In this work, lithium meta titanate (Li2 TiO3 ) nanocrystallites were synthesized by the hydrothermal method and subsequent heat treatment. The shrinkage of the powder compact was measured under constant heating rate in order to study the SINTERING behavior of the synthesized powders. The densication curves of the synthesized powders were also constructed via the dilatometry analysis and evaluated at several heating rates. Two separate methods, including analytical procedure and master curve SINTERING were employed to determine the activation energy of the initial SINTERING stage. Results showed that activation energy values obtained from these two distinct methods (229± 14 and 230 kJ/mol, respectively) were consistent with each other. It was revealed that the dominant mechanism of densication on initial SINTERING of Li2 TiO3 nanocrystallites is surface diffusion

In this study, Y3Al5O12-MgAl2O4 (YAG-Spinel) composites, with different molar ratios (1: 1 and 1: 3), were in-situ fabricated using Reactive Spark Plasma SINTERING (RSPS) technique. To this end, Al2O3, MgO, and Y2O3 powders were used as the starting materials. In-situ formation of YAG-Spinel composites was investigated based on the reaction 3. 5 Al2O3 + MgO + 1. 5 Y2O3 → Y3Al5O12 + MgAl2O4. Both synthesis and densification processes were accomplished using a single-cycle RSPS with one-step heating. The RSPS process was performed at a SINTERING temperature of 1300 ° C for 30 min hold time with a maximum uniaxial pressure of 90 MPa under vacuum conditions. The synthesized phases and microstructures were investigated by X-ray diffraction and field emission scanning electron microscopy. The unwanted phases such as YAP (YAlO3) in a composite microstructure were removed using LiF additive. LiF was used as a SINTERING aid in the process of SINTERING. The in-situ synthesized YAG-Spinel composites exhibited no internal infrared transmittance over the infrared wavelength ranges of 2. 5-25 μ m.

Liquid phase SINTERING of pure nickel and titanium powders was used in this research to produce samples of Ni-Ti memory alloy (Nitinol). Effect of compaction pressure, volume fixation, SINTERING temperature and SINTERING time on porosity and percentage of the NiTi phase produced during SINTERING were investigated. Results showed that the effect of temperature and time on porosity depends on the compaction pressure and start and finish of the compound formation reactions during SINTERING. In order to reduce porosity and prevent volume change, the samples were refrained inside a rigid container (fixture). Although the fixture could cease the changing of the volume to some extent, formation of the new phases as well as post-solidification contraction of the samples caused an increase in porosity of the sample.

In this paper, the effects of porosity of pure Al and Al2024 matrix nanocomposites reinforced by carbon nanotubeson their final properties have been studied through SINTERING parameters such as temperature and consolidation methods. For this purpose, powder composite was prepared using flake powder metallurgy method, including the dispersion of particles with ultrasonic waves and chemical mixing. Consequently, the final parts were produced in two different strengthening procedures consisting of spark plasma SINTERING and cold press-SINTERING. Finally, the samples were treated under hot extrusion in order to improve the mechanical properties. The experiments of densitometry, hardness and metallography were performed on final products. It was concluded that the SPS method was a better technique for processing of nanocomposites to achieve the optimal properties and also, the porosity of SPS samples has been considerably decreased after hot extrusion as well as the increasing of their hardness. The hardness and porosity of Al-1.5%wt.CNT, produced by SPS plus hot extrusion steps, were measured 62.45 HB and 1% respectively. In order to investigate the formation of aluminum carbide at the interface of CNT fibers and matrix, Raman spectroscopy and XRD were used which no peak for formed carbide appeared in results of both experiments.