Materials Engineering Symposium on Innovation for Industry

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item: Conference-Abstract
Activated graphene oxide for removal of methylene blue from wastewater
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Raveena, LAL; Viraji, HA; Rathnayake, RMSL; Sitinamaluwa, HS; Sivahar, V
Lately, activated oxidized graphene has sparked a lot of attention in the fields of wastewater treatment and water filtration. Here, the possibility for using activated graphene oxide (AGO) to remove methylene blue (MB) from water systems was investigated. Commercially available Graphene Oxide (GO) was obtained, and it was further modified by alkali-activation method to obtain AGO. The resulting AGO was tested as an adsorbent for methylene blue removal. Activation time was varied to optimize the MB removal of the adsorbent and then the adsorbents were characterized by using FTIR, SEM, BET and XRD analysis. Synthesized AGO shows prominent MB adsorption characteristics due to H-bonding, and electrostatic interactions. To evaluate the adsorption capacity, batch adsorption experiments were carried out and the effect of pH and temperature on dye adsorption were investigated. Maximum adsorption capacity of 123.47 mg/g was obtained for AGO sample which was activated for 1.0h and the data were well fitted to Langmuir isotherm model. These findings demonstrate the possibility for cationic dye removal from wastewater systems using an economically viable AGO.
item: Conference-Abstract
Characterization of creep behaviour of viscoelastic materials by ultrasound pulse- echo technique
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) HEWESSAGE, HDDN; KOTHALAWALA, SSW; Sivahar, V; Abeygunawardana, AAGA
For any viscoelastic material, creep is a phenomenon which tends to change microstructure and the mechanical properties of material. Therefore, it is important to quantify and predict the creep and creep rate of a component. In this investigation, several samples of LDPE were used to measure the creep and both ultrasonic attenuation and velocity measurements using a 5 MHz transducer were employed for characterizing the samples. Our findings indicate that velocity and attenuation measurements can be used to characterize and quantify creep and creep rate of viscoelastic materials.
item: Conference-Abstract
Design and development of ultrasonic wave generator using piezoelectric ceramics
(Department of Materials Science and Engineering, 2020-02) Sivanujan, S; Adikary, SU; Abeygunawardane, AAGA
Ultrasonic transducers using piezoelectric materials are popular among researchers because of the efficiency, ease handling, low weight, and small size. In this research, an ultrasonic wave generator using piezoelectric ceramics was designed using mathematical modelling and finite element analysis. Then a prototype was fabricated to compare the performance. Piezoelectric constitutive equation for converse effect and differential equation of spring- mass system with a forcing function were used for mathematical calculation in thickness mode to determine resonant frequency, dimensions of the design and acoustic impedance of matching layer and backing layer. The matching layer transmits the mechanical vibration as ultrasonic wave. To identify optimum parameters of the design, finite element analysis was done. The design resonant frequency and parameters of layers were calculated from solid mechanics and electrostatics for Eigen frequency and Frequency domain studies using 3D model. Transmitting wave frequency in water and air was calculated from acoustic pressure variation, which was obtained as a results of simulation using 2D axisymmetric model. Arduino software was used to feed controlled electric signals to piezoelectric material. Finally a prototype device was developed using Lead Zirconate Titanate (d33 = 400 ×10-12 m/V) as piezoelectric ceramics, Aluminum as matching material and Steel as backing material. Thickness of them are respectively 1.5 mm, 3 mm, and 10 mm. Terminal wires were soldered and all three were merged together using glue gun with polymer binder. Prototype testing was performed with Oscilloscope. The resonance was observed at 75 kHz, 182 kHz, and 232 kHz. Resonance was also confirmed by Impedance - Frequency and Phase - Frequency analysis using LCR measurements.
item: Conference-Abstract
Design and fabrication of split Hopkinson pressure bar apparatus to investigate high strain rate mechanical behavior of low carbon steel
(Department of materials Science and Engineering, University of Moratuwa., 2021-12) Edirisinghe, DJ; Nidushan, ND; Abeygunawardana, AAGA; Abeygunawardana, AAGA
This work consists of designing and fabricating of compression split Hopkinson pressure bar (SHPB) apparatus to investigate the high strain rate stress-strain behavior of low carbon steel at strain rates of 217.686 s-1, 283.728 s-1, and 356.692 s-1. High strain rate mechanical behavior at the aforementioned regime has never been studied in Sri Lanka; notably with SHPB apparatus. High strain rate behavior of materials is essential in designing mechanical components to be used in high loading impact components such as sports equipment, automotive applications and ballistic applications. General mechanical behavior analogies used for quasi static regime such as universal tensile testing machine are inaccurate and inadequate in dealing with high strain rate related studies. A test bench, loading device, an incident bar, a transmission bar, bar holders, a momentum trap, and standard specimens were fabricated. Two data acquisition and recording systems were used for collecting data from the incident bar and the transmission bar with a maximum sampling rate of 428571 Hz. The data acquisition and recording system components were strain gauges, a Wheatstone bridge circuit, an amplifier, a microcontroller, a power supply, a USB hub, and a USB to micro-B cable and computer. Software codes were developed to collect the data and process the experimental data and determine the corresponding flow curves. In further work on this area, it was recognized to use much more accurate strain gauges suitable for the high strain rate applications so that the data will be more accurate and efficient.
item: Conference-Abstract
Design and optimization of linear actuator for biomedical applications
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Chandrasiri, WAD; Rashmika, WAD; Adikary, SU; Abeygunawardana, AAGA
Microelectromechanical system (MEMS) actuators are a promising innovation that is essential to the development of a wide variety of biomedical devices. The invention of smaller fluid pumps has been valued with increasing interest, these miniaturized micro pumps are designed to handle a very small, precise, and controllable amount of fluid normally in the range of μl/min to ml/min. Thyroid hormone imbalance is a highly increasing, common, genetically or non-genetically disease, which is conducted to Hypothyroidism (an underactive thyroid gland) and Myxedema Coma. So, levothyroxine should be injected frequently into the human body to maintain the metabolic system. This research was carried out to design a linear actuator for a micro pump that injects a certain dose of levothyroxine hormone into the human body accurately. Lead Zirconate Titanate (PZT) gives a high piezoelectric charge coefficient value with high frequency and stiffness that is required for the micro pump. Theoretical mathematical calculations of the piezoelectric stack configuration were carried out to get the displacement of the actuator and maximum displacement. Considering water as the fluid, an equation for flow rate was derived theoretically with supposing fluid behave as a laminar flow. Finite Element Analysis (FEA) was performed to identify the suitable dimensions of the micro pump which is compatible with the flow rate of the fluid.
item: Conference-Abstract
Design and simulation of solid state micropump based on piezoelectric actuator
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Sivahar, V
This research presents the design and simulation of a solid-state insulin micropump based on a piezoelectric actuator for a wearable insulin pump device to be used on the human body. The primary objectives of this design are to minimize the need for frequent dosing, replace oral therapy, and alleviate the discomfort associated with painful injections for individuals with diabetes. Our research provides an overview of key concepts, the operating principle, and the design considerations of the micropump. The selection of materials, theoretical studies, and the optimization process of the pump were also investigated in our research. Finite element analysis was employed to optimize the design, and the simulations were conducted using COMSOL Multiphysics 5.3a software in the research. By utilizing the piezoelectric actuator, the proposed micropump demonstrates promising potential for reasonable insulin delivery. The simulations enable the evaluation of various parameters such as actuator performance, fluid flow dynamics, and overall flowrate. The results obtained from the simulations provided valuable insights into the overall performance of the pump and aid in its refinement. The integration of wearable insulin pump devices with this micropump design opens new possibilities for convenient and effective diabetes management.
item: Conference-Abstract
Design of a Dynamic Mechanical Analyser for Rubber Compounds
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Herath, HMRC; Rodrigo, IJ; Weragoda, VSC; Sivahar, V
Dynamic mechanical analysis (DMA) is a powerful technique for characterization of the viscoelastic properties of polymers such as thermoplastics, composites, thermosets and elastomers in the form of sheet specimens, films, fibers, coatings or adhesives. DMA instruments measure the modulus (stiffness) and damping (energy dissipation) properties of materials as they are deformed under dynamic stress. When a polymeric material is subjected to a cyclic sinusoidal stress within the viscoelastic region, the corresponding strain in the material would be out of phase due to the delayed response of the viscous portion of the material. This phase difference corresponds to the frequency of the force application and this is a unique characteristic of the polymer material. Amplitude of the strain curve and phase shift between stress and strain curves are usually identified as basic parameters. In this design which is based on the ISO 6725 standard, forced vibration method was used and the vibrations are impacted by the inertia force of an eccentric rotating mass is used to generate sinusoidal force. Multi stress and multi frequency modes are operated by adjusting eccentricity and speed of rotating mass. The instrument also has facility to adjust the static force imparted on the specimen. Deformation of the material is detected by a displacement sensor. This design satisfied all requirements of the testing standard.
item: Conference-Abstract
Design of natural fiber and wastepaper composite using numerical analysis method
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Madushani, RK; Dilhari, BA; Udayakumara, SV; Abeygunawardana, AAGA
The consumption of papers in various applications has been increased rapidly during the past decades. To produce one ton of paper; 12 trees, 540 000 liters of water, fuel consumption for transporting the trees are used whereas 10 liters of water is needed to make one A4 paper. Thus, during paper production natural resources are enormously utilized as well as many chemicals are involved in the process. Therefore, this study was conducted to design a wastepaper-based composite with natural fiber as reinforcement. Jute, coir, silk, and wool fibers selected as reinforcement and the study was carried out using simulation in SOLIDWORKS software. Among the selected fibers jute fibers showed better properties and therefore it was selected for composites simulations. Firstly, volume fraction was calculated, and the critical volume fraction was determined. Critical fiber volume fraction was nearly 0.23. Then the fiber volume fraction was optimized using COMSOL Multiphysics software. The periodicity boundary condition and rule of mixture techniques were used to compare and obtained the most suitable fiber volume fraction. The optimized fiber volume fraction was 0.4. Thereafter the micromechanics analysis of a unit cell was carried out with the most suitable fiber volume fraction. The elasticity matrix was obtained for the material. Finally, the stress analysis of the composite was done by applying a 100N load on the composite, which was fixed from four edges. The longitudinal elastic modulus obtained was 8.0726GPa with a thickness of 0.4mm and a Grammage of 488.92 gm-2. Thus, a natural fiber composite with wastepaper can be produced with most suitable fiber volume fraction of 0.4 with numerical analysis methods.
item: Conference-Abstract
Design/fabrication of bi-axial tensile testing machine and numerical modeling of polymer composite under bi-axial stress state
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Arachchi, KADDK; Sandanayaka, SMP; Abeygunawardane, AAGA; Weragoda, VSC; Abeygunawardana, AAGA
In real engineering applications, materials are subjected to different types of loads applied in several directions. Characterizing materials using the Uni-axial tensile testing can be only enough for Isotropic materials. But it is not accurate when testing the Anisotropic materials where the properties vary with different crystallographic orientations. The main scope of this research is to Design & Fabricate the Sri Lankan first ever Bi-Axial Tensile Testing Machine to Characterize Polymer Composites. This study enabled to fabricate a full-scale Bi-Axial Tensile Testing machine for the first time in Sri Lanka. The machine uses four linear actuators which allow cruciform specimen subjected to load from two independent directions. A non contact strain measurement technique using digital Image correlation has been used to measure the strain induced in the specimen. MCalibration – an optimization numerical tool was used to calibrate the best fit material model for the particular application under the biaxial stress state, and a commercial FEA software ABAQUS was used to build and analyze the tested material for its anisotropic nature.
item: Conference-Abstract
Designing an elastomer for reinforced elastomeric cushion bridge expansion joints
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Welivita, WKCS; Wijayasiri, ISWC; Weragoda, VSC; Abeygunawardana, AAGA
This project is focused to improve the properties and to avoid the premature failures of the Reinforced Elastomeric Cushion Bridge Expansion Joint which is used by the industrial organization of Expressway Operation, Maintenance and Management Division of Road Development Authority in Sri Lanka. During the project, COMSOL Multiphysics software was used to analyze the stresses of the expansion joint. Rubber compounds were mixed in a two-roll mill according to a predetermined formulation and were vulcanized using a compression molding machine. Tensile strength, hardness, abrasion resistance, aging resistance (ozone aging and hot air oven aging) were measured according to the standards.
item: Conference-Abstract
Designing of rubber based strain sensor as a vehicle tyre performance indicator
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Vinoshan, S; Kobika, B; Weragoda, VSC; Abeygunawardana, AAGA
For the development of strain sensor to measure the uneven deformation in the vehicle tyres, so that to improve the safety of the vehicles and self- driving cars. the design of elastomeric strain sensor fulfils the requirement of tyre properties change during application. Rubber strain sensor works like piezoresistive material because electric properties change while change the strain of the subject. Therefore, elastomeric strain sensor composition with rubber composites based on natural rubber and electric conductive filler such as carbon black and carbon nanotube have been studied and used for work like as piezoresistive. Develop the strain sensor as its performance does not lose while dynamic load application. The carbon black filler network composition changes during applied load. The rearrangement of the filler network happens while realizing the load. Considering crosslink density and stiffness that affect the performance of sensor composition was selected because lower crosslink density make mobility of filler network so is improve the electric properties. Suggestion on develop a circuit for detect the senor resistance variation and mount in the vehicle tyre was done. The analysis data transfer to the vehicle electronic system for identify what are issues such as road condition, improper tyre pressure, tyre vibration level and steering angle. Then according to the information vehicles can make warning to the diver and make safety improvement.
item: Conference-Abstract
Determination of moisture content of wood using ultrasonic pulse velocity
(Department of Materials Science and Engineering, 2019-01) Vithanage, VSC; Wijesinghe, MPMC; Piyathilake, SAKVM; Sivahar, V; Sivahar, V; Sitinamaluwa, HS
Wood is one of the conventional materials still used in many engineering applications. As a natural material, it is subjected to dynamic property variations. One of the major reasons for the property variation of wood is the moisture absorption. The main aim of this research is to estimate the degree of decay in the compressive strength of selected wood types against the amount of moisture using ultrasound waves. Teak (Tectonagrandis), a hardwood and Pine (Pinusthaeda), a softwood are two types of wood which are commonly used in Sri Lankan wood industry. Samples of each wood type were kept for moisture absorption and the ultrasonic pulse velocities were measured in each sample. A 54 kHz normal probe was used. Through transmission technique was carried out in longitudinal and transverse directions. The corresponding compressive strength was also tested for each moisture level in the defined directions. In the transverse direction, ultrasonic velocity and compressive strength showed relatively lower values than those in the longitudinal direction. The ultrasound velocity was found to drop with the increase in moisture content. The rate at which the velocity drops changed at a particular moisture content. It was noted that this moisture content is the Fiber saturation point (FSP) of the wood tested. This phenomenon is common for both the wood types in both the directions. The fiber saturation point of each sample was confirmed with DSC (Differential Scanning Calorimetric) analysis. The established relationships can be used to estimate the compressive strength of wood nondestructively for a known moisture content.
item: Conference-Abstract
Determine the relationship between corrosion rate and grain size of low carbon steel
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Sivasangaranathan, V; Sirinatha, DR; Sivahar, V; Abeygunawardana, AAGA
There are few studies on the effect of grain size on the corrosion rate of low carbon steel. In the current work, a series of grain sizes have been obtained in typical low-carbon steels through simple heat treatment. As we all know, grain refinement can improve strength and wear resistance. The inherent processing involved in grain refinement will change the volume and surface area of the material, resulting in changes in grain boundary density, orientation and residual stress. Ultimately, these surface changes will have an impact on the electrochemical behavior, thereby affecting the corrosion sensitivity. A large number of studies on the effect of grain size on corrosion have proved this, covering a variety of materials and test environments. However, the basic understanding of how grain refinement affects the corrosion resistance of steel, and more generally, how grain size affects the corrosion rate of low carbon steel, is very limited. The existing literature is often contradictory, even within the same steel category, and to a large extent lacks a consistent understanding of how grain size affects corrosion response. It is necessary to consider whether or how changes in grain size affect the behavior of specific steel in a specific environment.
item: Conference-Abstract
Development of a computer software for polymer composite mechanical properties analysis
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Mudalige, SP; Sanjeewa, PVGI; Weragoda, VSC; Sivahar, V
This research investigates the development of a software application designed for the analysis of polymer composites and the estimation of their mechanical properties, specifically the elastic modulus and tensile strength. In response to the need for accessible and efficient computer applications in composite analysis, this study focuses on developing a software which employs scanning electron microscopy (SEM) micrographs of the composites to extract relevant data. The software utilizes image processing techniques to accurately identify spherical particles within the composite and offers estimations for the elastic and shear modulus as well as tensile strength values. It is particularly suitable for the analysis of composites consisting of randomly oriented spherical particles, as well as those reinforced with short fibers. The mathematical models employed in the software, derived from previous calculations, allow for the estimation of the elastic modulus, shear modulus, and Poisson's ratio of the composite. The software also provides additional features to enhance its reliability and user experience. Furthermore, to ensure accuracy and reliability, the software underwent validation by comparing its predictions against literature-based real values. The developed software application addresses the need for accessible and efficient computer applications in the field of mechanical data extraction from polymer composites. It offers a user-friendly interface and advanced algorithms for analyzing SEM micrographs and extracting key mechanical properties quickly and efficiently. The software provides researchers and engineers with a valuable tool for efficient analysis and characterization of composite materials, contributing to advancements in the field of composite research.
item: Conference-Abstract
Development of a lab scale dynamic mechanical analyzer
(Department of Materials Science and Engineering, 2019-01) Rathnayaka, RMPC; Madushani, HDT; Weragoda, VSC; Sivahar, V; Sitinamaluwa, HS
Dynamic mechanical properties refer to the response of a material when it is subjected to a periodic strain. Dynamic mechanical analysis (DMA) is an important technique used to measure the mechanical and viscoelastic properties of materials such as thermoplastics, thermosets and elastomers. The aim of this research is to study the Dynamic Mechanical behavior of elastomer compounds by developing a lab-scale dynamic mechanical analyzer. The apparatus was designed to record a test specimen's reaction force when a systematically varying gradual strain development is applied. The phase difference between the applied strain and the material's response in terms of force was used to estimate the storage modulus and loss modulus to analyze the material properties. Furthermore, the dynamic modulus, dynamic loss modulus, and the mechanical damping coefficient of the elastomer could be estimated using the developed dynamic mechanical analyzer. The values obtained using the developed apparatus showed a fairly good agreement with the values for the same compound obtained from Prescott instruments ODR. The deviations were within 3.5%. One of the major shortcomings of the apparatus was the fact that the operating frequency was limited to IHz and there is no provision for carrying out measurements in varying temperature conditions.
item: Conference-Abstract
Development of a low cost, static light scattering based nano-particle size analyzer
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Anuradha, SKA; Ishan, HHA; Amarasinghe, DAS; Sivahar, V
A machine based on Static Light Scattering theories was developed for the cost effective and efficient Quality Control of the average particle size of nano-particles used in different manufacturing industries. In particular the instrument was adapted to measurement of carbon black filler used in rubber compounding. Carbon blacks are amorphous quasi graphitic particulates of the nanometer scale whose mean particle size affects the reinforcement, conductivity pigmentation and UV resistance properties of the rubber. The instrument would enable local rubber compounding companies to independently monitor and control the average particle size of the filler. The system is semi-autonomous and measures approximately 29cm × 23cm × 17.5cm and weighs approximately 4.2 kg. The instrument accepts a solution of nano-particles. Adjusts the solution concentration automaticallyand measures the scattered intensity of light which it used to calculate the particle size. The system comprises of a fluidics module that handles the pumping and dilution of solutions, an optics module that generates and detects the light and a control & power supply module that operates the other components and supplies the right voltages to them. These modules are housed in a corrosion protected steel frame and an aesthetically appealing enclosure. Key features of the instrument are a self diagnostic system, a modular structure, a graphical user interface with record keeping facility and extendibility to other particle size control applications. It is of a modular design and has been constructed with the ease of maintenance and accessibility to internal hardware, and manufacturability in mind. The components selection was based on the optimization of performance parameter, size and cost. Mechanical, thermal and vibration stabilities were considered in the design.
item: Conference-Abstract
Development of a low-cost ceiling material based on local rice husks and waste plastics
(Department of Materials Science and Engineering, 2020-02) Lakmal, TCT; Chathurika, KPI; Udayakumara, SV; Abeygunawardane, AAGA
In the modern world, plastics play a dominant role among all other types of materials. However, not like other materials, plastics take long time to degrade in normal environmental conditions. Plastics used in packaging industry are often discarded to the environment and generates many environmental issues. Due to these issues, past few years many researches focused on recycling and reusing waste plastics. One of the main methods of recycling plastic is making composites. This study was focused to develop a composite material for ceiling sheets using virgin and waste low-density polyethylene and local rice husk. The rice husk- LDPE composite samples were made by using compression moulding techniques after mixing different proportions of rice husk with LDPE. Tensile strength, Flexural strength, swelling, water absorption, Impact strength, hardness and thermal conductivity were checked for all the samples. Results show increasing of hardness, swelling, water absorption and thermal conductivity and reduction of tensile strength, flexural strength, and impact strength with increasing percentage of rice husk. According to the test results, Sample with 20:80 rice husk to LDPE ratio shows better results to use as ceiling materials based on the test results.
item: Conference-Abstract
Development of a method to measure contact angles of sessile droplets to analyze and enhance the surface wettability of nichrome
(Department of Materials Science and Engineering, 2020-02) Kumarasiri, AAAP; Amarasinghe, DAS; Attygalle, D; Abeygunawardane, AAGA
Nichrome (Ni/Cr) alloys are used in many industrial applications due to their better electrical properties and commercial availability. It is a known fact that these alloys are having a surface passivation layer of chromium oxide (Cr2O3). This oxide passivation layer changes the surface tension of the metal surface, therefore, decreases the surface wettability during soldering. This phenomenon is critically addressed in electronic applications because the wettability inhabitancy of nichrome thin films tends to reduce the solderability of the metal. The decrease in solderability will lead to many difficulties such as poor connecting strength of wires and fluctuations of resistance. In this study, two approaches were introduced to enhance the wettability of nichrome alloy surface. In the first approach a liquid salt solution was used in an acidic environment (ZnCl2/HCl) to remove the oxide passivation layer, thereby, to enhance the wettability of the nichrome alloy. Lead-free industrial solder alloy, SN100C (Sn / Cu 0.70% / Ni 0.06% / Ge 0.005%.) was used as the soldering material for this experiment. Solder drops were formed on the Nichrome thin film (With and without treatment of (ZnCl2/HCl) in 325-350°C temperature range. The second approach was an electroplating process to form a thin nickel coat (3 μm) on the nichrome surface. A two-step plating process was carried out. Various plating conditions such as pH- condition, thickness and current density were controlled of the watts bath to obtain the best wettability and adhesion. An experimental setup together with an image processing software was developed to process the image of the solder droplet and measure the contact angles of the nichrome-solder alloy interface. The contact angle measurements were based on the sessile droplet method. The polynomial and ellipse fitting methods were used to digitize the drop shape.The results of the study show that the contact angles of solder droplets were reduced by more than 50 percent after the ZnCl2/HCl treatment. Contact angles can be reduced by more than 60 percent by nickel electroplating. Therefore, the solderability of the nichrome alloy is significantly enhanced by both treatments.
item: Conference-Abstract
Development of a methodology to identify repairable photoreceptor drums
(Department of Materials Science and Engineering, 2020-02) Sampath, WGC; Senarath, GN; Attygalle, D; Abeygunawardane, AAGA
Toner cartridges are discarded due to the degradation of the organic photoconductor while the other parts of the cartridge are in usable condition. This research is focused on developing a method to identify repairable drums. Since the condition of the used drum is unknown, identifying the primary cause for the quality deterioration of xerographic prints is of great importance in repairing these drums.The print quality deterioration can happen due to deterioration of charge transport layer alone,degradation of charge generation layer alone, or occurance of both simultaneously.The damaged charge transport layer could lead to a higher residual potential due to trapped charges in the charge transport layer, and that finally affect the print quality. A locally fabricated setup was used to obtain dark decay curves and photoinduced discharge curves. These curves were then used to identify repairable drums successfully. Furthermore, the wear-out thickness of the charge transport layer was also estimated using the same data. This information was then used to develop a repair methodology for the damaged drums.
item: Conference-Abstract
Development of a photosensor based on photo dielectric effect of cadmium sulphide
(Department of Materials Science and Engineering, 2019-01) Kumari, TID; Jayasumana, MASD; Attygalle, D; Sivahar, V; Sitinamaluwa, HS
A photosensor is an electronic component that detects the presence of visible light, infrared transmission (IR), and/or ultraviolet (UV) energy. A photosensor which changes its electrical capacitance in the presence of visible light was developed based on the photo-dielectric effect of Cadmium Sulphide (CdS). This photosensor was fabricated by depositing a CdS thin film on Fluorine-doped Tin Oxide glass (FTO glass). FTO acts as the front electrical contact and an aluminum sheet acts as the back contact, where a 2.0)im - 3.0)im thick CdS thin film acts as the photo-dielectric material. Chemical bath deposition method was used for CdS fabrication and the CdS thin film with optimum photovoltaic and micro structural properties was obtained at a bath temperature interval of 40 - 45 °C, annealing temperature of 180-220 °C. Film thickness was varied by adjusting deposition time and the number of coatings. Thickness variations were determined using a Scanning Electron Microscope (SEM). The transmittance and absorbance spectra are recorded in the range of 200 nm - 1100 nm. CdS thin film fabricated under optimum conditions resulted in a bandgap in the range of 2.30 eV-2.40 eV, which is closely agreeing to the theoretical value of 2.42eV. The photo-capacitance and photoconductivity were measured in a frequency range of 1 kHz to 5 MHz in dark and illuminated conditions. The Cole-Cole plots were analyzed to identify the most sensitive operational frequency for the device.