turn into ice or steam).

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Mesoporous Material
What is Mesoporous Material?

Mesoporous materials are defined as natural or synthetic materials having a pore diameter of 2-50 nm, halfway between the pore sizes that define micro- and macroporous materials. They have a large surface area and are particularly useful for applications in catalysis, separation, and absorption. A mesoporous material is a material containing pores with diameters between 2 and 50 nm. Porous materials are classified into several kinds by their size. According to IUPAC notation, microporous materials have pore diameters of less than 2 nm and macroporous materials have pore diameters of greater than 50 nm; the mesoporous category thus lies in the middle. Typical mesoporous materials include some kinds of silica and alumina that have similarly-sized fine mesopores.

Mesoporous oxides of niobium, tantalum, titanium, zirconium, cerium and tin have also been reported. According to the IUPAC, a mesoporous material can be disordered or ordered in a mesostructure. A procedure for producing mesoporous materials (silica) was patented around 1970. It went almost unnoticed and was reproduced in 1997. Mesoporous silica nanoparticles (MSNs) were independently synthesized in 1990 by researchers in Japan. They were later produced also at Mobil Corporation laboratories and named Mobil Crystalline Materials, or MCM-41.

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History of Superconductor
Superconductor

A superconductor is a material that can conduct electricity or transport electrons from one atom to another with no resistance. This means no heat, sound or any other form of energy would be released from the material when it has reached “critical temperature” (Tc), or the temperature at which the material becomes superconductive. Unfortunately, most materials must be in an extremely low energy state (very cold) in order to become superconductive. Research is underway to develop compounds that become superconductive at higher temperatures. Currently, an excessive amount of energy must be used in the cooling process making superconductors inefficient and uneconomical.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.

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What is Metal?
Metal Definition

A metal is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable, ductile and shiny. The meaning of the term “metal” differs for various communities for example, astronomers call for convenience metals everything but hydrogen and helium. Many elements and compounds that are not normally classified as metals become metallic under high pressures.
Metals typically consist of close-packed atoms, meaning that the atoms are arranged like closely packed spheres. Two packing motifs are common, one being body-centered cubic wherein each metal atom is surrounded by eight equivalent atoms. The other main motif is face-centered cubic where the metal atoms are surrounded by six neighboring atoms. Several metals adopt both structures, depending on the temperature.The materials are grouped roughly into two categories, these being “Non-metallic” and Metallic”. In respect to metallic materials these are then subsequently grouped into two groups being ferrous and non-ferrous. Each of the materials has their own characteristics and requires different machining techniques. Careful consideration needs to be given to the correct material selection for its application. (Definition: Ferrous as in containing Iron, e.g steel – Non-ferrous as in not containing Iron e.g aluminium, copper) A simple test for ferrous/non-ferrous materials is to use magnet as a magnet will sick to ferrous materials due to its iron content.

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Sodium (Na)
Natrium

Sodium is a chemical element with the symbol Na (from Latin: natrium) in the periodic table and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. The free metal does not occur in nature, but instead must be prepared from its compounds; it was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Sodium is the sixth most abundant element in the Earth’s crust, and exists in numerous minerals such as feldspars, sodalite and rock salt. Many salts of sodium are highly water-soluble, and their sodium has been leached by the action of water so that chloride and sodium are the most common dissolved elements by weight in the Earth’s bodies of oceanic water.

Sodium is relatively abundant in the sun and other stars. The D lines of sodium are prominent in the solar spectrum. Sodium is the sixth most abundant element on earth. It comprises approximately 2.6% of the earth’s crust. Sodium is the most abundant of the alkali metals. The most common sodium compound is sodium chloride (salt). Sodium occurs in many minerals, such as cryolite, soda niter, zeolite, amphibole, and sodalite. Sodium is not found free in nature. It is obtained commercially by the electrolysis of dry fused sodium chloride.

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Hydrogen Cracking
What is Hydrogen cracking?

Hydrogen cracking also known as cold cracking or delayed cracking. The main feature of this type of crack is that it occurs in ferritic weldable steels, and generally occurs immediately on welding or after a short time after welding, but usually within 48hrs. The mechanism starts with lone hydrogen atoms diffusing through the metal.
At high temperatures, the elevated solubility of hydrogen allows hydrogen to diffuse into the metal (or the hydrogen can diffuse in at a low temperature, assisted by a concentration gradient). When these hydrogen atoms re-combine in minuscule voids of the metal matrix to form hydrogen molecules, they create pressure from inside the cavity they are in. This pressure can increase to levels where the metal has reduced ductility and tensile strength up to the point where it cracks open (hydrogen induced cracking, or HIC). High-strength and low-alloy steels, nickel and titanium alloys are most susceptible. Austempered iron is also susceptible.

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Kevlar
History of Armor

Kevlar is five times stronger than steel but very light weight and half the wieght of fiberglass which made it ideal for making bulletproof vests. It is resistant to impact and abrasion damage. In seawwater its strength is 20 times more than steel which made it excellent for offshore drilling operations. Kevlar is made by Dupont Corporation.Kevlar is a chemical compuned polyparaphenylene terepthalamide which belongs to the class aromatic polyamide is a para-aramid synthetic fibre. Aramides belong to class of nylons. The aramide ring and the para structure is what gives kevlar its high strength and thermal stability. Kevlar was developed in 1965 by Stephanie Kwolek and Roberto Berendt at DuPont Laboratories. Kevlar is a very strong synthetic fiber that can be spun into cloth to make body armor. Kevlar cloth was first used to make body armor in the 1970′s. Kevlar went through a number of government tests until finally a “bullet-resistant” vest was developed.
The marketable vest was crafted from 15 layers of Kevlar cloth and could stop most bullets from common street guns like the 0.38 Special and the 0.22 Long Rifle. The vest was a hit with law enforcement because of its light weight, strength, and ability to wear it under clothes. The Kevlar vest has saved thousands of lives since its invention.

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Pyrometallurgy
Pyrometallurgy Basic Principle

The basic premise of most pyrometallurgical operations is simple: high-temperature chemistry is employed to segregate valuable metals in one phase while rejecting gangue and impurities in another phase. In most instances, both phases are molten (such as the matte and slag in a conventional copper smelting operation). The gas phase may also be used to advantage, either as a means of separating valuable volatile constituents or for removing unwanted volatile impurities. These separation techniques form the basis of thermal smelting and refining operations.
Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals. Pyrometallurgical treatment may produce saleable products such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like Fe, Cu, Zn, Chromium, Tin, Manganese.

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Sandy Superstorm
Hurricane Sandy Superstorm Could Affect 60 Million People

Eastern Time, hitting the southern coast of New Jersey, with its winds slowing slightly to 80 miles an hour from 90 miles an hour earlier, the National Hurricane Center said. By Monday evening, the super storm had already knocked out power to more than 2 million homes and businesses from North Carolina to New England. And a jogger rounding a corner, or cresting a hill, might suddenly come face to face with the true extent of the damage that Monday night’s historic storm had inflicted: cars displaced by the 13ft storm surge that sluiced through Manhattan’s financial district; dangerously damaged power cables; trees wrenched from the ground by the wind; a 700-tonne tanker run aground on the Staten Island shoreline. A state of emergency was declared for Connecticut, Delaware, Washington, D.C., Maryland, Massachusetts, New Jersey, New York, Pennsylvania, Rhode Island and Virginia.

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What is Yield Strength?
Yield strength definition

Yield strength is the stress at which a specified amount of permanent deformation of a material occurs. When we apply stress to a material, it deforms. Some of the deformation is plastic and the material can recover when the stress is relieved. But some deformation is permanent and the material cannot recover from it. As we apply more stress, there is more deformation. This plots on a curve in a somewhat linear, or proportional, way. But at some point, a bit more stress results in a lot more deformation, and this is the proportional limit of the material. Stress applied beyond this causes an increasing rate of deformation until the maximum or ultimate strength of the material is reached. Yield strength is the stress at which a specified amount of permanent deformation of a material occurs.

When we apply stress to a material, it deforms. Some of the deformation is plastic and the material can recover when the stress is relieved. But some deformation is permanent and the material cannot recover from it. As we apply more stress, there is more deformation. This plots on a curve in a somewhat linear, or proportional, way. But at some point, a bit more stress results in a lot more deformation, and this is the proportional limit of the material. Stress applied beyond this causes an increasing rate of deformation until the maximum or ultimate strength of the material is reached.

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What is “Thin Films” materials ?
Advanced Materials : Thin Films

Thin film materials are high purity materials and chemicals used to form or modify thin film deposits and substrates. Examples include precursor gases, sputtering targets, and evaporation filaments. A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction.

Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media and surface coatings. A familiar application of thin films is the household mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface.

The performance of optical coatings (e.g. antireflective, or AR, coatings) are typically enhanced when the thin film coating consists of multiple layers having varying thicknesses and refractive indices. Similarly, a periodic structure of alternating thin films of different materials may collectively form a so-called superlattice which exploits the phenomenon of quantum confinement by restricting electronic phenomena to two-dimensions. Work is being done with ferromagnetic and ferroelectric thin films for use as computer memory.

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Copper Nanoparticles
What are Copper Nanoparticles?
how to weld titanium

Copper (Cu) Nanoparticles are black brown spherical high surface area metal particles. Nanoscale Copper Particles are typically 10-30 nanometers (nm) with specific surface area (SSA) in the 30 – 70 m2/g range and also available in with an average particle size of 70 -100 nm range with a specific surface area of approximately 5 – 10 m2/g.

Nano Copper Particles are also available in passivated and in Ultra high purity and high purity and carbon coated and dispersed forms. They are also available as a nanofluid through the AE Nanofluid production group. Nanofluids are generally defined as suspended nanoparticles in solution either using surfactant or surface charge technology. Nanofluid dispersion and coating selection technical guidance is also available.

Other nanostructures include nanorods, nanowhiskers, nanohorns, nanopyramids and other nanocomposites. Surface functionalized nanoparticles allow for the particles to be preferentially adsorbed at the surface interface using chemically bound polymers. Development research is underway in Nano Electronics and Photonics materials, such as MEMS and NEMS, Bio Nano Materials, such as Biomarkers, Bio Diagnostics & Bio Sensors, and Related Nano Materials, for use in Polymers, Textiles, Fuel Cell Layers, Composites and Solar Energy materials.

Nanopowders are analyzed for chemical composition by ICP, particle size distribution (PSD) by laser diffraction, and for Specific Surface Area (SSA) by BET multi-point correlation techniques. Novel nanotechnology applications also include Quantum Dots. High surface areas can also be achieved using solutions and using thin film by sputtering targets and evaporation technology using pellets, rod and foil.

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What is Scrap Metal?
Scrap Metal

Scrap is a term used to describe recyclable and other materials left over from every manner of product consumption, such as parts of vehicles, building supplies, and surplus materials. Scrap metal originates just as frequently between businesses and homes as well. The proper disposal and recycling of scrap metal is typically done by a business or service. Typically a “scrapper” will advertise his services to conveniently remove scrap metal for people who don’t need it, or need to get rid of it.

The scrap industry contributed $65 billion in 2006 and is one of the few contributing positively to the U.S. balance of trade, exporting $15.7 billion in scrap commodities in 2006. This imbalance of trade has resulted in rising scrap prices during 2007 and 2008 within the United States. Scrap recycling also helps reduce greenhouse gas emissions and conserves energy and natural resources.

For example, scrap recycling diverts 145,000,000 short tons (129,464,286 long tons; 131,541,787 t) of materials away from landfills. Recycled scrap is a raw material feedstock for 2 out of 3 pounds of steel made in the U.S., for 60% of the metals and alloys produced in the U.S., for more than 50% of the U.S. paper industry’s needs, and for 33% of U.S. aluminum. Recycled scrap helps keep air and water cleaner by removing potentially hazardous materials and keeping them out of landfills.

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How to weld titanium

how to weld titanium

Titanium and most titanium alloys are readily weldable, using several welding processes. Properly made welds in the as-welded condition are ductile and, in most environments, are as corrosion resistant as base metal. Improper welds, on the other hand, might be embrittled and less corrosion-resistant compared to base metal.

Commercially pure titanium and most titanium alloys are readily welded by a number of welding processes being used today. The most common method of joining titanium is the gas tungsten-arc (GTAW) process and, secondarily, the gas metal-arc (GMAW) process. Others include electron beam and more recently laser welding as well as solid state processes such as friction welding and diffusion bonding. Titanium and its alloys also can be joined by resistance welding and by brazing.

The techniques and equipment used in welding titanium are similar to those required for other high-performance materials, such as stainless steels or nickel-base alloys. Titanium, however, demands greater attention to cleanliness and to the use of auxiliary inert gas shielding than these materials. Molten titanium weld metal must be totally protected from contamination by air. Also, hot heat-affected zones and root side of titanium welds must be shielded until temperatures drop below 800°F (427°C).

Reaction of titanium with gases and fluxes makes common welding processes such as gas welding, shielded metal arc, flux cored arc, and submerged arc welding unsuitable.Likewise, welding titanium to most dissimilar metals is not feasible, because titanium forms brittle compounds with most other metals; however, titanium can be welded to zirconium, tantalum and niobium.

The techniques for welding titanium resemble those employed with nickel alloys and stainless steels. Molten titanium reacts readily with oxygen, nitrogen and hydrogen and exposure to these elements in air or in surface contaminants during welding can adversely affect titanium weld metal properties. As a consequence, certain welding processes such as shielded metal arc, flux cored arc and submerged arc are unsuitable for welding titanium. In addition, titanium cannot be welded to most other metals because of formation of embrittling metallic compounds that lead to weld cracking.

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Advanced Energy Materials : Supercapacitors!

What is Supercapacitor?

The supercapacitor, also known as ultracapacitor or double-layer capacitor, differs from a regular capacitor in that it has a very high capacitance. A capacitor stores energy by means of a static charge as opposed to an electrochemical reaction. Applying a voltage differential on the positive and negative plates charges the capacitor. This is similar to the buildup of electrical charge when walking on a carpet. Touching an object releases the energy through the finger.

An electric double-layer capacitor (EDLC), also known as supercapacitor, supercondenser, electrochemical double layer capacitor, or ultracapacitor, is an electrochemical capacitor with relatively high energy density. Their energy density is typically hundreds of times greater than conventional electrolytic capacitors. They also have a much higher power density than batteries or fuel cells. A typical D-cell-sized electrolytic capacitor may have capacitance of up to tens of millifarads. The same size EDLC might reach several farads, an improvement of two orders of magnitude. As of 2011 EDLCs had a maximum working voltage of a few volts (standard electrolytics can work at hundreds of volts) and capacities of up to 5,000 farads. In 2010 the highest available EDLC specific energy was 30 Wh/kg (0.1 MJ/kg). The amount of energy stored per unit of mass is called Specific energy, which is often measured in Watt-hour per kilogram (Wh/kg) or MegaJoules per kilogram (MJ/kg). Up to 85 Wh/kg has been achieved at room temperature in the lab, lower than rapid-charging lithium-titanate batteries.

Engineers at General Electric first experimented with the electric double-layer capacitor, which led to the development of an early type of supercapacitor in 1957. There were no known commercial applications then. In 1966, Standard Oil rediscovered the effect of the double-layer capacitor by accident while working on experimental fuel cell designs. The company did not commercialize the invention but licensed it to NEC, which in 1978 marketed the technology as “supercapacitor” for computer memory backup. It was not until the 1990s that advances in materials and manufacturing methods led to improved performance and lower cost.

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What are Alloys?

What is Alloy?

An alloy is a metal composed of more than one element. Engineering alloys include the cast-irons and steels, aluminum alloys, magnesium alloys, titanium alloys, nickel alloys, zinc alloys and copper alloys. For example, brass is an alloy of copper and zinc. An alloy is a metallic substance that is made from the mixture of multiple metals or, sometimes, a metal with some other element such as carbon. Alloys have been around for about nine millennia, but like most other domains in science and technology, the bulk of progress in alloy technology has occurred in the last few decades. In an alloy, the constituent elements are not meant to combine into larger molecules through chemical reactions, but are merely mixed together. When there are different ratios between two or more metals, the alloys produced have slightly different properties. Alloy is a metal made by combining 2 or more metallic elements, especially to give strength or resistance to corroding.

Alloying a metal is done by combining it with one or more other metals or non-metals that often enhance its properties. For example, steel is stronger than iron, its primary element. The physical properties, such as density, reactivity, Young’s modulus, and electrical and thermal conductivity, of an alloy may not differ greatly from those of its elements, but engineering properties such as tensile strength and shear strength may be substantially different from those of the constituent materials. This is sometimes a result of the sizes of the atoms in the alloy, because larger atoms exert a compressive force on neighboring atoms, and smaller atoms exert a tensile force on their neighbors, helping the alloy resist deformation. Sometimes alloys may exhibit marked differences in behavior even when small amounts of one element occur. For example, impurities in semi-conducting ferromagnetic alloys lead to different properties, as first predicted by White, Hogan, Suhl, Tian Abrie and Nakamura.

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What are Nano Materials?

NanoMaterials – a Definition

Nanomaterials are chemical substances or materials that are manufactured and used at a very small scale (down to 10,000 times smaller than the diameter of a human hair). Nanomaterials are developed to exhibit novel characteristics (such as increased strength, chemical reactivity or conductivity) compared to the same material without nanoscale features. Hundreds of products containing nanomaterials are already in use. Examples are batteries, coatings, anti-bacterial clothing etc. Analysts expect markets to grow to hundreds of billions of Euros by 2015. Nano innovation will be seen in many sectors including public health, information society, industry, innovation, environment, energy, transport, security and space Good things come in small packages. the unique properties of nanomaterials and structures on the nanometer scale have sparked the attention of materials developers. Incremental shifts in product performance using these materials–for example, as fillers in plastics, as coatings on surfaces, and as UV-protectants in cosmetics–are already occurring. The technology holds more promise for the future, though, and is expected to bring more disruptive changes to both products and markets.

Nanomaterials is a field that takes a materials science-based approach to nanotechnology. It studies materials with morphological features on the nanoscale, and especially those that have special properties stemming from their nanoscale dimensions. Nanoscale is usually defined as smaller than a one tenth of a micrometer in at least one dimension, though this term is sometimes also used for materials smaller than one micrometer. In comparison to a human hair which is ca. 80,000 nm in diameter, the nanofibers are 1,000 times smaller in diameter. When the characteristic length scale of the microstructure is in the 1- 100 nm range, it becomes comparable with the critical length scales of physical phenomena, resulting in the so-called “size and shape effects.” This leads to unique properties and the opportunity to use such nanostructured materials in novel applications and devices. Phenomena occurring on this length scale are of interest to physicists, chemists, biologists, electrical and mechanical engineers, and computer scientists, making research in nanotechnology a frontier activity in materials science.

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What are Magnesium Alloys?

Magnesium Alloys

Magnesium alloys are mixtures of magnesium with other metals (called an alloy), often aluminium, zinc, manganese, silicon, copper, rare earths and zirconium. Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Magnesium is a silvery-white metal that is principally used as an alloy element for aluminum, lead, zinc, and other nonferrous alloys. Magnesium is among the lightest of all the metals, and also the sixth most abundant on earth. Magnesium is ductile and the most machinable of all the metals. Magnesium has a protective film to protect against corrosion, however it is easily corroded by chlorides, sulfates, and other chemicals, therefore magnesium is often anodized to improve its corrosion resistance.

Magnesium alloy developments have traditionally been driven by aerospace industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium. This has been a major factor in the widespread use of magnesium alloy castings and wrought products. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Therefore magnesium alloys are typically used as cast alloys, but research of wrought alloys has been more extensive since 2003. Cast magnesium alloys are used for many components of modern cars, and magnesium block engines have been used in some high-performance vehicles; die-cast magnesium is also used for camera bodies and components in lenses.

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How to Weld Cast Iron ?

Welding Cast Iron

Welding cast iron has proven to be a very difficult task to do. Many professional welders are sweating hard in determining the best way to weld a stubborn cast iron. Many have tried, many have failed, some had succeeded but the realized that their luck will not turn the next time they weld a cast iron. Cast iron is one of the alloys of iron that has a significant content of carbon in it. The content of carbon varies from about 2% to 4%. This carbon content is about 10 times greater than it is found in other alloys like wrought iron or steel. The cast iron manufacturing process is simple as a result of its simple combination. The reason why cast iron is very complicated to weld is the carbon content that is much higher in the cast iron than other regular irons. Carbon is actually the ingredient that is used in steels and allows it to be heated to make real hard but definitely useful things like razor blades, drill bits, tools and ball bearings.

Cast iron is difficult, but not impossible, to weld. In most cases, welding on cast iron involves repairs to castings, not joining casting to other members. The repairs may be made in the foundry where the castings are produced, or may be made to repair casting defects that are discovered after the part is machined. Mis-machined cast iron parts may require repair welding, such as when holes are drilled in the wrong location. Frequently, broken cast iron parts are repaired by welding. Broken cast iron parts are not unusual, given the brittle nature of most cast iron. Cast irons contains about a full three or four percent carbon, which makes it very hard and vulnerable to weld. Carbon content in cast irons makes the cast iron impossible to dissolve into a metal when it is solidifying from a molten state, and the excess carbon can be found lurking in graphite flakes. These graphite flakes are best for engine blocks and some machine components for they will make lubrication possible in worn surfaces like the cylinder walls. But tough carbon in graphite flakes has its use, which is what makes welding a cast iron very hard.

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What is Malleable Cast Iron?

Malleable Cast Iron – a Definition

Malleable cast iron is produced from white cast iron, which is made from hot liquid iron with certain chemical components. The white cast iron needs to be treated by malleablizing, such as graphitizing or oxidation and decarbonization, then its metallographic structures or chemical components will be changed, so can become into malleable cast iron. Malleable iron is cast as White iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment the brittle as cast structure is transformed. Carbon agglomerates into small roughly speherical aggregates of graphite leaving a matrix of ferrite or pearlite according to the exact heat treat used. Three basic types of malleable iron are recognized within the casting industry, Blackheart malleable iron, Whiteheart malleable iron and Pearlitic malleable iron. Malleable cast iron is a heat-treated iron-carbon alloy, which solidifies in the as-cast condition with a graphite-free structure, i.e. the total carbon content is present in the cementite form (Fe3C). Two groups of malleable cast iron are specified (whiteheart and blackheart malleable cast iron), differentiated by chemical composition, temperature and time cycles of the annealing process, the annealing atmosphere and the properties and microstructure resulting therefrom. The chemical composition of malleable iron generally conforms to the ranges : Small amounts of chromium (0.01 to 0.03%), boron (0.0020%), copper (max 1.0%), nickel (0.5 to 0.8%), and molybdenum (0.35 to 0.5%) are also sometimes present.

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What is Annealing Heat Treatment ?

Annealing of Steel Heat Treatment

Annealing is a heat treatment that alters the microstructure of a material causing changes in properties such as strength and hardness and ductility. Annealed metals are relatively soft and can be cut and shaped more easily. They bend easily when pressure is applied. As a rule they are heated and allowed to cool slowly. Annealing is a heat process whereby a metal is heated to a specific temperature and then allowed to cool slowly. This softens the metal which means it can be cut and shaped more easily. Mild steel, is heated to a red heat and allowed to cool slowly. However, metals such as aluminium will melt if heated for too long. Process Annealing is used to treat work-hardened parts made out of low-Carbon steels (< 0.25% Carbon). This allows the parts to be soft enough to undergo further cold working without fracturing. Process annealing is done by raising the temperature to just below the Ferrite-Austenite region, line A1 on the diagram.

This temperature is about 727 ºC (1341 ºF) so heating it to about 700 ºC (1292 ºF) should suffice. This is held long enough to allow recrystallization of the ferrite phase, and then cooled in still air. Since the material stays in the same phase through out the process, the only change that occurs is the size, shape and distribution of the grain structure. This process is cheaper than either full annealing or normalizing since the material is not heated to a very high temperature or cooled in a furnace. In general, annealing is the opposite of hardening, You anneal metals to relieve internal stresses, soften them, make them more ductile, and refine their grain structures. Annealing consists of heating a metal to a specific temperature, holding it at that temperature for a set length of time, and then cooling the metal to room temperature. The cooling method depends on the metal and the properties desired. Some metals are furnace-cooled, and others are cooled by burying them in ashes, lime, or other insulating materials.

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How does Friction Welding Work?

What is Friction Welding?

Friction welding is a method for making welds in which one component is rotated relative to, and in pressure contact, with the mating component to produce heat at the faying surfaces. The weld is completed by the application of a forge force during or after the cessation of relative motion. Friction welding is a completely mechanical solid-phase process in which heat generated by friction is used to create the ideal conditions for a high integrity welded joint between similar or dissimilar metals. In its simplest form, friction welding involves holding two components in axial alignment. Then rotate them under pressure causing the interface to heat up.

Friction welding (FW) is a class of solid-state welding processes that generates heat through mechanical friction between a moving workpiece and a stationary component, with the addition of a lateral force called “upset” to plastically displace and fuse the materials. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique. However, due to the similarities between these techniques and traditional welding, the term has become common. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.

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What is Carbon Steel?

Carbon Steel – Meaning and Definition

Carbon steel is steel where the main interstitial alloying constituent is carbon. The American Iron and Steel Institute (AISI) defines carbon steel as : “Steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect when the specified minimum for copper does not exceed 0.40 percent or when the maximum content specified for any of the following elements does not exceed the percentages noted : manganese 1.65, silicon 0.60, copper 0.60″. Carbon Steel is a malleable, iron-based metal containing carbon, small amounts of manganese, and other elements to make the material useful for many different applications. Carbon steels are the base metals widely used in manufacturing today around the world in nearly every industry, including aerospace, aircraft, automotive, chemical, and defense.

Carbon steel, also called plain-carbon steel, is a metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. The only other alloying elements allowed in plain-carbon steel are: manganese (1.65% max), silicon (0.60% max), and copper (0.60% max). Steel with a low carbon content has the same properties as iron, soft but easily formed. As carbon content rises the metal becomes harder and stronger but less ductile and more difficult to weld. Higher carbon content lowers steel’s melting point and its temperature resistance in general. The term “carbon steel” may also be used in reference to steel which is not stainless steel, in this use carbon steel may include alloy steels. As the carbon content rises, steel has the ability to become harder and stronger through heat treating, but this also makes it less ductile. Regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the higher carbon content lowers the melting point.

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What is Grey Cast Iron?

Grey Cast Iron – Meaning and Definition

Grey cast iron is characterized by its graphitic microstructure, which causes fractures of the material to have a grey appearance. It is the most commonly used cast iron and the most widely used cast material based on weight. Most cast irons have a chemical composition of 2.5 to 4.0% carbon, 1 to 3% silicon, and the remainder is iron. Grey cast iron has less tensile strength and shock resistance than steel, but its compressive strength is comparable to low and medium carbon steel. Grey cast iron also known as flake graphite cast iron, is a type of casting iron in which most of the carbon is present as flake graphite .The properties of grey cast iron depends on the distribution, sizs and amount of graphite flakes, and the matrix structure. Casting quality are influenced mainly by the manufacturing conditions, chemical composition, solidification time and rate of cooling in the mould.

Grey cast iron exhibits low to moderate strength, low modulus of elasticity, low notch sensitiviy, high thermal conductivity, moderate resistance of thermal stock , and outstanding castability. It is used for housings where tensile strength is non-critical, such as internal combustion engine cylinder blocks, pump housings, valve bodies, electrical boxes, and decorative castings. Grey cast iron’s high thermal conductivity and specific heat capacity are often exploited to make cast iron cookware and disc brake rotors. Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due to its carbide impurities which allow cracks to pass straight through. Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.

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What is Inconel?

Inconel Alloys

Inconel alloys are generally known for their resistance to oxidation and their ability to maintain their structural integrity in high temperature atmospheres. There are several Inconel alloys that are used in applications that require a material that does not easily succumb to caustic corrosion, corrosion caused by high purity water, and stress-corrosion cracking. While each variation of Inconel has unique traits that make it effective in different circumstances, the majority of the alloys are used frequently in the chemical industry.

Inconel is the trade name for a group of more than 20 metal alloys made by Special Metals Corporation. The alloys are extremely resistant to oxidation and high temperatures. Most of the alloys have applications in the chemical industry. Inconel is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys. Inconel alloys are typically used in high temperature applications. It is often referred to in English as “Inco” (or occasionally “Iconel”). Common trade names for Inconel include : Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020.

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