Structural Ceramic Nanocomposites: A Review of Properties and Powders’ Synthesis Methods

Abstract

Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional properties, a deep understanding of the materials’ behavior across length scales is necessary. In fact, knowing how the nanoscale structure influences the bulk properties enables the design of increasingly performing composite materials. A further key point is the ability of tailoring the desired nanostructured features in the sintered composites, a challenging issue requiring a careful control of all stages of manufacturing, from powder synthesis to sintering. This review is divided into four parts. In the first, classification and general issues of nanostructured ceramics are reported. The second provides basic structure–property relations, highlighting the grain-size dependence of the materials properties. The third describes the role of nanocrystalline second-phases on the mechanical properties of ordinary grain sized ceramics. Finally, the fourth part revises the mainly used synthesis routes to produce nanocomposite ceramic powders, underlining when possible the critical role of the synthesis method on the control of microstructure and properties of the sintered ceramics.

Assessing Flexural Strength Degradation of New Cubic Containing Zirconia Materials

“…Smaller grains can limit the size of the dislocations on the crystal grain boundaries, thus increasing mechanical properties. 16,21,22 Based on the FS values, ISO standard 6872-2015 would grade the 5Y-PSZ groups as class 4 materials to be utilized as single-unit anterior or posterior prostheses or as a 3-unit anterior prosthesis. 23 After fatigue testing, Katana UTML, would be re-classified as a class 2 ceramic, with recommendation to be utilized as an adhesively cemented anterior or posterior single-unit crown owing to its significant decrease in strength.…”

Toughening and strengthening of ceramics composite through microstructural refinement

“…Further, the authors also has been reported that the SiC-ZrO 2 microstructure refinement with harmonic grain dispersion indicate superior mechanical properties [7,8]. Thus, if the composite can be made into a nano/nano or a nano/micro type, additional improvement in toughness and strength can be expected because of the change of fracture mode of the composite which act to deflect or stop the crack propagation [9], as shown in Fig. 2.…”

Enhanced toughness of zirconia ceramics with graphene platelets consolidated by spark plasma sintering

“…Much effort has been paid to improve fracture toughness of ceramics using micro‐ and nanostructures as reinforcements. These methods have the similar aim of providing additional intrinsic grain boundaries or extrinsic interfaces that prohibit dislocation movement and long paths of crack propagation . Conventionally, one‐dimensional materials, including carbon fibers, carbon nanotubes, and silicon carbide whiskers, are used as the reinforcements in the ceramic matrix composites, in which fiber pullout, fiber bridging, and crack deflection are considered as the main toughening mechanisms.…”

“…These methods have the similar aim of providing additional intrinsic grain boundaries or extrinsic interfaces that prohibit dislocation movement and long paths of crack propagation. 1,2 Conventionally, one-dimensional materials, including carbon fibers, carbon nanotubes, and silicon carbide whiskers, are used as the reinforcements in the ceramic matrix composites, in which fiber pullout, fiber bridging, and crack deflection are considered as the main toughening mechanisms. Although the above toughening mechanisms have changed crack paths and thus enhanced fracture toughness of ceramics, they can come into play in only one-dimensional direction.…”