scholarly journals Fabrication and Characterization of In Situ Synthesized SiC/Al Composites by Combustion Synthesis and Hot Press Consolidation Method

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Hongyu Yang ◽  
Erting Dong ◽  
Bingqi Zhang ◽  
Yanyan Yuan ◽  
Shili Shu
Keyword(s):  
Combustion Synthesis ◽  
Maximum Size ◽  
Holding Time ◽  
Mass Ratio ◽  
Hot Press ◽  
Uniform Size ◽  
Average Hardness ◽  
Sic Particles

The in situ SiC/Al composites were fabricated in Al-Si-C systems with different Si/C mass ratios and holding time by the method of combustion synthesis and hot press consolidation. The influences of Si/C mass ratio and holding time on the phase constitution, microstructure, and hardness of the composites were investigated. The results indicate that the increase of Si/C mass ratio leads to more uniform size distribution of the SiC particles in the Al matrix. Moreover, by improving the Si/C mass ratio from 4 : 1 to 5 : 1, the maximum size of SiC particle was reduced from 4.1 μm to 2.0 μm. Meanwhile, the percentage of submicroparticles was increased from 22% to 63%, and the average hardness value of the composites was increased by 13%. In addition, when the holding time is set to be fifteen minutes, the Al4C3 phase did not exist in the composites because of its total reactions with Si atoms to form SiC particles, and the average hardness value was 73.8 HB.

Effects of alloying elements on the phase constitution and microstructure of in situ SiC/Al composites

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940048 ◽  
Author(s):  
Hongyu Yang ◽  
Erting Dong ◽  
Bingqi Zhang ◽  
Liangyu Chen ◽  
Yunxue Jin ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Alloying Elements ◽  
Hot Press ◽  
Phase Constitution ◽  
Sic Particles ◽  
Effect Of Alloying

In this work, the in situ SiC/Al composites were successfully fabricated by the method of combustion synthesis and hot press consolidation in an Al-C-Si system. The effect of alloying elements (Mn, Zn, Ti) on the phase constitution and microstructure of in situ SiC/Al composites were investigated. Results indicated that the Al[Formula: see text]Mn[Formula: see text] and Ti[Formula: see text]Si[Formula: see text] phases were formed in the SiC/Al composites with the addition of Mn and Ti, respectively. By the addition of Mn, the size of the synthesized SiC particles was obviously reduced, and consequently the amount of SiC particles was increased. Meanwhile, the percentage of the submicro SiC particles increased about from 22% to 83%. However, the addition of Zn and Ti had little effect on the size of SiC particles.

scholarly journals Sodium Titanate Synthesis For The Photocatalytic Degradation of NO

2021 ◽  
Author(s):  
Marco Antonio Cueto Bastida ◽  
Yadira Guadalupe Maldonado ◽  
Yolanda Reyes Vidal ◽  
Myriam Solis Lopez ◽  
Eduardo Coutino Gonzalez ◽  
...  
Keyword(s):  
Flow Rate ◽  
Sodium Titanate ◽  
Photocatalytic Reduction ◽  
Mass Ratio ◽  
Hydrothermal Route ◽  
Reduction Of No ◽  
Oxide Phases ◽  
Photocatalytic Reduction Of No

Abstract The synthesis and characterization of sodium titanates (ST) and its evaluation in the photocatalytic reduction of nitric oxide (NO) is described in this contribution. The materials were synthesized by an hydrothermal route using the following parameters; 5 M NaOH concentration used as TiO2 mineralizer agent, under 170 °C for 48 hours, and a dose of TiO2 of 0.06 mg/mL (expressed as the mass ratio of TiO2/mL with respect to NaOH); resulting in tri- and hexa- ST. A nanotubular morphology was observed for the ST as proved by scanning electron microscopy (SEM) and a subsequent heat-treatment at 400 °C allowed a complete transformation of tri- to hexa- sodium titanates to modify the bandgap. The obtained ST were impregnated with Ag+ and Zn+ cations, respectively (ST-Ag, ST-Zn), to tune the bandgap of the materials. XPS analysis of the ST-Ag materials showed evidence of metallic Ag pointing to the formation of silver nanoparticles, whereas for ST-Zn oxide phases were mainly spotted. The materials were evaluated for the photocatalytic reduction of NO using a reactor fed with a continuous flow rate of NO, generated in situ, at a flow rate of 280 ml/min using nitrogen and a 253 nm wavelength UV irradiation source. The photocatalytic tests showed that pristine ST (tri and hexa-titanate) was the photocatalyst that displayed the best performance in the reduction of NO with respect to the impregnated samples (ST-Ag, ST-Zn). Maximum efficiencies of 80% degradation were reached when using 1 g of photocatalyst with a flow of 280 ml/min and a lamp of 253 nm.

Microstructure and Mechanical Properties of Graded Materials Prepared by Field-Activated and Pressure-Assisted Combustion Synthesis

2008 ◽  
Vol 368-372 ◽  
pp. 1876-1878 ◽  
Author(s):  
Qing Sen Meng ◽  
Shao Ping Chen ◽  
Y.L. Shen ◽  
Cui Rong Liu ◽  
Z.A. Munir
Keyword(s):  
Combustion Synthesis ◽  
Mechanical Characterization ◽  
Gradient Material ◽  
Micro Hardness ◽  
Hot Press ◽  
Rockwell Hardness ◽  
Graded Materials ◽  
Gradient Materials ◽  
Better Than

Using the processes of field-activated and pressure-assisted combustion synthesis (FAPACS), FGM materials (FGMs) were prepared under the conditions of field-assisted and the hot-press. The microstructure and the phase composition of the interface of the graded materials were investigated and the results showed that the metallurgical joining layer was formed in the interfaces of the (TiB2)pNi/Ni3Al/405 steel. The mechanical characterization of the gradient materials showed that the composition and the micro-hardness of the gradient material were gradient distributed, and its surface Rockwell hardness and wear resistance are better than that of hardened 20Cr steel.

Hot-Press Sintering Densification, Microstructure and Properties of SiC-TiB2/B4C Composites

2014 ◽  
Vol 602-603 ◽  
pp. 488-493 ◽  
Author(s):  
Bao Xin Zhu ◽  
Yu Jun Zhang ◽  
Hong Sheng Wang ◽  
Chong Hai Wang ◽  
Shuang Shuang Yue
Keyword(s):  
Bending Strength ◽  
Silicon Powder ◽  
Tetrabutyl Titanate ◽  
Second Phase ◽  
Hot Press ◽  
Microstructure And Properties ◽  
Sic Particles ◽  
Hot Press Sintering ◽  
Properties Of Composites

SiC-TiB2/B4C composites were fabricated by hot-press sintering B4C with silicon powder and tetrabutyl titanate (precursor of TiO2) as sintering and reinforcement agents. The influence of additives on hot-press sintering densification, microstructure and properties of composites were studied. The results showed that TiB2 and SiC generated by chemical reaction between additives and B4C matrix reinforced the sintering activity of the mixed powders and accelerated significantly the hot-press sintering densification rate of B4C from 1200 °C to 1700 °C. According to the SEM observation, the second phase of TiB2 and SiC particles synthetized in situ sited along the grain boundaries of B4C, meanwhile, those SiC particles of nanoscale size embedded into the B4C grains, and thereby, intra/inter-type ceramics formed. The maximum relative density of 98.1% was obtained with 9wt.% TiO2. The typical valus of Vickers hardness, bending strength and fracture toughness can reach 26.7 GPa, 580 MPa and 5.0 MPam1/2, respectively.

Synthesis and characterization of silver cluster particles in hydrogels

2015 ◽  
Vol 35 (4) ◽  
pp. 303-309
Author(s):  
Aman Deo ◽  
Syed Sauban Ghani
Keyword(s):  
Silver Cluster ◽  
Maximum Size ◽  
Spectrophotometric Analysis ◽  
E Coli ◽  
Hydrogel Network ◽  
Microscopy Analysis ◽  
Antibacterial Material ◽  
Spectroscopy Studies

Abstract A chitosan-based hydrogel network was crosslinked with genipin; the crosslinked and uncrosslinked hydrogels were prepared and studied. Uniformly distributed silver cluster particles (AgCPs) were prepared using these hydrogel networks as a carrier via in situ reduction of silver nitrate (AgNO3) in the presence of sodium borohydride (NaBH4) as a reducing agent; UV irradiation reduction was also done. Fourier transform infrared (FTIR) spectroscopy studies of the hydrogels gave results on the decree of crosslinking and some indication on the presence of the AgCPs. The spectrophotometric analysis indicated the presence of AgCPs, as a peak appeared around 400 nm. The microscopy analysis gave images of the presence of AgCPs and their size; it showed that the crosslinked hydrogels have uniformly distributed AgCPs and as the crosslinking increased, the AgCPs size decreased. The studies on the increasing concentration of AgNO3 solution gave an increase AgCPs size; the maximum size of AgCPs clusters was ∼0.2 micron in uncrosslinked chitosan. It was demonstrated, by using Escherichia coli (E. coli) bacterium, that the AgCPs hydrogel can be effectively employed as antibacterial material.

Development and Characterization of Novel Conductive Polypyrrole-Polylactide Open-Porous Composites

2009 ◽  
Author(s):  
Christine Chan ◽  
Weijia Zhang ◽  
Hani E. Naguib
Keyword(s):  
In Situ Polymerization ◽  
Compression Molding ◽  
Mass Ratio ◽  
Uncoated Sample ◽  
Salt Leaching ◽  
Mechanical And Electrical Properties ◽  
Mass Ratios ◽  
Porous Composites

Novel polypyrrole-polylactide blends were fabricated and characterized using compression molding, salt leaching, and in situ polymerization. Open-porous polylactide samples were fabricated using compression molding and salt leaching techniques with varying salt-to-polymer mass ratios of 3:1, 6:1, and 9:1. The samples then underwent in situ polymerization of pyrrole and iron (III) chloride to obtain a uniform coating of polypyrrole. Characterization of these novel composites comprised of their physical, mechanical, and electrical properties. With increasing salt-to-polymer mass ratio, it was found that the relative density decreased, the open porosity increased while pore size and pore density generally remained independent. The polypyrrole coating did not have a significant effect on the structure of the pore network. Microscopic polypyrrole nodules were observed to be uniformly coated on the surface and sub-surface of the composites. The compressive modulus decreased with increasing salt-to-polymer mass ratios. In addition, the modulus of the coated 3:1 salt-to-polymer mass ratio sample was twice the value obtained for the uncoated sample while the modulus values for the 6:1 and 9:1 samples did not significantly change. The conductivity increased as the salt-to-polymer mass ratio increased. The relationships observed between the structure and resulting properties provided the basis for future development and characterization of these novel porous composites.

Synthesis and Characterization of NaX Molecular Sieve Zeolite Films on Ceramic Paper for Membranes

2005 ◽  
Vol 492-493 ◽  
pp. 317-324
Author(s):  
Hae Jin Lee ◽  
Hyung Chul Kim ◽  
Ik Jin Kim
Keyword(s):  
Hydrothermal Method ◽  
Molecular Sieve ◽  
Mother Solution ◽  
Synthesis And Characterization ◽  
Uniform Size ◽  
Seed Crystals ◽  
Nax Zeolite ◽  
Zeolite Films

NaX molecular sieve films on ceramic paper prepared by in-situ hydrothermal method were investigated. The NaX zeolite seed crystals of a uniform size of 5 µm were synthesized by hydrothermal method in a mother solution having a composition of 3.5Na2O : Al2O3 : 2.1SiO2 : 500~1000 H2O. These dip-coated NaX seed crystal on ceramic paper lead to further the thickness (20 ~ 100 µm) of NaX film on the substrate at 90°C for longer 3~7 days in autoclave. Pure zeolite films consisting of a continuous intergrown of 5~ 20 µm NaX crystal have been prepared on the substrates. The zeolite films were characterized by XRD, SEM, BET and XRF.

scholarly journals Characterization of the Casein/Keratin Self-Assembly Nanomicelles

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Su Xiao-Zhou ◽  
Wang Hong-Ru ◽  
Huang Mian
Keyword(s):  
Self Assembly ◽  
Storage Stability ◽  
Mass Ratio ◽  
Scanning Calorimetry ◽  
Uniform Size ◽  
Force Microscopy ◽  
Atomic Force ◽  
Good Potential ◽  
And Storage

Complex nanomicelles were made from casein and keratin through electrostatic self-assembly and transglutaminase fixation that was proved to be harmless and green. The complex nanomicelles were characterized by dynamic light scattering, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and steady-state florescence. The results show that the complex nanomcelles acquired at the neutral pH in the mass ratio of casein to keratin 4 : 1 exhibit an anomalous sphere shape with uniform size which the diameter is about 40–70 nm. The complex nanomicelles in solution possess excellent dilution and storage stability due to the fixation and their highζ-potential (22.8 mV). The complex nanomicelles are relatively hydrophilic and have a good potential for industrial application.

scholarly journals Effect of Fe on the Microstructure and Mechanical Properties of Fe/FeAl2O4 Cermet Prepared by Hot Press Sintering

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 204
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Chuang Wang ◽  
Hongyan Yan ◽  
Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Raw Materials ◽  
Diffusion Reaction ◽  
Mass Ratio ◽  
Hot Press ◽  
Ceramic Phase ◽  
Microstructure And Mechanical Properties ◽  
Hot Press Sintering

The Fe/FeAl2O4 cermet was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method at 1400 °C. The raw materials for the powder particles were respectively 2 µm (Fe), 0.5 µm (Fe2O3), and 0.5 µm (Al2O3) in diameter, the sintering pressure was 30 MPa, and the holding time was 120 min. The effects of different Fe mass ratios on the microstructure and mechanical properties of Fe/FeAl2O4 cermet were studied. The results showed that a new ceramic phase FeAl2O4 could be formed by an in situ reaction during the hot press sintering. When the Fe mass ratio was increased, the microstructure and mechanical properties of the Fe/FeAl2O4 cermet showed a change law that initially became better and then became worse. The best microstructure and mechanical properties were obtained in the S2 sample, where the mass ratio of Fe-Fe2O3-Al2O3 was 6:1:2. In this Fe mass ratio, the relative density was about 94%, and the Vickers hardness and bending strength were 1.21 GPa and 210.0 MPa, respectively. The reaction mechanism of Fe in the preparation process was the in situ synthesis reaction of FeAl2O4 and the diffusion reaction of Fe to FeAl2O4 grains. The increase of the Fe mass ratio improved the wettability of Fe and FeAl2O4, which increased the diffusion rate of Fe to FeAl2O4 grains, which increased the influence on the structure of FeAl2O4.

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