bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure Homogeneity, Crack Propagation and Self-Toughening of Solidified TiC-TiB2 Composite Prepared by Combustion Synthesis in Enhanced High-Gravity Field
Authors: Song Ya Lin , Zhao Zhong Min , Zhang Long , Wang Shuan Jie
Published: November 2013

A series of solidified TiC-TiB2were prepared by combustion synthesis in enhanced high-gravity field, and the ceramics were comprised of TiB2primary phases, irregular TiC secondary phases, a few of Al2O3inclusions and Cr-based metallic phases. Because of the accelerated phase separation of Al2O3droplets from the molten reaction products, the enhanced high-gravity field not only caused both Al2O3inclusions and shrinkage cavities to be sharply reduced, but also brought about the refined microstructure and the improved homogeneity in the solidified ceramic. As high gravity acceleration reached 2500 g, the ultrafine-grained microstructure with the thickness of TiB2platelets smaller than 1 μm was achieved, and FESEM fractographs showed a whole of ultrafine TiB2platelets almost accomplished the pullout process, and the maximum fracture toughness of 16.5 ± 1.0 MP · m0.5was achieved, whereas the maximum flexural strength of 982 ± 20 MPa was also simultaneously obtained as a coupled result of sharply-reduced defects, the refined microstructure, the improved homogeneity and the high defect tolerance achieved in the near-full-density composite.
Study on Process and Properties of Needling Silica Fiber Reinforced Silica Composites
Authors: Wei Qi Hong , Wang Chong Hai , Wang Hong Sheng , Li Ling , Shao Chang Tao , Dong Bo
Published: November 2013

With the development of military weapons, the demand of weapons is growing. But now 2.5 D silica fiber reinforced silica composites have long production period, high cost,which limited the production and schedule of weapons. This paper studied low cost manufacturing technology from two aspects of fiber preform weaving mode and molding process. The preforms were prepared with needling process.CT images of needling preform, thermophysical properties and mechanical properties and dielectric properties of needling silica fiber reinforced silica composites were studied inthis paper.The results showed that needling SiO2f/SiO2 composites had short production period and low cost, which had good mechanical properties.Tensile strength was 20.1MPa, compressive strength of XY direction was 88.3MPa,bending strength was 52.2MPa. Dielectric contant was less than 3.05 and dielectric loss was less than 8×10-3.
Pore Structure and Mechanical Properties of ZrC/SiC Multi-Components Modified C/C Composites
Authors: Li Xiu Qian , Qiu Hai Peng , Jiao Jian
Published: November 2013

The ZrC/SiC multi-components modified C/C composites were prepared by using a hybrid precursor containning polycarbosilane and organic zirconium-contained polymeric precursor as impregnant and C/C composites of low density as preform. The porosity, microstructure and mechanical properties of samples were characterized with mercury injection apparatus, scanning electron microscopy and universal electron testing machine respectively. The results show that the porosity and average pore diameter decrease firstly and increase subsequently with the increase of organic zirconium content of the precursor. When the content of organic zirconium is 50%, the porosity and average pore diameter reach minimum which were7.27% and 0.0795um respectively. The most probabilistic pore diameter shifted from 10-100um to 1-10um at the same time; Meanwhile, the flexural properties also increases and drops immediately as the content of organic zirconium in the precursor adds. When the content of organic zirconium is 25%, the flexural strength reaches maximum of 245.20MPa.The improved flexural properties is attributed to the proper bonding of fiber-matrix interface and the low porosity of samples.
Electrical Characterization and Microstructures of Bi4-xTmxTi3O12 Ceramics
Authors: Li Bei , Yuan X.H. , Chen M. , Mei X.A.
Published: November 2013

Tm-doped bismuth titanate (Bi4-xTmxTi3O12: BTT) and pure Bi4Ti3O12 (BIT) ceramics with random orientation were fabricated by a conventional electroceramic technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed plate-like grains with random orientation. Tm-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675 °C to lower temperature and a improvement in dielectric property. The experimental results indicated that Tm doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BTT ceramic with x=0.75 were 16 μC/cm2 and 75 kV/cm, respectively.
Comparative Measurement on Transmittance of Four Systems of Dental All-Ceramic Zirconia Materials
Authors: Deng Bin , Xu Juan , Shi Guang , Liang Li Min , Yi Yuan Fu , Shao Long Quan , Wen Ning , Gu Bin , Liu Yi Han , Chen Ji Hua
Published: November 2013

This study aims to investigate the difference on transmittance of four systems of dental all-ceramic zirconia materials which are at clinical required thickness,IPS e.max Press used as control.All-ceramic zirconia specimens containing Zenostar,Lava,Cercon and Upcera,are fabricated into discs with 10mm in diameter and 0.5±0.01mm in thickness.The transmittance of disc specimens are measured by using PR2650 spectrophotometer and the measurements are conducted statistical analysis with software SPSS13.Experimental results reveal that the transmittances of four systems of zirconia materials are significantly different.Their transmittances decrease in sequence of IPS e.max Press ,Zenostar,Lava,Cercon and Upcera zirconia.Zenostar and Lava Zirconia,which have good optical effects,possess ideal restorative materials for anterior teeth with higher transmittance.
Effect of ZrO2 Coating on the Properties of Porous Silicon Nitride
Authors: Liao Rong , Wang Hong Sheng , Wang Chong Hai , Zhou Chang Lin , Liu Jian , Wei Qi Hon
Published: November 2013

The powder of 3molY2O3-ZrO2 as the coating material sprayed on the surface of porous silicon nitride which porosity is more than 50% by Plasma Sprayed. The microstructure of the coating and the matrix was analysised. The performance change of porosity, strength and insulation, before and after spray, were researched.
A Review of Coating Preparing Techniques of Bioactive Glass
Authors: Chen Chuan Zhong , Meng Xiang Guo , Yu Hui Jun , Yang Han , He Ting , Wang Dian Gang , Zhao Shi Gui
Published: November 2013

Bioactive glass, because of the good bioactivity and biocompatibility, is considered to be the most ideal material for bone repair and replacement. However, the mechanical properties of the bioactive glass are great different from that of human bone. Coating bioactive glass on the surface of Ti or Ti-alloys that possess excellent mechanical properties can offset the disadvantage. In this paper, the research progress in the coating preparing techniques such as enameling, sol-gel, electrophoretic deposition, plasma spraying and pulsed laser deposition is summarized, the advantages and existent problems of the coating preparation techniques are discussed, and the development foreground is forecast.
Ferroelectric Characterization and Microstructures of Bi4-xLuxTi3O12 Ceramics
Authors: Mei X.A. , Chen Min , Huang C.Q. , Liu R.F.
Published: November 2013

Ferroelectric electrical properties of Lu2O3-doped bismuth titanate,Bi4-xLuxTi3O12 (BLT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all samples. SEM micrographs showed randomly oriented and plate-like morphology. For the samples with x=0.25 and 0.75 P-E hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.5 and 0.75 P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr ) and coercive field (Ec) of the BLT ceramic with x=0.75 were above 18μC/cm2 and 85KV/cm , respectively.
Phase Transformation of Diatomite during Magnesiothermic Reduction Process
Authors: Liu Shu Yue , Fang Ming Hao , Huang Zhao Hui , Ji Hai Peng , Min Xin , Liu Yan Gai , Wu Xiao Wen
Published: November 2013

In this study the phase behavior of diatomite during magnesiothermic reduction process was investigated. Two packing routes were adopted to estimate the reduction effectiveness at a low reaction temperature of 650 °C for 2h. The phase and microstructure evolution of diatomite were investigated by XRD, SEM, EDS. The results show that diatomite was sucessessfully reduced by the magnesium vapor and reaction products were Si, MgO, and Mg2Si when the raw diatomite was blended with Mg powder. Mg2Si and MgO were alternatively and incompletely dissolved after being immersed in a 1 M HCl solution for 6 h. Meanwhile, the reactant molar ratio had an important influence on products when the raw diatomite was separated with the Mg powder. A small amount of diatomite was reacted to generate MgO and Mg2Si as the molar ratio of Mg and diatomite was 2:1. By contrast, with the molar ratio increasing to be 10:1, diatomite was completely reacted to be Mg2Si and MgO.
Preparation and Performance of Titanium Matrix Anodized Oxide Coating Anode Ru-Ir-Ti/Ti
Authors: Su Lin , Hu Jin , Wang Yu Tian , Zhang Wei Jun , Li Ying
Published: November 2013

In this study, modification of the anodizing titanium substrate surface will be used to prepare titanium oxide films that have a porous structure. A Ru-Ir-Ti/Ti anode oxide coating was prepared by the Pechini method. The microstructure of the coating is observed by scanning electronic microscope (SEM). The phase of the coating is analyzed by X-ray diffraction. The electrochemical properties of the coating are studied by Energy Dispersive X-ray (EDX) and the tests of polarization curves, cyclic voltammetry and strengthen electrolysis life. The results show that titanium oxide film prepared by anodic oxidation owns porous morphology and the chlorine release of the anode coating is less active, while the electro-catalytic activity of this coating is slightly better than non-anodized anodic coating. Its strengthening electrolysis life is also poor.
Hot Deformation Behaviors of SiCp/2024 Aluminum Composites
Authors: Hao Shi Ming , Xie Jing Pei
Published: November 2013

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500 °C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 153.251 kJ/mol. The optimum hot working conditions for this material are suggested.
Preparation and Magnetic Property of Carbon Nanotube/NiZnCo Ferrite Composite
Authors: Zhou Xiao Bing , Cheng Hui Feng , Wang Jun Ping , Lei Jin , Huang Tong Ming , Pan Wei Ming , Huang Qing
Published: November 2013

Precipitation hydrothermal method was used to synthesis carbon nanotubes (CNTs) /Ni0.5Zn0.45Co0.05Fe2O4 composites, and then 1wt%CNTs/Ni0.5Zn0.45Co0.05Fe2O4 ceramics were fabricated by spark plasma sintering (SPS) technique. The phase, microstructure and magnetic properties of 1wt%CNTs/Ni0.5Zn0.45Co0.05Fe2O4 were investigated. The results show that, the substitution of zinc ions by cobalt didn’t change the spinel phase of Ni-Zn ferrite. In the SPS process, CNTs promoted the sintering kinetics, and the liquid state of Ni can act as sintering aid to accelerate the grain boundary extension. After sintered by SPS at 750 °C for 5min, the density of the bulk is about 5.2g/cm3, the grain size increased to 91nm, and the saturation magnetization of the 1wt%CNTs/Ni0.5Zn0.45Co0.05Fe2O4 composite ceramics reached at 79.7emu/g.
Preparation, Structure and Properties of FeCrAl Honeycombs
Authors: Yu Jiao , Du Yu Jie , Zhou Yun
Published: November 2013

FeCrAl alloy powder is used to mix with an additive to prepare a powder mixed paste. FeCrAl alloy honeycombs are fabricated by extruding the powder mixed paste, then dried and sintered. While sintering at 1200°C, with sintering time increase, the volume of sintered honeycombs increase and density decrease. The structure parameters and properties of sintered honeycombs were obtained by measuring and calculating. Results show that wall thickness 0.18~0.23mm, cell number (1/in2) 316~339, clear cross section (%) 69~74, specific surface Sv (sq m/cu dm)2.35~2.52; specific heat capacity Cp(J/g.K) 0.60~0.70, heat conductivity κ (W/m.K) 6.52~6.78. SEM/XRD analysis shows that a large number of oxides formed on the surface of sintered honeycombs during sintering, such as Fe2Cr204, Fe2Si04, Al2O3.These oxides connect together to form film on surface of sintered honeycombs. By impregnating and baking test, the surface of sintered honeycomb can firmly adhere γ-Al2O3catalytic washcoat. The oxide film formed on the surface sintered honeycombs is benefit for adhering and supporting the catalytic active components.
Abrasion Properties and Thermal Stabilities of Poly(vinyl chloride)/Diatomite Composites
Authors: Zhan Feng , Chen Nan Chun , Zhang Xiao Hu , Huang Bin , Wu Zhi Neng , Zhu Qian
Published: November 2013

Mechanical properties, abrasion properties, thermal stabilities, and dynamic mechanical properties of poly (vinyl chloride) (PVC)/diatomite composites with different diatomite content prepared by melting blending were investigated. The results indicated that mechanical properties of composites have different performance due to diatomite participation, and the flexural modulus was improved. With an increase in diatomite, the abrasion resistance and thermal stability of composites were improved. Furthermore, the E' and Tg of composites could be enhanced effectively with diatomite participation. The optimum combined properties of PVC/diatomite composite were obtained with the adding of 40 phr diatomite.
Research on the Microstructure of Leather/Resin Composites
Authors: Zhang Hua Yong , Liu Xiao Jian
Published: November 2013

Reuse of leather wastes has been paid much attention. In this article, the chrome tanned cattle (pig) leather and unsaturated polyester resin or epoxy resin were used as raw materials, leather/resin composite material was prepared. The composite sections were examined by optical microscope and environmental scanning electron microscope. By observing the cross section morphology, the performance of composites can be speculated, the effective direction for further research on leather/resin composites and development can be provided.
Ferroelectric Properties and Microstructures of Bi4-x LuxTi3O12 Thin Films
Authors: Chen Min , Mei X.A. , Liu J.
Published: November 2013

Lu2O3-doped bismuth titanate (Bi4-xLuxTi3O12: BLT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. Lu-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675 °C to lower temperature and a improvement in dielectric property. The experimental results indicated that Lu doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BLT film with x=0.75 were 28 μC/cm2 and 65 kV/cm, respectively.
Preparation and Characterization of Novel Acrylate Emulsiones with Ketone-Hydrazide Crosslinking Structure Based on Application of Reactive Emulsifier
Authors: Wu Zhen , Zhong Chong Zhe , Song Yu , Zhang Ying Qiang
Published: November 2013

Polyacrylate emulsions (PAs) with core-shell structure were prepared by semi-continuous emulsion polymerization with diacetone acrylamide (DAAM) and adipic dihydrazide (ADH) as crosslinkable monomers and compound emulsifier system of SDS/0P-21/MS-1, reactive emulsifier NRS-10 as emulsifier respectively. The polyacrylate emulsion with keto-hydrazide crosslinking was characterized by Fourier transform infrared spectroscopy (FTIR), FTIR analyses demonstrated that the keto-hydrazide crosslinking reaction occur in the emulsion. The properties of both emulsions and films were tested by size analysis, viscosity analysis and others. The results showed that the average particle size with reactive emulsifier system of around 93 nm, coagulation rate of around 0.81% and water absorption rate of around 6.7% and the quality of polyacrylate emulsion with reactive emulsifier system was excellent.
Structural and Electrical Transport Properties of the Type-I Clathrate Phase Ba8Ga16InxGe30-x
Authors: Li De Cong , Wang Hai Rong
Published: November 2013

Thermoelectric (TE) devices are increasingly being seen as having the potential to make important contributions to reducing greenhouse gas emissions and providing cleaner forms of energy. A number of articles have been devoted to the thermoelectric properties of materials. From the search for novel and effective thermoelectric materials the clathrate structures has emerged as one of the most promising candidates for achieving very high thermoelectric figure of merit: ZT= α2σT/κ, where α, T, σ and κ are the Seebeck coefficient, absolute temperature, electrical conductivity, and total thermal conductivity, respectively [1]. For the past decade, caged clathrate compounds of group IV elements have attracted much attention because they would possess a low kL value as the theoretical minimum one, which results from rattling of atoms filled in their cages [2-3]. There are the type-I, type-III, and type-VIII structures in thermoelectric clathrates, but most compounds adopt type-I structure (space group No.223; Pm-3n). A large number of the type-I clathrates with the chemical formula of II8III16IV30 (II=Ba, Sr, Eu, III=Al, Ga, In, and IV= Si, Ge, Sn) have been synthesized and studied intensively [5-11], which results in relatively high ZT values such as 0.7 at 700 K for Ba8Ga16Ge30 and 0.87 at 870 K for Ba8Ga16Si30 [3]. Among type-I clathrates, a single-crystal n-type Ba8Ga16Ge30 grown using the Czochralski method with a ZT of 1.35 at 900 K is one of the most promising results [12].
Preparation and Ferroelectric Properties of Bi4-xTmxTi3O12 Thin Films
Authors: Li Bei , Yuan X.H. , Chen M. , Mei X.A.
Published: November 2013

Tm2O3-doped bismuth titanate (Bi4-xTmxTi3O12, BTT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. The experimental results indicated that Tm doping into BIT results in remarkable improvement in ferroelectric properties. The Pr and the Ec values of the BTT film with x=0.75 were 28 μC/cm2 and 80 kV/cm, respectively.
Preparation Technology of ITO Composite Oxides Nanopowder
Authors: Yan Ji Kang , Tang Wan Xia , Ni Er Xin , Gan Guo You , Yang Gang , Shi Zhe , Du Jing Hong , Zhang Jia Min , Liu Yi Chun , Yi Jia Hong
Published: November 2013

The technological parameters on synthesis rate of ITO nanometer by chemical coprecipitation were investigated. The effects of process parameters on synthesis rate of ITO nanometer powders were discussed by the range analysis of orthogonal experiment design. The dispersion features of ITO nanometer powder by ultrasonic dispersion or without were compared. The results show that the biggest factor that affects the powder synthesis rate is the pH at the titration end-point. Powder synthesis rate increases with the increase of pH value. When pH is 9, the powder synthesis rates are all above 90%. TEM images show that ITO nanometer powders are well dispersed without obviously agglomeration when anhydrous ethanol is used as dispersant. Particles have diversity of shapes, and the particle sizes distribute widely. After Ultrasonic physical dispersion, ITO nanopowders are well dispersed with no obviously agglomeration, narrow particle sizes of 20-30 nm and the approximation spherical particle morphology.
First-Principles Study of the ZnO(1120) Structure and Ti Adsorption
Authors: Liang Zhong , Gan Guo You , Yi Jian Hong , Yan Ji Kang , Du Jing Hong , Zhang Jia Min , Liu Yi Chun
Published: November 2013

Based on the density functional theory, this paper calculated the geometrical and electronic structural properties of ZnO(11¯20) surfaces and analyzed ZnO(11¯20) surfaces in the structural relaxation, electron density difference, densities of states and the Ti adsorption by using the first-principles and pseudopotential method. According to the computing result, ZnO(11¯20) surfaces are similar in geometrical structure and bulk; at the same time, when Ti adsorbs ZnO(11¯20) surfaces, the negative charge density is special high in the central region between Ti and O, and Ti-O shows obviously better performance than Zn-O in covalent bond, for the reason that the number of outer electron transferred from Ti to O is extremely limited, and the area of negative charge of the surface is large, which can lead to metallic characteristics on the surface
Determination of Constitutive Equation at the Deformation of Materials Using the Compression Test
Authors: Iordache Monica , Niţu Eduard , Iacomi Doina
Published: November 2013

Numerical Simulationis a Modern Method to Optimize Cold Plastic Deformation Processes in Order Toprovide Product Quality, Reduction of Time and Costs of Execution. One of Theimportant Problems of Numerical Simulation is the Mode of Characterizing Theplastic Behaviour of the Material which Undergoes Deformation. the Resultsobtained through Simulation are Closer to Real Ones as the Description Ofmaterial Behaviour of the Piece is Done as Accurately as Possible. Thesimulation Results Depend on the Stress-Strain Relationship which is Obtainedexperimentally by Compression Tests. the Paper Presents the Mode of Determiningthe Constitutive Equation Starting from the Results of the Compression Test.This Test was Used because it Allows Achieving High Strain and the Stressdistribution is Similar to other Corresponding Plastic Deformation Processes.
Estimation of Reliability Characteristics in a Production Scheduling Model with Failures and Time-Changing Parameters Described by Gamma and Exponential Distributions
Authors: Kempa Wojciech M. , Paprocka Iwona , Kalinowski Krzysztof , Grabowik Cezary
Published: November 2013

In the paper a classical model of failures is considered in that successive failure-free times are supposed to have Gamma distributions and are followed by exponentially distributed times of repairs. It is assumed that parameters of these distributions, in general, change with time. Basing on information about the number of failures and failure-free times in a number of periods of the same duration in the past, three different methods of estimation unknown parameters of the model are proposed. Next, predictions of the most important reliability characteristics are found.
Influence of Cutting Parameters on the Surface Quality of Round Parts Made from AZ61 Magnesium Alloy and Machined by Turning
Authors: Mustea Gheorghe , Brabie Gheorghe
Published: November 2013

The use of magnesium alloys in construction of different components of the mechanical systems (such: cars, aerospace vehicles, medical equipment etc.) is very efficient not only because it leads to reduction of the systems weight but also because it leads to reduction or elimination of the environment polluting and to reduction of the energy consumption. Generally, the main factors that influence the quality of the machined surfaces are as follows: cutting parameters, material properties, geometry of the tools, cooling liquids and lubricants, physical and mechanical properties of the subsurface layers etc. Among the above mentioned factors, cutting parameters are the factors that strongly influence the quality of the machined surfaces. The present paper analysis the results of the experimental investigation performed to determine the influence of cutting parameters (cutting speed, feed rate and cutting depth) on the surface quality machined by turning the AZ61 magnesium alloy. The main characteristics of the machined surface quality analyzed in experimental investigation were the surface roughness and hardness. The main conclusions resulted from the results analysis were as follows: the decrease of the feed rate led to surface roughness decrease and hardness increase; the increase of the cutting speed also led to an improved surface quality.
The Influence of the Feed Rate on the Quality of Surfaces Processed by AWJ at High Pressures
Authors: Schnakovszky Carol , Herghelegiu Eugen , Radu Crina , Cristea Ion
Published: November 2013

Abrasive water jet processing is one of the newest unconventional technologies. It can be used to cut different metallic materials (steel, titanium alloys, aluminium alloys, brass) or non-metallic materials (wood, plastics, glass, stone, granite etc.). Therefore, this technology can be successfully applied in different industries as: food industry, wood industry, aeronautic industry, automobile industry, mining industry. Between the advantageous of abrasive water jet processing technology it is worth noticing the following: it is rapid, very small processing forces are generated, it is silent, no thermal distortions occur.
The aim of the current paper was to determine the influence of the feed rate on the quality of surfaces processed by AWJ at high pressure. The parameters that quantified the quality of the processed surface were those defined in the ISO/WD/TC 44 N 1770 standard: width of the processed surface at the jet inlet (Li), width of the processed surface at the jet outlet (Lo), deviation from perpendicularity (u), inclination angle (α) and roughness (Ra).
The Metal Sheets Processed by AWJ. Analysis of the Surface Quality
Authors: Schnakovszky Carol , Herghelegiu Eugen , Tampu Nicolae Catalin
Published: November 2013

Abrasive water jet (AWJ) is a nonconventional machining process in which abrasive grains in a high-speed water jet collide with the sample and erode it. This technology has been developed as an alternative to the conventional processes in order to facilitate the processing of hard materials as stainless steel, titanium alloys, composite materials, etc. However, it is not limited only to hard materials, since it has been successfully applied to process softer materials as aluminum, copper, plastics. Also, the abrasive water jet technology can be used both, to process thin metal sheets and plates since it offers many advantages such as: good surface quality, no thermal distortions, minimal burrs, low machining force, high flexibility.
The aim of the current paper was to study the surfaces quality of samples made by aluminium, A1050, processed by AWJ in case of using different working regimes. The experimental tests have been performed on the Hydro-jet Eco 0615 water jet cutting machine. The parameters that have been varied were pressure, feed rate, abrasive quantity, distance between the cutting head and working sample while the diameter of focusing tube and diameter of water nozzle have been kept constant. The parameters taken into account to quantify the quality of the processed surface were those defined in the ISO/WD/TC 44 N 1770 standard (fig. 1): width of the processed surface at the jet inlet (Li), width of the processed surface at the jet outlet (Lo), deviation from perpendicularity (u), inclination angle (α) and roughness (Ra).
Researches for the Optimization of the Dehydration Process for Plums and Apricots
Authors: Tenu Ioan , Rosca Radu , Cârlescu Petru , Veleşcu Ionuţ Dumitru
Published: November 2013

The dehydration of the products of vegetable origin is a complex technological process, involving heat and mass transfer, which is largely affected by the nature and characteristics of the fruits, but also by the technical performances of the equipment. Experimental laboratory tests must be performed in order to evaluate the effect and importance of these parameters, using equipments which are able to reproduce the technological dehydration process. In order to achieve these goals a specialized test rig was designed and built. The laboratory test rig allows different dehydration experiments to be carried out; all the parameters that affect the dehydration process - temperature, speed and humidity of the drying agent before and after the mass and heat transfer takes place, the weight and temperature of the dehydrated product, the direction of the drying agent etc. - are continuously monitored. The continuous monitoring of the working parameters is performed by the means of a specialized industrial computer, which allows the data aquision and transfer to a PC. The paper presents the details regarding the design and working process of the laboratory test rig, as well as the experimental results concerning the dehydration of plums and apricots. The results show that the dehydration process is affected by the temperature and speed of the drying agent, by the size of the particles and by the thickness of product layer.
Modular Tooling System for Ultrasonic Assisted Cutting
Authors: Turc Cristian Gheorghe , Belgiu George , Cărăușu Constantin
Published: November 2013

The paper presents an approach on the possibilities of using of standard tooling systems mostly designed for the applications in the field of cutting processes to the ultrasonic assisted cutting processes, which is an extension of the conventional cutting processes for the purpose of surface roughness improvement and cutting forces reducing. A brief description of the device for the ultrasonic assisting cutting processes is presented, than an overview of the process integration technique, as well as some consideration regarding specific design requirements. A few solutions for rapid adaptation of ultrasonic assisting devices on conventional machining centers are presented, with different levels of flexibility and precision. Finally some recommendations were made, based on specific advantages and drawbacks of each tooling system. The presentation suggests the possibility to realize more standardized devices for ultrasonic assisted cutting processes based on commercial tooling solutions.
Profiling Method of Side Mill for Threading Screw for Dental Implants
Authors: Berbinschi Silviu , Baroiu Nicuşor , Teodor Virgil , Oancea Nicolae
Published: November 2013

In this paper, it is analyzed, in a comparative way, two methods for profiling disc tools (mills or grinding wheels) for generation of specific threads used in the construction of the prosthetic screw for dental implants. It is proposed an analytical method, based on the fundamental theorem of the surfaces enveloping versus a graphical method, developed in CATIA. They are presented numerical examples for the both methods.
Investigation Techniques of In Situ AlMg/AlN Metal Matrix Composites via Reactive Gas Injection
Authors: Florea Raluca Maria , Bălţătescu Oana , Buzăianu Aurelian , Carcea Ioan
Published: November 2013

In this paper characteristics of an AlMg/AlN composite produced in-situ and processed in a flowing N2 atmosphere is investigated. Some critical parameters such as the manufacturing process temperature, the percentage of the magnesium consumed, the flowing reactive gas flow and the time for completing the manufacturing are considered as variables for the parametric investigation. Moreover, the effect of different amount of Mg employed has been also investigated, since Mg acts as a catalyst at the surface both for the gas/liquid and solid/liquid systems.
Traditional methods were used for the basic characterization of the composite. The microstructure of the composite was investigated by optical and scanning electron microscopy (OM, SEM). SEM analysis was performed in order to observe the microstructural evolution as a function of the Mg content and to identify some reasons of the presence of porosity or any irregularities within the metal matrix. The evolution of mechanical properties, in terms of microhardness, at different percentage of Mg were monitored. By EDS technique the distribution of the elements was obtained.
Furthermore, employing an optimization process, uniform dispersion of the strengthening (AlN) particles in the metal matrix with homogeneous properties along the composite material is obtained. Based on the aforementioned statements, it can be concluded that the reactions between Al, Mg and the N2 atmosphere induce spontaneous infiltration in the metal matrix.
The complete mix of properties and experimentally assessed parameters can be used for industrial purpose manufacturing design and development.
The Stress Distribution of a Layered Contact Cam Mechanism Using Finite Element
Authors: Băsescu Gică Narcis , Crîșmaru Ionuț Vasile , Strugaru Sorin Iacob , Paulin Constantin , Bârcă Eduard Sebastian , Munteanu Corneliu
Published: November 2013

This paper analyses the stress distribution of deposited cams by means of finite element method. The modelling of the internal tension state was made as a comparison between two types of cam mechanism configurations: a cam and plane cam follower with metallic coating deposited on the contact surface and cam with metallic coating and plane cam follower. The model used in the simulation was made in Solidworks. The model includes the geometry of the cam and cam follower and their assembly with coatings and the definition of the materials properties. The material properties used are those of 18MnCr11 for the base material and 40Cr130 for the coating. The defined geometric model was imported to the Static Structural module from Ansys 13.
Simulation and Performance Analysis of a FMS/CIM Using Stochastic Timed Petri Nets
Authors: Coman Daniela , Ionescu Adela
Published: November 2013

This paper focuses on the modelling, simulation and the performance analysis of a flexible manufacturing system using stochastic timed Petri nets so as to evaluate various performance parameters such as utilization rate of machines, deadlock detection, cycle time, and throughput rate of system in order to obtain the optimum productivity. The simulation of the manufacturing system using Petri nets provides the possibility to view the manufacturing process in time. Petri net model is implemented in Petri Net Toolbox under MATLAB environment. It is achieved the graphic construction of the net. Then, transporting it into a specific mathematical formalism it is made, so that the fulfiled structure to be fully retrieved and used to bring out the internal dynamics of the model. It is validated in this way the net topology, the evolution of (their dynamics), as well as the structural and behavioral properties (corresponding to checking if resources usage is stable and the model have no deadlocks). Some global performance indicators are determined in order to evaluate the performance of the proposed manufacturing system.
Real-Time Monitoring Station for Production Systems
Authors: Ćwikła Grzegorz
Published: November 2013

Real-time monitoring of the flow of materials, semi-completed and completed products during production process is necessary practice for every company because of need for optimal production management. Identification of technological operations, parts, products and persons responsible for any production stage is possible using means of processes control devices and automatic identification systems. Paper describes the in-line monitoring station designed for tests of real-time production monitoring methods. Available sources of information are RFiD, bar codes, and vision system. These data sources are integrated into the in-line production monitoring station. Modular production system model or small production system can be placed under the In-line station as an object of monitoring. Advanced PLC integrates control over subsystems and allows communication between hardware and software components of data acquisition system. Data acquired from the in-line research station is stored in a dedicated database, then processed and analysed using MES (Manufacturing Execution System) software.
The Inverse Problem of Kinematics as the Tool for Determination of Motion Trajectories Exercised by Worm Drives of a Stewart Platform
Authors: Dymarek Andrzej , Dzitkowski Tomasz
Published: November 2013

The paper presents how to find out motion trajectories for individual platforms incorporated into a Stewart platform. The differential equations for motion of actuators are resolved under the assumed initial preconditions. Also are presented graphs for motions of end tips of actuators incorporated into the platform structure. The study makes up one of indispensable stages within the engineering process aimed to design a vehicle simulator for disabled people to help them learning how to drive a car.
Synthesis of Constructive-Functional Parameters to Improving the Dynamic Behavior of Automatic Mechanisms
Authors: Stelian Ghenadi Adrian , Topliceanu Liliana , Bibire Luminita
Published: November 2013

Producing of mechanisms for automatic tool (ATCM), for machining centers requires higher performance, in terms of: the reduction of effective time for tool, simplification of kinematic chain, the increasing of reliability and operational safety, the reduction of weight of the entire subassembly, the increasing of positioning accuracy in handling tools. The paper presents how these desiderate can be achieved by improving the dynamic behavior. The objectives of the paper focused on the development of a methodology which allows judicious choice of functional-constructive parameter values, still from the design phase in order to achieve an optimization of the dynamic behavior of mechanisms for automatic tool change. The inclusion of dynamic model for the actuation (hydraulic) in full dynamic model has the advantage that it takes into account real parameters which are involved in the operation of these mechanisms. This paper develops a methodology that allows judicious choice of functional-constructive parameter values, still from the design stage. To obtain a version that is the closest to optimal functioning, in terms of dynamic analysis of the mechanism, the authors propose to develop a method of multi-criteria evaluation on dynamic characteristic parameters. This method ensures the choosing the closest to optimal functioning, in terms of dynamic analysis of mechanism.
UML Models of Design and Knowledge Representation for Technical Production Preparation Needs
Authors: Grabowik Cezary , Kalinowski Krzysztof , Paprocka Iwona , Kempa Wojciech M.
Published: November 2013

Having in mind the need of the computer adding of the technical production preparation functions the elaboration of models of the design and knowledge representation is essential. In order to prepare these models the object paradigm in the meaning of object oriented techniques and the UML language would be applied. Thanks to this solution the coherent representation of the design and manufacturing knowledge in the framework of a new created CAPP is possible to achieve. The main purpose of the presented work is to show and discuss original models of a design and manufacturing knowledge representations. In the proposed solution the product design is represented by means of the hierarchical class structure in which a particular class is responsible for representing a characteristic type of the model feature. The manufacturing knowledge similarly to knowledge representation is also represented by means of the hierarchical class structure. Each class in the manufacturing knowledge model stores a certain amount of manufacturing knowledge. This model allow representing both procedural and declarative knowledge. The declarative character of the model results from storing of manufacturing process planning rules whilst procedural one from recording of manufacturing instrumentation, cutting parameters etc. selection procedures. Having these models done it is possible to undertake a research on connections between a design and manufacturing knowledge representations.
The Self-Excitation Phenomenon of Quasi Shielded Inductive Proximity Switches
Authors: Michalski Piotr , Hetmańczyk Mariusz Piotr
Published: November 2013

Authors of this article had to build the Poka-Yoke [ unit for unusual geometry element, which require to use the inductive proximity switches with relatively small diameter and good sensing range. Industrial sensors suppliers putted on to the market new type of sensor named quasi flush or semi flush which fulfill the needs. An article shows the observed influence of the geometry of tested elements for the self-excitation phenomenon of quasi shielded inductive proximity switches. In consequence this phenomenon can cause in false quality control and passing the wrong elements through the Poka-Yoke unit.
Process Smoothing of the Inner Surface of Cylinders after Honing and its Role in Eliminating Wear in the Activation of the Heat Engine
Authors: Chirita Daniel
Published: November 2013

It is known that one of the basic requirements of the market economy is product competitiveness; competitiveness ensures their operating performance and the costs of obtaining them and therefore manufacturing costs. Process smoothing of the cylindrical internal surfaces must ensure a very high diameters precision and a low surface roughness. Cylindrical inner surface smoothing can be achieved through the following processes: indoor spinning roller, honing, lapping, etc. Fine machining processes without material removing, ensures based on the initial surface quality, initial quality metal cutting, work regime that is processed, hardness increasing by (20…60)%, roughness Ra=(1.6…0.4)μm, and fine processing procedures with material removal, ensures a high quality of machined surfaces, resulting in roughness Ra=(0.4…0.02)μm. Deformed layer size reducing at the previous processing, and reducing of micro depths serving as lubricant deposits, contributes to increasing wear resistance of cylinder surface. Cylinder inner surface smoothing by honing machines is performed on honing machines with a specially designed tool called hon. In the honing process, abrasive grain trajectories are forming on the cylinder a network of fine spiral lines. If carried out on a flat surface, these helical lines become straight and intersecting an angle 2α. Processing accuracy depends on the accuracy of the previous bore.
In this paper, the focus is on several methods of heat engine cylinder forming the passage of the piston and rings share repair and their effect giving the engine operating parameters specified by eliminating the running operation. With the help of experimental and theoretical data and the methodology of approach to the subject, several aspects have been clarified regarding the depth of the asperities on the honed surface compared to a process-smoothed surface. The influence of all factors on the processing results has not been thoroughly explained. The following research methods shall be discussed in the future: improving the method of adjusting the pressure of the centrifugal rollers with the help of an automatically controlled device and the creation of an auxiliary device to adjust the bars to which the rollers are connected according to the internal diameter of the processed cylinders.
A Method to Obtain a Generalized Model of the Pressure Evolution within the Braking System of a Vehicle
Authors: Marinescu Marin , Vilau Radu , Truta Marian , Fieraru Octavian
Published: November 2013

Military vehicles have to travel, at least from time to time, on the national road network. Whenever that happens, the legal requirements have to be met with respect to the systems that contribute to the traffic safety. One of these systems is the braking system. On the other hand, most of the military vehicles arent that up-to-date that the rest of the traffic partners are. Therefore, a military automotive engineer should have at hand a fast method to diagnose the technical status of the braking system even the checked vehicle is rather old. It would be also even better if the faulty party were accurately identified. The paper aims at providing a method helps the diagnosing teams to quickly compare the behaviour of an actual vehicle braking system status with a general model that had been acquired by tests. Since nobody provided that kind of information during 70s, our model derived from a large number of tests that have been performed on good technical condition vehicles. Key words: vehicle braking system, parametric models, data-based models.
A Dynamic Model of the Human Body in the Vertical Direction
Authors: Picu Mihaela
Published: November 2013

This paper presents a dynamic model of a human spine subjected to vertical vibrations. The lack of information regarding the negative load of the spine obstructed the development of an adequate dynamic model. The spine can be considered the resilient load-bearing member, and the mass of the upper body can be considered to be resting on top of the column. The described situation refers to the case in which the acceleration is applied in such a manner that the body is pushed down into the seat. The natural frequency, the dumping coefficient and also the critical levels of the force from the spinal direction are calculated. Fig. 1 presents a biomechanical model of the human body under vertical vibration. In all cases analyzed was thesteptype excitation. It was considered that the response tosteptype excitation has greater practical importance than theweightresponse because a large class of real signals that are external dynamic disturbances of the human body can be treated easily with the help ofstep-type function (Heaviside functions) or combinations thereof. Fig. 2 presents the force response for differents excitation times: (a) τ1=0.01s; (b) τ1=0.10s; (c) τ1=1.00s. There is a transient increase of transient regime with increasing of model time constant value.Key words:biomechanical model, vertical vibrations, force response, transient regime.
Short Term Prediction of Hydroelastic Dynamic Response in Random Waves for an 1100 TEU Container Ship
Authors: Rubanenco Ionica , Domnisoru Leonard
Published: November 2013

This paper is focused on a short term statistical analysis of the ship dynamic response in random head waves. The waves and the ship responses are considered to be homogenous random processes, being described by a short term Rayleigh first order probability density function. The waves are described in the frequency domain by ITTC power density spectrum function, with time domain formulation by Airy-Faltinsen and Longuet-Higgins models. The numerical analysis are carried out with own program codes package DYN, based on the hydroelasticity theory, with oscillation and vibration components, taking into account the ship speed influence on the dynamic response. The dynamic analysis is based on frequency domain procedures, for linear steady state response, and direct time domain integration procedures, for non-linear and transitory response, resulting power and amplitude density spectrum functions by Fast Fourier Transformation method. The numerical analyses are applied for an optimized 1100 TEU container ship structure, considering six different ship speeds, from 0 to 20 knots, for the full containers loading case. The short term statistical numerical results are pointing out that the ship speed has higher influence on the global vibrations response in compare to the oscillations response, with better accuracy on the non-linear model.