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.

Bismuth based high Tc superconductors are among the materials that have been extensively appreciated in terms of their application. Since this type of superconductors are very sensitive with respect to synthesis process, here, we consider effect of synthesis process on the electrical, magnetic and superconducting properties of Pb-BSCCO compound. The samples were prepared by both solid state and sol-gel reaction. In both of the preparation routes, two different methods of Cold Press (CP) and Spark plasma sintering (SPS) were used to compress the samples after, the completion of their calcination and grinding. In the next step, the samples put through the thermal process of sintering with different temperatures with respect to their preparation method. The results of the measurements indicate better superconducting properties in sol-gel method compare to the solid-state method. Also, it indicates better superconducting properties in Cold Press samples with respect to the samples prepared by SPS method. To compare the sintering temperature indicates that 825 and 830 oC are suitable temperature for sol-gel and solid-state samples, respectively, in Cold Press process.

Background: The digital dentistry, requires materials with wo opposite properties of machining ability and also enough hardness. The main objective of this experimental study was to investigate the fabrication feasibility of the lithium metasilicate glass‑, ceramic in partially crystalized stated using the Spark plasma sintering (SPS) method. Materials and Methods: In this study, SPS for the first time was used to fabricate primary lithium metasilicate glass‑, ceramic (LMGC) blocks. The raw materials were mixed and melted and then quenched in water and the resulted frits were grinded. The resulting powder was sintered by SPS at 660, 680, and 700°, C. Results: Scanning Electron Microscope (SEM), X‑, ray diffraction (XRD), and Vicker’, s microhardness assay were used to evaluate the properties of samples. Statistical comparison of the obtained data was performed by ANOVA, followed by the post hoc test of Duncan. Microstructural studies by SEM and XRD showed that all samples were composed of lithium metasilicate phase in a glassy matrix. With increasing the sintering temperature, the number and size of lithium metasilicate particles increased and higher mechanical properties have been achieved. However, the sintered sample at 700°, C has less processing ability than the samples sintered at 660 and 680°, C. Conclusion: The optimum sintering temperature for glass frit consolidation was determined by SPS at 680°, C.

Aims: This study aimed to investigate the effects of simple shear extrusion following Spark plasma sintering on the microstructural and mechanical properties of commercially pure titanium for advanced biomedical applications. Materials & Methods: In this experimental study, commercially pure titanium samples were first fabricated using Spark plasma sintering at 900°C and were subsequently subjected to simple shear extrusion at room temperature. Microstructural analyses were performed using Williamson-Hall XRD calculations to evaluate grain size. Mechanical properties, including hardness and tensile strength, were assessed to determine the influence of the simple shear extrusion process. Findings: The grain size decreased significantly from 60.2 nm in the Spark plasma sintering-processed sample (first sample) to 27.9 nm in the simple shear extrusion-processed sample (second sample). Hardness increased from 373.2 HV in the first sample to 411 HV in the second sample, compared to the base titanium hardness of 315 HV. These findings demonstrate the simple shear extrusion process’s ability to refine the microstructure and enhance mechanical properties. Conclusion: The fusion of Spark plasma sintering and simple shear extrusion not only enhances the mechanical integrity and biocompatibility of titanium components but also establishes a solid foundation for developing next-generation medical implants.

The influence of mechanical activation by ball milling (BM) of Ti, B and graphite powders mixture on the synthesis of B4C-TiB2 (1: 1 mole ratio) composite by Spark plasma sintering (SPS) is investigated. The milled powders at 0, 3 and 8 h were chosen for investigation of synthesis mechanism, density and microstructure of powder and dense products. Results showed the milling influence on temperature and time of reactants conversion to products, but it does not have any effect on mechanism of synthesis. The synthesis process occurs through a solid-state diffusion mechanism where the first crystalline phase formed is TiB, which is gradually converted to TiB2, while the formation of B4C takes place subsequently. Investigation showed that with using 8 h milled reactant; nanostructure composite powder could be obtained. As a consequence of the mechanical treatment up to 8h, SPS product density increases from about 82% to 94% of the theoretical value. Correspondingly, a material with homogeneous phase distribution and grain submicron size is obtained.

ZrB2– SiC– ZrC nanocomposite was fabricated by Spark plasma sintering using ZrB2– SiC– ZrC synthesized powder by MA-SPS route. In the present research, sintering mechanism was investigated by displacement-temperature-time (DTT), displacement rate vs. temperature and displacement rate vs. time diagrams which were obtained during Spark plasma sintering cycles. sintering process of the composite was completed after 17 min at temperature of 1750° C. By using X-ray powder diffraction (XRD) pattern and Rietveld method, the mean crystallites sizes of about 77, 62 and 56 nm were calculated for ZrB2, SiC and ZrC phases, respectively. The physical and mechanical properties of sintered composite such as: density, tensile strength, Vickers hardness and fracture toughness were% 99/3, 563 MPa, 18 GPa and 4. 9 MPa. m1/2, respectively. Finally scanning electron microscopy (SEM) images show three different phases well distributed all over the sample. It is clear that ZrB2, SiC and ZrC phases are well connected and have good continuity.

In this research, fused silica-zirconia composites including of 5 % by weight of zirconia stabilized yettria prepared by Spark plasma sintering (SPS) method. The powders were mixed by Spex (8000D, High energy ball mill) for 30 min in ethanol media. After mixing process, the ethanol removed by heating of the batches at 70 °C. The prepared samples were sintered at 1100, 1200 and 1300 °C and final pressure of 30 MPa. FESEM images demonstrated distribution of reinforcements at the fused silica matrix, also the results showed that sintered samples at 1200 °C have better properties than other samples. Relative density, flexural strength, hardness and toughness of these samples were 99.99 %, 13.4 GPa, 131 MPa and 4.46 MPa.m1/2 respectively. Also results showed that with increasing of sintering temperature to 1300 °C, due to crystallization in fused silica and as a result the formation of cracks in matrix, flexural strength decreased but the hardness and toughness increased slightly.

In this research, a high entropy alloy of AlCoCrFeNiMn is made through mechanical alloying and the Spark plasma sintering processes. Ball milling was done at different times of 12 h, 36 h, and 48 h in a cup with a diameter of 20 cm. Ball to powder percent weight of 10: 1 was selected. X-ray diffraction patterns indicate the formation of solid solution microstructure after 48 h. The crystal size decreases from 23 to 16 nm with increasing milling time. The lattice strain of the structure increments from 0. 3 to 0. 68% with increasing time up to 48 h. SEM images clearly show the phenomenon of powder agglomeration and the absence of intermetallic compounds or brittle, complex structures. It is observed that with increasing ball-milling time, homogenization of powders increases, and the body-centered cubic phase is formed in the structure. The mechanically alloyed powders were consolidated Spark plasma sintered at 700, 900, and 1000 °, C. 50 MPa pressure, argon gas as atmosphere, and ten minutes as sintering time were selected as the sintering process parameters. The X-ray diffraction pattern shows that the structure of consolidated high entropy alloy has face-centered cubic and body-centered cubic phases. After sintering by the Spark plasma method, the density of powders was measured by Archimedes’,rules, and the value was determined as 99% of theoretical density. The structure was without porosity. The hardness was measured using the microhardness Vickers test. Loading force was 50 g and loading time was seven seconds. The highest hardness was about 649 HV0. 05.

In this research work, the effects of nano-diamond addition on densification and mechanical properties of 25 vol% SiC reinforced ZrB2-based ultra-high temperature composites were studied. In this way, a ZrB2– SiC composite (as the baseline) and three ZrB2– SiC-based composites doped with different amounts of nano-diamond additive (1, 2 and 3 wt% of matrix phase) were fabricated by Spark plasma sintering route. The sintering process was carried out at 1900 ° C for 7 min under 40 MPa. The addition of nano-diamond, up to 2 wt%, has not significantly affected the densification process because the 0-2 wt% nano-diamond reinforced samples reached their theoretical densities but the relative density of sample reinforced with 3 wt% diamond was less than 99%. The hardness of 0, 1, 2 and 3 wt% diamond reinforced ceramics were 19. 5, 23. 4, 24. 7 and 22. 2 GPa, respectively. All diamond reinforced samples were harder than the diamondfree one but the hardness slightly decreased by the addition of 3 wt% diamond. The fracture toughness linearly increased from 4. 3 MPa. m1/2 for diamond-free ceramic to 5. 8 MPa. m1/2 for3 wt% diamond reinforced sample. The sintering route was a reactive process as the nano-diamond was transformed to the graphite during the sintering and/or converted to the in-situ formed ZrC and B4C phases through the removal of oxide impurities from the surfaces of raw materials.

In this research, transparent polycrystalline spinel ceramic was fabricated without any sintering aids and by performing Spark plasma sintering method on a mixture of Al2O3 and MgO powders for only 10 min soak at 1250° C. Densification, microstructure and optical transparency of spinel were examined. The result indicate that spinel exhibits an in-line transmission of 55% for an IR-wavelength of 4. 7μ m and high hardness value of 2040 HV