ME230 - L1 - Intro (1)-merged

Importance of Materials in Design

  • Historically significant in design; materials define limits of creation.

  • Today’s wide range of materials leads to more opportunities and challenges.

  • Examples:

    • Wright Biplane (1903): Made from spruce, muslin, balsa, steel wire, and silk.

    • Douglas DC3 (1935): Aluminum airframe for carrying more passengers and freight.

    • Boeing 787 (2010): 80% CFRP by volume for fuel efficiency and eco-friendliness.

Evolution of Plastics

  • Pre-1863: Use of natural materials like ivory in billiard balls.

  • Modern plastics lead to innovations like timed-release drug delivery, contact lenses, PPE, and LCD displays.

  • Health Concerns: Detection of microplastics in human tissues raises safety questions.

Why Study Materials Science and Engineering?

  • Key Themes:

    • Structures

    • Processing

    • Performance

  • Roles:

    • Mechanical engineers focus on desired performance;

    • Materials scientists analyze structure-property relationships;

    • Materials engineers apply knowledge to develop new materials with tailored properties.

Multi-Scale Structure of Materials

  • Physical Properties: Mechanical, electrical, magnetic, thermal, optical.

  • Subatomic Particles: Protons, neutrons, electrons, photons, phonons.

  • Key Structural Concepts: Atomic and crystal/molecular structures define material behavior.

Forging and Blacksmithing

  • Processes:

    1. Steel selection and additional materials.

    2. Forging, shaping, and folding of materials.

    3. Annealing to reduce brittleness.

    4. Final detailing through sharpening.

    5. Heat treatment techniques for hardening (quenching and tempering).

Case Study: Mythbusters

  • Katana Comparison:

    • Hand-forged katana vs stainless steel katana.

  • Technique insights found from documentaries and practical explorations into forging methods.

Review of ME115 Material Science Concepts

  • Topics include:

    • Binding energy;

    • Lattice, basis, unit cells, and crystal structure;

    • Importance of defects in materials;

    • Definitions of mechanical properties.

Crystal Structure Overview

  • Discusses 14 Bravais lattices categorized as cubic, tetragonal, orthorhombic, hexagonal, monoclinic, triclinic, and trigonal.

  • Each structure has specific geometric properties: dimensions and angles defined by parameters (a, b, c, α, β, γ).

Common Crystal Structures for Metals

  • Notable types: Body-Centered Cubic (BCC), Face-Centered Cubic (FCC), Hexagonal Close Packed (HCP).

Defects in Materials

  • Types of defects:

    • Point defects include vacancies and self-interstitials.

    • Line defects (dislocations);

    • Area defects involve grain boundaries;

    • Volume defects include precipitates and voids.

Strength vs. Defects

  • Discusses theoretical strengths of metals versus measured strengths, emphasizing the critical impact of defects in real-world materials.

Focus on Dislocations

  • Yield strength relates to the material's ability to undergo plastic deformation, heavily influenced by dislocation movement.

Applications: Electrochemical Corrosion

  • Key chapters from Askeland focusing on various forms of electrochemical corrosion and protective measures.

  • Importance of balancing anodic and cathodic reactions to mitigate corrosion risk.

Corrosion and Degradation Mechanics

  • Corrosion: A result of environmental interactions leading to property deterioration, often involving dissolution or scale formation.

  • Degradation: Pertains primarily to polymers and their interactions with the environment.

Mechanisms for Corrosion

a. Requirements for Corrosion:

  1. Dissimilar electro-potential materials.

  2. Physical electrical contact between materials.

  3. Presence of an electrolyte.

  • Importance of removing one or more of these factors to prevent corrosion.

Addressing Localized Corrosion

  • Localized forms include intergranular corrosion and concentration cells leading to preferential grain boundary attacks.

Preventive Strategies for Corrosion

  • Recommendations include proper material selection, design considerations to minimize crevice formation, and methods for applying coatings and inhibitors.

Galvanization & Cathodic Protection

  • Techniques such as using sacrificial anodes or applying an external potential to mitigate corrosion risks.

Polymer Degradation Insights

  • Mechanisms:

    • Swelling from absorption;

    • Chemical reactions leading to scission of molecular chains.

The Materials Life Cycle

  • Concepts related to life cycle analysis (LCA) and embodied energy help assess environmental impacts of material use.

  • Recyclability vs. Biodegradability: Criteria defining how materials can be reprocessed or decomposed.

Recycling Processes

  • Processes categorized into open-loop and closed-loop recycling methods, detailing material handling post-use.

Challenges with Metal Recycling

  • Specific composition ranges of metals pose challenges for quality assurance in recycling processes.

Example Applications of Ferrous Alloys

  • Various strength categories and their respective uses in industries outlined.

Understanding Eco-Audit Tools

  • Overview of Granta’s LCA tools focusing on energy costs associated with material production and processing.

Strengthening Mechanisms for Materials

  • Techniques such as strain hardening, solid solution, and grain boundary strengthening help improve material properties.

Heat Treatment Fundamentals

  • Processes including quenching, annealing, and aging (precipitation hardening) play critical roles in material modification.

Recrystallization Processes

  • Describes stages of recrystallization from nucleation to complete transformation, impacting microstructure and mechanical properties.

Phase Equilibria and Diagrams

  • Fundamentals of phase diagrams including basic terminology (systems, phases, components) and Gibb’s phase rule.

Understanding Atomic and Molecular Interactions

  • Critical to the study of condensed matter, highlighting the importance of atomic arrangements in phase transitions.

Advanced Diffusion Concepts

  • Physical mechanisms affecting diffusion rates in various materials emphasizing substitutional vs. interstitial diffusion.

Steady State vs. Non-Steady State Diffusion

  • Key principles governing diffusion processes; the mathematical representation through Fick's laws.

Creep and Diffusion Relationships

  • Examines how diffusion processes relate to material behavior under long-term stress and temperature exposure.