Synthesis and Sintering
ISSN / EISSN : 2564-0186 / 2564-0194
Published by: Synsint Research Group (10.53063)
Total articles ≅ 49
Latest articles in this journal
Synthesis and Sintering, Volume 2; https://doi.org/10.53063/synsint.2022.2383
In order to study the effects of sintering conditions on the properties of TiAl-based materials, two different compositions (TiAl-15 wt% Ti3AlC2 and TiAl-25 wt% Ti3AlC2) were chosen and manufactured by spark plasma sintering at 900 ºC/7 min and 1000 ºC/15 min. The results showed that increasing the MAX phase content had positive effect on the relative density and mechanical properties, but simultaneous increasing the temperature and holding time is more effective in improvement of properties. For TiAl-15 wt% Ti3AlC2 sample, the relative density, Vickers hardness, fracture toughness, and bending strength increased from 92.3%, 3.6 GPa, 10.9 MPa.m1/2, and 206 MPa to 95.2%, 4.5 GPa, 12.0 MPa.m1/2, and 336 MPa, respectively, as the sintering temperature and holding time increased from 900 ºC/7 min to 1000 ºC/15 min. In the case of TiAl-25 wt% Ti3AlC2 sample, increasing the sintering temperature and holding time from 900 ºC/7 min to 1000 ºC/15 min led to the improvement of relative density, Vickers hardness, fracture toughness, and bending strength from 92.8%, 4.1 GPa, 11.2 MPa.m1/2, and 270 MPa to 97.5%, 4.6 GPa, 11.8 MPa.m1/2, and 340 MPa, respectively.
Synthesis and Sintering, Volume 2; https://doi.org/10.53063/synsint.2022.23118
A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables were examined in order to obtain the optimum sample with the best milling behavior and potential sinterability. The structural studies were carried out using X-ray Diffractometer (XRD) and scanning electron microscopy (SEM). Crystallite size and lattice strain of the milled samples were examined by Scherrer and Williamson-Hall methods in order to finalize the investigation. The optimum milling time was found to be 60 minutes. In addition, a starch-containing sample with a fraction of 2.5 weight percent seemed to have the best microstructural properties, based on SEM observations and crystallite size assessments. Due discussions about the effective phenomena during the mechanical alloying were also included.
Synthesis and Sintering, Volume 2; https://doi.org/10.53063/synsint.2022.23119
In this paper, the variables of the pyrolysis operation such as temperature, time, and atmosphere were studied and optimized. At first, the effect of increasing pyrolysis time at lower temperatures was investigated to understand the mutual influence of pyrolysis time and temperature in enhancing the efficiency of B4C synthesis. Then, three pyrolysis atmospheres were selected to find the optimal conditions: burial method in box furnace (air), pyrolysis in tubular furnace (argon), and pyrolysis in box furnace (air). The pyrolyzed powders were finally located inside the tubular furnace at 1500 °C for 4 h under argon atmosphere to synthesize B4C ceramics. X-ray diffractometry (XRD) was employed to determine the optimal processing conditions. The temperature of 600 °C and the holding time of 2 h were selected as the optimal pyrolysis conditions. Meanwhile, the burial method was chosen as the best atmosphere despite having a higher percentage of impurity because of the much lower cost compared to the argon atmosphere.
Synthesis and Sintering, Volume 2; https://doi.org/10.53063/synsint.2022.23120
Every day several tons of glass dispose as waste. Glass waste, as a non-degradable waste, causes many environmental problems. Using glass waste powder in concrete as a partial substitute for cement has notable effects on the reduction of environmental pollutants, energy consumption, and concrete production costs. In this study, the impact of using waste glass powder in levels of 5, 10, 15, and 20 wt.% as a substitute for cement on the mechanical properties of concrete was evaluated. Chemical analysis of glass and cement samples was determined using X-ray fluorescence (XRF). The flexural and compressive strength of the samples were measured according to ISO 679, Methods of testing cement – Determination of strength, in 3, 7, 28, and 90 days. The results of the compressive strength test showed that the strength of concrete increases by the amount of used glass powder in the concrete composition. The highest value of compressive strength was obtained by the sample with 15 wt.% of glass powder.
Synthesis and Sintering, Volume 2, pp 120-124; https://doi.org/10.53063/synsint.2022.2389
The rapid advancement in information technology, communication, and electronic devices elevates the need to develop suitable materials for microwave absorption (MA) which should have the properties of an ideal microwave absorber. Porous activated carbon from agricultural wastes has piqued the interest of MA researchers due to their distinct properties such as good specific surface area, high dielectric loss, good electrical conductivity, and low density. Herein banana peel activated carbon was prepared by activating banana peel precursor with KOH and carbonizing at different temperatures. The difference in the porous structure with varying carbonization temperature was visible in the FESEM image, validated by BET analysis. The Banana Peel Activated carbon samples exhibited good microwave absorption performance, with BP-AC700 displaying a minimum Reflection Loss (RL) of −40.62 dB at 10.72 GHz & 3.0 mm thickness. In addition, the obtained effective absorption bandwidth of 3.5 GHz spanned through the X band frequency. This exceptional microwave absorption was attained due to the sample's good conductive loss and Porous favourable morphology. This study inspires the development of future facile functional agricultural waste-derived microwave absorbers.
Synthesis and Sintering, Volume 2, pp 110-119; https://doi.org/10.53063/synsint.2022.2397
Polypropylene (PP) represents a considerable proportion of polyolefins (PO) used in different industrial applications such as automobile components, textiles, packaging, insulation, medical devices, various housewares and household appliances due to its efficient cost, desirable mechanical, thermal and electrical properties, easy processability and recyclability. Because of its carbonaceous structure, PP is a highly flammable material with a LOI value of 18 that presents serious fire hazard. In this research, Intumescent flame retardant (IFR) and colemanite were added to polypropylene to compose 30% of the total mass of the polymeric compounds and the synergistic effect of colemanite with intumescent flame retardant (IFR) additive in PP was investigated by limiting oxygen index (LOI), glow wire test (GWT), UL-94 test and mechanical properties measurements. The LOI, UL 94 and glow wire test results showed that colemanite had a significant effect on flame retardancy and LOI value which can reach to 37.6 % with loading level of 2 wt.% colemanite at the total amount of flame retardant additives kept constant at 30 wt.%. Additionally, the PP/IFR compounds passed UL 94 V0 rating and both 750 °C and 850 °C glow wire tests and with 2-8 wt.% colemanite loading. According to TGA analyses, the results indicated that colemanite improved the thermal stability of PP/IFR compounds and also promoted the formation of char layer. When colemanite mineral added to polypropylene without IFR system, it has no effect on flame retardancy properties of polypropylene. When all properties have been taken into consideration, colemanite can be used up to 6 wt% in IFR.
Synthesis and Sintering, Volume 2, pp 105-109; https://doi.org/10.53063/synsint.2022.2396
Aluminum-doped zinc oxide thin film (Al:ZnO) was derived by the sol-gel dip-coating technique to analyze the doping effect on the film’s crystal structure and optical transparency. The surface structure of the thin film had the particles in the nano-spherical form. Al amount changed surface roughness with the variation of the grain size. The crystal structure of ZnO was wurtzite (in XRD analysis). The surface morphology of the film was also examined with SEM images. The effect of Al doping was investigated to evaluate the necessary amount of Al on the optical properties. The films show high optical transparency (~85%) at specific Al doping amounts (0.8-1.6%).
Synthesis and Sintering, Volume 2, pp 84-91; https://doi.org/10.53063/synsint.2022.22116
The present work aims to prepare a dense cordierite-based glass-ceramic through slip casting and consequent heat treatment procedures. In this regard, sintering conditions were considered as the key variables to improve the properties of the glass-ceramic. For this purpose, glass frit powder was prepared through melting oxide powders (in the system of SiO2-Al2O3-TiO2-K2O-CaO-MgO). The mixed powders were then heat treated at 1450 °C for 1 hour and quenched in water. The glass frit powder was slip cast using the appropriate dispersant. Sintering was carried out by one-step, two-step, and three-step procedures. Specimens were characterized in terms of various analysis techniques including dilatometry, X-ray diffractometry, scanning electron microscopy, and mechanical strength measurement. Among the examined specimens, the sample sintered by a three-step approach was considered the optimized one which attained zero porosity. According to the obtained results, cordierite crystals were observable in this glass-ceramic matrix. A low coefficient of thermal expansion and a low dielectric constant were observed for the optimized glass-ceramic sample. The obtained results confirmed that the homogenous distributions of crystalline phases are responsible for the appropriate and desirable properties of the prepared glass-ceramic.
Synthesis and Sintering, Volume 2, pp 99-104; https://doi.org/10.53063/synsint.2022.22103
In this study, the 4th part of a series of publications on the sintering and characterization of TiAl-Ti3AlC2 composite materials, the mechanical properties were measured and discussed. For this purpose, different contents of synthesized Ti3AlC2 reinforcement (10, 15, 20, 25, and 30 wt%) were added to metallic Ti and Al powders, then ball-milled and manufactured by spark plasma sintering (SPS) for 420 s at 900 ºC under 40 MPa. Flexural strength, fracture toughness and Vickers hardness were measured by 3-point technique, SENB method, and indentation technique, respectively. Increasing the Ti3AlC2 content resulted in improvement of the mechanical properties, so that TiAl-25 wt% Ti3AlC2 composite showed the best flexural strength and Vickers hardness (270 MPa and 4.11 GPa, respectively). Increasing amount of Ti3AlC additive had no significant effect on fracture toughness. Densification improvement, in-situ formation of Ti2AlC, and limitation of grain growth were recognized as the reasons of mechanical properties enhancement. In contrast, further addition of Ti3AlC2 (30 wt%) decreased the mechanical properties due to the reduction of density and formation of more Ti2AlC agglomerates in grain boundaries.
Synthesis and Sintering, Volume 2, pp 92-98; https://doi.org/10.53063/synsint.2022.2280
This study investigates the effects of adding clay and fireclay on the physical and mechanical properties of magnesia-based refractories such as contraction, bending strength, bulk density, and apparent porosity. Domestic raw materials were used for the preparation of samples fired at 1350, 1450, and 1550 °C for 2 h. Adding clay exhibited no significant effect on the density and porosity, whereas adding fireclay had a remarkable influence on the shrinkage. Nevertheless, the effects of clay and fireclay on the strength of magnesia were unnoticeable. X-ray diffraction results showed that, after firing, the main phase compositions of the samples with clay addition were periclase and forsterite. Adding fireclay led to the synthesis of magnesite spinel, which can be attributed to the high alumina content. Based on scanning electron microscopy, no liquid phase was formed indicating that the sintering was a solid-state evolution with the synthesis of forsterite.