bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods to Reduce the Operating Temperature of Photovoltaic Cells
Authors: Hysek Peter
Published: January 2016

The article includes an overview of the effectiveness of different generations of photovoltaic cells, the temperature dependence of the electrical efficiency and methods of integration into the building envelope. Furthermore, the article focuses on experimental and simulation of proven methods to reduce the operating temperature of photovoltaic cells.
An Optimal Window Position in External Walls, of Different Materials and Construction Designs, in Relation to Critical Surface Temperature
Authors: Vavrovič Boris , Menďan Rastislav
Published: January 2016

In article analysis of optimal window position in external wall of different properties is provided, considering the highest surface temperature in contact area of window and its reveal.
Thermotechnical Properties of Unburnt Clay Wall in Historical Family House and Wall Reconstruction
Authors: Menďan Rastislav
Published: January 2016

Article describes the problem of heat cladding in family houses built from unburnt clay, that do not represent listed buildings and had already undergone various reconstructions (restorations). Presented are measurements of basic thermotechnical properties of clay wall in historical family house and analysed is fragment of clay wall in its original condition and after renovation, considering building heat engineering requirements.
Hygrothermal Initial Conditions - Case Studies
Authors: Zozulák Marek , Vertaľ Marián , Katunský Dušan
Published: January 2016

In building simulations initial conditions express the actual hygrothermal state of building envelope. For the temperature field simulations initial condition is represented by the initial temperature in the body profile at the start of heat transfer. In-structure temperature varies quickly so temperature initial conditions are often neglected. The contribution shows various temperature initial conditions determination for insulated construction of outdoor test cell. We confirmed importance of setting the initial moisture condition for numerical analysis of complex heat and moisture transfer in multi-layer building components. Comparison of measured and calculated temperature profiles in structure show correctness initial condition consideration.
Physical Analysis of Water Vapour in Function Gap
Authors: Palko Milan , Palková Adela
Published: January 2016

The article is focused on the physical analysis of water vapour in functional gap. The creation of condensate (respectively frost) in the cavity is not treated by norms or regulations. The level of importance of condensation is different depending on the material basis. In case of wooden window constructions, the surface treatment is degraded and their technical-physical features. The primary reason of condensation is transfer of humidity through the cavity between the window casement and its frame at reaching the temperature of dew point. The transfer causes: the difference of air pressures (which drifts vapour) – infiltration and exfiltration and diffusion of vapour (different saturation of vapour in external and internal air, diffusion flux is, under certain circumstances, able to flow in a different direction than airflow).
Quality of Vapour-Proof Layer Concept in Roof Envelope in Residential Attics
Authors: Jakeš Erik
Published: January 2016

Vapour-proof layer in roof envelope of residential attic has dominant position in terms of moisture regime. It has significant impact on quality and proper functioning of the remaining layers mainly the thermal insulation. The paper points out on the mounting defects in vapour-proof layer installations which occur chiefly due to poor realization during construction. The defects are often ignored, underestimated and their acceptance at earlier and later stages causes serious failures affecting the housing quality.
The Impact of Relative Position of the High-Rise Buildings on the Wind Flow
Authors: Čeheľová Dagmara , Janák Milan , Bielek Boris
Published: January 2016

The Venturi effect has been defined as the increase in fluid speed or flow rate due to a decrease of the flow section. In the present paper the wind speed conditions in passages between triangular buildings with different distances are studied with Computational Fluid Dynamics (CFD) to investigate the extent to which the Venturi effect is present in the passages. In this paper are considered eight different variants of relative positions of the two high-rise buildings. The variable is a distance between towers. They are investigated maximum wind velocities and the point at which the maximum velocity occurs for each from these variants.
Determination of Fire Resistance of Ceiling Structure Variant Design on the Basis of Timber Using Numerical Calculation Methods
Authors: Leško Róbert , Lopušniak Martin
Published: January 2016

Ability to resist of high temperature impacts during fire is not based exclusively on ignitability of building materials. At the present time, fire resistance is declared mainly through fire tests, but numerical procedures for the determination of fire resistance also represent an effective alternative in this field. Using calculation methods for the determination of ceiling structure fire resistance on the basis of timber is subject of the submitted paper. The main objective of this paper is to demonstrate the fact that timber, or products from it, are building materials capable to resist impacts of fully developed fire for the period of more than 60 minutes in spite of their flammability. Applicability of these results in selected countries of Europe can be seen from the list of requirements.
Theoretical Determination of Sound Reduction Index of Simple Walls on Various Material Bases
Authors: Pavčeková Monika , Menďan Rastislav
Published: January 2016

The contribution deals with a comparison of measured and calculated values of sound reduction index R (dB) and weighted sound reduction index Rw (dB) of simple walls from various materials. In this way it verifies the exactness of a modified calculation-graphic method according to Watters and an appropriateness of its application for simple walls from various materials with the focus on the aerated concrete walls.
The Design Principle Cladding of Internal and External Walls and the Architectural Design Analysis
Authors: Pernišová Alena
Published: January 2016

Design and implementation of surface treatments of individual bounding surfaces of the Interior should be in symbiosis. The interior is perceived as a functional unit, in which the coating of walls, ceiling and floors together with the furniture and other accessories create a particular style of the enclosed space. Surface treatments of facades give the building a unique architectural expression. A large group of facade finish represents mounted cladding. In practice they are widely used and are part of almost every object. They participate in the aesthetic appeal of the external environment and buildings from the architecture point. Cladding as part of the external walls affects its structural and physical properties and because of its coverage opacity they allow to use new, highly effective thermal insulation of the external walls.
The Effect of a Front Frame on the Increase in Sound Insulation of an Acoustically Simple Wall - Results of On-Site Measurements
Authors: Dlhý Dušan , Tomašovič Peter , Petrák Peter , Zaťko Peter
Published: January 2016

The experience of performed measurements of sound deadening of building structures in constructions sites shows a frequently occurring fact, which is that the walls separating living rooms of separate flats do not meet the required values under the standard. Contractors, designers, but often also the users of flats choose untrusted compositions of auxiliary constructions, whose effect is rather questionable.
Experimental Measurements of Effects of Occupancy Class on Reverberation Time
Authors: Dlhý Dušan , Zrneková Julia
Published: January 2016

Experimental measurements have been focused on the issue of change in reverberation time T20 and T30 (s) in a selected room (classroom) due to its occupancy by persons (students) and changes in reverberation time T20 and T30 (s) as a result of the excitation signal during measurement. Reverberation time was measured in a standard room at the Faculty of Civil Engineering of the Slovak Technical University in Bratislava (classroom B318) by the use of NORSONIC (NORSONIC NOR 280 amplifier, an omnidirectional sound source - NORSONIC NOR 270, NORSONIC TYPE 118, and microphone and preamplifier). The room (classroom B318) was selected as a model classroom in terms of its dimensions, i.e. volume (225 m3), arrangement of furniture, and maximum number of students during standard lectures (up to 24 people). The main task of this study was the inter-comparison of measurement results of reverberation times T20 and T30 (s), with regard to room occupancy of students (100%, 50%, 0%), the position of students (sitting and standing), and the excitation signal (pink noise, white noise, impulse - bursting of an inflated balloon).
Effects of the Sound Insulation of the Outer Structure on the Price
Authors: Dlhý Dušan , Tomašovič Peter
Published: January 2016

Manufacturers indicate sound insulation of envelope structures of different materials. Acoustical properties of manufactured openings as windows and doors (plastic, wooden, metallic) are known. Following theoretic relations for calculation of consequential sound insulation of acoustic composite wall Rw, it is possible to work out options of walls and openings of various materials.
Proposal of Architectonic – Construction Solution of Barrier-Free Measures of Entry Premises in Non-Residential Buildings Specified for Use by the Public
Authors: Pernišová Alena
Published: January 2016

Barrier-free environment should be an obvious part of our life. The reality is but different. In non-residential buildings specified for use by the public one can uselessly look for information useful for persons with limited ability of movement and orientation. The question of information boards is very disregarded and often non-dealt with at all. Upon entry into most of the buildings you will not find any optical system for deaf people, acoustic system (voice light) for blind people or information related to barrier-free access for people with movement handicap. Project engineer, upon performing his work has to take into consideration the fact that building being designed shall be used by all groups of citizens. Try to look around with eyes of a person who moves on wheelchair or through a walking stick. You will find missing information and orientation system on possibilities of barrier-free movement inside the building on each and every building.
Drainage Systems for Sloping Roofs and Possibilities of Rain Water Use
Authors: Pernišová Alena
Published: January 2016

The roof represents an inevitable part of each building. From the architectonic and construction point of view it completes its shape solution and serves an important role of a protective cover. It has to fulfil its protective function without failures and deformations. Shape, construction and material solution of roof deck must go hand in hand with safe method of roof drainage. Correctly drained roof is the basic prerequisite of the whole structure operation. The main and primary role of the drainage system lies in drainage of rain water in as fast and safe method as possible from the roof into the sewage system or absorbing system. Rain water is not a drinking water, but it is clean water which can be used for various purposes in the household.
Glass Fibre Reinforced Concrete Products for Construction Industry and Architecture
Authors: Jakeš Erik
Published: January 2016

Glass fibre reinforced concrete is a material which found its undisputable place in architecture and construction industry. Architecture has been using its creativity potential at building atypical elements of a specific building and the needed detail. This specific material enables unusual geometrical shapes, curves and surfaces. It is able to create custom-made original works. It is not a material which is used to make the products competitive with their price and serial production etc. It wants to be original, offers new challenges and provide new forms of its application to the people. The paper describes selected glass fibre reinforced concrete products which can serve as examples of new components creation to the producers and architects.
Modelling and Analysis of High Strain Rate Deformation at Elevated Temperature in Friction Stirring of Aluminum Alloys
Authors: Kumai Katsuya , Fukushige Hiroki , Takayama Yoshimasa
Published: January 2016

Friction stirring is a fundamental process in the friction stir welding (FSW), and moreover, high strain rate deformation in elevated temperature to lead to extremely high ductility and fine grain size. In the present study, friction stirring process has been successfully modelled as a high temperature deformation depending on strain rate and temperature, assuming shear deformation of material in stir zone and generation of frictional heat by rotating tool. Axial load and torque during the process were estimated based on the model, and compared with the experimental data at two kinds of combination ratio in FSW of aluminum and Al-Mg alloy. It was, consequently, confirmed that the model could evaluate flow stress and strain rate from the experimental load and torque.
The Effect of α-Phase Grains Morphology in Initial Microstructure on Superplasticity of Two-Phase Titanium Alloys
Authors: Motyka Maciej , Sieniawski Jan
Published: January 2016

It is generally accepted that fine-grained and equiaxed microstructure enables superplastic deformation of two-phase titanium alloys. Appropriate microstructure is usually developed in the thermomechanical processing with careful selection of the parameters of plastic deformation and heat treatment. Based on results of own research in this area increased superplasticity was found in Ti6Al4V alloy having microstructure containing highly deformed and elongated α-grains – considerably different from equiaxed ones. It was found that during heating up and first stage of superplastic deformation fragmentation of elongated α-phase grains occurred, followed by formation and growth of globular grains of that phase. Particular role of quenching of the Ti6Al4V alloy from the stable β-phase temperature range in thermomechanical processing was identified. It leads to increase of elongation coefficient of α-phase grains after plastic deformation but also restrains nucleation of the precipitates of secondary α-phase in further stages of thermomechanical processing. It was established that developed phase morphology of the alloy determined its hot plasticity – especially in the range of low strain rates typical for superplastic deformation.
Hot Forming Process Analysis of Ti6Al-4V Alloy: Experiment, Behaviour Modelling and Finite Element Simulation
Authors: Velay Vincent , Matsumoto Hiroaki , Vidal Vanessa , Penazzi Luc , Nazaret Fabien , Marcel Yves , Bouillane Maxime
Published: January 2016

The present investigation aims at evaluating and understanding the thermo-mechanical be-haviour of a titanium alloy under hot forming conditions. In this work, several considerations are ad-dressed. First, Scanning Electron Microscopy observations are performed to assess the evolutions of(α − β) phases, grain size, defects regarding the thermo-mechanical loadings from different static anddynamic tests (various temperatures and strain rates). Hence, the relationships between mechanicalproperties and micro-structure evolutions in such conditions allow a first assessment of the deforma-tion mechanisms in link with the macroscopic stress-strain curves. Afterwards, a behaviour modelformulation associated to an identification procedure of the parameters of the constitutive equationsis proposed. Finally, several tests performed under hot forming conditions and conducted on an in-dustrial press are compared to Finite Element calculations. Results are compared and provide someinteresting improvement ways in order to investigate the influence of the process parameters on thefinal shape of the part.
Development of Al-Mg Alloys with Different Levels of Mn and Fe for Super-Plastic Forming
Authors: Pushkareva Irina , Jin Hai Ou
Published: January 2016

New Al-Mg alloys have been developed for super-plastic forming (SPF) based on commercial AA5083/AA5086 alloys, but with an increased Mn content from 0.5 to 1.5 wt.% and a decreased impurity Fe level from 0.25 to 0.05 wt.%.The effects of Mn and Fe levels on super-plasticity have been investigated by high temperature tensile testing of cold rolled H18 sheets at 425 to 525°C with a strain rate of 2×10-3 s-1. The microstructure evolution during different processing stages, grain size and grain size stability were investigated by optical microscopy and scanning electron microscopy. Both Mn and Fe showed a similar and significant contribution to grain size control in recrystallization, but their effect on high temperature sheet formability was different. An increase in Mn level led to an improvement in high temperature tensile elongation, while an increase in Fe content reduced the sheet formability. A new alloy with 1.5 wt.% Mn and 0.05 wt.% Fe, when processed to H18 temper, was able to reach more than 400% tensile elongation at 450 - 500°C with a strain rate of 2×10-3 s-1.
Advances in Superplasticity of Ultrafine-Grained Alloys: Recent Research and Development
Authors: Valiev Ruslan Z. , Semenova Irina P.
Published: January 2016

Recent studies have revealed that ultrafine-grained (UFG) metals and alloys produced by severe plastic deformation (SPD) can demonstrate extraordinary superplasticity at low temperatures and/or high strain rates. This work presents new results on superplasticity in several UFG Al and Ti alloys focusing on microstructural evolution and strain hardening, as well as the challenges of their application. Grain refinement in these alloys was accomplished using severe plastic deformation techniques, including new modifications of equal channel angular pressing (ECAP). Unusual behavior of UFG alloys originates both from the formation of ultrafine grain by SPD processing as well as the state of grain boundaries in these materials. It is established that superplastic deformation allowed not only to attain their efficient forming, but also to improve the ultrafine-grained structure and to obtain enhanced mechanical properties in the articles produced. The results demonstrate the possibilities of new applications of superplastic forming using bulk nanostructured materials.
Forty-Five Years of Superplastic Research: Recent Developments and Future Prospects
Authors: Langdon Terence G.
Published: January 2016

Although superplasticity has a long history, dating back to the first laboratory-scale observations in 1934, the major new developments in superplasticity have occurred almost exclusively over the last four decades. Furthermore, this corresponds to the period associated with the ICSAM conferences which started with a first conference in San Diego, California, in June 1982 and has continued to ICSAM-2015 in Tokyo, Japan. Major developments over this time include the growth of a vibrant and effective superplastic forming industry and an extension of the concept of metallic superplasticity to include both ceramics and geological materials. This paper examines the significance of these developments and discusses future prospects and new opportunities within the field of superplastic research.
On Regularities of Grain Refinement through Large Strain Deformation
Authors: Belyakov Andrey , Yanushkevich Zhanna , Tikhonova Marina , Kaibyshev Rustam
Published: January 2016

The recent studies on grain refinement in austenitic stainless steels during large strain deformations are critically reviewed. The paper is focused on the mechanism of structural changes that is responsible for the development of submicrocrystalline structures that can be interpreted as continuous dynamic recrystallization developing under conditions of warm working. The final grain size that is attainable by large strain warm working can be expressed by a power law function of temperature compensated strain rate with an exponent of about -0.15. The development of submicrocrystalline structures is assisted by the deformation microbanding and dynamic recovery, which are characterized by opposite temperature dependencies. The grain refinement kinetics, therefore, are characterized by a weak temperature dependence for a wide range of warm working conditions.
Superplastic Behavior of Friction-Stir Welded Joints of an Al-Mg-Sc Alloy with Ultrafine-Grained Microstructure
Authors: Malopheyev Sergey , Mironov Sergey , Vysotskiy Igor , Kaibyshev Rustam
Published: January 2016

The commercial Al-5.4Mg-0.2Sc-0.1Zr alloy was subjected to equal-channel angular pressing at 300°C to a true strain ~12 followed by cold rolling to a total thickness reduction of 80%. The ultrafine-grained sheets were joined by friction stir welding (FSW). To evaluate superplastic properties of the weldments, the tensile samples including all of the characteristic FSW microstructural zones were machined perpendicular to the welding direction and pulled up to failure in the temperature range of 400 to 500°C and at strain rates of 2.8×10-4 s-1 to 5.6×10-1 s-1. The friction-stir welded material exhibited excellent superplastic properties. The highest elongation-to-failure of ~1370% was recorded at a temperature of ~450°C and an initial strain rate of 5.6×10-2 s-1, where the strain rate sensitivity coefficient was about 0.64. The relationship between superplastic ductility and microstructure is discussed.
Improvement of Superplasticity in Fine-Grained Oxide Ceramics Based on the Concept of Grain Boundary Plasticity
Authors: Yoshida Hidehiro , Morita Koji , Kim Byung Nam , Matsui Koji , Ikuhara Yuichi , Sakuma Taketo
Published: January 2016

Superplasticity in fine-grained oxide ceramics has been generally elucidated on the basis of their experimental strain rate-flow stress relationship and phenomenological analysis of cavity nucleation and growth. It has been widely accepted that the high temperature superplastic flow and failure in ceramics is significantly influenced by the atomic structure and chemistry of grain boundaries. Such phenomenon cannot be explained based on the classical phenomenological analysis. Our research group has therefore proposed to establish a new research field, grain boundary plasticity, to describe the superplastic deformation related to the grain boundary atomic structure. This paper aims to point out the importance of the atomistic analysis of grain boundary to develop new superplastic ceramics.
Ultrafine-Grained Structure Produced by FSW and ECAP in Al-Mg-Sc-Zr Alloy: Comparison
Authors: Kulitskiy Vladislav , Malopheyev Sergey , Buranova Yulia , Divinski Sergiy V. , Wilde Gerhard , Kaibyshev Rustam
Published: January 2016

The Al-5.4Mg-0.2Sc-0.1Zr alloy with initial coarse grained structure and containing coherent nanoscale Al3(Sc,Zr) particles with an average size of ~9 nm was subjected to equal channel angular pressing (ECAP) at temperatures ranging from 300 to 450°C up to a total strain of ~12 and friction stir processing (FSP) with the rotation speed ranging from 350 to 800 rpm. ECAP led to the formation of a uniform microstructure with an average grain size of ~ 0.9 μm. Increasing deformation temperature leads to a slight increase in the average grain size to 1.4 μm and coarsening of Al3(Sc,Zr) precipitates to 13 nm. FSP with a tool rotation speed of 350, 500, 650, 800 rpm and traveling speed of 75 mm/min led to the formation of fully recrystallized uniform microstructures with an average grain size of ~1.6, 1.9, 2.7 and 2.9 μm, respectively. The coarsening of Al3(Sc,Zr) dispersoids from 9 to 27 nm occurred under FSP but most of them retained coherency with the matrix.
Ultrafine-Grained Structure and Mechanical Properties of a High-Mn Twinning Induced Plasticity Steel
Authors: Kusakin Pavel , Belyakov Andrey , Kaibyshev Rustam , Molodov Dmitri
Published: January 2016

The influence of thermo-mechanical treatment consisting of cold rolling followed by recrystallization annealing on the grain size and mechanical properties of a high-Mn TWIP steel was studied. An Fe-23Mn-0.3C-1.5Al TWIP steel (wt. %) was subjected to extensive cold rolling with a reduction of 80% (true strain of ∼1.6) and then annealed in the temperature interval ranging from 400 to 900 °C during 20 minutes. Recovery processes took place below 500 °C, partial recrystallization was evident at ~550°C and fully recrystallized structure evolved after annealing at 600 °C and higher. The static recovery resulted in a slight decrease in the yield strength from 1400 MPa to 1250 MPa and the ultimate tensile strength from 1540 MPa to 1400 MPa whereas the total elongation of 4% did not changed. The recrystallization development led to a drastic drop of strength and an increase in ductility. The yield strength of 225 MPa, the ultimate tensile strength of 700 MPa and the total elongation of 79% was obtained after annealing at 900 °C. Correspondingly, the grain size increased from 0.2 μm to 6.2 μm with increase in anneal temperature from 550 to 900°C.
Formation of Ultrafine-Grained Structures in 304L and 316L Stainless Steels by Recrystallization and Reverse Phase Transformation
Authors: Odnobokova Marina , Belyakov Andrey , Kipelova Alla , Kaibyshev Rustam
Published: January 2016

The microstructure evolution and mechanical properties of 316L and 304L austenitic stainless steels subjected to large strain cold bar rolling and subsequent annealing were studied. The cold working was accompanied by mechanical twinning and strain-induced martensitic transformation. The latter was readily developed in 304L stainless steel. The uniform microstructures consisting of elongated austenite and martensite nanocrystallites evolved at large total strains, resulting in tensile strength above 2000 MPa in the both steels. The subsequent annealing at temperatures above 700°C was accompanied by the martensite-austenite reversion followed by recrystallization, leading to ultrafine grained austenite.
Development of Fine-Grained High-Mn Steelby Cold Rolling and Annealing
Authors: Yanushkevich Zhanna , Belyakov Andrey , Kaibyshev Rustam , Haase Christian , Molodov Dmitri A.
Published: January 2016

The regularities of static recrystallization in an Fe-0.3C-17Mn-1.5Al TWIP steel subjected to cold rolling and annealing were studied. The cold rolling led to noticeable increase in the dislocation density, extensive mechanical twinning and shear banding. The subsequent annealing resulted in the development of recovered or recrystallized microstructure depending on the rolling reduction and the annealing temperature. An increase in the rolling reduction promoted the recrystallization development, which led to ultrafine-grained microstructure with a grain size below 10 μm. The developed ultrafine-grained steel samples are characterized by beneficial mechanical properties.
Austenite Grain Size Refinement of Multi-Microalloyed Low Carbon Steel Using Severe Plastic Deformation at High Temperature
Authors: Kong Xiang Wei , Sui Tian Zhong , Hu Zhi Yong
Published: January 2016

The effect of hot deformation behavior on austenite grain size refinement of low carbon multi-microalloyed steel was investigated. The morphology of austenite grains was revealed by thermal etching and observed using optical microscope. The results showed that single pass compression can only marginally refine austenite grain size by dynamic recrystallization, even under severe plastic deformation. However, when the specimens were held for a while after hot deformation, the fine austenite grain size can be obtained due to static recrystallization behavior.
A New Lead-Free Solder Joint Utilizing Superplastic Al-Zn Eutectoid Alloy for Next Generation SiC Power Semiconductor Devices
Authors: Onuki Jin , Saitou Akane , Chiba Akio , Tamahashi Kunihiro , Motohashi Yoshinobu , Kawamata Yuji
Published: January 2016

A new high-temperature lead-free solder joint which withstands up to 300°C utilizing superplasticity in the Al-Zn eutectoid alloy has been developed to realize SiC power semiconductor devices. The new solid state joining process consists of interfacial cleaning of joints utilizing superplasticity of the Al-Zn-eutectoid alloy at 250°C followed by diffusion bonding between 350 and 390°C. The bonding strength of the new joints exhibits almost the same value at the temperature range from RT to 300°C, above which it decreases slightly with increasing temperature. It is also found that the bonding strength of the new joints is 8 times as high as those of a high-temperature Pb-5wt%Sn-1.5wt%Ag solder and the Al-Zn eutectoid alloy solder without utilizing superplasticity at 250°C. The Al-Zn eutectoid alloy solder joint has shown high reliability in the temperature cycle testing between 50°C and 300°C up to 300 cycles.
Titanium Superplastic Forming by Aurock: A Complete Integrated Solution from CAD File to Final Part
Authors: Barrau Olivier , Nazaret Fabien , Le Fournier Marion , Lebard Etienne , Lemaoult Yannick
Published: January 2016

With its experience in the SPF simulation and tool manufacturing, Aurock completes its offer in the titanium SPF field with the part forming and brings a global support from the conception up to the manufacturing. Aurock proposes tool design, forming strategy and simulation, rapid tool manufacturing made of refractory castable reinforced with metallic fibre and now titanium superplastic forming. To improve its offer, Aurock started from a blank page and developed a specific SPF press to test and assess new heating solutions. One major innovation permits to reduce the heating time using a direct sheet heating. The process becomes anisothermal. This approach avoid time to heat up to 900°C large toolings. The completed offer for titanium SPF parts and successful results on the heating solutions are presented.
Hybrid Superplastic Forming of Non-Superplastic AZ31 Mg Alloy
Authors: Guo Mei Ling , Tan Ming Jen , Song Xu , Chua Beng Wah
Published: January 2016

In this work, magnesium alloy sheets of non-superplastic grade AZ31 were successfully formed by a proposed hybrid superplastic forming at 400 °C within 22 min. During the forming process, hot drawing first formed the part partially from the starting metal sheet within a few seconds, and then followed by a designed gas forming process to achieve the desired conical shape by high gas pressure at a targeted strain rate. The maximum thinning of 59 % was found to occur at the first contact area between the material and the punch. The thickness distribution and superplastic deformation behavior during the hybrid superplastic forming were investigated. In addition, the microstructure evolutions of AZ31 at different forming stages were examined by electron backscatter diffraction. Superplastic forming capability of the non-superplastic grade magnesium alloy was achieved. Furthermore, the part formed by this superplastic-like forming was done faster and attained a more even material distribution than conventional superplastic forming.
The Superplastic Properties and Microstructures Evolution of High Nb Ti3Al Based Alloy
Authors: Han Xiu Quan , Fu Ming Jie
Published: January 2016

The superplasticity of high Nb Ti3Al based alloy - Ti-23Al-17Nb (at.%) alloy sheet under the conditions of 940~1000°C and 5.5×10-5s-1~1.7×10-3s-1are studied. The results show the elongation changes as a parabola with the deformation temperature increasing, and the maximum elongation obtained at 960°C and 5.5x10-5s-1 is 1447.5%. Work hardening stage increases much more than softening stage when strain rate is decreased due to the increasing of element Nb. Compared with primary microstructure, the lath-like α2 grains gradually disappeared, the α2 grains became more equiaxed, and the content and size of α2 grains are decreasing with increasing of deformation temperature. The volume fraction ratio of α2 and β phase at the optimum deformation condition is 50:50%. The cavities mechanism at the fracture tip was discussed; it can be defined that the cavities could be avoided when deformation temperature is higher than 940°C.
Innovative Methods for Investigating Key Process Variables in the Manufacture of Superplastically Formed Aero-Engine Components
Authors: Zuelli Nicola , Fleming Christopher , Farrell Mark , Zante Remi , Robinson Luke
Published: January 2016

A broad research programme was conducted at the Advanced Forming Research Centre to study the impact of key process variables in the manufacture of superplastically formed aero-engine components. The paper highlights the innovative methods adopted to investigate the factors affecting SPF process cycle-time, tool/component instrumentation for in-process measurements, and tool life. An extensive programme of forming trials conducted on a large press on real-scale components was performed to closely monitor key process parameters and understand their influence on the component inflation and cycle-time. Advanced experimental trials were conducted by instrumenting components and tool to analyse process variable live measurements in the harsh environment of the press during the SPF process. An extensive investigation of the chemical and physical interactions at the tool/component interface and their influence on surface finish and tool life was also conducted by using a range of specialised equipment and a custom-built SPF simulator.
Promises of Low-Temperature Superplasticity for the Enhanced Production of Hollow Titanium Components
Authors: Kruglov Alexey , Lutfullin Ramil , Mulyukov Radik , Mukhametrakhimov Minnaul , Rudenko Oleg , Safiullin Rinat
Published: January 2016

Application of the conventional superplasticity (SP) allows producing the unique hollow structures. One remarkable example is the hollow titanium blade of the air engine fan produced by Rolls-Royce. However, high temperature titanium alloys processing (~ 927 °С) limits wide industrial application of the conventional SP. The solution of the mentioned issue can be found through the application of low-temperature SP. Ti-6Al-4V alloy with ultrafine grain structure at the temperature range of 600 ­ 800 °С has enough ductility resources for the superplastic forming (SPF) of the parts with the complicated shape. The formation of pores in Ti-6Al-4V alloy at uniaxial and biaxial tension at the temperature 600 °С is not observed. The effect of low-temperature SP also allows lowering pressure welding (PW) temperature essentially. Herewith, there is a possibility to produce the hollow parts by the combination of SPF and PW. The main goal is the optimization of the technological scheme and processing temperature. The use of the low-temperature SP provides high quality of hollow components such as blades.
Superplastic Deformation Mechanisms in High Magnesium Contenting Aluminum Alloy
Authors: Yakovtseva O.A. , Mikhaylovskaya Anastasia V. , Mochugovskiy A.G. , Cheverikin V.V. , Portnoy Vladimir K.
Published: January 2016

The evolution of surface, grains and dislocation structures during superplastic deformation was studied in Al–6.8%Mg–0.6%Mn–0.25%Cr alloy by SEM, EBSD, TEM techniques. The effective activation energy of superplastic deformation was calculated. Contribution of grain boundary sliding was defined during superplastic deformation. Low value of grain boundary sliding, significant dynamic grain growth in stress direction, high dislocations activity and permanent continuous formation of sub-grain boundaries during superplastic deformation were found.
Universality of the Phenomenology of Structural Superplasticity
Authors: Sripathi Sriharsha , Padmanabhan K.A.
Published: January 2016

The equation σ=Kέm, where σ is the applied stress, έ is the strain rate, K and m are material constants that depend on stress / strain rate, temperature and grain size is often used to describe structural superplasticity. The general shape of the logσ-logέ curve is sigmoidal. Based on limited data, it was suggested by us earlier that a universal σ-έ curve could exist in a properly normalized space. έ and m are normalized with respect to έopt and mmax, the strain rate at which m is a maximum and the maximum m value respectively. Here a multi-dimensional relationship involving σ/σopt-έ/έopt-m/mmax-ΔF0/kT-η/ηopt is developed; σopt corresponds to έopt, ΔF0 is the free energy of activation for the rate controlling mechanism, k the Boltzmann constant, T the absolute test temperature, η the (apparent) viscosity of the superplastic alloy and ηopt is the viscosity of the same alloy for m=1 in a dimensionless σ-έ space. Using data concerning many systems, the phenomenology of structural superplasticity in all classes of materials is shown to be unique.
Effect of Grain Boundary Segregation on Shear Deformation of Nanocrystalline Binary Aluminum Alloys at Room Temperature
Authors: Babicheva Rita , Dmitriev Sergey V. , Zhang Ying , Kok Shaw Wei , Zhou Kun
Published: January 2016

The paper studies deformation mechanisms of nanocrystalline (NC) pure Al and its binary alloys with various distributions of an alloying element which can be Co or Mg via molecular dynamics simulations. It is revealed that a shear deformation of the pure Al is associated with the grain boundary sliding (GBS) and their simultaneous migration. Mg atoms in grain boundaries (GBs) of an Al-Mg alloy lead to GBS which does not accompany with a grain growth, while the deformation process of the corresponding alloy with a random distribution of Mg is close to that for the pure Al. Unlike Mg, GB segregations of Co atoms detain both GBS and GB migration and result in high strength of an Al-Co alloy. On the contrary, the strength of the alloy with the Co atoms distributed randomly is very low due to the structure amorphisation leading to the ease of plastic flow.
Effect of Alkaline Treatment on Sawdust Reinforced High Density Polyethylene Composite under Wide Strain Rate
Authors: Jaya Haliza , OMAR MOHD FIRDAUS , Md Akil Hazizan , Ahmad Zainal Arifin , Zulkepli Nik Noriman
Published: January 2016

In this study, the alkali treatment of sawdust using different concentration of sodium hydroxide (NaOH) is performed. The purpose of this treatment is to improve the filler-matrix compatibility, thus, enhance the properties of tested specimens under various strain rate condition. The outcome shows the alkali treated sawdust did improve its surface roughness through reduction of sawdust diameter. With this increasing of surface roughness, it will enhance the compatibility between sawdust filler and HDPE matrix. For comparison purpose, the treated and untreated sawdust filler were reinforce in High Density Polyethylene (HDPE) matrix and have been test under static and dynamic loading using Universal Testing Machine (UTM) and Split Hopkinson Pressure Bar (SHPB) apparatus. The results indicate that the stiffness and compression strength properties were improved on treated sawdust composites for both static and dynamic loading compare to untreated sawdust composites.
Optical Properties Changes of Ternary Glasses: Gamma Irradiation Effect
Authors: Amat Azuraida , Mohamed Kamari Halimah , Che Abdullah Che Azurahanim , Ishak Mansor , Mustafa Iskandar Shahrim , Abdul Aziz Sidek
Published: January 2016

Research on tellurite based glass has become important because of it potential in photonic and shielding material. In this work, the changes of the optical properties of ternary tellurite glasses when radiated with 25kGy gamma ray dose were studied. Five glass samples, with composition [(TeO2)70 (B2O3)30]100-x (Bi2O3)x (where x = 5, 10, 15, 20 and 25 mol%) were prepared by melt quenching technique. The optical properties were studied by UV-Visible absorption. The X-Ray Diffraction (XRD) spectra result shows that all glass samples fit the amorphous state. The Fourier Transform Infrared Spectroscopy (FTIR) was used to explore the structural bonding in the prepared glass samples due to exposure. Gamma irradiation causes a profound change in the peak intensity as shown by FTIR spectra which is due to the breaking of the network bonding. Before gamma irradiation, the optical band gap, Eg value decreased from 2.50 eV to 2.30 eV with the addition of Bismuth content. The value kept decreasing (from 2.18 eV to 2.05 eV) following exposure to 25 kGy gamma irradiation due to the increase of non-bridging oxygen (NBO) and the increase of defect in the glass. The finding suggest that the glass with high content of Bi2O3 (25 Bi) give smallest Eg and show less changes (less defect) in FTIR spectra after gamma irradiation which indicate that this glass is more resistant to 25 kGy gamma irradiation dose compared to other glasses.
Effect of Ultrasonic Amplitude on Surface Properties of Anodised Titanium for Biomedical Application
Authors: Lee Te Chuan , Mazlan Mohd Hafifi Hafizat , Abbas Mohamad Imran , Abdullah Hasan Zuhudi , Idris Maizlinda Izwana
Published: January 2016

Anodic oxidation is an electrochemical method for the production of ceramic films on a metallic substrate. It is a simple and low cost method to produce bioactive material. This work describes the effect of ultrasonic amplitude on the surface properties of anodised titanium. Specifically, high purity titanium foils were anodised in mixture of 0.04 M β-glycerophosphate disodium salt pentahydrate (β-GP) and 0.4 M calcium acetate monohydrate (CA) at 350 V and 70 mA.cm-2 for 10 minutes. The ultrasonic amplitude was varied from 20-60 μm. Next, field emission scanning electron microscopy (FESEM) glancing angle X-ray diffractometer (GAXRD) and atomic force microscopy (AFM) were used to characterise the anodised titanium. The results showed that application of sonication is able to remove the entrapped bubbles on the anode surface and enhance the oxidation process. The pores size and surface roughness were increased as increasing of ultrasonic amplitude. At ultrasonic amplitude ≥ 50 μm, rutile TiO2 was formed on the surface of oxide layer. It was found that the sonication is a simple method to improve the surface properties of anodised titanium for implant applications.
Effect of Fe2O3 Contents on the Ions Release from Phosphate-Based Glass
Authors: Muhamad Nor Mohd Al Amin , Mohamad Siti Hafizah
Published: January 2016

Currently, phosphate-based glasses have been extensively studied for their special characteristic of being soluble in aqueous medium and capable of releasing ions. This paper presents the relationship between the solubility properties and ion released of phosphate glasses having a composition of 6Al2O3-15K2O-14Na2O-(20-x)CaO-xFe2O3-45P2O5, where x = 2, 4, 6 and 8 wt.%. Clear and free bubbles of dark green glasses were obtained from the used of conventional melting technique at 1300 oC. The ion released and weight loss studies were determined from the immersion of the glass samples in deionised water for about 16 weeks under static condition. IR spectra revealed the formation of phosphate units such as metaphosphate and orthophosphate unit around 1097 cm-1 and 1107 cm-1 with the presence of Fe2O3 in the glass system. SEM image of the phosphate glass structure before and after immersion seems to be associated with the solubility of these glasses. From the study, the concentration of Na+ and K+ release decreased when more Fe2O3 contents were added to the system. Fe2O3 stabilize the network structure via the formation of P-O-Fe bond which more hydration resistant towards water penetrating molecules.
The Cutting Speed Influences on Tool Wear of ZTA Ceramic Cutting Tools and Surface Roughness of Work Material Stainless Steel 316L during High Speed Machining
Authors: Mohd Ali Afifah , Abdullah Norazharuddin Shah , Ratnam Manimaran , Ahmad Zainal Arifin
Published: January 2016

The purpose of this research is to find the effects of cutting speed on the performance of the ZTA ceramic cutting tool. Three types of ZTA tools used in this study which are ZTA-MgO(micro), ZTA-MgO(nano) and ZTA-MgO-CeO2. Each of them were fabricated by wet mixing the materials, then dried at 100°C before crushed into powder. The powder was pressed into rhombic shape and sintered at 1600°C at 4 hours soaking time to yield dense body. To study the effect of the cutting speed on fabricated tool, machining was performed on the stainless steel 316L at 1500 to 2000 rpm cutting speed. Surface roughness of workpiece was measured and the tool wears were analysed by using optical microscope and Matlab programming where two types of wear measured i.e. nose wear and crater wear. Result shows that by increasing the cutting speed, the nose wear and crater wear increased due to high abrasion. However, surface roughness decreased due to temperature rise causing easier chip formation leaving a good quality surface although the tool wear is increased.
Effect of NaNO3 as Enhancer on YBa2Cu4O8 Superconductor Phase Formation via Solid State Technique with Heating at Ordinary Oxygen Pressure
Authors: Cheong Choon Min , Ismail Nursyafiqah , Mohd Sarip Noor Azlina , Hamzah Noor Hakimah , Ruzman Nur Aleeya Ameera , Chen Soo Kien , Shaari Abdul Halim
Published: January 2016

YBa2Cu4O8 has emerged as better choice in superconducting application thank to it strong thermal stability. High pressure techniques had been employed for the preparation of YBa2Cu4O8 but it might costly and/or inconvenient. Several research groups had showed that the YBa2Cu4O8 can also be prepared by conventional solid state method with heating at 1 atm oxygen pressure; however the phase formation processes are yet brief and clear. This work infiltrated the phase formation processes in preparing the YBa2Cu4O8 under solid state method with heating at 1 atm oxygen pressure. The effectiveness of the use of sodium nitrate as an enhancer was brought to light by the experiment results. Significant YBa2Cu4O8 phases were successfully synthesized.
Synthesis and Characterization of Silica-Alumina Supported Ca and Ni Catalyst for Deoxygenation of Vegetable Oil into Diesel
Authors: Mijan Nurul Aiskin , Lee Hwei Voon , Alsultan Abdulkareem Ghassan , Taufiq-Yap Yun Hin
Published: January 2016

Developing an environmentally friendly and high-quality of fuel from vegetable oil (triglycerides) have attracted a great attention among the researches. Deoxygenation reaction using Ca-based catalyst is a potentially promising element for removing an oxygen species from organic compounds and converting the molecule to hydrocarbon. Addition of transition metal in the catalysis synthesis studies not only could enhance the properties of the catalyst but also could tune the selectivity toward desired product. Cooperation of mesoporous support such as silica alumina (SA) exhibit unique and excellent properties (high surface area, high porosity) which simultaneously could increase the catalyst activity. In the present studies, a set of bifunctional acid-base supported on the highly mesoporous SA doped with Ca and Ni were synthesized. The Ca (NO)3 and Ni (NO)3 were impregnated on the mesoporous SA support and were calcined at 500 °C for 2 h in order to activate the synthesized catalyst. The physicochemical properties of the catalyst were characterized by X-Ray fluorescence spectroscopy (XRF), X-Ray diffraction spectroscopy (XRD), temperature programme desorption carbon dioxide (TPD-CO2) and temperature programme desorption ammonia (TPD-NH3) and scanning electron microscopy (SEM).
Effect of Sintering Temperatures on Sr-Doped NiO Ceramics
Authors: Mohd Salim Nurul Nadia , Mohamed Julie Juliewatty , Ahmad Zainal Arifin
Published: January 2016

Sr - doped NiO ceramic was prepared using solid state method. The calcination temperature used at 950 oC for 4 hours and the sintering temperatures was varied from 1100 to 1300 oC for 3 hours. The results depict the microstructures increasing in grains size (1-8 μm) by increase of sintering temperatures. The density and porosity testing support the result of microstructures analysis. The larger grains size induced the increase in density and lower in porosity. The dielectric properties is observed in a wide frequency range of (1 - 1 000 MHz). The increase of dielectric constant is associated with the decrease of dielectric loss. The optimum sintering temperature was obtained at 1200 oC depict the grain size range (1 - 2 μm) with highest dielectric constant (1.61 x 103) and lowest dielectric loss (1.15) at 1MHz.