Preparation of silicon carbide/carbon fiber composites through high-temperature spark plasma sintering

This study discusses the potentials of spark plasma sintering (SPS) integrated with high temperature process that can enable sintering of SiC/Cf composites without any sintering aids. The random distribution of carbon fibers was obtained through mixing composite components in ethanol by using a shaker mill for 10 min. The corresponding sintering process was carried out at 1900 and 2200 °C with 50 MPa pressure applied at maximum temperature. The results showed that 89 ± 0.9 and 97 ± 0.8% of the theoretical density can be obtained for sintering temperatures of 1900 and 2200 °C, respectively. The densification curves were plotted to monitor sintering behavior with punch displacement changes. The appropriate bonding between SiC particles and carbon fibers was detected using FE-SEM for sample which was sintered at 2200 °C. The clear maximum in hardness (2992 ± 33 Vickers), bending strength (427 ± 26 MPa) and fracture toughness (4.2 ± 0.3 MPa m1/2) were identified for sample sintered at 2200 °C. XRD investigations supposed that SiC and carbon were the only crystalline phases in both sintered samples

Sintering behavior and microwave dielectric properties of nano zinc niobate powder

Nanosized ZnNb2O6 powders obtained by high energy ball milling (HEBM) and subsequent heat treatment were compacted and sintered into near full density ceramics using pressureless sintering. The prepared ceramic samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and microwave dielectrical property measurements. All samples prepared at sintering temperatures ranging from 975 to 1100 degrees C, exhibit a single columbite phase and their relative densities range from similar to 87% to similar to 99%. The variation trend of permittivity and Q x f value was in accordance with variation trend of relative density. Pure columbite ZnNb2O6 ceramic sintered at 1050 degrees C for 5 h exhibited good microwave dielectric properties with a permittivity about 23.6, Q x f value about 72,357 GHz, and temperature coefficient of resonant frequency about -67.72 ppm/degrees C. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Vanadium carbide reinforced aluminum matrix composite prepared by conventional, microwave and spark plasma sintering

The effect of sintering method on the structure and mechanical properties of aluminum −10 wt% VC composite was investigated. Aluminum-VC metal matrix composite was prepared successfully by conventional (at 600 °C), microwave (at 600 °C) and spark plasma sintering (at 450 °C). The obtained results indicate that the aluminum −10 wt% VC composite prepared by SPS had the highest relative density (99 ± 0.6 ± %TD), bending strength (295 ± 15 MPa) and microhardness (232 ± 16 Vickers). The XRD investigations showed the decomposition of VC phase and the formation of Al3V intermetallic phase in the microwave-sintered samples. The SEM micrographs and EDS analyses revealed uniform distribution of reinforcement particles in SPS method and the formation of Al3V phase in microwave-sintered sample