What Is Corrosion?
Corrosion may be defined as the deterioration of a material due to a reaction with the environment around it. Metals corrode because we use them in environments that are chemically unstable. Very few metal are found in nature in their metallic state such as copper, gold and silver . All other metals are processed from minerals or ores into metals which are innately unstable in their environments. These unstable metals have a tendency to revert to their more stable mineral forms. Some metals form protective ceramic films (passive films) on their surfaces and these prevent, or slow down, their corrosion process. We can prevent corrosion by using metals that form naturally protective passive films, but these alloys are usually expensive, so we have developed other means of corrosion control. That are discussed later in this paper.
Types Of Corossion
There are two common classifications of corrosion: direct chemical attack and electrochemical attack. In both cases the metal is converted into a compound such as a sulfate, oxide, or hydroxide. Corrosion always involves two concurrent changes. The metal that is oxidized suffers what is called anodic change, and the corrosive agent is reduced and is undergoing cathodic change.
Direct chemical attack, is corrosion resulting from direct contact of a bare surface to caustic liquid or gaseous substance. Unlike electrochemical attack where the anode and cathode changes may be happening at a distance, the changes in direct chemical attack are taking place at the same time and at the same point. The most common substances causing direct chemical attack on an aircraft are; residual flux deposits resulting from inadequately cleaned, welded, brazed, or soldered joints, spilled b...
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...luminum. There are many kinds of stainless steels. That are generally immune to corrosion, but they may crevice corrosion and undergo stress corrosion cracking in some cases.
Titanium is a common metals in nature, but its limited use means that small-scale production results in a high price. However it finds extensive use in the aerospace industry. There are two general types of titanium alloys-aerospace alloys and corrosion resistant alloys.
Engineering designers must consider how much metal is necessary to withstand the anticipated load for a given application. Since they can make mistakes, or the structure can be misused, they are required to over design the aircraft by a safety factor. Once the necessary mechanical load safety factor has been considered, it becomes necessary to consider whether what corrosion allowance is necessary to keep the aircraft safe.
Combined with corrosion fatigue” (“Silver”).
We use metals to construct all kinds of structures, from bridges to skyscrapers to elevators. The strength as well as durability of materials that are crafted out of metal make the materials ideal not only for construction but also for many other applications.
Metal alloys and precious metals are also used to make certain aspects of a cochlear implant. The electrode arrays that provide electrical stimulation in order to excite neurons are made out of platinum because they have very high corrosion resistance, good biocompatibility, easier to work with than iridium and have low chemical reactivity. On the other hand, metallic alloys like titanium are used to make the casing for the receiver/stimulator. Titanium is suitable for such an application because it is a light material with high corrosion resistance and rigidity and these properties are essential for the material that is going to be used to make the casing (Stöverl and Lenarz, 2009).
A wide variety of coating alloys and wrought alloys can be prepared that give the metal greater strength, castability, or resistance to corrosion or high temperatures. Some new alloys can be used as armor plate for tanks, personnel carriers, and other military vehicles.
Titanium carbide (TiC) is a titanium compound that is used for it hardness. TiC is used to produce cutting tools. The strength of titanium avails it to be used to cut and to engrave other metals which are not as hard as titanium.
Metals contain a sea of electrons (which are negatively charged) and which flow throughout the metal. This is what allows electric current to flow so well in all metals. An electrode is a component of an electric circuit that connects the wiring of the circuit to a gas or electrolyte. A compound that conducts in a solution is called an electrolyte. The electrically positive electrode is called the anode and the negative electrode the cathode.
Titanium shows a high strength-weight ratio and has exceptional corrosion resistance. Titanium alloys have received considerable interest recently due to their wide range of applications in the aerospace, automotive and medical industries. The most common titanium alloy is Ti6Al4V, which belongs to the α+ β alloy group. However titanium alloys are difficult to machine due to their low modules of elasticity. Titanium is a poor conductor of heat, its thermal conductivity is about 1/6 that of steel. Heat, generated by the cutting action, does not dissipate quickly; therefore, most of the heat is concentrated on the cutting edge and the tool face [1]. Titanium has a strong alloying tendency or chemical reactivity with materials in the cutting tools and also reacts with oxygen and nitrogen in air at tool operating temperatures. This causes galling, welding, and smearing along with rapid destruction of the cutting tool [1].
Stainless steel is a type of alloy that has a very strong lattice structure (an arrangement/ shape of the crystals or other objects) which in some case can be more beneficial than others depending on the type of application it may be used for. In many cases this structure will make the material more suited to being used in engineering applications such as tools for instance a hammer (stainless steel alloys) , also they can be used for gears, engines, electrical motors and hydraulic systems because the structure makes the material so strong. So when the arrangement of the structure is as above it makes the overall material even stronger which makes it a good for all the applications stated above. I believe its strength and durability are its main properties as these are commonly needed in the engineering industry, although it is also very well known to be used for its corrosion resistance as it is resistant to many types of corrosion. It is used for these properties because the components such as gears need to be strong in order to keep transferring and altering the rotary motion and torque exhibited in the machine that it may be used in, durable to withstand any loads or pressure put onto it and also corrosion resistance to give the components a bigger life span and increase its rate of work throughout its required use.
Elements, corrode when in proximity with liquid; water and oxygen, these compounds and elements are mandatory for corrosion to occur. Corrosion is a result from oxidation; when an element corresponds with oxygen. For example when the element;...
The important thing in titanium is not only light but also very strong so it can be used for making vehicles which will consume less fuel and we can
Aluminum is the most abundant metal and the third most abundant element in the earth's crust, after oxygen and silicon. It makes up about 8% by weight of the earth’s solid surface. Aluminum also chemically reactive to occur naturally as the free metal (Kobayashi et al, 2002). There are many applications of Aluminum in our daily life, such as construction machinery, aircraft construction, ship construction, home furnishing and electronics component. For the vehicle industry, Aluminum has established a worldwide position because of its advantages over the other competitive materials, like light weight, providing exceptional unit strengths (strength/density ratio), high corrosion resistance, low maintenance costs, good temperature resistance (even in arctic environments), ductile, easily joined by all commercial processes such as welding, brazing, or soldering, at the last, aluminum can be easily formed by all common processes, including extrusion (a major advantage) and can be recycled.
Roman slaves extracted and prepared the lead, describes a disease among the slaves that was clearly lead poisoning. Because of their potential toxicity, lead water pipes are no longer being installed. The greatest single use of lead metal today is in the plates of storage batteries for automobiles. The protective oxidation layer formed by lead in contact with such substances as air, sulfuric acid, and fluorine makes it highly resistant to corrosion. For this reason, lead has been used to make drainage pipes and lead chambers in sulfuric acid factories.
Aluminum is an element in the boron group with a symbol of Al, and an atomic number of 13. Aluminum is a very soft metal when pure but becomes strong and hard when alloyed, a malleable metal with a silvery gray color. Aluminum is a very reactive element so it is found in nature combined with other elements. Aluminum resists corrosion by the formation of a self-protecting oxide coating. Aluminum is the third most abundant element in the Earth’s crust, following oxygen and silicon. It makes up approximately 8% by weight of the Earth’s surface. Although this is evident, it is also apparent that aluminum is never found by itself in nature. All of the earth’s aluminum has combined with other elements to form compounds and in order to create new aluminum products; it has to be taken out of that specific compound. Aluminum does not rust like other elements, therefore it always remains strong and shiny, which means reused aluminum is almost identical to a brand new piece of metal. An electrochemical process creates aluminum. An electrochemical process is “the direct process end use in which electricity is used to cause a chemical transformation” ( E.I.A. Government). Major uses of electrochemical processes occur in the aluminum industry in which alumina is reduced to molten aluminum metal and oxygen, where than the aluminum can be used into making several different materials. Electrochemical processes, although very useful, can have serious environmental consequences. To help reduce the consequences that the production of aluminum creates, the idea of aluminum recycling comes into play.
Metals possess many unique fundamental properties that make them an ideal material for use in a diverse range of applications. Many common place things know today are made from metals; bridges, utensils, vehicles of all modes of transport, contain some form of metal or metallic compound. Properties such as high tensile strength, high fracture toughness, malleability and availability are just some of the many advantages associated with metals. Metals, accompanied by their many compounds and alloys, similar properties, high and low corrosion levels, and affects, whether negative or positive, are a grand force to be reckoned with.
Toughness is the ability of a metal to mutilate plastically and to absorb energy in the process before it breaks or fracture. Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. This can be done by using heat treatment processes which include precipitation strengthening, quenching, annealing and tempering. Annealing and tempering are the most prominent methods for treating metals. A material may become more or less brittle, harder or softer, or stronger or weaker, depending on the treatment used.