Solution manual for exercises
Contents
Solutions for: Page
Chapter 1 2
Chapter 2 4
Chapter 3 14
Chapter 4 18
Chapter 5 22
Chapter 6 26
Chapter 7 38
Chapter 8 42
Chapter 9 52
Chapter 10 62
Chapter 11 75
Chapter 12 77
Chapter 13 86
Chapter 14 89
This booklet contains worked solutions for the end-of-chapter exercises in the
nd
2 edition of
Materials and the Environment
Eco text: solution manual 0 MFA, 29/08/2013
, Chapter 1
E 1.1. Use Google to research the history and uses of one of the following materials
Tin
Glass
Cement
Bakelite
Titanium
Carbon fiber
Present the result as a short report of about 100 - 200 words (roughly half a page). Imagine that you
are preparing it for school children. Who used it first? Why? What is exciting about the material? Do
we now depend on it or could we, with no loss of engineering performance of great increase in cost,
live without it?
Specimen answer: tin. Tin (symbol Sn), a silver-white metal, has a long history. It was traded in the
civilizations of the Mediterranean as early as 1500 BC (the Old Testament of the Christian bible
contains many references to it). Its importance at that time lay in its ability to harden copper to give
bronze (copper containing about 10% tin), the key material for weapons, tools and statuary of the
Bronze age (1500 BC – 500 BC). Today tin is still used to make bronze, for solders and as a corrosion
resistant coating on steel sheet (“tin plate” ) for food and drink containers – a “tinnie”, to an Australian,
is a can of beer. Plate glass is made by floating molten glass on a bed of liquid tin (the Pilkington
process). Thin deposits of tin compounds on glass give transparent, electrically conducting coatings
used for frost-free windshields and for panel lighting.
Most of the applications of tin could be filled by other materials – polymer coatings for food
containers, aluminum instead of tin to make bronzes, indium for transparent coatings (though at an
increased cost). Finding a replacement for tin in solders is more difficult.
E 1.2. There is international agreement that it is desirable (essential, in the view of some) to reduce
global energy consumption. Producing materials from ores and feedstocks requires energy (its
“embodied energy”). The table lists the energy per kg and the annual consumption of 4 materials of
engineering. If consumption of each could be reduced by 10%, which material offers the greatest
global energy saving? Which the least?
Material Embodied energy Annual global Annual energy
MJ/kg consumption (tonnes/yr) commitment (MJ)
Steels 29 1.1 x 109 3.2 x 1010
7
Aluminum alloys 200 3.2 x 10 6.4 x 109
Polyethylene 80 6.8 x 107 5.4 x 109
Concrete 1.2 1.5 x 1010 1.8 x 1010
3
Device-grade silicon Approximately 2000 5 x 10 1.0 x 107
Answer. An additional column has been added to the table above: it shows the annual energy
commitment associated with the production of each material (the product of the numbers in the two
columns to its left). Reducing consumption of steel and of concrete – by more efficient design of
structures perhaps – have by far the greatest potential for global energy saving. Doing the same for
device grade silicon has the least, by a large factor. Although the embodied energies of materials differ
considerably, it is the much greater differences in annual consumption that dominate the total energy
commitment and the carbon burden they generate. This is one reason that much of the discussion of
this book focuses on the materials used in the greatest quantities.
Eco text: solution manual 1 MFA, 29/08/2013