MIG and TIG Joining of AA1070 Aluminium Sheets with Different Surface Preparations

In this work, AA1070 aluminium alloy sheets are joined using TIG and MIG welding after three different edge preparations. Shearing, water jet and plasma-cut processes were used to cut sheets, subsequently welded using ER5356 and ER4043 filler metals for TIG and MIG, respectively. Mechanical properties of the obtained sheets were assessed through tensile tests obtaining a relation between sheet preparation and welding tightness. Micro-hardness measures were performed to evaluate the effects of both welding and cutting processes on the micro-hardness of the alloy, highlighting that TIG welding gives rise to inhomogeneous micro-hardness behaviour. After tensile tests, surface fractures were observed employing scanning electron microscopy to highlight the relation between tensile properties and edge preparations. Fractures show severe oxidation in the water jet cut specimens, ductile fractures and gas porosities.

Production and Subsequent Forming of Chip-Based Aluminium Sheets Without Remelting

Bent components and deep drawn cups are produced by direct usage of aluminium chips without melting following a new process chain: hot extrusion of aluminium chips to a cylindrical open profile, flattening, subsequent rolling and bending or deep drawing. The properties of the hot extruded chip-based AA6060 sheets are examined by tensile tests and microstructural investigations and the results are compared with those obtained from material extruded from conventional cast billets. The chip-based sheets were used to form components by bending or deep drawing. No significant differences between the bent components or deep-drawn cups made of chips and those from cast material are observed regarding their capability for further plastic forming operations. This makes the new process route a resource-efficient alternative for the production of aluminium sheet products.

Electric performance of fastened hybrid busbars: An experimental and numerical study

This paper is focused on fastened hybrid busbars made from copper and aluminium with the purpose of analysing the influence of the steel bolts, of their tightening torque and of the surface condition of the sheets on the electric current flow and electric resistance of the joints. The methodology combines experimentation with unit cells that are representative of the joints and electro-mechanical numerical simulation using a finite element computer program developed by the authors. Results are a step forward in understanding the combined influence of bolts, contact pressure and surface roughness on the electric performance of fastened hybrid busbars. Design guidelines for dimensioning the cross sections of the copper and aluminium sheets and for effectively distributing bolts across the contacting surfaces are also provided.

Standardization of Homoeopathic Mother Tincture of Strychnous nux vomica with the help of High-Performance Thin Layer Chromatography and correlation of its alkaloid markers with its Toxicological action

Background: Chromatography is one of the important laboratory technique in which the components of a mixture are separated on an adsorbent in order to analyze, identify, purify and quantify a mixture. Thin Layer Chromatography (TLC)is used to support the identity of a compound in a mixture when the Rf of a compound is compared with the Rf of a known compound. High Performance Thin Layer Chromatography is a sophisticated and automated form of Thin Layer Chromatography (TLC). The procedure simultaneously processes the sample and standard that results in better analytical precision and accuracy at a faster pace. Pharmacological/ Toxicological action of Nux Vomica is because of its active principles present in the seeds namely strychnine, brucine etc. This research paper aims to corelate the active principles present in Nux Vomica with the toxicological action of the same. Materials and Methods: 1. Standard Nux Vomica mother tincture was tested for its alkaloid markers and its correlation with the toxicological action was studied. 2. Analysis of the mother tincture was done using High Performance Thin Layer Chromatography. 3. Stationary phase consisted of TLC Aluminium sheets with silica gel 60 F253 pre-coated layer (20cm x 10cm), thickness-0.2mm, no. of tracks-18, band length-6mm. 4. Mobile Phase consisted of Chloroform: Methanol (9.5:0.5). 5. The plate was developed in developing chamber and observed under U.V. Light. Results: Colours seen on the HPTLC Plates of samples are greenwhich corresponds to strychnine, dark blue which corresponds to brucine, orange to alkaloids fluorescent green to sterols and pink to fatty acids which are evident on the chromatogram. Conclusion: Therapeutic action of Nux Vomica as noted in Homoeopathic Materia Medica is because of the active principles like strychnine, brucine, alkaloids, sterols, fatty acids present in it which is evident from the chromatogram.

The Interaction between the Sheet/Tool Surface Texture and the Friction/Galling Behaviour on Aluminium Deep Drawing Operations

The increasing demands for lightweight design in the transport industry have led to an extensive use of lightweight materials such as aluminium alloys. The forming of aluminium sheets however presents significant challenges due to the low formability and the increased susceptibility to galling. The use of tailored workpieces and controlled die roughness surfaces are common strategies to improve the tribological behaviour, whilst galling is still not well understood. This work is aimed at analysing the interplay between the sheet and tool surface roughness on the friction and galling performance. Different degrees of Electro Discharge Texturing (EDT) textures were generated in AA1050 material strips, and tooling presenting different polishing degrees were prepared. Strip drawing tests were carried out to model the tribological condition and results were corroborated through cup drawing tests. A new galling severity index (GSI) is presented for a quick and quantitative determination of both galling occurrence and severity. The present study underlines the key role of die topography and the potential of die surface functionalization for galling prevention.

A Study on the variation of Apigenin content in Cardiospermum halicacabum from 21 districts of Tamil Nadu by HPTLC

Cardiospermum halicacabum is one of the most potent medicinal plants used in Indian traditional systems of medicine for the treatment of various diseases, mainly for arthritis. Apigenin is one of the major constituent present in Cardiospermum halicacabum. The present study mainly aimed to estimate the content of major constituent apigenin present in Cardiospermum halicacabum collected from 21 districts of Tamil Nadu by HPTLC method using the marker compound apigenin. The HPTLC method was performed using HPTLC aluminium sheets precoated with Silica Gel 60 GF254 as stationary phase and Toluene: Ethyl acetate: formic acid: methanol (3:6:1.6:0.4 v/v) as the mobile phase. The developed chromatogram was scanned at 254nm using Camag Scanner III. The Rf value of standard apigenin and apigenin in the leaf extract of Cardiospermum halicacabum was found to be in the range of 0.80 to 0.89. Plant collected from Cuddalore district of Tamil Nadu was found to contain relatively high amount of marker compound apigenin than other regions.

Effects of PCM thermal properties and thermodiode panel (TDP) on buildings' energy demand and indoor temperature

The performance of a thermodiode panel (TDP) is investigated thoroughly. A phase change material (PCM) layer is integrated into the TDP. A TDP can transfer solar thermal energy into the building. Adding a PCM layer to the TDP adds capacity of storing solar energy into the TDP, and releases the stored energy when the sun goes down. The TDP is composed of dense foam, which is sandwiched between two aluminium sheets, and a thermosyphon passes through the foam layer. PCM layer is added to the condenser section of the TDP that is connected into the building envelope. PCM thermal properties and their effects on energy demand and indoor temperature are investigated on a typical building. The best melting point for the PCM was found to be a temperature in the middle of the set points (upper and lower). Quantitative indices are introduced to evaluate the effects of PCM on indoor air temperature fluctuations. PCM reduces the indoor air temperature fluctuations. Increasing thermal conductivity of PCM by an order of magnitude reduces about 2% annual energy demand of a building. Regarding convention heat transfer coefficient, by increasing the convective heat transfer coefficient at interior wall surface, the cooling demand slightly increases in summer. In winter, energy demand is sensitive to h-value with a positive correlation. Matlab codes developed using genetic algorithm to optimize the TDP sizes, i.e., thicknesses of three aluminium sheets, copper tube diameter and its thickness that makes the structure of thermosyphon. The optimum sizes found to be: plate thicknesses of 1.5 mm, 2.5 mm, and 2 mm and thermosyphon diameter and thickness of 32 mm and 9 mm, respectively, provide the maximum objective function (the best performance of the TDP). Thermal bridging of a TDP can be reduced 76 times by adding a piece of Teflon in the thermosyphon assembly. The integration can do both store and collect/gain solar thermal energy, which makes this panel a novel alternative for south walls. It is also shown that thermosyphon angle from the horizon shall be between 30 and 45 degree to have the best performance of the TDP.