bluuebunny/crossref_metadata_2025 huggingface dataset:
Feed Rate on Velocity Field of Liquid Film in a Wiped Film Molecular Distillatory
Authors: Xiang Ai Shuang , Wang Xiao Ming , Xu Song Lin
Published: August 2012

Effect of feed flow rate on velocity field of evaporating liquid film in a wiped film molecular distillatory was studied with a computational fluid dynamics (CFD) method. Three assumptions were introduced in order to simplify modeling processes. According to our previous study, the RNG k-εturbulent model treating near-wall flow was properly used in this simulation. The volume of fluid (VOF) multiphase model was also applied to track the liquid-gas surface. A near-wall modeling method, enhanced wall treatment, was used to consider the effect of walls. Simulations were carried out in rotating coordinate system. All simulation results are reasonably identical with real situation and were discussed in several aspects. It was concluded that increment of feed flow rate would reduce the turbulence of liquid film on the evaporator surface and then reduce the evaporation rate.
Discussion and Analysis on the Fungus, Humidity and Salt Fog Environmental Test
Authors: Yang Jing , Wang Xiao Hui , Ju Cheng Yu
Published: August 2012

The products which work in the field, aviation, marine and other harsh environmental conditions are easily to failure caused by humidity, slat fog and fungus, so the three anti-protection technology is particularly important. In this paper, we will analyze and talk about some key issues in the three anti-(humidity, slat fog and fungus) environmental test, such as the fungus testing cycle, the selection of fungus, the testing methods of the salt fog and humid , the evaluation of test results and so on. Give recommendations for improvement at last.
Rapid and Efficient Coupling Reaction of Azo Dyes in a Continuous-Flow Microreactor
Authors: Yu Wu Bin , Zheng Ming Ming , Gao Jian Rong
Published: August 2012

A convenient, rapid efficient method for the synthesis of azo dyes has been developed by coupling in a continuous-flow microreactor at room temperature. The advantage of this protocol is its continuousness, high efficiency and selectivity, short reaction time, and milder reaction conditions.
Some Properties and Detection Methods of Paper Sludge
Authors: Zhang Kai , Wu Chao Jun , Chen Jia Chuan
Published: August 2012

Some properties of paper sludge were analyzed, including water content, organic material content, pH value, ﬁber content, ash content ,C, H, S, N content and metal content of sludge in three sedimentation tanks.Besides,COD,SS, sludge concentration were analyzed and optical microscope photoes of sludge were got.The results showed that water content was high, organic material content was high, pH value of three sludges was alkalescent, metal elements were varied, lots of bacteria in wet sludge. From the first tank to the third one,COD and SS are gradually diminishing The research of sludge’s properties may be helpful to sludge treatment.
Study on the Extraction Technique of Poly-methoxyflavonoids from Citrus Peels by Using Response Surface Methodology
Authors: Li Cheng Ping , Wang Li Li , Jin Zai Su , Tang Lan
Published: August 2012

The objective of the present study is to extract polymethoxy ﬂavonoids such as nobiletin and tangeretin possess several important biological activities ,and to make full of use citrus peels which to be waste or by-product to develop a feasible eco-friendly process to maximize the yield of nobiletin and tangeretin. Box-Behnken design (BBD) based on response surface methodology (RSM) was adopted to investigate the effect of temperature (°C), time (h) and liquid-material ratio (ml/g)on nobiletin and tangeretin extraction. Under the optimum conditions, Extraction yielded polymethoxy ﬂavonoids content of more than 1.15mg/g
Production of Biodiesel in Supercritical Methanol and Related Correlation on Phase Equilibrium
Authors: Zeng Dan , Li Yang , Fang Tao
Published: August 2012

Biodiesel was prepared by methyl esterification and effects of different reaction conditions on the yield of fatty acid methyl esters (FAMEs) were investigated. The result of the orthogonal experiment analysis shows that the order of influential factors is ranked as reaction temperature > methanol-to-soybean-oil (M/O) ratio > reaction time. The maximum yield of 94.8 % has been achieved by reacting supercritical methanol and soybean oil in M/O ratio 4:2 (v/v) at 573 K for 45 min. Moreover, the higher M/O ratio, the higher yield of FAMEs will be obtained. At the temperature ranging from 533 k to 573 k, the yield rises significantly; however, since soybean oil decomposes over 573 K, the yield decreases oppositely. Time longer than 45 min has less effect on the final yield. In addition, the phase equilibrium data of supercritical methanol + C12 methyl esters and supercritical methanol + C18 methyl esters were separately correlated using the Peng-Robinson (PR) equation of state (EOS) with the Adachi-Sugie (AS) mixing rule.
Epoxy Resins Treated with Novel Silicon-Containing Flame Retardant
Authors: Gao Ming , Sun Ying Juan
Published: August 2012

A novel cheap macromolecular intumescent flame retardants (Si-MIFR), was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus-silicon characterized by IR. Epoxy resins (EP) were modified with Si-MIFR to get the flame retardant EP, whose flammability and burning behavior were characterized by UL 94, limiting oxygen index (LOI), dilatation, char yield, smoke density rating (SDR) and maximum smoke density (MSD). The epoxy resins were obtained for the UL 94 V-0 rating at low Si contents of 3.0 % get a LOI of 27.5% and char yield of 23.8%. Dilatation, SDR and MSD of EP/Si-MIFR decreased. The degradation behavior of the EP/Si-MIFR was studied by TG and EDX analysis. The experimental results exhibited that the initial decomposition temperature (IDT) was decreased, integral procedure decomposition temperature (IPDT) and amounts of Si and P at the residue were increased.
Preparation of Cationic Polyacrylamide Flocculant and its Application in the Treatment of Coal Slurry Wastewater
Authors: Gao Ming , Yang Yong Li , Xu Zhi Qiang
Published: August 2012

A cationic polyacrylamide flocculant (CPAM) for the coal slurry wastewater, was firstly synthesized using acrylamide and cationic monomer ethylene methyl propenoyl trimethylammonium chloride (DMC). The structure of the synthesized CPAM was characterized by means of FT-IR measurement, and the effects of various factors on flocculation performance were studied. The optimum flocculation can be achieved according to the dosage of flocculant between 2 and 5 mg/L, pH value of 6, temperature of 40°C, and the dosage of DMC in CPAM of 17.5%.
The Analyses of Lignin Structure and Molecular Weight Distributions of Small Fractions from Hardwood Dissolved Alkali Lignin
Authors: Dong Li Bin , Liu Yu
Published: August 2012

The Soda-AQ cooking of poplar was carried out in the study. Acid-precipitation was used in the process of the classification and separation of lignin from the black liquor, and different lignin samples were obtained. The molecular weight distributions of lignin samples were analysed by GPC(gel permeation chromatography). The results showed that the last stage of the dissolved lignin sample had low molecular weight. The structure of lignin was analysed by 31P-NMR,and the content of the aliphatic hydroxyl group, phenolic hydroxyl group and other functional groups was obtained. According to the molecular weight and the content of functional groups, the structural diagrams of lignin fragments which had small molecular weight was set up.
Application of Low Carbon Acid Compound Deplugging Technology
Authors: Wang Ji Gang , Zhang Zhe Ming , Zhao Ming Li
Published: August 2012

Formation damage is mainly due to the reduction of reservoir energy and the increase of flow resistance from reservoir. According to this theory, low carbon acid compound deplugging technology is introduced to improve well productivity. The compound blocking remover which will be used is consist of low carbon acid, rudimentary fatty acid and surfactant and so on. Where geological condition a large volume of carbon dioxide gas generate, through increasing the reservoir energy, removing all kinds of reservoir choke, the well productivity will increase effectively.
Study on Spectra and Mg-O Bond-Length of NaMg3Al(MoO4)5: Cr3+ Crystal at Low Temperature
Authors: Huang Yi , Miao Feng
Published: August 2012

Considering the crystal field parameter Dq and average covalent factor N, the energy levels of NaMg3Al(MoO4)5: Cr3+ crystal at 295 K are calculated by diagonalizing the energy matrix of 3d3. At low temperature 9 K the bond length of Mg-O is calculated by adjusting the value to fit the spectra of Mg site. The value of Mg-O bond length is 2.0528 Å. The equation relationship of Mg-O between bond length and temperature is achieved.The calculated values are consistent with the experimental spectra.
The Research of Oil-Shale-Dreg in Preparing Petroleum Proppant
Authors: Wang Duo , Yan Chun Jie , Wang Hong Quan , Qiu Xiu Mei
Published: August 2012

The oil-shale-dreg is the wastes after refining the oil shale to obtain the shale oil. But in the oil-shale-dreg, there are the massive mineral component, like the quartz, the feldspar, the clay ingredient and so on. After calcined, its structure becomes loose, owning the very low density and much ignition loss. In our study, we use different rate of oil-shale-dreg, bauxite and flux for granulation by using disk granulator. After high temperature we get low density Petroleum Proppant. The proppants have the high strength and the high flow conductivity. That is satisfied the national standards by adding 30% wt solid waste oil-shale-dregs residue to the bauxite.
The Polyetherification Modified Reaction on Silicone Oil
Authors: Xu Jin Yun , Han Shan Shan
Published: August 2012

Nowadays, polyether silicone oil is widely used in many aspects of chemical industry. In this paper, the synthesis of polyether modified polysiloxane was studied and its technology was the best choice. This paper discussed the synthesis of polyether modified polysiloxane materials during the synthesis ratio, catalyst amount, reaction time and temperature on the synthesis of polyether polysiloxane low conversion rate of hydrogen silicone oil. The results showed that synthesis of polyether modified polysiloxane of the best technology: the C=C of allyl alcohol and the Si-H in low-hydrogen silicone polyether feed ratio was 1:1.2, the catalyst material is 33 μg / g, the reaction temperature is 110 °C, reaction time to 8 h.
PVA-SA Immobilized White-Rot Fungus to Treat Papermaking Wastewater
Authors: Yang Chao , Pang Zhi Qiang , Chen Jia Chuan , Yang Gui Hua
Published: August 2012

Effects of white-rot fungus BYBF treatment on properties of papermaking wastewater were investigated. The optimal immobilized conditions were the PVA 5%, SA 2.3%, active carbon 2%, 2% CaCl2 in saturated boric acid solution and pH = 7. Using these materials to form immobilized beads, which have great mechanical strength and big specific surfaces. Using these beads to immobilized BYBF to treating terminal wastewater. COD decreased from 411mg /l to 352mg/l in 4 days.
Process of Kraft Pulping of Fast-Growing Poplar and Defibration Point
Authors: Cui Yu , Chen Jia Chuan , Yang Gui Hua
Published: August 2012

The process of kraft pulping of Fast-growing Poplar was studied,by determining the lignin contents including Klason lignin and acid soluble lignin, the yield of pulping, the rate of carbohydtare degradation and delignification rate. Results indicated that the delignificaton of Fast-growing Poplar in kraft pulping can be divided into three distinguishable stages. (a)The initial delignification stage before 140°C,the rate of delignification reaches to 35.76%; (b)The bulk delignification stage, the rate of delignification reaches to 90.50%，in the period from 140°C to 170°C and for 30 min; (c)The residual delignification stage,the rate of delignification exceeds 95.56%. The defibration point was reached when cooking temperature raised to 170°C and for 30 min with 52.22% pulping yield ,17.83 kappa number.
Surface Nanocrystallization of Nickel Produced by High-Current Pulsed Electron Beam Irradiation
Authors: Han Zhi Yong , Zou Hui , Wang Zhi Ping , Guan Jin Tong , Guan Qing Feng
Published: August 2012

The nanocrystalline surface was obtained on bulk pure nickel by using high-current pulsed electron beam (HCPEB) technique. The temperature field induced by HCPEB was numerically simulated. The structures of the nanocrystallized surface were characterized by scanning electron beam (SEM), which showed that after HCPEB irradiation, the initial coarse-grained structure on the surface was refined into fine grains with sizes of about 70nm. It was revealed that melting surface caused by HCPEB irradiation and subsequently rapid cooling was the dominant mechanism of the surface nanocrystallization of bulk nickel. The HCPEB technique provides a new method for rapid fabricating surface-nanocrystallized materials.
Preparation and Photocatalytic Activities of α-Fe2O3/Sb-doped SnO2 (ATO) Nanocomposites
Authors: Xu Dan , Lu Chun Hua , Zhang Dun Pu , Song Jian Bin , Ni Ya Ru , Xu Zhong Zi
Published: August 2012

The novel photocatalyst of α-Fe2O3/Sb-doped SnO2(ATO) nanocomposites were fabricated by two-step process of hydrothermal and precipitation method. The structure, size, magnetic behavior and absorption property were characterized by XRD, TEM, VSM and UV-Vis absorption spectrum. The composites with low mole ratio of ATO have more pronounced photocatalytic activities. The optimum photocatalytic activity in our experiments appears at the mole ratio of nFe:nSn=1:0.25. The α-Fe2O3/Sb-doped SnO2nanocomposites have better photocatalytic activities than α-Fe2O3/SnO2nanocomposites. The results show that the doping of Sb ions can improve the capture ability of electrons and consequently enhance the photocatalytic activities of the composite system.
A Novel Disinfection Material-Nano Ag Particle Impregnated Media
Authors: Yang Wen Han , Tsai Tsung Yu , Wu Chih Chao , Hu Tai Lee , Kan Chi Chuan
Published: August 2012

In this study, the nano-silver impregnated media (NAg-ball) was proposed to inactive E. coli in water. After 24 h of contact with NAg-ball, about 99 % removal of E. coli from the water sample with an initial bacteria loading oItalic textf 103 - 105 CFU/ml was observed. According 32 day repetitive use, periodical surface cleaning would be suggested to maintain the high inactivation lasting of NAg-ball. The dosing of 1: 20 (Nag-ball: water) was found to be the best and most suitable in a 500 L pilot scale. This result confirmed the existence of synergistic effect lower dose shall be expected to treat the same loading of bacteria for further larger scale. Toxicity Characteristic Leaching Procedure (TCLP) test revealed trace amount of Ag, Cu, Cr and Zn released from NAg-ball into the treated water sample. In conclusion, nano-silver impregnated media has very good inactivation performance on E. coli. This NAg-ball provides a safe, convenient and effective solution in drinking water treatment, especially in the mountain area.
A Mild Method Prepared Carboxy Carbon Nanocage
Authors: Li Jiang Tao
Published: August 2012

Here we report for on the functionalization of ordered cage-type mesoporous carbons through a simple oxidation using ammonium perchlorate (AP). The degree of functionalization can be easily controlled by the simple adjustment of the oxidation parameters such as oxidation time, AP concentration and oxidation temperature. The functionalized materials have been unambiguously characterized by XRD, nitrogen adsorption, FT-IR and TEM measurements. It has been found that the functionalized carbon nanocage, ‘‘carboxy carbon nanocage’’.
Fabrication of Microporous PVDF Particles by an Emulsion Method and Control of Pore Structure
Authors: Luo Da Bing , Ma Tao
Published: August 2012

The Microporous Poly(vinylidene Fluoride) (PVDF) Materials Were Prepared by Emulsion in the Article, and through Appropriate Methods to Characterize Considerable Specific Surface Area and Excellent Pore Structure. with DMF as Solvent, Ethanol as a Diluent to Dissolve and Dilute PVDF, by Virtue of this Method to Destroy the Morphology of PVDF Structure, that Changed the Spherical Structure to Porous Structure, and to Get the Different Pore Size and Specific Surface Area through Controling the Speed of Dripping Water. the Structure Information, Surface Morphology and Specific Surface Area Were Determined by XRD, SEM (or Field Emission) and Specific Surface Area and Pore Size Analyzer, then Found the Regulation about Control of Pore Size and Specific Surface Area Preliminary.
The Phase Structure of Novel Polycarbonate-Based Polyurethane-Organoclay Nanocomposites
Authors: Pavličević Jelena , Sinadinović-Fišer Snežana , Špírková Milena , Budinski-Simendić Jaroslava , Borota Olga , Janković Milovan , Knez Željko
Published: August 2012

Polycarbonate-based polyurethane nanocomposites were prepared using one step procedure by addition of either organically modified bentonite or montmorillonite (1 wt. %). All aliphatic components (polycarbonate diol, hexamethylene-diisocyanate and 1,4-butane diol) were used as reactants. The hard segment content of obtained thermoplastic polyurethanes was 30 wt. %. Scanning electron microscopy (SEM) was performed to investigate the morphology of obtained hybrid materials. The structure of synthesized elastomers was studied by Fourier transform infrared spectroscopy (FTIR). In order to obtain the degree of phase separation and investigate the hydrogen bonding constitution, deconvolution of –NH and –C=O IR regions was done, using Gaussian equations. It was determined that the degree of phase separation is not influenced by addition of organoclays, indicating uniform dispersion of silicate layers in the polyurethanes, which was also confirmed by SEM experiments.
Submerged Culture Optimisation for Triterpenoids Production by Inonotus obliquus Using Response Surface Methodology
Authors: Chao Xiang , Xu Xiang Qun , Zhu Ling Hui
Published: August 2012

The medicinal mushroom Inonotus obliquus has been a folk remedy for a long time in East-European and Asian countries. It has been ascribed to a number of triterpenoids that show various biological activities. In this study, the response surface methodology was employed to optimise the medium composition for triterpenoids production by I. obliquus in shake flask culture. A fractional factorial design was used to evaluate the effects of different components in the medium. Glucose, peptone, yeast powder, and CaCl2 were important factors significantly affecting I. obliquus triterpenoids production. These selected variables were subsequently optimised using steepest ascent method, a central composite design, and response surface methodology. The optimal medium composition was (% w/v): glucose, 5.92; peptone, 0.23; CaCl2, 0.048; yeast powder, 0.12; KH2PO4, 0.1; MgSO4, 0.02. Under optimal conditions, triterpenoids production by I. obliquus reached 5.51%, representing an increase of 1.4-fold compared with that using the basal medium (3.98%).
Isobaric Vapor-Liquid Equilibria for the System Containing Acetic Acid at 101.3kPa
Authors: Xin Hua , Wang Xu Feng , Li Joshua Qing Song
Published: August 2012

Isobaric vapor-liquid equilibria (VLE) data for water + acetic acid, acetic acid + n-pentyl acetate, water + acetic acid + n-pentyl acetate systems have been measured at 101.33 k Pa using a recirculating still. The nonideality of the vapor phase caused by the association of the acetic acid has been corrected by the Hayden-O’Connellmethod. The three experimental binary data have been correlated by the NRTL and UNIQUAC models. The obtained NRTL model parameters from binary data have been used to predict ternary VLE data. The ternary predicted values obtained in this way agree well with the experimental values.
Composite and Real Hardnesses of Thin Coatings
Authors: Voronin Nikolay A.
Published: August 2012

The paper presents the results of an analysis of the mechanics of contact between a rigid sphere and an elastic rigidly plastic two-layer half-space that imitates a surface covered with a hard strengthening coating. Analytical dependences are derived which relate the surface hardness to the base and coating hard¬nesses within the whole possible range of the coating thickness. A new physical interpretation of the mechanism of the deformation of a layered solid is proposed for the range of the indentation depth that commonly characterizes the domain of the existence of the composite hardness. The obtained theoretical solutions are used to determine the ranges of the thicknesses within which the composite and real hardnesses of a hardened surface exist.
Electrical Studies on PZT Ceramic
Authors: Prasad N.V. , Ramaiah B. , Nathanial V. , Sekhar M. Chandra
Published: August 2012

Polycrystalline sample of PZT (52/48) was prepared by solid-state reaction method. X-ray analysis indicated the formation of single-phase. Electrical and impedance-spectroscopy plots were employed to analyze the electrical behavior of the sample, as a function of frequency, in the range of 0.01 Hz to 1 M Hz at different temperatures. Spectroscopic and complex plots indicated non-Debye dielectric relaxation. Detailed electrical studies revealed that the conduction is through hoping of electrons (extrinsic region) at lowers temperature and migration of oxygen vacancies at high temperature (intrinsic region). The results are explained using Euryod’s conduction model and confirmed with pyroelectric and ferroelectric data.
Synthesis of Tb3+-Doped Ca-Deficient Hydroxyapatite and its Photoluminescence for White Light-Emitting Diode Application
Authors: Zhang Zhan Hui , Wang Han , Chen Li , Guo De Xing , Cai Ke Qin , Liu Xiao Jun , Huang Zhi Liang
Published: August 2012

Green-emitting Tb3+-doped Ca-deficient hydroxyapatite phosphor was successfully prepared from natural collophanite. The effects of (Tb+Ca)/P values on the crystal phases and luminescent properties of the prepared products were discussed. XRD results revealed that Ca-deficient hydroxyapatite was a biphase compound of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), and its crystal phase transformed to HA with the increasing values of (Tb+Ca)/P. Photoluminescence measurements showed that the products presented intensely green emission peaking at 545 nm under near-ultraviolet excitation and the luminescent intensity had great correlation with the content ratios of β-TCP to HA. When (Tb+Ca)/P=1.3, the luminescent intensity of Tb3+-doped Ca-deficient hydroxyapatite reached the maximum value, which was much stronger than that of Tb3+-doped HA. These results indicate that Tb3+-doped Ca-deficient hydroxyapatite phosphor is suitable for potential application in white light-emitting diode (LED).
Tribological and Corrosive Properties of Tin/AlN Multilayer Film
Authors: Tang Pu Hong , Mao Jie , Feng Chong You
Published: August 2012

TiN/AlN nanoscale multilayer films were deposited by pulsed laser ablation on silicon, with different argon and nitrogen gas flow rates. The total thickness of the TiN/AlN multilayer film was approximately 1μm. The friction and corrosion properties were studied by tribological and corrosive tests. In tribological tests, ball-on-disc was used to determine coefficients of friction and wear rates. The coefficient of friction against a Si3N4 ball varied considerably between films, as does the wear rate. The lowest coefficient of friction μ=0.97 was shown at sample 1, whereas the other three multilayer films were ranged from 1.0 to 1.5. In corrosion test, the anodic polarization characteristics were measured in a 3.5% NaCl solution at room temperature to examine the corrosion resistance. The potentiodynamic polarization measurements showed that for all the multilayer films the corrosion potential shift to higher values, and the corrosion current density decreased with increasing of nitrogen gas flow rate, which indicate a higher nitrogen partial pressures lead to a better corrosion resistance.
Coupled Thermo-Mechanical FEA of Three-Roll Cross Rolling Process for Rings with Small-Hole and Deep Groove
Authors: Ma Qi , Hua Lin , Qian Dong Sheng
Published: August 2012

Ring parts with small-hole and deep groove such as duplicate gear and double-side flange, are widely used in various engineering machineries. Three-roll cross rolling (TRCR) is a new advanced plastic forming technology for the processing of rings with small-hole and deep groove. In this paper, a 3D coupled thermo-mechanical FE model for TRCR of ring with small-hole and deep groove is established under ABAQUS software environment. By simulation and analysis, the evolution and distribution laws of strain and temperature in the forming process are revealed, and the effects of the key process parameters on the deformation uniformity are explored. The results provide valuable guideline for the technological parameter design and optimization.
Low-Temperature Sintering Lead-Free Barium Titanate-Based X7P Ceramics with Bi2O3 Dopant and ZnO–B2O3 Flux Agent
Authors: Zhang Bao Lin , Wu Shun Hua
Published: August 2012

The sintering temperature of BaTiO3 powder was reduced to 870°C due to the H3BO3-ZnO-Bi2O3 addition.Excellent densiﬁcation was achieved after sintering at 870°C for 15h. The low sintering temperature of newly developed capacitor materials allows a co-ﬁring with pure silver electrodes.The dielectric constant and the temperature stability of the dielectric constant satisﬁed the X7P requirements, which dielectric properties of were ε25°C≥ 2800, εr/εr25°C≤±10% (–55~125°C), tanδ≤1.5% (25°C).
Relaxor Properties and Tunability of Electron-Irradiated Thin Poly(vinlidene fluoride-trifluoroethylene) Copolymer Film
Authors: Tian Li , Meng Xiang Jian , Yang Jing , Sun Jing Lan , Yuan Sheng Zhao , Wang Jian Lu , Bai Wei , Chu Jun Hao
Published: August 2012

The effect of high energy electron irradiation on poly(vinlidene fluoride-trifluoroethylene) copolymer film with thickness about 180 nm has been studied. Both dielectric spectroscopy investigation and X-Ray Diffraction show that all-trans conformation of pre-irradiated films is transformed to trans-gauche conformation after irradiation. The relaxor behavior of irradiated sample obeys the modified Curie-Weiss and Vogel-Fulcher law. And the tunability is increased from 42% to 63% after irradiation.
Simulation of Ductile Fracture in an Aluminum Alloy Using Various Criteria
Authors: Guo Jun Hang , Murakami Ri Ichi , Zhao Sheng Dun
Published: August 2012

There are many models and failure criteria have been developed to predict the ductile fracture (DF) in metal plastic deformation. But usually, it is difficult to select a suitable model and the corresponding criterion from them. So, finding a way to identity their applicability and reliability is useful for selecting these DF criteria. In this paper, ductile fracture of aluminum alloy A5052P-H34 is studied by experiments and finite element simulations. In experiments, the mode I crack was obtained by uniaxial tension of plate with a circular hole in the center. The von Mises yield model and continuum damage mechanics based Rousselier model and modified Rousselier model are chosen to describe the material behavior. Three failure criteria, including the Cockcroft-Latham integral, maximum shear stress theory and critical void volume fraction criterion are investigated to determine their reliability in ductile failure prediction. These constitutive models and DF criteria are implemented by user material subroutine in ABAQUS/Explicit to predict the crack. And the crack initiation and propagation is implemented by element erosion method. By comparing the experiments and simulations, the modified Rousselier’s model with the corresponding criterion shows agreement with the experiments.
Effect of Strain Rate on Mechanical Behavior of Extruded AZ31B Magnesium Alloy under Tensile Deformation
Authors: Geng Chang Jian , Wu Bao Lin , Wang Yan Dong
Published: August 2012

Uni-axial tensile test was conducted at room temperature on a weak texture AZ31B magnesium alloy at different strain rate, from 2.8×10-5s-1 to 1.1×10-1s-1. The mechanical behavior was investigated. It was found that as strain rate is increased, flat character of the stress-strain curves can be found and {10-12} tension twinning is responsible for this phenomenon. The sample exhibites a brittle fracture at 1.1×10-1s-1 strain rate while exhibites a ductile fracture character at 2.8×10-5s-1 strain rate.
Effects of Cooling Methods on Microstructure and Lattice Parameters of FGH95 Superalloy
Authors: Xie Jun , Tian Su Gui , Xie Guang Liang , Zhou Xiao Ming
Published: August 2012

By means of different cooling methods, microstructure observation and X-ray diffraction analysis, an investigation has been made into the influences of the cooling methods on the microstructure and lattice parameters of FGH95 superalloy. The results shown that, after the solution treated alloy is cooled at different mediums, fine γ′phase and carbide particles dispersedly distribute in the grain and coarser γ′phase discontinuously precipitates along grain boundaries. After X-ray diffraction analyzed, the γ and γ′phases in “molten salt cooling” alloy possess larger lattice parameters, and a bigger lattice misfit exists in the interface between the γ and γ′phases.
Surface Modification of Pure Titanium by High Current Pulsed Electron Beam
Authors: Cai Jie , Wan Ming Zhen , Zou Yang , Lv Peng , Han Zhi Yong , Wang Zhi Ping , Guan Qing Feng
Published: August 2012

Polycrystalline pure titanium was irradiated by high-current pulsed electron beam (HCPEB). The microstructure changes and material strength were investigated by using microhardness tester, optical microscope, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) technique. The experimental results indicate that many craters are inevitably formed on the irradiated surface. The eruption of the craters makes the material surface cleaned, which can improve the corrosion resistance of materials. Furthermore, martensitic structure, ultra-fine grains and high-density dislocations are formed on the irradiated surface, which increase the hardness of the treated samples. The microhardness of 20-pulsed sample reaches 286Hv, which is 71% higher than the initial sample. Martensitic transformation, grain refinement and dislocation strengthening induced by HCPEB treatment are the dominating mechanism for the improvements of material strength. It is suggested that HCPEB technique is becoming an effective approach to surface modification for pure titanium and titanium alloy.
Current Status of Ti PM: Progress, Opportunities and Challenges
Authors: Peter William H. , Chen Wei , Yamamoto Yukinori , Dehoff R. , Muth T. , Nunn Stephen D. , Kiggans Jim O. , Clark Michael B. , Sabau Adrian S. , Gorti Sarma , Blue Craig A. , Williams James C.
Published: August 2012

Utilization of titanium components made by powder metallurgy methods has had limited acceptance largely due to the high cost of titanium (Ti) powder. There has been renewed interest in lower cost economical powders and several Ti reduction methods that produce a particulate product show promise. This talk summarizes work done at Oak Ridge National Laboratory to consolidate these economical powders into mill products. Press and sinter consolidation, hot isostatic pressing (HIP) and direct roll consolidation to make sheet have been explored. The characteristics of the consolidated products will be described as a function of the consolidation parameters.
A Novel Process for Making Spherical Powders of High Nb Containing TiAl Alloys
Authors: Lu Xin , Zhu L.P. , Qu Xuan Hui
Published: August 2012

A novel process was developed to make micro-fine spherical high Nb containing TiAl alloyed powders in quantity. Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y(at%) ingot prepared by vacuum induction melting was heat-treated for homogenization, and then machined with a crusher. The chippings were refined by fluidized bed jet milling, and subsequently spheroidized with radio frequency (RF) argon plasma. The effects of processing parameters on powder characteristics were studied. By fluidized bed jet milling, the particle size and distribution uniformity both decline with the rise of classifier frequency. Above 5800rpm, the number-average diameter is lower than 20μm with a bimodal particle size distribution. The powders consist of coarse plate-shaped particles and some finer flaky debris, and with the further rise of the frequency, the amount of debris gradually increases. The plasma-spheroidized powders are found to possess good sphericity and composition homogeneity with phase dominated by supersaturated α2-Ti3Al. The granulometric characteristics of the spherical powders strongly depend on those of the feed powders. For the jet milled powders below 5800rpm, due to the relatively lower size distribution uniformity, the fine particle fraction reduces after spheroidization, which causes an obvious improvement of distribution uniformity and the corresponding increase of number-average diameter
Role of Surface Contamination in Titanium PM
Authors: Ivasishin Orest M. , Savvakin Dmytro G. , Gumenyak Mykola M. , Bondarchuk Oleksandr B.
Published: August 2012

The powder metallurgy (PM) approach is widely used for cost-effective production of titanium alloys and articles. In the PM approach the large specific surface of starting powders heightens the risk of excessive impurity presence and, hence, degradation of final alloy properties. The present study analyzes the opportunity to produce sintered commercially pure titanium (CP-Ti) with acceptable impurity content from powder materials. Starting titanium and titanium hydride powders were comparatively examined. The impurity elements (oxygen, chlorine, carbon) and their conditions on the powder particle surface, as well as the surface processes and gases emitted from powders upon heating, have been analyzed by means of surface science techniques. The role of hydrogen emitted from titanium hydride in material purification has been discussed. The opportunity to produce titanium materials with final admissible content of interstitials (O, C, Cl, and H) using starting titanium hydride powder has been demonstrated.
Metal Injection Moulding of Low Interstitial Titanium
Authors: Sidambe Alfred T. , Derguti Fatos , Todd Iain
Published: August 2012

Metal injection molding (MIM) is a well-established, cost-effective method of fabricating small-to-moderate size near net-shape metal components. In the MIM of titanium (Ti), one of the key points in the process is the interstitial contamination, especially oxygen. This study examines the sources of interstitial contamination during the metal injection moulding of commercially pure (CP-Ti) and Ti6Al4V (Ti-64) alloys. Also presented is a route to control and minimize the contamination in the sintered parts. The effect of the levels of oxygen contamination on the mechanical parts is also presented in the work.
Metal Injection Moulding of Titanium and Titanium-Aluminides
Authors: Ebel Thomas , Milagres Ferri Orley , Limberg Wolfgang , Oehring Michael , Pyczak Florian , Schimansky Frank Peter
Published: August 2012

Metal injection moulding (MIM) attracts growing interest as an economic net-shape manufacturing technique for the processing of titanium and titanium alloys. Even for titanium-aluminides, intended for high-temperature applications, MIM is seen as a reasonable technique to overcome processing problems with conventional methods. In this paper, basic requirements in terms of raw materials, facilities and processing in order to produce high performance components are presented. Main focus is laid on the well-known Ti-6Al-4V alloy. It is shown that the tensile properties of specimens after MIM processing can exceed the requirements given by ASTM standards even without performing an additional HIP process. For an oxygen content ranging from 0.15 to 0.33 wt% plastic elongation yields excellent 14%. Fatigue measurements performed by means of 4-point-bending tests show that grain size is more important than residual porosity in order to achieve a high endurance limit. This is shown by addition of boron powder which refines the microstructure dramatically. The modified alloy Ti-6Al-4V-0.5B yields an endurance limit of 640 MPa compared to 450 MPa of MIM parts made from standard alloy powder. Sintered components from Ti-45Al-5Nb-0.2B-0.2C (at%) powder made by inert gas atomising (EIGA technique) and processed by MIM exhibit a residual porosity of only 0.2% and tensile properties comparable to cast material.
Removal of the Water Soluble Binder Components from Titanium and Titanium Alloy Powder Compacts Produced by MIM
Authors: Ewart Paul , Zhang De Liang , Ahn Seokyoung
Published: August 2012

This work investigates the debinding process of powder compacts formed by metal injection moulding (MIM) of feedstocks comprised of HDH Ti or HDH Ti-6Al-4V powder mixed with a binder of a predetermined ratio of water soluble polyethylene and wax. The full debinding process has three stages: a solvent debinding process to leach the water soluble component, a drying phase allowing the removal rate to be measured and a thermal treatment step for removing the wax components, leaving the backbone components to retain part geometry prior to sintering. Leaching of the water soluble component was monitored and the results were consistent with the general correlation which predicts that binder removal time increases by a factor of 4 when the section thickness is doubled. Uniformity of binder removal, defect formation and particle surface degradation in Ti MIM parts are also discussed.
Effects of Raw Powder Morphology and Size on Tensile Properties of SPS-Consolidated TiB/Ti Composites
Authors: Ota Akinori , Yamazaki Masahiro , Izui Hiroshi
Published: August 2012

Titanium matrix composites (TMC) exhibit excellent specific strength and corrosion resistance. TiB whiskers can be formed in titanium by solid-state reaction between titanium and TiB2 powders. The formation of TiB whiskers results in the improvement of tensile strength, Young's modulus and Vickers hardness. In this study, TiB reinforced pulverized or gas atomized pure titaniums were fabricated by spark plasma sintering. We focus on the effects of the powder morphology and size on the tensile properties of TiB/Ti composites. We will investigate the sintering performance and microstructures of TiB/Ti composites.
Tensile Properties of Ti-6Al-4V Discs Produced by Open Die Powder Compact Forging of Pre-Alloyed HDH Powders
Authors: Raynova Stella , Zhang De Liang , Gabbitas Brian
Published: August 2012

Open die powder compact forging was employed for consolidation of Ti-6Al-4V(wt.%) powders which were produced by a hydride-dehydride (HDH) process. The powders were initially warm-compacted into cylindrical shapes. Induction heating was used for preheating the compacts prior to forging into plates. The effect of the forging parameters such as temperature and pre-sintering time on the microstructure and tensile properties of the forged plates were studied. Porosity and the alpha-beta phase distribution were investigated to enable a better understanding of their effect on the fracture behaviour of the tensile tested specimens. The fracture surfaces of the broken tensile specimens were analysed using Scanning Electron Microscopy (SEM) to find the correlation between microstructure, residual porosity and fracture behaviour. A combination of high ultimate tensile strength of over 1200MPa and a good ductility reflected by an elongation to fracture of around 10% was achieved in some of the forged discs.
High Performance Titanium Alloy Compacts by Advanced Powder Processing Techniques
Authors: Miura Hideshi , Kang Hyun Goo , Itoh Yoshinori
Published: August 2012

In this paper, two kinds of advanced powder processing techniques such as Metal Injection Molding (MIM) and Direct Laser Forming (DLF) were introduced to fabricate complex shaped Ti alloy parts which have been widely used for various industrial and medical applications because of their excellent characteristics of low density, high corrosion resistance and high biocompatibility but need high processing cost because of poor workability. The MIM process has been tried to strengthen Ti-6Al-4V alloy compacts by addition of fine Mo, Fe and Cr powders, and enhanced tensile strength of 1030 MPa with 15.1 % elongation was obtained by an addition of 4 mass%Cr because of the microstructural modification but also the solution strengthening in beta phase. DLF process has been tried to improve the honeycomb porous structure from Ti-6Al-7Nb powder material, and the honeycomb structure with 300 m holes showed good mechanical compatibility and superb biocompatibility in osteoblasts culturing.
Weldability of Ti-6Al-4V Alloys Formed via Various Powder Consolidation Techniques
Authors: Hoye Nicholas , Li Hui Jun , Norrish John , Dippenaar Rian J. , Dehghan-Manshadi Ali
Published: August 2012

This study considers the weldability of Ti-6Al-4V alloys formed by various powder consolidation methods. Samples were prepared from commercially sourced pre-alloyed Ti-6Al-4V powder using both conventional press-and-sinter (PS) and the new novel resistance-heated pressing (RHP) methods. Fusion welding was executed by the gas tungsten arc (GTA) process with arc stability assessed in-situ by observations of the arc as well as monitoring of transient arc voltage. Results indicated equivalent arc stability between samples of RHP and commercially sourced wrought material while samples formed by PS showed high instability in arc initiation, attributed to high levels of porosity. Post weld analysis of mechanical hardness in powder based samples revealed no significant deviation in weld metal properties from welds conducted on commercially sourced wrought material. In all cases weld microstructures typical of Ti-6Al-4V alloys were observed with significant grain growth in the fusion and heat affected zones. Samples prepared by PS methods showed internal porosity due to gas evolution upon solidification, which may again be attributed to the highly porous initial microstructure.
Improvement of Ti Processing through Colloidal Techniques
Authors: Neves R.G. , Escribano J.A. , Ferrari Begoña , Gordo Elena , Sanchez-Herencia Antonio Javier
Published: August 2012

The colloid-chemistry control of metallic powders in aqueous slurries is proposed as a way to prepare Ti powders with small particle size for a better pressing behavior through the spray dry process. The chemical-physic behavior of titanium powders with two different particle size distributions dispersed in water has been studied by measuring the zeta potential as a function of pH, and dispersant concentration. The employment of poly-acrylic dispersants allowed the fabrication of stable slurries with solid contents up to 50 vol% that have been sprayed under different conditions to form agglomerates ranging between 50 and 200 µm. Conditions were selected to achieve spherical agglomerates formed by a broad distribution of particle sizes that shown excellent flowability. Agglomerates were pressed in a uniaxial die to measure the compressibility, showing an improvement in pressing behavior with respect to powders with bigger particle size. The sintering behavior is also improved, as values of 96 % of the theoretical density were obtained for compacts sintered in vacuum at 1100 °C for 30 minutes.
Resistance Heated Pressing (RHP): A Novel Technique for Fabrication of Titanium Alloys
Authors: Dehghan-Manshadi Ali , Hoye Nicholas , Jong Bob de , Dippenaar Rian J.
Published: August 2012

A novel powder metallurgical technique for the fabrication of titanium alloys has been developed by utilizing a pressure-assisted, resistance-heating sintering technique. In this technique, the high electrical resistance of oxide layers present on the surface of powder particles has been exploited to ensure effective resistance heating of green compacts. Ti-6Al-4V pre-alloyed powders of 100 µm size were compressed while being heated under a variety of conditions of sintering temperature, pressure and time. The outcomes of our experiments have proven that resistance heating can be a very effective means of heating during powder consolidation. The results have indicated that the required sintering time and temperature in the new resistance-heated sintering technique are much reduced in compared to sinter-press and/or hot isostatic pressing techniques, resulting in a refined microstructure with a concomitant improvement in mechanical properties.
Scandium (Sc) Behavior in High Temperature Ti Alloys
Authors: Ping De Hai , Wu S.Q. , Yamabe-Mitarai Y.
Published: August 2012

The microstructural evolution and elevated temperature tensile properties of Ti-6.6Al-5.2Sn-1.8Zr-(0~3.8)Sc (wt%) alloys have been investigated. The Sc-added alloys showed improved yield strength at 650°C and 750°C and with the elongation above 10%. Minor addition of Sc was found to significantly reduce the as-cast grain size. Higher amount of Sc additions resulted in the formation of high density of Sc-oxide, which causes the high strength at elevated temperatures and the reduction of ductility. High density of α2-Ti3Al fine precipitates with an average size of about 20 nm were observed inside equiaxed primary α (αp) grains in the Sc-free or minor Sc added alloys. However, precipitation free zone (PFZ) also formed in those alloys, where grain boundaries are free from any precipitates. Higher Sc addition was found to hinder the formation of PFZ and α2–precipitates.
Titanium Powder from the TiRO™ Process
Authors: Doblin Christian , Chryss Andrew , Monch Andreas
Published: August 2012

A new continuous process for the direct production of CP titanium powder is being developed at CSIRO. The TiRO™ process has two major steps. The first step is conducted in a fluidised bed where titanium tetrachloride and magnesium powder react to form small (1.5 µm) titanium metal particles uniformly dispersed inside larger spheroidal magnesium chloride particles with an average particle size of 350 µm. The second step involves vacuum distillation in which the magnesium chloride is removed from the titanium. During vacuum distillation the magnesium chloride is volatilised and the micron sized titanium particles come together to form partially sintered predominantly spheroidal porous particles with a similar shape to the starting particle, some which appeared to be hollow. A mechanism for their formation is proposed. The spheroidal particles are all lightly sintered together. The vacuum distilled product was very lightly ground to liberate the spheroidal particles which had an average particle size of about 200 µm. With further grinding an angular Ti powder was produced. The ground titanium was free flowing and had a tap density of 2.4 g/cm3.