The development of natural biomaterials is not regarded as a new area of science, but has existed... more The development of natural biomaterials is not regarded as a new area of science, but has existed for centuries. The use of natural products as a biomaterial is currently undergoing a renaissance in the biomedical field. The major limitations of natural biomaterials are due to the immunogenic response that can occur following implantation and the lot-to-lot variability in molecular structure associated with animal sourcing. The chemical stability and biocompatibility of natural products in the body greatly accounts for their utilization in recent times. The paper succinctly defines biomaterials in terms of natural products and also that natural products as materials in biomedical fields are considerably versatile and promising. The various types of natural products and forms of biomaterials are highlighted. Three main areas of applications of natural products as materials in medicine are described, namely, wound management products, drug delivery systems, and tissue engineering. Thi...
IOP Conference Series: Materials Science and Engineering
Conventional duplex stainless steel degrade in wear and mechanical properties at high temperature... more Conventional duplex stainless steel degrade in wear and mechanical properties at high temperature. Attempts have been made by researchers to solve this problems leading to the dispersion of second phase particles into duplex matrix. Powder metallurgy methods have been used to fabricate dispersion strengthened steels with a challenge of obtaining fully dense composite and grain growth. This could be resolved by appropriate selection of sintering parameters especially temperature. In this research, spark plasma sintering was utilized to fabricate nanostructured duplex stainless steel grade SAF 2205 with 5 wt.% nano TiN addition at different temperatures ranging from 1000 °C to 1200 °C. The effect of sintering temperature on the microstructure, density, hardness and wear of the samples was investigated. The results showed that the densities and grain sizes of the sintered nanocomposites increased with increasing the sintering temperature. The microstructures reveal ferrite and austenite grains with fine precipitates within the ferrite grains. The study of the hardness and wear behaviors, of the samples indicated that the optimum properties were obtained for the sintering temperature of 1150 °C.
Abstract In this study, the microstructural and densification behavior of titanium nitride (TiN) ... more Abstract In this study, the microstructural and densification behavior of titanium nitride (TiN) and titanium carbonitride (TiCN) reinforced Ti-6Al-4V were investigated under an applied pressure of 50 MPa, sintering temperatures of 1000–1100 °C, heating rate of 100 °C/min and dwell time of 10–20 min through spark plasma sintering technique. Results show that the microstructural transformation of the titanium matrix composite comprises of a mixture of lamellar colonies with β grain boundaries and nanoparticles with an average grain size range of 4.5–6.0 μm. Furthermore, an addition of nanoceramics TiN/TiCN resulted in microstructural transformation, uniform particle distribution within the metal matrix and along the grain boundary. However, the sintered relative density of the composites decreased with the percentage increase in TiCN, while fully dense composites were obtained at a sintering temperature of 1100 °C. Microhardness values of the sintered composites reach a greater level in comparison to Ti-6Al-4V alloy while fracture morphology of the sintered composites with addition of nanoceramics (TiN/TiCN) displayed a transgranular transformation within the matrix accompanied with fine dimple features.
Abstract The influence of sintering temperature and holding time on microstructure, corrosion and... more Abstract The influence of sintering temperature and holding time on microstructure, corrosion and wear of spark plasma sintered duplex stainless steel (SAF 2205) reinforced with nano-sized TiN were investigated. Potentiodynamic polarization measurement was used to study corrosion behaviour in 3.5 wt% NaCl while the wear tests were conducted via universal micro-tribotester. Density and hardness increased with sintering temperature and holding time with maximum densification and hardness achieved at 1150 °C and 15 min respectively. The microstructure shows austenite (γ) and ferrite (α) structure with the austenite phase decreasing as sintering temperature and holding time increases. Optimal corrosion resistance was obtained for composite sintered for 10 min at 1100 °C while that sintered at 1150 °C and 10 min had the highest wear resistance.
Journal of Materials Research and Technology, 2017
Abstract This research optimized spark plasma sintering (SPS) process parameters in terms of sint... more Abstract This research optimized spark plasma sintering (SPS) process parameters in terms of sintering temperature, holding time and heating rate for the development of a nano-structured duplex stainless steel (SAF 2205 grade) reinforced with titanium nitride (TiN). The mixed powders were sintered using an automated spark plasma sintering machine (model HHPD-25, FCT GmbH, Germany). Characterization was performed using X-ray diffraction and scanning electron microscopy. Density and hardness of the composites were investigated. The XRD result showed the formation of FeN 0.068 . SEM/EDS revealed the presence of nano ranged particles of TiN segregated at the grain boundaries of the duplex matrix. A decrease in hardness and densification was observed when sintering temperature and heating rate were 1200 °C and 150 °C/min respectively. The optimum properties were obtained in composites sintered at 1150 °C for 15 min and 100 °C/min. The composite grades irrespective of the process parameters exhibited similar shrinkage behavior, which is characterized by three distinctive peaks, which is an indication of good densification phenomena.
The International Journal of Advanced Manufacturing Technology, 2017
The synergistic effects of monoethylene glycol (MEG) and leaf extract of Sida acuta on UNS S30403... more The synergistic effects of monoethylene glycol (MEG) and leaf extract of Sida acuta on UNS S30403 stainless steel under sand deposit in aerated 3.5-wt.% NaCl solution were studied through open circuit potential measurements, potentiodynamic polarization curves, and atomic force microscopy. Phytochemical analysis of the Sida acuta shows the presence of phenol, alkaloid, steroid, flavonoid, and saponin. It was found that the leaf extract inhibited the general and localized corrosion of the stainless steel, especially at a concentration of 400 ppm. With the leaf extract alone, the corrosion resistance increases with increase in inhibitor dosage up until 400 ppm; then, a drop in corrosion resistance was experienced at 600 ppm. However, with the addition of 20 wt.% monoethylene glycol to the environment, the green inhibitor was only effective at 600-ppm dosage. These results show that the presence of MEG can only be tolerated with the inhibitor at higher inhibitor concentrations for this alloy in the environment under study. Adsorption of Sida acuta inhibitor on the steel surface does not follow any adsorption isotherm.
Abstract Aluminum alloy 6063 (AA6063) composite with varying proportion of snail-shell-ash (SSA) ... more Abstract Aluminum alloy 6063 (AA6063) composite with varying proportion of snail-shell-ash (SSA) and silicon carbide (SiC) reinforcement has been developed by stir-casting. Hardness and erosion-corrosion characteristics of the composite were studied. Erosion-corrosion behaviour of the composite was studied in a mono-ethylene glycol (MEG)-water environment with 20% v/v of ethylene glycol and 0.1 g/L silica sand particles using a re-designed miniature submerged impinging jet rig. SEM-EDX of the as-cast composites showed the presence of the particulates distributed in the matrix. The hardness of the aluminum alloy was enhanced up to a maximum value (with the addition of 7.5 wt % SiC+7.5 wt % SSA). However, hardness values declined when (10 wt % SSA+10 wt % SiC) was used as reinforcing phase. Erosion-corrosion studies showed that erosion component dominates the total material loss and the composite with highest hardness displaying better erosion-corrosion resistance. Also, addition of MEG to the slurry resulted in lower erosion-enhance corrosion and total material loss due to erosion-corrosion. SEM images of the damaged composite showed that the damage mechanism is dominated by ploughing and indentation.
Effects of sida acuta extract on the corrosion behaviour of API 5L-X65 steel under sand deposit i... more Effects of sida acuta extract on the corrosion behaviour of API 5L-X65 steel under sand deposit in CO2 saturated oilfield brine has been studied. Tafel extrapolation method has been employed to determine the corrosion rate of the alloy under sand deposit with and without sida acuta extract. Atomic force microscopy was employed to study the surface roughness of the steel. Phytochemical analysis and Fourier transformed infrared (FTIR) spectroscopy was used to identify the functional groups present in the extract. The presence of sand retarded the inhibitor efficiency at lower dosage but better corrosion inhibition was obtained at higher inhibitor dosage.
2018 IEEE 9th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), 2018
The In this study, duplex stainless steel containing 5 vol% TiN nanoparticles was fabricated by m... more The In this study, duplex stainless steel containing 5 vol% TiN nanoparticles was fabricated by means of spark plasma sintering (SPS). The effect of sintering holding time, microstructure, density, microhardness, corrosion and wear was investigated. The results showed that ferrite and austenite were the dominant phase. New phase of chromium nitride precipitated (Cr2N) was formed when sintering holding time was increased above 5 min. The volume fraction of the precipitated nitrides increased with the increase in the holding time. The microhardness and density of the composites was increased with the increase in holding time. The corrosion resistance of the composites degraded with the increase in the holding time while, the best wear performance was attained with 10 min holding time.
Densification mechanism of Ti–6Al–4V–TiN–TiCN powders was processed using spark plasma sintering ... more Densification mechanism of Ti–6Al–4V–TiN–TiCN powders was processed using spark plasma sintering route. The powder consolidation was carried out at the temperatures of 1000 °C to 1100 °C and constant pressure of 50 MPa with different holding time of 10 and 20 mins. The relative density of the sintered sample reaches 99%, which was as a function of the SPS conditions. Results indicates that with rising in sintering temperatures, relative densities of the composites were found to be increasing, while the microstructure shows some level of rapid growth and provided the optimal combination of dense microstructure. The fractography of the sintered samples at different temperatures and holding time was observed to investigate the sintering mechanism as well.
IOP Conference Series: Materials Science and Engineering
Duplex stainless steel (SAF 2205) reinforced with titanium nitride (TiN) nanoparticles ranging fr... more Duplex stainless steel (SAF 2205) reinforced with titanium nitride (TiN) nanoparticles ranging from 0 to 8 wt% were fabricated in vacuum via spark plasma sintering (SPS) using optimized SPS process parameter of 1150°C, 10 min and 100°C/min. The influence of TiN addition on the densification and shrinkage mechanism of the fabricated duplex stainless steel composite were evaluated. The results indicate even dispersion of the TiN nanoparticles in the steel matrix during tubular mixing. The displacement and shrinkage rates showed three densification stages relating to micro-nano particles rearrangement, plastic deformation of the particles and rapid densification of the composite. The steel composite samples displayed relatively high densities in the range of 96-99 % of the calculated theoretical density but were noted to decrease with TiN content.
Studies of thermo-oxidative and fire-resistant properties of the polypropylene/multi-walled carbo... more Studies of thermo-oxidative and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by melt intercalation are discussed. The effective kinetic parameters of the PP/MWCNT thermo-oxidative decomposition were computed according to the model-based kinetic analysis. The thermo-oxidative decomposition behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy.
International Journal of Refractory Metals and Hard Materials, 2017
Abstract Erosion-corrosion is a complex degradation mechanism prevalent in multiphase system and ... more Abstract Erosion-corrosion is a complex degradation mechanism prevalent in multiphase system and material selection is a strategy to mitigate the destructive process. This study evaluates the candidature of spark plasma sintered WC-12Co in aggressive media and with sand particles via rotating cylinder electrode. Corrosion and hardness tests were carried out, and the cermets surface morphology was examined. General corrosion results from total mass loss showed the least degradation resistance in sulphuric acid which informed the recommendation of the alloy for industrial applications in simulated mine water and seawater. Localised attack parameters from cyclic potentiodynamic polarization and the micrographs were well correlated.
The field of proton exchange membrane fuel cells (PEMFCs) has been of primary interest in transpo... more The field of proton exchange membrane fuel cells (PEMFCs) has been of primary interest in transportation applications as a result of their low pollutant emissions and relatively high efficiency. Bipolar plates are the vital components of these devices and are often exposed to corrosive environments due to their operational processes. Potentiodynamic polarization is used by researchers to investigate the material behavior of BPP used in the PEMFC applications. This paper aims to describe the application of electrochemical analysis in understanding the material behavior of PEMFC components, with a particular focus on the utilization of potentiodynamic polarization to provide material degradation information of bipolar plates. The potentiodynamic polarization test examines the material behavior of BPPs in terms of using voltage and current density change. This paper, therefore, combined potential applications of potentiodynamic polarization analysis technique to explore the BPP materia...
The development of natural biomaterials is not regarded as a new area of science, but has existed... more The development of natural biomaterials is not regarded as a new area of science, but has existed for centuries. The use of natural products as a biomaterial is currently undergoing a renaissance in the biomedical field. The major limitations of natural biomaterials are due to the immunogenic response that can occur following implantation and the lot-to-lot variability in molecular structure associated with animal sourcing. The chemical stability and biocompatibility of natural products in the body greatly accounts for their utilization in recent times. The paper succinctly defines biomaterials in terms of natural products and also that natural products as materials in biomedical fields are considerably versatile and promising. The various types of natural products and forms of biomaterials are highlighted. Three main areas of applications of natural products as materials in medicine are described, namely, wound management products, drug delivery systems, and tissue engineering. Thi...
IOP Conference Series: Materials Science and Engineering
Conventional duplex stainless steel degrade in wear and mechanical properties at high temperature... more Conventional duplex stainless steel degrade in wear and mechanical properties at high temperature. Attempts have been made by researchers to solve this problems leading to the dispersion of second phase particles into duplex matrix. Powder metallurgy methods have been used to fabricate dispersion strengthened steels with a challenge of obtaining fully dense composite and grain growth. This could be resolved by appropriate selection of sintering parameters especially temperature. In this research, spark plasma sintering was utilized to fabricate nanostructured duplex stainless steel grade SAF 2205 with 5 wt.% nano TiN addition at different temperatures ranging from 1000 °C to 1200 °C. The effect of sintering temperature on the microstructure, density, hardness and wear of the samples was investigated. The results showed that the densities and grain sizes of the sintered nanocomposites increased with increasing the sintering temperature. The microstructures reveal ferrite and austenite grains with fine precipitates within the ferrite grains. The study of the hardness and wear behaviors, of the samples indicated that the optimum properties were obtained for the sintering temperature of 1150 °C.
Abstract In this study, the microstructural and densification behavior of titanium nitride (TiN) ... more Abstract In this study, the microstructural and densification behavior of titanium nitride (TiN) and titanium carbonitride (TiCN) reinforced Ti-6Al-4V were investigated under an applied pressure of 50 MPa, sintering temperatures of 1000–1100 °C, heating rate of 100 °C/min and dwell time of 10–20 min through spark plasma sintering technique. Results show that the microstructural transformation of the titanium matrix composite comprises of a mixture of lamellar colonies with β grain boundaries and nanoparticles with an average grain size range of 4.5–6.0 μm. Furthermore, an addition of nanoceramics TiN/TiCN resulted in microstructural transformation, uniform particle distribution within the metal matrix and along the grain boundary. However, the sintered relative density of the composites decreased with the percentage increase in TiCN, while fully dense composites were obtained at a sintering temperature of 1100 °C. Microhardness values of the sintered composites reach a greater level in comparison to Ti-6Al-4V alloy while fracture morphology of the sintered composites with addition of nanoceramics (TiN/TiCN) displayed a transgranular transformation within the matrix accompanied with fine dimple features.
Abstract The influence of sintering temperature and holding time on microstructure, corrosion and... more Abstract The influence of sintering temperature and holding time on microstructure, corrosion and wear of spark plasma sintered duplex stainless steel (SAF 2205) reinforced with nano-sized TiN were investigated. Potentiodynamic polarization measurement was used to study corrosion behaviour in 3.5 wt% NaCl while the wear tests were conducted via universal micro-tribotester. Density and hardness increased with sintering temperature and holding time with maximum densification and hardness achieved at 1150 °C and 15 min respectively. The microstructure shows austenite (γ) and ferrite (α) structure with the austenite phase decreasing as sintering temperature and holding time increases. Optimal corrosion resistance was obtained for composite sintered for 10 min at 1100 °C while that sintered at 1150 °C and 10 min had the highest wear resistance.
Journal of Materials Research and Technology, 2017
Abstract This research optimized spark plasma sintering (SPS) process parameters in terms of sint... more Abstract This research optimized spark plasma sintering (SPS) process parameters in terms of sintering temperature, holding time and heating rate for the development of a nano-structured duplex stainless steel (SAF 2205 grade) reinforced with titanium nitride (TiN). The mixed powders were sintered using an automated spark plasma sintering machine (model HHPD-25, FCT GmbH, Germany). Characterization was performed using X-ray diffraction and scanning electron microscopy. Density and hardness of the composites were investigated. The XRD result showed the formation of FeN 0.068 . SEM/EDS revealed the presence of nano ranged particles of TiN segregated at the grain boundaries of the duplex matrix. A decrease in hardness and densification was observed when sintering temperature and heating rate were 1200 °C and 150 °C/min respectively. The optimum properties were obtained in composites sintered at 1150 °C for 15 min and 100 °C/min. The composite grades irrespective of the process parameters exhibited similar shrinkage behavior, which is characterized by three distinctive peaks, which is an indication of good densification phenomena.
The International Journal of Advanced Manufacturing Technology, 2017
The synergistic effects of monoethylene glycol (MEG) and leaf extract of Sida acuta on UNS S30403... more The synergistic effects of monoethylene glycol (MEG) and leaf extract of Sida acuta on UNS S30403 stainless steel under sand deposit in aerated 3.5-wt.% NaCl solution were studied through open circuit potential measurements, potentiodynamic polarization curves, and atomic force microscopy. Phytochemical analysis of the Sida acuta shows the presence of phenol, alkaloid, steroid, flavonoid, and saponin. It was found that the leaf extract inhibited the general and localized corrosion of the stainless steel, especially at a concentration of 400 ppm. With the leaf extract alone, the corrosion resistance increases with increase in inhibitor dosage up until 400 ppm; then, a drop in corrosion resistance was experienced at 600 ppm. However, with the addition of 20 wt.% monoethylene glycol to the environment, the green inhibitor was only effective at 600-ppm dosage. These results show that the presence of MEG can only be tolerated with the inhibitor at higher inhibitor concentrations for this alloy in the environment under study. Adsorption of Sida acuta inhibitor on the steel surface does not follow any adsorption isotherm.
Abstract Aluminum alloy 6063 (AA6063) composite with varying proportion of snail-shell-ash (SSA) ... more Abstract Aluminum alloy 6063 (AA6063) composite with varying proportion of snail-shell-ash (SSA) and silicon carbide (SiC) reinforcement has been developed by stir-casting. Hardness and erosion-corrosion characteristics of the composite were studied. Erosion-corrosion behaviour of the composite was studied in a mono-ethylene glycol (MEG)-water environment with 20% v/v of ethylene glycol and 0.1 g/L silica sand particles using a re-designed miniature submerged impinging jet rig. SEM-EDX of the as-cast composites showed the presence of the particulates distributed in the matrix. The hardness of the aluminum alloy was enhanced up to a maximum value (with the addition of 7.5 wt % SiC+7.5 wt % SSA). However, hardness values declined when (10 wt % SSA+10 wt % SiC) was used as reinforcing phase. Erosion-corrosion studies showed that erosion component dominates the total material loss and the composite with highest hardness displaying better erosion-corrosion resistance. Also, addition of MEG to the slurry resulted in lower erosion-enhance corrosion and total material loss due to erosion-corrosion. SEM images of the damaged composite showed that the damage mechanism is dominated by ploughing and indentation.
Effects of sida acuta extract on the corrosion behaviour of API 5L-X65 steel under sand deposit i... more Effects of sida acuta extract on the corrosion behaviour of API 5L-X65 steel under sand deposit in CO2 saturated oilfield brine has been studied. Tafel extrapolation method has been employed to determine the corrosion rate of the alloy under sand deposit with and without sida acuta extract. Atomic force microscopy was employed to study the surface roughness of the steel. Phytochemical analysis and Fourier transformed infrared (FTIR) spectroscopy was used to identify the functional groups present in the extract. The presence of sand retarded the inhibitor efficiency at lower dosage but better corrosion inhibition was obtained at higher inhibitor dosage.
2018 IEEE 9th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), 2018
The In this study, duplex stainless steel containing 5 vol% TiN nanoparticles was fabricated by m... more The In this study, duplex stainless steel containing 5 vol% TiN nanoparticles was fabricated by means of spark plasma sintering (SPS). The effect of sintering holding time, microstructure, density, microhardness, corrosion and wear was investigated. The results showed that ferrite and austenite were the dominant phase. New phase of chromium nitride precipitated (Cr2N) was formed when sintering holding time was increased above 5 min. The volume fraction of the precipitated nitrides increased with the increase in the holding time. The microhardness and density of the composites was increased with the increase in holding time. The corrosion resistance of the composites degraded with the increase in the holding time while, the best wear performance was attained with 10 min holding time.
Densification mechanism of Ti–6Al–4V–TiN–TiCN powders was processed using spark plasma sintering ... more Densification mechanism of Ti–6Al–4V–TiN–TiCN powders was processed using spark plasma sintering route. The powder consolidation was carried out at the temperatures of 1000 °C to 1100 °C and constant pressure of 50 MPa with different holding time of 10 and 20 mins. The relative density of the sintered sample reaches 99%, which was as a function of the SPS conditions. Results indicates that with rising in sintering temperatures, relative densities of the composites were found to be increasing, while the microstructure shows some level of rapid growth and provided the optimal combination of dense microstructure. The fractography of the sintered samples at different temperatures and holding time was observed to investigate the sintering mechanism as well.
IOP Conference Series: Materials Science and Engineering
Duplex stainless steel (SAF 2205) reinforced with titanium nitride (TiN) nanoparticles ranging fr... more Duplex stainless steel (SAF 2205) reinforced with titanium nitride (TiN) nanoparticles ranging from 0 to 8 wt% were fabricated in vacuum via spark plasma sintering (SPS) using optimized SPS process parameter of 1150°C, 10 min and 100°C/min. The influence of TiN addition on the densification and shrinkage mechanism of the fabricated duplex stainless steel composite were evaluated. The results indicate even dispersion of the TiN nanoparticles in the steel matrix during tubular mixing. The displacement and shrinkage rates showed three densification stages relating to micro-nano particles rearrangement, plastic deformation of the particles and rapid densification of the composite. The steel composite samples displayed relatively high densities in the range of 96-99 % of the calculated theoretical density but were noted to decrease with TiN content.
Studies of thermo-oxidative and fire-resistant properties of the polypropylene/multi-walled carbo... more Studies of thermo-oxidative and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by melt intercalation are discussed. The effective kinetic parameters of the PP/MWCNT thermo-oxidative decomposition were computed according to the model-based kinetic analysis. The thermo-oxidative decomposition behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy.
International Journal of Refractory Metals and Hard Materials, 2017
Abstract Erosion-corrosion is a complex degradation mechanism prevalent in multiphase system and ... more Abstract Erosion-corrosion is a complex degradation mechanism prevalent in multiphase system and material selection is a strategy to mitigate the destructive process. This study evaluates the candidature of spark plasma sintered WC-12Co in aggressive media and with sand particles via rotating cylinder electrode. Corrosion and hardness tests were carried out, and the cermets surface morphology was examined. General corrosion results from total mass loss showed the least degradation resistance in sulphuric acid which informed the recommendation of the alloy for industrial applications in simulated mine water and seawater. Localised attack parameters from cyclic potentiodynamic polarization and the micrographs were well correlated.
The field of proton exchange membrane fuel cells (PEMFCs) has been of primary interest in transpo... more The field of proton exchange membrane fuel cells (PEMFCs) has been of primary interest in transportation applications as a result of their low pollutant emissions and relatively high efficiency. Bipolar plates are the vital components of these devices and are often exposed to corrosive environments due to their operational processes. Potentiodynamic polarization is used by researchers to investigate the material behavior of BPP used in the PEMFC applications. This paper aims to describe the application of electrochemical analysis in understanding the material behavior of PEMFC components, with a particular focus on the utilization of potentiodynamic polarization to provide material degradation information of bipolar plates. The potentiodynamic polarization test examines the material behavior of BPPs in terms of using voltage and current density change. This paper, therefore, combined potential applications of potentiodynamic polarization analysis technique to explore the BPP materia...
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