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Aluminium alloys are one of the choice materials with ever-increasing demands in manufacturing industries. The aluminium alloy 6 xx series such as AA6061-T6, has emerged as one of the promising materials utilized owing to its combination of favourable properties which include high strength to weight ratio, good ductility, excellent corrosion resistance and relatively low cost. These superior properties are responsible for its emergence and usage in the fabrication of aircraft wings and fuselages, yacht/ship construction, automotive rims and wheel spacers. However, joining of AA6061-T6 including the use of friction stir welding (FSW) has serious concerns because the mechanical and tribological properties of the AA6061-T6 welded joints deteriorate significantly compared with the base metal. This phenomenon has been attributed to the severe softening encountered at the stir zone (SZ) of the aluminium matrix during FSW. Other inherent challenges of FSW such as weld thinning, kissing bond and keyhole formation also contribute to the reduction in the weld joint quality. The softening phenomenon has been linked to the dissolution of the strengthening precipitates (B″-Mg5Si6) as a result of high heat input during the welding process. Hence, this paper attempts to review the various improvement strategies adopted in the existing studies to improve the quality of AA 6061-T6 welded joint. These include parametric optimization, selection of appropriate tool design, pre and post heat treatments, adoption of different groove/hole designs for particle addition as well as the addition of reinforcement particles to the weld joint. The variants of FSW recently developed will also be considered. The findings from the review will generally be useful for future work on FSW of heat treated aluminium alloys. The evolution of FSW and its associated challenges are briefly discussed while the research areas yet to be harnessed are suggested for future works.

The techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultramicrotomy and energy dispersive X-ray analysis (EDX) were employed to examine conversion coatings on aluminium developed from a zirconium nitrate/fluoride solution. The coating developed slowly on a microscopic metal substrate with islands of zirconium-rich centres within the coating matrix. According to the TEM assessment, the coating thickness was 30 nm for specimens treated for 60 s and 50 nm for those treated for 900 s. The population of the zirconium-rich centers ranged from 2.8 × 1012 m–2 to 6 × 1012 m–2 over the treatment period. According to Auger-electron-spectroscopy in-depth analyses, the coating is composed of three diffused layers with an outer region of zirconium oxide followed by a layer of aluminium oxide/hydroxide and an inner layer at the metal/coating interface comprising compounds of aluminium and fluorides. The corrosion-resistance and paint-adhesion characteristics of the zirconium conversion coating are superior to those of bare aluminium.

Modified chicken feather reduced the corrosion rate of mild steel in drilling mud as deduced from electrochemical potentiodynamic polarization technique, albeit, with observed infestation of the test environment by microbes over protracted exposure period of 92 days. The corrosion rates with and without the addition of 0.3g of hydrolyzed feather per 100 ml of drilling mud were 1.70 and 1.95 mm/yr, respectively; which corresponded to inhibition efficiency of 13% over the immersion period. The corresponding charge transfer resistances, a measure of corrosion rates were 1480.4 and 1780.0 Ω, respectively; in the uninhibited and hydrolyzed-feather inhibited environments. The voltage over the double layer capacitor as obtained from the polarization studies numerically increased from −0.907 to −0.948 V which indicated adsorption of moieties in the inhibitor and probably some corrosion products on the surface of the mild steel specimen. Keywords: Valorized chicken feather, Corrosion, Inhibitor, Polarization, FTIR

This investigation on permanganate-based conversion coating describes a chromate-free coating and efforts at reducing the environmental foot prints of metal finishing industries. A golden coloured coating on aluminium specimen was obtained from the permanganate coating (PMC) bath with nominal pH of 7.9. Results from scanning electron microscopy (SEM) examination showed that the conversion coatings are continuous, and the surfaces of the specimens treated in the coating bath are composed of irregularly shaped and mud-cracked coating materials. The coatings, as revealed from energy dispersive spectroscopy (EDX) analyses in the SEM are composed essentially of aluminium, oxygen and manganese compounds which are likely to be hydrated. Accelerated corrosion tests in near neutral 3.5% sodium chloride solution and natural exposure tests revealed that the replacement of chromate with permanganate improved paint adhesion and corrosion resistance on aluminium substrates. Furthermore, the results indicated that the corrosion resistance of the permanganate-based conversion coating matched those from the traditional chromate coating bath, but for the corrosion resistance, after application of a top coat of lacquer, the former was adjudged better than the later. Keywords: Aluminium, permanganate, corrosion resistance, conversion coating, corrosion

Petroleum and petroleum products are expensive commodities due to their global demand as a major source of energy. As a result of its expensiveness, there is need for proper inventory to know what is going in and coming out of the storage tanks. Proper inventory is achieved by accurate measurement through the generation of a calibration chart for every storage tank. Calibration chart (tank table) gives the needed information about the level (height) and the corresponding volume of the petroleum product in the storage tank. Geometrical method (dry calibration) is the most widely used method of computing tank table using the field data such as circumference, shell or plate thickness, length of barrel and lap/butt strap while taking the necessary correction factors into consideration. Microsoft Excel is a powerful tool in Microsoft (MS) office package used for computation and programming through the use of visual basic for application. In this study, MS Excel was used to generate two different charts which were compared with the charts generated from customized specialized calibration software from Societe Generale de Surveillance (SGS software) and the results were found to be within the statistical controlled limit.

The solder joints of ball grid array utilized in consumer electronics systems or assemblies degrade and fail overtime. Their degree of degradation is more critical, especially at elevated temperatures and mechanical loading conditions. This study presents the effect of component standoff height (CSH) on the shear strength reliability of ball grid array solder joints under different pad sizes. Investigation of the impact of standoff height on the mechanical reliability of the solder joint of ball grid array components under different pad sizes was conducted in this work. Isothermal ageing of test samples were conducted at 150 °C for 8 days. This study focuses on establishing the relationship between CSH and shear strength of the solder joints under different pad sizes and the corresponding effect of prolonged elevated temperature conditions on the mechanical integrity of the soldered joints. The work also identifies the failure mode and examines the region of the failed joints and surfaces to provide information on the morphological characteristics of the material microstructure. The results of this study demonstrate that the smallest pad size (19 mil) gave the lowest shear strength of 61.08 MPa with a high standoff height of 0.25 mm as compared to the largest pad size (24 mil) with the highest shear strength of 70.43 MPa having a relatively low standoff height of 0.22 mm.

Concretes are composite materials which decay as a result of steel corrosion in concrete structures is mostly accelerated in environments laden with chlorides and industrial effluent gases as well as harsh chemicals employed in and those generated from wastes in agricultural industries. This review summarises the effects of various environmental pollutants which promote deterioration of concretes with resultant corrosion of reinforcing bar (rebar). An overview of traditional and current methods for significant reduction of this mode of material deterioration is described. Discussions on management tools for rebar corrosion in agricultural and marine environments have been highlighted. Repair methods include the traditional application of patch repair mortar which has been modified with polymeric materials to improve adhesion and reduce porosity. The use of cathodic protection system to reduce rebar corrosion to its barest minimum has gained currency. Attention should be directed at corrosion reduction practices at the design and planning stages as well as modification concrete mixes with modified agricultural wastes/products and polymers.

Conversion coating on aluminium/0.2%Fe alloy developed from a zirconium nitrate/fluoride solution has been examined with scanning electron (SEM) and transmission electron microscopes (TEM) with attached energy dispersive X-ray (EDX) facilities. Zirconium-rich islands of thicker sections were observed in the SEM. The thin sections from the transmission micrographs revealed undulating metal/coating and coating/solution interfaces. This is consistent with anode/cathode reactions in the formation and growth of conversion coatings on metals, especially aluminium alloys. The coating comprises of zirconium rich surface which is contaminated or otherwise with aluminium and other species from the coating solution.

Several wastes can be instrumental in the improvement of the mechanical properties of medium carbon steel when quenched. The quenching media employed such as coconut water (CW), pap water (PW) and spent engine oil (SPE) have been largely considered as wastes. The data in this article are related to the research article titled “Mechanical Properties Improvement Evaluation of Medium Carbon Steels Quenched in Different Media” (Ikubanni et al., 2017) [1]. The article provides information on the mechanical properties evaluation of medium carbon steel quenched in different media. Twenty-seven (27) samples of medium carbon steel samples were heated to temperatures of 730 °C, 760 °C and 790 °C and soaked for 30, 45 and 60 min respectively. The test results recorded include hardness value, yield strength (YS) and the ultimate tensile strength (UTS) for each of the samples at different heating temperatures and soaking time for the different quenching media. Keywords: Mechanical, Tensile strength, Yield strength, Quenching media, Hardness value, Properties