Material Bonding and Properties

• A material refers to something tangible that constitutes a physical object.
• Material science explores the relationships between the structures and properties of materials to understand how they behave and why.
• Material engineering involves adapting and modifying existing materials to meet societal needs.
• Material engineering also involves creating new combinations of elements to produce materials with desirable properties.
• There are no entirely "new" materials, just novel combinations of existing ones.
• At the heart of every engineering endeavor lies a materials problem.
• Human activities and progress are intertwined with creating things that aid Activities of Daily Living (ADL).
• Christian Jurgensen Thomsen categorized materials technology into the Stone, Bronze, and Iron Ages.
• These ages are defined by advancements in materials, not specific time periods.

Stone Age

• The Stone Age is the longest of the material ages.
• Materials used included stone, clay, wood, hair, fur, animal skins, bone, and sinews.
• The Stone Age materials were used not only for beauty but also for function.

Bronze Age

• Bronze is an alloy, consisting of two or more elements.
• Bronze offered superior properties compared to available materials.
• Bronze offers superior engineering properties.
• Bronze is shaped by hammering or casting.
• Bronze is easier to shape than stone.
• The hardness of bronze can be controlled by adjusting its chemical composition, i.e., alloying.
• Bronze is corrosion resistant.
• Thomas Jefferson said, "Those who hammer their swords into plows will plow for those who do not."
• Bronze is still used today in bushings and bearing material, marine hardware, coins and medals, sculpture, and household hardware.

Iron Age

• Iron is harder and tougher than bronze.
• Hardness is a crucial metric in materials engineering.
• Iron offers greater cutting efficacy and lasts longer.
• Hardness is measured using the Rockwell Hardness Testing standard.
• Toughness means having the energy to resist fracture.
• Bronze remained in use where it excelled, while iron replaced it in other applications.

Mixed Materials Use

• Materials are used to optimize function.
• Ductility is a common material property.
• Corrosion resistance.
• Iron weapons are cost-effective.
• Carbon steel is processed by smelting.

Metals and Society

• Metals include ductile, economical, conductive, and engineerable materials.
• The composition of metals can be processed.
• Structural steel is utilized in bridges, buildings, transportation, consumer goods, and defense.

Ceramics

• Useful in engineering industry.
• Beneficial for surgical use.
• Ceramics consists of multiple combinations of metals and non-metals.
• Ceramics are not limited to one metal plus one non-metal.

Benefits of Ceramics

• Chemical stability.
• High melting point.
• Aesthetics.
• Hardness.
• Non-Conducting.

Disadvantages of Ceramics

• Brittleness.
• Remedy is to add alloying elements or change processing.
• Tradeoffs: Toughness gained for hardness lost and vice versa.
• FAST, or Field Assisted Sintering Technique.
• Transparent ceramics.

Material Composition and Processing

• Metals and ceramics are highly ordered on an atomic scale.
• Atoms are arranged in regular patterns, which are known as crystalline structures.
• Glass has a non-crystalline structure.

Impurities in Materials

• Not necessarily bad.

Impurities in Ceramics

• Impurities can be naturally occurring.
• Gemstones, such as ruby, sapphire, and diamond, owe their existence to impurities.

Polymers

• Alternative to metals that is lightweight, ductile, and low-cost.
• Lower strength and melting point vs metals.
• Greater chemical reactivity.
• Examples are Kevlar, and Nylon (thermoplastic polymer)
• Silk.
• Polyethylene is where the structure of mers is key to properties of this polymer.

Molecular Weight

• Multiple Forms
• Molecular weight plays a crucial role in determining polymer properties.
• Empirical discipline.
• Composites are materials consisting of two or more materials.
• Composites have different physical and chemical properties.

Materials Age

• Materials from polymers, silicon, composite materials, super alloys, nanomaterials.
• Material strength to density ratio refers to a materials engineering mindset.

Materials Engineering

• Think: Composition, Structure, and Processing.
• The above dimensions provide desired engineering properties and enable practical application.
• Dimensional scales includes subatomic, atomic, microscopic and macroscopic levels.
• Relevant structure, properties, processing and performance.
• Wear of Total Joint Polyethylene poses a MAJOR material problem.
• Small wear particle disease.
• Particles can cause aseptic loosening of implants.
• Consequences of wear include pain, disability, surgery, and cost.
• Atomic Bonding.

Fundamentals

• Testing involving open air and underground elements is not allowed.
• Computer modeling of nuclear reactions is only permitted.
• Bonding is at the heart of material engineering and about an understanding of the scientific basis of bonding.
• Description of macro level material properties is merely phenomenological and not based on sound engineering.

Design Strategies

• Identify endpoints and start from fundamentals.
• Bonding is a major determinant of the engineering material type and properties.
• Chemical Bonding.

Biomedical Engineering

• Biological design cell fundamentals, and Materials design material fundamentals.
• Major source of cohesion in engineering materials because its involves the transfer or sharing of electrons.
• Weaker attraction because there is no sharing or transfer of electrons.
• Secondary occurs by events happening to the outer orbital (valence)electrons when one atom comes into the vicinity of another atom.
• To get desired properties and serve a specific role.
• BONE is the oldest known composite.

Examples of Materials and Composites

• Biological component: organized collagen
• inorganic component: imperfect mineral
• plywood: layers of alternating woods
• fiberglass: fibers in glass matrix
• auto glass: polymer between tempered glass layers
• reinforced concrete: steel rebar + concrete
• concrete = cement + aggregate + stone

Prior societies

• Societies relied different materials like: stone bronze, and iron
• Revision arthroplasty never preforms well as the primary arthroplasty (worse patient outcomes) Components showed → worn, malformed acetabular cups, delaminated pitted

Present Materials Advances

• Smart materials shape memory alloys or self-healing materials.
• Nanomaterials targeted drug delivery.

Key Summaries

• At the core of every engineering problem is a materials problem.
• Materials structure is determined by composition and processing.
• Material composition and processing determines properties.
• Material properties determine function and engineering application.
• Materials science and engineering occurs at all scale levels.
• Desing always involves material selection.
• Biomedical technology is critically dependent on material performance.
• Materials interact with biological systems (vice versa).

Heisenberg's Uncertainty Principle

Both particles and waves (dual nature)

• Particles which determines dot binding
• Waves which results position is probabilistic obtained by the Schrodinger equation Orbitals derived from the Schrodinger equation can provide different potential electron shapes Each with a unique shape with identified quantum numbers

Nuclear Details

• Mass of proton/neutron = 1.66 x 10-24 grams
• Mass of 1 Atomic Mass Unit (AMU)
• Reciprocal of AMU = Avogadro's number

Periodic Table

• Chemical identification occurs relative to nucleus
• Chemical bonding occurs relative to electrons and electron orbitals
• Ability of an atom to attract electrons to itself (how thirsty)
• Applies to covalent bonds

Bonding Integrity

• Material integrity governed by covalent bonding

Metallic Bonds

• Coordination numbers are typically high and determined by efficient packing considerations
• Luster
• Heat/Electrically conductive
• Ductile/Malleable/Strong

Electrons

• Involved with different ionization energy levels for electron atoms in the outer orbitals of metal atoms
• Lower energy state enables metallic/covalent outer shell energy states and can form by the exchange of valence electrons without asymmetrical dispersal

Quantum Mechanics of Metallic Bonding

• Weakers states with lower energies of delocalized electrons can be directional if bonding assumes a covalent nature

Dipole Moments

Charge separation

• Permanent/Instantaneous dipoles can be redistributed caused by more electrons in one energy region, and are weak due to low melting points.

Secondary Bonds

• Bonds from Vanderwaals dispersion, or induction

Chemical Bonding Summary

NOT always ideally separated involving bonds between molecules of composites which have stronger material properties and bonding

Explores electrical and thermal conductivity in materials due to electron delocalization. Discusses 'open' structures in covalently bonded materials and the mechanism behind Van der Waals bonds. Examines material properties, design considerations, and engineering applications.