Microstructural and Creep Characterization of Sn-0.7Cu and Sn-0.7Cu-xBi Lead-free Solders for Low Cost Electronic Applications

2021 ◽  
Author(s):  
Shakib Alsowidy ◽  
Ahmed M. Aljarbani ◽  
Mohammed S. Gumaan
Keyword(s):  
Electrical Conductivity ◽  
Creep Resistance ◽  
Low Cost ◽  
Testing Machine ◽  
Sem Analysis ◽  
Dislocation Creep ◽  
Creep Tests ◽  
Mean Values ◽  
Three Samples ◽  
Two Phases

Abstract The microstructural, creep resistance and electrical conductivity properties of Sn-0.7Cu eutectic alloy with Bi-additions in concentrations (0.3 and 0.5 wt.%) have been investigated using x-ray diffraction (XRD), Scanning electron microscope (SEM), creep testing machine and (DC) circuit respectively. The three samples were prepared from high purity (99.99%) elements Sn, Cu, and Bi using melting technique. XRD and SEM analysis showed that the eutectic Sn-0.7Cu alloy composed primarily of two phases; a body centered tetragonal 𝜷-Sn phase and monoclinic IMC Cu 6 Sn 5 , the additions of 0.3 and 0.5 wt.% Bi to the eutectic Sn-0.7Cu promote the formation of IMC Cu 6 Sn 5. The above motioned Bi additions have refined the 𝜷-Sn particle size. Creep tests showed that the creep strain rate increases and the creep lifetime (rupture time) decreases as the applied stress and temperature rises. Improvements in creep resistance solders have been achieved by increasing the Bi content up to 0.5 wt. %. The mean values of stress exponent and activation energy indicate that the dislocation creep is the dominate controlling mechanism. The electrical conductivity of the samples was calculated at room temperature, it has the highest value with 0.3 wt.% of Bi.

Microstructure and Creep Properties of Selected Gravity Casting Magnesium Alloys

2016 ◽  
Vol 682 ◽  
pp. 372-379
Author(s):  
Tomasz Rzychoń
Keyword(s):  
Magnesium Alloys ◽  
Creep Resistance ◽  
Low Cost ◽  
Xrd Analysis ◽  
Phase Identification ◽  
Creep Tests ◽  
Gravity Casting ◽  
Creep Properties ◽  
Transmission Electron ◽  
Primary Crystals

In this paper microstructure and creep properties of Mg-Al-Ca-Sr, Mg-Zn-RE-Zr and Mg-Sn-Si gravity casting magnesium alloys are presented. The microstructure was characterized using light microscopy, scanning and transmission electron microscopy. Phase identification was made by SAED and XRD analysis. Creep tests were carried out in the temperature range from 180°C to 200°C at applied stress of 60 MPa. Microstructure of Mg-Al-Ca-Sr alloys composed of α-Mg grains and C36, C15 and C14 intermetallic compounds in the interdendritic regions. In case of Mg-Zn-RE-Zr alloys the dominant intermetallic compound is (Mg,Zn)12RE phase also located in the interdendritic regions. Microstructure of Mg-Sn-Si alloys after T6 heat treatment consists of plate-like precipitates of Mg2Sn phase, primary crystals of Mg2Si phase and globular Mg2Si phase. Among the alloys in this study, the low-cost Mg-5Al-3Ca-0.7Sr alloy has the best creep resistance. The other alloys, excluding the Mg-5Si-7Sn alloy, are characterized by a poorer creep resistance in compared to Mg-5Al-3Ca-0.7Sr alloy, however their creep resistance is better if compared to typical Mg-Al alloys. Creep resistance of Mg-5Si-7Sn alloy is very low.

Dislocation Creep in Al-22.2, 53.6 and 101 at.ppm Fe Solid Solution Alloys

2014 ◽  
Vol 922 ◽  
pp. 749-754
Author(s):  
K. Takeshima ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Creep Resistance ◽  
Dislocation Creep ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Range ◽  
Creep Tests ◽  
Ultra High Purity ◽  
Dominant Deformation Mechanism

Creep tests of ultra-high-purity (99.999%) Al and Al-22.2, 53.6, 101 at.ppm Fe solid solution alloys were conducted at 773 K in the stress range of 2-6 MPa in order to investigate effect of solute Fe on high temperature deformation of Al. Creep resistance was enhanced by addition of Fe in solid solution. The stress exponents of the samples exhibited values of about 5, which indicate that climb-controlled dislocation creep was dominant deformation mechanism. It could be suggested that Fe atoms segregating in dislocations due to the strong interaction between solute Fe atoms and the dislocation enhanced the creep resistance.

An Experimental Model on the Biomechanical Behaviour of the Flexor Tendons in New Zealand Rabbits

2017 ◽  
Vol 22 (03) ◽  
pp. 320-328
Author(s):  
D. Skouteris ◽  
E. Magnissalis ◽  
A. Papalois ◽  
S. Varitimidis ◽  
P. J. Papagelopoulos ◽  
...  
Keyword(s):  
New Zealand ◽  
Low Cost ◽  
Adhesion Formation ◽  
Testing Machine ◽  
Middle Finger ◽  
Experimental Models ◽  
Laboratory Animals ◽  
Tensile Testing Machine ◽  
Mean Values ◽  
New Zealand Rabbits

Background: In order to introduce new pharmacological agents with the intent to inhibit the adhesion formation, it is important to test such products on laboratory animals under a protocol that can evaluate the quantitative and qualitative aspects of healing of the tendons. Most experimental models focus on the tensile strength and histological analysis of the tendons, failing to sufficiently quantify the degree of the adhesion formation. Methods: The experiment included six male New Zealand rabbits that underwent surgery of their right forepaws. The deep flexor tendon of the middle finger was transected and repaired and after six weeks the rabbits were killed. In order to assess the extent of adhesions, the functional stiffness of the tendons and the range of motion of the specimens’ fingers was studied using a tensile testing machine. The setup used allowed the simultaneous recording of the specimens’ motion and the pulling force values. Results: The mean values of the left and right forepaws were expressed in the same chart showing a clear difference between the operated and non operated forepaws. Conclusions: Using a relatively simple set up in the laboratory we had the chance to focus on a more elaborate analysis of the data with the help of low cost and accessible software.

scholarly journals The Effect of Crystal Mismatch on the Thermoelectric Performance Enhancement of Nano Cu2Se

2021 ◽  
Vol 7 ◽  
Author(s):  
Yunus Demirci ◽  
Aminu Yusuf ◽  
Bejan Hamawandi ◽  
Muhammet S. Toprak ◽  
Sedat Ballikaya
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Performance Enhancement ◽  
Sem Analysis ◽  
Total Thermal Conductivity ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Two Phases

In the past decades, Cu2−xSe compounds have attracted great attention due to the inclusion of non-toxic and abundant elements, besides having a promising thermoelectric (TE) performance. In this work, we investigated the effect of a crystal mismatch of a nanoinclusion phase on the TE properties of Cu2−xSe. Nano-Cu2Se was synthesized using microwave assisted thermolysis, while the p-type skutterudite, Fe3.25Co0.75Sb12 (FeCoSb), compound was synthesized using a chemical alloying route. Nano-Cu2Se, and (nano-Cu2Se)1−x(nano-FeCoSb)x composites, where x = 0.05 and 0.1, were prepared via mechanical alloying followed by Spark Plasma Sintering process. Structural properties were evaluated by PXRD and SEM analysis, while the high temperature transport properties were examined via electrical conductivity, Seebeck coefficient, and thermal conductivity measurements in the temperature range of 300–800 K. Powder X-ray diffraction (PXRD) confirmed a single phase of nano Cu2Se, while the samples with FeCoSb inclusion consist of two phases as Cu2Se and CoSb3. SEM micrographs of all samples show that Cu2Se has randomly oriented grains with different sizes. Cu2Se samples with a FeCoSb inclusion show a rather different structure. In these samples, a rod-shaped FeCoSb phase, with a size varying between 20 and 100 nm, showed an inhomogeneous distribution in the structure and stacked between the Cu2Se layers. Transport data indicate that crystal mismatch between Cu2Se and FeCoSb has a strong effect on the TE transport properties. Electrical conductivity decreases but Seebeck coefficient enhances with nano FeCoSb inclusion. Total thermal conductivity was suppressed by 30% and ZT value enhanced by 15% with 5% nano FeCoSb inclusion at 750 K, likely due to a decrease in the electronic contribution of the thermal conductivity. Structural and transport data show that small amount of nanoinclusion of FeCoSb has a beneficial effect on the TE performance of nano Cu2Se at temperatures below 800 K.

scholarly journals HEAT TREATMENT EFFECT ON THE CREEP OF INDUSTRIAL COPPER WIRE

2016 ◽  
Vol 22 (3) ◽  
pp. 181 ◽  
Author(s):  
Salim Gareh ◽  
Zakaria Boumerzoug
Keyword(s):  
Heat Treatment ◽  
Creep Test ◽  
Copper Wire ◽  
Dislocation Creep ◽  
Creep Life ◽  
Creep Tests ◽  
Sample Heat ◽  
Heat Treated ◽  
Three Samples ◽  
Rupture Mechanism

<p class="Default">Creep behavior of copper wire, produced by wiredrawing process in ENICAB Biskra, has been investigated by creep tests at 340°C under the stress 98,108 and 118 MPa. In this investigation, three samples have been tested: copper drawn wire non heat treated, and heat treated at 600°C and 700°C. Microstructure after the creep test was observed by optical microscopy to understand the rupture mechanism. We have found that the sample heat treated at 600 °C had a longer creep life. We have also deduced that the dislocation creep was the creep deformation mechanism of the drawn copper. SEM observations of fractured surfaces after creep tests of drawn copper wire non heat treated and  treated 10 min at 600 ° C under stress of 118 MPa.</p>

scholarly journals Transport Properties of Natural and Artificial Smart Fabrics Impregnated by Graphite Nanomaterial Stacks

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1018
Author(s):  
Carola Esposito Corcione ◽  
Francesca Ferrari ◽  
Raffaella Striani ◽  
Antonio Greco
Keyword(s):  
Electrical Conductivity ◽  
Transport Properties ◽  
Low Cost ◽  
Empirical Relationship ◽  
Theoretical Models ◽  
Expandable Graphite ◽  
Easy Method ◽  
Textile Materials ◽  
Fabric Materials ◽  
The Impact

In this work, we studied the transport properties (thermal and electrical conductivity) of smart fabric materials treated with graphite nanomaterial stacks–acetone suspensions. An innovative and easy method to produce graphite nanomaterial stacks–acetone-based formulations, starting from a low-cost expandable graphite, is proposed. An original, economical, fast, and easy method to increase the thermal and electrical conductivity of textile materials was also employed for the first time. The proposed method allows the impregnation of smart fabric materials, avoiding pre-coating of the fibers, thus reducing costs and processing time, while obtaining a great increase in the transport properties. Two kinds of textiles, cotton and Lycra®, were selected as they represent the most used natural and artificial fabrics, respectively. The impact of the dimensions of the produced graphite nanomaterial stacks–acetone-based suspensions on both the uniformity of the treatment and the transport properties of the selected textile materials was accurately evaluated using several experimental techniques. An empirical relationship between the two transport properties was also successfully identified. Finally, several theoretical models were applied to predict the transport properties of the developed smart fabric materials, evidencing a good agreement with the experimental data.

scholarly journals A Low-Cost Water Depth and Electrical Conductivity Sensor for Detecting Inputs into Urban Stormwater Networks

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3056
Author(s):  
Baiqian Shi ◽  
Stephen Catsamas ◽  
Peter Kolotelo ◽  
Miao Wang ◽  
Anna Lintern ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Depth ◽  
Asset Management ◽  
Low Cost ◽  
Rate Of Change ◽  
Urban Drainage ◽  
Urban Stormwater ◽  
High Resolution Data ◽  
Conductivity Sensor ◽  
Level Sensor

High-resolution data collection of the urban stormwater network is crucial for future asset management and illicit discharge detection, but often too expensive as sensors and ongoing frequent maintenance works are not affordable. We developed an integrated water depth, electrical conductivity (EC), and temperature sensor that is inexpensive (USD 25), low power, and easily implemented in urban drainage networks. Our low-cost sensor reliably measures the rate-of-change of water level without any re-calibration by comparing with industry-standard instruments such as HACH and HORIBA’s probes. To overcome the observed drift of level sensors, we developed an automated re-calibration approach, which significantly improved its accuracy. For applications like monitoring stormwater drains, such an approach will make higher-resolution sensing feasible from the budget control considerations, since the regular sensor re-calibration will no longer be required. For other applications like monitoring wetlands or wastewater networks, a manual re-calibration every two weeks is required to limit the sensor’s inaccuracies to ±10 mm. Apart from only being used as a calibrator for the level sensor, the conductivity sensor in this study adequately monitored EC between 0 and 10 mS/cm with a 17% relative uncertainty, which is sufficient for stormwater monitoring, especially for real-time detection of poor stormwater quality inputs. Overall, our proposed sensor can be rapidly and densely deployed in the urban drainage network for revolutionised high-density monitoring that cannot be achieved before with high-end loggers and sensors.

scholarly journals Shear bond strength of novel calcium aluminate-based cement (EndoBinder) to root dentine

2014 ◽  
Vol 08 (04) ◽  
pp. 498-503 ◽  
Author(s):  
Lucas da Fonseca Roberti Garcia ◽  
Hebert Luis Rossetto ◽  
Fernanda de Carvalho Panzeri Pires-de-Souza
Keyword(s):  
Bond Strength ◽  
Calcium Aluminate ◽  
Shear Bond Strength ◽  
Testing Machine ◽  
Mineral Trioxide Aggregate ◽  
Acrylic Resin ◽  
Promising Alternative ◽  
Mean Values ◽  
Significant Difference ◽  
Molar Teeth

ABSTRACT Objective: To evaluate the shear bond strength of a novel calcium aluminate-based cement, EndoBinder (EB), to dentine in comparison with Grey and White Mineral Trioxide Aggregate (MTA). Materials and Methods: Root canal hemi-sections obtained from 30 extracted molar teeth were embedded in self-polymerized acrylic resin and were grounded wet in order to obtain a flat dentine surface. Next, the roots were randomly assigned into three groups (n = 10), according to the cement used, as follows: EB: EndoBinder; WMTA: White MTA and GMTA: Grey MTA. The shear bond strength test was performed using a Universal Testing Machine (0.5 mm/min) and the data were submitted to statistical analysis (1-way ANOVA and Tukey tests, P < 0.05). Results: EB presented the highest shear bond strength values; however, there was no statistically significant difference in comparison with GMTA (P > 0.05). WMTA presented the lowest mean values, which were significant in comparison with EB (P < 0.05). Conclusions: The novel calcium aluminate-based cement presented higher shear bond strength than WMTA, and should be considered as a promising alternative in endodontic therapy.

scholarly journals Digital Smoke Taint Detection in Pinot Grigio Wines Using an E-Nose and Machine Learning Algorithms Following Treatment with Activated Carbon and a Cleaving Enzyme

Fermentation ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 119
Author(s):  
Vasiliki Summerson ◽  
Claudia Gonzalez Viejo ◽  
Damir D. Torrico ◽  
Alexis Pang ◽  
Sigfredo Fuentes
Keyword(s):  
Machine Learning ◽  
Activated Carbon ◽  
Low Cost ◽  
Aroma Compounds ◽  
Machine Learning Algorithms ◽  
Enzyme Treatment ◽  
Mean Values ◽  
Volatile Aroma ◽  
Carbon Treatment ◽  
Volatile Aroma Compounds

The incidence and intensity of bushfires is increasing due to climate change, resulting in a greater risk of smoke taint development in wine. In this study, smoke-tainted and non-smoke-tainted wines were subjected to treatments using activated carbon with/without the addition of a cleaving enzyme treatment to hydrolyze glycoconjugates. Chemical measurements and volatile aroma compounds were assessed for each treatment, with the two smoke taint amelioration treatments exhibiting lower mean values for volatile aroma compounds exhibiting positive ‘fruit’ aromas. Furthermore, a low-cost electronic nose (e-nose) was used to assess the wines. A machine learning model based on artificial neural networks (ANN) was developed using the e-nose outputs from the unsmoked control wine, unsmoked wine with activated carbon treatment, unsmoked wine with a cleaving enzyme plus activated carbon treatment, and smoke-tainted control wine samples as inputs to classify the wines according to the smoke taint amelioration treatment. The model displayed a high overall accuracy of 98% in classifying the e-nose readings, illustrating it may be a rapid, cost-effective tool for winemakers to assess the effectiveness of smoke taint amelioration treatment by activated carbon with/without the use of a cleaving enzyme. Furthermore, the use of a cleaving enzyme coupled with activated carbon was found to be effective in ameliorating smoke taint in wine and may help delay the resurgence of smoke aromas in wine following the aging and hydrolysis of glycoconjugates.

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