New Advances in Materials Science and Engineering Vol. 2

Advancement of Oxide Bonded Porous SiC Ceramics

Dulal Das — 2020-01-16

Silicon carbide is an important non-oxide ceramic material used in wide range of industrial applications due to its exclusive properties such as high hardness and strength, chemical and thermal stability, high melting point, oxidation resistance, high erosion resistance, etc. All of these qualities make SiC a perfect candidate for various applications. A variety of processing techniques are tried to develop porous SiC ceramics starting from traditional Acheson method, which led largely into commercialization of silicon carbide. The fabrication of porous SiC ceramics by an oxidation bonding technique offers several advantages like good oxidation resistance because of air sintering of the ceramics, low sintering temperature, cost effectiveness and easy control over the porosity and other properties of the resultant ceramics. In this chapter, a brief summary is given on the effect of pore former, powder size, sintering temperature and sintering additives on the properties of the oxide bonded porous SiC ceramics with emphasis on mechanical properties, thermal shock resistance properties, gas permeability behavior and separation of particulate from off gas. This chapter has also enlightened the present use of oxide bonded porous SiC ceramics and discussed about the possible future scope in other application areas.

Controlled Oxidation of a Tetrafunctional Thiol to Obtain a Poly (Thiol- disulfide) Oligomer and Its Use as Self-healing Agent for Epoxy/Thiol-ene Photocurable Systems

Ricardo Acosta Ortiz — 2020-01-16

In this work the pentaerythritol tetrakis (3-mercaptopropionate) was partially oxidized to obtain an oligomer with both thiol and disulfide functional groups in its structure, by using iodobenzene diacetate (IBDA) as oxidant. This oligomer was used to introduce disulfide bonds into the crosslinked network of a polyether-polythioether matrix obtained by photopolymerizing an epoxy/thiol-ene system. The presence of the disulfide bonds induced self-healing properties bonds in the obtained co-network. The oligomer was a joint component of the thiol-ene system along with a tetraallyl-functionalized ditertiary amine curing agent and a radical photoinitiator. The thiol groups of the oligomer reacted with the double bonds of the curing agent to form polythioethers, while the tertiary amine groups of the curing agent induced the anionic ring opening polymerization of the oxirane groups of an epoxy resin to produce polyethers. The kinetics of photopolymerization of the epoxy resin diglycidylether of bisphenol A (DGEBA), revealed that conversions of the epoxy groups as high as 80 % were achieved in only fifteen minutes by increasing the concentration of the thiol-ene system in the formulation. The disulfide bonds introduced in the co-network by using the thiol-disulfide oligomer, allowed the repairing of the test specimens in as little as 10 minutes when the specimens were heated at 80 °C or for 500 minutes at room temperature. The analysis of mechanical properties using dynamic mechanical analysis (DMA) showed that the healed specimens, retained their mechanical properties depending on the amount of polythioethers present in the co-network.

Optimization of Packaging Line Performance: A Case Study of AB Breweries in Nigeria

Chinedu James Ujam — 2020-01-16

This paper presents an approach for improving productivity in breweries. A case study of AB brewery was adopted. Traditionally, packaging line improve performance and productivity based on extrapolation of past experience, but in recent times, the traditional method could not meet up with high increase in demand of products, hence the need to adopt a new approach of using information technology and software to analyze problems and improving performance. Eleven weeks of the following data were collected and calculated; production outputs and running time; OPI and Target; and Packaging line downtimes. Downtimes were grouped into machine breakdown, planned downtime and external downtimes and analyzed with histogram to know the impact of each group to the overall downtimes. To apply fishbone diagram, it was further grouped into Material, Method, Man and Machine after which a Pareto graph was plotted to understand the area of focus in tackling production system problems. Tecnomatrix plant simulation software was adopted to develop a simulation model that mimic the real system which further found hidden problems existing within the production system. Design of experiment was carried out to select the best alternatives from the results generated, and finally excel spreadsheet interface was developed for better analysis and performance tracking of optimized system. Result of data analysis indicated that machine breakdown and external downtimes were the major problems affecting performance, while simulation model revealed that unregulated system and un-optimized regulated lines recorded high machine breakdown and speed losses which affected the production performance output respectively. Design of experiment found the best speed combination of sensors to optimize two labellers.

Advanced Thermal Barrier Coatings

Sumana Ghosh — 2020-01-16

Yttria Stabilised Zirconia (YSZ) is a conventionally used top coat material for a thermal barrier coating (TBC) system below 1200°C. However, YSZ is not suitable as top coat above 1200°C on account of its sintering effect. Advanced coatings have been developed by the researchers, which would satisfy the need for the mechanical and the thermal properties of the TBCs. The current chapter covers advanced thermal barrier coatings that are suitable for the future generation gas turbines.

Polymer Based Nanocomposites for Power Engineering Applications

Anupa Nandi — 2020-01-16

Polymer nanocomposites is a combination of polymer matrix and with a wide range of 1-D, 2-D or 3-D filler materials (organic and inorganic) having at least one dimension in nm range. Polymer nanocomposites have unique structures, morphology as well as mechanical, thermal and electrical properties. Therefore, study on polymer nanocomposites are being continued for about 25 years. The transition from micro- to nano- particles lead to change in its physical as well as chemical properties. Carbonaceous nano fillers such as graphene, CNTs play a very promising role due to their better structural and functional properties such as high aspect ratio, high mechanical strength, high electrical properties etc. Several researchers have been able to successfully implement graphene or hybrid filler based polymer nanocomposites in electrochemical applications, lithium ion batteries, sensors, solar cell, water purification, supercapacitors, drug delivery and tissue engineering. Nanotechnology has the potential to create many new materials and devices with wide-ranging applications, such as in medicine, electronics, and energy production.

Reprocessing Leading to Lower Thermal Conductivity of ZnO Thermoelectrics

D. S. Tucker — 2020-01-16

Nanometer sized ZnO powder was co-doped with gamma aluminum oxide and gallium oxide and sintered using a direct current sintering furnace. Sintered samples were reprocessed by crushing the samples in a Carver press, then milling for 4 hours. The reprocessed samples were then re-sintered in the direct current sintering furnace. Heat capacity, density and thermal diffusivity were measured in order to determine thermal conductivity as a function of temperature. Thermoelectric properties were measured. It was found that the thermal conductivity decreased from 7 W/m K to 3.5 W/m K at 805K by using the reprocessing technique. It is projected that the value will be less than 2 W/m K and the figure of merit greater than 0.65 at 1400K.

Prediction of Onset of Mode I Delamination Growth under a Tensile Spectrum Load

J. Raju — 2020-01-16

In this investigation, the onset of mode I delamination growth under a standard aircraft spectrum load sequence, mini-FALSTAFF truncated to contain only tension-tension fatigue cycles is predicted. The study was carried out on a standard Double Cantilever Beam (DCB) test specimen of Uni Directional (UD) layup Carbon Fiber Composite (CFC) IMA/M21. Finite element modeling and analysis was carried out using ABAQUS standard to determine Strain Energy Release Rate (SERR) by Virtual Crack Closure Technique (VCCT). Both two dimensional (2D) and three dimensional (3D) models were studied. Using the FE analysis results, an empirical equation was derived for SERR (G) and load (P) relationship. Further, the load cycles in the spectrum sequence were rain flow counted to separate individual cycles. For each of the counted cycle, the SERR was obtained and corresponding N _onset for that cycle was estimated from the Constant Onset Life Diagram (COLD) of the material. Linear damage accumulation law was used to predict the number of spectrum load blocks required for onset of mode I delamination growth. The prediction was carried out for various reference loads (P _ref) and the corresponding reference SERR (G _ref) of the spectrum sequence. Predicted results show that decreasing the reference stress increases the mode I delamination onset life under spectrum loads.

AC Conductivity Characteristics of Polymer/Metal Oxide Thin Films

A. R. Bansod — 2020-01-16

Organic/inorganic polymer composite films containing poly (methyl-methacrylate) (PMMA)/ ferric oxide Fe₂O₃ were prepared following solution casting technique. Dielectric Properties of films has been studied using LCR meter at room temperature 26ºC. Also optical properties have been studied using digital abbey refractometer. The dielectric behavior of films have been studied as a function of concentration, and at lower frequencies over the range 100 Hz-25 KHz. The results elucidate that 70:30 and 50:50 wt% of PMMA/Fe₂O₃ composite films posses optimal conducting properties due to observed electronic polarisability dip at 40Wt% of Fe₂O₃.

The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures Using (1) Cu Kα Data and (2) Synchrotron Data

Mohamed A. Makhyoun — 2020-01-16

C₁₂H₂₀N₆NiO₆S₂ or NiL₂(SCN)₂](NH₄)₂.2H₂O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermo-gravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C₁₂ H₂₀ N₆ Ni O₆ S₂], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P2₁/n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.

Effect of Solvent on Catalysis of Protease Adsorbed on Biochar in Organic Media

Hidetaka Noritomi — 2020-01-16

The adsorption immobilization of the serine protease α-chymotrypsin (α-CT) onto bamboo charcoal powder (BCP), which is a kind of biochar, improved the transesterification rate of N-acetyl-L-tyrosine ethyl ester (N-Ac-Tyr-OEt) with n-butanol (BuOH) in 9 organic solvents. Organic solvents strongly affected the catalysis of BCP-adsorbed α-CT. The transesterification rate of BCP-adsorbed α-CT was much superior to that of free α-CT in every organic solvent. Especially, the transesterification rate of BCP-adsorbed α-CT was about 760 times higher than that of free α-CT in n-butyl acetate.

Thermal Stabilization of HEWL by Adsorption on Biochar

Hidetaka Noritomi — 2020-01-16

The heat stress tolerance of hen egg white lysozyme (HEWL) was markedly enhanced by the adsorption of HEWL on bamboo charcoal powder (BCP), which is a kind of biochar. HEWL was firmly adsorbed on BCP even at high temperatures. The secondary structure of HEWL was altered to some extent by the adsorption of HEWL on BCP. The remaining activity of BCP-adsorbed HEWL exhibited more than 20% after the incubation for 30 min at 90°C although that of free one was hardly observed. Moreover, the half-life of BCP-adsorbed HEWL was 13 min at 90°C while that of free one was 4 min.