Morphology and Properties of Zn-Al-TiO2 Composite on Mild Steel

The influence of TiO2 composite and dispersed pure Al particle on zinc alloy electrodeposited on mild steel was studied from chloride bath solution.Microstructural and mechanical properties of the alloy were investigated. The structure, surface morphology, and surface topography of the deposited alloys were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM).In addition, hardness of the coated alloys was measured. It was found that the obtained Zn-Al-TiO2 alloyexhibited more preferred surface morphology and mechanical strength compared tothe substrate. The result shows the existence of interaction between TiO2 compounds and zinc alloy particulate. It also exhibited well bright dominate zinc coating on steel surface

Suitability of local binder compositional variation on silica sand for foundry core-making

The use of local oils, namely groundnut oil, cotton seed oil and palm oil with Nigeria local clay and silica sand for the production of foundry cores has been investigated on varying composition. Addition of cassava starch, local clay, oil and moisture to sand are used to produce strong and efficient core. These oils were tested and it was found that the three could be used to produce foundry cores. The best composition was found to be core comprising 2.5% starch, 2.5% clay, 8% oil, 8% moisture and 68% sand and baked at 150oC for 1 h 30min. The tensile strength of the core were as high as 600 KN/m2

Electrochemical and Mechanical Properties of Mild Steel Electro-plated with Zn-Al.

Surface enhancement of engineering materials is necessary for preventing service failure and corrosion attack in the industries. Deposition was performed to obtain a better surface adherent coating using electroplating technique. Zn-Al film was developed with zinc and aluminum powder particles dissolved in nitric acid and sodium hydroxide respectively, to form solutions containing Zn2+ and Al3+ ions. Anomalous co-deposition on mild steel resulted into surface modification attributed to the complex alloys that was developed. The effect of deposition potential was systematically studied using Focused-ion beam scanning electron microscope (FIB-SEM), Atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infra-red (FTIR). Thick, adherent, smooth and uniform Zn-Al coating was deposited with relatively high deposition rate of 1.0 V. Experimental results indicated that the introduction of Al into the coating does significantly alter the chemical and mechanical properties of the mild steel. The microhardness value was increased by 92%; wear rate was decreased by 90% and a significant increase in the corrosion resistance was achieved based on the formation of stable deposited particles of Zn-Al

Physio-Chemical and Mechanical Behaviour of(Pinussylvestris) as Binders on Foundry Core Strength

The mechanical potential of sand core binders made withPinussylvestris has been examined. Ota silica base sand bonded with 6% of cassava starch in admixed proportion of Pinussylvestris was tested for tensile, compressive strength and permeability to establish the binding efficiency. Tensile strength of the green baked core were oven baked at 50°C, 100°C, 150°C and 200°C.The cylindrically shaped permeability specimens were tested with permeability meter. Study revealed thatPinussylvestris showed an improve properties at 6% cassava starch at 200°C

Inhibitive effect of ferrous gluconate on the electrochemical corrosion of aluminium alloy in H2SO4 solution

The use of ferrous gluconate as corrosion inhibitor on aluminium alloy in 0.5M H2SO4 solution was studied using gravimetric and potentiodynamic polarization measurements. The surface morphology of the aluminium alloy was studied after exposure to 0.5 M H2SO4 solution in the presence and absence of inhibitor using high resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HRSEM – EDS). The adsorption behaviour of the inhibitor was investigated. The results of the investigation show that increase in concentration of ferrous gluconate corresponds to an improvement on inhibition efficiency. Equally, the results showed the ferrous gluconate to be an effective corrosion inhibitor for the aluminium in the acidic medium. The results obtained from the two methods used were found to correlate with each other

Comparative Studies of Microstructural, Tribological and Corrosion Properties of Plated Zn and Zn-alloy Coatings

Difficulties in choosing appropriate material(s) for a particular application and the control of environmental menaces cannot be over emphasized. Films of Zn and Zn–Al were electrodeposited on mild steel substrates using Zn and Zn–Al alloy plating solutions respectively. Focus ion beam scanning electron microscope (FIB-SEM) images and Atomic force microscope (AFM) were used to study the surface morphology, the topography and the surface adherent properties of the coatings. The elemental composition and the phases evolved in composite coatings were measured by means of X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS). The cyclic voltammetry techniques were used to explain deposition process. The microhardness measurements and the electrochemical and wear behaviours of the deposits were investigated. Experimental results showed that Zn-Al coatings had homogeneous distribution of the fine particles deposited. These coatings had higher corrosion and wear resistances over the Zn deposited coatings as well as the substrate

Inhibition effect of potassium dichromate on the corrosion protection of mild steel reinforcement in concrete

The inhibition of potassium dichromate on the corrosion protection of mild steel embedded in concrete and partially immersed in sulphuric acid and sodium chloride environments was evaluated at ambient temperatures. The experiments were performed using electrochemical potential monitoring method. Varying quantities of the inhibitor was used. In the NaCl test medium, the effectiveness of the inhibitor improved as higher concentration was used. The best inhibition was achieved in the reinforced concrete sample admixed with 9 g potassium dichromate. Steel-reinforced concrete sample admixed with 3 and 9 g potassium dichromate inhibitor had the highest improvement in compressive strength. The potassium dichromate inhibitor was most effective amongst other inhibitor concentrations used when 7.5 g was admixed with the sample in the H2SO4 medium. The sulphuric acid medium had a deleterious effect on the strength of concrete test specimens

Experimental study of ZrB2-Si3N4on the microstructure, mechanicaland electrical properties of high grade AA8011 metal matrixcomposites

The present study evaluates the hybrid effect of ZrB2-Si3N4on the properties of AA8011 metal matrixcomposites (AMMCs) developed by two steps stir casting process. The percentage of reinforcement variesfrom 0% to 20% weight. The microstructure, hardness, ultimate tensile strength, yield strength, electricalresistivity, and conductivity were examined. From the results, it was revealed that the mechanicalproperties of the reinforced alloy are well improved compared to the unreinforced alloy. The opticalmicrograph and the scanning electron micrograph images with energy dispersive spectroscopy show theuniform distribution of the hybrid particulates of ZrB2-Si3N4with no visible porosity. The electrical re-sistivity of the developed AA8011 composites was also improved with the increase in weight percent ofthe ceramic particulates, but the electrical conductivity was drastically reduce

Inhibition Effect of Vernonia amygdalina Extract on the Corrosion of Mild Steel Reinforcement in Concrete in 3.5M NaCl Environment

The inhibition effect of Vernonia amygdalina (bitter leaf) extract on the corrosion behaviour of embedded mild steel rebar in concrete has been investigated by electrochemical potential measurement, pH and gravimetric (weight loss) methods. The results were further analysed using the two-factor ANOVA test. The experiments were performed using bitter leaf extract as a green inhibitor in 3.5% sodium chloride solution. Inhibitor extracts concentrations of 25, 50 75, and 100% were prepared from the fresh leaves of Vernonia amygdalina with distilled water. The voltage (potential) measurements were recorded with a digital voltmeter and a copper-copper sulphate electrode as the reference electrode. The pH of the test medium was measured by a pH meter. Compressive strength of each of the block samples was determined after the experiments. Weight loss values were obtained from the weight loss method (gravimetric) and the inhibitor efficiency was computed from the corrosion rate of each of the tested samples. Results showed that varied concentration of Vernonia amygdalina and the test exposure time significantly affect both the corrosion potential of embedded steel rebar in concrete and the pH of the medium. The outcome of the ANOVA test confirmed the results at 95 % confidence, and further showed that concentration of Vernonia amygdalina had greater effect on potential measurements, whereas, exposure time had greater effect on pH measurements. Vernonia amygdalina extract gave good corrosion inhibition performance of the embedded steel rebar in concrete at 25%, 50% and 75% concentrations in NaCl test medium. The highest inhibition efficiency of 90.08 % was achieved at 25% concentration, the lowest inhibitor concentration used