Ceramics

Ceramics are inorganic, nonmetallic materials held together by ionic and/or covalent bonds. They include oxides (for example alumina, zirconia), carbides, nitrides and silicates, as well as composites that combine ceramic phases with polymers, metals or other ceramics. The high bond strength of ceramic lattices gives rise to properties such as high hardness, thermal and chemical stability, and resistance to wear and corrosion. At the same time, their lack of mobile electrons and inability to undergo extensive plastic deformation make ceramics electrical insulators and intrinsically brittle under tensile loading. Ceramics are manufactured primarily from fine powders through pressing, extrusion or slip casting, followed by sintering at temperatures typically two-thirds of their melting points. During sintering, mass transport mechanisms—grain‐boundary, surface and lattice diffusion—cause densification, grain growth and neck formation. The resulting microstructure, defined by grain size, phase composition, residual porosity and grain-boundary phases, determines mechanical performance. Fine‐grained, fully dense ceramics can achieve high compressive strengths (up to several gigapascals) but remain sensitive to flaws; transformation-toughened ceramics (for example yttria-stabilised zirconia) exploit phase transformations to introduce compressive residual stresses and impede crack propagation. Porosity, whether engineered or residual, influences properties such as thermal insulation, permeability and strength. The combination of tailored chemistry, controlled processing and microstructural design underpins a broad range of applications in structural components, cutting and wear parts, biomedical implants, energy devices, environmental barriers and electronic substrates.

Research from Nature Portfolio

High-surface-area corundum nanoparticles have been synthesised by rapid pulsed-current Joule heating of γ-alumina powders. Localised resistive hotspots in a sub-second thermal pulse drive a topotactic transformation to α-Al₂O₃ via an intermediate δ′ phase, yielding ~23 nm particles with ~65 m² g⁻¹ surface area. The process reduces energy consumption and produces sintered ceramics whose nanograined microstructure approaches sapphire hardness.

Unidirectional porous ceramics produced by ice-templating exhibit mechanical behaviour consistent with a honeycomb out-of-plane model. Compressive strength in samples with 45–80 % porosity is shown to depend exclusively on total porosity when wall buckling dominates failure. Independent control of macroporosity and wall densification via solids loading and sintering temperature enables optimisation of strength up to 286 MPa in low-porosity specimens.

Research from all publishers

A reverse particle-grading strategy for porous silicon carbide supports arranges coarse and fine powders to enhance neck formation during sintering. This graded structure promotes load transfer across the skeleton, leading to flexural strengths increased by up to 30 % at constant open porosity, thus improving mechanical robustness for high-temperature filtration.

Sustainable fabrication of SiC supports is achieved by incorporating activated coke fly ash as both sintering aid and pore-forming agent. The fly ash minerals facilitate densification around pore walls and refine microstructure, yielding supports with bending strength ~28.6 MPa—25 % higher than conventional SiC—and excellent thermal shock and alkali corrosion resistance after repeated cycling.

Hierarchically porous SiC ceramics have been produced by a foaming method in which controlled addition of hydrogen peroxide and surfactant yields uniform bimodal pores. Adjustment of foaming temperature and agent content tunes pore size, interconnectivity and bulk density, enabling ceramics with ~56 % porosity, ~12 MPa flexural strength and corrosion resistance suitable for harsh chemical environments.

Ceramics publication trend

The graph below shows the total number of articles in ceramics across all publications each year (not limited to Nature Index journals).

Technical terms

Sintering: Thermal consolidation of a powder compact by atomic diffusion, reducing porosity and strengthening particle bonds.

Porosity: Volume fraction of voids in a material; influences mechanical strength, permeability and thermal conductivity.

Grain boundary: Interface between adjacent crystalline domains that affects diffusion, toughness and electrical behaviour.

Transformation toughening: Enhancement of fracture resistance when stress-induced phase changes generate compressive stresses around cracks.

Neck formation: Localised bonding between adjacent particles during the initial stages of sintering that initiates densification.

Phase transformation: Change in crystal structure (for example tetragonal to monoclinic zirconia) that can alter volume and mechanical properties.

Liquid phase sintering: Densification mechanism in which a transient liquid phase fills pores and promotes particle rearrangement and bonding.

References

1. Pressure effect on long-term heat storage ceramics based on Mg-substituted λ-Ti 3 O 5. Materials Advances (2022).
2. High-surface-area corundum nanoparticles by resistive hotspot-induced phase transformation. Nature Communications (2022).
3. Mechanical properties and failure behavior of unidirectional porous ceramics. Scientific Reports (2016).
4. Activated coke fly ash-aided SiC supports: Enhanced mechanical strength and durability for high-temperature gas filtration. Advanced Membranes (2025).
5. Fabrication of SiC Porous Ceramics by Foaming Method. Materials (2023).