New DM308 Materials

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Questions and Answers

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?

Produces flatter and more uniform thickness glass sheets Signup and view all the answers

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

Burgers vector Signup and view all the answers

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

Edge dislocation Signup and view all the answers

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

Dislocation glide Signup and view all the answers

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

Critical resolved shear stress (CRSS) Signup and view all the answers

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

{111}-type planes Signup and view all the answers

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

4 Signup and view all the answers

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

{111}-type directions Signup and view all the answers

Why are FCC crystals considered comparatively plastic?

Due to high number of slip systems Signup and view all the answers

What type of strengthening does Zinc provide in Aluminum alloys?

Solution strengthening Signup and view all the answers

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

Strength and hardness Signup and view all the answers

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

Nucleation sites of recrystallized grains Signup and view all the answers

How does cryogenic deformation affect the strength of aluminum alloys?

Increases strength at the expense of ductility Signup and view all the answers

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

Substantially increases it Signup and view all the answers

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

Magnesium (Mg) Signup and view all the answers

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

Cellular structure formation Signup and view all the answers

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

Cold rolling Signup and view all the answers

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

Plasma spraying Signup and view all the answers

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

High stiffness Signup and view all the answers

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

Considerably harder with excellent wear resistance Signup and view all the answers

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

Lower density Signup and view all the answers

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

Ceramics Signup and view all the answers

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

Low density Signup and view all the answers

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

They act as stress concentrators. Signup and view all the answers

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

By heat treatment and alloying. Signup and view all the answers

Why are grain boundaries considered good sites for precipitate formation?

Since they provide faster solute diffusion and nucleation sites. 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?

Allows a coarser but more uniform precipitate distribution. Signup and view all the answers

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

By forming a barrier against further corrosion. Signup and view all the answers

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

It acts as a sacrificial anode and corrodes rapidly. Signup and view all the answers

What property is not covered in this course?

Conductivity Signup and view all the answers

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

Force is directly proportional to extension Signup and view all the answers

In tension, the strain in a material is:

Always positive Signup and view all the answers

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

Hydraulically actuated Signup and view all the answers

What is the main difference between tensile and compressive stresses?

Tensile stresses are positive; compressive stresses are negative Signup and view all the answers

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

Force constant k Signup and view all the answers

Positive strain occurs in which situation?

Tension Signup and view all the answers

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

Ensures cohesion of the ceramic powder in the green parts Signup and view all the answers

What is a characteristic property of lead glass?

Absorption of radiation Signup and view all the answers

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

Dispersing Signup and view all the answers

Which application is NOT associated with the use of Bioglass?

Solar heat collectors Signup and view all the answers

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

Binder removal Signup and view all the answers

What sets glass ceramics apart from traditional glasses?

Controlled crystallization Signup and view all the answers

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

Lower the melt viscosity Signup and view all the answers

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

Reduces viscosity of the mixture Signup and view all the answers

Why are bioglasses formulated to be chemically similar to hydroxyapatite?

To enhance mineral growth in bones Signup and view all the answers

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

Machining ceramics in their unfired state Signup and view all the answers

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

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

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

Contributes to net zero thermal expansion Signup and view all the answers

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

Finishing Signup and view all the answers

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

Negative thermal expansion coefficient Signup and view all the answers

How does bioglass promote the growth of new bone tissue?

"Stimulates formation of hydroxyapatite" Signup and view all the answers

What is the purpose of plasticising in technical ceramics processing?

Enhancing the plasticity of ceramic mixtures Signup and view all the answers

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

Forming/shaping Signup and view all the answers

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

Creating refractories and crucibles Signup and view all the answers

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

3000 BCE Signup and view all the answers

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

Luxury material 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?

Obsidian Signup and view all the answers

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

Middle Ages Signup and view all the answers

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

Obsidian Signup and view all the answers

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

The primary intermetallic phases present Signup and view all the answers

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

2017 Signup and view all the answers

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

Creep resistance Signup and view all the answers

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

6xxx Signup and view all the answers

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

Correlated with magnesium and silicon content Signup and view all the answers

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

Excellent corrosion resistance Signup and view all the answers

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

Replaced by newer derivative systems with higher strength 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?

3.5 Signup and view all the answers

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

Borosilicate glass Signup and view all the answers

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

Vitrification process Signup and view all the answers

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

Increases thermal conductivity Signup and view all the answers

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

Lead glass Signup and view all the answers

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

High thermal conductivity Signup and view all the answers

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

Borosilicate ceramic Signup and view all the answers

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

To create a water-soluble formulation Signup and view all the answers

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

High thermal expansion coefficient Signup and view all the answers

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

To reduce the porosity of products Signup and view all the answers

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

The slip becomes more viscous Signup and view all the answers

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

To adjust the height of the ceramic tape Signup and view all the answers

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

Slip casting Signup and view all the answers

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

Enables a high degree of precision and complex geometries Signup and view all the answers

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

Gel-like material Signup and view all the answers

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

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

What was the significance of glass during the middle ages?

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

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

Incidental production during metal-working processes. Signup and view all the answers

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

By using glass extensively in architecture and interior design. Signup and view all the answers

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

Advancement of modern plate glass technologies. Signup and view all the answers

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

Lightning strike Signup and view all the answers

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

Knapping Signup and view all the answers

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

Because of the high production costs involved. Signup and view all the answers

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

Reducing forming strain rates Signup and view all the answers

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

Impurities from recycled stock Signup and view all the answers

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

Increased use of castings in automotive industry Signup and view all the answers

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

Alloys prepared from recycled metals Signup and view all the answers

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

1:2 Signup and view all the answers

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

Impurity levels Signup and view all the answers

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

Transmissions casings Signup and view all the answers

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

To grow the desired distribution of g’ precipitates Signup and view all the answers

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

Secondary Grains Signup and view all the answers

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

Effusion cooling Signup and view all the answers

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

For heat treatment to optimize microstructure Signup and view all the answers

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

Freckles Signup and view all the answers

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

Machine blade to shape and perform NDT Signup and view all the answers

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

Reducing porosity of products Signup and view all the answers

What distinguishes tape casting from slip casting in ceramic production?

Tape casting produces thin ceramic tapes or sheets Signup and view all the answers

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

Sol-gel processing Signup and view all the answers

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

Ceramic particles are suspended in water Signup and view all the answers

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

Adjusting the thickness of the ceramic tape Signup and view all the answers

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

Polymerization reaction Signup and view all the answers

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

By allowing drying to a 'leather dry' state Signup and view all the answers

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

Gel-casting Signup and view all the answers

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

Water solubility Signup and view all the answers

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

Additional lead oxide Signup and view all the answers

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

Production of materials with net zero thermal expansion Signup and view all the answers

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

Negative thermal expansion coefficient Signup and view all the answers

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

Optics Signup and view all the answers

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

Lead glass Signup and view all the answers

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

Glass ceramics have negative thermal expansion coefficient Signup and view all the answers

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

$CaO$ 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?

Precipitation hardening Signup and view all the answers

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

They hinder atomic diffusion Signup and view all the answers

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

Orowan bowing Signup and view all the answers

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

APB energy Signup and view all the answers

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

Grain boundaries Signup and view all the answers

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

It represents dislocation magnitude and direction Signup and view all the answers

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

They act as obstacles Signup and view all the answers

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

Precipitate pinning 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?

Lecture 4 Properties and processing of ceramics Signup and view all the answers

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

Engineering materials - Ashby and Jones Signup and view all the answers

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

Glass materials Signup and view all the answers

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

Superalloys Signup and view all the answers

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

High temperature resistance Signup and view all the answers

What distinguishes light alloys from high-temperature alloys?

Heat resistance Signup and view all the answers

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

Sintering Signup and view all the answers

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

Cubic boron nitride (c-BN) Signup and view all the answers

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

High-temperature structural parts Signup and view all the answers

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

Flammability in air Signup and view all the answers

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

High-temperature lubricants Signup and view all the answers

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

Silicon Nitride (Si3N4) Signup and view all the answers

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

Second-highest hardness after diamond Signup and view all the answers

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

Moderate properties at a moderate cost Signup and view all the answers

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

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

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

Thixotropic Signup and view all the answers

What is the difference between rheocasting and thixoforming?

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

What is a characteristic of aluminium casting globular structure?

It contributes to a semi-solid state Signup and view all the answers

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

To reduce energy consumption during extraction Signup and view all the answers

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

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

Why are aluminium alloys considered relatively easy to process?

Having a comparatively low melting point 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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Description

Learn about the three possible types of dislocations: edge, screw, and mixed dislocations, which are described by their Burgers vector. Explore how dislocations can move through a crystal via dislocation glide, involving the breaking and re-forming of inter-atomic bonds.