Browsing by Author "Amarasinghe, DAS"

Now showing 1 - 20 of 73

item: Conference-Full-text
Atmospheric cold plasma to improve printability of polyethylene terephthalate
(IEEE, 2021-07) Sandanuwan, T; Hendeniya, N; Attygalle, D; Amarasinghe, DAS; Weragoda, SC; Samarasekara, AMPB; ; Hemachandra, K; Adhikariwatte, W; Rathnayake, M
Though paper is still the most common substrate in the printing industry, polymeric substrates are becoming common by the day. Commercially available polymers such as polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polypropylene (PP) surfaces have lower density of polar functional groups. Thus, the adhesion characteristics of these materials are naturally poor. Consequently, producing a quality print on such polymer substrates has become a challenge. Hence, surface modification has become a necessity for such surfaces. This study investigates the technical viability of cold plasma-based surface treatment technologies on polymeric materials. The effect of plasma pre-treatment, on the printability of PET substrates, was studied. The surfaces of these polymer substrates were subjected to different cold plasma treatments, using 80% N2 and 20% O2 as feed gas. The study covers the effect of the plasma dose and the plasma intensity on the printability and the degree of surface modification. The study determined the optimum plasma conditions for quality and durable prints.
item: Conference-Full-text
Atmospheric pressure plasma treatment as a cost-effective and eco-friendly pre-treatment method to enhance seed perfomance in germination and early seedling growth
(IEEE, 2021-07) Hendeniya, N; Sandanuwan, T; Amarasinghe, DAS; Attygalle, D; Weragoda, S; Ranaweera, B; Rathnayake, K; Lalanka, M; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Novel methods of improving the seed quality have gained a lot of attention recently, cold atmospheric pressure plasma being one of the most promising methods. The effects of cold atmospheric pressure plasma treatment of chili - MI 2 (Capsicum annuum L.) and snake gourd - MI short (Trichosanthes cucumerina) seeds have been compared with a conventional fungicide seed coating and a biological coating treatment. The plasma exposure times used were 4min, 6min and 10min. Cold atmospheric pressure plasma treatment has shown improved effects on seed germination for both Capsicum annuum L. and Trichosanthes cucumerina seeds. Both seed types showed the best germination results under 6 min treatment while displaying the best Seed Vigor Index through 4 min plasma treatment. Compared with the coating treatments, cold atmospheric pressure plasma has shown a significant stimulation in seed germination and early growth.
item: Conference-Full-text
Chemical modification of microcrystalline cellulose using sunflower oil
(IEEE, 2020-07) Rathnayake, WSM; Karunanayake, L; Samarasekara, AMPB; Amarasinghe, DAS; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Structural, thermal, physical and mechanical properties of microcrystalline cellulose (MCC) combined with its biodegradability make an excellent platform for the aptness of MCC in reinforcing polymeric composites along with a commercial success in the context of green chemistry. Main drawback of above union is the incompatibility of hydrophilic MCC and hydrophobic polymers which ultimately damp the desired property improvements. With a prospective and pioneering a green approach, this study introduces a novel method to modify the surface of MCC to introduce surface hydrophobicity. State of the treatment was analyzed with acyl percentage, FTIR analysis, wettability test, SEM images and TGA thermographs. Results uphold the success of the transesterification reaction of sunflower oil ethyl esters (SFEEs) with MCC showing higher attraction to nonpolar dichloromethane with an improved thermal stability. FTIR showed the successfully grafted SFEEs onto MCC surface. Modified MCC can be used in the fabrication of polymeric substances in the process of improving its mechanical properties simultaneously under green chemistrybased approach.
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 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 an exhaled breath analyzer for early detection of diseases
(Department of Materials Science and Engineering, University of Moratuwa., 2023) Panawala, PSS; Tissera, PIU; Amarasinghe, DAS; Sivahar, V
Chronic Kidney Disease (CKD) represents a significant global health burden, with early detection being crucial for effective management and improved patient outcomes. This research focuses on the development of an Exhaled Breath Analyzer (EBA) as a non-invasive and potentially cost-effective tool for early detection of CKD. Ammonia (NH3) has been identified as a key marker in exhaled breath to diagnose CKD patients as the concentration of ammonia among healthy people is about 0.5-5 ppm and in CKD patients it can be more than 25 ppm. In this work, an ammonia gas sensor based on Polyaniline (PANI) was fabricated using a custom made Interdigitated capacitive sensor (IDC-S). PANI films were successfully deposited on the IDC-S using the solution casting method. The sensor responded to a low ammonia concentration of 50 ppm with a capacitance change of 10% with respect to capacitance in air in room temperature. Furthermore, the response of the sensor increased to 44% as the concentration increased to 300 ppm. This showed a good linear relationship between sensor response and ammonia concentration. Furthermore, the effect of relative humidity on the sensor was also studied and a significant change in capacitance of the sensor was observed with changing relative humidity levels. Moreover, the sensor response to a fixed ammonia concentration of 200 ppm at different humidity levels was studied and it diminished from 26% to 4% as the humidity level increased from 20% to 90%.
item: Conference-Abstract
Development of an exhaled breath analyzer for early detection of diseases
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Panawala, PSS; Tissera, PLU; Amarasinghe, DAS; Sivahar, V
Chronic Kidney Disease (CKD) represents a significant global health burden, with early detection being crucial for effective management and improved patient outcomes. This research focuses on the development of an Exhaled Breath Analyzer (EBA) as a non-invasive and potentially cost-effective tool for early detection of CKD. Ammonia (NH3) has been identified as a key marker in exhaled breath to diagnose CKD patients as the concentration of ammonia among healthy people is about 0.5-5 ppm and in CKD patients it can be more than 25 ppm. In this work, an ammonia gas sensor based on Polyaniline (PANI) was fabricated using a custom made Interdigitated capacitive sensor (IDC-S). PANI films were successfully deposited on the IDC-S using the solution casting method. The sensor responded to a low ammonia concentration of 50 ppm with a capacitance change of 10% with respect to capacitance in air in room temperature. Furthermore, the response of the sensor increased to 44% as the concentration increased to 300 ppm. This showed a good linear relationship between sensor response and ammonia concentration. Furthermore, the effect of relative humidity on the sensor was also studied and a significant change in capacitance of the sensor was observed with changing relative humidity levels. Moreover, the sensor response to a fixed ammonia concentration of 200 ppm at different humidity levels was studied and it diminished from 26% to 4% as the humidity level increased from 20% to 90%.
item: Conference-Abstract
Development of antimicrobial materials for food packaging applications
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Senarath, SMNS; Madushani, SPA; Samarasekara, AMPB; Amarasinghe, DAS; Sivahar, V
The rising demand to increase fresh food shelf life as well as the need of protection against foodborne diseases urged the development of antimicrobial food packaging. Nanomaterials have increasingly being used in food packaging applications in recent years due to their extraordinary properties when compared to bulk materials. Nanoparticles provide signi? cant antimicrobial properties in different environmental conditions. Nowadays, there is heighten attention in designing nano particles incorporated food packaging with the introduction of nanotechnology. Silver nanoparticles (AgNPs) based antimicrobial packaging is an innovative form of food packaging used to extend shelf-life of food and reduce the risk of pathogens. AgNPs are one of the most powerful antimicrobial agents which can be used for increasing shelf life of foods due to its capacity to eliminate infectious micro-organisms. The present research work is based on the preparation of silver nanoparticles incorporated coating for polymer based packaging components. Nano Silver impregnated cross-linked polyvinyl alcohol coating was synthesized and applied on the polymer surface. In this study, wettability of the polymer surface was enhanced by a UV treatment. Contact angle was measured to confirmation of the wettability. The adhesion of the coating to polymer was obtained as load required to peel off the coating. Optimum UV treatment time was selected by using contact angle measurements and load required to peel off the coating. Thermal degradation of cross-linked Nano silver coating was determined using thermo gravimetric analysis. Presence of silver nanoparticles in the coating was confirmed by Surface Plasmon Resonance (SPR) and Scanning Electron Microscopy (SEM). The nano silver incorporated polymer was tested for its biocidal action against model bacteria Escherichia coli using zone inhibition and food contain in nano silver coated containers. Developed nano silver incorporated polymer based food packaging products showed antimicrobial properties. This developed product can be used to improve the quality of the food and extend shelf life especially in food packaging applications.
item: Conference-Abstract
Development of cellulose based light weight polymer composites
(2017) Rajapaksha, LD; Saumyadi, HAD; Samarasekara, AMPB; Amarasinghe, DAS; Karunanayake, L
Polymer matrix composites are used in most of the engineering structures today. This type of composite consists of reinforcing materials in polymer matrix. There is an increasing demand for environmentally friendly reinforcing materials to reduce the cost of traditional fibers. Cellulose is a natural polymer material. Cellulose is used as filler for the reinforcement of polymer materials. Microcrystalline cellulose is a branch of cellulose. Objective of this research is to develop and characterize polypropylene and microcrystalline cellulose based composite. Silane surface modification technique was used to modify the cellulose surface. Surface modified cellulose was mixed polypropylene materials with different compositions. Physical and mechanical properties of the developed product were measured by tensile, impact, hardness, density and water absorption tests. According to the experimental results, there is a gradual reinforcing effect with increase of cellulose' concentration. Water absorption and hardness results showed increase of water absorption and hardness with increase of cellulose concentration. There is a gradual reduction of density of the develop product with increase of cellulose concentration. 5 wt% sample showed the lowest density value and weight reduction is about 13%. This type of composite can be used for light weight strstructure design especially in load bearing applications.
item: Conference-Abstract
Development of cellulose-based precursor solution for electrospinning technique
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Basnayaka, BMCGK; Udeshini, AA; Samarasekara, AMPB; Amarasinghe, DAS; Abeygunawardana, AAGA
To electro-spin a polymer solution, certain specific conditions need to be met, for example, acetyl content (A) (38- 40%), degree of substitution (DS) (2.3-2.5), molecular weight(M) (30,000 100,000 gmol-1) solution system of CA 15w%, acetone 80w% and water 5w%. This study aimed to produce an electro-spinnable cellulose acetate precursor solution from raw cotton. This paper discusses the cellulose extraction process as well as the characterization process. The electro-spun cellulose acetate fibers are significantly crucial to high-tech product designs.
item: Conference-Abstract
Development of graphene oxide based capacitive gas sensor for selective detection of NO2
Gunasena, RGSP; Deemantha, MBA; Amarasinghe, DAS; Attygalle, D
NO2 gas is a harmful vapor that, when present in large quantities, can impose severe threats on health and environment. Gas sensors for NO2 have been in development over the past few decades albeit selectivity towards the gas still remains somewhat unperfected. A method was suggested to improve selectivity towards NO2 by registering a unique and recurring feature of the signal behavior as the selection criterion i.e. gradient of sensor response. A parallel plate capacitive gas sensor was fabricated taking graphene oxide as the dielectric medium and was tested for NO2. Graphene oxide was synthesized adhering to the Improved Hummer’s Method (Tours Method) which produced sufficiently oxidized graphene with a yield of 193% with respect to the starting material. Synthesized graphene oxide was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA) and X-ray Diffractometry (XRD) techniques ascertaining that the products were well oxidized with acceptable d-spacing values. Sensor assembly was tested for capacitance variation in the frequency domain, time domain and under the influence of constant temperature ramp. The results showed an average response time of about 1 minute to reach the steady state signal and an equal time to go back to the initial reference signal level once the target gas was evacuated. Keywords— graphene oxide, capacitive sensor, selective sensing, FTIR
item: Conference-Abstract
Development of Graphene Oxide based capacitive gas sensor for NO2 detection
(Department of Materials Science and Engineering, 2019-01) Deemantha, MBA; Gunasena, RGSP; Amarasinghe, DAS; Sivahar, V; Sitinamaluwa, HS
Parallel plate capacitive gas sensor was assembled using Graphene Oxide (GO) as the transducer material. The sensor was tested with NO2 as the target gas. GO was synthesized according to the Improved Hummer's Method (Tours Method) in which vein graphite was sufficiently oxidized. Synthesized graphene oxide was characterized by Fourier Transform Inirared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) ascertaining that products were well oxidized. Sensor was tested for capacitance variation in the fi^equency and time domains under the influence of constant temperature ramp. The results showed an average response time of about 2 minutes to reach the steady state signal and an equal time to reach the initial reference signal levels once the testing chamber was evacuated of the target gas.
item: Conference-Abstract
Development of metal oxide based solid state gas sensor platform
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Udaraka, MPSD; Nanayakkara, HATV; Attygalle, D; Amarasinghe, DAS; Sivahar, V
Gas sensors are chemical sensors which have a transducer and an active layer for converting the chemical information into another form of electronic signal. Gas detection and determining the composition of a gas in a mixture is necessary in many different fields. In this research, development of metal oxide based sensing material layer and design of sensor platform were on focus. SnO2 was selected as the main precursor of the sensing material and Mn as the dopant. Material deposition was done by spin coating method on soda lime glass substrate. The complete platform consists of sensor material, heating element, temperature monitoring and control unit, Arduino board for data acquisition and signal processing. The temperature dependence of resistivity of SnO2 film was studied in detail in the presence of different gases and gas mixtures. The results shows that the Mn doped spin coated SnO2 thin film is a promising method for the preparation of high quality ethanol sensor even in a mixture of ethanol and acetone. Optimum sensitivity for ethanol was obtained at 140 0 C - 160 0 C temperature range.
item: Conference-Abstract
Development of nano silver impregnated food packaging materials
(Department of Materials Science and Engineering, 2019-01) Samarasekara, AMPB; Amarasinghe, DAS; Madhushan, WKP; Chathuranga, SN; Sivahar, V; Sitinamaluwa, HS
The growing demand for increased shelf-hfe of food and the need for protection against foodbome diseases, fiiel the development of new food packaging materials. Silver-nanoparticle (AgNp) impregnated packaging materials are promising candidates for active food packaging. These active packaging materials are capable of extending the shelf-life of foods and reducing the risk of pathogens. The current research work is focused on the development of AgNp incorporated coating for polymer-based food packaging. AgNp dispersed in polyvinyl alcohol solution was prepared by in situ reduction method, in which silver nitrate and polyvinyl alcohol (PVA) acted as precursor and capping agent respectively. Presence of silver nanoparticles in the solution was confirmed by photoluminescence spectroscopy and UV-Vis spectroscopy. In order to reduce coating solubility PVA solution was cross-linked. The compatibility of the coating with the substrate was enhanced by plasma treatments. Contact angle measurements were employed to monitor the wettability changes. The solubility of the coating was examined by gravimetric methods. The effects of cross-linked temperature and cross-linked agents on solubility were studied. The presence of silver nanoparticles in the coating was confirmed by surface plasmon resonance and electron micrographs. The modified Kirby-Bauer (disk diffusion) method was employed to measure the anti-bacterial effect of the coating.
item: Conference-Abstract
Development of spark emission spectrometer to identify an alloy
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Gunerathne, MGGM; Karunasena, DBTK; Attygalle, D; Amarasinghe, DAS; Sivahar, V
Spark optical emission spectrometer (OES) is a widely used technique in identifying alloy compositions of metals. Based on the OES principle, a low-cost spark, portable and fully automated spark optical emission spectrometer was developed. A 1000kV ultra-high voltage arc generator coil module was used as the excitation source and a CMOS (complementary metal-oxide semiconductor) image sensor was used as the spectral detector in this spark OES. Data collection and interfacing was done through a Raspberry Pi Single-board Computer. Analysis of wavelength and intensity data were performed using an algorithm coded in python programming language. The program presents the alloy elements and their quantities. Three main factors that limits the precision and accuracy of results were identified as the excitation source, the resolving powers of the spectrometer and the electronic noise characteristics of the systems.
item: Conference-Full-text
Direct current resistivity based in-situ cure monitoring technique for amine cured epoxy resins
(IEEE, 2022-07) Herath, HS; Janith, GI; Weragoda, VSC; Amarasinghe, DAS; Attygalle, D; Samarasekara, AMPB; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The Epoxy resins and epoxy resins-based system usage in industrial applications such as composites and electronic materials keep growing. Thus, research focused on enhancing the properties of these resin-based systems is of importance for manufacturing quality controls. Especially monitoring of cure progression and chemo-rheological behavior of epoxy resins are essential for many industries. Commonly practiced cure monitoring methods such as DSC and DMA for the purpose are conducted in laboratories under specified conditions and are not practiced for real-time cure monitoring. However, in-situ cure monitoring techniques are essential for many industries as they provide more insight and thus more control over processing parameters. This study introduces a direct current resistivity-based cure monitoring method as it is simple, cost-effective, reliable, and more importantly, industry-friendly. The fast response of direct current measurements combined with the simplicity of the analysis makes this method suitable for real-time sensing applications. The strong correlation between the degree of cure and the viscosity allows us to take simultaneous measurements of both. The method's feasibility was analyzed using two amine cured epoxy resin systems.
item: Conference-Full-text
Effect of annealing on temperature coefficient of resistance of cu-ni foil as strain gauge material
(IEEE, 2023-12-09) Satheekshana, W; Weragoda, SC; Amarasinghe, DAS; Samarasekara, AMPB; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Near zero Temperature Coefficient of Resistance (TCR) is an increasing concern in the strain gauge manufacturing industry. The purpose of this study is to investigate the connection between the TCR of the Strain Gauge (SG) and the annealing temperature of the foil used to manufacture the strain gauge. Constantan foils were heat treated, under a nonoxidizing annealing environment. The TCR of the manufactured foil-strain gauges were calculated in the range of -10°C to 40°C. The TCR values were shifted from negative to positive with annealing temperature. This study provides a conclusive response to the question concerning the effect of annealing temperature of Constantan foil for the manufacturing of strain gauges with near zero TCR.
item: Conference-Full-text
Effect of particle size distribution of rice straw on cellulose extraction
(IEEE, 2020-07) Ratnakumar, A; Samarasekara, AMPB; Amarasinghe, DAS; Karunanayake, L; Weeraddana, C; Edussooriya, CUS
Cellulose has become a wonder material in the present context of research and development since it is fibrous and tough, hence biodegradable, biocompatible, and renewable natural polymer which can be employed in various industrial applications. Nowadays, rice straw as a cellulose source has gained momentum as rice is one of the major crops grown in most of the tropical and subtropical countries of the world with half of the world population consuming it as the major food source. Chemical extraction and purification method is found to be the most efficient method for cellulose extraction from lignocellulosic biomass. Therefore, it is of paramount important to investigate the influence of parent materials on the synthesis process and the properties of the yield. In this research, effect of particle size distribution of locally available rice straw on cellulose synthesis was studied. Study revealed that after the series of chemical treatments M-75 yielded 27.19 ± 0.98 percent, M-250 yielded 38.31 ± 0.86 percent and M-H yielded 33.68 ± 0.68 percent cellulose. FTIR analysis revealed the sequential and complete removal of lignin (1516 cm−1, aromatic skeletal vibrations), hemicellulose (1729 cm−1, carbonyl stretching) and silica (796 cm−1, Si–O–Si stretching) thus, confirms the final product as cellulose. SEM images showed that M-75 exhibited whisker like structure whereas M-250 showed fibrillar network structure. These findings will have profound influence upon extracting cellulose from agricultural biomass.
item: Conference-Full-text
The effect of surface topology on the edl capacitance: 1_d case
(IEEE, 2022-07) Amarathunga, AAS; Malshan, LPJ; Amarasinghe, DAS; Attygalle, D; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
An electrical capacitor is an energy storage device that generates an electric field between electrodes and produces potential that can be channeled through associated circuits. The Electrical Double Layer (EDL) capacitor is a unique capacitor with a remarkably higher capacity. The energy densities of these capacitors can range between 0.5 and 10 Wh/kg. This study develops a method to predict the dependence of the double-layer capacitance on the roughness profile of the electrode using the linear Poisson-Boltzmann theory, and the Gouy-Chapman theory for 1-D systems. The roughness dependence of diffuse layer differential capacitance is obtained for a defined roughness profile. The theory developed here helps to understand the Debye-length dependent on the roughness factor and profile. The variation of double-layer capacitance with roughness is analyzed based on a numerical solution obtained for the model roughness profile.
item: Conference-Full-text
Effects of current density on the solder wettability of nickel electrodeposited ni20cr alloy
(IEEE, 2021-07) Kumarasiri, A; Herath, HS; Amarasinghe, DAS; Attygalle, D; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Nickel-chromium alloys are in high demand in the electrical industry, as they have some favorable electrical properties. The formation of a thin chromium oxide layer on the alloy surface protects the alloy from further oxidation. The passivation layer formation is almost instantaneous when exposed to the ambient atmosphere. It prevents the strong bonding between the solder and the substrate due to the alteration of the substrate's surface energy by the passivation layer. Poor solderability could cause short-circuiting and resistance variations in electrical devices. This paper reviews the effect on solderability due to the passive layer formation and proposes solutions to overcome the problems caused by this layer. The introduction of solder-compatible metal layers such as Ni onto the substrate surface is a way to overcome this. However, solder-compatible metals such as Ni cannot be introduced with conventional electroplating baths due to the alloy's passive behavior. Therefore, a breakdown of the passivity is required before the nickel coating. A three-bath electrodeposition strategy comprising; pre-cleaning, activation, and electroplating, were used to achieve the task. The study examines the dependency of solder wettability on the current density, using an in-house fabricated contact-angle measuring device and analytical software.