Effects of Toxic Materials

Narcotic Effects-Result from the inhalation of toxic substances. Effects include instability or drowsiness or loss of consciousness or in serious cases death.

Systemic Effects-Result in the fundamental organs (heart, brain, liver & kidneys) being attacked. The effects are irreversible.

Irritants-1. Contact with mineral oils can cause skin cancer.2. Frequent contact with water based emulsions can cause dermatitis.3. Continual contact with cutting fluids can cause the skin to become swollen.

Fatigue & Creep

Fatigue-A component may fail when subjected to a stress well below it’s yield point if it has been subjected to repeated loading and unloading (cycle stressing) at a lower stress. Failure of a component in this manner is known as fatigue failure.

Creep-Factors that effect creep behaviour of metals include the temperature and the nature of the load on the metal.

Examples of Failures

Corrosion

How to minimise corrosion –1. Avoid having dis-similar metals in contact with each other.2. Design the component so that moisture isn’t allowed to collect on it’s surface.3. Protect surfaces with a treatment. (eg painting, galvanising, dip coating)

Sacrificial Protection (anodic/cathodic protection) –Zinc is a good choice to protect steel from corrosion because it is anodic to steel. This means that if there is zinc (anode) in the vicinity of mild steel (cathode) the zinc will corrode not the steel.

Corrosion

Cathodic Protection• Sacrificial Protection (anodic/cathodic

protection) –Zinc is a good choice to protect steel from corrosion because it is anodic to steel. This means that if there is zinc (anode) in the vicinity of mild steel (cathode) the zinc will corrode not the steel.

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Adhesives

Joining using adhesives –1. Surfaces clean and degreased.2. The joint should be designed so that peel force are minimised.3. Adhesive are best under tensile. Compression or shear forces.

Safety –Adhesives are hazardous due to their narcotic effects.

Ore Dressing

This means seperating metals from their ores.

Properties which facilitate ore dressing: Mass, Density. Electrostatic & Magnetic.

Methods1. Gravity Concentration- this is used to separate rocks from ores by shaking and the heavier particles fall to the bottom.2. Floation-chemical agents are added to the liquified ore and these cause the mineral to float to the top, where it is collected. 3. Magnetic Seperation-the ore is passed over a drum inside which there is a magnet which is stationery. The magnetic material will be carried on further than the non-magnetic and therefore will be seperated.

Hydrometallurgy- uses aqueous solutions called leaches to serperate metals from their ores.

Pyrometalurgy-is based on the use of heat energy by means of a furnace as in smelting the ore.

Magnetic Seperation

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Covalent BondThis means the

atoms share electrons.

Water H2O

Ionic BondWhen an atom gives

away an electron it becomes positive, then it has a charge so it’s called an Ion.

Salt = Na+ & Cl-

Metallic Bonds

Clouds of free electrons hold the atoms together.

It’s these free electrons that allow metals to conduct heat and electricity.

Defects in Metal Crystals

A Line Defect (dislocation)An incomplete line of atoms in the crystal structure.

A Vacency.(point defect)A missing atom in the crystal structure.

Crystalline/Amorphous

Crystalline

Regular, repeated patterns

Amorphous

Erratic, unrepetitive arrangements.

Disposal of waste plastics

Recycling

Incerination (burning)

Landfill (dumping)

Age Hardening

This means that some alloys of aluminium increase in hardness and strength over a period of a few days when they have been quenched from high temperatures.

Allotropic or polymorpic

This is where materials can exist in two states for example iron is FCC above 183ºC and BCC below this temperature.

Carbon, Diamond & Graphite are the same materials in different physical forms.

Carbon Diamond Graphite

Slip

Slip

This occurs more easily in FCC materials because the atoms are packed closer together. This enables one plane of atoms to slide over another easily.

Dendritic Growth

This is used to describe how metals solidify as they grow in a tree like structure.

Factor of Safety

This means that a component is designed to carry a load much greater than that it will ever have to carry in use.

Abbreviations CD-ROM Compact Disk-Read Only

Memory

ISP Internet Service Provider

DOS Digital Operating System.

RAM Random Access Memory

ROM Read Only Memory

CPU Central Processing Unit

IC Integrated Circuit

PTFE Polytetrafluoroethylene

VDU Visual Display Unit

LCD Liquid Crystal Display

LDR Light Dependant Resistor

CAD Computer Aided Design

PCB Printed Circuit Board

HSS High Speed Steel

DPDT Double Pole Double Throw

PLC Programmable Logic Controller

ALU Arithmetic Logic Unit

CD-RW A CD onto which information may be saved on

E-Mail Electronic-Mail, a method of sending data from one computer to another. Through the phone lines or wireless.

uPVC unplasticised Polyvinylchloride. Used in guttering

LED Light Emitting Diode

LAN Local Area Network – Internet

http Hypertext Transfer Protocol

DVD Digital Versatile Disc

SPST Switch Single pole single throw

H.S.S High speed steel.

Contribution to Technology 1997-2012Questions Henry Maudslay-Eng-

Screwcutting Lathe-1800. Simon Stevins-Flemish-Decimal

System-1548 to1620. Michael Farady-Eng-

Electromagnetic Induction-1791to1867.

Gustaf Dahlen – Swed. “sun valve”Switch off light houses by day

Willhelm Roentgen- Ger. 1895X-Rays

German Sommeiller-Compressed air Drill.

Jack Kirby- US 1958Integrated Circuit

Chester Carlson US Photocopier

Theodore Maiman-US-Laser-1960

Charles Parsons-Ire-Steam Turbine-1884.

Eli Whitney-Cotton Gin Mass Prod.-1798.

Gottlieb Daimler-Ger-Motor Car Engine-1885.

Daniel Bernoulli- SwissFluid Dynamicss

Robert Boyle-Ire-Gas, Pressure & Volume-1662.

Blaise Pascal- Fr. Calculator, Fluids

Dugald Clerk-Scot-Two Stroke Engine-1878.

Leo Bakeland-Belg-Bakelite-1909 Joseph Henry- US –

Electromagnet Christopher Cockerell 1956

Hovercraft

Contributions to Technology

Ivan Sikorsky- Russian Helicopter

Dr Von karman & General H Arnold-Wind Tunnel.

Charles Babbage-Eng-Computer-1823

W Shockley, J. Bardeen & W Brattin-US-Transistor-1948

Victor Popp- First Pneumatic Network

JP Holland (Ire) 1898 Submarine

Viktor Kaplan – Austrian 1913 Turbine

Others John T Parsons-Punch cards

for tool movement. Thomas Seeback-Thermo-

Electric Couple. Jean-Louis Poiseville-U tube

Pressure Gauge. Thomas Newcomen-Eng-

Steam Engine-1712. Richard Muller-Microchip William Stanley-

Transformer

Louis Bonneville-Transmission System

Charles Parsons-Ire-Steam Turbine-1884.

2013(i) Nicolaus Otto The German inventor of the first internal-combustion engine to efficiently

burn fuel directly in a piston chamber.

(ii) Frank Whittle This British engineer patented the basic design for the turbojet engine in

1930. The principles of his jet engine were used in British, German and American aircraft during World War II.

(iii) Dugald Clerk Scottish engineer who designed the world's first successful two-stroke engine in 1878 and patented it in England in 1881.