scholarly journals Preparation and Characterization of Si3N4-BN Ceramic Composites by Gelcasting

2016 ◽  
Vol 13 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Nagaveni Thallapalli ◽  
K. Kishore Kumar ◽  
C. S. P. Rao
Keyword(s):  
Composite Material ◽  
Silicon Nitride ◽  
Boron Nitride ◽  
Aqueous Media ◽  
Ceramic Composites ◽  
Solution Ph ◽  
Gel Casting ◽  
Novel Method ◽  
Faceted Particles

In this work, a novel method for the preparation of colloids has been studied for the fabrication of silicon nitride –Boron nitride composites. In the present work, the dispersion of mixed silicon nitride –Boron nitride powders in aqueous media was studied with the changes dispersant concentration, solution pH etc. Polyethylenimine (PEI) additive as a dispersant were used for Si3N4 and BN powders in aqueous media. Well-dispersed Si3N4 and BN powders in aqueous media were attained atthe 1 wt% PEI and pH 9. 40 vol% covered Si3N4/BN slurries with varying BN content was adapted for gel casting. The gel casted material waspreheated at normal room temperature, debindered at 6000C and sintered at 17000C. The sintered composite material composed mainly of alpha-Si3N4, beta-Si3N4, and h-BN. The prepared composite material shows uniform microstructure with faceted particles, α-Si3N4 and abundant pores.

scholarly journals Synthesis and Characterization of Chitosan/Agar/SiO2 Nano Hydrogels For Removal of Amoxicillin and of Naproxen From Pharmaceutical Contaminants

2021 ◽  
Author(s):  
Omid Moradi ◽  
Samira Mhdavi ◽  
Sajjad Sedaghat
Keyword(s):  
Aqueous Media ◽  
Environmental Pollutants ◽  
Chemical Characterization ◽  
Solution Ph ◽  
Physical And Chemical Characterization ◽  
Pharmaceutical Contaminants ◽  
Living Organisms ◽  
Physical And Chemical

Abstract Today, environmental pollutants pose a threat to human societies and all living organisms, which is why they have attracted the attention of environmental researchers. In this study, in order to remove pharmaceutical contaminants Naproxen and Amoxicillin from aqueous media with SiO2 nanoparticles based on Agar and Chitosan was investigated. The study of structural properties, physical and chemical characterization of synthesized nanocomposite was investigated by FTIR, XRD, TEM, FE-SEM, DLS and EDX analyzes. In addition, the role of parameters affecting the removal of pharmaceutical contaminants such as solution pH, contact time, contaminant concentration and temperature were studied. Nanocomposites prepared from Agar and Chitosan showed good performance in absorbing naproxen and amoxicillin. According to the studies performed to remove naproxen, the max adsorption efficiency was obtained at a concentration of 20 mg/l with an absorbent dose of 0.05 g and a pH of 8 and at an optimum temperature of 25 °C and 99% in 15 min. Also, for amoxicillin with nanocomposite prepared with an initial concentration of 20 mg/l and an adsorbent dose of 0.05 g, a time of 10 min, a temperature of 25 °C and a pH of 8, the max removal efficiency of 91.15% was obtained.

Synthesis and properties of silicon/magnesium silicon nitride diatom frustule replicas

2014 ◽  
Vol 2 (39) ◽  
pp. 16410-16415 ◽  
Author(s):  
Ivar Andre Ødegård ◽  
Julien Romann ◽  
Anita Fossdal ◽  
Arne Røyset ◽  
Gabriella Tranell
Keyword(s):  
Silicon Nitride ◽  
Structural Characterization ◽  
Diatom Frustule ◽  
Metallothermic Reduction ◽  
Novel Method

A novel method for the conversion of diatom bio-silica structures into nano-porous 3D silicon/magnesium silicon nitride replicas utilising simultaneous metallothermic reduction and nitriding is described. Optical, chemical and structural characterization of the replicas is also presented.

Synthesis of Porous Silicon Nitride-Boron Nitride Composites by Gel-Casting and PIP

2014 ◽  
Vol 23 (8) ◽  
pp. 2829-2833 ◽  
Author(s):  
Kun Liu ◽  
Changrui Zhang ◽  
Bin Li ◽  
Siqing Wang ◽  
Feng Cao
Keyword(s):  
Silicon Nitride ◽  
Porous Silicon ◽  
Boron Nitride ◽  
Gel Casting

Silicon nitride/boron nitride ceramic composites fabricated by reactive pressureless sintering

2009 ◽  
Vol 35 (6) ◽  
pp. 2155-2159 ◽  
Author(s):  
Bo Yuan ◽  
Ji-Xuan Liu ◽  
Guo-Jun Zhang ◽  
Yan-Mei Kan ◽  
Pei-Ling Wang
Keyword(s):  
Silicon Nitride ◽  
Boron Nitride ◽  
Ceramic Composites ◽  
Pressureless Sintering

A Novel Method to Improve the Dispersibility of Silicon Nitride Powders in Aqueous Media

NANO ◽  
2019 ◽  
Vol 14 (09) ◽  
pp. 1950118
Author(s):  
Bingjie Xu ◽  
Mengxing Li ◽  
Qi Chen ◽  
Pengfei Liu ◽  
Baosong Xu ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Photoelectron Spectroscopy ◽  
Aqueous Media ◽  
Colloidal Dispersion ◽  
Nitrogen Atmosphere ◽  
Initial Mass ◽  
Core Shell ◽  
Composite Powders ◽  
Transmission Electron ◽  
Novel Method

The present study describes a novel method to improve the dispersibility of silicon nitride powders in aqueous media. Specifically, a new Si3N4@g-C3N4 core–shell composite material was synthesized via annealing the mixture of silicon nitride and melamine under a nitrogen atmosphere using heating method. The effects of various initial mass ratios of Si3N4 and melamine on the structure and dispersibility of the composite were systematically investigated. The results of X-ray photoelectron spectroscopy and transmission electron microscope demonstrated that as-obtained Si3N4@g-C3N4 composite powders possess the core–shell structure, whereas the zeta potential and sedimentation analysis showed that they exhibit good dispersion in aqueous media. Furthermore, the colloidal dispersion of the composite powders is most stable when the initial mass ratio of Si3N4 and melamine is 100:3. The coated g-C3N4 could be completely removed in a cryogenic nitrogen atmosphere. The proposed process is expected to provide novel avenues for the study of dispersion of other inorganic powders.

Preparation and Characterization of Multilayer Graphene by Mechanical Milling and Related Applications for Ceramic Composites

2012 ◽  
Vol 729 ◽  
pp. 252-259 ◽  
Author(s):  
Peter Kun ◽  
Orsolya Tapasztó ◽  
Zsolt Czigány ◽  
Csaba Balázsi
Keyword(s):  
Electron Microscope ◽  
Silicon Nitride ◽  
Mechanical Milling ◽  
Bending Strength ◽  
Ceramic Composites ◽  
Multilayer Graphene ◽  
Graphite Nanoplatelets ◽  
Silicon Nitride Ceramic ◽  
Transmission Electron

As graphene nanomaterials present exceptional mechanical, thermal and electric properties therefore it can be an excellent reinforcement material for ceramic composites. The research of ceramic composites incorporated with carbon-based fillers has focused on carbon nanotubes until now. In this work silicon nitride-based nanocomposites have been prepared with different ammount (1 and 3 wt%) of multilayer graphene (MLG) made by mechanical milling-based method as well as exfoliated graphite nanoplatelets (xGnP) and nanographene platelets (Angstron) in comparison. The morphology and microstructure of the sintered samples were studied by scanning electron microscope and transmission electron microscope. Phase compositions were determined by X-ray diffractometer. The bending strength and elastic modulus of MLG-silicon nitride composites showed enhanced values compared to the other graphene reinforced silicon nitride ceramic composites.

Characterization of microwave-sintered ceramic composites

1993 ◽  
Vol 51 ◽  
pp. 1136-1137
Author(s):  
X. Zhang ◽  
Y. Pan ◽  
T.T. Meek
Keyword(s):  
Matrix Material ◽  
Maximum Output Power ◽  
Ceramic Matrix Composite ◽  
Ceramic Composites ◽  
Processing Technique ◽  
Structure Characterization ◽  
Alumina Powder ◽  
Maximum Output ◽  
Sintered Ceramic

Industrial microwave heating technology has emerged as a new ceramic processing technique. The unique advantages of fast sintering, high density, and improved materials properties makes it superior in certain respects to other processing methods. This work presents the structure characterization of a microwave sintered ceramic matrix composite.Commercial α-alumina powder A-16 (Alcoa) is chosen as the matrix material, β-silicon carbide whiskers (Third Millennium Technologies, Inc.) are used as the reinforcing element. The green samples consisted of 90 vol% Al2O3 powder and 10 vol% ultrasonically-dispersed SiC whiskers. The powder mixture is blended together, and then uniaxially pressed into a cylindrical pellet under a pressure of 230 MPa, which yields a 52% green density. The sintering experiments are carried out using an industry microwave system (Gober, Model S6F) which generates microwave radiation at 2.45 GHz with a maximum output power of 6 kW. The composites are sintered at two different temperatures (1550°C and 1650°C) with various isothermal processing time intervals ranging from 10 to 20 min.

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