bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Mechanical Manufacturing with Design and Analysis of an Intermittent Separation Bricks Machine
Authors: Shen Xiao Hua , Peng Qiu Ping , Li Leng Wan , Li Yu Ting , Chen Ding Fang
Published: March 2014

In order to better meet the needs of brick mechanized packaging,design full-automatic brick packaging line intermittent separate mechanism,cam with partial gear combined with exercise, can be a smooth and efficient completion of the process of lift brick. According to the actual functio
-nal requirements,calculate the size of the main components.Agencies coordinated through comput-ational analysis, operation with a fixed motivity driven, by changing the number of teeth of the partial gear to meet the separation requirements of the different thickness brick.By the dynamics simulation of the mechanism,to determine whether the mechanism meets the design requirements.
Applied-Information Technology in the Government Regional Information Sharing Operating Mechanism Based on Cloud Computation
Authors: Zhao Er Dan , Zhang Zhao Feng , Zhu Jie , Wu Shu Fang
Published: March 2014

Information technology has been widely used not only in econimic fileds but also the operation of government. The development of electronic government affairs has totally change the way of the government operation model. Cloud computation can offer safe and reliable data storage, and it can offer an efficient scheme for the electronic government affairs. We propose to use the clustering algorithm in cloud to efficiently and effectively deal with the data from all the government departments. After clustering the information, similar data are grouped together; each department can choose the interested information.
Effects of Processing Method and Nanofiller Size on Mechanical Properties of Biomedical Thermoplastic Polyurethane (TPU) Nanocomposites
Authors: Osman Azlin Fazlina , Edwards Grant , Martin Darren
Published: March 2014

The effects of processing method and nanofiller size on mechanical performance of biomedical thermoplastic polyurethane (TPU)-organosilicate nanocomposites were examined. High energy milled organofluoromica nanofillers having reduced platelet aspect ratio and tactoid size were produced in order to obtain an overall better dispersion and more efficient TPU-organofluoromica nanocomposite reinforcement. Regardless the processing method, the lower aspect ratio milled nanofillers resulted in improved quality of dispersion and delamination when incorporated into the TPU and hence induced greater mechanical properties as compared to the non-milled nanofiller. However, the high temperature applied in melt compounding process might induce some degree of degradation of the dual surfactants employed, producing free amines and alkenes that can subsequently reduce the molecular weight of the TPU. Therefore, the expected larger increases in mechanical properties of melt blended TPU nanocomposites were not observed.
Microstructure Study on Gd-Doped BaTiO3 Sol-Gel Multilayer Thin Films Using AFM for Optoelectronic Applications
Authors: Teh Yen Chin , Saif Ala’eddin A. , Jamal Z.A.Z. , Poopalan Prabakaran
Published: March 2014

Gadolinium doped barium titanate (Gd-BaTiO3) thin films with the molar ratio of 70:30 have been fabricated on SiO2/Si substrates using sol-gel technique. The effect of number of deposited layers on the grain size and surface morphology has been investigated using an atomic force microscope in contact mode. AFM micro-images show that the films have well distributed grains, dense and crack free surface. In general, the results show that the grain size increases from ~170 nm to ~189 nm as the number of deposited layers increase from one to four layers which attributed to the grain growth mechanism during heating and annealing processes. However, the surface of the films is analysed through amplitude parameters to find out that the films surface is smooth with a predominant for peaks and relatively low number of high peaks and low valleys.
Cocoa Pod Husk and Corn Stalk: Alternative Paper Fibres Study on Chemical Characterization and Morphological Structures
Authors: Daud Zawawi , Awang Halizah , Mohd Kassim Angzzas Sari , Mohd Hatta Mohd Zainuri , Mohd Aripin Ashuvila
Published: March 2014

Due to a shortage of wood source fibre in paper making industrys interest to agriculture residues fibre as a potential fibre sources in this industry. In this situation, importance has been developing in the paper industry from agriculture residue that will replace the wood fibre. Cocoa pod husk and Corn stalk are agriculture residues, which is good materials for paper production. The objectives of this study are to investigate the chemical characterization and surface morphology structure of these materials. The main components of materials which are cellulose, hemicellulose, lignin and ash content were parameters that involved in determination of chemical characterization in this study. The determination of chemical composition was accordance to Kurshner-Hoffner approach (cellulose), Chlorine Method (hemicellulose), T 222 om-06 (lignin) and T 211 om-07 (ash content). Scanning electron microscopy was used to observe the surface structure of materials. From results obtained, corn stalk shows the higher amount in cellulose (39%) and hemicellulose (42%) content compared to the cocoa pod husk. In addition, lower lignin content also obtained in Corn stalk (7.3%) rather than that Cocoa pod husk (14.7%). From Scanning electron microscopy images, Corn stalk and Cocoa pod husk contained abundance lignocellulosic and rough surface structure due to the untreated materials. The result either chemical characterization or surface morphology that obtained in Corn stalk and Cocoa pod husk fibre wastes can be used successfully as an alternative fibres sources in papermaking application.
Preparation and Characterization of Flexible Polyurethane Foams from Palm Oil-Based Polyol
Authors: Lumcharoen Duangphon , Saravari Onusa
Published: March 2014

Flexible polyurethane (PU) foams were prepared by replacing commercial petroleum-based polyether polyol with palm oil-based polyol up to 50 wt%. Palm oil was converted to polyol by transesterification reaction with glycerol using calcium oxide as a catalyst. PU foams were then prepared from reaction between mixtures of palm oil-based polyol and petrochemical polyols with toluene diisocyanate (TDI) using water as blowing agent. The morphology and physical-mechanical properties including apparent density, indentation hardness, compressive deflection coefficient or support factor, tensile strength, and tear strength of the prepared foams were characterized and compared to those of reference foam prepared using only conventional petrochemical polyols. Scanning electron microscopy (SEM) indicated that the cellular structures of all the prepared foams were semi-open and the cell size decreased with higher amount of palm oil-based polyol. The apparent densities and the compressive deflection coefficient of the PU foams increased with the increasing amount of palm oil-based polyol, while the indentation hardness showed the opposite tendency. Furthermore, the obtained foam modified with palm oil-based polyol of 20 wt% were found to have the highest tensile and tear strengths.
Deflection Behaviour of Irregular-Shaped Polyethylene Terephthalate Fibre Reinforced Concrete Beam
Authors: Irwan J.M. , Asyraf R.M. , Othman Norzila , Koh H.B. , Aeslina A.K. , Annas M.M.K. , Faisal S.K.
Published: March 2014

This paper reports the results on deflection behaviour of reinforced concrete (RC) beam conducted using irregular-shaped Polyethylene Terephthalate (IPET) as a fibre. Three volume fraction of IPET fibre is used namely, 0.5%, 1% and 1.5%. All RC beam specimens are tested under four point loading under flexural capacity behaviour. The results for deflection behaviour namely cracking stage, yield stage and ultimate stage and ductility are reported. The results than are compared with control RC beam. It is found that the addition of IPET fibre improves the first crack and ultimate strength as well as ductility of RC beams proportional to the increment of volume fraction of IPET fibre. Therefore, based on the results reported, the addition of IPET fibre significantly increases the deflection behaviour of RC beam.
Properties Comparisons and Cost Analysis of Asphaltic Cement Grade 80/100 and 60/70 Modified with Crumb Rubber and SBS Polymer
Authors: Phetcharat Sudniran
Published: March 2014

Enhancing the quality of AC 60/70 using crumb rubber and SBS polymer has its limitations. These limitations are in terms of lower than standard penetration properties, softening point and ductility based on the polymer modified asphalt cement TISI 2156-2547 standard. This research aimed at eliminating the problem by using AC 80/100 and modifying it with crumb rubber or SBS polymer at different quantities. Two types of AC were compared in this research. The qualities tested were penetration, softening point, ductility, flash point and weight loss due to heat. The results of the quality of properties tested were analyzed based on TISI 2156-2547 standardfor AC. Furthermore, the research goes on to analyze the cost effectiveness of the modification and found that modified AC 80/100 has better qualities than AC 60/70 but is 5% higher in cost. Modifying AC 80/100 with 5 wt.% crumb rubber and 4 wt.% SBS polymer will decrease the penetration and ductility problem compared to modifying AC 60/70 with the same additives. However, the softening point is still a problem for both grades of AC.
Fabrication and Characterization of Chinese Drug-Loaded Nanoporous Materials
Authors: Xu Lan , Si Na , Liu Hong Ying
Published: March 2014

Chinese drug-loaded nanoporous materials were prepared from electrospinning Poly (butylenes succinate) (PBS) solutions with an additive of Chinese drug and a mixed solvent of chloroform and iso-propylalcohol in a single processing step. Characterizations of the samples, such as morphology, wettability and permeability, were studied by means of scanning electron microscope, full automatic micro droplet wettability measurement instrument and fabric air permeability performance tester. The results showed these characterizations could be controlled by adjusting electrospinning parameters such as flow rate and drug concentration. And the electrospun nanoporous materials might offer the potential for direct fabrication of biologically based and high-surface-area porous materials.
Nanoindentation and AFM Studies on Tungsten Carbide Crystals in WC-Co Hardmetal
Authors: Csanádi Tamás , Bľanda Marek , Duszová Annamária , Hvizdoš Pavol , Dusza Ján
Published: March 2014

The room temperature elastic and plastic properties of the WC grains of WC-9%Co hardmetal were investigated by nanoindentation and atomic force microscope (AFM). Two easily distinguishable crystallographic planes (using EBSD analyses) were investigated, namely the basal and prismatic planes, on which nanoindentation tests were performed with different applied loads from 1 mN to 50 mN to determine the hardness and reduced-modulus, respectively. The results deriving from nanoindentation show significantly higher indentation hardness on basal planes (HIT=28.9±0.1 GPa) than on prismatic ones (HIT=21.9±0.1 GPa) over 10 mN load. For loads below that the results were inconsistent. The corresponding indents were checked by AFM and correct values of hardness were found. The discrepancies indicate the inaccuracy of the built-in evaluation procedure (Oliver-Pharr method) in this low load, or more precisely in the low indentation depth range. It is pointed out that below 50 nm contact depth the applied built-in contact area-contact depth function is not appropriate and a new correct contact area-contact depth function is proposed, thus the resulting recalculated hardness values are in good agreement with the AFM measurements.
Identification of Stress-Strain Relation of Aluminium Foam Cell Wall by Spherical Nanoindentation
Authors: Králík Vlastimil , Němeček Jiří , Koudelka Petr
Published: March 2014

The aim of this paper is to identify, in addition to elastic properties, inelastic properties of tiny aluminium foam cell walls that can be directly deduced from the loaddepth curves of spherical indentation tests using formulations of the representative strain and stress. Constitutive parameters related to plastic material with linear isotropic hardening, the yield point (122 ± 17 MPa) and tangent modulus (950 ± 377 MPa), were obtained in this work. Spherical indentation and uniaxial tension experiments have also been performed on a standard aluminium alloy EN AW 6060 to explore the accuracy of the analytical models used to predict the uniaxial stressstrain in wide strain ranges. Some deviations received from different tests arose and, therefore, their effect on the evaluation of inelastic properties was discussed.
Wear of Human Enamel and Dentin
Authors: Čtvrtlík Radim , Tomaštík Jan
Published: March 2014

The wear of human tooth enamel and dentin has been studied and compared using a repetitive constant load scratch test. Depth sensing indentation with spherical tip was used for measurement of hardness and reduced modulus. An analysis of residual wear tracks was performed with scanning laser confocal microscopy. A procedure for evaluation of repetitive scratch test was proposed. Results showed that the microtribological behavior of enamel differs obviously from that of dentin.
Nanoindentation of Human Tooth Dentin
Authors: Jíra Aleš , Němeček Jiří
Published: March 2014

Biological tissues belong to the group of materials highly dependent on its micro structure. A variety of results may be found in the study of human teeth whose local composition and mechanical characteristics show considerable variations. The article deals with the measurement of elastic micromechanical characteristics in the root part of human tooth dentin. An extracted tooth was analyzed in two typical directions, i.e. longitudinal (from the tooth crown-neck to the root) and transverse (in the middle of the root part). Values of the modulus of elasticity in walls of the tooth root in the longitudinal and transverse directions were identified by means of nanoindentation. The development of the modulus of elasticity was measured in several parallel rows proceeding from the outer edge of the tooth root towards the root canal. The values measured in the dentin part of the tooth root ranged around ~17 GPa (cement-dentin boundary), ~23 GPa (middle part of dentin) and ~14 GPa (dentin-root part interface). In the longitudinal section, the value of the modulus of elasticity was almost constant in the majority of tested volume (~18 GPa) with some deviations in peripheral part (end of the root) due to changes in microstructural orientation from sagittal plane. The differences revealed a low degree of anisotropy of dentin.
Modeling of Stress Distribution in Dental Implant in Frontal Part of Mandible
Authors: Németh Dušan , Kučera Ján , Lofaj František , Ivančo Vladimír
Published: March 2014

The aim of this work is the modeling of the stress distribution in cortical and trabecular bone of model frontal part of mandible by FEM analysis using linear static methods applying monocortical and bicortical fixation of dental implant. Depending on the position of the screw thread with regard to the bone surface, three different cases were simulated: exactly on the bone surface, 1,5 mm above and 0,5 mm below the surface of the cortical bone. It was found out that the stress field in the cortical part and the implant are considerably lower in the case of slightly recessed position in contrast with the above and normal position of the implant in both, monocortical and bicortical fixations. However, bicortical fixation in this case generates slightly lower stress field in the bone and implant parts than in monocortical fixation. Monocortical fixation is otherwise slightly more favorable from the viewpoint of maximum stresses in the bone in the case of exact and above positions of the implant.
Micro-CT Based Imaging and Numerical Analysis of Bone Healing
Authors: Řehák Kamil , Skallerud Bjørn
Published: March 2014

During distraction osteogenesis (bone lengthening) one phase is lengthening and a second phase is consolidation (fixed length, bone maturation). In this second phase of fracture healing, the callus consists of several tissue types. The response of callus bone to mechanical loading can determine the progress of treatment. The mechanical strain distribution could provide additional information of fracture healing in the same way as for bone remodeling. The architecture and tissue properties significantly affect the strength of the whole callus bone. This article focuses on imaging and numerical analysis of bone fracture healing based on input information obtained from micro-CT scans. The objective of this study is to focus on how different stiffness threshold values affect the load carrying tissue architecture and how this further influences the strain distributions within the callus. Finite element simulations are employed to investigate this. A rabbit tibia fracture callus was micro-CT scanned 30 days after osteotomy using an isotropic voxel size of 20 μm. Four computational models were created with different pixel threshold values to cover a wide range of callus tissue properties, with the purpose of finding an optimal threshold value. Optimal means here a finite element model which is computationally feasible and still contains the main load carrying tissue.The values of bone volume/total callus volume (BV/TV), bone area/total callus area (BA/TA), trabecular thickness, structure model index (SMI) were quantified to compare the differences between models. All finite element models were axially loaded to investigate the influence of threshold value on the callus reaction and influence of including the soft tissue. The BV/TV and BA/TA values indicate that for a certain threshold level, finite element models are suitable. However, a too high threshold leads to invalid finite element models. The finite element method (FEM) could be useful tool in understanding of fracture healing process.
Corrosion Behavior of Human Teeth Measured by Nanoindentation Method
Authors: Kašiarová Monika , Galusková Dagmar , Vilčeková Zuzana , Tatarko Peter , Gaalová Petra , Galusek Dušan
Published: March 2014

The decrease of the mechanical properties – hardness and reduced elastic modulus after corrosion in white wine was measured. Under static corrosion conditions no significant decrease was observed up to 8 hours of corrosion. Dynamic corrosion conditions cause detrimental decrease of properties (one order of magnitude) compare to the results of static corrosion test. This is due to the removal of the harder outer layer of the enamel during polishing. To obtain a relevant data concerning corrosion test, natural surface of a tooth should be investigated and tested.
Residual Stresses and Young's Moduli of Plasma Sprayed W+Cu Composites and FGMs Determined by In Situ Curvature Method
Authors: Matějíček Jiří , Mušálek Radek , Chráska Pavel
Published: March 2014

In this work, application of the in-situ curvature method on plasma sprayed composite and graded coatings is presented. First, uniform composites of different W/Cu ratio, were sprayed by water stabilized plasma. By continuous monitoring of the curvature of a flat specimen during spraying, the stress evolution throughout the entire history of coating formation was traced. By a simultaneous monitoring of curvature and temperature during post-deposition cooling, Youngs moduli of the coatings were determined. Second, a 5-layer stepwise functionally graded material (FGM) was sprayed. With the knowledge of each layers properties, the complex evolution of deposition, thermal and residual stresses in the FGM could be determined. The ability to determine the stresses and mechanical properties with a spatial resolution comparable to the thickness of one spray pass is demonstrated.
Thermomechanical Properties of CoNiCrAlY-BN-Polyester Composite Coatings Elaborated by Atmospheric Plasma Spraying
Authors: Aussavy Delphine , Bolot Rodolphe , Peyraut François , Montavon Ghislain , Selezneff Serge
Published: March 2014

This study concerns the mechanical properties of CoNiCrAlY-BN-Polyester composite coatings elaborated by Atmospheric Plasma Spray (APS) and used as abradable seals in the aeronautic industry. The objective is to determine the influence of the diameter of the plasma torch on the coating micrograph morphologies and on the resulting coating thermal and mechanical effective properties. The thermo-mechanical effective properties were then estimated by Finite Element modelling (thanks to the multipurpose finite element software ANSYS) based on coating microstructures captured by Scanning Electron Microscopy (SEM) and Optical Microscopy (OM)
Mechanical Properties of HVOF Sprayed, Flame and Laser Remelted NiCrBSi Coatings
Authors: Houdková Šárka , Smazalová Eva , Bláhová Olga , Vostřák Marek
Published: March 2014

The influence of thermal post-treatment by means of flame and laser energy on the mechanical properties of NiCrBSi coating was studied. The evaluation was done in terms of microstructure, surface hardness, microhardness and instrumented indentation. The microstructure evaluation showed an increase of coatings inner cohesion, together with the creation of metallurgical bond between the coating and the substrate material. In the the case of laser remelted coating, the creation of thick transition layer responsible for lower measured microhardness and hardness value was proved.
Influence of the Microstructure on Macro/Micro versus Nanohardness of SiC Ceramics
Authors: Kovalčíková Alexandra , Dusza Ján , Šajgalík Pavol
Published: March 2014

The influence of microstructural variations on the macro/microhardness, nanohardness and Young`s modulus of liquid phase sintered silicon carbide (LPS SiC) has been observed. In order to modify the microstructures some samples were further heat treated at 1850°C for 5 hours to promote grain growth. The depth-sensing indentation tests of SiC materials were performed at several peak loads in the range 10-400 mN. For a better assessment, the indentation values of hardness and Young`s modulus modulus of SiC matrix were also compared to the hardness and Elastic modulus of individual SiC grains. The comparison of macro/micro and nanohardness showed that nanohardness was significantly higher, generally by 6-7 GPa. The nanohardness of individual plate-like SiC grains was around 2 GPa higher than nanohardness of SiC matrix.
Mechanical Properties of Nanotextiles Determined with Digital Image Correlation
Authors: Němeček Jiří , Jandejsek Ivan
Published: March 2014

The paper is devoted to the assessment of mechanical properties of nanotextiles prepared from polyvinylalcohol by electrospinning. The nanotextile is composed of a multi-layered net of cross-linked fibers with individual diameters of approx. 200-500 nm. Strips of the textiles were tested in a standard electromechanical testing device by uniaxial tension. Precise local strain measurement was provided by the digital image correlation method. The overall nanotextile Young's modulus was found to be 277±9 MPa (for strains <1%) and exhibited small variations as well as ultimate strength (10.3±0.9 MPa at ~13% strain). The deformation mechanism includes alignment and stretching of the fibers in longitudinal (load) direction (initial linear part), yielding with transversal textile smoothing and textile rupture (at strains ~13%). The progress of apparent Poisson's ratio (5.5-0.52) was also monitored with the digital image correlation.
Spark Plasma Sintering of Multilayer Ceramics – Case Study of Al2O3-Mg(Ca)TiO3 Sandwich
Authors: Ctibor Pavel , Kubatík Tomáš , Chráska Pavel
Published: March 2014

Spark plasma sintering enables very rapid fabrication of bulk ceramic materials. Suitability of this technique for preparing of multilayer ceramic discs is up to now relatively seldom reported. Our work is focused on a bi-layered disc consisting of thick Al2O3 layer and comparably thick Mg (Ca)TiO3 (MCT) layer sintered in one run. Al2O3 powder was nanometric (less than 40 nm) and composed of the hexagonal α-phase whereas MCT is a solid solution of two orthorombic perovskites. Pre-sintered and crushed MCT powder was coarser than alumina, up to 125 μm. The purpose of this material combination was creating of dielectric sandwich consisting of capacitor MCT material and resistor nanoalumina material. Spark plasma sintering run was done at 1200 °C, using pressure 80 MPa and dwell time only 2 min. Resulting sandwich was subjected to microstructural observations and cross sectional measurement of microhardness. On the border between Al2O3 and MCT the microhardness was higher than in MCT but has markedly higher dispersion than in the individual components. The MCT material exhibits birefringence in the polarized light [1]. We attempted to correlate the microhardness of individual MCT grains to their orientation indicated by birefringence.
Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia
Authors: Náhlík Luboš , Máša Bohuslav , Hutař Pavel
Published: March 2014

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.
Determination of Local Mechanical Properties of Si3N4 Based Foams
Authors: Vilčeková Zuzana , Kašiarová Monika , Domanická Magdaléna , Hnatko Miroslav , Šajgalík Pavol
Published: March 2014

Local mechanical properties, particularly the hardness and Youngs modulus of highly porous silicon nitride based foams were studied in this work. Silicon nitride foams were prepared using polyurethane foam replication method to obtain appropriate cellular structure suitable for bio-application. Two types of the polyurethane foams were used (with average pore size 0.48 mm and 0.62 mm). Some of these samples were prepared by single or multiple infiltrations. The effects of structures, temperature of calcination, volume fraction of Si3N4 powder and number of the infiltrations on the local mechanical properties were investigated. The Youngs modulus of studied samples range from 12 to 46 GPa at the macroscopic scale measured by resonant frequency technique and from 10 to 28 GPa at the microscopic scale measured by instrumented indentation. Results showed increase of the hardness and Youngs modulus with increasing of the calcination temperature, with increasing of the number of infiltrations and also with increasing of volume fraction of Si3N4 powder in suspension. The results obtained from nanoindentation carry out lower values in comparison with the values measured by resonant frequency technique.
Influence of Carbon Nanotubes on the Mechanical Properties and Morphology of the Thermoplastic Polymer Matrix of the Polyamide 6
Authors: Vácha Jan
Published: March 2014

This paper examines mechanical properties of composites with thermoplastic polymer matrix and carbon nanotubes. Polyamide 6 was used as a basic matrix, to which nanoparticles in the form of nanotubes were added in a described proportion to the weight. Granulate was prepared by cold granulation in the worm extruder. Dried granulate was injected into the Arburg injection molding machine. Mechanical properties were evaluated by tensile and hardness test. These results were then compared with results achieved by polyamide 6 to which no fillers were added. Discussion analyses what is the influence of nanotubes fillers on crystallinity degree of the polymer matrix of polyamide 6. Conclusion evaluates and compares influence of presence of fillers on the mechanical properties of polypropylene matrix.
Local Viscoelastic Properties of a Thermoplastic/Carbon Laminate as an Indicator of Fatigue Damage
Authors: Minster Jiří , Šperl Martin , Lukeš Jaroslav
Published: March 2014

The paper is aimed at an assessment of influence of damage accumulation in a thermoplastic/carbon laminate during a tensile cycling loading on durability, Young modulus and both instant and time-dependent local mechanical characteristics of a thermoplastic matrix, analysed by means of instrumented microindentation. Standard mechanical data from three-point bending are compared with results of the local microindentation testing.
Instrumented Indentation of Composite Materials Prepared by Methods of Mechanochemistry
Authors: Balko Ján , Hvizdoš Pavol , Córdoba José Manuel , Chicardi Ernesto
Published: March 2014

Four materials TixTa1-xCN-20%Co of two chemical composition (x=0.9 and 0.95) and two high energy milling methods have been prepared. Nanoardness and elastic modulus for microstructure as a whole and both phases (matrix and hardmetal grain) were obtained (Tab. 1). Instrumented indentation was cerried out on the nanoindentation equipment TTX NHT (CSM instruments). Single load mode was used. Maximum applied loads of 20 and 50 mN for individual phases and 300 mN and 400 mN for microstructure as a whole were used.
Mechanical Properties of Rubber Samples
Authors: Skrobak Adam , Stanek Michal , Manas David , Ovsik Martin , Senkerik Vojtech , Reznicek Martin
Published: March 2014

This article demonstrates what influence has a change in production technology on mechanical properties of rubber testing samples. It compares two basic production technologies compression molding and injection molding. The aim of this research is to show and evaluate to what extent the properties (tensile strength, extension, tear strength and microhardness) are influenced by the used production technology and to quantify this potential difference on the basis of standard tests. The mechanical tension test according the standard ISO 37, the test determining tear strength according to the standard ISO 34-1 and the instrumented microhardness test (DSI) according to the standard ISO 6507-1.
Micro-Hardness and Morphology of LDPE Influenced by Beta Radiation
Authors: Ovsik Martin , Kratky Petr , Manas David , Manas Miroslav , Stanek Michal , Bednarik Martin
Published: March 2014

This article deals with the influence of different doses of Beta radiation to the structure and mico-mechanical properties of Low-density polyethylene (LDPE). Hard surface layers of polymer materials, especially LDPE, can be formed by radiation cross-linking by β radiation with doses of 33, 66 and 99 kGy. Material properties created by β radiation are measured by micro-hardness test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the LDPE tested. The highest values of micro-mechanical properties were reached at radiation dose of 66 and 99 kGy, when the micro-hardness values increased by about 21%. The changes were examined and confirmed by X-ray diffraction.
Nanohardness of Electron Beam Irradiated Polyamide 6.6
Authors: Manas David , Ovsik Martin , Manas Miroslav , Stanek Michal , Kocman Karel , Bednarik Martin , Kratky Petr
Published: March 2014

Nanomechanical changes in the surface layer of polyamide 6.6 modified by beta radiation were measured by instrumented test of nanohardness. The specimens were prepared by injection technology and subjected to radiation doses of 0, 33, 66, 99, 132, 165, 198kGy. Measurements of nanohardness showed considerable changes of behavior of surface layer in middle as well as high radiation doses with higher values of indentation hardness and stiffness.
Particulate Composite Damage: Numerical Estimation of Micro-Crack Paths
Authors: Majer Zdeněk , Hutař Pavel , Ševčík Martin , Náhlík Luboš
Published: March 2014

The composites are widely used due to their advanced mechanical properties. Particulate composites with polymer matrix were studied with regard to micro-crack propagation in the matrix. A three phase numerical model was created. Linear elastic material properties of particle and matrix were taken from experiment. Using numerical simulations (based on the finite element method) the influence of interphase properties on micro-crack propagation was studied. The results of this paper can contribute to a better understanding of the micro-crack propagation in the particulate composites with respect to the interphase.
Effect of Boriding Time on Microstructure and Residual Stresses in Borided Highly Alloyed X210CR12 Steel
Authors: Pala Zdenek , Mušálek Radek , Kyncl Jiří , Harcuba Petr , Stráský Josef , Kolařík Kamil , Ganev Nikolaj , Matějíček Jiří
Published: March 2014

Boriding of highly alloyed steels done with the aim of increasing their wear resistance faces several issues connected with the microstructure of the base material and restraints during the diffusion of boron. The aim of the performed analyses was to ascertain whether significant increase of boriding time can enhance the surface hardness, contribute to creation of more compact microstructure and even lead to beneficial state of residual stresses in the borided layer. Using combination of X-ray diffraction and electro-chemical polishing, residual stress depth distributions in few tens of micrometres thick borided layers were obtained.
Prediction of Tensile Properties Based on Hardness Measurement
Authors: Zubko Pavol , Pešek Ladislav
Published: March 2014

The contribution deals with prediction of tensile properties based on measurement of microhardness. First of all, the database of stress strain, s-e vs. hardness data was created. Tensile strength, yield strength, ductility and parameters of Ludwig-Hollomon equation σ = σ0+kεn ; k, n were correlated with hardness. Various hardness values found in literature were recalculated to Brinell hardness. In tensile testing measured s-e curves were compared with that obtained from the correlation. The investigated materials were API 5 L grade steels X70 after different deformation exposition. The results give good agreement between compared data. The most difference between estimated and measured curve is in area of yield strength, because of Lüders deformation on investigated steel.
Densification as the Only Mechanism at Stake during Indentation of Silica Glass?
Authors: Keryvin Vincent , Gicquel Solene , Charleux Ludovic , Guin Jean Pierre , Nivard Mariette , Sangleboeuf Jean Christophe
Published: March 2014

Silica glass is known to exhibit permanent changes in density under very high pressures. These changes may reach 21%. The sharp indentation test develops pressures underneath the indenter that trigger densification. Recently, we have proposed a constitutive modeling of the pressure-induced process accounting for its salient features: densification threshold, hardening, saturation of densifica- tion and permanent increase in elastic moduli. We examine in this paper the possibility that densi- fication could be the only mechanism for creating an imprint by indentation. We consider different models with growing complexity that we implement in a finite element software. Results indicate that the combination of shear and pressure as a driving force to densification may account for the mechanical response of the indentation test as well as the presence of densified zone underneath the imprint.
Energy Aspects of Concentrated Contact and Instrumented Indentation
Authors: Menčík Jaroslav
Published: March 2014

The paper gives a brief overview of various energy approaches and possibilities they offer. Most of it is illustrated on examples from depth-sensing indentation. Components of contact work are listed, and the relationships between these components and material characteristics are given. Also the solution of impact problems is shown, based on the law of energy conservation. Finally, the role of surface energy and adhesion is mentioned.
A Numerical Study of the Effect of the Berkovich Indenter Orientation on the Elastic Response of Anisotropic Material
Authors: Materna Aleš , Haušild Petr
Published: March 2014

The effect of the grain orientation of the stainless steel AISI 304 and the effect of the indenter orientation on the indentation moduli was numerically studied by means of the finite element method. The contact areas were evaluated numerically and the indentation moduli was determined according to the Oliver-Pharr method. As a result, the crystallographic orientations in which the indenter orientation plays the most important role were identified. However, the observed indentation moduli variation is within the scatter of the experimental data in practical applications.
Constant Load Testing of Materials Using Nanoindentation Technique
Authors: Král Petr , Dvořák Jiří , Kvapilová Marie , Lukeš Jaroslav , Sklenička Vaclav
Published: March 2014

Experiments were conducted to evaluate creep behavior of conventional and ultrafine-grained metallic materials using nanoindentation technique. The polished surface of samples was loaded up to 5 mN. The load was held constant to examine the creep behavior. Nanoindentation tests were performed at room temperature. Strain rate was evaluated from load and displacement data. The stress exponents of strain rates n were determined from loading stress dependences of creep rate. The values of stress exponents of the indentation strain rate indicate that creep behavior of investigated materials is influenced in particular by slip of intragranular dislocations. By contrast, deformation mechanisms like grain boundary sliding and diffusion processes seem to be improbable.
Characterization of Local Stress-Strain Behavior in WWER 440 Weld and Base Metal by Instrumented Indentation Technique
Authors: Haušild Petr , Materna Aleš , Siegl Jan , Kytka Miloš , Kopřiva Radim
Published: March 2014

15Ch2MFA (base metal) as well as 10ChMFT (weld) steels used for WWER 440 nuclear reactor pressure vessel manufacturing present a gradient in mechanical properties through the wall thickness, which can hardly be assessed by conventional testing such as tensile or Charpy tests. Mechanical properties in the weld and base metal were therefore determined by performing a series of instrumented indentations across the weld at room temperature. The results were treated by so-called automated ball indentation technique. Local stress-strain behavior obtained by instrumented indentation was correlated to the tensile test data and microstructure characterized by metallographic analysis.
Influence of Drill Wear to Local Plastic Deformation in the Wall of Drilling Hole
Authors: Martinkovič Maroš , Pokorný Peter , Bodišová Petra
Published: March 2014

Final properties of plastic deformed parts of workpieces are affected by production technological processes. Therefore it is needful to know detailed structure changes of plastic deformed material caused by machining - grinding, drilling etc. Friction of tool to work surface caused one of three areas of plastic deformation in cutting zone. It has great influence to quality of work surface and local mechanical properties of surface layer of workpiece. Influence of drill wear to local plastic deformation in deformation zone around the surface of drilled holes was investigated. Two types of cutting tools were used: high speed steel drill IZAR HSSCO with diameter 6,0 mm surface hardened by boriding and the same one without boride layer. Standard cutting parameters were used. During the machining process, axial component of cutting force and torque were observed. The work piece was bulk from carbon steel Ck45 (1.0503). Wear of the tool was estimated as a wide of wear on tool flank. The local strain in analysed place of probes on their sections was obtained by stereological measurement of degree of grain boundaries orientation, which is proportional to grain boundaries deformation degree. Estimation of grain boundary orientation degree leads to determination of local plastic deformation in arbitrary place of workpiece. These results lead to detailed analysis of material structure changes caused by drilling from which local mechanical properties result.
Effect of Pile-Up on the Mechanical Characteristics of Steel by Depth Sensing Indentation
Authors: Burik Peter , Pešek Ladislav , Voleský Lukáš
Published: March 2014

Mechanical properties by depth sensing indentation are derived from the indentation load-displacement data used a micromechanical model developed by Oliver & Pharr (O&P). However, O&P analysis on the indentation unloading curve is developed from a purely elastic contact mechanics (sink-in). The applicability of O&P analysis is limited by the materials pile-up. However, when it does, the contact area is larger than that predicted by elastic contact theory (material sinks-in during purely elastic contact), and both hardness H and Youngs modulus E are overestimated, because their evaluation depends on the contact area deduced from the load-displacement data. H can be overestimated by up to 60 % and E by up to 30 % depending on the extent of pile-up [1,2]. It is therefore important to determine the effect of pile-up on obtained mechanical characteristics of the material by depth sensing indentation. The work experimentally analyses the effect of pile-up height on mechanical characteristics H and E, which are determined by O&P analysis. Pile-up height was measured by atomic force microscopy (AFM).
Verification of the Trend of MPL Variation in Fatigue by Modern Methods
Authors: Gajdoš Ľubomír , Šperl Martin , Frankl Jiří , Kaiser Jaroslav , Mentl Václav , Kyncl Jan , Lukeš Jaroslav , Kužel Radomír
Published: March 2014

The paper presents experimental results concerning the variation of microplastic limit (MPL) during fatigue as determined by the measurement of changes in inductance L of specimens made from normalized low-C steel CSN 411375. Some indications have been obtained that MPL varies during fatigue with dislocation density. This was proved by nanoindentation, X-ray diffraction and transmision electron microscopy.
Multifunctional Nanostructures: Synthesis and Applications
Authors: Chidambaram Siva , Baskaran Karthikeyan , Samuel Solomon J. , Pari Baraneedaran , Sujatha Annie R. , Muthusamy Sivakumar
Published: March 2014

Free identical nanoobjects include metals, semiconductors, magnetic materials, polymers, bio molecules, are integrated together to form as multifunctional nanomaterials (MFNs), in which more than one behaviour can be rendered simultaneously. This summary showcases their exciting properties which are providing the emerging properties in applications like visualizing and targeting in drug delivery, recoverable and reusable photocatalytic materials. Various application areas, where the multifunctional nanomaterials are now getting the constant place in cutting edge technologies, are highlighted. And also in this, various multifunctional materials and their criteria involving during the integration of assorted materials based on their properties and to be applied according to the requirements of the applications are also explained in detail.
DFT Simulation of the Extra Me Adatom Diffusion on the Ge(111) √3×√3 1/3 ML Me Induced Surfaces
Authors: Luniakov Yuri V.
Published: March 2014

A first-principle simulation of the surface diffusion of an extra metal (Me) adatom on the corresponding 1/3 monolayer (ML) Ge (111)√3×√3 Me induced surfaces has been performed. Using the Nudged Elastic Band (NEB) optimization method, the minimum energy paths and activation energy barrier profiles for all known Me inducing √3×√3 reconstruction on a Ge(111) surface have been obtained. The value of the activation barrier is shown to depend on the adatom formation energies and the atomic radius of the diffusing metal: 0.33 eV for Pb and 0.25 eV for Sn. The Arrhenius pre-exponential factors that were obtained in the harmonic approximation are as large as 1011-12Hz for all of the investigated surfaces, which supports the single-atomic diffusion model considered here.
Growth of Na2W2O7 Single Crystals as Possible Optical Host Material
Authors: Gavrilova T.A. , Ivannikova N.V. , Shlegel V.N. , Grigorieva V.D. , Solodovnikov S.F. , Bekker T.B. , Atuchin V.V.
Published: March 2014

High-quality Na2W2O7 single crystals have been grown by low temperature gradient Czochralski technique (LTG Cz). The phase purity of grown crystals has been verified by XRD analysis. A set of oxide compositions based on Na2W2O7 and doped with Ce and special additions for charge compensation has been prepared by solid state synthesis. The formation of Na2W2O7-based solid solutions is found at as high Ce content as ~ 5 mol%.
Study of Biopolymer Chitosan as Resist for Submicron Electronic Lithography
Authors: Voznesenskiy Sergey S. , Nepomnyaschiy Aleksandr , Kulchin Yuri N.
Published: March 2014

This paper presents the results of the study of polysaccharide chitosan as a new resist for electronic lithography for direct formation of mesostructures in submicron range. Film-forming properties of chitosan allow enough simply to obtain coatings with a thickness of tens to hundreds of nanometers. Furthermore, the optical and sensor characteristics of the films of various ionic forms of chitosan are well investigated, so it makes possible to form on their basis integrally optical functional structures.
Photodynamic Effects in Nanocomposites Based on Quantum Dots of Cadmium Sulfide Embedded in a Silicate Matrix, in their Interaction with the Laser Beam
Authors: Sergeev Alexander A. , Voznesenskiy Sergey S. , Galkina Anna N. , Nepomnyaschiy Aleksandr , Sergeeva Kseniya M.
Published: March 2014

In this paper we study the possibility of modifying the optical properties of nanocomposites based on CdS quantum dots embedded in a silicate matrix, in their interaction with the laser radiation. It was found that the action of laser radiation leads to local change in the refractive index of the nanocomposite, the dynamics of which depends on the exposure conditions.
The Optical Spectra of a-Si:H and a-SiC:H Thin Films Measured by the Absolute Photothermal Deflection Spectroscopy (PDS)
Authors: Remes Zdenek , Vasudevan Ravi , Jarolimek Karol , Smets Arno H.M. , Zeman Miro
Published: March 2014

The new absolute PDS setup allows to measure simultaneously the absolute values of the optical transmittance T, reflectance R and absorptance A spectra in the spectral range 280 2000 nm with the typical spectral resolution 10 nm in ultraviolet and visible spectral range and 20 nm in the near infrared region. The PDS setup provides the dynamic detection range in the optical absorptance up to 4 orders of magnitude using non-toxic liquid perfluorohexane Fluorinert FC72. Here we demonstrate the usability of this setup on a series of intrinsic as well as doped a-Si:H and a-SiC:H thin films deposited on glass substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (CVD) from hydrogen, silane and methane under various conditions. The increase of the Tauc gap with increasing carbon concentration in intrinsic a-SiC:H was observed. The defect-induced localized states in the energy gap were observed in doped a-Si:H as well as undoped a-SiC:H below the Urbach absorption edge.
Near-Field Optical Probe Based on the Fiber Fabry-Perot Interferometer with Protruding Evanescent Light Source
Authors: Kuchmizhak Aleksandr A. , Vitrik Oleg B. , Kulchin Yuri N.
Published: March 2014

We studied numerically and experimentally the possibility of the development of a novel probe based on the fiber Fabry-Perot interferometer with an evanescent light source protruding directly toward the sample. It was shown that such probe provides a spatial resolution ~λ/40 for λ=1550 nm. The fabrication process of such a probe is described in detail.