A WORLD OF MATERIALS We can see the work of materials engineers all around us Many industries rely on the expertise of materials engineers Civil engineers couldn’t design buildings aviation engineers couldn’t build aircraft and electronics engineers couldn’t make smartphones if it weren’t for materials engineers designing and testing the materials that go into each and every product Making things Every object we use is made of at least one material That’s what a material is something from which a thing can be made Materials in their natural state from which useful products are made are called raw materials Some raw materials just have to be shaped to make them useful such as stone for a building and wood to make furniture But most materials have had to be altered in some way Metals plastics and fabrics are all materials that have been processed from raw materials Metals are extracted from rock ores plastics are made from chemicals found in petroleum and fabrics have to be woven from natural and human-made materials Strength is an important characteristic of the materials we choose for building 4
Engineering the future Engineers are always looking for ways to improve materials Better materials make new technologies possible One of the most exciting things about materials engineering today is our growing ability to understand how materials are put together right down to the invisible level of atoms Materials scientists and engineers are focusing their efforts on changing the properties of materials by controlling their structure With this knowledge materials engineers hope to design new materials suited to perform any task Making the right choice So how do engineers know which materials are best for each job First they have to understand the properties of each material the qualities each one has that make it suitable for a particular use Materials and their properties affect every aspect of the things we use For example they affect cost reliability and how environmentally friendly they are Engineers generally follow an eight-step process when they are trying to design a solution to a problem Like all engineers materials engineers may not follow this process exactly but it generally guides their work Materials engineering researchers are always experimenting with new materials Steps in the design process Define the problem Identify criteria and constraints Brainstorm ideas Select a solution Build a model Improve the design Test the model Communicate the solution 5
MATTER AND MATERIALS All of the materials we make use of and in fact everything around us is made of matter The air we breathe the food we eat the clothes we wear the ground we walk on and we ourselves are all made of matter Matter is made up of tiny particles called atoms There are 94 different kinds of atom that exist in nature and more have been created in the laboratory A substance that is made up of just one kind of atom is called an element Learning about chemistry is an important part of a materials engineer’s training 6 Molecules and compounds Elements can join together in different ways to form larger particles called molecules A molecule made of two or more different elements is called a compound Most of the materials we come across in everyday life are made up of compounds The elements can be combined to make an immense variety of compounds each with different properties and uses Compounds are formed by chemical reactions Newly formed compounds can have quite different properties from the original chemicals that reacted together The chemical properties of a material tell you how it will behave when you do different things to it They also tell you how it will react with other elements or compounds and what new materials can be made from it All of this is important knowledge for the materials engineer
THE PERIODIC TABLE All chemicals have different properties and it is important that engineers understand them The periodic table of the elements devised by Dmitri Mendeleev in 1864 identifies and organizes the chemical elements by their properties In 2006 materials engineers voted the periodic table as the most indispensable reference tool for materials scientists and engineers In the periodic table the elements are arranged into groups depending on their properties and atomic structure Physical properties As well as understanding how materials behave chemically materials engineers also have to be aware of how they can change physically For example they need to know how a material will react to changes in temperature How much will it expand when heated Is it soluble in water and likely to dissolve if it gets wet Is it brittle and likely to break easily like glass Could it become brittle if it gets too cold If materials engineers get things wrong it can sometimes have tragic consequences For example the space shuttle Challenger and its crew were lost in 1986 because seals on the rocket boosters failed to work properly at low temperatures Thankfully almost all of the space shuttle missions were safe and successful 7
