Synthesis, physico‑mechanical and microstructural characterization ofAl6063/SiC/ PKSA hybrid reinforced composites

The utilization of agro-residues ash as complementary reinforcing materials continues to gain prominence for metal matrix composite (MMCs) development. A rarely investigated but largely available ash among these agro-residues is the palm kernel shell ash (PKSA). Thus, the present study investigates the influence of PKSA particulates hybridized with SiC on the physico-mechanical properties and microstructure of Al6063 metal composites. The composites are synthesized using the double stir-casting technique with SiC held constant at 2 wt.%, while the PKSA contents are varied from 0 to 8 wt.%. The phases present and morphology of the composites are investigated using X-ray diffractometer (XRD) and scanning electron microscopy (SEM), respectively. The density, porosity, hardness, tensile and fracture toughness tests are carried out on the hybrid composites. X-ray diffractometer revealed that for Al 6063, only Al cubic crystal system was identifiable within the matrix. However, for the reinforced composites, major phases identified are Al, Fe(3)Si, SiC, MgO, and SiO(2). The SEM images show that the particulates reinforcements (SiC and PKSA) were uniformly dispersed in the matrix. The percentage porosity for the composites ranged from 2.06 to 2.39%. In addition, hardness, yield strength and ultimate tensile strength of the composites are about 10.3%, 18.5% and 10.4%, respectively better than for Al 6063. However, the percent elongation and fracture toughness are lower for the hybrid composites than for Al 6063 and SiC reinforced composite with values decreasing with increase in ash content. Hence, the MMCs produced will be applicable for light-weight engineering applications

Electrochemical Studies of the Corrosion Behavior of Al/SiC/PKSA Hybrid Composites in 3.5% NaCl Solution

The corrosion behavior of metal matrix composites (MMCs) is accelerated by the inclusion of reinforcements. Hence, this study investigates the corrosion behavior of MMCs produced from Al 6063 matrix alloy with reinforcement particulates of silicon carbide (SiC) and palm kernel shell ash (PKSA) inclusion at different mix ratios. The MMCs were synthesized using the double stir casting technique. The corrosion behaviors of the composites in NaCl solutions were studied via gravimetric analysis and electrochemical measurements. The gravimetric analysis showed fluctuating dissolution rate of the samples in NaCl solution to indicate flawed film as well as corrosion product formation over the surface of the specimens. The observed corrosion mechanism of the samples was general and pitting corrosion. The presence of reinforcements within the Al6063 matrix acted as active sites for corrosion initiation. The range of values for Ecorr and Icorr obtained in 3.5% NaCl at 24 h was between −220.62 and −899.46 mV and between 5.45 and 40.87 µA/cm2, respectively, while at 72 h, the Ecorr values ranged from 255.88 to −887.28 mV, and the Icorr ranged from 7.19 to 16.85 µA/cm2. The Nyquist and Bode plots revealed the electrochemical corrosion behavior of the samples under investigation, with predominant reactions on the surface of the samples linked to charge transfer processes. The relative resistance to corrosion of the samples depends on the thin oxide film formed on the surface of the samples

Influence of temperature on the chemical compositions and microstructural changes of ash formed from palm kernel shell

This study investigated the characteristics of raw palm kernel shell (raw PKS) and the influence of temperature variation on palm kernel shell ash (PKSA). The PKSA was obtained under different temperature regimes of 900, 1000, and 1100�C. The characterization of the samples was carried out using X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with attached Energy Dispersive X-ray (EDX) facilities. The results showed that moisture and ash contents and the density of raw PKS were 6.56%, 8.86%, and 745 kg/m3 , respectively. The colour of the pulverized PKS was dark brown, as observed by visual examination based on standard colour gradation. This colour transformed into various shades of brown when PKS was subjected to different temperature regimes to form PKSA. The XRF analysis showed that silica is the main constituent of the raw PKS and PKSA samples. Silica content in the PKSA increased with the rise in the heating temperature. The FTIR and EDX spectra confirmed the predominance of silicon compounds with functional groups associated with silanol and siloxane. Also, XRD analysis revealed that the silica contents in the samples are quartz, while SEM examinations indicated that temperature increases during processing influenced the microstructure through the reduction of pore concentration in the samples. The silica obtained from the PKSA would find applications in metal matrix composites as partial reinforcing material

INVESTIGATIVE STUDY OF THE EFFECTS OF CERTAIN ADDITIVES ON SOME SELECTED REFRACTORY PROPERTIES OF ANT-HILL CLAY FOR FURNACE LINING

The choice of appropriate locally sourced refractory materials for lining of locally produced furnaces has remained a major concern in which numerous efforts has been put in place to enhance the performance of the local contents of furnace lining materials. This study investigates the effects of certain additives such as Pulverized Glass Wastes (PGW) and Bentonite on some selected refractory properties of ant-hill clay. 100% finely-ground ant-hill clay, clean water and proportionate amount of Bentonite and PGW were manually mixed, consolidated and oven-dried at 110 oC for a period of 8 hours at varying additives percentages. Compressive strength, apparent porosity, permeability, filtration rate, thermal conductivity and bulk density were experimentally determined... The results showed that the compressive strength, bulk density and thermal conductivity of Ant-hill clay increased significantly on addition of additives while there was corresponding decrease in the values of the filtration rate, apparent porosity and permeability. These values were enhanced by Bentonite and pulverised glass waste additions to the Ant-hill clay. The test results for the compressive strength, thermal conductivity, filtration rate, apparent porosity, bulk density and permeability of no-additive clay samples are 156.4 N/m2 , 0.0028 W/m2K, 0.0041cm3 /s, 0.0009 %, 6.3 g/cm3 and 0.0012 cm/s, respectively. However, the sample-mix consisting 100% ant-hill clay with 80% PGW and 20% Bentonite produced 333.4 N/m2 , 0.0032 W/m2K, 0.0037 cm3 /s, 0.00018 %, 9.5 g/cm3 and 0.0015 cm/s as optimum values for the compressive strength, thermal conductivity, filtration rate, apparent porosity, bulk density and permeability, respectively. Therefore, 80%PGW/20%Bentonite additives gave the optimum results for the production of refractory clay blocks for furnace linin

Performance of Tannin/Glycerol-Chromate Hybrid Conversion Coating on Aluminium

A smart hybrid conversion coating has been developed. Modifications of coating solutions with poly-hydroxyl organic materials to reduce the usual mud cracking pattern characteristics of chromate conversion coatings (CCCs) and improve its ability to release inhibitors to corroding sites have been achieved. The smart functionalised chromate conversion coating (SFCCC), developed on aluminium substrate has undergone laboratory checks and commercial runs under factory conditions confirmed its potency in improving corrosion resistance and paint adhesion to metal surfaces. In-service performance of the coating in the past three years is excellent. Keywords Adhesion, Aluminium, Aviation, Chromate Conversion Coatings, Smart Functionalised Chromate Conversion Coatings (SFCCCs

Studies on Chromium-free Conversion coatings on Aluminum

The development of a chromium-free conversion coating on aluminum has been studied using transmission electron microscopy (TEM), Auger Electron (AES) and Secondary ion mass spectroscopy (SIMS) techniques. Within the limits of the resolution of the TEM, the coating is uniformly clear and featureless. It is composed essentially of Zirconium Oxide over a diffused layer of Zirconium and Aluminum Oxide

Microstructural and Compositional Characterisation of Chromate Pretreatment on Aluminium

Chromate conversion coating developed on aluminium has been examined using SEM/EDX and CTEM/EDX with a view to having further knowledge of its intrinsic surface, plan, and sectional morphologies which will aid the understanding of their roles in improved corrosion and adhesion properties of the underlying substrate. The surface consists of spherical clusters of particulate materials. The sections, however, reveal approximately parallel, linear features which terminate at or close to the metal/coating interface, while plan views show cell-like particulate features. The coating is composed of chromium and aluminium compounds, both, probably hydrated. For a conversion coating to fully replace its chromate counterpart, most of these features may have to be replicated in the nonchromium coating material which should contain nontoxic, leachable corrosion inhibiting species

HYBRID MANGANATE-BASED CONVERSION COATING ON ALUMINIUM

This investigation describes hybrid conversion coatings and efforts at reducing the environmental foot prints of chromates. Initial modification of chromate coating solution with tannins/glycerol was patented with number NG/P/2013/755, 2014. The usual mud cracking pattern characteristics of chromate conversion coatings (CCCs) and improved ability to release inhibitors to corroding sites was achieved. Optical microscopy and corrosion tests in high humidity environment showed that the replacement of chromate/tannin with manganate/tannin and or glycerol has improved paint adhesion and corrosion resistance on aluminium substrates. Keywords: Aluminium, manganate/tannin/glycerol, adhesion, corrosion

A Review of Corrosion in Agricultural Industries

Corrosion is ubiquitous and ravages all sectors of world economies of which agricultural industries are not immune. Techniques abound to stop corrosion theoretically and practically however, human errors and over enthusiastic application of available methods of protection have reduced their applications to practical reduction of corrosion rates of materials of construction. This review highlights chemicals and agricultural wastes which enhance corrosion rates of materials of construction and practical ways of reducing their effects. Keywords: Corrosion inhibitors; fertilizers; aluminium; stainless steel; mild steel; pesticides; silage

Chromate conversion coating on Al–0.2wt.% Fe alloy

SEM and TEM investigations revealed that the chromate coating developed rapidly over the macroscopicalloy surface. The coating thickness increased over the immersion period employed in this study and wasabout 50 nm and 200 nm for coatings formed after 30 s and 120 s respectively. The coating is composed ofchromium compounds with aluminium compounds probably concentrated at the alloy/coating interface