bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Different Oxygen Flow Rate on Physical Properties of ITO Thin Films Deposited by Ion-Assistant Electron Beam Evaporation
Authors: Qiu Yang , Meng De Yi , Chen Yu Feng , Zu Chen Kui
Published: March 2014

Tin doped indium oxide (ITO) thin films were prepared on IR glass substrates at different oxygen flow rate by ion-assisted electron beam evaporation method, high purity ITO particles (In2O3: SnO2 = 9:1 Wt%) were used as source material. Properties such as microstructure, morphology and mechanical properties were investigated by X-ray diffractometer, SEM and scratch tester, respectively. Meanwhile, lattice constant a, crystal grain size and residual stress situation of films as-deposited were calculated and discussed in detail. The results indicated that all of the films as-deposited were polycrystalline and represented [111] preferential orientation. With the increasing of the oxygen flow rate, grain size and surface roughness of films as-deposited decreased, and inner stress remained in film increased. There were two types of failure mode occurred in ITO films according to different stress situation. Relative high level of residual stress improved the mechanical properties of ITO films in a certain extent.
Acid-Washing Behavior of TiB2/MgAl2O4/MgO Composite Powders
Authors: Wang Ming Yuan , Zhao Fang , Li Jun Shou , Li Su , Wu Xiao Juan
Published: March 2014

Using TiO2B2O3 powders as oxidizer,AlMg powders as reducer,the TiB2 multiphase ceramic are preparated with SHS, and analysed with SEM and XRD.The effect of HCl, H3PO4 to pickling of TiB2-based multiphase ceramics is explored by SEM and XRD analysis. Research suggests that: the main ingredients of TiB2-based multiphase ceramics is TiB2, MgO and MgAl2O4 three phases, few of reaction residual objects and impurities also exists; the multiphase ceramics is forming by many of hexagonal crystal type products and small particles reunion, hexagonal crystal type product is TiB2, small particles may be MgO, MgAl2O4 and other impurities product; MgO can be effectively washed by HCl and H3PO4 , but TiB2 and MgAl2O4 invalid. At room temperature, 30% HCl pickling has the best effect, the concentration of TiB2(ω) is up to 59.3%; the higher of the concentration, the better of acid-effect; In the pickling process, as the temperature rises, the concentration of TiB2 grows, but the temperature should not be too high. When temperature reach 75 °C, HCl volatilizes too quickly and inefficiently. At room temperature, 20% H3PO4 has the best pickling effect, the concentration of TiB2(ω) is up to 52.6%, but the best pickling effect is not well with concentration increasing; as the temperature increasing, purity of TiB2 is also increased; At 70°C, the concentration of TiB2(ω) after H3PO4 pickling is up to 61.9%, refine effect is good.
Influence of Reaction Time on Properties of BaTiO3 Coated Ni Nanoparticles by a Novel Sol-Precipitation Method
Authors: Hao Ya Nan , Wang Xiao Hui , Li Long Tu
Published: March 2014

Uniform BaTiO3 polycrystalline coating layer on Ni nanoparticles is achieved by a novel sol-precipitation method. The Fourier transform infrared spectra (FT-IR) of the coated samples inhibit that there is typical Ba-O and Ti-O bond for crystalline BaTiO3.The influence of reaction time on the properties of the coated samples is investigated. It is found that the coating layer contains less BaCO3 impurity and crystallizes more completely along with the increase of the reaction time. Moreover, the anti-oxidation properties of these samples are significantly improved.
The Effect of Sucrose on Adsorption Properties of Hexagonal Boron Nitride Powders
Authors: Zhang Ning , Fu Ting Ting , Yang Fei Yi , Kan Hong Min , Wang Xiao Yang , Long Hai Bo
Published: March 2014

In the work reported here, boron source is borax, carbon source is sucrose and the nitrogen source is urea, polymer-network method is applied to prepare the hexagonal boron nitride (h-BN) precursor, and then synthesized the h-BN powders with high purity and high surface area. As the sucrose content is fixed, we study the effect of carbonization temperature on phase composition and adsorption properties of h-BN powders. As the carbonization temperature is fixed, the effect of sucrose content on phase composition and adsorption properties of h-BN powders are studied. The results show that the optimum carbonization temperature is 220°C, and when the sucrose content reach 17.45wt.%, the h-BN powders showed the best adsorption properties.
Effect of pH Value of the Broth on the Gelled Microspheres Containing Zirconium Prepared by Internal Gelation Process
Authors: Gao Yong , Ma Jing Tao , Zhao Xing Yu , Hao Shao Chang , Deng Chang Sheng
Published: March 2014

The internal gelation process was used to produce gel microspheres containing Zr. The effect of the broth composition particularly pH value on the stability of the broth and morphology of the dried spheres was investigated. The results indicated that the stability of the broth at room temperature increased with the decrease of the pH of the broth. When the pH of the broth was in the range of 1 to 2 the spheres obtained had good sphericity and uniform size and at pH of 1.35 the spheres were transparent.
Preparation of Porous Carbon Preform by Casting Camphene Based Charcoal Slurry
Authors: Hu Chuan Qi , Wang Chun Peng , Liang Hai Long , Huo Yan Li , Huang Xiao Ting , Tang Jie
Published: March 2014

This paper describes the process of fabricating porous carbon preform by casting the camphene based charcoal slurry. Five kinds of slurry with different solid content varied from 20vol% to 40vol% has been prepared, we have studied the rheological behavior of slurries and the sublimation behavior of casted bodies. Porous carbon preform with negligible linear shrinkage (<0.6%), high porosity (>67vol%) and interconnected pore structure has prepared.
The Effect of TiC on the Liquid Phase Sintering of SiC Ceramics with Al2O3 and Y2O3 Additives
Authors: Liang Han Qin , Yao Xiu Min , Zhang Hui , Liu Xue Jian , Huang Zheng Ren
Published: March 2014

Low fracture toughness of SiC ceramics limits their applications for the low reliability. Inclusion of second ceramic phase improves the toughness of SiC ceramics. In this presentation, SiC ceramics with 5wt% TiC was pressureless liquid phase sintered (LPS) with the additives of Al2O3 and Y2O3 to ~98% theoretical density at the temperature of 1920 °C for 1 hour. The TiC grains were well distributed and good for the uniform distribution of the liquid phase YAG in the SiC matrix, which resulted in the homogeneous microstructure with fine SiC grains. The existence of TiC benefited the formation of elongated α-SiC, which favored the bridging and deflection of cracks so that the fracture toughness was improved to some extent. Because the amount of TiC was so small that the inherent properties of SiC was not degraded. The flexural strength and Vickers hardness maintained similar with the LPS SiC without TiC. The phase compositions detected in the sample were SiC, YAG and TiC. And no solid-solution of SiC and TiC was revealed by the mapping of EDS.
Fabrication of Carbon Nanofiber and Silicon Carbonitride Ceramic Nanomposites by In Situ Growth during Ceramic Formation
Authors: Liu Meng Ying , Li Ya Li , Qu Sheng Xiang , Han Shuai Shuai , Wang Si Hui
Published: March 2014

Carbon nanofiber (CNF) and silicon carbonitride (SiCN) ceramic nanocomposites (SiCN/CNF) are fabricated by in-situ growth of CNFs in SiCN ceramics during ceramic transformation of polymeric precursors of polysilazanes (PSZ). Metal catalyst precursors are mixed into the polysilazane liquid forming metal particles from decomposition under heating during the pyrolysis. At certain temperatures, ethylene was introduced as a carbon source to induce the growth of CNFs over the metal particles in the ceramic body followed by heating to higher temperatures to complete the pyrolysis. In this way, bulk nanocomposites of SiCN/CNF are obtained as crack-free bodies although some pores are left in the sample. Scanning electron microscopy (SEM) analysis performed on the cross-section of nanocomposites revealed the distribution of needle-like nanofibers of diameter ~ 200 nm and exposed length of ~ 2 μm. The CNFs exhibited the unique multiscale nanostructure in micron hollow tubes with branched nanofiber walls. Energy dispersive X-ray spectrometer (EDX) detected carbon as the major element from the nanofibers confirming the formation of carbon nanofibers. Moreover, clusters of nanoparticles are formed on the ceramic surface from carbon depositions. The in-situ growth of CNFs in SiCN ceramics provides a one-step process potentially to be developed for fabrication of structural and functional SiCN/CNF nanocomposites.
Influence of CeO2 Additive on the Phase Transformations of Zirconia from Zircon Ore by Carbothermal Reduction Process
Authors: Wang Teng Yu , Xu You Guo , Huang Zhao Hui , Fang Ming Hao , Liu Yan Gai , Wu Xiao Wen , Yin Li , Liu Bao Lin , Hu Xiao Zhi
Published: March 2014

This paper mainly discusses the influences of heating temperatures and CeO2additive contents on the phase transformations of zirconia from zircon ore by carbothermal reduction. The phase transformations of zirconia from zircon ore by carbothermal reduction were monitored by X-ray diffraction. The microstructure of the product was characterized by scanning electron microscopy. The results show that without adding CeO2, the optimized heating temperature of zircon carbothermal reduction was 1600 °C and the main phases of the product were m-ZrO2, ZrC and β-SiC, t-ZrO2; After adding CeO2, the main phase of the products consists of t-ZrO2, m-ZrO2, ZrC and β-SiC when the heating temperature is 1600 °C. CeO2additive can be introduced into zirconia lattice and can cause it to form cerium stabilized zirconia. Zirconia in the product would be turned into partially stabilized zirconia with cerium addition from 5 wt% to 20 wt%. However, the form of zirconia in the product is not changed greatly with the amount of CeO2additive increase.
Optimal Preparation and Characterization of Sputtered Y2O3 Films on Sapphire Substrates
Authors: Wang Gui Gen , Qian Hong Liang , Li Qing Tao , Qin Guo Shuang , Luo Lin
Published: March 2014

Normal 0 7.8 磅 0 2 false false false MicrosoftInternetExplorer4 It is necessary to prepare compressive films on sapphire window for preventing its high-temperature failure. In this study, the yttrium oxide (Y2O3) thin films were deposited on the sapphire substrates by RF reactive magnetron sputtering with varying sputtering pressure. The as-deposited Y2O3films were also annealed. The composition, structure, refractive index and mechanical properties of the films were systematically analyzed by XPS, XRD, ellipsometry and nanoindention method, respectively. The influences of sputtering pressure on the deposition velocity and the refractive index were investigated. It can obtain desirable Y2O3thin films for the preparation conditions (sputtering pressure: 10Pa, substrate temperature: 500°C, RF power: 200W) after annealing in O2at 500°C for 1h. The refractive index and hardness both have the maximum value (1.8337 and 3.98 GPa), respectively. The elastic module has the minimum value (109.24 GPa). It is promising for the Y2O3film as the underlayer of protective coating of sapphire windows.  st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:普通表格; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0pt 5.4pt 0pt 5.4pt; mso-para-margin:0pt; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}
Si/SiC-Based Layer Deposited on Boron Carbide Particles via CVD
Authors: Xu Yu Feng , Ru Hong Qiang , Yue Xin Yan
Published: March 2014

The application of B4C as structural materials has been restricted largely because of its poor sinter-ability. Compared with pressure-less and hot pressing methods, sintering the B4C via the reaction-bonded boron carbide (RBBC) can to great extent circumvent such problem, which can even be conducted at low temperature, when Si/Si-based alloy was used as binding phase. However molten Si/Si-based alloy infiltrated into performs of bare B4C powders can strongly react with and significantly consume B4C particles based on molten infiltration reaction method. The present study aims to encapsulate B4C particles with a protective layer to block off its contact with molten Si/ Si-based alloy via chemical vapor deposition (CVD) method in CH3SiCl3(MTS)-H2-Ar system at low temperature (900-1100 °C) under atmospheric pressure. The phase composition and surface morphology of encapsulated B4C particles were studied using X-ray diffraction (XRD) , scanning electron microscopy (SEM) plus energy dispersive spectrometer (EDS), respectively. It was found that the deposition temperatures have a significant effect on microstructure and composition of deposited coating. The studies on surface morphology revealed that spine-like crystals, nodular growth, island structure and whiskers can be deposited onto the surface of boron carbide particles. When deposited at 900-1000 °C,the coatings is Si + SiC co-deposition, while pure SiC coatings form only at as high deposition temperature at 1050 °Cand 1100 °C.
The Formation and its Related Mechanism of Lu2Ti2O7 Octahedrons Grown from Molten Salt
Authors: Yan Kang Hua , Zhao Chuang Feng , Yang Zhi Wei , Liu Dong Yu , Li Bao Rang
Published: March 2014

Lu2Ti2O7octahedrons were synthesized by molten salt synthesis (MSS) through selecting appropriate source materials and controlling proper external conditions. The phase constituents and microstructure morphologies of as-product were characterized by X-ray powder diffraction, Energy Dispersive Spectrometer, Field Emission Scanning Electron Microscopy and High-resolution Transmission Electron Microscopy. According to the experimental results, the detailed microstructure and growth mechanism of Lu2Ti2O7octahedron have been analyzed. The presented results in this paper may benefit to a deeper understanding of the fundamental physical and chemical processes of MSS methods.
Oxidation Behavior of Amorphous Nano-Si3N4 Powders
Authors: Wen Jiang Bo , Huang Sheng , Wang Hong Jie
Published: March 2014

The traditional method preparing Si3N4/Si2N2O composite ceramic is to sinter α-Si3N4 powder with additives at relatively high temperatures. But the intergranular phase transformed from the sintering additives can degrade the high-temperature mechanical behavior. Amorphous nanoSi3N4 is used to fabricate Si3N4/Si2N2O composite ceramic by its oxidation and nitridation without sintering additives at low temperatures. Thus, it is essential to study the oxidation behavior and mechanism of amorphous nanoSi3N4. Amorphous nanoSi3N4 powders were oxidized in different atmospheres, at varying temperatures and for various different length of time. The oxidation process and products was analyzed by means of XRD, TGA and FTIR. The results showed that amorphous nanoSi3N4 could be oxidized into SiO2 from 600°C to 1300°C. Below 1300°C, the oxidation became serious as the temperature increased. Besides, the longer the oxidation time and the lager the ratio of O2/N2 partial pressure was, the deeper the oxidation level was. When the temperature was above 1300°C, amorphous nanoSi3N4 was completely oxidized into SiO2.
Properties and Processing of Porous Si3N4 Ceramics
Authors: Zhao Xiao Tong , Wang Hai Long , Shang Wei , Chen Jian Bao , Xu Hong Liang , Lu Hong Xia , Chen De Liang , Fan Bing Bing , Zhang Rui
Published: March 2014

Porous silicon nitride (Si3N4) ceramics green were prepared by sol-gel and freeze drying processing. Al2O3and MgO were selected as sintering additives. Porous Si3N4ceramics were sintered at 1200~1300 °C. The porosity of porous Si3N4ceramics reached 60~80%, the pore size of porous Si3N4ceramics dried by freeze drying is less than 5μm. Two kinds of pores were formed, including open pores with pore size of 1~5μm and closed pores pore size with the nanometer level. The compression strength of porous Si3N4ceramics was 15~25MPa. Thermal conductivity of porous Si3N4ceramics was 0.08-0.1 W/m·K.
Preparation of Nano ZnO Particles by Microwave Assisted Hydrothermal Method and its Toxicity to Microalgae
Authors: Yu Hong Ying , Dong Zhi Jiang , Chen Zhi Qin , Luo Shan Shan
Published: March 2014

In this paper, nanocrystalline ZnO particles were prepared feasibly by microwave assisted hydrothermal method with Zinc nitrate and NaOH as start materials. XRD results show the ZnO was crystallized well. The as-received powders are hexagonal platelets of about 20-100 nm in diameter. Toxicity experiments using wastewater microalgae (Chlorella sp.) revealed that the toxicity of ZnO is strongly related with the Zinc ions concentration in water.
Preparation and Properties of β-SiAlON-cBN Composites Using Y2O3, B2O3 and Al as Additives
Authors: He Chao , Shi Xiao Fei , Yue Xin Yan , Wang Jiang Jun , Ru Hong Qiang
Published: March 2014

SiAlON-cBN composites with different contents of cBN were consolidated by spark plasma sintering (SPS) at 1450°C using Y2O3, B2O3 and Al as additives. The effect of cBN content on the density, phase compositions, microstructures and mechanical properties of β-SiAlON-cBN composites was investigated. With increasing the cBN content, the density and hardness of β-SiAlON-cBN composites decreased. Fracture toughness could increase thanks to the crack deflection resulted from the cBN particles. For β-SiAlON-10 wt% cBN composites, the optimum hardness and highest relative density were 13 GPa and 96.4 %, respectively. For β-SiAlON-40 wt% cBN composites, the highest fracture toughness was KIC = 5.3 MPa∙m1/2.
Fabrication of Macroporous SiCN Ceramics from Mixed Polysilazanes
Authors: Su Dong , Yan Xiao , Hou Feng
Published: March 2014

Macroporous polymer-derived SiCN ceramics are fabricated directly by mixing polysilazane precursors followed with crosslinking and pyrolysis. Two kinds of polysilazanes namely polyvinylsilazane and polyhydrosilazane are mixed, crosslinked by 2, 2-Azo-bis-isobutyronitrile to form resins before pyrolyzed to form ceramics in argon flow at 1000°C. The density of the SiCN ceramic is 1.65 g/cm3 with corresponding porosity of 30 % compared to dense SiCN ceramics. SEM images show that the ceramics possess high porosity and homogeneous honeycomb-like macropores of ~2 μm. The porous SiCN exhibits good mechanical property with Vicker hardness of 11-13 GPa under a load of 0.2 kg.
Mechanical Properties of Cf/SiC-ZrB2 Composites
Authors: Zhou Chang Ling , Wang Yan Yan , Wang Chong Hai , Liu Riu Xiang
Published: March 2014

Cf/SiC-ZrB2 composites were fabricated by chemical vapor infiltration and precursor infiltration pyrolysis. Specimens were then tested for mechanical properties , thermo-physical properties and microstructure. Results show flexural strength, tensile strength and compressive strength reach 430MPa,120 MPa and 365 Mpa, respectively. The mechanical properties at high temperature were tested. And the fractograph and microstructure of composites were analysized.
Effect of Molding Process on Properties of Laminated ZrB2-SiC-Cg Ultra High Temperature Ceramics
Authors: Wei Chun Cheng , Zhang Xing Hong , Han Wen Bo , Hu Ping
Published: March 2014

Laminated ZrB2-SiC-Cg ceramics were successfully prepared by tape casting - dipping and tape casting - stacking respectively. The effect of different molding process on the mechanical properties of materials was investigated. The microstructure and fracture behavior were characterized as well. The flexural strength, fracture toughness and fracture work of laminated ZrB2-SiC-Cg ceramics prepared by tape casting-stacking were 427 MPa, 11.3 MPa·m1/2, 415 J/m2, respectively. The thickness of ZrB2-SiC layers was about 250 μm, and the thickness of graphite layers was about 25 μm. As a comparison, Laminated ZrB2-SiC-Cg ceramics prepared by tape casting - dipping showed non-uniform thickness of the ZrB2-SiC layers and graphite layers. And the flexural strength, fracture toughness and fracture work of laminated ZrB2-SiC-Cg ceramics prepared by tape casting-dipping were 252 MPa, 5.7 MPa·m1/2, 104 J/m2, respectively. The improvement on the mechanical properties of laminated ZrB2-SiC-Cg ceramics prepared by tape casting - stacking was attributed to the uniform graphite layer and ZrB2-SiC layer and the reducing amount of graphite infiltrated into ZrB2-SiC matrix layer.
Microwave-Assisted Synthesis and Gas-Sensing Performance of Hollow-Spherical WO3 Nanocrystals
Authors: Yin Li , Shao Gang , Fan Bing Bing , Chen De Liang , Zhang Rui
Published: March 2014

Hollow-spherical WO3 nanocrystals were obtained by calcining an organic-inorganic W-C precursor containing C and W in a microwave oven or in a conventional muffle furnace, and the W-C precursor hybrid precursor was synthesized via a hydrothermal method. The samples were characterized by XRD, TG-DTA, FTIR and SEM. The morphologies of the WO3 samples obtained by conventionally heating (C-WO3) and microwave-assisted heating (M-WO3) were compared. The average diameter and shell thickness of C-WO3 hollow spheres is about 450 and 200 nm, respectively. The average diameter and shell thickness of M-WO3 hollow spheres is about 500 and 50 nm, respectively. The M-WO3 has a loose and multilayered shell, and their nanoparticles are smaller than those of C-WO3. The improved structure of M-WO3 is due to shorter heating time and the unique heating style in a microwave oven. The gas-sensing performances of the WO3 sensors were investigated. The M-WO3 sensor has better response to ethanol vapors than the C-WO3.
Ti2AlC/TiAl Matrix Intermetallic Compound Prepared by In Situ Hot Pressing
Authors: Ai Tao Tao , Wang Fen , Yang Chen Hui
Published: March 2014

As the new structural material, TiAl intermetallic compound has great potential application in aerospace engine, energy and automotive fields. But the bottleneck problems including poor room temperature ductility and high-temperature oxidation resistance limit its application. Ti2AlC possesses an unusual combination of the merits of both metals and ceramics, which is considered the best reinforcement for TiAl intermetallic compound. In the present work, Ti2AlC/TiAl matrix intermetallic compound was successfully fabricated by in situ hot pressing method from the mixture of Ti/Al/TiC. The phase transitions were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The microstructure of the product was studied by scanning electron microscopy (SEM). Ti reacted with Al liquids to form Ti-Al intermetallics below 900 °C firstly. With increasing temperature (above 900 °C), a part of TiAl intermetallics reacted with TiC to form Ti2AlC reinforcement. The as-sintered product presented dense and typical lamellar structure. The in-situ synthesized fine Ti2AlC contributed to improve the strength of TiAl matrix intermetallic compound.
Properties of B4C-Based Composite with Layered Structure
Authors: Li Zhen Nan , Fan Si Yang , Yue Xin Yan , Sun Zhao Bin , Wang Jian Jun , Ru Hong Qiang
Published: March 2014

A three-layer material based on B4C/Al, B4C/TiB2 and B4C composites had been successfully prepared. The microstructures and properties of B4C/Al-B4C/TiB2-B4C composite were investigated in detail. The three-layer porous preform was first prepared by hot pressing. Then the three-layer composite was fabricated by infiltrating aluminum into the porous preform in vacuum. The three-layer B4C/Al-B4C/TiB2-B4C composite showed good interfacial bonding. When using the B4C ceramics layer as the load-bearing surface, the flexural strength, fracture toughness and Vickers hardness of the composite were 230 MPa, 3.4 MPa·m1/2 and 38 GPa, respectively.
Fabrication and Ablation Behavior of Plasma Sprayed ZrC-W Composite Coatings
Authors: Lu Dan , Niu Ya Ran , Ge Xue Lian , Zheng Xue Bing , Chen Guang
Published: March 2014

In this work, atmospheric plasma spray (APS) technology was applied to fabricate ZrC-W composite coatings. The microstructure of the composite coatings was characterized. The influence of W content on the ablation-resistant and thermal shock properties of ZrC-W composite coatings was evaluated using a plasma flame. The results show that the ZrC-W composite coatings had typically lamellar microstructure, which was mainly made up of cubic ZrC, cubic W and a small amount of tetragonal ZrO2. The ZrC-W coatings had improved ablation resistant and thermal shock properties compared with those of the pure ZrC coating. It was supposed that the improved density, thermal conductivity and toughness of the composite coatings contributed to this phenomenon.
Effect of Composite Sintering Aids on the Thermal and Mechanical Properties of Hot-Pressed Aluminum Nitride
Authors: Fu Jun Yu , Wu Shang Hua , Cheng Yan Ling , Fu Chang Lu , Wu Ruo Jun , Lu Zhong Yong
Published: March 2014

The aim of this work was to determine the effect of composite additives on the thermal and mechanical properties of aluminum nitride (AlN) in detail. The composite system has not been studied in depth before. The hot-pressed AlN was prepared with Y2O3-Dy2O3-YF3 and Y2O3-Dy2O3-CaO as the composite sintering additives. As the result, the thermal conductivities for the sintered body with two composite additives were 171 W/m.K and 152 W/m.K, respectively. The fracture toughness values calculated by the Evans & Clarkes’s equation for both of the samples were 2.34±0.09 MPa.m1/2and 2.63±0.13 MPa.m1/2 at 10 kg load. The toughness difference is the result of comprehensive effect of the grain size, the properties of the boundary phase, its distribution, and also the interactions between different phases.
Effect of Silicon Compounds on the Properties of Pressureless Sintered Aluminum Nitride
Authors: Fu Chang Lu , Wu Shang Hua , Cheng Yan Ling , Fu Jun Yu , Wu Ruo Jun , Lu Zhong Yong
Published: March 2014

In this paper, the aluminum nitride (AlN) was fabricated by pressureless sintering with YF3 and various silicon compounds as the sintering aids. The phase, microstructure, density and thermal conductivity were characterized by XRD, SEM and laser thermal diffusivity method. The sample densities were detected varied from 3.17 to 3.30g/cm3 and room-temperature thermal conductivity varied from 196 to 233 W/m·K. Samples sintered with YF3 additives have the highest thermal conductivity. The sintering aids with SiO2, Si3N4 and SiC would decrease the density and the thermal conductivity obviously, and also change the fracture mode from the intergranular to transgranular , which is a key for the toughness of the AlN substrate.
Effect of CNTs on Mechanical Properties of SiCp/Cu Composites
Authors: Wang Chen Yang , Fan Bing Bing , Sun Bing , Wang Bin Bin , Li Wen , Chen Hao , Pian Xiao Xuan , Zhao Biao , Zhang Rui
Published: March 2014

SiCp/Cu composites were prepared by vacuum hot-pressing at 770°C for 1.5 h under the pressure of 30MPa. The composites were enhanced by CNTs with different volume fractions from 0 vol. % to 4 vol. %. Three-step approach wrapping process was introduced to prepare composite powders. XRD and SEM techniques were used to characterize the samples. It is found that the core-shell structure composed of SiC core and Cu shell was formed in the composite particles. Optimized volume fraction of CNTs is 1 vol. %. Minimum Porosity and maximum Hardness is about 0.84% and 2.31GPa, respectively. But maximum Flexural strength was measured as 248MPa for samples containing 2 vol. % CNTs. Flexural strength was improved by the bridge effect caused by the increased CNTs.
Preparation of Hollow Silica Microspheres with Nanoporous Shells by Soft Template Method
Authors: Sui Xue Ye , Xu Jie , Wang Chong Hai , Zhou Chang Ling , Liu Rui Xiang
Published: March 2014

A kind of new hollow silica microspheres were proposed in experiment, which are fabricatted by a fast hydrolysis and condensation of tetraethyl orthosilicate taking place around multi-lamellar octylamine vesicles. The morphology of the vesicles is then fixed by a quick gelation process, resulting in hollow organo-silica spheres. After the removal of the template by calcination, nanopores are formed in the hollow shells. The results show that the synthesized hollow silica microspheres have smooth surface and dispersed well£®There are bimodal nanopores in the hollow silica microspheres, with a diameter of 2.1 nm and 0.62nm for the mesopores and micropores respectively, giving a specific surface area of 1123m2/g and a pore volume of 0.6291mL/g£®
Structure and Properties of Irradiation Crosslinked UHMWPE
Authors: Lin Han , Dong Li Min , Wang Chen , Liang Tong Xiang , Tian Jie Mo
Published: March 2014

Irradiation crosslinking is one of the most important methods to modify UHMWPE, it can effectively improve the hardness, creep resistance and abrasion resistance of this material. In order to eliminate free radical, increase material strength, abrasion resistance and fatigue resistance of creep, this study uses Co60-γ to modify UHMWPE under vacuum atmosphere, with the irradiation dose of 30, 60, 90, 120 Kgy respectively. Its mechanical properties, microstructure, degree of crosslinking and crystallinity are analyzed, the results show that the modified UHMWPEs impact strength decreased, elongation basically remain unchanged, tensile fracture strength and tensile yield strength increased.
Effects of Microwave Sintering Time on Microstructure, Dielectric, Ferroelectric Properties of Barium Zirconate Titanate Ceramics
Authors: Cai Wei , Fu Chun Lin , Chen Gang , Deng Xiao Ling , Liu Kai Hua
Published: March 2014

Barium zirconate titanate ceramics were prepared by microwave sintering. Effects of microwave sintering time at 2.5kW on microstructure, dielectric and ferroelectric properties of barium zirconate titanate ceramics have been investigated. The result shows that the ceramic samples sintered at 2.5kW for 15~30min are single phase perovskite structure and there is no secondary phase observed. The degree of crystallinity increases with the increase of microwave sintering time. As the microwave sintering time increases, barium zirconate titanate ceramics become more uniform and the grain size increases. The Curie temperature of the samples sintered at 2.5kW for 15min, 20min and 30min is-20°C, -10°C and-15°C, respectively. As the microwave sintering time increases, the dielectric constant of barium zirconate titanate ceramics decreases initially and then increases, and the dielectric loss decreases. Moreover, the remnant polarization of the sample increases initially and then decreases, and the coercive electric field decreases as the microwave sintering time increases.
Electrical and Physical Properties of Lead-Free (Na0.5K0.5)NbO3- Bi0.5(Na0.90K0.10)0.5TiO3 Ceramics
Authors: Wang Chun Huy
Published: March 2014

Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3Bi0.5(Na0.90K0.10)0.5TiO3 [NKN-BNK. (Na0.5K0.5)NbO3 with 1 ~ 5 mol% Bi0.5(Na0.90K0.10)0.5TiO3 has been prepared following the conventional mixed oxide process. It can be concluded that the NKN-BNKT ceramics have orthorhombic structures in the case x 0.03. With increasing BNKT content (x=0.04 to 0.05), however, the structure changes from orthorhombic to rhombohedral phase. Above results demonstrated that the MPB between orthorhombic and rhombohedral phases exits in the solid solution with the BNKT content of x=0.03. At the MPB composition, the cryctalline structure of ceramics is considered to be a coexistence of orthorhombic and rhombohedral phase. Owing to the phase coexistence at the phase boundary, there exists a different symmetry regions (DSR) near the MPB. The DSR boundary motion increases the dielectric permittivity and piezoelectric coefficients. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (KT33), planar coupling coefficient (kp), thickness coupling coefficient (kt) and piezoelectric constant (d33)of 0.98NKN-0.02BNKT ceramics were 1180, 30%, 58%, and 180, respectively.
Large Remanent Polarization and Low Leakage Current in High-Tc 0.2Bi (Ni1/2Ti1/2)O3-0.8PbTiO3 Ferroelectric Thin Films
Authors: Xie Zhen Kun , Yue Zhen Xing
Published: March 2014

High Curie-temperature (Tc) polycrystalline 0.2Bi (Ni1/2Ti1/2)O3-0.8PbTiO3 (0.2BNT-0.8PT) thin films were fabricated on Pt (111)/Ti/SiO2/Si substrates via an aqueous chemical solution deposition (CSD) technique. The thin films exhibited good crystalline quality and dense, uniform microstructures with an average grain size of 55 nm. The dielectric, piezoelectric and ferroelectric properties of the films was investigated. The permittivity peak appeared at 485 °C, which was 100 °C higher than that of Pb (Zr,Ti)O3 thin films. The local effective piezoelectric coefficient d33 was 45 pm/V at 3V. Moreover, a large remnant polarization with 2Pr up to 92 uC/cm2 and a small leakage current of 2.2×10-5 A/cm2 under an electric field of 400 kV/cm were obtained. The magnitude of the measured polarization and the high Curie temperature make the 0.2BNT-0.8PT films promising candidates for application in high-temperature ferroelectric and piezoelectric devices.
Effect of Uniaxial Compressive Stress on the Partially Fatigued Soft Lead Zirconate Titanate Piezoelectric Ceramics
Authors: Peng Bin , Yue Zhen Xing
Published: March 2014

Uniaxial compressive stress was applied during fatigue process of soft lead zirconate titanate piezoelectric ceramics and their fatigue resistance was improved when the stress was larger than 20MPa. Before fatigue, compressive stress had a strong depolarization effect and restricted domains switching behavior under large electric field and domain walls motion under small electric field. However, in a partially fatigued state, while domains switching behavior was still restricted by compressive stress, domain walls motion was enhanced. Removal of the applied stress after partial fatigue induced the remnant polarization restored significantly.
The Preparation and Properties of (Na0.5+xK0.5-2xLix)NbO3 Lead-Free Piezoelectric Ceramics
Authors: Ma Hong Yun , Liu Yan Gai , Zhao Jin Qiu , Huang Zhao Hui , Fang Ming Hao
Published: March 2014

In this paper, the KNN powders with Li+ substituted (K0.5Na0.5)+ were prepared by the sol-gel method in order to make powders pure, (Na0.50+xK0.50-2xLix) -NbO3 (x=0, 0.04, 0.06, 0.08) ceramics were prepared by pressureless sintering. The phase composition of powders was determined by XRD. The effects of the Li+ substitution on piezoelectric and ferroelectric properties of ceramics were systematically studied for determining optimal Li+ content. Li+ can significantly increase the piezoelectric constant of ceramic. When Li+ content was 0.04, piezoelectric properties of ceramics were the best, d33=115 pC/N, Pr=6.35 μC/cm2, Ec=14.24 kV/cm.
NOx Sensing Performances of Mixed-Potential-Type Gas Sensor Based on Stabilized-Zirconia and La5/3Sr1/3NiO4 Sensing Electrode
Authors: Chen Ying , Li Xiang Dong , Xia Feng , Xiao Jian Zhong
Published: March 2014

Abstract. This article attempts to use a new sensing electrode material La5/3Sr1/3NiO4 for mixed-potential-type NOx sensors as they are high ionic conductivity, close thermal expansion coefficients to electrolytes (YSZ), low-cost and stable even at above 1000 °C. The nanostructured La5/3Sr1/3NiO4 was synthesized as a sensing electrode (SE) for the mixed-potential-type yttria stabilized zirconia (YSZ)-based NO sensor by a sol-gel method. The synthesized La5/3Sr1/3NiO4 powders were characterized using XRD, BET and FESEM. The sensing characteristics were examined in the temperature range of 400-700 °C. At 450 °C, the sensor exhibited the biggest response (about 20.3 mV for 1000 ppm NO). Moreover, the sensor response and recovery were generally rapid at all the temperatures. This work demonstrated that the La5/3Sr1/3NiO4 can be an effective sensing electrode candidate of mixed-potential-type NO sensors.
Mg2CuxFe1O3.5+x Mixed Metal Oxides as Ammonia Sensitive Material of Ammonia Sensors
Authors: Li Xiang Dong , Chen Ying , Zhou Li Hong , Xia Feng , Xiao Jian Zhong
Published: March 2014

Mg2CuxFe1O3.5+xmixed metal oxides were found to be active catalysts for the selective oxidation of ammonia. In this paper, Mg2CuxFe1O3.5+xmixed metal oxides were prepared by co-precipitation method and calcined at 600°C for 12 h in an air atmosphere, then ammonia sensors have been made by screen-printed Mg2CuxFe1O3.5+xelectrode on the electrolyte (8moleYSZ) surface and sintered at 1126°C for 1h in an air atmosphere. The samples were characterized by XRD and ESEM. The performance of ammonia sensors were tested in different concentration of ammonia. It can be found that Mg2Cu0.25Fe1O3.75electrode showed a higher response value and good sensitivity to ammonia at 350°C, the value of sensitivity is 226.6mV/decsde. The influences of Cu content on the ammonia response performance of Mg2CuxFe1O3.5+xmixed metal oxides electrodes are discussed.
Zirconia Fiber Separator for Nickel-Hydrogen Battery
Authors: Tang Jie , Li Chuan Shan , Du Xiao Yong , Zhang Ming Xia , Yue Shuang Shuang , Li Ru , Zhou Chang Ling , Wang Chong Hai , Tang Jian Xin
Published: March 2014

Zirconia fiber separator is one of the important materials of nickel-hydrogen battery .In this paper,we studied the factors affecting the properties of zirconia fiber separator used as nickel-hydrogen battery separator, which prepared by precursor process, including the precursor fibers,fibrous cloths,concentration of the precursor solution and the heating rate before 500oC.The results show that, because the gully structure copied the precursor fibers, as well as smaller diameter of the fiber has larger specific surface area, so the zirconia cloth has the higher absorption capacity and retention ability of alkal. In the same way as woven, the low fabric areal density is beneficial to the absorption ability. When the concentration of the precursor solution is 1.36g/ml, the properties of the zirconia fiber separator is the best. If the heating rate is too fast, will cause a decrease in performance of zirconia fiber separator. The diameter of the fibers in the zirconia fiber sepatator is about 4-5μm, the main phase of the separator is tetragonal zirconia.
Annealing Temperature Dependent Ferromagnetic Behaviors Observed in Highly Orientated Pure NiO Thin Films
Authors: Zhang Yu Jun , Lin Yuan Hua , Nan Ce Wen
Published: March 2014

Transition metal (TM) doped NiO is a promising candidate of p-type oxide diluted magnetic semiconductors (DMSs), which shows obvious room-temperature ferromagnetism. When researching the magnetic properties of DMSs, it is very important to get rid of ferromagnetic impurity phases by optimizing the preparation process. For this purpose, pure NiO thin films have been deposited by a pulsed laser deposition method and annealed by different annealing process. As-deposited or low-temperature annealed films show room-temperature ferromagnetism and high-temperature annealed films are not ferromagnetic. Nickel metal should be the origin of ferromagnetism in these thin films. On the other hand, high annealing temperature influences the microstructure of the film surface a lot. These results show a useful method to eliminate ferromagnetic impurity in NiO thin films and to optimize the preparation parameters of TM doped NiO thin films.
Photoelectrochemical Activity of Cu-Loaded TiO2 Nanotube Arrays by AC Electrodeposition
Authors: Zhao Jian Ling , Fan Qiao Wen , Mi Ying Juan , Yang Jing , Wang Xi Xin
Published: March 2014

This work presents a novel approach for preparing Cu-loaded TiO2 nanotube arrays through alternating current electrodeposition. The Cu content loaded on the arrays was controlled by changing the concentration of Cu (NO3)2 solution, deposition voltage and time. The surface morphology and crystal structure of Cu-loaded TiO2 nanotube arrays were characterized by scanning electron microscopy (SEM) and the X-ray diffraction (XRD). The effects of Cu content on the photoelectrochemical property were studied in detail. Results show that Cu-loaded TiO2 nanotube arrays have evidently enhanced photoelectrochemical activity. The photocurrent of Cu-loaded TiO2 nanotube arrays prepared in 0.00625 mol/L Cu (NO3)2 solution at 12 V for 20 seconds was 5.7 and 2.3 times as that of unloaded TiO2 nanotube arrays under visible and UV radiation, respectively.
Chemical and Physical Processes in the Synthesis of Romancement from Clay and Dolomite
Authors: Kirilovica Inta , Krage Linda , Vitina Inta , Igaune-Blumberga Silvija
Published: March 2014

This work deals with the synthesis of binder, similar to historic dolomitic romancement, from mixture of clay and dolomite instead of traditionally used marlstone, thus widening the range of raw materials. In the territory of Latvia dolomitic romancement was widely known and applied in the construction of buildings since late 19th till the middle of 20th century. Nowadays the local dolomitic marlstone is not sufficiently available. As the scientists have faced the problem adjusting compatible material for restoration of historical buildings of given time period, research is done with the aim to investigate the synthesis of romancement type binder from widespread local mineral raw materials for the restoration purposes. In given paper the chemical and physical processes in the synthesis and also obtained properties are discussed.
The Influence of Different Molten Salt Systems on Zinc and Bismuth Tungstate Formation
Authors: Kodols Maris , Didrihsone Sabine , Grabis Janis , Rozenberga-Voska Laura
Published: March 2014

The influence of different molten salt environments on formation of tungstates has been studied. Well crystalline and pure Bi2WO6 have been prepared in potassium nitrite KNO2 (350°C), potassium chloride KCl (800°C) and mixture of potassium-sodium sulphates K2SO4-Na2SO4 (800°C), but ZnWO4 have been successfully synthesized in sodium nitrate NaNO3 (350°C), mixture of sodium-potassium chlorides NaCl-KCl (680°C), potassium chloride KCl (780°C) and mixture of potassium-sodium sulphates K2SO4-Na2SO4 (850°C). The higher surface area and photocatalytic activity show powders prepared at lower temperature.
Effect of Oxidation on Sliding Wear Behavior of NiCrSiB-TiB2 Plasma Sprayed Coatings
Authors: Umanskyi Oleksandr , Hussainova Irina , Storozhenko Maryna , Terentyev Oleksandr , Antonov Maksim
Published: March 2014

The main goal of this work is to study dry sliding wear behavior of NiCrSiB-TiB2plasma sprayed coating against NiCrSiB coating. NiCrSiB-based powders with 10, 20, 40 wt.% TiB2particles content were deposited on steel substrates by plasma spraying. The structure of NiCrSiB-TiB2coatings consists of Ni-based matrix and TiB2and CrB grains. Among the coatings studied, the NiCrSiB-20wt.%TiB2shows excellent wear-resistance. The worn surfaces were observed using scanning electron microscopy and Auger electron spectroscopy to determine the wear mechanisms.
Effect of Mg Content on Thermal Stability of β-Tricalcium Phosphate Ceramics
Authors: Salma-Ancane Kristine , Stipniece Liga , Irbe Zilgma , Sokolova Marina , Krieke Guna , Berzina-Cimdina Liga
Published: March 2014

β-Tricalcium phosphate bioceramics with small, close to bone-like amounts of Mg were obtained by modified precipitation method and following sintering. The effect of small amounts of Mg on the thermal stability, microstructure and sintering behavior of β-tricalcium phosphate bioceramics was evaluated. Addition of small amounts of Mg, can induce a remarkable effect on the physic-chemical properties of β-TCP and therefore the chemical composition of the starting materials should be controlled.
Effect of Thermal Treatment on Thermoelectric Properties of Extruded TiO2 Ceramics
Authors: Pura Agnese , Locs Janis , Berzina-Cimdina Liga
Published: March 2014

TiO2samples were obtained by extrusion process, sintered in air at 1000 °C, 1100 °C, 1200°C and 1300 °C and, afterwards, thermally treated under vacuum conditions at 1250 °C for 1 hour applying two different heating/cooling rates (2 °C/min and 5 °C/min). It was found that thermal treatment conditions substantially affected thermoelectric properties of the samples. Increasing sintering temperature, during the sample thermal treatment in air, the electrical conductivity of the specimens increased, while Seebeck coefficient decreased. With an increase in the heating rate during the vacuum heat treatment of the samples, the electrical conductivity of the samples decreased, while Seebeck coefficient increased.
The Surface Stereometry and Microstructure of Steel 100CrMnSi6-4 after Ablation Laser Texturing
Authors: Napadłek Wojciech , Bogdanowicz Zdzisław , Chrzanowski Wojciech , Król Artur
Published: March 2014

Publication presents an analysis of possibility of applying ablation laser texturing of 100CrMnSi6-4 bearing steel in the tribological aspect. Selection of different variants of laser micromachining, including pulsed radiation (λ=1.064 μm), and different variants of geometric surface texture, characteristic surface stereometry was obtained with regular arranged lubrication microchannels on the surface roller bearing steel. Maximal hardness in the melted and laser hardened zone, inside the micro-container and in its nearby zone, increased up to 800÷1000 HV0.05 (about 60÷75% increase) in comparison to the core hardness (610÷660 HV0.05). Local hardness increase even up to 1100 HV0.05 was noticed. No micro-cracks in the surface layer neither in the lubricant micro-containers were found. Moreover, no material degradation in the cross-sections in the micro-containers was noticed.
Evolution of TiN Coating Surface Roughness during Physical Vapor Deposition on High Speed Steel Substrate
Authors: Kupchenko Leonid , Tali Rauno , Adoberg Eron , Mikli Valdek , Podgursky Vitali
Published: March 2014

TiN coatings with different thickness were prepared by arc ion plating (AIP) physical vapor deposition (PVD) on high speed steel (HSS) substrates. TiN coatings surface roughness was investigated by atomic force microscopy (AFM) and 3D optical profilometry and growth kinetics was described using scaling exponents β and α. The growth exponent β is 0.91-1.0 and the roughness exponent α is 0.77-0.81. Due to relatively high value of the exponent α, the surface diffusion is likely predominant smoothening mechanism of TiN growth.
Influence of Coal on the Wear Behavior of Steels in 3-Body Conditions
Authors: Petrica Marcela , Peissl Sven , Badisch Ewald
Published: March 2014

Abrasive and erosive properties of coal can lead to serious operational problems in mining industry. Here the abrasive medium is varied, containing often fractions of quartz, pyrite, and contents of coal which can be also mixed with water resulting in an abrasive slurry mixture. A better understanding of the dependence between the environmental and systematic conditions of the tribological processes that happen in ore mining and the wear behaviour of steels can be achieved only by analysing each parameter that forms these tribological processes. The Steel Wheel Abrasion Test (SWAT) represents a testing method which is capable of experimentally modelling the high stress wear environment typical for mining industry. The aim of this work exposes a comparison between the dry and slurry tribocontact in terms of wear, as well as the influence of coal simulating real field conditions.
The Formation of Microstructure in High Strength Concrete Containing Micro and Nanosilica
Authors: Toropovs Nikolajs , Bajare Diana , Sahmenko Genadijs , Krage Linda , Korjakins Aleksandrs
Published: March 2014

This article presents the results of microstructural investigation of high strength concrete containing microsilica and nanosilica (amorphous SiO2) as an active pozzolanic admixture. Micro and nanosilica react with calcium hydroxide producing calcium silicate hydrates (C-S-H), thus the voids and pores within concrete are filled and new minerals are formed in the gaps between cement grains and aggregate particles. Unreacted round microsilica and nanosilica particles were registered using SEM even in 6 month old samples. The compressive strength results indicate that concrete still continues to harden after the 28-days of curing.