Ceramics – introduction
The term ‘ceramic’ comes from the Greek word meaning ‘pottery’ – these clay-based domestic wares, art objects and building products are familiar to us all – but pottery is just one part of the ceramic world.
Traditional ceramics.
Traditional ceramics are clay–based. The categories of pottery shown here are earthenware, stoneware and porcelain. The composition of the clays used, type of additives and firing temperatures determine the nature of the end product.
There is an increasing demand in our modern world to develop new materials with properties that fit certain requirements. As a result, a branch of science/engineering known as ‘materials science’ has evolved. It investigates the relationship between the structure of materials at the atomic or molecular level and their physical properties at the macroscopic level.
Ceramics is one of the areas of interest to a materials scientist and is the oldest branch of materials science. A ceramic is a non-metallic solid made up of either metal or non-metal compounds that have been heated and cooled. In general, they are hard, corrosion-resistant and brittle. ‘Ceramic’ comes from the Greek word meaning 'pottery’ – these clay-based domestic wares, art objects and building products are familiar to us all – but pottery is just one part of the ceramic world. Ceramics now includes advanced ceramics used in engineering and medicine.
Silicon nitride ball bearings
Many skateboarders choose silicon nitride ball bearings (inset) for smooth, low-friction wheel characteristics. Silicon nitride is a hard, tough ceramic with excellent wear resistance.
Skateboarder photo ChrisGoldNY, CC BY-NC 2.0, sourced from Flickr.
Nowadays, ceramic materials that are not necessarily clay-based have been developed. These advanced ceramics are tough and hard-wearing and are being increasingly used in high-performance applications in engineering and medicine.
Science ideas and concepts
The overarching theme of our ceramics resources relates to the structure, properties and classification of matter, and these are the key science ideas and concepts identified:
What are ceramics? The traditional clay-based domestic wares, art objects and building products are just one part of the ceramic world. Nowadays, ceramic materials that are not necessarily clay-based have been developed. These advanced ceramics are being increasingly used in high-performance applications in engineering and medicine. This resource looks at the classification of ceramics.
What is clay? Since the earliest times, humankind has had a close association with clay. From use as a building material, in pottery and in a multitude of industrial settings, clay is a key ingredient in the material world we live in. Commercially, the most important clays are known as kaolin and bentonite. This resource looks at how clays were formed and their mineral makeup.
What are minerals? A mineral is an element or chemical compound, normally crystalline, that is found in rocks or as natural deposits in the Earth’s crust. Minerals are often used in the production of ceramics. This resource investigates the structural features and physical properties of common minerals. The mineral content of rocks is also considered.
Bone and tooth minerals The minerals found in human teeth and bones that give them their hardness and strength belong to a mineral family known as biological apatites. The biological apatites are forms of calcium hydroxyapatite, which has the formula Ca10(PO4)6(OH)2. This resource looks at the chemical and physical properties of this mineral as found in tooth enamel, dentine and bone. Bioceramics are used to replace these hard tissues in the body.
Temperature – the highs and lows Advanced ceramic materials are produced from powders heated to very high temperatures. The process is called ‘sintering’. For ceramic superconductors to operate effectively, they need to be cooled to very low temperatures known as the ‘critical temperature’. This resource looks at temperature, temperature scales, and the highs and lows required in the advanced ceramic field.
The curriculum
The ceramic resources have links to these requirements in the curriculum:
Material World – levels 4–5: Linking the properties of different groups of substances to the way they are used in society or occur in nature.
Physical World – level 5: Explore a technological or biological application of physics.
The resources provide an opportunity to ‘capture’ arts-oriented students as it provides a link into the world of pottery by delving into the ‘old’ world of clay-based ceramics and the ‘new’ world of advanced ceramics.
Defining ceramics
Dr Ian Brown, a senior research scientist with Industrial Research Limited, explains how the term ‘ceramics’ now has a more expansive meaning. Traditional ceramics are clay-based, but high-performance or advanced ceramics are being developed from a far wider range of inorganic non-metal materials. Advanced ceramics have the properties of high strength, high hardness, high durability and high toughness.
Point of interest
Will ceramic car engines replace the current metal-based ones?
Acknowledgements:
Charlie Pfeifler
Natalija Luketic
NASA
Rich Kaszeta
Meet our scientists
Dr Ian Brown and Dr Nick Strickland are conducting advanced ceramic research at Industrial Research Limited (IRL) in Wellington. They’re at the forefront of developments in superconductive materials as well as thermal shock-resistant materials.
Dr Ian Brown
Dr Ian Brown placing O-Sialon samples in the isostatic press. Before high temperature firing, the O-Sialon sample is compacted using an isostatic press. This ensures that the sample particles are tightly packed together prior to sintering.
Dr Michael Mucalo at the University of Waikato is investigating bovine hydroxyapatite (basically, bone from cows) as a possible human bone repair material.
Teaching and learning activities
The activities have been developed to highlight the science ideas and concepts and focus on the structure, properties and classification of matter. Some relate directly to the scientist's research stories.
Minerals present in granite: identify the main minerals present in granite and investigate some of their properties.
Measuring the specific gravity of quartz: measure the specific gravity of a sample of the mineral quartz.
Crystal systems: investigate crystal shapes and crystal systems. Traditional ceramics are clay-based – clays have a mineral composition and minerals have a crystalline structure.
Investigating clay: investigate some of the properties of clay such as moisture content, shrinkage and strength.
Bone minerals: investigate how bone strength varies with its mineral content and the solubility of bone minerals in neutral and acidic solutions.
Bone strength: create artificial bones made of paper to compare the relative strength of solid bones with hollow bones.
Superconductivity – Bob Buckley interview: listen to a podcast of IRL superconductivity scientist Bob Buckley talking about this work and then answer a series of graded questions related to the content.
Meissner effect – Nick Strickland video clips: watch videos of Dr Nick Strickland talking about superconductivity and the Meissner effect and then answer a series of questions and solve some simple electrical problems related to the content.
Sialons – Ian Brown video clips: watch videos of Dr Ian Brown talking about sialons and then answer a series of graded questions related to the content.
Investigating temperature: view the interactive Temperature – the hot and the cold and participate in a class discussion.
Liquid nitrogen demonstrations: observe a teacher demonstrating changes in the properties of common substances when cooled with liquid nitrogen.
Question bank
The Ceramics – question bank provides a list of questions about ceramics and places where their answers can be found. The questions support an inquiry approach.
Key terms
For explanations of key concepts, see Ceramics – key terms.
Timeline
Explore the timeline to look at some of the historical aspects of advanced ceramics. Find out more about the advancements in engineering and medical frontiers using ceramics.
Nature of science
As our science knowledge base increases within a given field, narrow definitions that worked in the past may need to be expanded to include more recent discoveries. Ceramics is not just about pottery. It now includes materials like glass, advanced ceramics and some cement systems as well.
