Transcript Effects of Toxic Materials

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.
2.
3.
Contact with mineral oils can cause skin cancer.
Frequent contact with water based emulsions can cause dermatitis.
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.
2.
3.
Avoid having dis-similar metals in contact with each other.
Design the component so that moisture isn’t allowed to collect on it’s
surface.
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.
 View Video clip on blog
Adhesives
 Joining using adhesives –
1.
2.
3.
Surfaces clean and degreased.
The joint should be designed so that peel force are minimised.
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.
 Methods
1.
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
 View Video clip on blog
Covalent Bond
 This means the atoms
share electrons.
 Water
H2O
Ionic Bond
 When 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
 Amorphous
Regular, repeated patterns
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

PLC Programmable Logic Controller

ALU Arithmetic Logic Unit

CD-RW A CD onto which information
may be saved on


ISP
Internet Service Provider

DOS
Digital Operating System.

RAM
Random Access Memory

ROM
Read Only Memory

CPU
Central Processing Unit
E-Mail Electronic-Mail, a method of
sending data from one computer to
another. Through the phone lines or
wireless.

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
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. 1895
X-Rays
 German Sommeiller-Compressed air
Drill.
 Jack Kirby- US 1958
Integrated Circuit
 Chester Carlson US Photocopier
 Theodore Maiman-US-Laser-1960
 Charles Parsons-Ire-Steam Turbine1884.
 Eli Whitney-Cotton Gin Mass Prod.1798.
 Gottlieb Daimler-Ger-Motor Car
Engine-1885.
 Daniel Bernoulli- Swiss
Fluid 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-Computer1823
 W Shockley, J. Bardeen & W
Brattin-US-Transistor-1948
 Victor Popp- First Pneumatic
Network
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
 JP Holland (Ire) 1898 Submarine
 Viktor Kaplan – Austrian
1913 Turbine
 Louis Bonneville-Transmission
System
 Charles Parsons-Ire-Steam Turbine1884.
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.