A. P. I. Popoola

Nanoparticle dispersion, microstructure and thermal effect of multi-doped ZrO2/SiC from sulphate induced electrolyte

Effort to improve the hardness and thermal resilient properties of coating for advanced engineering applications has necessitated this study. Zn sulphate electrolyte was induced with ZrO2-SiC composite particulate at varied current density of 1.5 and 2.0 A/cm2 for 10 minutes. The incorporated composite particles of ZrO2/SiC were varied in other to examine their mechanical responses on zinc electrolyte. The coated films were characterised with scanning electron microscope with attached electron dispersion spectroscopy (SEM/EDS) and atomic force microscopy (AFM). The micro-hardness properties of the coated and thermal aged alloy were determined with high diamond micro-hardness tester. The anti-corrosion progression was examined using linear polarization technique in 3.65% NaCl. From the results, the incorporation of the composite matrix was found to impact significantly on the surface and microhardness properties. The co-deposition of composite submicron on the zinc electrolyte revealed that homogenous grain structure was obtained. To this end, a boost in the performance characteristics was attained due to effective co-deposition parameters in the electrolyte.

Properties of Tic/Tib Modified Zn–Tic/Tib Ceramic Composite Coating on Mild Steel

Researches in the area of zinc coatings on steel are rather unending because of the unique properties and the very low cost that it offers. In this study, an attempt to develop a compact and structurally modified coating that will work against chemical and mechanical deterioration with the help of Zn–Tic/Tib was studied. Scanning electron microscope and atomic force microscope were used to study the surface morphology, the topography, and the surface adherence properties of the coatings. Micro-hardness of the deposited substrate, the electrochemical behavior and the corrosion properties of the deposits were investigated by means of high impact diamond Dura scan micro-hardness tester and gravimetric method. From the results, the deposition of Zn–Tic/Tib composite particles showed good protection against corrosion and also improved the hardness values. Hence, Zn–Tic/Tib alloy coating on mild steel can be used to improve the properties of mild steel.

Evaluation of Composition, Microstructure Characterization and Interfacial Properties of Zn—SnO2 Metal Matrix Composite Coating

In this paper the microstructure and tribological behavior of Zn—SnO2 (Zn—Sn) alloys produced through chloride and sulphates co-deposition is presented for comparison. 7.0 wt % SnO2 was added to Zn bath and deposited at 0.3 V. The interfacial effect and microchemistry of the fabricated composite was studied by optical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy disperse spectrum (EDS). The tribological behavior of the metal composites with SnO2 particles as reinforcement was studied using reciprocating sliding tester. The scanning electron microscopy (SEM) and atomic force microscope (AFM) of the composite surfaces indicates that there is good interfacial interaction between the alloy formulated matrixes made from the two baths and the substrate. Reasonable uniform distribution of Sn metal phase particulates is shown for both coating alloy. Increases in hardness and wear resistance are attributed to the uniform and coherent precipitation in the metal interface especially for Zn—7Sn—S—0.3V. In general, 7 wt % Sn additions to the bath showed more hastening to improved surface properties and better mechanical characteristics.

The effect of particulate strengthening on microstructure and mechanical characterization of binary-modified composites on mild steel:

This article presents the microstructure, tribological behavior, and hardness properties of the Zn-TiO2 functional composite coating produced using electrolytic co-deposition technique. The 7.0–13.0 weight fractions of Ti particles were incorporated in a Zn bath to form Zn-TiO2 alloy in the presence of other additives. The microstructural properties of the fabricated coating were investigated using a scanning electron microscope equipped with an energy-dispersive spectroscope, X-ray diffraction, and an atomic force microscope. The anticorrosion behavior in 3.65% NaCl medium was studied using potentiodynamic polarization technique and characterized using high-resolution optical microscope. The hardness and wear properties of the coated alloys were measured with high diamond microhardness tester and reciprocating sliding tester, respectively. From the results, the increases in hardness and wear resistance are attributed to the formation of the incorporated particulate and uniform precipitation of the metal grains at the metal lattice. The contribution of TiO2 particles especially with Zn-13Ti-0.3 V-S provides new orientation of metal–matrix-modified coated structure and decrease in friction coefficient. The anticorrosion resistance characteristics were found to improve significantly in response to concentration of additive.

Data on the effect of current density relationship on the super-alloy composite coating by electrolytic route

In this work, a detail effect of nanoparticle loading and improved process parameter on the synthesis of modified Zn-TiO2 electrocodeposited nanocomposite coating was presented. The coatings were performed at constant time of 20 minute at a stirring rate of 400 rpm at temperature of 70 °C. The effect of particle loading and input current on the properties of the electrocodeposited Nanocomposite was studied. The co-deposition was carried out at a current interval between 1.0 and 1.5 A for the coating period. The basis of bath formulation as it quantitatively and qualitatively affects the coating system was put into consideration. Hence, the electrocodeposition data for the coating properties and coating per unit area were attained. Also,the effect of annealing heat treatment on the hardness properties of the nanocomposite coatings was carried out.The annealing temperature used was 250 °C so as to ascertain the thermal stability of the coatings and to achieve homogenisation of the coating system. The weight gained under difference coating condition were attained and could be applied using modified Zn-TiO2 electrocodeposited nanocomposite coatings as an effective and safe alternative coating to chromium and other harmful coatings.

Data analysis and study of the influence of deposition power on the microstructural evolution and functionality of metallic phase composite coating

In anticipation for resolution of deterioration catastrophe on metallic materials, researches in the field of corrosion remains. Zn–Ni–NbO2 deposits were obtained on mild steel substrate using D.C. power source. The thermal stability properties of the coatings were determined by micro-hardness evaluations before and after heat treatment at 250 and 350 °C. The surface structure analysis was done by Scanning Electron Microscope and X-ray diffraction while the wear evaluations were obtained and compared. The weight gain and coating thickness were obtained and found to be in correlation with the wear results. The coating developed in this study is recommended for metallic surface improvement engineering applications.

Upgrading the Copper Value in a Waste Copper Smelter Dust with the Falcon Gravity Concentrator

The physical, chemical, mineralogical and morphological characteristic of the waste copper smelter dust (CSD) from Palabora Copper (PTY), Limpopo, South Africa, has been reported in the open literature. The bulk of this material falls within the −53 µm particle size fraction with a copper weight percent of 18.02 as determined with the XRF. The high presence of reactive gangue minerals such as mullite (42.97 wt%) and quartz (11.45 wt%) necessitates that the waste CSD be first upgraded of its copper value in the falcon gravity concentrator before subsequent hydrometallurgical treatment. As an initial step, a sample preparation was carried out to make the sample amenable to both real density determination and copper upgrade experiment, thus resulting in 97% of the particles passing the 300 µm sieve aperture (d97 = 300). The laser particle size analyzer (LPSA) was used to analyze the d97 = 300 and the results showed a %change from 90.82% to 95.59%, with a real density of 2.830 for the waste CSD. The result of the copper upgrade showed that test 8 with treatment combination of 80 rpm and 4.5 l/min gave the highest % copper grade of 1.37 which is still less than the %grade of copper in the feed(1.49%). It thus lead to the recommendation that another type of centrifugal separator that will allow the introduction of the feed as slurry so that the pulp density and feed rate can factored into the whole upgrade experiment, consequently reducing the significant amount of losses and the chances of an improved grade and recovery of copper from this waste CSD.

Laser ternary Hf-Nb-Zr composites coatings on Ti6Al4V alloy for biomedical application

Ti6Al4V alloy has been found to be the leading material for hip replacement due to its biocompatibility and good yield strength; however poor corrosion and wear properties are experienced in human tissue surroundings. Laser metal deposition was accomplished on Ti6Al4V alloy using: 25Hafnium, 50Niobium, and 25Zirconium reinforcements with the aid of Nd:YAG Rofin Sinar laser. Characterization of the produced deposits was carried out by optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy and X-ray diffraction. Hardness, corrosion and wear analyses were also done. Microstructure of 25Hf-50Nb-25Zr coatings indicated homogeneous microstructures of both α and β phases. More α acicular phases were formed than β phases. The 25Hf-50Nb-25Zr coating on Ti6Al4V reduced the content of aluminium and vanadium on the substrate. Maximum hardness value and lowest volume wear rate were obtained at laser power of 1250 W with hardness values of 599.18 HV and 0.6 m3 volume wear loss. Improvement in corrosion resistance of 99.98% was obtained. It was established that improved properties were obtained after laser surface cladding of 25Hf-50Nb-25Zr on Ti6Al4V alloy.

Enhanced dielectric performance and energy storage density of polymer/graphene nanocomposites prepared by dual fabrication

Polymer/graphene nanocomposites (PGNs) have shown great potential as dielectric and energy storage materials. However, insolubility of graphene in most solvents, hydrophobic behaviour and poor dispersion in polymer matrix restrict wider fabrications and applications of PGNs. In this study, we present co-fabricated PGNs engineered by solution blending and melt compounding methods with improved dielectric performance. Further processing of PGNs by melt mixing after solution blending not only improved dispersion of graphene in the matrix but also ensured good interfacial interaction of the composites’ constituents and reduction of oxygen content in PGNs. Graphene nanoplatelets used in this study was slightly functionalized (fGNPs) to enhance dispersion in the polymer matrix. It was later characterized using Fourier transform infrared (FTIR) and Raman spectrometer. Scanning electron microscope (SEM) was used in morphological study of the fabricated composites. Dielectric properties, electrical conductivity, breakdown strength and energy storage capacity of the fabricated composites were investigated. The results obtained showed well-dispersed fGNPs in poly (vinylidene fluoride) (PVDF) matrix and improved dielectric performance. For instance, with 3.34 wt% and 6.67 wt% fGNPs co-fabricated composites, dielectric constant increased from about 9 for neat PVDF to 9930 and 38,418 at 100 Hz, respectively. While 7588 and 12,046 were respectively measured for solution blended-only composites at similar fGNPs content. These resulted to about 176.9% and 376.4% increase in energy storage density with 3.34 wt% and 6.67 wt% fGNPs co-fabricated composites when compared to their counterparts. These results were also credited to strong bonding, reduction of oxygen and recovered graphene structure by melt-mixing approach.

Data on the influence of TiN on wear and corrosion behavior of Ti–6Al–4V alloy fabricated through spark plasma sintering

Data about bulk properties of Ti–6Al–4V based composites specimen achieved by powder metallurgy route using spark plasma sintering (SPS) technique is presented, with focus on the effect of TiN particles on wear and corrosion behavior of the resultant composites. Two microsized kind of powders are combined; Ti–6Al–4V and TiN. The powder mixing and SPS processing has been enhanced and consolidated.