A new super-strong ceramic material — inspired by the mother-of-pearl created by the single-shelled marine mollusks known as abalones — has been created by a team of researchers led by the Laboratoire de Synthèse et Fonctionnalisation des Céramiques.
This new “artificial mother-of-pearl” is considerably less prone to fracture than conventional ceramics, as well as being nearly 10 times stronger. The material retains its properties even when exposed to rather high temperatures — up to at least 600°C.
These qualities are largely down to the use of a new, innovative manufacturing process, that utilizes a freezing step. Importantly, this new approach is highly compatible with large-scale industrialization, and isn’t appreciably more expensive than the techniques currently in widespread use.
The researchers think that the material could help to reduce the weight/size of ceramic elements in motors and/or energy generation technologies — thereby helping to reduce costs. Armor plating featuring the material is another option.
The press release from Le Centre national de la recherche scientifique (CNRS) provides more:
Mother-of-pearl, which covers the shells of abalone and some bivalves, is 95% composed of calcium carbonate (aragonite), an intrinsically fragile material that is nonetheless very tough. Mother-of-pearl can be seen as a stack of small bricks, welded together with mortar composed of proteins. Its toughness is due to its complex, hierarchical structure where cracks must follow a tortuous path to propagate. It is this structure that inspired the researchers.
As a base ingredient, the team from the Laboratoire de Synthèse et Fonctionnalisation des Céramiques (CNRS/Saint-Gobain) used a common ceramic powder, alumina, in the form of microscopic platelets. To obtain the layered mother-of-pearl structure, they suspended this powder in water. The colloidal suspension (1) was then cooled to obtain controlled ice crystal growth, causing alumina to self-assemble in the form of stacks of platelets. The final material was subsequently obtained from a high temperature densification step.
This artificial mother-of-pearl is ten times tougher than a conventional alumina ceramic. This is because a crack has to move round the alumina “bricks” one by one to propagate. This zigzag pathway prevents it from crossing the material easily.
Of course, there are a great number of materials other than alumina that can be used, so the process can be tailored to any number of different purposes. So long as you’ve got a ceramic powder, in the form of platelets, that can self-assemble in a similar way, then you can use this process.
The new findings are detailed in a paper published in the journal Nature Materials.