Introduction
Galvannealed steel is preferred to galvanized one in the auto body panels for its improved properties like formability,welability, paintabillity etc. Iron is diffused into the zinc coating during galvannealed treatment. Although, a very high amount of iron in coating is undesirable as it results in a brittle coating that forms high amount of powder at the time of forming[1].Differentintermetallic phases of Fe-Zn system [2]evolve and growwiththe increase in Fe content in coating. These phases differ in iron content, crystal structure and morphology and as a result, they differ in their properties. The overall coating properties are therefore greatly affected by the fraction of these phases in coating. An optimum fraction of these different phases are necessary to achieve the required properties of the coated steel[1].
There are many techniques such as X-ray diffraction (XRD)[3],inductively coupled plasma atomic emission spectroscopy (ICP-OES)[4],colour etching[5]etc. which are used to measure the fraction of different coating phases. Limitations of most of these techniques are the resolution. Electrochemical stripping is one of themethods to characterize coatings with high resolution[4]. In electrochemical stripping anodic dissolution of the coating takes place at constant imposed current. Different phases dissolve at different potential with respect to a reference electrode. From the knowledge of time required for the dissolution at each potential plateaus which corresponds to a single phase, quantification of thickness of different phases is possible with high resolution.
Determination of Fe-Zn intermetallic phase fractions through galvanostatic method is very challenging because of the complex dissolution process....
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...araday’s law. Inthis study true current densities of different phases are measured by the help of the polarization method. It is shown that the coating thickness calculated by the help of true current density results in a reasonably accurate coating thickness prediction of the galvannealed coatings.
Current density calculated from the polarization response of different phases concluded that the deviation of the current density is highest for the delta phase although a fair deviation also exists for gamma phase.
In this method of the use of polarization response to measure the current density of different phases, effect of different factors like presence of cracks, simultaneous dissolution of iron, side reactions are eliminated. However, effect of the continuous formation and breakdown of the corrosion product layer is not addressed here and calls for further study.
The nano-thermal analysis method is capable of studying the specific regions of a sample irrespective of its composition. In a multi-component sample, the analysis methods make it possible for the researchers to distinguish between the different components and identify the different characteristics found in each of the sample (Craig, 2002). During the analysis of any sample, the nano-thermal method does not necessarily require the physical alteration of the sample. In its place, it is capable of analyzing any sample through surface studies.
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.
The objective of this lab is to find the equilibrium constant of Fe(SCN)2+ through multiple trials using a spectrometer. Since one chemical is colorless and the other is colored a spectrometer can be used to monitor amounts of each in the solution. By completing multiple trials an average can be reached for the value of the equilibrium constant of Fe(SCN)2+.
7 Serway, Raymond A., Robert J. Beichner, and John W. Jewett, Jr. Physics for Scientists and Engineers. 5th ed. Philadelphia: Saunders College Publishing, 2000.
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.
The purpose of this experiment was to experimentally determine the equilibrium constant (Kc) for the chemical reaction of Fe3+(aq) + SCN-(aq) ↔ FeSCN2+(aq).
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
Because of its diverse properties, both chemical and physical, zinc oxide is widely used in numerous areas. Among the various potential applications of ZnO that are applicable in today’s industries ranging from rubber to pharmaceutical, from textiles to agriculture, and from electronics and electrotechnology industries. The use of zinc oxide is not limited to only a certain region or area, but rather it is use
The perovskite materials are of considerable technological importance, particularly with regard to physical properties such as pyro and piezoelectricity , dielectric susceptibility, linear and nonlinear optic effects. Many of these properties are gross effects, varying enormously from one perovskite to another and differences in crystal structures are hardly apparent . Effects of the impending transition are evident in some of the crystal properties at temperatures at least a few degrees away from Tc . Substances BaTiO3 and SrTiO3 have very high values of the permittivity due to low frequency of soft mode . It may be inferred that at room temperature BaTiO3 exhibits number of advantages over the other ferroelectrics such as a high mechanical strength , resistance to heat (due to positive temperature coefficient restivity , PTCR ) and moisture , presence of ferroelectric properties with in a broad range of temperature (its Curie point is high ≈ 400 K ) and ease of manufacturing . The presence of an abnormally high permittivity in BaTiO3 is connected with the ‘looseness’ of the crystal lattice of this substance . ( The sum of the atomic radii of titanium and oxygen ions 1.96 is less than the distance between these ions in the lattice 1.99 . The compression of the structure when atom of Ba is replaced by that of Sr drastically reduces dielectric constant and the temperature of the Curie point ) .
In our experiment it’s important to determine some parameters of magnetized plasma. For this purpose, two kinds of optical diagnostics will be used: Interferometry and Polarimetry. Interferometry is used to determine density gradients and thereby the density via Abel Transformation. Polarimetry gives information about the Stokes Components of a laser beam and thereby the Faraday Rotation in order to determine the integrated underlaying B-Field strength. This chapter is focused on polarimetry.
Alford, Terry L., L. C. Feldman, and James W. Mayer. Fundamentals of Nanoscale Film Analysis. New York: Springer, 2007. Print.
Electroplating Experiment Aim To find the amount copper gains or loses on the electrodes using different amounts of current each time during electrolysis. How the changing of current affects the electroplating of copper. Introduction Electroplating is generally carried out in order to improve the appearance or corrosion resistance of the surface of a metal by electrodepositing a thin layer of metal ion on it. The metal substrate to be coated is made by the cathode in an electrolytic cell. The cell used in electroplating contains an electrolyte which is usually an aqueous solution containing a reasonably high concentration of an ion of the metal which is to be electroplated on the surface.
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.
There are 10 types of corrosion, General Attack Corrosion, Localized Corrosion, Galvanic Corrosion, Environmental Cracking, Flow-Assisted Corrosion (FAC), Intergranular corrosion, De-Alloying, Fretting corrosion, High-Temperature Corrosion. General attack corrosion attacks the entire surface of the metal and is caused by chemical or electrochemical reactions (Bell, 2017). Localized corrosion attacks only portions of a metal structure (Bell, 2017). Localized corrosion can be classified as 3 types: pitting, crevice corrosion, and filiform corrosion. Pitting is creating smalls hole in the metal (Bell, 2017). Crevice corrosion occurs in stagnant locations (Bell, 2017). Filiform corrosion happens when water gets under a coating (Bell, 2017). Galvanic corrosion is when two different
The objective of this study is to evaluate the effects of wire length and temperature of wire on electrical conductivity and resistivity.