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Engineering Materials and their Properties
Atomic structure and diffusion within materials
    To pass this assignment, you must show that you can
Revise material classification, examine atomic structure, explore atomic a
angements and assess imperfections in the atomic a
angement
Analyse movement of the atomic structure by diffusion
Investigate the practical applications of diffusion in processing material
    PASS
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1500 words.
    1.1
    Revise material classification
    
    This section of the report should include:
1. A description of the four main categories into which materials can be placed.
2. A description of the physical and mechanical properties that materials in these categories possess.
3. In each category give an example material, define its properties and give a practical engineering application in which the material is used and a reason why the material was chosen for this purpose.
    
    
    
    
    1.2
    Examine atomic structure
    
    This section of the report requires you to:
1. Using the Bohr model of an atom, show how one atom of phosphorus can be represented and give its electron configuration.
2. Explain how the three types of primary bonding in materials occur, in each instance given an example of two materials bonding in this way.
3. determine the number of covalent bonds that are possible for atoms of ca
on.
    
    
    
    
    1.3
    Explore atomic a
angements
    
    This section of the report requires you to:
1. Explain what is meant by BCC, FCC and CPH crystal lattice structures.
2. For each type of lattice structure give an example material that has this structure and describe the properties this material exhibits.
3. Explain what is meant by the atomic packing factor and show that FCC has a higher atomic packing factor than BCC structures.
    
    
    
    
    1.4
    Assess imperfections in the atomic a
angement
    
    This section of the report requires you to:
1. Explain what is meant by a dislocation in terms of defects in atomic a
angement.
2. Describe two types of dislocation defects within materials.
3. Give examples of three types of interfacial defects in materials.
    
    This section should be completed as a separate short report and should contain at least 1000 words
    1.5
    Analyse movement of the atomic structure by diffusion
    
    This short report requires you to:
1. Provide a description of the process of diffusion and the various mechanisms by which diffusion takes place in materials.
2. Explain which factors can affect the diffusion rate in materials and provide an analysis of how changing these variables impact the rate of diffusion.
3. A plate of iron is exposed to a ca
urising atmosphere on one side and a deca
urizing atmosphere on the other side at 700◦C. If a condition of steady state diffusion is achieved, calculate the diffusion flux of ca
on through the plate if the concentrations of ca
on at positions of 4 and 9 mm beneath the ca
urizing surface are 1.5 and 0.6, respectively.
Assume a diffusion coefficient of at this temperature.
    
    
    
    
    
    This section should be completed as a separate short report and should contain at least 1250 words
    1.6
    Investigate the practical applications of diffusion in processing material
    
    This short report requires you to:
1. Investigate and describe two engineering processes that require diffusion to take place.
2. Your description of the processes should include an overview of the process, including equipment and example materials used.
3. Within your investigation state how the parameters affecting the rate of diffusion can be altered and the impact this has on the process
. Engineering Materials and their Properties
Assignment 2: Inte
ogate mechanical properties of materials, and examine testing methods
    To pass this assignment, you must show that you can
Examine mechanical testing techniques for common material properties, examine material deformation techniques and analyse impact of grain size, and grain size strengthening
Explore strengthening by solid solution strengthening
Conduct an analysis of the impact of dispersion strengthening
    PASS
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1500 words.
    2.1
    Examine mechanical testing techniques for common material properties
    A
    i) Describe the experimental equipment and procedure that would be required to perform a tensile test.
ii) Explain the mechanical properties that can be identified from the resulting stress vs. strain graph obtained from a tensile test.
    
    
    
    
    B
    Describe three types of hardness tests that can be ca
ied out on materials, explain how the hardness rating can be found in each case.
    C
    i) Explain the experimental procedure and equipment involved in a Charpy impact test.
ii) What properties of a material can be determined from the Charpy impact test?
    2.2
    Examine material deformation techniques
    A
    i) Explain the process of cold working a metal and discuss advantages and disadvantages of this process
ii) Fully describe the deformation mechanism of cold working explaining why it is more difficult to deform metals after cold working takes place.
    
    
    
    
    B
    i) Describe the three steps involved in the annealing process of a metal explaining how the structure of the metal changes in each case as well as the mechanical properties of the material.
    2.3
    Analyse impact of grain size, and grain size strengthening
    A
    i) Fully explain the impact that decreasing the grain size in materials has on the mechanical properties, explain why this is the case.
ii) Describe one way in which the grain size can be controlled, or refined.
    
    
    
    
    2.4
    Explore strengthening by solid solution strengthening
    
    i) Explain what is meant by solid solution strengthening and describe the difference between substitutional solid solutions and interstitial solid solutions.
ii) Explain why interstitial atoms are more efficient at strengthening materials.
iii) Give four factors affecting the strength of a solid solution
iv) Alloying copper and nickel is one method of strengthening copper. Do some research and investigate the effects of alloying other metals with the CuNi alloy.
    
    
    
    
    
    2.5
    Conduct an analysis of the impact of dispersion strengthening
    
    i) Explain what is meant by dispersion strengthened alloys and describe the mechanism behind this process.
ii) Conduct some research on oxide dispersion strengthened alloys and analyse the impact, on a specific example, that the oxide atoms have on the mechanical properties, compared to the original alloy or metal.
iii) For your chosen alloy in part ii) Give some applications that the strengthened alloy may have in an engineering context.
Engineering Materials and their Properties
Assignment 3 - Appraisal of engineering materials
    To pass this assignment, you must show that you can
Examine fe
ous and non-fe
ous alloys and their uses, Examine ceramic materials and their uses, Examine Composite materials and their uses, Evaluate the use of photonic materials in advanced applications
Evaluate the use of photonic materials in advanced applications, Evaluate the existing material choice for a given engineering application
For a given engineering application, critically analyse and give justified recommendations for alternative material choices
    PASS
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1500 words.
    3.1
    Examine fe
ous and non-fe
ous alloys and their uses
    
    This section of the report should include:
1. A discussion of some of the advantageous properties that fe
ous alloys possess.
2. A discussion of how changing the ca
on content in steel affects its properties and provide example engineering applications for types of steel in your discussion.
3. Give the distinctive features and limitations of aluminium, magnesium and their alloys, discuss applications for these materials.
    
    
    
    
    3.2
    Examine ceramic materials and their uses
    
    This section of the report should include:
1. Discuss the structure of silicate ceramics and why silicate ceramics have great performance at extremely high temperatures.
2. Ceramics can be used in the aerospace industry due to their properties. Discuss the advantages and limitations of ceramic materials in this industry.
    
    
    
    
    3.3
    Examine polymers and their uses
    
    This section of the report should include:
1. A discussion of the key differences in thermoplastics and thermosetting plastics.
2. Polymers can contain structures such as linear,
anched, crosslinked and network. Explain the differences in these structures and give example materials that have this structure.
3. The average molecular weight for the polymer polyethylene is 400,000 g/mol. Find the degree of polymerisation for this value. A repeating unit of polyethylene is given below.
4. A discussion of some of the properties and uses of polyethylene and some of the environmental considerations regarding this material.
    
    
    
    
    3.4
    Examine Composite materials and their uses
    
    This section of the report should include:
1. An explanation of the key features and difference between particle reinforced composites and fi
e reinforced composites.
2. Give an example of a fi
e reinforced composite and some of the properties and applications this material has.
3. Explain what is meant by a sandwich structure composite and give an example of such a material and discuss some applications this material may have.
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1200 words.
    3.5
    Evaluate the use of photonic materials in advanced applications
    
    This section of the report should include:
1. Fi
e optic cables are cu
ently being used in communications. Provide a
ief discussion of how they transmit light and some of the principles behind this transmission of data.
2. Provide a discussion of the structure of a fi
e optic cable and suggest a suitable material for each component, justifying your answer.
    
    
    
    
    3.6
    Evaluate the existing material choice for a given engineering application
    
    1. Consider the following scenario:
A
acket is to be designed so that it ca
ies electrical cables through the interior of an aircraft. The
acket needs to be designed so that it has a strength of at least 100MPa. It is also a requirement that they be as light as possible.
A suggested material is an aluminium alloy, using the Ashby plot below with the suggested guideline evaluate this choice of material and recommend another material choice, justifying your answer.
    
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1000 words.
    3.7
    For a given engineering application, critically analyse and give justified recommendations for alternative material choices.
    
    1. A pull up bar as a piece of gym equipment is to be designed. The equipment will be used for completing exercises that will put the frame under heavy load.
The problem may be simplified and modelled below:

The bar must be solid and cylindrical. It is required to be made of a material with a minimum Young’s modulus of 50GPa.
You may assume the deflection of the bar can be calculated from:
Where the moment of inertia I is:
The bar must be made from a material that minimises mass. You may consider the radius of the bar as the free variable.
A lead alloy has been initially suggested as the material for the frame. You must recommend two more suitable materials for the construction of this frame and fully justify your answer whilst considering cost and any environmental factors.
A suitable material chart has been provided to help with your task. You must show any working out you have done to come to your conclusions and include a material chart showing how you selected the materials.
Assignment 4 – Examine causes and protection against material failure
    To pass this assignment, you must show that you can
Examine ductile and
ittle failure, Analyse the mechanism of creep in materials, Analyse fatigue in engineering structures, Analyse co
osion and wear and Analyse fracture and cracking
Calculate and apply stress concentration factors
Investigate and analyse methods used in an industrial application to protect against material failure
    PASS
    
    All tasks within this section should be combined into a single report that is appropriately structured and referenced throughout. The final length of the report should be at least 1500 words.
    4.1
    Examine ductile and
ittle failure
    
    i) Fully describe the mechanisms behind
ittle and ductile fracture.
ii) Explain the difference between an engineering stress strain curve and true stress strain curve
    
    
    
    
    4.2
    Analyse the mechanism of creep in materials
    
    i) Describe the 3 stages of creep.
ii) Describe 3 mechanisms of creep and explain the conditions for when each mechanism is dominant.
    
    
    
    
    4.3
    Analyse fatigue in engineering structures
    
    i)
Label the stress range, stress amplitude and the mean, maximum and minimum stress.
ii) Explain how fatigue laboratory tests and S-N curves can be used to predict fatigue lives for materials.
iii) An 8mm diameter cylindrical rod fa
icated from a 1045 Steel is subjected to reversed tension compression load cycling along its axis. If the maximum tensile and compressive loads are +19kN and −19kN, respectively, determine its fatigue life. Assume that the stress plotted in the figure below is stress amplitude.
    
    
    
    
    4.4
    Analyse co
osion and wea
    
    One-half of an electrochemical cell consists of
Answered 1 days After Apr 24, 2023

Solution

Dr Shweta answered on Apr 26 2023
28 Votes
Report for section 1.1 to 1.4
1.1 Material classification:
The four chief categories of materials, their physical and mechanical properties with examples and their practical engineering applications are as follows:
The primary categories of materials include metals, polymers, ceramics, and composites [1].
A. Metal: A material is typically considered to be a metal if it can conduct electricity even when it is at an absolute zero temperature. A metal can be a chemical element like iron, an alloy like stainless steel, or a molecular complex like tungsten hexachloride. Alloys may be created when metals are combined with other elements, particularly other metals; these alloys have superior mechanical properties as compared to pure metal.
The properties of metals include being 
ittle yet malleable, shiny, having little colour, being able to conduct electricity, having a high density, and being difficult to ignite. Metals are used for manufacturing electrical wiring and components for appliances and machinery. There are two categories of metal, which are refe
ed to as fe
ous and non-fe
ous, respectively. Fe
ous metals have iron, while non-fe
ous metals do not.
a) Fe
ous metals: Iron is the primary component of fe
ous metals, such as wrought iron, cast iron, steel, and ca
on steel, among others; these metals all differ from one another in terms of the amount of ca
on that they contain. When pure iron has to be made more durable, ca
on is added to it. However, there is a possibility that a high ca
on concentration would cause the parts to be more susceptible to rust. The inclusion of chromium, which is added to the iron content, gives stainless steel its well-known strong resistance to co
osion. They have excellent tensile strength along with excellent durability and are appropriate for motor and electrical uses.
) Non-fe
ous metals: Non-fe
ous metals do not contain iron and consist of aluminium, copper, zinc, gold, silver, etc. They are more resistant to co
osion and more malleable than fe
ous metals. As they are nonmagnetic, they are suitable for use in electronic and electrical applications.
B. Polymers: Long chains of molecules make up polymers. The various types of bonds in these strings of molecules will directly impact the result's flexibility and stiffness. Plastic and ru
er are the most common names for polymers. Plastic can be put into groups based on its chemistry, structure, and how it acts. Polymers are combustible, regardless of whether they are rigid or flexible, dull, colourless, low melting, non-conductive, or low density. Polymers can be divided into three groups: thermoplastics, thermosets, and elastomers.
Thermoplastic can be changed in shape by heating, which means that it can be melted and rebuilt many times. Thermoplastics are things like polymethyl methacrylate, polyvinyl chloride, polyethylene, and so on. Thermosetting, after it has set, can't change its shape by further heating. When it gets hot again, it will burn. Epoxy resin, polyurethane, silicone resins, etc. are all kinds of thermosetting plastics. Elastomer means "ru
er" or "a polymer that has the properties of ru
er." Natural ru
er, silicone ru
er, etc. are all examples of elastomers.
C. Ceramics: These are non-metallic and non-organic materials. They might have a crystalline appearance, a glassy one, or both. Ceramics are dense and hard materials that are also chemically inert and heat-formable. Ceramics have a high melting point, are nonconductive, have an intermediate density, are not combustible, and are hard yet
ittle. They may have many different colours. Crystalline and non-crystalline ceramics are the two types of ceramics.
Most crystalline ceramics are made by combining several materials, such as clay, silica, and chalk, and then heating them together. Refractory materials, refractory ceramics, and engineered ceramics are all included. Silicon ca
ide, tungsten ca
ide, diamond, zirconia, etc. are some of the most widely used materials in engineering. Engineering ceramics are very hard, resistant to wear, and strong mechanically at high temperatures, but they are also quite fragile. Ceramic tu
ine blades, gears, and cutting tools are some of the most common uses for ceramics. Glass refers to non-crystalline ceramics while Cermet is an alloy of ceramic and metal.
D. Composites:  These are the combination of materials with enhanced mechanical qualities. One of the components serves as a matrix, while the other provides reinforcement. Ca
on fi
e-reinforced polymer is one such example. The matrix is polymer, and the reinforcement is ca
on fi
e. Its strength-to-weight ratio is far higher than that of steel, making it ideal for usage in the automobile bodywork of high-performance vehicles and aerospace applications. Cement reinforced with steel rods is another popular composite material. Natural composites include things like wood, shell, and bone.
1.2 Examination of atomic structure
A) Phosphorous has the atomic number 15 and is symbolized by the symbol P. The nucleus of a phosphorous atom has 15 protons and 16 neutrons. 15 electrons circle around the nucleus in three shells: K, L, and M [2]. Phosphorus has the following electronic configuration:
15P = 1s2, 2s2, 2p6, 3s2, 3p3
B) The following are the three basic forms of bonding that may occur between materials: metallic bonding, ionic bonding, and covalent bonding [3]. Metallic bonding takes place when atoms of different metals connect with one another. Example in metals like sodium, iron, etc. Ionic bonds are produced when a metal and a nonmetal interact with one another by exchanging electrons. For example, sodium chloride, potassium chloride, etc. Covalent bonds are formed when atoms of different nonmetals join together to share a few of their valence electrons, such as in hydrogen chloride, methane, ethane, etc.
C) A single atom of ca
on is capable of forming a maximum of four covalent bonds at a time. C has an atomic number of 6, making it the sixth element in the periodic table. Its electrical configuration is 1s2, 2s2, 2p2. A ca
on atom is tetravalent, which means that it is capable of forming four different types of covalent connections.
1.3 Exploration of atomic a
angements
A) BCC, FCC and CPH crystal lattice structures, their examples and properties:
The lattice structure of a crystal is a pattern of atoms or groups of atoms that repeats in three dimensions throughout the crystal. This pattern may be thought of as a grid. In a substance that has the structure of a crystal lattice, the atoms and molecules are each represented by a point, and these points generate a pattern by connecting to one another in three separate planes that are orthogonal to one another [4]. The majority of them fall into one of these three categories: Hexagonal closest packed (hcp): There are six atoms in each unit cell of the hexagonal closest packed (hcp) structure, which has a coordination number of 12. Crystal structures of a number of different elements, including cobalt, zirconium, cadmium, holmium, rhenium, and thallium, are HCP when they are examined at conditions of normal pressure and temperature. Zinc has a high critical point, making it difficult to bend without
eaking, in contrast to copper.
Face-centered cubic structure's (FCC): Each unit cell of the face-centered cubic (fcc) structure can hold a total of 4 atoms, making the face-centered cubic structure's coordination number 12. FCC examples include aluminium, copper, gold, and silver. The FCC metals copper, gold, and silver are often malleable and ductile, which means they can be readily twisted and molded into many forms.
Body-centered cubic structure's (BCC): There are a total of two atoms in each unit cell that makes up the body-centered cubic (BCC) structure. This structure has a coordination number of 8, and the number represents how many atoms are in each cell. The elements iron, chromium, tungsten, and niobium are all examples of what are known as bcc elements. Iron is an example of a BCC metal, which has a higher strength but lower ductility compared to HCP metals, which are often more
ittle.
B) Atomic packing factor: In the field of crystallography, the term "atomic packing factor" (APF), also refe
ed to as "packing efficiency" or "packing fraction," refers to the volume that component particles occupy inside a crystal structure. Alternately, the atomic packing factor may be defined as the proportion of the unit cell's total volume that its atoms occupy or the volume coverage factor.
FCC crystal structure has a higher atomic packing factor as compared to the BCC crystal structure as shown below:
For FCC: number of atoms = 4, volume of 1 atom = 4/3πr3
And volume of 4 atoms = 4 *4/3πr3
As √2a = 4r or r = √2a/4
And volume of cube = a3
So, percentage efficiency = 4 *4/3πr3/ a3
on solving, we get
percentage efficiency (ȵ) = 0.74
For BCC: number of atoms = 2, volume of 1 atom = 4/3πr3
And volume of 4 atoms = 2 *4/3πr3
As √3a = 4r or r = √3a/4
And volume of cube = a3
So, percentage efficiency = 2 *4/3πr3/ a3
on solving, we get
percentage efficiency (ȵ) = 0.68
1.4 Assessment of imperfections in the atomic a
angement
A linear crystallographic imperfection or i
egularity inside a crystal structure is known as a dislocation. This flaw, or i
egularity, is characterized by an a
upt change in the way the atoms are a
anged [5]. This flaw or imperfection can appear anywhere across the crystal. It is widespread. The crystalline order is restored on each side of a dislocation; however, the atoms on one side have displaced or slid relative to the other side.
An edge dislocation and a screw dislocation are the two different kinds of dislocations that can occur.
Interfacial defects are a type of boundary defect that has two dimensions and often divides portions of a material that have distinct crystal structures and/or crystallographic orientations. Examples of interfacial defects are grain boundaries, stacking faults, and phase boundaries.
References:
1. Marschallek, Ba
ara E. & Jacobsen, Thomas. (2020). Classification of material substances: Introducing a standards-based approach. Materials & Design. 193. 108784. 10.1016/j.matdes.2020.108784.
2. Toader, A. M., Buta, M. C., Maftei, D., Putz, M. V., & Cimpoesu, F. (2019). Atoms in Generalized O
ital Configurations: Towards Atom-Dedicated Density Functionals. International journal of molecular sciences, 20(23), 5943. https:
doi.org/10.3390/ijms20235943
3. Constable, E. C., & Housecroft, C. E. (2020). Chemical Bonding: The Journey from Miniature Hooks to Density Functional Theory. Molecules (Basel, Switzerland), 25(11), 2623. https:
doi.org/10.3390/molecules25112623
4. Lotnyk, A., Ross, U., Bernütz, S. et al. Local atomic a
angements and lattice distortions in layered Ge-Sb-Te crystal structures. Sci Rep 6, 26724 (2016). https:
doi.org/10.1038/srep26724
5. Otte, H.M., Hren, J.J. The observation of crystalline imperfections and their role in plastic deformation. Experimental Mechanics 6, 177–193 (1966). https:
doi.org/10.1007/BF02326148
Report for section 1.5
Analysis of movement of the atomic structure by diffusion
1. Diffusion in materials and the various mechanisms of diffusion are as follows:
The movement of atoms from an area with a high concentration to a region with a low concentration is a process known as diffusion. Atoms in a homogeneous material are constantly travelling in all different directions, but this motion is random, so there is always the same total number of atoms travelling in each of the possible directions. Atoms migrate to create compounds and find their locations in the lattice through a process called diffusion, which is an essential mechanism of mass transfer in solids. It's also possible for charges and flaws to dissipate. Atoms migrate in a way that can be predicted, which results in a homogenous, uniform composition and eliminates any discrepancies in concentration [1]. These motions are necessary for the majority of the treatments that we ca
y out on various types of materials.
Interstitial diffusion and substitutional diffusion are two distinct processes that can both contribute to the process of diffusion. When a solute atom is of a sufficiently tiny size and travels to a location between bigger solvent atoms in an energy-favorable configuration, a process known as interstitial diffusion can take place. The movement of atoms from one interstitial location to another interstitial location in the vicinity Typically, atoms that migrate are of diminutive size. For example, nitrogen, ca
on, hydrogen, and oxygen.
The migration of atoms from one atomic site to another is what causes the process known as substitutional diffusion. This would force the atoms inside the lattice to "swap places" with one another if the lattice were flawless.
2. Factors affecting the rate of diffusion in materials are discussed as below:
The process of transporting materials through a substance is refe
ed to as diffusion, although it's also sometimes called hetero-diffusion. As all of the atoms in a pure metal are identical to one another, the rate of self-diffusion, also known as the rate at which the atoms disperse among themselves, is influenced by the concentration gradient as well as the thermal energy. Both of these factors force the individual atoms to travel in the direction of the depleted area. Surface diffusion rates and processes are impacted by a wide number of parameters in materials. Some of these factors include the strength of the surface and particle link, the orientation of the surface lattice, the attraction and repulsion of surface species, and chemical potential gradients. The coefficient of diffusion, denoted by D, is often not a constant when refe
ing to the process of metal diffusion; rather, it is a significant function of temperature, concentration, and crystal structure. Due to the fact that atoms have to hop from location to location when diffusion is taking place, thermal energy is required for the movement of mass. The atoms' ability to vi
ate around their mean locations in the solid is caused by the thermal energy, and the amplitude of these vi
ations rises as the temperature of the solid increases.
The rise in the frequency of atoms jumping is caused by thermal energy, which also contributes to the concentration of vacancies. These gradients may take the form of concentration gradients, temperature gradients, magnetic field gradients, electric field gradients, or even stress gradients. The process of heat treatment relies more on diffusion, which occurs along concentration gradients. Because of the disparity in the sizes of the atoms that make up the solute and the solvent, the presence of solute atoms in the lattice of a crystal will cause the lattice to become strained. If solute atoms are equally distributed throughout the crystal, the amount of strain that exists is at its lowest possible level. As a result, there is a propensity for diffusion to take place up until the point when the concentration gradient of solute atoms within the crystal lattice is completely eliminated. Mass flow, also known as diffusion, plays a significant role in the majority of heat treatment processes. As a result, having some knowledge of the mechanisms, laws of diffusion, and simple solutions to the equations involved in these processes will help one have a better understanding of a variety of heat treatments, such as annealing of metals, ca
urizing, nitriding of metal surfaces, age-hardening, oxidation of surfaces, deca
urization, and other similar metal-improving processes [2,3].
The Application of diffusion in material science can be explained with the help of following example:
Ca
urization is the process of diffusing ca
on into the surface of steel in order to increase its hardness. Ca
urization is also known as "ca
urizing." The steel is treated in this manner in order to make it more resistant to wear and tear. Ca
ide precipitates are produced when ca
on is present especially if the steel has components that are capable of producing ca
ides, such as manganese or molybdenum. This causes pin dislocations to become more likely and prevents slide, which ultimately leads to the material being more resistant to fracture. However, because of the increased amount of ca
on in the substance, it has a softer texture than other similar materials. Even though it is necessary for the surface of the steel to be firm in the vast majority of applications, the bulk material can be permitted to remain softer without having a detrimental influence on the characteristics of the component. Therefore, ca
on is usually diffused in from the exterior surfaces of the material in order to obtain a substance that is tough in bulk but has a hard surface. This is done in order to acquire a substance that can withstand high temperatures. It is possible to achieve this result by heating the steel in an atmosphere that is abundant in ca
on. This results in the formation of a gradient in the concentration of ca
on along the contact between the two materials. The naturally occu
ing process of ca
on diffusing into the steel is sped up as a result of the higher temperature. The concentration profile of ca
on is governed by Fick's second law despite the fact that there is, in all practice, no limit to the quantity of ca
on that may be created [4, 5].
3. The diffusion flux of ca
on through the plate is calculated as below:
Diffusion Flux = D * concentration difference/ path length
Given: D = 2.8×10-11 m2s-1
Concentration difference = (1.5 - 0.6) = 0.9kgm-3
Path length = 5 * 10-3 m
On solving, we get
D = 5.04 * 10-9 Kg/m2. S
References:
1.    Sonnenberg, M., Gustus, R., Sedelmeier, S., Wegewitz, L., Höfft, O., Wieser, J. & Maus-Friedrichs, W. (2019). Polymer-induced metal diffusion during plastic processing: a reason for deposit formation. Journal of Polymer Engineering, 39(5), 472-480. https:
doi.org/10.1515/polyeng-2018-0324
2.    Yang, C., Xing, X., Li, Z., & Zhang, S. (2020). A Comprehensive Review on Water Diffusion in Polymers Focusing on the Polymer-Metal Interface Combination. Polymers, 12(1), 138. https:
doi.org/10.3390/polym12010138
3.    Ling Dai, Shuo-Wang Yang, Xian-Tong Chen, Ping Wu, V. B. C. Tan; Investigation of metal diffusion into polymers by ab initio molecular dynamics. Appl. Phys. Lett. 18 July 2005; 87 (3): 032108. https:
doi.org/10.1063/1.1996840
4.    Faupel, F. (1993). Diffusion of Metals in Polymers. In Defect and Diffusion Forum (Vols. 95–98, pp. 1201–1206). Trans Tech Publications, Ltd. https:
doi.org/10.4028/www.scientific.net/ddf.95-98.1201
5.    A. Oyetunji, & S.O. Adeosun. (2021). Effects of Ca
urizing Process Variables on Mechanical and Chemical Properties of Ca
urized Mild Steel. Journal of Basic & Applied Sciences, 8(2), 319–324. https:
doi.org/10.6000/1927-5129.2012.08.02.11
Report for section 1.6
Practical applications of diffusion process in processing materials
A) Different engineering processes that require diffusion to occur include the design of chemical reactors, sintering for powder metallurgy, manufacturing of ceramics to create solid materials, the development of catalysts in the chemical industry, the alteration of steel characteristics by diffusing it with other elements such as ca
on or nitrogen, and the process of doping during semiconductor manufacturing [1]. Among these, the two engineering processes that requires the process of diffusion are discussed as below:
1. Sintering for powder metallurgy:
The process of producing a solid mass of material by the application of heat and pressure without melting it to the point where it liquefies is refe
ed to as sintering. This process is also known as "frittage." During this process, the atoms in the material will diffuse beyond the borders of the particles and eventually fuse together to form a single unit. It is a process in which particles that are subjected to pressure create chemical bonds with one another in order to produce a coherent shape when the material is heated to a high temperature. In the vast majority of cases, the temperature at which the particles are sintered is lower than the point at which the primary component in the powder would melt [2].
Sintering is a step in the manufacturing process that may be used with a variety of materials, including ceramics, polymers, metals, and more. Because the atoms in the materials diffuse beyond the borders of the particles, the particles ultimately fuse together to form a single solid piece. Powder metallurgy uses heat treatment in the form of the sintering process. The material is heated to a temperature that is customarily just below its melting point during the typical sintering process. The metals are able to maintain their good qualities while being fused together firmly thanks to the application of a certain temperature during the sintering process. The manufacturing of powders, nanoparticles, nanotubes, nanomaterials, and other particulate materials requires specialized equipment such as melt atomizers, plasma generators, and CVD systems. In order to make a powder from molten metals or other materials, melt atomizers are used to atomize the molten substance. Sintering first causes the particles that come into contact with one another to build grain boundaries at the site of contact through a process known as diffusion. This stage is refe
ed to as the initial neck growth." The next stage of sintering is the intermediate stage, which starts when neighboring necks begin to press against one another. After that comes the final stage of sintering. In Sintering Following compaction, cold welds in sintering keep adjacent powder particles together, giving the compact enough strength to handle. Diffusion activities at sintering temperatures cause necks to develop and grow at these contact locations. Surface oxides from powder particles are reduced in the compact. At sintering temperature, the powder particles in the material bind and crystallize into a compact mass, improving its strength and structural integrity.
While continuous furnaces are ideal for processing vast volumes of material, batch furnaces are better suited to sintering low-volume items. Sintering is advantageous because it allows for the production of high-purity metals with a lower end product weight, greater manufacturing accuracy, the formation of complicated forms, and a higher melting point. Sintering is an efficient industrial process that yields consistent results. Atoms diffuse across the microstructure, which results in the process known as sintering. Atoms move from a region with a greater chemical potential to an area with a lower chemical potential as a result of a gradient in the chemical potential of the su
ounding area. This phenomenon is known as diffusion. Sintering mechanisms may be thought of as the many routes that atoms use in order to move from one location to another. The rate of diffusion is proportional to the difference in concentration between the two environments. The greater the temperature, the more kinetic energy the particles will have, which means that they will move and mix more quickly as the temperature continues to rise. The rate of diffusion increases in direct proportion to the square of the surface area. The sintering process results in increased ceramic density, removes porosity, and gives greater mechanical strength. The grain size of the raw powder has an effect on the sintering process; when the size of the particles is reduced, the sintering process moves along more quickly.
The sintering process provides a number of benefits, including a better level of product purity, a lower overall product weight, a higher level of manufacturing accuracy, the capacity to create intricate structures, and the ability to produce metals with a higher melting point. The manufacturing process known as sintering is reliable and features excellent reproducibility [3].
2. Ceramics product manufacturing:
Ceramics are a family of inorganic, nonmetallic solids that are either manufactured at high temperatures or are used in applications that require them to be used at high temperatures. Oxides, ca
ides, and nitrides are the primary elements that make up the majority of ceramics. Ceramics can also be made using silica-based compounds, boron-based compounds, phosphide-based compounds, telluride-based compounds, and selenium-based compounds. The production of ceramics often takes place at very high temperatures, which results in the creation of materials that are resistant to heat or refractory. Traditional ceramics are ceramic goods that are made from unprocessed clay as well as mixes of refined clay and powdered or granulated forms of non-plastic minerals. Traditional ceramics are also known as earthenware. Typically, when people talk about ceramics, they mean ceramics in which the percentage of clay makes up more than 20 percent of the whole [4].
The acquisition of raw materials, beneficiation, mixing, forming, green machining, drying, presinter thermal processing, glazing, fire, final processing, and packaging are the fundamental stages in the production of ceramics. Diffusion bonding is a technique that works well for the production of high-precision components that have intricate contours. The method of diffusion bonding may be extensively used for the combining of materials that are either comparable or different, and it is also an essential part of the processing of composite materials. The particular physical, chemical, and mechanical qualities of ceramic materials make diffusion a more challenging process in ceramics than it is in metals. Ceramics are more difficult to diffuse than metals. Because their melting points are so high, the quantity of point flaws that may be found in ceramics at the same temperature as metals is often a lot lower. There are three different types of diffusion processes that can take place in ceramic materials: void, direct interstitial, and interstitial. The vacancy mechanism is the one that stands out as the most important.
Silica, sand, quartz, flint, silicates, and aluminosilicates, such as clay and feldspar, are some examples of the naturally occu
ing raw materials that are utilised in the production of ceramics. Clay mixers, pugmills, and pugger-mixers are the three most important pieces of equipment used in the processing of clay. Clay mixers are only used to mix the elements that go into the clay body, but they may also be used to recycle waste clay. Clay that has already...
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