Swelling Characteristics and Tensile Properties of Natural Fiber Reinforced Plastic in Selected Solvents

The swelling behavior and tensile strength of natural fiber-reinforced plastic in premium motor spirit (PMS), dual purpose kerosene (DPK) and sea water have been studied. Composite formed by reinforcing polyester resin with Okam fibers was immersed in the selected solvents for 16 weeks (4 months). Swelling characteristics of samples of this composite material were determined by monitoring- forth nightly, changes in weight of the samples within the test period and tensile test was conducted on the samples after 16 weeks using Hounsfeild (Monsanto) tensometer. The results show that the solvents reduced the strengths of the composite with PMS giving the highest reduction in strength followed by DPK and then sea water. Reduction in strength was attributed to the weakening of the interfacial bonding between the polyester matrix and reinforcing okam fibers

Some Tensile Properties of Unsaturated Polyester Resin Reinforced with Varying Volume Fractions of Carbon Black Nanoparticles

The recent emergence of nano science and nano technology has added another dimension to the staple of the modern composite technology. Instead of micron diameter fibres and particles, nano particles are being incorporated into polymer matrices to form a composite blend known as polymer nano composites (PNCs). This study investigated the tensile response of polyester composites reinforced with petroleum-based carbon black (CB) nano particles. The composites were prepared with 1 to 11% volume fractions of carbon black nanoparticles using manual and machine dispersion methods. Tensile samples of 165 ×19.5 × 3.2 mm3 prepared using ASTM D638 Standard were tested in a Hounsfield (Monsato) testing unit. Results showed that tensile strength, percentage elongation and tensile toughness at fracture increased as the volume fractions of carbon black nanoparticles increased from 1% to 5% in both manual and machine prepared composites. It is important to note that the maximum tensile strength and percentage elongation at fracture occurred at 5% carbon black and as the volume fraction increased above this, tensile strength and elongation at fracture decreased. The machine mixed composite showed the highest improvement in the above tensile properties at this low volume fraction. The tensile modulus of manual mixed composite decreased as CB volume fraction increased. In contrast, modulus of machine mixed composite was constant from 1% to 5% but increased as volume fractions increased from 7% to 11%. The above findings corroborated earlier findings in previous works which noted that nanocomposites have advantage over micro composites at low volume fractions especially with better dispersion of nanopariculates in polymer matrices

Wettability Studies of Lead-Free Solders

Tin-Lead solder has been the standard joining material for use in electronic, chemical, automotive and other industries until various regulations around the world began to limit the use of lead due to its toxic effects. In this work, some lead – free solder alloys were produced and characterized for possible replacement of Tin-Lead solders. The solder alloys produced are: 91Sn–9Zn, 60Sn–40Zn, 42Sn–58Bi, and 90Sn–10Bi. Tin–lead solder alloy was also produced and subjected to the same wettability test with the other alloys under the same conditions for the purpose of comparing results. A characteristic of lead–free solders that greatly affects its solderability is its ability to wet the materials it joins. Based on this, a wettability test using copper grid was conducted on the solder alloys produced. The result shows that wetting time varied from 4 seconds to 5 seconds for the lead-free solders while it was 4.7 seconds for the Tin-Lead solder. Also wetting area ranged from 5.8% to 8.9% for the lead-free alloys and 8.3% for the lead containing solder. The respective contact angles in degrees for the lead-free solders varied from 580 - 730, while that for the lead solder was 570

Mechanical Properties of the Intercritically Annealed 0.15wt%C- 0.32 Wt%Mn Steel and Quenched in SAE Engine Oil at Room Temperature

Mechanical properties of the intercritically annealed 0.15wt%C - 0.32 wt% Mn steel and quenched in SAE engine oil at room temperature were investigated. The steel samples prepared for quenching and those prepared for quenching and then tempering were intercritically heat treated at 750, 760, 770, 780 and 790EC for 1hr in a laboratory muffle furnace and quenched to room temperature in SAE 40 engine oil. The steel samples prepared for quenching and then tempering were further subjected to a low temperature tempering at 150EC for 1 hr and air cooled to room temperature. The results revealed that strength and hardness values increased (from 512.29N/mm2 at 750EC to 674.62N/mm2 at 790ECfor strength and from 197BHN at 750ECto 241BHN at 790EC for hardness) with intercritical annealing temperatures but ductility and notch impact toughness decreased (from 12.18% at 750EC to 7.42% at 790EC for ductility and from 9.08 J/cm2 at 750EC to 5.55 J/cm2 at 790EC for notch impact toughness) with intercritical annealing temperatures. Tempered steel has yield strength values which increased with intercritical annealing temperatures from 180 N/mm2 at 750EC to 258 N/mm2 at 790EC. From the values it was observed that tempering gave rise to a decrease in tensile strength (from 674.62 N/mm2 at 790EC  to 637.65 N/mm2 at 790EC ) and hardness (from 241 BHN at 790EC  to 190 BHN at 790EC  ) and an increase in ductility ( from 7.97% at 750EC   to 12.18% at 750EC  ) and notch impact toughness (from 9.08 J/mm2 at 750EC  to 76.76 J/mm2 at 750EC ) of the as quenched steel. Tempered steels from the values presented better compromise between strength, hardness, ductility and notch impact toughness for automobile and other structural applications

Comparative Microstructural and Wettability Studies of 63sn-37pb And 58sn-42in Solders

The toxicity of lead during industrial production of components and the ecological damage caused by lead containing compounds has made the use of lead in solders undesirable. Hence, the emphasis of this research is to develop a solder that has unique material properties (like the conventional lead solder) using indium as a substitute to lead. Lead-bearing solder (63Sn-37Pb) and lead-free solder (58Sn-42In) alloys were developed and subjected to the same test analysis under the same test conditions so as to analyze and compare results. Both solders are low temperature alloys. The choice of any solder by industries depends on the ability of the solder to wet the materials it joins. Consequent upon this, a copper grid plate was used to conduct different wettability tests. The wetting time for lead bearing solder and lead-free solder are 4.7 and 5.9 seconds respectively while their corresponding contact angles in degrees are570 and 610. The final wettability test conducted was on the wetting area. The respective wettability values (in percentage) of the total area of the copper grid covered by the molten solder are: 8.3%, and 8.6% The alloy also have the following Vicker’s Hardness Values of 18.58VHN and 16.32VHN. The microstructures of the developed alloys were studied and analyzed. The alloy’s microstructures show that they are all eutectic compositions

Autonomous Renewable Energy Systems

This paper presents new ways of generating electricity from renewable energy sources and the development of the needed infrastructure for the next generation. The problems of having many renewable sources such as wind and solar generating units in a power system are uncontrollable fluctuations in power generation and the difficulty in forecasting the power generation capability of these sources due to their stochastic nature. Therefore, autonomous electricity systems with a high penetration of renewable energy sources are studied. A renewable energy laboratory DENlab is realized to analyse the autonomous application of renewable energy sources to a system of ten households (50 kVA). To have an opportunity to integrate other renewable sources with ease, a weak grid, grid-connected or a parallel operating situation can be created with small adaptations