Editing Ceramic (section)

===Mechanical properties===
[[File:Ultra-thin separated (Carborundum) disk.jpg|thumb|Cutting disks made of [[silicon carbide]] ]]
Mechanical properties are important in structural and building materials as well as textile fabrics. In modern [[materials science]], fracture mechanics is an important tool in improving the mechanical performance of materials and components. It applies the [[physics]] of [[stress (mechanics)|stress]] and [[Deformation (mechanics)|strain]], in particular the theories of [[Elasticity (physics)|elasticity]] and [[Plasticity (physics)|plasticity]], to the microscopic [[crystallographic defects]] found in real materials in order to predict the macroscopic mechanical failure of bodies. [[Fractography]] is widely used with fracture mechanics to understand the causes of failures and also verify the theoretical [[failure]] predictions with real-life failures.

Ceramic materials are usually [[ionic bond|ionic]] or [[covalent]] bonded materials. A material held together by either type of bond will tend to [[Fracture#Brittle|fracture]] before any [[plastic deformation]] takes place, which results in poor [[toughness]] and brittle behavior in these materials. Additionally, because these materials tend to be porous, the [[porosity|pore]]s and other microscopic imperfections act as [[Stress concentration|stress concentrators]], decreasing the toughness further, and reducing the [[tensile strength]]. These combine to give [[catastrophic failure]]s, as opposed to the more ductile [[failure mode]]s of metals.

These materials do show [[plasticity (physics)|plastic deformation]]. However, because of the rigid structure of crystalline material, there are very few available slip systems for [[dislocation]]s to move, and so they deform very slowly.

To overcome the brittle behavior, ceramic material development has introduced the class of [[ceramic matrix composite]] materials, in which ceramic fibers are embedded and with specific coatings are forming fiber bridges across any crack. This mechanism substantially increases the fracture toughness of such ceramics. Ceramic [[disc brake]]s are an example of using a ceramic matrix composite material manufactured with a specific process.

Scientists are working on developing ceramic materials that can withstand significant deformation without breaking. A first such material that can deform in room temperature was found in 2024.<ref>{{cite journal |title=The first bulk ceramic that deforms like a metal at room temperature |journal=Nature |date=23 February 2024 |doi=10.1038/d41586-024-00443-8 |pmid=38396100 }} summarizing {{cite journal |last1=Wu |first1=Yingju |last2=Zhang |first2=Yang |last3=Wang |first3=Xiaoyu |last4=Hu |first4=Wentao |last5=Zhao |first5=Song |last6=Officer |first6=Timothy |last7=Luo |first7=Kun |last8=Tong |first8=Ke |last9=Du |first9=Congcong |last10=Zhang |first10=Liqiang |last11=Li |first11=Baozhong |last12=Zhuge |first12=Zewen |last13=Liang |first13=Zitai |last14=Ma |first14=Mengdong |last15=Nie |first15=Anmin |last16=Yu |first16=Dongli |last17=He |first17=Julong |last18=Liu |first18=Zhongyuan |last19=Xu |first19=Bo |last20=Wang |first20=Yanbin |last21=Zhao |first21=Zhisheng |last22=Tian |first22=Yongjun |title=Twisted-layer boron nitride ceramic with high deformability and strength |journal=Nature |date=22 February 2024 |volume=626 |issue=8000 |pages=779–784 |doi=10.1038/s41586-024-07036-5 |pmid=38383626 |pmc=10881384 |bibcode=2024Natur.626..779W }}</ref>

====Ice-templating for enhanced mechanical properties====
If a ceramic is subjected to substantial mechanical loading, it can undergo a process called [[Freeze-casting|ice-templating]], which allows some control of the [[microstructure]] of the ceramic product and therefore some control of the mechanical properties. Ceramic engineers use this technique to tune the mechanical properties to their desired application. Specifically, the [[Strength of materials|strength]] is increased when this technique is employed. Ice templating allows the creation of macroscopic pores in a unidirectional arrangement. The applications of this oxide strengthening technique are important for [[solid oxide fuel cell]]s and [[Water purification|water filtration]] devices.<ref>{{cite journal |last1=Martinić |first1=Frane |last2=Radica |first2=Gojmir |last3=Barbir |first3=Frano |title=Application and Analysis of Solid Oxide Fuel Cells in Ship Energy Systems |journal=Brodogradnja |date=31 December 2018 |volume=69 |issue=4 |pages=53–68 |doi=10.21278/brod69405 |s2cid=115752128 |doi-access=free |url=https://hrcak.srce.hr/file/306607 }}</ref>

To process a sample through ice templating, an aqueous [[Colloid|colloidal suspension]] is prepared to contain the dissolved ceramic powder evenly dispersed throughout the colloid,{{clarify|reason=is the powder in suspension or actually dissolved?|date=December 2019}} for example [[yttria-stabilized zirconia]] (YSZ). The solution is then cooled from the bottom to the top on a platform that allows for unidirectional cooling. This forces ice crystals to grow in compliance with the unidirectional cooling, and these ice crystals force the dissolved YSZ particles to the solidification front{{clarify|date=June 2023}} of the solid-liquid interphase boundary, resulting in pure ice crystals lined up unidirectionally alongside concentrated pockets of colloidal particles. The sample is then heated and at the same the pressure is reduced enough to force the ice crystals to [[Sublimation (phase transition)|sublime]] and the YSZ pockets begin to [[Annealing (metallurgy)|anneal]] together to form macroscopically aligned ceramic microstructures. The sample is then further [[Sintering|sintered]] to complete the [[evaporation]] of the residual water and the final consolidation of the ceramic microstructure.{{citation needed|date=December 2019}}

During ice-templating, a few variables can be controlled to influence the pore size and morphology of the microstructure. These important variables are the initial solids loading of the colloid, the cooling rate, the sintering temperature and duration, and the use of certain additives which can influence the microstructural morphology during the process. A good understanding of these parameters is essential to understanding the relationships between processing, microstructure, and mechanical properties of anisotropically porous materials.<ref>{{cite journal |last1=Seuba |first1=Jordi |last2=Deville |first2=Sylvain |last3=Guizard |first3=Christian |last4=Stevenson |first4=Adam J. |title=Mechanical properties and failure behavior of unidirectional porous ceramics |journal=Scientific Reports |date=14 April 2016 |volume=6 |issue=1 |pages=24326 |doi=10.1038/srep24326 |pmid=27075397 |pmc=4830974 |bibcode=2016NatSR...624326S }}</ref>