bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and Experimental Investigation on Tensile Properties of Natural-Sand Reinforced Polypropylene
Authors: Oumer Ahmed N. , Sahat Idris Mat , Nik Mu'tasim Muhammad Ammar , Kurniawan Tedi
Published: July 2015

Reinforced polymer composites are replacing metals in many engineering fields due to their high strength to weight ratio, low cost, and resistance to corrosion. In this study, the tensile properties of natural-sand particle reinforced polypropylene composites obtained by means of numerical method were compared with the experimental observations. Rectangular samples were prepared by heating the natural sand and polypropylene (PP) mixture at the melting temperature of PP and cooling in a rectangular mold. During cooling, pressure was applied on the upper part of the mold to avoid voids and shrinkages on the final sample. The concentration of the sand was varied as 5%, 10%, 15%, 20%, and 30% by weight. Then the samples were tested with 3-Point Bending and Universal Tensile Testing Machines to obtain the respective values of flexural and tensile properties of the composite samples. The numerical simulation was performed by using ANSYS software. For the simulation, structured mesh was constructed with 7500 elements and 36466 nodes. The experimental results indicated that the yield stress values dropped gradually from 21.62 MPa for 5% by weight to 8.01 MPa for 30% which leads to a conclusion that the higher the percentage of the sand particle reinforcement, the lower the tensile strength of the composite would be. Moreover, both the numerical and experimental results showed a linear increase in deflection with the increments of the applied load. These results are as expected and they confirm with the theoretical behavior of a bar subjected to axial loading. Hence, this study could assist in decisions regarding the design of reinforced composite products.
Tensile and Statistical Analysis of Sisal Fibers for Natural Fiber Composite Manufacture
Authors: Abir Md. Masudur R. , Kashif S.M. , Razzak Md. Abdur
Published: July 2015

To achieve sustainability in the composite industry, natural fibers must be able to replace synthetic fibers .In this work the tensile properties of sisal fibers were determined. The relationships between tensile strength, young modulus, failure to strain and gage length was studied. Also variation in tensile strength was quantified using statistical analysis. The relationship between Weibull statistics and gage length were also investigated. The strength of the sisal fiber obtained in this work was between 255-377 MPA and decreased with an increase in gage length. The Weibull modulus obtained was similar for all gage lengths and was around 2.5.
Achievement of Ductile Regime Machining in High Speed End Milling of Soda Lime Glass by Using Tungsten Carbide Tool Insert
Authors: Amin A.K.M. Nurul , Omar A.A. Che , Mohammed Kamal M.A. , Nassar Mahmoud M.A. , Mohd Zaib N.F. , Arif Muammer Din
Published: July 2015

Soda lime glass is widely used in optics, chemical apparatus, camera lens, micro gas turbines, light bulbs etc. on account of its high hardness, corrosion resistance, and excellent optical properties. These require high dimensional accuracy and flawless surface finish. However, soda lime glass is inherently brittle leading to subsurface crack propagation and fracture which compromise its functionality. To avoid these defects, the machining needs to be performed under ductile mode conditions. Therefore, this research investigates the viability and requisite conditions for achieving ductile regime machining (DRM) in high speed micro-end milling of soda lime glass. Machining was performed at high cutting speeds (30,000 to 50,000 rpm), feed rate (5 to 15 mm/min), and depth of cut (3 to 7 μm). A surface profilometer was then used to measure the surface roughness and a scanning electron microscope (SEM) used to scrutinize the resultant machined surfaces. The results demonstrate that ductile streaks and rounded gummy chips (without sharp or jagged edges) are produced in all runs. In addition, there are no subsurface cracks and the minimum surface roughness attained is 0.08μm. These indicate that DRM of soda lime glass is obtainable using high-speed micro end milling in a conventional end mill with tungsten carbide inserts.
Morphology of CNT-AL Nanocomposite under Different Ball Milling Parameters
Authors: Maleque M.A. , Abdullahi U. , Ali Mohammad Yeakub
Published: July 2015

The dispersion quality is the major concern in nanocomposite development as it determines the homogeneity of the enhanced mechanical and tribological properties of the composite. This work study the morphology of aluminium powder in the CNTs-Al nanocomposite prepared with different weight percentage of CNT in aluminium matrix using powder metallurgy route under high energy planetary ball milling operations at varying time and speed of milling of 2, 3hrs and 250, 300 rpm respectively. The preliminary mixing of CNTs and aluminium powder in a tube via manual shaking and the speed used could be the main contributing factor in achieving uniform dispersion of CNT in aluminium matrix within short time. Evidence of FESEM morphology with significant reduction of milling time confirmed that CNT was homogeneously dispersed and distributed into Al matrix.Key words: Milling parameter, CNT-Al nanocomposite, Homogenous dispersion
A Triangular Double Layer Microchannel Heat Sink: Effect of Parallel and Counter Flow
Authors: Manaf Hazli , Ahmed Shugata , Ahmed Mirghani I. , Hawlader M.N.A.
Published: July 2015

A numerical study is conducted by using ANSYS CFX 14.5, a commercial computational fluid dynamics program to predict the thermal performance of a counter and parallel flow on triangular double layered microchannel heat sink for various channel aspect ratios. Findings reveal that the counter flow configuration leads to a better heat transfer performance for low channel aspect ratio (α < 4) and higher Reynolds Number (Re > 700). For the parallel flow configuration, improved performance is normally shown when channel aspect ratio, α is more than 4 and lower Reynolds Number (Re < 700).
Design, Fabrication and Flight Testing of a Surveillance UAV
Authors: Idres Moumen , Makame Burhani , Ahmad Bala Nabil , Naji Saleh , Safiuddin Ahmad
Published: July 2015

Unmanned Aerial Vehicle (UAV) is becoming increasingly popular because it can perform variety of functions. These functions include surveillance, reconnaissance, monitoring, data collection and rescue operation. The purpose of this work is to design, fabricate and fly a low weight, low cost, small size UAV for a surveillance mission. The design is carried out based on Advanced Aircraft Analysis (AAA) software. The design process starts with the design specifications for a typical surveillance mission. Aircraft weight, wing loading and power loading were estimated in performance sizing process. Geometry was estimated using preliminary sizing. Aerodynamics of the aircraft was determined, which enabled the performance and stability to be analysed. If the desired performance is not achieved, the sizing is readjusted until a final design is reached. The aircraft was manufactured using foam, carbon rods, and fibreglass. The aircraft successfully flew at the first trial flight. This was followed by a successful flight with aerial photography.
Keywords: UAV, design process, fabrication process, composite structure, flight test
Evaluation of Orifice Flow Meter Accuracy under Pulsation Conditions
Authors: Abdullah Muhammad , Idres Moumen
Published: July 2015

Orifice meter is a flow measuring device which is widely used in various industrial applications. Although the device gives accurate measurement during steady flow, measurement errors related to square root and sampling errors are unavoidable if pulsations exist. This research investigatesand improves the performance of an orifice plate flow meter under pulsation effects. A simple model for the pulsating flow through an orifice meter is presented. Square root error (SRE) is estimated. Sampling errors (SE) are reduced by proper selection of the averaging time.
Mini-ATX Computer System in Vehicle
Authors: Sami Muhammad , Zeki Akram M.
Published: July 2015

The aim of this study is to create and assemble the system with customizing/building Linux kernel and environments to be compatible and efficient on mini-ITX computer. The objective of the study is to create/customizing lightweight operating system using GNU/Linux to be used on computer to be used on vehicle. The system would also optimize the size and functionalities most probably would be implemented on car computer system.Keywords: mini-ATX, CarPC, Linux, Ubuntu, Qt, QML
Performance Analysis of Heat Pipe Heat Exchanger for Solar Hybrid Desiccant Air-Conditioning System
Authors: Enggsa Zuraini Mohd , Rachman Arfidian , Nesti Lisa , Mat Sohif , Sopian Kamaruzzaman
Published: July 2015

This paper reports the development of a novel solar hybrid desiccant cooling system with heat pipe heat exchanger (HPHE). The aim is to achieve higher efficiency to reduce the use of electricity by utilizing the desiccant dehumidification system to remove latent load, while the vapour-compression and heat pipe heat exchanger meet the sensible load. Novelty comes as the heat pipe heat exchanger in the system operates efficiently without external power. Experimental set-up has been built by combining the rotary desiccant wheel, heat pipe heat exchanger with a compressive cooling system. Tests are carried out at typical operative ranges for air-conditioning applications, specifically for high hot and humid locations in Bangi, Malaysia. Acetone is used as refrigerant in the HPHE. Performance of HPHE are tested and proven to have direct impact on Coefficient of performance (COP). The results shows good performance of heat pipe heat exchanger efficiency with average efficiency and capacity of 0.65 and 2kw respectively. It is found that the hybrid system can achieve a higher energy performance in hot humid regions.
Remote Interior Temperature Control of Parked Vehicles
Authors: Latief Marsad , Ali Md. Azhar , Mannan Abdul , Saleh Tanveer , Bhuiyan Moinul , Raisuddin Khan Md.
Published: July 2015

Rise of interior temperature during daytime for a fully locked and parked car is a problem that needs to be addressed. The main reason for this significant rise in interior temperature is the heat that is trapped inside because of the closed glass window and greenhouse effect. This situation is very uncomfortable to get into the car that is exposed to sunlight for a prolonged period especially for toddlers and pets. Several measures have been proposed and some of them implemented to counter this issue. An example would be leaving the windows partially open when the car is parked to let air flow. More modern approach includes installing an external ventilation unit like a blower to regulate the internal temperature. However, none of these solutions are reliable and beneficent and moreover at times leave serious security loopholes apart from other typical drawbacks like power inefficiency and high cost. As such, there was an immense requirement to come up with a ‘smart and reliable’ solution for this issue keeping in mind factors like cost, power efficiency, user friendliness and reliability. A smart system was thus developed which gave a comprehensive control over the cooling system of the vehicle from a remote area. Moreover, other customizable necessary features like window control, safety and security has also been included. The device has been tested successfully on a Perudua Kalisa. Results obtained from the experiment shows interior temperature of the car can be brought to a comfortable range of 27-28o C within 15 minutes by implementing this device.
Two Degree of Freedom Plotter Using Robotic Arm
Authors: Bhuiyan Moinul , bin Hanafi Muhammad Muaz
Published: July 2015

This paper represents a two degree of freedom (DoF) robot arm as a plotter system. A pencil tool is used as the end effector of the robotic arm and experimented in drawing alphabets, for example ‘IIUM’. The control mechanism of the prototype is designed using Arduino controller. A user interface is also designed to send necessary commands to the hardware application board using serial communication cable. Through the experimentation, the movement of each joint of the robotic arm is presented in this paper. The result proves the feasibility of the system which could be improved in future research in drawing complex images.
Stress and Deformation Analysis of Aircraft's Fuel Tank under Different Inertia Load Cases in Addition to a Static Test Pressure Using FEA
Authors: Reddy D. Ramana , Aditya Nag M.V. , Gupta M.S.N.
Published: July 2015

In the modern era the aerospace technology plays a very significant role in the development of the mankind. The evolution of the light weight aircraft has a special focus in the present industrial trends. Several research organizations are in the process of developing Light Weight Aircraft, which is ideally suited for civil transport, aerial survey, training etc. This Light Weight Aircrafts are to be designed accordance to Federal Aviation Regulations part 23 (FAR-23). This paper deals with the analysis of the Aircraft's Fuel Tank under variable conditions. The analysis of aircraft fuel tank is carried out for different inertia load cases in addition to a test pressure of 3.5psi (24KPa), to validate whether the structure is safe or not. The size of the fuel tank has been taken as per the FAR-23 guidelines. The Finite Element Analysis is carried out to arrive at stresses and displacements in critical components using the Ansys software. The maximum shear stresses included are observed to be much less than the Yield strength of materials.
A Piezoelectric Based Energy Harvester with Magnetic Interactions: Modelling and Simulation
Authors: Ibrahima Dauda Sh. , Muthalif Asan G.A. , Saleh Tanveer
Published: July 2015

In recent years, utilizing kinetic energy in mechanical vibrations has become an interesting area of research. This is due to ubiquitous sources of vibration energy, coupled with the ever increasing demands to power wireless sensing electronics and Microelectromechanical (MEMs) devices with low energy requirements. Thus, researchers have ventured into developing different system configurations with the aim of harvesting vibration energy to power these devices. Cantilever beam systems with piezoelectric layer have been used as vibration energy scavengers due to their abilities of converting kinetic energy in vibrating bodies into electrical energy, whereas permanent magnets have been used to improve their performance. The only unresolved challenge is to develop energy harvesters that can produce optimum energy at a wider bandwidth. In this study, a mathematical model of a system of cantilever beams with piezoelectric layers having a magnetic coupled tip mass is proposed. The lumped parameter model of the harvester is developed to estimate the power output of the proposed harvester, and to visualise the effect of magnetic coupled tip mass in widening the frequency bandwidth of the energy harvester. Preliminary Simulation results using MATLAB have however shown the effectiveness of the proposed system.
Effects of Piezoelectric Actuation on Delamination in Transversely Loaded Composite Plates
Authors: Ghazali Nazwan , Dawood Mohamed Shaik , Kashif S.M.
Published: July 2015

Fiber reinforced composite materials are known to have poor tolerance to impact loads. Damages can be observed in the forms of matrix crack, fiber failure and delamination. In the case of low velocity impact, delamination is often a major concern due to its hidden nature. In this work, the effects of piezoelectric actuation on delamination in composite plates subjected to low velocity impact have been studied using LS-DYNA. It was found that, piezoelectric actuators can be used to reduce delamination in composite laminates. This was achieved by actuating the laminate to curve in the opposite direction of the incoming impact load.
LEADME: An Educational Software for Composite Laminate Analysis and Design
Authors: Ali J.S. Mohamed , Rubeya Abeid Abeid
Published: July 2015

LEADME
(
Laminate Analysis and Design Made Easy
), an educational software useful for the analysis and design of laminated composite structure has been developed. The software encompasses both the micro and macro mechanics analysis of lamina and laminate. The highlight of this software is that, apart from usual laminate analysis, the software is capable to solve practical laminate applications such as analysis of beams and also a design module is included. The software has been developed using MATLAB-Graphical User Interface (GUI) which makes it very user friendly. The results obtained from this software have been validated. It is expected that this software will serve as an educational tool complementing textbooks for students to gain better understanding of composite structural analysis.
A Case Study on Business Environmental Assessment in Malaysia and UK Metal and Fabrication SMEs
Authors: Sidek Atiah Abdullah , Abdullah Atikah , Backhouse Chris J.
Published: July 2015

In recent years, environmental issues are becoming more intense and widespread resulting in industries to consider adopting issues of sustainability and environment into their business operations. Small and medium sized enterprises (SMEs) are the backbone of Malaysia’s economy and have a significant cumulative impact on the environment [1]. Any framework or policy initiatives aimed towards fundamental and sustainable environmental improvements of local business practices will have to take this huge and important sector into account. This paper presents part of the findings of the study which investigate and compare the exclusive characteristics of Malaysia and United Kingdom (UK) SMEs and how these traits will lead to the adoption or rejection of green practices in the organisation.
Formulation of an IP-Based Model for Reactive Flow-Shop Scheduling Problem Subject to Arrival of New Orders
Authors: Abdesselam M. , Karim A.N. Mustafizul , Emrul Kays H.M. , Abdul Rahman Mohamed , Sarker R.A.
Published: July 2015

In order to survive in a competitive environment, industries are required to adopt strategies that ensure their abilities to provide their customers with a product featured by good quality, low cost and short delivery time. Short term scheduling plays a pivotal role in this context by ensuring the operations to be executed and monitored in an optimal or sub-optimal manner which guarantees the product shipping within the customers’ due dates at lower cost and/or higher utilization of resources. However, the dynamic nature of the shop floor environment causes the predictive schedules to be no longer optimal or even feasible. Frequent disruptions occurring during the execution of the predictive schedule require the operations managers to be reactive to make appropriate decision considering the new situation. Adequate research works based on integer programming are available in literature to cope with static scheduling problems, but there is a dearth in integer programming based approaches for dynamic or reactive situations. The aim of this work is to formulate a model that solves the reactive flow-shop scheduling problem subject to arrival of new orders. Objective function for makespan minimization and the comprehensive equations for predictive and reactive schedules are presented with the necessary elaboration.
Experimental Analysis of Cutter Engagement during High Speed End Milling of H13
Authors: Suprianto Mohammad Yuhan , Adesta Erry Yulian T. , Riza Muhammad
Published: July 2015

The aim of the present study is to investigate the influence of cutter engagement on cutting forces in end milling process of AISI H13 (48 HRc). The experiments were carried out on CNC vertical machining center. The machining conditions are as follows: Vc= 150, 200 and 250 m/min, fz= 0.05, 0.1 and 0.15 mm/tooth; a = 0.1, 0.15 and 0.2 mm for every cutting process. Central Composite Design with 20 runs was employed. Data analysis showed that cutter engagement influence the cutting force for the end milling process of hard material H13 in the same pattern to the similar experiment of different material. The present study of cutter engagement will be useful in tool path creation which is important for mold and die machining. The cutter engagement study related to cutting force in high speed end milling of AISI H13 has not yet been established. This study will help the NC programmers in choosing the suitable tool path that will give stable, productive, and more efficient milling process
Influence of Machining Parameters on Temperature when Drilling Carbon Fiber Reinforced Polymer (CFRP) Using Coated Diamond Drills
Authors: Konneh Mohamed , Iqbal Mohammad , bin Ani Hanfi , bin Yayah Mohd Zulhari
Published: July 2015

As the tendency towards weight reduction and low fuel consumption seems to drive the increased use of advanced exotic materials such as composites, titaniums and Inconels in the aerospace industry, the need for machining remains in aircraft industries as a post-processing operation. In the present work, the investigation of the influence of machining parameters on surface temperature when drilling CFRP using 4 mm-diameter 2-fluted carbide end-mill coated with diamond is presented. The temperature was examined on Thermal Gun Quicktemp 860-T1 sensor and analysed based on analysis of variance (ANOVA) of Central Composite Design of experiments and a first order mathematical model has been developed to predict temperature values for range of machining parameters used in the study. The relationship between the machining variables and output variables is established. It was found that the lowest temperature (32.2°C) was generated at rotational speed, 537 rpm and feed rate, 180 mm/min and at the highest temperature (39.1°C) generated at rotational speed, 4400 rpm and feed rate, 270 mm/min.
Preliminary Study: The Effect of Tool Engagement and Cutting Speed on Cutting Temperature during Contour Tool Path Strategy
Authors: Hamidon Roshaliza , Adesta Erry Y.T. , Riza Muhammad
Published: July 2015

In pocketing operation for mold and die, the variation of tool engagement angle causes variation in the cutting force and also cutting temperature. The objective of this study is to investigate the effect of tool engagement on cutting temperature when using the contour in tool path strategy for different cutting speeds. Cutting speeds of 150, 200 and 250m/min, feedrate from 0.05, 0.1, 0.15 mm/tooth and depths of cut of 0.1, 0.15 and 0.2 mm were applied for the cutting process. The result shows that by increasing cutting speed, the cutting temperature would rise. Varying the tool engagement also varied the cutting temperature. This can be seen clearly when the tool makes a 90oturn and along the corner region. Along the corner, the engagement angle varies accordingly with the radial depth of cut.
A Transparent and Tough β-Si3N4 Ceramic with a Whiskery Microstructure
Authors: Li Peng Xi , Wang Hong Qiang , Gui Liu Cheng , Li Jun , Zhang Hai Long , Jiang Guo Jian
Published: July 2015

The transparent β-Si3N4 ceramic with a whisker-like microstructure was prepared by hot-pressing at 2000 °C for 26 h, with MgSiN2 as an additive. The resultant material achieves the maximum transmittance of 70 % at the wavelength of about 2.5 μm and the transmittance value keeps higher than 60 % in the range of 700-4500 nm wavelength, which is attributed to the very small amount of the intergranular amorphous phase along with high density. The present transparent β-Si3N4 ceramic exhibits an indentation fracture toughness of 7.2±0.3 MPa m1/2.
The Formation of Alumina Ceramic Microspheres by Internal Gelation Process
Authors: Gao Yong , Ma Jing Tao , Zhao Xing Yu , Hao Shao Chang , Deng Chang Sheng
Published: July 2015

Alumina ceramic microspheres were prepared via internal gelation process. By dropping sol from a cold broth into hot silicone oil gelled microspheres would solidify within a few seconds by decomposition of hexamethylenetetramine (HMTA). The effect of the broth component on the performance of the broth and gelled microspheres obtained has been investigated. The Al2O3 ceramic microspheres can be obtained after aging, washing, drying and sintering. The Al2O3 microspheres prepared with optimized formulation have uniform size and good sphericity, with an average diameter of 690μm and crush strength of greater than 12N/sphere.
Preparation and Characterization of Al2O3-Based Composite Membranes by Sol-Gel Method
Authors: Liu Rui Ping , Su Wei Ming , Wang Chang An
Published: July 2015

Porous Al2O3-SiO2-ZrO2 ceramic composite membranes were fabricated by the sol-gel method. The effects of constitution of the composite sol, dip-coating parameters and calcination parameters on the morphology, phase composition, pore size distribution and BET surface area of the membranes were investigated extensively. The thermogravimetric analysis (TGA)/differential scanning calorimeters (TG/DSC), scanning Electron Microscopy (SEM), XRD analysis and N2 adsorption-desorption analysis was employed for the membranes characterization. TG/DSC curve shows that the suitable calcination temperature of Al2O3-SiO2-ZrO2 membranes is 1000°C. The SEM morphology displays a smooth and free-crack layer of Al2O3-SiO2-ZrO2 composite membranes on the surface of the support after calcination at 1000°C. Furthermore, the membranes were also successfully coated with a good adhesion to the support. The optimal composite membranes were obtained when the moral ratio of Al2O3-SiO2-ZrO2 was 10:2.3:1, the dip-coating parameters were four times dip-coating with every time of 60s respectively.
Contrast Investigation on Relative Translucency of Four Ultra-Transparent Dental Zirconia Materials after Veneered
Authors: Lu Rong Jian , Huang Yang , Yi Yuan Fu , Shao Long Quan , Wen Ning , Deng Bin
Published: July 2015

The purpose of this article is to contrast the relative translucency of four ultra-transparent dental zirconia materials after veneered, including Cercon zirconia, Zenostar zirconia, Lava zirconia and Upcera zirconia. All zirconia ceramics were prepared into samples of diameter 10mm and thickness 0.5±0.01mm.The relative translucency of samples were measured with color difference meter and statistically analyzed with SPSS 17.0.This experiment confirms that the existence of statistically significant differences in the relative translucency between different zirconia ceramics. According to the numerical level, the relative translucency of zirconia materials from high to low is Zenostar ZR Translucent>Lava Plus High Translucency zirconia> Cerconht full contour zirconia > Upcera zirconia. Zenostar ZR Translucent and Lava Plus High Translucency zirconia can be used to restore adjacent teeth that are higher translucent, while Cercon ht full contour zirconia and Upcera zirconia is better for molar teeth with poor relative translucency.
PEO Ceramic Coating on Mg-10%wt. Zn for Potential Biological Application
Authors: Hu Jonathan , Nie Xueyuan
Published: July 2015

Magnesium-zinc (Mg-Zn) alloys are strong candidates as medical implant materials due to their good biocompatibility and relatively high strengths. To manipulate the degradation of Mg-Zn alloy in the human body, a plasma electrolytic oxidation (PEO) treatment was applied to Mg-10%wt. Zn in this study because it produces a coating that is non-harmful to the human body and the process is inexpensive and environmentally friendly. Potentiodynamic polarization corrosion tests, performed in a simulated body fluid (Hanks’ Balanced Salt Solution) were applied to the coated and uncoated Mg-Zn samples. The results of the testing showed that the coated Mg-Zn exhibited higher corrosion resistance than the substrate. With the PEO coating thickness of 7.2 microns, the corrosion current density was reduced by 1.00 μA/cm2 from the uncoated Mg-Zn respectively, indicating a significant reduction in the degradation rate between pure Mg-Zn and coated Mg-Zn from 7.0 to 3.7 kg/year. A pin-on-disc tribometer was employed to measure the coefficient of friction (COF) for the coated and uncoated Mg-Zn samples, lubricated with and without Hanks’ solution. The measured COF of the coated sample was very low (averaging to be about 0.22 under the lubricated condition) and comparable to that of the substrate which exhibited an averaged COF of 0.13 under the lubricated condition.
Effects of Zr/Ti Ratio on the Electric-Induced Light Scattering Performances of PLZT Transparent Ceramics
Authors: Xia Bin , He Xi Yun , Zeng Xia , Qiu Ping Sun , Cheng Wen Xiu
Published: July 2015

Lead lanthanum zirconate titanate (PLZT) transparent ceramics have attracted more and more attentions for their unique electric-induced light scattering effects. The PLZT ceramics of 7.45 mole% lanthanum with different Zr/Ti ratios (Zr/Ti=68/32, 69/31, 70/30, 71/29, 72/28) were prepared by the hot-press sintering method. The X-ray diffraction patterns confirm that all the PLZT samples are perovskite structure without detected secondary phases. The SEM images of the fracture surfaces of the samples show that all the PLZT materials tend to fracture transgranularly, and exhibit fully dense and uniform microstructures. All the samples with different Zr/Ti ratios present typical relaxation ferroelectric phase transition characteristics with square shaped hysteresis loops. Noticeably, all the original PLZT samples show an excellent transparency in the wavelength range from visible to near-infrared, and they will become opaque after an appropriate electric field experienced. The opaque sample can also recover to the transparent state when an inverse compatible electric field acts on it. The contrast ratio of the sample increases firstly and then decreases when the Zr/Ti ratio increases from 68/32 to 72/28 (λ=632.8nm). The PLZT (7.45/70/30) material shows a maximum contrast ratio, which makes it promising to apply in optical modulators.
Effect of Sintering Temperature on Structure and Electric Properties of (Ba0.96Ca0.04)(Zr0.05Ti0.95)O3 Ceramics
Authors: Guan Xin , Deng Xiang Yun , Hao Jian , Sun Guang Hao , Huang Chuang Jun
Published: July 2015

Barium calcium titanate (Ba0.96Ca0.04)(Zr0.05Ti0.95)O3 ferroelectric ceramics were prepared by sol–gel technique. The ceramics were sintering at 1290°C-1370°C. X-ray diffraction was employed to investigate the microstructure, and the surface topography was investigated by SEM graphs. The dielectric constant vs temperature was measured by Temperature dielectric spectrometer, and TF Analyzer 2000 measured the ferroelectric properties. It can be found that all the ceramics show pure perovskite structure suggesting that solid solution were formed. SEM showed that the samples uniform in grain size at 1330 °C. Our study revealed that when the sintering temperature is 1330 °C the maximum dielectric constant was 29,600, the maximum piezoelectric coefficient d33 could reach 399pm/V and the remanent polarization (Pr) was 8.3 μc/cm2, respectively.
Characterizations of (Mn, Sb) Co-Tuned PZMNS-PZT Piezoelectric Ceramics in the Morphotropic Phase Boundary and their Applications on Multi-Bulk Step-Down Piezoelectric Transformers
Authors: Tsai Cheng Che , Hsieh Hsiang Ho , Chu Sheng Yuan , Chen Zong You , Huang S.K.
Published: July 2015

In this study, the (Mn, Sb) co-tuned PbCa0.01[(MnxZn0.1-x)1/3(SbxNb0.1-x)2/3 (Zr0.505Ti0.4895)0.9]O3 (PCZMNSZT-100x) ceramics were prepared near the morphotropic phase boundary (MPB) using the wolframite precursor method. The phase structure evolutions, electrical and temperature stability properties were systematically investigated. As the fraction of rhombohedral phase increases, the degree of disorder in the diffused phase transition (DPT) correspondingly increased and the “hard” piezoelectric characterization would be enhanced. Moreover, the temperature change rate of k, Qm and fr can be tuned by adjusting the x content. The specimens with x=0.08 exhibit the obtained values as kp ~ 0.50, kt ~ 0.52, Qm ~ 1550, and the low temperature change rate of properties having Δfr/fr = -0.02% and ΔQm/Qm = 10.5%, up to 100 °C. To evaluate the material feasibility, the proposed multi-bulk step-down transformers using a ring/dot structure are fabricated. Their obtained electrical properties have a maximum efficiency of 92% with an output power of 15 W, a voltage gain of 0.68 and a nearly zero temperature change rate of resonant frequency are found at the load of 100 Ω.
Li2ZnTi3O8 Microwave Dielectric Ceramics Prepared by the Reaction-Sintering Process
Authors: Hu Xu Sheng , Yao Guo Guang , Tian Xiu Lao
Published: July 2015

Li2ZnTi3O8 ceramics were prepared by reaction-sintering process (calcination free). The crystal phase and microstructure were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). A pure phase of Li2ZnTi3O8 ceramics sintered at 1075 °C-1150 °C with cubic spinel structure was confirmed by XRD. The microwave dielectric properties (εr, Qxf) of Li2ZnTi3O8 ceramics were strongly dependent on the densification and grain size. The τf of Li2ZnTi3O8 ceramics was almost independent with the sintering temperatures. In particular, Li2ZnTi3O8 ceramics by reaction-sintering method sintered at 1125 °C for 5 h exhibited good combination microwave dielectric properties of εr=21.7, Q×f=70 500 GHz (at 7.5 GHz) and τf=-13 ppm/°C.
Leakage Current Characterization of BaTi2O5 Nanowires
Authors: Deng Zhao , Dai Ying , Xiao Hua , Pei Xin Mei
Published: July 2015

Single-crystalline BaTi2O5 nanowires were synthesized by a simple molten salt method, using BaC2O4•H2O and TiO2 powders as precursors. Electrical characterization was conducted with the as-synthesized BaTi2O5 nanowires. The current-time data of the nanowires obeyed the Curie-von Schweidler law. Steady-state I-V curve was obtained at room temperature from current-time data and it revealed that the leakage current of BaTi2O5 nanowires obeyed the ohmic law under low voltage, and obeyed the space-charge limited current (SCLC) law under higher voltage. The conductivity value of the BaTi2O5 nanowires is 2*10-6 S/cm.
Luminescent Properties of Polycrystalline Cerium-Doped Lutetium Pyrosilicate Powders
Authors: Fan Ling Cong , Zhang Xiao Xin , Zhang Yu Yu , Shi Ying , Xie Jian Jun , Lei Fang
Published: July 2015

Single phase LPS powders with nanosize particles were synthesized by a sol-gel process. Temperature and calcination temperature dependence of luminescence of the synthetic LPS:Ce powders were investigated under vacuum ultraviolet (VUV)-UV excitation. Luminescence intensity of LPS:Ce powders increase with calcination temperature, but it reaches the maximum at 1250 °C. Decay time of the LPS:Ce powders also slightly increasing from 27.1 to 30.5 ns as calcining temperature elevating. Both of them attribute to improved crystallization of LPS:Ce powders. Total luminescence intensity of LPS:Ce powder calcined at 1350 °C for 2 h has no noteworthy variation as the temperature rising in temperature 30-260 K range, this luminescence stability suggests that LPS:Ce would also be a good scintillator for high energy radiation detection in low temperature condition with temperature variation.
Effect of Technological Conditions on (Na0.4Li0.6)CrSi2O6 Emerald Green Ceramic Pigments
Authors: Chen Yun Xia , Chen Jing , Su Xiao Li , Nie Ting , Wang Jin
Published: July 2015

Green pigments have been synthesized. Sodium silicate, chromium oxide, lithium carbonate and quartz were used as the main raw materials to prepare (Na0.4Li0.6)CrSi2O6 emerald green pigments by solid state reaction under the non-reductive conditions. The effects of the various technological conditions, such as raw materials ratios of (Na0.4Li0.6)/Cr/Si, calcination temperature, holding time and the type of mineralizers, on the color presentation of the synthesized pigments were studied. XRD and SEM were employed to analyze the crystalline and structure of the synthesized pigments. Chroma value was used to characterize the color of the pigments. The results show that the optimized (Na0.4Li0.6)CrSi2O6 pigments with chroma value of L*=57.78, a*=-18.98~-18.68 and b* = 10.88~9.01 were obtained.
Effect of Y2O3 on Microstructure and Properties of cBN/SiAlON Composite
Authors: Shi Xiao Fei , Cai Zhi Xin , He Chao , Wang Jian Jun , Yue Xin Yan , Ru Hong Qiang
Published: July 2015

cBN/SiAlON composites were prepared by spark plasma sintering (SPS) method using Si3N4, AlN, Al2O3,cBN and Y2O3 powders as raw materials. The sintering process is at the temperature of 1500°C holding for 5 min. Effect of the Y2O3 content on phase composition, microstructure, bulk density, hardness and fracture toughness of the cBN/SiAlON composite was investigated. The experimental results showed that when the Y2O3 content was 0.2 wt. % the bulk density and fracture toughness of the composite had the maximum values of 3.0 g/cm3 and KIC = 5.7 MPa∙m1/2, respectively. The cBN/SiAlON composite with 0.8 wt. % Y2O3 addition got the maximum hardness of 16.4 GPa.
Particle Size and Chroma Control of CoAl2O4 Pigment
Authors: Chang Qi Bing , Wang Xia , Wang Yong Qing , Zhou Jian Er , Zhang Xiao Zhen
Published: July 2015

To meet the requirement of ceramic pigment for ink jet printing, CoAl2O4 pigment was prepared by nitrate-glycine method. The effect of nitrate/glycine ratio, calcination temperature and organic sacrificial agent on the particle size and chroma of the blue pigment were considered. The results show that the particle size of the pigment increases with the increase of glycine in the ratio and the decrease of the calcination temperature. However, the increase of the calcination temperature results in the broadening of the particle size distribution of the pigment. The addition of the organic sacrificial agent contributes to decrease the particle size of the pigment, which is about 2.0 μm. The chroma of the pigment is L*=47.62、a*=9.49、b*=-51.41. The blue pigment can be used in ink jet printing.
Effects of Ni Sheath on the Microstructure and Properties of BSCCO-2223 Tapes
Authors: Li Xiao Guang , Chen Xing Pin , Zheng Xuan , Liu Meng , Sun Hong Fu
Published: July 2015

Effects of Ni sheath on the microstructure, mechanical properties and bubbling phenomenon during heating process of BSCCO-2223 ceramic tapes have been investigated. Ni sheath gives Bi-2223 tapes a better ability to protect ceramic core from the damage of external force. Hardness of Ni sheath is double than that of Ag sheath reached to about 70 HV. Tensile strength of the Ni-sheathed Bi-2223 tapes is also enhanced by 80%. Harder Ni sheath is also beneficial to improve the texture of the tapes. However, serious bubbling phenomenon, which can reduce the transport property of tapes, will appear during heating process owing to the bad oxygen permeability of Ni. A lower heating rate (30°C/h) is a favorite to decrease the number and size of bubbles. In addition, Ni sheath can reduce the formation rate of Bi-2223 phase which implies that longer sintering time and higher cost of fabrication will be consumed.
Synthesis of Nb2AlC Material by High Temperature Solid State Reaction Method
Authors: Wang Yu Chen , Liang Zhen Hua , Peng Gui Hua , Xu Jian Guang
Published: July 2015

The Nb2AlC powders were synthesized by high temperature solid state reaction method ,in which, the mixed powders of niobium (Nb), aluminum (Al) , graphite (C) were used as raw materials in an atomic ratio of 2.0:1.1:1.0, respectively. And the heating temperature was adjusted in a range of 1600–1650°C in order to investigate the effects of different preparing conditions on the synthesis of Nb2AlC .The phase composition and morphology of the products were analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) respectively. The results indicated that all the XRD peaks can be indexed as Nb2AlC with improved crystallization at 1610°C.And the SEM photographs show that the products are layered morphology.The reaction mechanism of Nb2AlC synthesis was also studied.
Effects of Processing Condition on the Properties of Porcelain Building Ceramic Tiles
Authors: Dong Wei Xia , Zhou Jian Er , Gu Xing Yong , Bao Qi Fu , Liu Kun , Zhao Tian Gui
Published: July 2015

Due to low water absorption, high bending strength and abrasion resistance, and excellent chemical and frost resistance, porcelain building ceramic tiles are the highest increase in production and sales over all other kind of building ceramic tiles materials. In this paper, porcelain building ceramic tiles was prepared by a fast firing process of rare earth tailings as the main raw material, low fused sand and Zhuji porcelain sand et al mixture. Effects of firing temperature and forming pressure on the sintering behavior and mechanical property of porcelain building ceramic tiles were studied. The sintering behavior of the fired samples was evaluated by linear shrinkage and water absorption. The fired samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and bending strength measurements. The sample is pressured at 15 MPa and sintered at 1180 °C and endowed with 0.04% of the water absorption and 51 MPa of the bending strength, due to denser microstructure. The obtained results would contribute to save natural resources and protect environment.
The Use of Correlation and Frequency Analysis for Detection of Deformation in 7050 Aluminum Beams
Authors: Liao Fei Yi , Li Shi Jun , Lin Yuan
Published: July 2015

Lead zirconate titanate (PZT) is one of the most widely used ferroelectric and piezoelectric materials. Its piezoelectricity is widely used in the applications of structural health monitoring (SHM). Here, we use PZT ceramics as sensors to detect the deformation of structure using guided Lamb waves. In order to well analyze the multi-modes of Lamb waves and achieve detection of deformation in superposed wave peaks, correlation and Fourier transform were used to extract peaks in both time and frequency domain. In this paper, a 7050 aluminum beam and three-point bending test machine were utilized to test the changes of waves when different deformations were introduced. With the adjustment of correlation index, change of time delay and new peaks occurring in time domain demonstrated the change of deformations. In frequency domain, the change of central frequencies and magnitudes also demonstrated the change of deformations. The study shows the potential applications of PZT sensors in detection of deformation.
Preparation and Thermal Properties of Pressureless Sintered AIN/SiC Composites
Authors: Ai Shu He , Zhang Yu Jun , Gong Hong Yu , Li Qi Song
Published: July 2015

AlN/SiC composites with 5 wt.% Y2O3 addition were fabricated by pressureless sintering at 1700-1950 oC. The influences of sintering temperature and SiC content on the relative density, mechanical property and thermal conductivity were studied. With sintering temperature increasing from 1700 oC to 1750 oC, the relative density increased significantly to about 98.0%, without evident changes from 1750 oC to 1900 oC, and then decreased slightly at 1950 oC. As SiC content increased, the flexural strength of composites sintered at 1750 oC increased firstly, and then decreased, obtaining a maximum flexural strength of 337 MPa at 20 wt.% SiC content. Meanwhile, the thermal conductivity decreased from 60 W/(m∙K) to 40 W/(m∙K) with SiC content increasing from 0 wt.% to 30 wt.%. Moreover, in the sintering temperature range from 1750 oC to 1950 oC, the thermal conductivity increased from 45 W/(m∙K) to 55 W/(m∙K) for AlN-10 wt.% SiC composites, but decreased from 40 W/(m∙K) to 36 W/(m∙K) for AlN-30 wt.% SiC composites.
Characterization of Metal-Like Carbides-Graphene Composite Prepared by SPS Method
Authors: Wyzga Piotr , Jaworska Lucyna , Putyra Piotr , Podsiadlo Marcin , Cyboron Jolanta
Published: July 2015

High hardness, good thermal and electrical conductivity make carbides technologically important materials. The high melting temperature and low coefficients of self-diffusion make it difficult to obtain full dense material. In this paper the results of Spark Plasma Sintering (SPS) of transition metal carbides: NbC, TaC, TiC, ZrC, VC with the addition of graphene 10-20 nm x 14 microns in an amount of 2.5 mass % are presented. Powders were mixed in isopropyl alcohol in a planetary ball mill for 1h. The sintering processes was carried out at 2200°C at two different times: 5 and 30 min. Microstructure of the samples was analyzed using scanning electron microscopy. The measurements of density, Young's modulus hardness and electrical properties were carried out, also. The best properties were obtained for titanium carbide powder, sintered for 30 min. The most significant density increase of the sintered carbide–graphene composite by about 5.3% (depending on increasing sintering duration) was obtained for niobium carbide, while the smallest densities change for zirconium carbide.
Study on Thermal Shock Resistance of Alumina Composite Ceramics by Indention Quenching Method
Authors: Qian Fen Ling , He Zhi Yong , Xie Zhi Peng , Wang Xiao Bo , Zhang Qi Fu
Published: July 2015

Alumina ceramics are the most widely used structural ceramics, especially in aviation, spaceflight and war industry area. However, alumina is of covalent bond, with low fracture toughness and poor thermal shock resistance, which baffle the application of the alumina ceramics in engineering. In this paper, mullite fiber was used to improve its toughness and thermal shock resistance. Alumina-mullite composite ceramics were prepared by hot press sintering. The effect of mullite fiber on thermal shock resistance of ceramics was investigated through indention quenching method. Meanwhile, the mechanism of its reinforcing and toughening and the relationship between mechanical properties and addition of mullite fiber were also discussed.
Bokolo v S 2014 (1)sacr 66 (sca): The practicality of challenging dna evidence in court
Authors: Lubaale Emma Charlene
Published: July 2015

The techniques used in DNA profiling are well established and scientifically validated. The scientific validity of DNA evidence can, however, be so persuasive that such evidence risks being reduced to proof of guilt or innocence. Thus, the incorrect use of DNA evidence could lead to a miscarriage of justice where the innocent are convicted and the guilty are acquitted. Drawing from the Supreme Court of Appeal decision in Bokolo v S (Bokolo case), this case note discusses how DNA evidence can be placed in its proper forensic context. The article sets out the ideal role of expert witnesses, the role of opposing or neutral experts, and the active role of judicial officers in evaluating DNA evidence.
Intelligence-led policing: A proactive approach to combating corruption
Authors: Budhram Trevor
Published: July 2015

Corruption causes substantial social and economic harm. The South African government’s attempts to combat corruption have relied on strengthening legislation, introducing statutory investigative bodies, initiating public anti-corruption campaigns, and appealing to the integrity of individuals. Yet corruption remains a big problem in South Africa. However, one approach that has yet to be pursued is intelligence-led policing (ILP). ILP is a model built around proactive risk assessment and risk management. This article explains how ILP can be used to investigate corruption in South Africa.