bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Supercritical CO2 as an Assistant Method to Optimize the Permeability and Fixation of Nano-TiO2 in PP Non-Woven
Authors: Luo Cheng Wei , Ji Ying Chao , Wang Ying , Yu Zhi Hua
Published: January 2015

In order to solve the difficulty of how nanoTiO2 could penetrate and fixate in polypropylene fiber, the study was carried out by using supercritical CO2 as an assistant method. According to the experiments, the stable nanoTiO2 dispersion could be obtained by the following process. Mixed nanoTiO2, penetrant JFC, polyethylene glycol and ethanol together under the mass ratio of 10:2:1:600, adjusted the pH value to 11, and ultrasonic dispersed for 30mins. Then the PP non-woven fabric was immersed in this solution for 10mins, followed by the treatment with the assistance of supercritical CO2. The optimum process was achieved after three single factor experiments. The reaction time was 40mins, pressure was 30MPa and temperature was 100°C. After treatment, the content of nanoTiO2 in 100g PP non-woven fabric could reach 4.43g, the percentage of the washed residue was 3.42g and the loss rate was 26.3%. nanoTiO2 could penetrate and fixate very well in PP fiber.
Rapid Synthesis of 4-oxo-4H-chromene-3-carboxylic Acid
Authors: Zhu Wu Fu , Tu Yuan Biao , Xu Shan , Tu Qi Dong , Wang Wen Hui , Wang Min , Lei Fei , Xia Hui , Zheng Peng Wu
Published: January 2015

4-Oxo-4H-chromene-3-carboxylic acid (8) is an important intermediate in many biologically active compounds. In this work, a rapid synthetic method for compound 8 was established. The compound 8 was synthesized from the commercially available 1-(2-hydroxyphenyl) ethanone 9 through two steps including vilsmeier reaction and oxidation by Jones reagent. The structure was confirmed by1HNMR and13CNMR spectrum. Furthermore, the synthetic method was optimized.
Preparation of Colloidal Antimony Pentoxide and Synergist Effect on Brominated Flame Retardant
Authors: Lin Li Yun , Zhou Xiang , Wu Ya Rong
Published: January 2015

Colloidal Antimony Pentoxide was prepared through a simple method based on reflux oxidization system. Detailed investigations about the effects of experimental parameters on the colloid stability and size distribution of the final products were carried out. The use of the combination of a brominated flame retardant 2,3-dibromo-succinic anhydride (DBrFR) as the flame-retarding agent and colloidal antimony pentoxide (APO) as the synergist to reduce the flammability of PET/cotton blend fabric was also studied. The BFR was effective in reducing the flammability of the blended fabric whereas APO enhances the effectiveness of DBrFR due to bromine–antimony synergism. The limiting oxygen index (LOI) value and the breaking strength retention of PET/ cotton fabric treated with DBrFR and APO were studied and the thermal behaviors of different treated fabrics were investigated via thermo gravimetric analysis (TGA).
Numerical Simulation for Heat Transfer of Nanofluid in a Rotating Circular Groove Using a Continuous Finite Element Scheme
Authors: Jiang Yong Yue , Lin Ping , Li Bo Tong , Li Lin
Published: January 2015

In this paper, we investigate the heat transfer of the power-law-fluids-based nanofluids in a rotating circular groove. The circular groove rotates with a constant speed and the temperature on the wall of the groove is different from the temperature inside in the initial time. The effects of thermophoresis and Brownian are considered. The thermal conductivity of the nanofluids is taken as a constant. We solve the model with the finite element method directly and discretize them using a continuous finite element scheme in space and a modified midpoint scheme in time. From the results we can find that the heat transfer enhancement of the nanofluids increases as the power law index of the base fluid decreases.
Study on Wettability of Aluminum Alloy Superhydrophobic Surface
Authors: Wu Ruo Mei , Sun Zhao Fei , Chao Guang Hua , Jiang Hai Yun , Lin Wan Tsang
Published: January 2015

Wettability is interfacial phenomena by a solid interface changes from solid-gas interface to solid-liquid interface, and the contact angle is often used to characterize it. The super hydrophobic surfaces with contact angle over 150° have various excellent characteristics. In the paper, the wettability of aluminum alloy surfaces was studied. Based on the Wenzel and Cassie models, the relationship of wettability between roughnesses were investigated on body surface and coating surface. The results indicated that the hydrophobicity of surfaces could greatly enhance with high roughness on surface, and then coating process was analyzed, wettability of aluminum alloys were transformed from hydrophilicity to superhydrophilicity, when they were coated with organic materials with the low surface free energy, such as polypropylene (PP) or maleic anhydride grafted polypropylene (PP-g-MAH), so modified PP can enhanced the hydrophobicity of solid surface mostly.
The Effect of High-Strain Rate on Friction and Wear Behaviors of AZ31 Magnesium Alloy
Authors: He Huan Ju , Zhang Ling Feng , Yang Gen Mei
Published: January 2015

In this study, wear behaviour of AZ31 magnesium alloy shocked by Hopkinson pressure bar was measured, the microstructure morphology was observed and the effect of high strain rate impact on wear resistance and wear mechanism of the alloy were analysed. The results show that: the wear property of AZ31 is improved by the impacted in a reasonable strain rate, but when the strain rate is high enough, it will cause the alloy inactivation. The wear mechanism of the alloy is main grain-abrasion wear, accompanied with the other form of wear, and there will be adhesive wear with the increase of the strain rate.
Investigation on the Formation of Reversed Austenite in QT Treatment
Authors: Yang Yue Hui , Li Jing , Yuan Shao Qiang , Liang Guo Li
Published: January 2015

Microstructures of 9Ni steel quenched at different temperatures were obtained, and a simulated tempering at different temperature was implemented with the DIL850A dilatometer, then the effect of initial microstructure before tempering on the formation of reversed austenite was studied. Results show that the formation of reversed austenite during tempering becomes easier with the decrease of quenching temperature and the increasing of tempering temperature, but the stability may deteriorates with the rapid increasing of reversed austenite in content. Overall, the amount of reversed austenite mainly depends on the tempering temperature, and its formation rate is affected by the quenching temperature because refined quenching microstructure can promote the formation of reversed austenite observably.
Production Process and Heat Transfer Performance of 10/316 Clad Tube
Authors: Yu Zui Xian , Wang Xue Sheng , Chen Qin Zhu
Published: January 2015

A new preparation technique of carbon steel/stainless steel clad tube was introduced, and the contact surface was well combined. Meanwhile, with the using of tube heat exchanger, the experiment on the heat transfer performance of the clad tube was done. Comparing the 10/316 clad tube and the 316 stainless steel tube, the effects on the heat transfer performance of 316 stainless steel tube attached to carbon steel was evaluated. It is showed that overall heat transfer coefficient of 10/316 clad tubes is higher than that of stainless steel tube. The average heat transfer coefficient of 10/316 clad tubes is about 18.7%~34.4% higher than that of stainless steel tube. Experimental investigation indicates that, by brazing and cold drawing, the 10/316 clad tube was well combined and the thermal conductivity was better than that of stainless steel tube.
Lithium-Ion Battery Anode Based on Thinning Si Microchannel Plate Coated with Copper Current Collector
Authors: Hua Qi Qi , Xu Shao Hui , Zhu Yi Ping , Wang Lian Wei
Published: January 2015

In this paper, chemical etched Si microchannel plates (Si-MCPs) is fabricated to use as lithium-ion battery anode. Copper formed by chemical deposition was served as current collector. The chemical etched Si-MCP with copper current collector exhibited a better cycle performance in the galvanostatic charge-discharge measurements. The reaction mechanism was also investigated based on cyclic voltammetry test.
Effect of Sulfuric Acid Diammonium on Cure Characteristics of NR
Authors: Zhang Gui Mei , Jiang Shi Kuan , Zou Jian Yun , Wang Yong Zhou
Published: January 2015

The cure characteristics of NR and constant viscosity natural rubber (CVNR) prepared with sulfuric acid diammonium were studied. The results showed that the relation of dependence of tC10 and tC90 on temperature was as follows: NR>CVNR and CVNR>NR respectively. The sensitivity of tC10 increment to tC90 increment due to increasing of cure temperature followed the rule below: NR>CVNR. The MHo of NR was bigger than that of CVNR.
A Comparative Study between p-Aminobenzensulfonate-Phenol-Formaldehyde Condensate and Sulfomethylated Phenolic Resin as Drilling Mud Fluid Loss Reducer
Authors: Chai Jin Peng , Qiu Zheng Song
Published: January 2015

The p-aminobenzensulfonate-phenol-formaldehyde (APF) condensate is synthesized and characterized by FTIR and TGA analyses. Its properties as drilling mud fluid loss reducer are studied with respect to fluid loss and particle size distribution. In addition, the effect of salt on properties of APF condensate was discussed. Test results show that the APF condensate not only possesses higher thermal stability than sulfomethylated phenolic resin (SMP), a commercial drilling mud additive, but also achieves good property of fluid loss control by reducing the permeability of filter cake; the fluid-loss controlling properties of APF condensate dropped with the increase of concentrations of NaCl.
Interfacial Thermal Resistance and Thermal Rectification in Graphene with Geometric Variations of Doped Nitrogen: A Molecular Dynamics Study
Authors: Shi Jing Hui , Yang Guang , Li Xia Long , Huang Xi
Published: January 2015

Using classical non-equilibrium molecular dynamics simulations (NEMD), the interfacial thermal resistance and thermal rectification of nitrogen-doped zigzag graphene (NDZG) are investigated. Two different structural models about nitrogen-doped graphene are constructed. It is found that the interfacial thermal resistance at the location of nitrogen-doping causes severe reduction in thermal conductivity of the NDZG. Thermal rectification of the triangular single-nitrogen-doped graphene (SNDG) decreases with increasing temperature. However, thermal rectification is not detected in the parallel various–nitrogen-doped graphene (VNDG). These results suggest that SNDG might be a promising structure for thermal device.
Optimal Design on the Roller Hearth Furnace Linings in CSP Plant of WISCO
Authors: Qu Liang , Zhang Mei Jie
Published: January 2015

The heating furnace in CSP plant of WISCO has a lightweight lining which is built by all fiber templates. In light of its good thermal insulation performance and short service life, the lining material for heating furnace was optimized in this article by using heat transfer calculation while the thickness stays light and the insulation performance stays good. The castable was applied to substitute for lightweight fiber materials to prolong the service life of heating furnace lining. Also, this article shows a contrast analysis of heat insulation layer while using different insulation material: the fiber felt, nanoinsulation board and super hydrophobic insulation board. The effect on the temperature of external shell and heat loss was analyzed and discussed. The results generate a new design of material composition, which not only prolongs the service life of heating furnace lining, but also reduces the cost.
Effect of Thermobaric Explosive on Strain Rate
Authors: Zhao Ning Ning , Wang Bo Liang , Li Xi
Published: January 2015

In order to analyze the effect of RDX-based thermobaric explosive on strain rate, the stress-strain curves with different strain rates were measured by using the Split Hopkinson Pressure Bar (SHPB) and resistive strain testing technology. The different strain rates were obtained by changing the length to diameter ratio (L/D=0.46~0.92) and speed of the bullet (10~18m/s). The results showed that it is obvious to change the strain rate by the change of the L/D and speed of the bullet with different functional relationship; RDX-based thermobaric explosives have the evident strain rate: failure stress and strain are increased with the increase of strain rate.
New Algorithm for Engine Oil Identification by Infrared Spectrum
Authors: Shi Yong Gang , Wen Hao , Gong Hai Feng , Li Zi Cun , Su Bin , Sun Ping
Published: January 2015

Based on structure and composition characteristics of engine oil, the new algorithm for its Infrared Spectrum (IR) Identification has been put forward. The Hit Quality Index and Related Hit Quality Index are widely used in Infrared Spectrum Identification recently. The two methods don’t take the importance of the variables into consideration and cannot distinguish the unobvious variation in IR spectra. Therefore the diversity weight factor was introduced into the new algorithm to promote its selectivity. The experimental results had shown that the new spectrum similarity evaluation index could distinguish the unobvious spectrum variations and to improve the infrared spectrum identification capability of engine oils.
EMI-Based Damage Identification for Beam Structures
Authors: Zhang Yu Xiang , Yang Jian Hai , Xu Fu Hou , Chen Jia Zhao
Published: January 2015

A damage identification method is proposed to identify the damage style and the damage parameters. By driving a pair of PZT patches out phase and in phase, the electric admittance of the PZT is obtained. The damage parameters are then identified from the changes of the admittance spectra caused by the appearance of damage. By comparing the identification result, the damage style can be determined and the damage parameters can be obtained. The middle basic particle swarm optimization algorithm is employed as a global search technique to back-calculate the damage. Experiments are carried out on beams. The results demonstrate that the proposed method is able to identify the damage style, and can effectively and reliably locate and quantify the damage in the beam.
Study on the Properties of Wheat Resistant Starch
Authors: Huang Tian Li , Wen Yan Mei , Liu Shu Xing
Published: January 2015

The wheat resistant starch type 3 (RS3) was prepared by the ultrasonic wave-enzyme method. The physicochemical and structure properties of the samples were studied. Results showed that: compared with native wheat starch, the granule structure of RS3 disappeared and the surfaces were awfully rough with obvious folds. Meanwhile the crystal structure appeared intensively showing irregular sheet shape. RS3 lost pasting properties of native starch and enhanced the resistance to enzyme attack. The crystallization structure of RS3 was a mixture of B–type and V–type.
Data Collecting and Identifying Based on Metalloporphyrin and Zinc Phthalocyanine Sensor Array
Authors: Wei Jiao Jiao , Xia Shuang , Qiu Yong Long , Xu Jian Hua , Yang Wen Yao , Xia Man , Zhao Yue Tao
Published: January 2015

Smell-Seeing Sensor Array consists of two parts. One concerns a sensitive arrays, and the other deals with image collecting and processing technologies. In this paper, a 2×2 sensor array is made by the metalloporphyrin (CuTPP、ZnTPP、NiTPP) and zinc phthalocyanine (ZnPC). Exposed in vapor of 14 different kinds of VOCs (Volatile Organic Compounds) at room temperature, the array appears color change. ARM-Linux system and OpenCV are used to collect and process the color change. This system could detect 14 kinds of VOCs, achieving visualization of gas sensor detection, and laying a foundation of further qualitative identification of VOCs.
Boron-Doped Ultra/Nanocrystalline Diamond Films Obtained with Different Growth Times and Boron Doping Levels
Authors: Santos Marta , Azevedo A.F. , Souza F.A. , Baldan M.R. , Ferreira N.G.
Published: January 2015

In this work, the achievement and characterization of boron-doped nanocrystalline diamond films is presented. A series of experiments varying boron doping levels from 2,000 to 30,000 ppm and film growth times during 6, 10 and 16 h were performed. These films were analyzed by Scanning Electron Microscoy (SEM), Atomic Force Microscopy (AFM), Raman spectroscopy and Cyclic Voltammetry (CV) measurements. The results showed that the films presented two morphologies: ultra and nanocrystalline diamond. From Raman spectroscopy, the doping level increase for all the films, independent of growth time, increased the boron acceptor number and it was confirmed by Mott-Schottky plot (MSP). Electrochemical response showed the influence of boron content in the work potential window, mainly for films grown during 6 h. However, the reversibility was almost independent on the boron content for samples grown during 16 h.
Investigation of Boron Doped Nanocrystalline Diamond Films Grown on Porous Silicon Substrate under Different Doping Concentrations
Authors: da Silva Lilian Mieko , dos Santos Marta , Azevedo Adriana Faria , Baldan Maurício Ribeiro , Beloto Antonio Fernando , Ferreira Neidenêi Gomes
Published: January 2015

The production and characterization of porous silicon (PS) samples were studied as well as their use as substrates to grow boron doped nanocrystalline diamond (NCD) films. PS represents a suitable material for diamond growth due to its large number of nucleation sites and surface area, becoming an excellent material for porous electrodes. NCD films were grown by chemical vapor deposition (CVD) technique by balancing H2/CH4/Ar gas mixture, at two different boron levels. Doping was conducted by an additional hydrogen line passing through a bubbler containing B2O3 dissolved in methanol. Two ratios of boron/carbon were used of 2000 and 20000 ppm in the bubbler solution. Scanning electron microscopy, Raman spectroscopy and X-ray diffraction were used to characterize the films as well as the PS substrate. Results showed that it is possible to obtain NCD films on PS substrate with good quality at different doping levels.
Evaluation of the Deposition of Nanoparticles in Fibrous Filter
Authors: de Barros Priscila Martins , Rodrigues Cirqueira Samirys Sara , Lopes Aguiar Mônica
Published: January 2015

This study aimed to evaluate the deposition of NaCl nanoparticles during filtration in a cellulose filter medium (HEPA). The diameter of the generated polydisperse particles was between 6 and 800nm. Deposition was evaluated with the curves of pressure drop as a function of time. The permeability of the filter medium was determined and, after the deposition of particles, specific resistance of the formed cake was obtained. Filter performance was evaluated by counting particles before and after the filter medium and the pressure drop was monitored in order to obtain the filtration curve. Filtration velocity was kept at 0.06 m/s, and the concentration of the solution generated at a rate of 0.0042 L /min in a commercial inhaler was of 5 g/L. The results showed that this filter showed two steps during the deposition of particles, an internal filtration stage and a surface filtration stage. Although this filter is highly efficient in removing particles in the range evaluated, roughly 100%, particle penetration was observed in the range between 50 and 200nm.
Characterization of Nitrogen Doped Diamond Electrodes Produced by Hot Filament Chemical Vapor Deposition
Authors: Santos Nazir M. , Arantes Tatiane M. , Ferreira Neidênei G. , Baldan Mauricio R.
Published: January 2015

The purpose of this work is to study the structural and morphological modification of the surface of the n-type diamond electrodes as a function of nitrogen doping. The characterizations of these electrodes were made using Raman Spectroscopy, Contact Angle, X-ray diffraction and Scanning Electron Microscopy (SEM). The nitrogen-doped diamond (NDD) electrodes were produced using Hot Filament-assisted Chemical Vapor Deposition method (HFCVD) from methane, hydrogen and nitrogen in the gas mixture. The results from Raman spectroscopy show that the diamond films obtained with nitrogen addition presented one large band at 1100-1700 cm-1. The SEM images showed that the variation in the nitrogen doping influenced the growth rate of films by promoting changes in the sizes of grains from microcrystalline to nanocrystalline texture. This behavior supported the results obtained from X-ray diffraction analyses. It was possible to verify a decrease in the crystallite size as a function of the nitrogen increase.
Vertically Aligned Carbon Nanotubes/Carbon Fiber Composites for Electrochemical Applications
Authors: Saito Eduardo , Caetano Vagner Eduardo , Antunes Erica Freire , Lobo Anderson Oliveira , Marciano Fernanda Roberto , Trava-Airoldi Vladimir Jesus , Corat Evaldo José
Published: January 2015

Carbon fibers have been studied for electrochemical applications. Recently, carbon nanotubes present a wide potential uses in electric, mechanic, electrochemical and materials science field. At present study, vertically aligned carbon nanotubes were produced over carbon fibers. The process occurs catalytically by chemical vapor deposition (CVD) using mixture with camphor and ferrocene. After that, the VACNT/CF composite are treated by oxygen plasma for oxygen functionalization. Prior the electrochemical analysis, CNT/Carbon fibers are treated by hydrochloric acid to remove residual catalyst. The electrodes were tested in a usual electrolyte (with H2SO4 0.5M) in a conventional electrochemical cell. The specific capacitance was tested in a separate device. The configuration of carbon fibers and VACNT presents a high potential application for electro analytical application and energy storage.
Analysis of the Effect of the Underflow Orifice Size on the Filtering and Concentrating Hydrocyclone
Authors: Silva N.K.G. , Salvador Fernanda Falqueto , Vieira L.G.M. , Barrozo Marcos A.S.
Published: January 2015

Hydrocyclones are equipments widely used in solid-liquid separation, as in mineral, chemical, petrochemical, textile, and metallurgical industries. The suitable choice of its dimensions depends on the process main objective. There is the case that the major interest is to concentrate a suspension, either to discard the dispersed phase (solids) or to use it. The objective of this work was to study, experimentally, a filtering hydrocyclone with a suitable geometry that provides a low underflow-to-throughput ratio, i.e., that produces a thick underflow. The effect of the underflow orifice diameter in the equipment performance was evaluated. The results showed that the smallest orifice size produced an underflow stream with concentration upper than 45% in volume.
Effect of Mechanical Alloying on Characteristic of Powders of Amnoia Hepatamolybdate, Copper and MoCu Sintered
Authors: Silva Ronyclei Raimundo , Resende Leonardo , Assunção Rodolfo Albuquerque Buarque , Costa Franciné Alves , Gomes Uílame Umbelino
Published: January 2015

The mechanical alloying of Mo-Cu powders allows the production of highly homogeneous sintered pieces, with very thin Mo particles and good dispersion of Mo particles in the ductile Cu phase, allowing the development of a route for the preparation of Mo-Cu simple composite powders, environmentally sustainable and able to increase the sinterability of the material without causing damage to their properties of thermal conductivity and electrical. Was used the precursor powders of molybdenum (Ammonium heptamolybdate) plus Cu, where two samples were prepared by mixing processes. For mechanical alloying, and by mixing manually, and both reduced and sintered in a resistive furnace with hydrogen gas. The materials were analyzed by optical microscopy, XRD and density measurements. The results confirm the effect of mechanical alloying on the increasing in high density of the sintered samples and thereby producing superior properties to those shown by the mixing manually sample.
Obtaining Constitutive Equations for Thickening and Filtration Non-Newtonian Fluids
Authors: de Oliveira Helio , Moreira Bruno Arantes , Damasceno João Jorge Ribeiro , Arouca Fabio de Oliveira
Published: January 2015

The study of filtration and thickening of particulate systems are used in many industrial processes involving processes of solid-liquid separation, such as in sedimentation ponds, filters, the drilling of oil wells, among others. This paper aims to advance the empirical mechanisms involved in the processes of solid-liquid separation and obtain constitutive equations relating the pressure in solids and porous media permeability from non-Newtonian fluids. In the experiments used aqueous solutions of xanthan gum concentration of 0.1% in weight basis in order to ensure non-newtonian means. For the preparation of suspensions, was used calcium carbonate as particulate material in the separation process involved an initial concentration of 12% by volume. The concentrated sediment was maintained between 30 and 48% by volume. Settling tests were carried to term and sediments resulting from each test were evaluated by making use of the Gamma Rays Attenuation Technique (GRAT). The results show that GRAT is effective in determining sediment concentration distributions formed from non-Newtonian solutions, allowing the constitutive equations to obtain pressure and the solid porous medium permeability, very important for simulations of solid-liquid separation processes.
Analysis of the Compressibility of Sediments in Batch Settling Tests Using Newtonian and Non-Newtonian Fluids
Authors: Moreira Bruno Arantes , de Oliveira Hélio , Arouca Fábio de Oliveira , Damasceno João Jorge Ribeiro
Published: January 2015

The study of compressibility in deformable porous media is of interest in many industrial processes, such as, filtration, thickening and during oil well drilling processes in the petrochemical sector. In this work the compressibility of porous media was evaluated by the comparison of solid concentration profiles in sediments using fluids with Newtonian and non-Newtonian behavior. For this, consolidation tests in distillated water, solutions of xanthan and glycerol were performed in a vertical column from the gravitational settling of suspensions. The porosity distribution in the formed sediment was obtained after the complete settling of particulate material. The local porosity measurements were performed using the ionizing radiation emitted by americium-241. The gamma-ray attenuation technique used in this study allowed the realization of nondestructive measurements for achieving local concentration of solids. The results showed that the rheological behavior of the fluid does not change significantly the compressibility of the porous matrix.
Fe-hBN Composites Produced by Double Pressing and Double Sintering
Authors: Hammes Gisele , da Costa Gonçalves Priscila , Binder Cristiano , Furlan Kaline Pagnan , Klein Aloisio Nelmo
Published: January 2015

In order to develop a composite for future applications as self-lubricating material, samples with iron matrix and contents of hexagonal boron nitride (hBN) of 0, 2.5, 5, 7.5 and 10 vol%. were produced by conventional powder metallurgy, varying the compacting pressures. It was observed a decrease of mixture flowability and apparent density when increasing hBN content. Moreover, the samples showed an increment of green densification with the increase of applied pressures and hBN contents, suggesting that hBN particles accommodate into the voids during pressing. As known, hBN has low shear strength and is insoluble in the iron matrix, which hinder the formation of necks between the particles of iron during sintering. To improve matrix continuity the double pressing technique was used, and this technique presented increments of 3 to 5% of densification and up to 95% of tensile strength when compared with the composites produced by single pressing.
Characterization of Commercial Co-Cr-Alloy Powder Used in Selective Laser Sintering
Authors: dos Santos Claudinei , da Silva Paula Cipriano , de Paula Luciane Carvalho , Habibe Alexandre Fernandes , Lins Jefferson Fabrício Cardoso , Soares Walter
Published: January 2015

This paper presents the microstructural characterization of particle systems used in equipment for selective laser sintering. Three distinct commercial metal powders, with chemical composition based on Co-Cr-alloy, were characterized by X-ray diffraction, scanning electron microscopy and particle size distribution. The powders showed regular spherical particles with varying sizes and crystalline phase of Co-solid solution. Different powders present particle size among 55nm and 245 nm. This behavior affects the sinterability of samples submitted to the selective laser sintering.
Performance Thermally Sprayed Coatings Tests when Subject to Adhesive Wear
Authors: Arnt A.B.C. , da Rocha M.R. , Marangoni G.F.
Published: January 2015

In this study it was evaluated the performance of coatings based on Cr3C2-25 (80Ni-20Cr) and CrC-30NiCr. The coatings were deposited by high velocity oxygen fuel (HVOF), with an average thickness of layer equal to 7.8μm. Samples were subjected to adhesive wear test (according ASTM G99) with a pin Ø 6 mm (SAE 52100). In the test was applied normal force equal to 50 N and tangential speed equal to 0.5 m/s. The test time was 30 minutes at room temperature, without lubrification. The wear surfaces were characterized by optical microscopy, scanning electron microscopy and X-ray diffraction. The microhardness of the coatings was also evaluated. The results showed that the coating based on Cr3C2-25(80Ni-20Cr) presented a performance ten times higher in wear resistance when compared to coating CrC-30NiCr.
Thermal Treatment and Improvement of Tribologycal Properties of Automotive Ring by Laser Methods
Authors: de Oliveira Helder Souza , Santos Claudio Luis , Teleginski Viviane , Vasconcelos Getúlio
Published: January 2015

This work presents the results of treatments by CO2 laser of automotive rings covered with carbon black slurry, aiming to improve the friction rate and the ring lifetime. The results of this treatment were characterized by scanning electron microscopy, Vickers hardness, ball on disk test and X-ray energy dispersive spectroscopy. The scanning electron microscopy showed that the laser treated area extent reaches near to 120 μm depth. The measured hardness was about 950 HV0,05 and the friction coefficient lower than 0.2. The energy dispersive spectroscopy along the treated cross section showing carbon diffusion into the metallic substrate.
Influence of Temperature on Ductile-Fragile Behavior
Authors: Silva C.A. , Nascimento R.C.R. , Martins M.S. , Freitas M.C.S.
Published: January 2015

The article to be presented will cover the whole process done in a fracture test for impact, taking into account the thermal treatment of the sample to be studied. The main objective of this article is to observe, verify, analyze and understand how the temperature difference of several samples influences the type and appearance of the fracture. The impact test have a great importance in industry, is through this that you can verify that the material is ideal for application in the production of equipment and vehicles that operate in high or low temperatures. The evaluation criteria of this trial are the energy absorbed by the sample, and the percentage of its characteristic lateral extension, and the percentage of fracture, ductile or fragile, and corresponding to a ductile fracture mode, in which the test at higher temperatures, the impact energy is relatively large, and fragile fracture mode, being one that as the temperature decreased, the impact energy will suffer decline. The most important result of the impact test is the measure of the energy absorbed by the test body to deform and break, measured by the variance of the gravitational potential energy of the hammer (machine component of the impact test) before and after impact. Therefore, providing the conclusion that the smaller the energy absorbed by the sample, more fragile it is depending on the temperature applied.
Adherence Analysis of DLC Films Grown on AISI M2 Steel Substrates as a Function of Silicon Interlayer Thickness
Authors: da Silva Patrícia Cristiane Santana , Martins Gislene Valdete , Pereira Lania Auxiliadora , Corat Evaldo José , Trava-Airoldi Vladimir Jesus
Published: January 2015

Diamond-like carbon (DLC) films are widely known for their attractive properties. High adhesion between coating and substrate is necessary to ensure these properties. The bombardment by energetic species during growth tends to generate high intrinsic compressive stresses levels, which have several consequences in coating performance. However, this problem can be solved with the deposition of a thin interlayer with intermediary properties. In this work, films were grown on M2 steel using a modified plasma enhanced chemical vapor deposition PECVD pulsed-DC discharge. In order to improve the coating adherence on the substrate, a silicon interlayer was deposited varying the growth time, which generated different interlayer thickness. Tribological tests were performed to study adhesion and friction gradient. Raman spectroscopy was used to verify the structural arrangement of carbon atoms. The results showed that thickness variation in silicon interlayer leads to significative changes in adhesion between coating and substrate.
Study of Sintering of Iron Powder Bars Processed by Equal Channel Angular Pressing
Authors: Ribeiro Mônica Paula , Hupalo Marcio Ferreira , Vurobi Selauco , Cintho Osvaldo Mitsuyuki
Published: January 2015

The main aim of this work is to show porosity evolution during application of various processing conditions to a high-purity (99.7 wt.%) iron powder, including compacting, sintering and equal channel angular pressing (ECAP). Iron powder bars with dimensions of 8x8x30 mm and 8x8x10 mm were axially pressed with pressures ranging from 100MPa to 250MPa, followed by sintering at 1100oC during 30 minutes under argon atmosphere. Sintered bars were processed by ECAP at room temperature in a single pass, using a SAE 1045 steel die with an internal angle of 120o. Microstructural characterization was performed by light optical microscopy (LOM) and quantitative stereology. ECAP processing resulted in a substantial reduction in the porosity levels for specimens pressed at 100 MPa and 150 MPa. The sample compacted with 150MPa and processed by ECAP with back-pressure showed the lowest volume fraction of porosity. Higher compacting pressures caused an increase in porosity levels. This result is explained by presence of cracks prior to ECAP and the concurrent action of severe stress-strain states during extrusion.
Comparative Study of Mechanical Activation Improved by High Energy Ball Mills in Chromium Oxide Reduction
Authors: de Castro Mauricio , Cintho Osvaldo Mitsuyuki , Capocchi José Deodoro Trani
Published: January 2015

The processes of high-energy milling and gained importance among the unconventional methods. In this work, we seek to compare the power supply two types of high energy mills (vibratory mill (SPEX) and planetary mill) with the variation of the milling power. The millings were carried out with a mixture of chromium oxide and aluminum metalic. The reduction of chromium oxide does not occur instantaneously, but gradually as the progress of milling with mechanical activation of powders, this mechanical activation occurs leading to the solid state reaction occurs. The results were obtained for thermal analysis of the samples. The energy released varies, exhibiting a maximum mechanical activation for the range of powers milling studied. The correlation between the energy mills can be made by identifying the milling power is reached at which the maximum in each mechanical activation mill and quantifying this activation.
Self-Discharge and Microstructure of Supercapacitors Tested at Room Temperature and at 333 K
Authors: Spena Visentini Virgilio Russo , Carlotti Zarpelon Lia Maria , Faria Jr Rubens Nunes
Published: January 2015

The microstructure, chemical composition and self-discharge of some retail available supercapacitors have been investigated. Standard capacities of 1.0, 0.47 and 0.1 F at a maximum potential of 5.5 V were employed in this study. Self-discharge were carried out at room temperature and close to the nominal maximum working temperature of the supercapacitors (specified for 343 K). Internal resistance of the supercapacitors were calculated using the discharge curve for room temperature and 333 K. The microstructures of the electrode powder material have been investigated using scanning electron microscopy (SEM) and chemical microanalyses employing energy dispersive X-ray analysis (EDX). A compositional and morphological evaluation of these commercial supercapacitors materials has been carried out.
Effect of Plasma Nitriding on Creep Behavior at 550 °C of a Maraging Steel (300 Grade) Solution Annealed
Authors: dos Reis Adriano Gonçalves , Reis Danieli Aparecida Pereira , Abdalla Antônio Jorge , Otubo Jorge
Published: January 2015

The objective of this work is to evaluate creep behavior of a maraging steel (300 grade) solution annealed before and after superficial treatment of plasma nitriding. Creep tests were conducted on a standard creep machine at stress range of 200 to 500 MPa at 550°C. Samples with a gage length of 18.5 mm and a diameter of 3.0 mm were used for all tests. Creep parameters are determined and a comparative analysis is established with the results gotten from the alloy with and without plasma nitriding. Maraging 300 steel plasma nitrided has showed a similar creep behavior compared with the same alloy without superficial treatment, with creep rate and stress exponent results very close to the material only solution annealed. This result can be associated with the strong impact of reversion of martensite to austenite and overaging at this temperature and time of exposure that minimizes the benefits of a superficial treatment.
Comparative Study of Creep Resistance of a Ti-6Al-4V Alloy with Metallic and Ceramic Coatings
Authors: Briguente Flávio Perpétuo , da Silva Briguente Luciana Aparecida Narciso , Reis Danieli Aparecida Pereira , da Silva Maria Margareth
Published: January 2015

Titanium and its alloys are largely used for many industrial applications due to their high mechanical and corrosion resistance and low specific mass. Ti-6Al-4V alloy is the most used in aerospace industry and it is applied for the manufacturing of aircraft blades and steam turbines. This alloy has high affinity with oxygen which constrains its application at high temperatures due to creep resistance reduction. Methods to increase creep resistance of Ti-6Al-4V alloys includes the use of metallic coatings and its combination with ceramic thermal barrier coating deposition on the material surface. The aim of this work is to compare the creep behavior of Ti-6Al-4V alloy in three different conditions: uncoated, metallic coated, metallic + ceramic coated specimens. The metallic coating layer (CoNiCrAlY) and the ceramic coating (ZrO2 + 8wt%Y2O3) are both applied by plasma spray deposition technique. The specimens were submitted to constant load creep tests at 600oC and stress conditions of 125, 250 and 319MPa. Specimens of metallic + ceramic coating have presented higher creep resistance, longer lifetime and lower stationary creep rate when compared to uncoated and metallic coated specimens.
Influence of High Temperature Sintering on Impact Properties of Low Alloyed Steels
Authors: Menapace C. , Cipolloni G. , Molinari A.
Published: January 2015

High temperature sintering, i.e. at temperatures above 1150°C is a well-known concept in industry. For example in the metal injection molding (MIM) process sintering temperatures employed are higher than 1250°C for ferrous alloys [1]. The advantages of this technology respect to conventional sintering are many: an increase in the homogeneity and in density, a better pores morphology, the elimination of some reducible oxides. All these lead to better mechanical properties and corrosion resistance which means better performance [2, 3, 4, 5].
Chemical, Structural and Mechanical Study of Metallic Biomaterials Used in Hip Arthroplasty
Authors: Filho Francisco Pinto , da Silva Morais Crislene Rodrigues , de Campos Karla Valéria Miranda , da Silva Nascimento José Jefferson , da Silva Burit Josué
Published: January 2015

Arthroplasty is a surgery that aims to replace the defective joint surfaces, aiming to restore their functions. Is employed in this type of surgery that metallic materials play a key role in the constitution of orthopedic prostheses. In this context, we studied the chemical composition, mechanical and structural behavior of stainless steel developed for applications as biomaterials used in the manufacture of orthopedic implants. In this paper, two prostheses were analyzed established brands in the market. Proceeded through the chemical Spectroscopy Energy Dispersive X-ray (EDX) analysis. Characterized the crystal structures of these materials by diffraction of X-ray and mechanical behavior using tensile test. We compared the results of chemical composition and strength of the samples according to ASTM F-138 (2008). The results of EDX showed the presence of chloride in stainless steel alloys as an impurity that can compromise the durability of the prosthesis. The XRD patterns showed the presence in austenitic stainless steel alloys. As the tensile strength of the alloys analyzed, values that are consistent with those presented in the standards were recorded. In a general analysis, it became apparent incompatibility of assessed as biomaterials for use in prosthetic alloys, although meets the structural and mechanical requirements.
Effects of Order-Disorder Reactions on the Magnetic Properties of Rapidly Quenched Fe-6.5% Si Alloy
Authors: Nascimento F.A. , da Silva M.C.A.
Published: January 2015

Deposits of the Fe-6.5wt%Si alloy rapidly quenched by spray forming were investigated. The order phase can be either B2 or DO3 depending on annealing treatment conditions. The observation of pairs dislocations indicates the presence of super dislocations and B2 antiphase boundaries (APBs) which affects significantly the soft magnetic properties. The dislocations bound the APBS which yield δ fringes when image 200 superlattice reflections. Samples treated at 700oC for 1 h were oil quenched, this has induced a decreasing of power loss and the TEM micrographs have showed developed 1⁄4 <111> antiphase domain structure in the B2 phase. The magnetic properties were: power loss of 1.59 W/kg and coercive force of 76 A/m, at B=1 T, f=60 Hz. The samples annealed at 1250°C for 1h showed the same interaction between the APBs but better power losses on their magnetic properties. The magnetic properties were: 1.30 W/kg power loss and 40 A/m coercive force, at same conditions described above. This suggests a strong interaction between magnetic properties and antiphase domain structure in the B2 ordered phase. Optical microscopy observations corroborate the magnetic measurement conclusions.
Sintering of Al4C3 Using Aluminum Scrap and Commercial Graphite
Authors: Coelho Rodrigo Estevam , Silvany D.B. , Sobral M.D.C. , Silva M.C.A.
Published: January 2015

In this works, aluminum scraps powders were mixed with commercial graphite and mechanically alloyed in a high-energy ball mill and subsequently powders sintering. The initial grinding of aluminum scraps for 2 hours and then mixed with commercial graphite powder at a proportion of (y)Al-(x)C (wt%) (x = 1, 5 e 10, 25). The mixture of aluminum and graphite powders was processed for a time at 5 hours of milling. The samples were sintered at a temperature of 750°C and 1000°C. Samples were analyzed by scanning electron microscopy and X-ray diffraction. The results of this study were to find important parameters of composition and sintering, because the increase in concentration of carbon in the aluminum indicates that the material may have different applications.
Electrochemical Hydrogen in Metals - Can we Effectively Control this Harm?
Authors: Beloglazov Sergei M. , Beloglazov Georgii S.
Published: January 2015

The problem under consideration concerns the prevention of absorption of hydrogen in the processes of corrosion and electroplating of all industrially used metals with the aim of the modification of chemical and physical properties of base metal surface. Its properties change towards better brightness and soldering, minimal porosity and hydrophilicity of surface, increase of hardness and wear resistance. All these properties were evaluated by means of appropriate test equipment. Residual stresses in Cr coating by phase transformation, beginning in the electroplating process, acted in combination with absorbed huge quantity of hydrogen in intrinsic defects in the steel base. Internal stresses in the base/coating region resulted in severe deterioration of the durability of steel parts, as identified by static or sign-variable fatigue tests. The newstress-steptechnique makes possible an analysis of H content as a function of the depth in base metals and its distribution in coating metal .
Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition
Authors: Chmiel Jarosław , Baranowska Jolanta , Jędrzejewski Roman , Rzeczycki Arkadiusz
Published: January 2015

Cavitation attack in liquids generated a various states of stresses in surface layers of metals. Differences in stress state effects on hydrogen absorption activated by the cavitation implosion. Results of XRD investigation and FEM modeling shows on inhomogenity of process.
Physico-Mechanical Wear Processes of Cell Guides in Container Ships - Phenomenology
Authors: Szyszko Małgorzata
Published: January 2015

The article presents the phenomenology of problems of cell guides container ships wear processes. In the paper the issues of tribological and nontribological types of wear processes. Presented problems regard to the analysis of exposures that cause wear in the carriage by sea and in the process of containers handling at the maritime port.
Hydrogen Influence on Electrochemical Properties of Gallium Monoselenide
Authors: Balitskii Olexiy , Eliasz Jacek , Kvashnivska Nataliia , Polishchuk Nataliia , Gryshchenko Sergiy
Published: January 2015

It is experimentally established that illumination of GaSe (Pb) hydrogen saturated layered semiconductor electrodes in acids (H2SeO3, H2SO4) and neutral (water) environments has improved the anode and cathode reactions.The influence of H2SeO3 solution on the potential of open circuit and current density is different for crystals in initial state and after hydrogenation. During the sunlight irradiation, polarization takes place at the low values of current density and more positive value of potentials in comparison with the result obtained in darkness. Taking into account the results, obtained also in the acid H2SO4 environments, we have established that anode and cathode reactions have a slower character and run at the more negative potential values in comparison with the neutral environment.
Effect of Nanostructurisation of Structural Steels on its Wear Resistance and Hydrogen Embittlement Resistance
Authors: Nykyforchyn Hryhoriy , Kyryliv Volodymyr , Maksymiv Olga
Published: January 2015

Surface mechanical pulse treatment of medium-carbon low alloyed steels by high speed friction has been developed. Its major features are surfaces provided with the nanostructure with grain size of 20...50 nm, increased surface hardness and, correspondingly wear resistance. This nanostructure is subjected to the tempering temperature of 500 °С. Hydrogen charging of the strengthening materials decreases their plasticity, more considerably in steels with higher carbon content. However, it is possible to use mechanical pulse treatment to achieve high characteristics of strength, wear resistance and plasticity in hydrogen, selecting as-received matrix structure and the tempering temperature after surface treatment.