Materials Science Quiz

Introduction

• Agricultural machinery durability, service, and cost depend on the materials used in manufacturing process
• Machines made from substandard materials wear out quickly
• Heavy materials reduce power requirements and performance
• Engineers need knowledge of materials' physical properties, processing, and effective utilization to minimize waste and spoilage

Classifications

• Metals:
  • Ferrous: Iron and steel (cast iron, carbon steel, alloy steel)
  • Non-ferrous: Aluminum, copper, magnesium
• Non-Metals:
  • Inorganic: Glass, ceramics, plastics
  • Organic: Wood, rubber, leather, canvas

Manufacturing Metals

• Metal ores are extracted from the earth
• Iron is produced from iron ore (hematite/magnetite), while copper from copper ore and Aluminum from bauxite
• Blast furnaces combine iron ore, limestone, and coke at high temperatures (around 3000°C) to produce molten metal
• Molten metal is separated into ladles for cooling to form pig iron
• Pig iron is then melted and poured into molds to create iron, steel, and cast iron

Metal Characteristics

• Hard
• Easy to shape
• High melting temperature
• Low specific heat
• Good electrical conductivity
• Good thermal conductivity
• Ability to be deformed without fracture

Classifications of Metal

• Pure Metal: A single element, often too soft or lacking desired properties for commercial use
• Alloys: Mixtures of two or more metals, creating new metals with improved properties (like stainless steel, bronze)

Iron

• Pure iron (ferrite): A base material for iron and steel production
• Pig iron: Produced from hematite or magnetite ore by melting with limestone and coke
• Cast iron: Contains 1.7-6.7% carbon, low cost, good casting properties, high compressive strength and wearing resistance, but is brittle and has lower tensile strength.

Steel

• Molten steel is cast into an ingot and then shaped (rolled, forged, hammered, pressed)
• Structural steel (bars, cylinders, plates) are often used in machine frames
• Soft Centered Steel - durable to shock because the mild steel layer in the center is more deformable and has higher wear resistance than the hard steel at the outside. Usually used in moldboards and plough shares
• Low Carbon Steel: Carbon content below 0.25%, malleable, easy to cut and weld
• Medium Carbon Steel: Carbon content 0.25-0.50%, used in structural and machinery steel
• High Carbon Steel: Carbon content above 0.50%, used to make springs and tool steel
• Mild Steel (MS): Contains carbon from 0.15 to 0.25%, malleable, easy to cut and weld.
• Cold Rolled Steel (CRS): Medium carbon steel, used in machine parts needing strength and hardness (e.g., shafting).
• Stainless Steel (SS): Contains 1% Ni, 11-14% Cr, 0.6% Mn, 0.6% Si. Highly resistant to corrosion and oxidation, used in valves, nozzles, and dairy equipment.

Typical Properties of Iron and Steel

• A table showing the properties of various steels according to Carbon content (e.g. Tensile strength, percentage of elongation, Brinell's hardness).

Non-Ferrous

• Metals excluding iron; e.g., copper, aluminum, magnesium, and zinc

Aluminum Alloy

• Outstanding characteristics: high strength, light weight, excellent thermal and electrical conductivity, and resistance to corrosion.
• Y alloy: Strong casting alloy, used in cylinder heads and pistons.
• Silmin: Casting alloy for cylinder heads and crankcases
• Duralumin: Alloy with copper, magnesium, and manganese. Quenched at high temperatures and then aged to enhance strength and hardness.

Aluminum Production

• Description of the process using electrolytic and casting methods

Copper and Its Alloys

• High electrical and thermal conductivity, soft, good resistance to corrosion.
• Brass: (10-40% zinc alloy) used in radiators, pipes, screens, and instrument parts.
• Bronze: (5-20% tin alloy) used in bushings, springs, pipes, fittings, sprayers, and pumps.
• Kelmet alloy: (20-40% lead alloy) used in diesel engine bearings

Copper Production

• Steps of copper production from ore (crushing, grinding, concentration, smelting, and electrolytic refining)

Properties of Copper Alloy

• A table summarizing properties and usage of copper alloys (e.g., brass, bronze, Kelmet).

Metal Shapes

• Sheets: Rolled metal, thin, in various sizes (width, length, gauge)
• Strips: Thin, flat, less than 12 inches wide
• Plates: Thick metal, larger sizes (width, length, thickness)

Common Shapes of Metal Bars and Sheets

• Illustrations of various structural shapes (hexagon, octagon, I-beam, H-beam, reinforcing bar, etc)

Metal Bars

• Metal bars, available in various shapes and lengths (20ft or 6 meters)
• Used in different industries and applications

Structural Shapes

• The use of steel in structural components like angles, tees, and channels for agricultural machinery constructions
• Specifications specify quantity, type, and dimension of parts

Tubular Products

-Hollow metal shapes (e.g. pipes and tubes) in round, square, and rectangular.

• Specifications including shape, schedule, size and length

Common Structural Shapes of Bars

Illustrations of various common shapes of metal bars

Properties of Metal

• Physical properties: Characteristics of metals not influenced by external forces (color, density, weight, electrical and heat conductivity)
• Mechanical properties: Characteristics of metals responding to applied external forces (tensile strength, yield strength, ductility, hardness, brittleness, compressibility, malleability, toughness)
• Chemical properties: Characteristics regarding chemical reactions and compositions (resistance to corrosion)

Mechanical Properties of Metal

• Tensile strength: Maximum stress a material can withstand before breaking
• Yield strength: Stress at which a material begins to deform permanently
• Ductility: Ability to deform or stretch without breaking
• Hardness: Resistance to penetration or deformation
• Brittleness: Tendency to break under impact

Additional Mechanical Properties

• Compressive strength: Resistance to compression
• Malleability: Ability to be shaped and formed by hammering
• Toughness: Ability to withstand bending and twisting
• Grain size: Microscopic measurement of metal’s grain structure influencing resistance to deformation and breaking
• Machinability: Ease with which metals can be machined (cut, shaped)

Additional Properties of Metal

• Fusibility: Ability of metal to be melted and joined
• Strength: Resistance to deformation

Non-Metallic Materials

• Wood: Includes sapwood (moisture-carrying) and heartwood (hard core)
• Plastics: A large group of organic materials: molded shapes, light weight, resistant to moisture, low thermal conductivity, wide color range
• Rubber: Extracted naturally; excellent at withstanding deformation; recovers quickly upon release of the force; has many applications in engineering like sealing, shock control, and production of various components
• Ceramics: Include glass, ceramic oxides, glass ceramics, carbides, and nitrides (used in high-temperature applications or parts where extreme resistance to wear and tear is crucial)
• Fibers: Plant/animal sources for ropes, containers, felt, paper, and heavy cloth. Metal fibers, glass fiber, aramid fibers (engineered fibers)

Plastic Processing

• Description of how plastic pellets are transformed into various forms through mechanical processing

Polymer Processing

• Description of process to create polymers from raw materials

Examples

• List of examples of acrylic, epoxy, fluoroplastic, nylon, phenolic resins, etc.

Engineering Ceramics

• Diverse group of materials including glass, ceramic oxides, and other similar materials.

Fibers

• A class of engineering materials (natural or synthetic) including jute, flax, hemp, metal fibers, Aramid, and glass fibers commonly used for reinforcement, support, rope making, and miscellaneous purposes

Glass

• A non-crystalline, amorphous solid, most often made from silica, lime, and soda
• Various types of glass like soda-lime, borosilicate, etc., with differing properties