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.
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- - PowerPoint PPT Presentation
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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.
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.