Mechanical Properties of Si₃N₄‐SiC Three‐Layer Composite Materials

Abstract

The effects of microstructure and residual stress on the mechanical properties of Si 3 N 4 -based three-layer composite materials were investigated. The microstructure of each layer was controlled by the addition of two differently sized silicon carbides: fine SiC nanoparticles (∼200 nm) or relatively large SiC platelets (∼20 µm). When the SiC nanoparticles were added, the average grain size of Si 3 N 4 was reduced because of the inhibition of grain growth by the particles. On the other hand, when the SiC platelets were added, the microstructure of Si 3 N 4 was not much changed because of the large size of the platelets. Three-layer composites were fabricated by placing the Si 3 N 4 /SiCnanoparticle layers on the surface of the Si 3 N 4 /SiC-platelet layer. The residual stress was controlled by varying the amount of SiC added. The mechanical properties of threelayer composites with various combinations of microstructure and residual stress level were investigated.

Grain Growth Phenomena in the Interface Region of α‐Alumina Bilayer Composites

“…L AYERED ceramic composites offer an opportunity to improve toughness and contact damage resistance of ceramic materials through appropriate design of composition and microstructure of constituent layers and interface conditions. [1][2][3][4][5][6][7][8][9][10][11][12] The composites exhibit a combination of properties derived from overlayers and underlayers, [1][2][3][7][8][9][10][11] which are desired in many engineering applications, such as ceramic bearings, cutting tools, and engine components. Al 2 O 3 -based [2][3][4][5][6][7] and Si 3 N 4 -based [7][8][9]13 layer composites are examples in which overlayers can be produced with a relatively homogeneous microstructure (fine grains with relatively low internal stresses), designed for hardness and wear resistance, while underlayers may have a more heterogeneous microstructure (coarse and/or anisotropic grains, usually with relatively high internal stresses), designed for toughness and damage dispersion.…”

Effects of Al2O3 platelet and VC additive on sintering and mechanical properties of WC-based composites by hot pressing

“…However, platelet reinforcement has been suggested as an alternative to whisker reinforcement [8] since it minimises health hazards and improves environmental safety, production economics and thermal stability, compared with whiskers. Experimental studies and models indicate that the toughening improvement by platelet addition is based on the contribution of several mechanisms, including debonding, pull-out (platelet sliding), crack bridging, microcrack formation and crack deflection at the platelet-matrix interface, load transfer as well as thermal residual stresses [9][10][11][12][13]. The critical characteristics of the interface can be summarised in terms of low interfacial fracture energy and moderate interfacial sliding resistance after debonding [14].…”

“…There have been many recent reports on composite reinforced by SiC platelet and several papers on composites reinforced by Al 2 O 3 platelet. SiC platelets were successfully used as reinforcements for some ceramics including Alumina (Al 2 O 3 ) [8,9] and Si 3 N 4 [10], and Al 2 O 3 platelet were successfully used as reinforcements for some composites like mulite matrix ceramic [11], X-Sialon ceramic [12] and glass matrix composites [13][14][15], but using Al 2 O 3 platelets (Al 2 O 3pl ) as reinforcements for WC basic composites was rarely reported.…”

Oxidation Behavior of SiC Platelet‐Reinforced ZrB2 Ceramic Matrix Composites

“…The SiC reinforcements such as whiskers, 9 particles, 10 or fibers 11 were used in previous studies, but using SiC platelets (SiC pl ) as reinforcements for ZrB 2 ceramics was rarely reported. SiC platelets were successfully used as reinforcements for some ceramics including Al 2 O 3 12,13 and Si 3 N 4 , 14 and obvious reinforcing effects were obtained. Therefore, it is expected that incorporating SiC platelets into ZrB 2 ceramics would improve the mechanical properties and oxidation resistance of the ZrB 2 ceramics.…”