பொருள் அறிவியல் & பொறியியல் இதழ்

This study deals with the environment and different liquid environments which have effect on both the colour fastness and the mechanical properties – which can be expressed as tensile strength and elongation – of coloured high density polyethylene polymer in net form, used for warning and used as an indicator for the undo ground pipes passage. It was found that withering affects shows that the tensile strength and the elongation considerably, while change on temperature of the surroundings was found to show less effect. Also, environment liquids caused a small loss in tensile strength of about (6%) while the samples in extended percent or about (22%) was observed. Both parameters were showed an appreciable change at damped soiling mud. The light fastness of the examined polymer samples were greatly affected by weathering conditions, while the other factors did not affect the light fastness considerably.

Carbon fibers were employed to reinforce the modified epoxy resins by flexibilizer to enhance the overall. mechanical properties, the tensile strength, modulus, impact strength, fracture toughness test at both 77 K and at room temperature were examined for carbon fiber reinforced composites. At last section finite element simulation by ANSYS-13 was analyzed for crack propagation analysis of unidirectional laminates used for experimental by two methods-(a) Double cantilever beam (b) Single edge notch bending (J-Integral).

Tungsten Inert Gas (TIG) welding process is generally used for welding of aluminum alloys. TIG process is generally preferred because it produces a very high quality weld. Distortion is the major problem in welding of thin sections. This distortion is controlled in pulsed and magnetic arc oscillation TIG process. The metallurgical advantages of pulsed TIG welding are grain refinement in fusion zone, reduced width of HAZ, less distortion, control of segregation, reduced hot sensitivity and residual stresses. It was observed that pulsed TIG welding produces finer grain structure of weld metal than conventional TIG welding (without arc pulsation). The mechanical properties (Hardness) and microstructure characteristic of weld metal depends upon the microstructure of the weld. The microstructure of the weld depends upon pulsed parameters peck current, base current, pulse frequency, pulse duration. The objective of present project is to achieve better mechanical properties. So, controlling of pulsed parameter is needed in this investigation. An increase in the pulse frequency has been found to refine the grain structure of weld metal especially when welding is done using short pulse duration. Long pulse duration lowers the pulse frequency up to which refinement of constituents in weld metal takes place. Effect of the pulse frequency on the grain structure was found to be determined by pulse duration. For a given pulse frequency, long pulse duration produced a coarser structure than short pulse duration. An increase in the peak current coarsened the grain structure.

Boron nitride (BN) is known for high hardness, thermal stability, thermal conductivity, and catalytic action. The aim of this study was to investigate the effect of biofield treatment on physical, structural and spectral properties of BN powder. The control and treated sample of BN powder were characterized by X-ray diffraction (XRD), surface area analysis and Fourier transform infrared spectroscopy (FT-IR). XRD results indicated that biofield treatment had substantially changed the crystallinity of BN powder as compared to control. Apart from the crystallinity, significant changes were also observed in lattice parameter, density and molecular weight of the treated BN powder as compared to control sample. The XRD data confirmed 33.30% increase crystallite size in treated BN powder as compared to control. The surface area data showed 10.33% increment in surface area of treated BN as compared to control. Furthermore, FT-IR spectra revealed that some part of BN may be transformed from hexagonal BN (h-BN) to rhombohedral boron nitride (r-BN), which was corroborated by emergence of new prominent peaks at 1388 cm-1 in treated BN as compared to control sample. These findings suggest that biofield treatment has substantially altered the structural properties and surface area of treated BN powder.

AgSiO2, ZnAg and Ag-Zeolite were investigated for antimicrobial activity using Gram-negative Pseudomonas aeruginosa, Shewanella putrefaciens and Gram-positive Clostridium, Listeria monocytogens as target microorganisms by disk diffusion and Agar plate MIC method. These bacteria are responsible for microbiological and chemical spoilage of sea food mainly and from the result we found that Silver zeolite, AgSiO2 has good antimicrobial activity for all target microorganisms except for clostridium perfringem. ZnAg has also shown good antimicrobial properties against all target microorganisms except Listeria monocytogens. Only ZnAg is capable to reduce clostridium perfringem as compare to Silver zeolite and AgSiO2.

The efficiency of laser transmission welding strongly depends on the optical properties of the plastic parts to be joined and the process parameters. This paper investigates the effect of the laser welding parameters such as laser power, welding speed on weld strength. A 200 W YAG laser with wavelength 1064 nm has been used to weld transparent and absorbing polycarbonate (PC) in lap weld configuration. The force at break of the lap welds was assessed on the Universal testing machine, weld fracture surfaces and weld cross-sections were also analyzed under microscope using reflected polarized light to qualitatively assess the weld quality.

A novel scheme for implementation of all-optical logic gate based on 2D photonic crystal structure has been proposed. The design and simulation of novel all-optical logic gates based on two dimensional photonic crystals are reported in this paper. The proposed PCS is comprised of two-dimensional lattice of air holes in a square Silicon substrate having refractive index of 3.15. The operational wavelength of the input ports is 1.55 μm. Since the structure is a simple geometric in its dimension with clear operating principle, it is potentially applicable for photonic integrated circuits. The logic operations are realized by a control signal and the input signal (s) applied across two adjacent faces, while the output is obtained along one of the remaining face. No control signal is used for AND Gate, However to realize OR, NOT and NOR Gates a control signal is applied at the third face. With same structure one can realize all optic logic gates. The steady state field distributions at different input sates are obtained by FDTD simulation. The results indicate the potential candidature of the photonic crystal for optical digital integrated circuits.

In Mn3O4, the crystal structure, dislocation density, particle size and spin of the electrons plays crucial role in modulating its magnetic properties. Present study investigates impact of Biofield treatment on physical and atomic properties of Mn3O4. X-ray diffraction revealed the significant effect of biofield on lattice parameter, unit cell volume, molecular weight, crystallite sizes and densities of treated Mn3O4. XRD analysis confirmed that crystallinity was enhanced and dislocation density was effectively reduced by 80%. FTIR spectroscopic analysis revealed that Mn-O bond strength was significantly altered by biofield treatment. Electronic spin resonance analysis showed higher g-factor of electron in treated Mn3O4 as compared to control, along with altered spin-spin atomic interaction of Mn with other mixed valance states. Additionally, ESR study affirmed higher magnetization behaviour of the treated Mn3O4. The results demonstrated that treated Mn3O4 ceramic could be used as an excellent material for fabrication of novel magnetic data storage devices.

Composites with aluminium alloy matrix and ceramic reinforcements are popular candidates in automotive, aerospace, defense and other industries because of their high strength-toweight ratio, stiffness, impact strength, wear resistance, etc. In the present study AA 5083/Nano SiC composite were fabricated by stir casting. A 2-level Full Factorial design of experiments (DOE) was used to study the influence of process parameters like casting temperature, stirrer speed, and weight percent of reinforcement on hardness of composites. Mathematical model was developed to investigate which parameters significantly affect the hardness of composites. The effect of parameters on the response and adequacy of hardness model developed were tested by employing ANOVA and Fisher’s F-test. This model can be used to select the optimum process parameters for obtaining the composites hardness within the range of experimental frame work.

We know different casting processes like sand casting, gravity die casting, low pressure die casting, pressure die casting, counter pressure die casting, and centrifugal casting, spin casting, lost wax and lost foam casting. But lost wax or lost foam casting process are going to be most acceptable way of castings to get the intricate and complex shaped castings. Lost wax process is generally known as “Investment casting process”. About 5000 years ago the Egyptians used this process in the time of Pharaohs to make gold jewellery, which was the way of their investment hence the names comes. Ancient “lost wax process” domination for producing beautiful sculptures turns into a present day near net shape manufacturing of intricate engineering components. The journey begins with the development of Investment casting process by Dr. William H. Taggart of Chicago who wrote a detailed study on Investment casting process in 1907. Today’s Investment casting is a versatile process. It is used to manufacture parts ranging from turbocharger wheels to golf stick heads, from electronic boxes to hip replacement implants, General engineering to aerospace, automobiles to pump industries particularly impellers. In this paper we are discussing about the key parameters of the investment casting process which will give a more dimensional accuracy and best surface smoothness and hardness for the mold. The pre-conditions for the mold are discussed and possible defects can occur in the mold and the rectification also analysed experimentally.

Shear extrusion is a forming process which is based on combined backward cup-forward rod extrusion. This extrusion process is attractive due its potential to achieve severe plastic deformation thus enabling texture and microstructural control of materials. Furthermore, the economic potential of shear extrusion for mass production and production of complex shapes provides for numerous applications in automotive, transportation, aero-space and other industries. However, a trending challenge in the use of this method for complex shapes is the design and selection of tools to achieve a high quality product. This paper focuses on deep study of shear extrusion of AA-6063. The process was studied experimentally using variables which affect the forming load as well as the quality of the product. It is concluded from the load-displacement and stress plots that a punch with large diameter and small punch land is desirable for easy forming of the material during shear extrusion. Analysis of the effect of lubricants on deformation load and stress shows that palm oil lubricant remains the best lubricant of the four lubricants examined since its gives the minimum load obtained during shear extrusion.

Substantial progress on developing fiber reinforced cement-based composites has been made recently. Fiber Cement Sheets (FCS) are particularly suitable for the use behind tiling in wet areas, considerable use as backer boards for counter tops, wet area internal lining boards. The present work investigates the pultrusion of a jute fabrics reinforced by Polymeric matrix material (Concresive 1315 M) which has excellent resistance to most aqueous substances and liquids, including sea water, brackish water, effluent and raw sewage, acids of low concentration, alkalis, oils (mineral and organic), thus protects the jute fabrics improving durability of fiber cement sheets (FCS). Enhance the adhesion between the natural fibers and cementation composite results in the improving of composite’s strength and toughness as well as the flexure strength and bending stiffness. In this study, the influence of a fabric treatment of the textiles to reinforce cement materials as well as fabric structure and the resin properties has been investigated. For the hybrid jute fabric reinforced cementitious composites, the integrated performance, mechanical properties, particularly bending stiffness and cracking response, were evidently influenced by the fabric structure and the resin properties. The mechanical properties were evaluated by performing 4-points bending as well as tensile tests. Pultrusion jute reinforced Polymeric matrix material increases the tensile strength, Modulus of elasticity, and the Modulus of rigidity and reduces the breaking elongation. Flexural strength of fiber cement sheets (FCS) has been significantly improved using pultrusion of the Jute/Polymeric Matrix Fabric. It is observed that bonding between cement and jute fabric after pultrusion is excellent and no sign of delamination is noted. These changes in the fabric properties made it more suitable to be used in the production of the cementitious thin sheets.