An investigation of the thermal expansion behavior of ceramic fibrous monoliths (FMs) is presented. The emphasis is on the development and validation of material models applicable to Si3N4/BN FMs in both unidirectional and cross-ply architectures. Approximate analytical models are developed for the coefficient of thermal expansion (CTE) based on the analysis of representative unit cells of the ...

A variety of superhard coatings with Vickers plastic hardness exceeding 40 GPa have been reported by several research groups during the last five years (for recent reviews see refs [1,2]). However, one has to distinguish between superhard nanocomposites, such as nc-TiN/a-Si3N4, nc-TiN/a-Si3N4/aand nc-TiSi2, nc-(Ti1-xAlx)N/a-Si3N4, nc-TiN/TiB2, ncTiN/BN, etc. where the high hardness originates f...

Amorphous Si–(B–)C–N polymer-derived ceramics (PDCs) with a boron contentranging from 0 to 8.3 at.% were synthesized by thermolysis of the boron-modifiedpoly(methylvinylsilazane). Correlation of the boron content and the thermal stability ofthese materials in the course of annealing were investigated using high temperaturethermal gravimetric analysis (HT-TGA). Furthermore, t...

Six types of diamond-like carbon (DLC) coatings with zirconium (Zr)-containing interlayers on titanium alloy (Ti-6Al-4V) were investigated for improving the biotribological performance of orthopedic implants. The coatings consist of three layers: above the substrate a layer stack of 32 alternating Zr and ZrN sublayers (Zr:ZrN), followed by a layer comprised of Zr and DLC (Zr:DLC), and finally a...

A 16-channel 200 GHz arrayed-waveguide grating (AWG) (de)-multiplexer is demonstrated experimentally by utilizing Si3N4 buried optical waveguides, which have 50 nm-thick Si3N4 cores and a 15 μm-thick SiO2 cladding. The structure with an ultra-thin core layer helps to reduce the scattering due to the sidewall roughness and consequently shows very low loss of about 0.4~0.8 dB/m. When using this t...

In this work a novel, high quality, high-density, 100% yield, deposited at room temperature ultra thin 5nm Si3N4 Metal Insulator Metal (MIM) capacitor process for Monolithic Millimetre-wave Integrated Circuits (MMMICs) applications is demonstrated using inductively coupled plasma enhanced chemical vapor deposition technique (ICP-CVD). Capacitance of 6.7fF/μm and a breakdown electric field of mo...

The choice of ceramic-on-ceramic coupling in total hip prosthesis has advantages over couplings with other combinations materials that use polyethylene and metal terms high hardness, scratch resistance, low wear rate, increased lubrication performance. To reduce the risk primary postoperative failure, selection ceramic for is a strategic step needs to be taken. current study aims analyze common...

Silicon nitride–zirconia–graphene composites with high graphene content (5 wt.% and 30 wt.%) were sintered by gas pressure sintering (GPS). The effect of the multilayer (MLG) on microstructure fracture mechanism is investigated multi-scale in-situ microscopy. Multi-scale microscopy confirms that phases disperse evenly in without obvious agglomeration. MLG flakes well dispersed between ceramic m...

The effect of residual stresses on the strength, toughness and work of fracture of Si3N4/SiC multilayered composites with different SiC layers has been investigated. It may be an effective way to design and optimize the mechanical properties of Si3N4/SiC multilayered composites by controlling the properties of SiC layers. Si3N4/SiC multilayered composites with different SiC layers were fabricat...

The ceramic samples fabricated by spark plasma sintering of powder mixtures based on silicon nitride (Si3N4) were investigated. made wet chemical methods from commercial α-Si3N4 (the particle size <5 μm) and Y2O3-Al2O3 additive (3% to 10% wt.). Sintering was carried out at the heating rate 50 °C/min load 70 MPa until shrinkage end. characterized scanning electron microscopy X-ray diffraction...