THE HISTORY AND EVOLUTION OF MATERIALS
Early human history is divided into eras named after
the materials that were predominantly used at that time. The stone age,
copper age, bronze age and iron age suggest how important these
materials were in the development of early technology.
Early humans could only utilize the materials that
they found to hand. Stone, reeds, wood, clay, animal hides, hair and
bone enabled them to survive in otherwise inhospitable conditions.
During these earliest periods organic materials were
by far the most important.
Human resources were greatly enhanced by the
discovery that mixing and heating materials, often change their
characteristics. Ceramics (the earliest inorganic material to be used
and worked) are good examples. A pliable clay can be moulded into the
required shape and heated to create a much harder and tougher material,
because the micro-structure of the clay changes during the
"firing" process.
From about 8000BC humans in what is now known as the
middle-east, crafted locally found gold and copper to make decorative
items.
By about 4000BC they had learned how to smelt copper
from ore. Around 2000BC it was found that another soft metal - tin -
could be added to copper to produce an alloy which possessed some of the
features of both parent metals. This alloy was an attractive gold
coloured metal, that was much harder than either copper or tin. This led
to the beginning of the bronze age.
The extraction of iron from heamatite (iron ore)
began about 1200BC. In its pure form iron is inferior to bronze in
almost every way, but people found that by heating iron in charcoal and
hammering it into shape produced a much tougher metal - steel.
They also found that by plunging the heated metal
into cold water (quenching) they were able to produce a very hard but
brittle steel (hardening). They soon learned that these properties could
be modified by reheating and cooling more slowly (tempering) so that
most of the initial hardness was retained whilst at the same time making
it much tougher and less brittle.
Although naturally occurring polymers such as bitumen
shellac and rosin have been used since 2000BC it was not until 1862 that
the first manufactured plastic called parkesine was developed. In 1906 a
chemist called Baekeland produced the first synthetic polymer Bakelite.
Since then many new plastics with different colours and properties have
been developed.
In the last 100 years our knowledge and understanding
of materials has grown considerably. Today our use of traditional
materials are constantly being improved and new materials are being
synthesized.
We now have glass which is stronger than steel,
Ceramics which remain tough and rigid even when white hot and optical
fbres which can transmit information at the speed of light.
There are a
large number of materials available to product designers today, and
they can be supplied in many different forms. New and improved materials
are being developed all the time.
A product designer needs to know what materials are
available, how they behave in use and how they can be worked or
processed during manufacture and construction. Having a good
understanding of these things will help you to select suitable materials
for your product designs.
Everyone involved with designing or improving
products must have sufficient knowledge of materials to be able to
select, process and finish the materials that best fit the purpose for
which the product is designed.
In choosing materials for a particular project or application you
will need to consider their physical and working properties. So that you
are able to decide which material is best and which methods of
processing and finishing are required in order turn raw materials into
finished products.
One way of obtaining this information is to use books
and other written resources, but unless their is a focus to your
research this can be rather laborious. A good starting point is to
examine a range of existing products in order to establish how other
designers have solved similar these problems.
This procedure is often called product analysis.
Product analysis involves analysing an existing product in order to
identify the materials that have been used, the properties that make
them suitable for the task for which they were designed as well as an
awareness of the processes used in their manufacture, construction and
assembly.
As with most decisions, choosing materials requires
you to weigh up a number of conflicting options. There are essentially
four factors which will influence your choice. These are:
This section of the Web is designed to
provide you with some of the background information to help you make these
choices.
SOME MATERIALS and their PROPERTIES
Solid materials can be divide into four main groups:
