Preparation and Properties of BN-SiO2 Composite Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1426-1428 ◽  
Author(s):  
Hua Zhang Zhai ◽  
Hong Nian Cai ◽  
Xiao Zhan Yang ◽  
Jian Bao Li ◽  
Gang Feng Guo ◽  
...  
Keyword(s):  
Hexagonal Boron Nitride ◽  
Secondary Phase ◽  
Silica Content ◽  
Silica Sol ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintered Composite ◽  
Boron Nitride Powder ◽  
Scanning Electron

A series of BN-SiO2 composite ceramics with high relative densities have been fabricated by hot pressing of a mixture of hexagonal boron nitride powder and silica sol. X-ray diffraction (XRD) results show that silica are distributed in the BN matrix as noncrystalline state. Microstructure of as-sintered composite ceramics is observed by scanning electron microscopy (SEM). The influence of the secondary phase on the mechanical properties is studied by varying the silica content from 10 wt% up to 40 wt%. Dielectric properties of composite ceramics are also measured from 1 MHz to 2.0 GHz.

High-performance electrical properties of La-based perovskite ceramics for the functional phase of thick film resistors

2020 ◽  
Author(s):  
Yongcheng Lu ◽  
Yuanxun Li ◽  
Daming Chen ◽  
Rui Peng ◽  
Qinghui Yang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Properties ◽  
Thick Film ◽  
High Performance ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alternative Material ◽  
Perovskite Ceramics ◽  
Scanning Electron

Abstract In order to explore an economical functional phase alternative material for thick film resistors, the crystal structure, microstructure, and electrical properties of (1-x)LSCN + xLCNZ (x = 0.0–1.0) composite ceramics were studied through solid-state reaction experiments. The composite ceramics were characterized by x–ray diffraction, scanning electron microscopy, energy dispersive x–ray spectroscopy, and DC four–probe method. Results suggested that the main phases of LSCN and LCNZ were formed, along with a small part of impurity phases. The addition of LCNZ to LSCN decreased the electrical conductivity and changed the TCR from positive to negative. Zero TCR could be achieved around 0.6 < x < 0.8 and relatively low absolute TCR values could be obtained for the samples of 0.4 ≤ x ≤ 0.8. The ceramic of 0.6LSCN + 0.4LCNZ showed the optimal performances of conductivity = 1923 S/cm, TCR = 379.54 ppm/℃, and relative density = 95.05%.

scholarly journals Phase, microstructure and microwave dielectric properties of Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics

2015 ◽  
Vol 33 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Abdul Manan ◽  
Dil Nawaz Khan ◽  
Atta Ullah ◽  
Arbab Safeer Ahmad
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Secondary Phase ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Scanning Electron

AbstractMg0:95Ni0:05Ti0:98Zr0:02O3 ceramics was prepared via conventional solid-state mixed-oxide route. The phase, microstructure and microwave dielectric properties of the sintered samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vector network analyzer. The microstructure comprised of circular and elongated plate-like grains. The semi quantitative analysis (EDS) of the circular and elongated grains revealed the existence of Mg0:95Ni0:05T2O5 as a secondary phase along with the parent Mg0:95Ni0:05Ti0:98Zr0:02O3 phase, which was consistent with the XRD findings. In the present study, εr ~17.1, Qufo~195855 ± 2550 GHz and τf ~ -46 ppm/K was achieved for the synthesized Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics sintered at 1325 °C for 4 h.

Influence of Copper Concentration on the Structural and Optical Properties of Chemically Deposited CuSbS2 Thin Films

2016 ◽  
Vol 19 (1) ◽  
pp. 015-019 ◽  
Author(s):  
Jebadurai Joy Jeba Vijila ◽  
Kannusamy Mohanraj ◽  
Sethuramachandran Thanikaikarasan ◽  
Ganesan Sivakumar ◽  
Thaiyan Mahalingam ◽  
...  
Keyword(s):  
Thin Films ◽  
Field Emission ◽  
Secondary Phase ◽  
Diffraction Field ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Simple Chemical ◽  
Scanning Electron

Thin films of CuSbS2 have been deposited on ultrasonically cleaned glass substrates using a simple chemical bath deposition technique. Prepared films have been characterized using X-ray diffraction, Field Emission Scanning Electron Microscopy and UV-Vis-NIR spectroscopic techniques, respectively. X-ray diffraction analysis revealed that the prepared films possess polycrystalline in nature with orthorhombic CuSbS2 in addition to secondary phase of monoclinic Cu3SbS3 and cubic Cu12Sb4S13 for different copper concentrations. Field Emission Scanning Electron Spectroscopic analysis showed that the prepared films possess spherical shaped grains with irregular shaped clusters. Optical absorption analysis showed that the prepared films possess band gap value in the range between 1.7 and 2.4 eV.

Preparation and Characterisation of Amorphous Silica from Alkali Wastewater Produced in Manufacturing Process of ZrOCl2

2011 ◽  
Vol 194-196 ◽  
pp. 2164-2168 ◽  
Author(s):  
Bai Kun Wang ◽  
Hao Ding ◽  
Yun Xing Zheng ◽  
Ning Liang
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Amorphous Silica ◽  
Manufacturing Process ◽  
Zirconium Oxychloride ◽  
Silica Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The amorphous silica was prepared from the alkali wastewater rich in Na2O•nSiO2 produced in manufacturing process of zirconium oxychloride (ZrOCl2). The composition and microstructure of amorphous silica were studied by X-ray diffraction, X-ray fluorescence and scanning electron microscope, respectively. The results showed that the amorphous silica was mainly composed of uncrystallized substance, and the silica content was 96.4%. Its whiteness was 97.5% and the particle size was between 100nm and 200nm without agglomeration. The specific surface area of the amorphous silica was 531.9 m2/g, and its pore volume and diameter were 0.945 cm3/g and 4.94 nm, respectively.

Effect of the additive content on the sintering of pre-sintered Si3N4 composite.

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3103-3111
Author(s):  
Angel Leon-Geronimo ◽  
Quetzalmaflor Miranda-Hernandez ◽  
Ignacio Figueroa-Vargas ◽  
José Lemus-Ruiz
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Precipitation Mechanism ◽  
X Ray ◽  
Additive Content ◽  
Scanning Electron

AbstractSintering of Si3N4 compounds requires additives that promote densification through the dissolution-precipitation mechanism in liquid phase sintering. The sintering of the Si3N4 with the SiO2-Y2O3-Al2O3 system has been extensively studied. Nevertheless, because SiO2 depends on the natural amount on the Si3N4 surface, little has been studied about SiO2 control. A pre-sintering treatment can increase the content of SiO2 through controlled oxidation of Si3N4. In this work the effect of the additive content on the densification of Si3N4 composite ceramics was evaluated. For this purpose, powder mixtures of Si3N4, Y2O3 and Al2O3 were prepared. The Y2O3 and Al2O3 ratio were modified in percentages of 4, 8 and 12% by weight. The mixtures were compacted and pre-sintered at 1300°C for 1 hour. Then, these were sintered at 1450°C for two hours. The samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that during pre-sintering, the Y5(SiO4)3N phase is formed; then, it's subsequently oxidized at the sintering stage. A second phase identified as Y3Al5O12 was found in samples with higher proportions of Al2O3. Composition and quantity of the observed phases depend of Y2O3 and Al2O3 proportion in the added additive.

Preparation and Dielectric Properties of Si3N4/BN(CB) Composite Ceramic

2016 ◽  
Vol 35 (5) ◽  
pp. 523-529
Author(s):  
Xiao Weiling ◽  
Xiao Peng ◽  
Luo Heng ◽  
Zhou Wei ◽  
Li Yang
Keyword(s):  
Electron Microscopy ◽  
Electromagnetic Wave ◽  
Composite Ceramic ◽  
Mass Content ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Carbon ◽  
Pass Through ◽  
Scanning Electron

AbstractSi3N4/nano-carbon black (CB) composite ceramics with boron nitride (BN) as interphase were fabricated by gelcasting. The results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that the structures of BN interphase and BN coated CB were formed and were uniform distributed in the Si3N4 ceramic. The permittivity (ε′ε″) of BN-coated CB was obviously lower than that of the pure CB, and the impedance of the BN-coated CB particles was close to the Z0 (Z0 = 1, Z0 is impedance under vacuum) compared with that of the CB particles; therefore, electromagnetic wave can enter into the BN-coated CB particles and be dissipated due to the high conductivity of CB particles. When incorporating the BN(CB) into Si3N4 substrate, the electromagnetic wave can pass through Si3N4/nano-CB composite ceramics easily and be absorbed by CB, so the tgδ of the composite ceramic increased as the mass content of BN(CB) increased. The tgδ of the composite ceramic was about 0.43 when the content of BN(CB) increased to 15 wt%.

Development and Evaluation of Mechanical Properties of Al/Ilmenite Nanocomposite

2014 ◽  
Vol 704 ◽  
pp. 32-38
Author(s):  
Lanka Rasidhar ◽  
A. Rama Krishna ◽  
Ch. Srinivasa Rao ◽  
K. Vijaya Lakshmi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Secondary Phase ◽  
Stir Casting ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron

In the present investigation, microstructure and mechanical properties of nanocomposites fabricated via stir casting were evaluated. The composites were based on Al (99.7) reinforced with ilmenite nanoparticles. The characterization of the nanoparticles and nanocomposites was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) facilities. Microstructure of specimens show that reasonable distribution of FeTiO3 nanoparticles in the matrix, secondary phase FeAl3 observed in the microstructure. Ultimate tensile strength and compression tests were carried out in order to identify the mechanical properties. The hardness of the composites is enhanced with the addition of nanoparticles. The optimum value for ultimate tensile and compression strength are obtained with the addition of 3 % ilmenite nanoparticles. Ductile fracture in tensile fractured samples was observed by fractrography examination.

scholarly journals Synthesis of h-BN by the Combustion of B/KNO3/Octogen Mixture under Nitrogen Atmosphere

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Song-qi Hu ◽  
Yin Wang ◽  
Lin-lin Liu
Keyword(s):  
High Purity ◽  
Photoelectron Spectroscopy ◽  
Hexagonal Boron Nitride ◽  
Nitrogen Atmosphere ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistance To Oxidation ◽  
Scanning Electron ◽  
Main Impurity

Hexagonal boron nitride (h-BN) powders were fabricated by the combustion synthesis with B/KNO3/HMX (octogen) mixtures as reactants. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to investigate the phase composition and the chemical composition of the products, respectively. The morphology and resistance to oxidation were studied by scanning electron microscopy (SEM) and thermogravimetry (TGA), respectively. The characterization results showed that the h-BN which was produced through this method has high purity and exhibits excellent resistance to oxidation. The purity of h-BN is improved with the increasing content of HMX in reactants with boron carbide (B4C) and boron oxide (B2O3) as main impurity, but conversely, the yields are obviously decreased. Taking the comprehensive consideration of the purity and the yields together, the optimal molar ratio of B/KNO3/HMX is 10 : 1 : 4. In addition, the experimental results indicated that the crystalline grain size grows with the increasing content of HMX. The method explored in this study does not need expensive processing facilities and equipment, which is a preferable approach for the laboratory to prepare h-BN of high purity.

Grinding Characteristics and Removal Mechanisms of LaPO4/Al2O3 Micro-Nano Composite Ceramics

2011 ◽  
Vol 306-307 ◽  
pp. 774-777
Author(s):  
Wen Lai Zhang ◽  
Xin Wang ◽  
Chao Hong Liu ◽  
Gui Jun Jiang ◽  
Qiu Ju Zheng
Keyword(s):  
Weak Interface ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Nano Composite ◽  
X Ray ◽  
Transmission Electron ◽  
Main Fracture ◽  
Core Shell Structure ◽  
Grinding Machine ◽  
Scanning Electron

In this paper, the prepared LaPO4/Al2O3composite ceramics were ground by the surface grinding machine. The phase composition and morphology of the coated powders as well as the microstructure of grinding surface of the ceramics were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM), respectively. The results show that the coated powders have a distinct core-shell structure which has a great effect on material’s removal approaches. The main fracture mode is caused by intragranular fracture of layered LaPO4rather than the weak interface. Besides, the primary grinding removal mechanism of LaPO4/Al2O3composite ceramics mainly rise from cracks propagating along the interlayer of LaPO4.

Preparation of TiB2-TiC Intermetallic Phase via Mechanical Alloying

2011 ◽  
Vol 403-408 ◽  
pp. 634-639 ◽  
Author(s):  
Ping Luo ◽  
Shi Jie Dong ◽  
Qiu Yue Shi ◽  
Zhang Qiang Mei
Keyword(s):  
Mechanical Alloying ◽  
Intermetallic Phase ◽  
Protective Atmosphere ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
X Ray ◽  
Hot Pressing Sintering ◽  
Morphology Characteristics ◽  
Scanning Electron

TiB2-TiC intermediate metal powder was fabricated via mechanical alloying (MA) processing, and the phase formation and powder morphology characteristics were studied by using X-ray diffraction（XRD）, scanning electron microscopy (SEM), differential thermal analysis (DTA). Starting materials were milled at ambient temperature in argon protective atmosphere. Prepared intermetallic phase of TiB2-TiC included, Ti3B4、Ti2B5、TiC0.06. Used milled powders prepare TiB2-TiC composition via two-way vacuum hot pressing sintering furnace not only decrease the time of preparation, but also reduce temperature of reaction, because of the preactivation reaction during MA promote the reactions. Therefore, this process will promote TiB2-TiC composite ceramics in engineering applications.

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