New DM308 Materials
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What is the purpose of annealing glass within a long cooling tunnel?

  • To increase the temperature of the glass for shaping
  • To melt the glass completely
  • To gradually cool the glass and prevent residual stresses (correct)
  • To introduce bubbles into the glass

    • Which method is used to produce very thin glass sheets?

  • Fusion forming (correct)
  • Melting Powder Refining
  • Melt glass
  • Blow moulding

    • At what temperature is the glass melt cooled to give the correct viscosity for a float bath?

  • ~1100°C (correct)
  • ~500°C
  • ~1600°C
  • ~2000°C

    • What is the main advantage of the 'overflow and down-draw method' over the float bath method?

    <p>Produces flatter and more uniform thickness glass sheets</p> Signup and view all the answers

    What is the displacement vector needed to close a circuit around the dislocation line called?

    <p>Burgers vector</p> Signup and view all the answers

    Which type of dislocation has its Burgers vector perpendicular to the dislocation line?

    <p>Edge dislocation</p> Signup and view all the answers

    What phenomenon is responsible for the plastic deformation of crystalline material?

    <p>Dislocation glide</p> Signup and view all the answers

    What determines the yield strength of a material by indicating the minimum stress required for dislocation glide?

    <p>Critical resolved shear stress (CRSS)</p> Signup and view all the answers

    In an FCC crystal, what type of planes host unique close-packed slip directions?

    <p>{111}-type planes</p> Signup and view all the answers

    How many unique close-packed {111}-type planes are found in an FCC crystal?

    <p>4</p> Signup and view all the answers

    Which type of directions link lattice sites in an FCC crystal?

    <p>{111}-type directions</p> Signup and view all the answers

    Why are FCC crystals considered comparatively plastic?

    <p>Due to high number of slip systems</p> Signup and view all the answers

    What type of strengthening does Zinc provide in Aluminum alloys?

    <p>Solution strengthening</p> Signup and view all the answers

    In Al alloys, what type of mechanical properties are controlled by work hardening?

    <p>Strength and hardness</p> Signup and view all the answers

    What do white blobs indicate in the context of Al alloy deformation?

    <p>Nucleation sites of recrystallized grains</p> Signup and view all the answers

    How does cryogenic deformation affect the strength of aluminum alloys?

    <p>Increases strength at the expense of ductility</p> Signup and view all the answers

    What does cold rolling do to the strength of an aluminum alloy?

    <p>Substantially increases it</p> Signup and view all the answers

    Which element can be exploited to improve strain hardening in aluminum alloys based on the information provided?

    <p>Magnesium (Mg)</p> Signup and view all the answers

    What is the primary mechanism that slows down dynamic recovery in aluminum alloys?

    <p>Cellular structure formation</p> Signup and view all the answers

    Which process can substantially increase both UTS and yield stress in an aluminum alloy?

    <p>Cold rolling</p> Signup and view all the answers

    Which coating process is faster but results in a rougher and more porous coating?

    <p>Plasma spraying</p> Signup and view all the answers

    What property makes technical ceramics suitable for high-temperature applications?

    <p>High stiffness</p> Signup and view all the answers

    In terms of hardness and wear resistance, how do most technical ceramics compare to metal alloys and polymers?

    <p>Considerably harder with excellent wear resistance</p> Signup and view all the answers

    What property does CFRP (ceramic-reinforced polymer) possess in terms of density compared to technical ceramics?

    <p>Lower density</p> Signup and view all the answers

    Which material is primarily an electrical insulator with moderate thermal conductivity?

    <p>Ceramics</p> Signup and view all the answers

    What property allows technical ceramics to have the highest specific stiffness and specific strength?

    <p>Low density</p> Signup and view all the answers

    What can be said about precipitate-free zones (PFZ)?

    <p>They act as stress concentrators.</p> Signup and view all the answers

    How can the width of precipitate-free zones be controlled?

    <p>By heat treatment and alloying.</p> Signup and view all the answers

    Why are grain boundaries considered good sites for precipitate formation?

    <p>Since they provide faster solute diffusion and nucleation sites.</p> Signup and view all the answers

    What effect does cold work have when used in conjunction with the heat treatment for ageing in Al alloys?

    <p>Allows a coarser but more uniform precipitate distribution.</p> Signup and view all the answers

    How does the protective oxide film on aluminium contribute to its corrosion resistance?

    <p>By forming a barrier against further corrosion.</p> Signup and view all the answers

    What happens when aluminium is in contact with an electrolyte and a less reactive metal?

    <p>It acts as a sacrificial anode and corrodes rapidly.</p> Signup and view all the answers

    What property is not covered in this course?

    <p>Conductivity</p> Signup and view all the answers

    What is the relationship between force and extension in Hooke's law?

    <p>Force is directly proportional to extension</p> Signup and view all the answers

    In tension, the strain in a material is:

    <p>Always positive</p> Signup and view all the answers

    What type of testing machine is commonly used for stress-strain testing?

    <p>Hydraulically actuated</p> Signup and view all the answers

    What is the main difference between tensile and compressive stresses?

    <p>Tensile stresses are positive; compressive stresses are negative</p> Signup and view all the answers

    What property does Hooke's law aim to derive that is independent of spring shape?

    <p>Force constant k</p> Signup and view all the answers

    Positive strain occurs in which situation?

    <p>Tension</p> Signup and view all the answers

    What is the main purpose of a binder additive in technical ceramics?

    <p>Ensures cohesion of the ceramic powder in the green parts</p> Signup and view all the answers

    What is a characteristic property of lead glass?

    <p>Absorption of radiation</p> Signup and view all the answers

    Which process is used to adjust the properties of ceramic powder by decreasing viscosity and increasing particle concentration?

    <p>Dispersing</p> Signup and view all the answers

    Which application is NOT associated with the use of Bioglass?

    <p>Solar heat collectors</p> Signup and view all the answers

    What stage involves the removal of the binder from ceramic parts before sintering?

    <p>Binder removal</p> Signup and view all the answers

    What sets glass ceramics apart from traditional glasses?

    <p>Controlled crystallization</p> Signup and view all the answers

    What is the primary function of lead oxide in lead glass?

    <p>Lower the melt viscosity</p> Signup and view all the answers

    What is the primary function of a dispersant additive in technical ceramics processing?

    <p>Reduces viscosity of the mixture</p> Signup and view all the answers

    Why are bioglasses formulated to be chemically similar to hydroxyapatite?

    <p>To enhance mineral growth in bones</p> Signup and view all the answers

    In technical ceramics production, what does green machining refer to?

    <p>Machining ceramics in their unfired state</p> Signup and view all the answers

    What is the primary function of granulating in technical ceramics processing?

    <p>Creating cohesive green parts for moulding/forming</p> Signup and view all the answers

    What role does the negative thermal expansion coefficient of crystalline phases play in glass ceramics?

    <p>Contributes to net zero thermal expansion</p> Signup and view all the answers

    Which stage of technical ceramics processing involves adjusting ceramic properties by milling or turning?

    <p>Finishing</p> Signup and view all the answers

    What makes the crystalline phase in glass ceramics unique in terms of thermal expansion?

    <p>Negative thermal expansion coefficient</p> Signup and view all the answers

    How does bioglass promote the growth of new bone tissue?

    <p>&quot;Stimulates formation of hydroxyapatite&quot;</p> Signup and view all the answers

    What is the purpose of plasticising in technical ceramics processing?

    <p>Enhancing the plasticity of ceramic mixtures</p> Signup and view all the answers

    In the context of ceramics, which stage involves the shaping of the material into the desired form?

    <p>Forming/shaping</p> Signup and view all the answers

    What is a typical application of ceramics involving the creation of high-temperature structural components?

    <p>Creating refractories and crucibles</p> Signup and view all the answers

    When was the first man-made glass most likely produced?

    <p>3000 BCE</p> Signup and view all the answers

    What was the status of glass as a material during the Roman Empire?

    <p>Luxury material</p> Signup and view all the answers

    Which natural material containing glass-like properties has been used by people since prehistoric times to make tools and artefacts?

    <p>Obsidian</p> Signup and view all the answers

    During which historical period did glass usage expand to include building materials like stained glass windows?

    <p>Middle Ages</p> Signup and view all the answers

    'Knapping' as a technique has been applied to which glass-like natural material by people since prehistoric times?

    <p>Obsidian</p> Signup and view all the answers

    What is the primary difference between the 2xxx and 6xxx series aluminum alloys mentioned in the text?

    <p>The primary intermetallic phases present</p> Signup and view all the answers

    Which Al alloy series is known for being used in aircraft rivets even today?

    <p>2017</p> Signup and view all the answers

    What property led to the development of alloys like 2618 for supersonic aircraft?

    <p>Creep resistance</p> Signup and view all the answers

    Which alloy series is primarily recognized for having the most complex precipitation processes?

    <p>6xxx</p> Signup and view all the answers

    What is the distinguishing feature of Al-Mg-Si alloys in terms of strength?

    <p>Correlated with magnesium and silicon content</p> Signup and view all the answers

    Which property do 2xxx series aluminum alloys possess in addition to high strength?

    <p>Excellent corrosion resistance</p> Signup and view all the answers

    Why are Al-Cu-Mg alloys like Duralumin no longer widely used today?

    <p>Replaced by newer derivative systems with higher strength</p> Signup and view all the answers

    Which element plays a significant role in providing medium strength in Al-Cu, Al-Cu-Mg, and Al-Zn-Mg-Cu alloys?

    <p>3.5</p> Signup and view all the answers

    Which type of glass is used to immobilize highly radioactive nuclear waste?

    <p>Borosilicate glass</p> Signup and view all the answers

    What is the process of turning molten glass into flat glass sheets called?

    <p>Vitrification process</p> Signup and view all the answers

    What is the role of tin in the Pilkington float glass process?

    <p>Increases thermal conductivity</p> Signup and view all the answers

    Which glass type was produced by glass-blowers before the nuclear age and fluoresces under UV light?

    <p>Lead glass</p> Signup and view all the answers

    What is an essential characteristic of uranium glass made before the nuclear age?

    <p>High thermal conductivity</p> Signup and view all the answers

    Which type of ceramic system is used in applications like cooktops and fireplaces?

    <p>Borosilicate ceramic</p> Signup and view all the answers

    What is the purpose of vitrification in dealing with highly radioactive waste?

    <p>To create a water-soluble formulation</p> Signup and view all the answers

    What is a distinctive feature of glass ceramics compared to traditional glasses?

    <p>High thermal expansion coefficient</p> Signup and view all the answers

    What is the purpose of HIP-ing in additive manufacturing?

    <p>To reduce the porosity of products</p> Signup and view all the answers

    In slip casting, what happens when the plaster absorbs moisture from the adjacent slip?

    <p>The slip becomes more viscous</p> Signup and view all the answers

    What is the primary function of a doctor blade in tape casting?

    <p>To adjust the height of the ceramic tape</p> Signup and view all the answers

    Which method allows mass production of ceramics with very complex relief?

    <p>Slip casting</p> Signup and view all the answers

    What is the key advantage of gel-casting for technical ceramic forming?

    <p>Enables a high degree of precision and complex geometries</p> Signup and view all the answers

    What is formed in freeze casting using a suspension of ceramic particles in water?

    <p>Gel-like material</p> Signup and view all the answers

    What is the primary difference between ceramics and glass in terms of their natural occurrence?

    <p>Ceramics occur in minerals like obsidian, while glass occurs in fused sand.</p> Signup and view all the answers

    What was the significance of glass during the middle ages?

    <p>It was commonly used as a building material for stained glass windows.</p> Signup and view all the answers

    What was one of the first uses of man-made glass?

    <p>Incidental production during metal-working processes.</p> Signup and view all the answers

    In what way did the Roman Empire contribute to the adoption of glass as a more common material?

    <p>By using glass extensively in architecture and interior design.</p> Signup and view all the answers

    What technological advancement enabled the widespread use of full glass windows?

    <p>Advancement of modern plate glass technologies.</p> Signup and view all the answers

    What natural event can lead to the formation of glass from sand?

    <p>Lightning strike</p> Signup and view all the answers

    What technique was used by people since prehistoric times to shape materials like obsidian?

    <p><strong>Knapping</strong></p> Signup and view all the answers

    Why was glass considered a luxury material until its adoption in the Roman Empire?

    <p><strong>Because of the high production costs involved.</strong></p> Signup and view all the answers

    What is the main focus in developing superplastic behavior in high-strength 7xxx series alloys?

    <p>Reducing forming strain rates</p> Signup and view all the answers

    What is a common feature of cast Al alloys in applications such as anodizing and engine blocks?

    <p>Impurities from recycled stock</p> Signup and view all the answers

    Why is the ratio of cast aluminum to wrought constantly increasing?

    <p>Increased use of castings in automotive industry</p> Signup and view all the answers

    Which type of aluminum castings are divided into 'primary' and 'secondary' categories based on their material source?

    <p>Alloys prepared from recycled metals</p> Signup and view all the answers

    In 2004, what was the Cast:Wrought ratio in USA automotive use?

    <p>1:2</p> Signup and view all the answers

    What is a distinguishing factor between 'primary' and 'secondary' cast aluminum alloys?

    <p>Impurity levels</p> Signup and view all the answers

    Which application is a common end-use for Al-Si, Al-Si-Mg, and Al-Si-Cu systems?

    <p>Transmissions casings</p> Signup and view all the answers

    What is the purpose of the primary ageing treatment in the heat treatment process of turbine blades?

    <p>To grow the desired distribution of g’ precipitates</p> Signup and view all the answers

    What is a common issue that may lead to a blade being scrapped during directional solidification?

    <p>Secondary Grains</p> Signup and view all the answers

    What is the main purpose of depositing TBC on turbine blades?

    <p>Effusion cooling</p> Signup and view all the answers

    Why are the heat-treated blades subjected to further finishing and quality control procedures post-casting?

    <p>For heat treatment to optimize microstructure</p> Signup and view all the answers

    Which possible casting defect can result from low-angle grain boundaries?

    <p>Freckles</p> Signup and view all the answers

    What is the main purpose of Neutron Radiograph in the context of turbine blades?

    <p>Machine blade to shape and perform NDT</p> Signup and view all the answers

    What is the purpose of HIP-ing in additive manufacturing?

    <p>Reducing porosity of products</p> Signup and view all the answers

    What distinguishes tape casting from slip casting in ceramic production?

    <p>Tape casting produces thin ceramic tapes or sheets</p> Signup and view all the answers

    Which method is known for allowing a high degree of precision in forming highly advanced technical ceramics?

    <p>Sol-gel processing</p> Signup and view all the answers

    What happens during freeze casting in terms of the suspension used?

    <p>Ceramic particles are suspended in water</p> Signup and view all the answers

    What is the main function of the doctor blade in the tape casting process?

    <p>Adjusting the thickness of the ceramic tape</p> Signup and view all the answers

    Which stage in gel-casting involves filling complex molds with a specific substance?

    <p>Polymerization reaction</p> Signup and view all the answers

    How does slip casting enable mass production of ceramics with intricate designs?

    <p>By allowing drying to a 'leather dry' state</p> Signup and view all the answers

    In which method does a gel form to bind ceramic particles before drying and sintering?

    <p>Gel-casting</p> Signup and view all the answers

    What is a distinguishing feature of bioglass mentioned in the text?

    <p>Water solubility</p> Signup and view all the answers

    What sets lead glass apart from regular glassware in terms of composition?

    <p>Additional lead oxide</p> Signup and view all the answers

    What is a primary application of glass ceramics mentioned in the text?

    <p>Production of materials with net zero thermal expansion</p> Signup and view all the answers

    What property of glass ceramics allows for the growth of new bone tissue as mentioned in the text?

    <p>Negative thermal expansion coefficient</p> Signup and view all the answers

    What is a common use of lead glass not mentioned in relation to its toxicity?

    <p>Optics</p> Signup and view all the answers

    Which type of glass has evidence of toxicity and poor thermal shock resistance?

    <p>Lead glass</p> Signup and view all the answers

    What makes traditional glasses different from glass ceramics in terms of thermal expansion?

    <p>Glass ceramics have negative thermal expansion coefficient</p> Signup and view all the answers

    Which element in bioglass becomes part of the growth of new bone tissue within the body?

    <p>$CaO$</p> Signup and view all the answers

    What process increases the strength of a material by creating fine particles with a stronger crystal structure within the parent crystal?

    <p>Precipitation hardening</p> Signup and view all the answers

    In polycrystalline materials, why are grain boundaries important for strength?

    <p>They hinder atomic diffusion</p> Signup and view all the answers

    Which mechanism involves dislocations either cutting through particles or bypassing them to increase material strength?

    <p>Orowan bowing</p> Signup and view all the answers

    What is the parameter used to quantify the obstacle to dislocation motion in a material?

    <p>APB energy</p> Signup and view all the answers

    What type of crystallographic defects are formed when polycrystalline materials consist of mis-oriented grains?

    <p>Grain boundaries</p> Signup and view all the answers

    In the context of materials science, what is the significance of the Burgers vector?

    <p>It represents dislocation magnitude and direction</p> Signup and view all the answers

    How do fine particles formed through precipitation hardening affect dislocation glide?

    <p>They act as obstacles</p> Signup and view all the answers

    Which phenomenon arises when dislocations must cut through particles or bypass them via Orowan bowing?

    <p>Precipitate pinning</p> Signup and view all the answers

    Which lecture in the course is likely to cover the topic of defects in the atomic structure of materials?

    <p>Lecture 4 Properties and processing of ceramics</p> Signup and view all the answers

    Which book could be most helpful for understanding the engineering aspects of materials?

    <p>Engineering materials - Ashby and Jones</p> Signup and view all the answers

    Which type of materials are likely to be discussed in Lecture 5 of the course?

    <p>Glass materials</p> Signup and view all the answers

    Which alloy type is typically known for its application in high-temperature environments?

    <p>Superalloys</p> Signup and view all the answers

    What is a common characteristic shared by ceramics, glasses, and light alloys?

    <p>High temperature resistance</p> Signup and view all the answers

    What distinguishes light alloys from high-temperature alloys?

    <p>Heat resistance</p> Signup and view all the answers

    Which process is crucial for enhancing specific stiffness and specific strength in technical ceramics?

    <p>Sintering</p> Signup and view all the answers

    Which boron nitride form has the second-highest hardness after diamond?

    <p>Cubic boron nitride (c-BN)</p> Signup and view all the answers

    What is a key application of Silicon Nitride (Si3N4) mentioned in the text?

    <p>High-temperature structural parts</p> Signup and view all the answers

    What distinguishes Boron Nitride Nanotubes (BNNTs) from Carbon Nanotubes (CNTs)?

    <p>Flammability in air</p> Signup and view all the answers

    What is the primary use of hexagonal boron nitride (h-BN) as mentioned in the text?

    <p>High-temperature lubricants</p> Signup and view all the answers

    Which material offers moderate properties at a moderate cost in various applications?

    <p>Silicon Nitride (Si3N4)</p> Signup and view all the answers

    What makes cubic Boron Nitride (c-BN) suitable for grinding wheels and abrasives?

    <p>Second-highest hardness after diamond</p> Signup and view all the answers

    Why might Silicon Nitride (Si3N4) be chosen over other ceramics and metals for certain applications?

    <p>Moderate properties at a moderate cost</p> Signup and view all the answers

    What is a method mentioned in the text to refine the grain size of an aluminum casting?

    <p>Creating more grain nuclei by breaking up dendrites during solidification</p> Signup and view all the answers

    Which term describes the property of semi-solid slurries where their viscosity decreases with stirring?

    <p>Thixotropic</p> Signup and view all the answers

    What is the difference between rheocasting and thixoforming?

    <p>Rheocasting requires expensive specialized billets, while thixoforming allows the use of existing alloys.</p> Signup and view all the answers

    What is a characteristic of aluminium casting globular structure?

    <p>It contributes to a semi-solid state</p> Signup and view all the answers

    Why is recycling important for aluminum alloys according to the text?

    <p>To reduce energy consumption during extraction</p> Signup and view all the answers

    Which statement accurately describes the processing methods of rheocasting and thixoforming?

    <p>Rheocasting uses existing alloys, while thixoforming requires specialized billets.</p> Signup and view all the answers

    Why are aluminium alloys considered relatively easy to process?

    <p>Having a comparatively low melting point</p> Signup and view all the answers

    Study Notes

    • Raw materials for glass production are melted at 1600°C.
    • Molten glass is homogenized and bubbles are removed.
    • The glass melt is then cooled to 1100°C to achieve the correct viscosity for the float bath process.
    • In the float bath process, glass flows over a smooth molten tin bath at around 500°C in a protective atmosphere of nitrogen and hydrogen.
    • The glass is annealed in a cooling tunnel to avoid residual stresses before being electronically inspected, cut into sheets, and packed for shipment.
    • Fusion forming, also known as the overflow and down-draw method, is used to produce flat glass sheets with high precision and uniform thickness.
    • Blow molding is utilized to manufacture glass containers like bottles and jars using compressed gas inside forming molds.
    • Dislocation glide is the mechanism responsible for the plastic deformation of crystalline materials, where shear stress allows dislocations to move through the crystal lattice.
    • Work hardening and annealing are processes used to control the mechanical properties of aluminum alloys, impacting their strength and yield stress.
    • Thermal and electrical conductivity of ceramics vary, with most ceramics being electrical insulators and having high to moderate thermal conductivity.
    • Technical ceramics offer high melting points, stiffness, low thermal expansion, hardness, wear resistance, and reasonable strength and fracture toughness.
    • Structural properties of materials, including stiffness, strength, hardness, ductility, fracture toughness, wear resistance, environmental resistance, thermal expansion, and thermal shock resistance, play crucial roles in material performance.
    • Stress-strain testing is conducted to measure material properties such as Young's modulus, which determines the material's stiffness and elastic behavior.
    • Lead glass, also known as lead crystal, contains lead oxide which enhances refractive index and light dispersal but has poor thermal shock resistance.
    • Bioglass is designed for medical applications to repair damaged bone tissue by promoting new bone growth through its water-soluble and bioactive composition.
    • Glass ceramics combine crystalline and amorphous phases for materials with net zero thermal expansion, achieved through controlled crystallization processes.

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