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The Impact of Selected Bio-Based Carburising Agents on Mechanical and Tribocorrosion Behaviour of Medium Carbon Steel
Get PDFCarburisation is a surface engineering method exploited for low/medium carbon steels to achieve
blended funtionalisations in tribological and corrosion-resistant properties. However, much work
has not been carried out to study the reaction of carburised medium carbon steel to combined
actions by abrasion and electrochemical wear. This paper focuses on investigating the corrosion
polarisation tendency of the various blends of the solution on carburised and as-received medium
carbon steel using potentiodynamic polarisation tests and weight loss analysis. Hence, palm
kernel oil (PKO) and sodium chloride (NaCl) of 20.475 g prepared with 100 ml of distilled water
as a control medium were employed for this study. The corrosion susceptibility of the asreceived
medium carbon steel (uncarburised and carburised) materials, in differing
concentrations as 0 ml, 0.2 ml, 0.4 ml, 0.6 ml, and 0.8 ml test solution under differing applied
potentials were evaluated employing a polarisation tool. The corrosion susceptibility of the asreceived
medium carbon steel (uncarburised and carburised) materials, in differing
concentrations as 0 ml, 0.2 ml, 0.4 ml, 0.6 ml, and 0.8 ml test solution under differing applied
potentials were evaluated employing a polarisation tool. Particularly, in the pitting environment
containing 0.20475 M NaCl, numerous corrosion pits are formed inside the wear track on the
untreated specimen at potentials much lower than the pitting potential, while no corrosion pits
are observed inside the wear track on the carburized specimen at anodic potentials as high as
1000 mV(SCE). The SEM/EDS also demonstrated the microstructural behavior of the surface
oxides, spots, fractures, and corrosive pits at contact with the palm kernel oil (PKO) and sodium
chloride (NaCl) solution environment. Comparatively, the result showed that there was a
significant improvement in the mechanical properties of the carburised medium carbon steel
material used to develop the hammers in this study
Neural Network-Based Wind Turbine Power Curve Models Using Several Wind Farms' Influencing Parameters and Topography
Get PDFWind turbine power curve (WTPC) modelling is of great importance for energy assessment and
forecasting. In previous works, WTPC models were developed based only on wind speed. However, in
this research, we developed modelling methods that represent actual WTPC by extensively considering
wind farms’ topography and several field conditions (other than wind speed only) that are found to
influence the power output of wind turbines, such as climate variability, the effect of neighbouring wind
turbines, turbulence intensity, wake effect, ambient temperature, atmospheric pressure, wind direction,
and terrain conditions. We analyse the radial basis function (RBF) and multi-layer perceptron (MLP)
architectures for sensitivity and modelling accuracy. A filtered dataset is passed into the models, and
fitting accuracies are computed alongside sensitivity analysis. The best-performing models are compared
with numerous parametric and non-parametric WTPC modelling schemes. It is found that the quantile
filtering (QF-NN) models outperform all other models in terms of fitting accuracy and outperform all
selected hybrid models in terms of computation time
Corrosion inhibition of grapeseed oil on high carbon steel and ferrovanadium alloy in H2SO4 solution: Experimental and statistical analysis
Get PDFExperimental and statistical analysis of the corrosion inhibition properties of grapeseed oil (GSO) on high carbon steel (HCS) and ferrovanadium (FVA) in 0.25 M H2SO4 solution was done. Results from gravimetric analysis show GSO performed more effectively on HCS with average inhibition efficiency above 90% at all concentrations compared to FVA where the values where generally around 70% at 360 h of exposure. Inhibition efficiency results did not vary significantly with GSO concentration compared to exposure time over 360 h. Secondly, inhibition efficiency values increased with respect to exposure time from initiation. ANOVA statistical method at 95% confidence level and significance level of 0.05 shows the sources of data variation (exposure time and inhibitor concentration) has minimal influence on the inhibition performance output of GSO. This indicate they are statistically indeterminate. The inhibition data is due to factors relating to presence of phytochemical properties, organo-metallic interaction, adsorption mode and influence of corrosive species. Data from standard deviation shows GSO inhibition efficiency data varies minimally from mean inhibition values from HCS which contrast the values obtained for FVA which were significantly high. The results show greater thermodynamic stability of GSO inhibition on HCS compared to FVA. 82% of GSO inhibition data from its action on HCS are above 70% inhibition compared to 22% for FVA
Comparative analysis of the corrosion resistance data of aluminium alloy 4032 and 4004, magnesium titanium alloy and aluminium vanadium alloy in dilute H2SO4, NaCl and acid chloride solutions
Get PDFComparative study of the corrosion resistance of Al 4032, Al 4004, Mg-Ti and Al-V alloy were performed in H2SO4 solution, NaCl solution and H2SO4/NaCl solution for 480 h. Mg-Ti exhibited the highest corrosion rate values in H2SO4 solution, culminating at values between 0.242 mm/y and 6.081 mm/y compared to Al 4004 and Al 4032 which exhibited the lowest values. Corrosion rate of Al-V were generally stable but exhibited a parabolic behavior beyond 0.025 M H2SO4 concentration. In NaCl, Mg-Ti alloy exhibited the highest corrosion rate values culminating at values from 0.180 mm/y to 0.794 mm/y. Al 4004 and Al-V alloys exhibited the lowest corrosion rate values. The corrosion rate of Al 4032 was generally stable throughout the exposure hours. Admixture of H2SO4 and NaCl did not significantly influence the corrosion resistance of the alloys. ANOVA statistical data for Al 4032, Al 4004 and Al-V alloys in NaCl solution are statistically irrelevant with respect to corrosion resistance of the alloys compared to the value for Mg-Ti where electrolyte concentration is statistically relevant with statistical relevance factor of 96.94%. Electrolyte concentration is the only statistically relevant variation influencing the corrosion resistance for the alloys in H2SO4 with values of 98.44%, 97.66%, 94.96% and 98.38%. This was also observed in H2SO4/NaCl solution with corresponding values of 90.02%, 94.35%, 91.71% and 86.7%. The highest mean values for Al 4032, Mg-Ti, Al 4004 and Al-V alloys occurred at 0.05 M, 0.0125 M and 0.00625 M H2SO4 solutions. Mg-Ti exhibits the highest mean corrosion rate values of 5.93 mm/y while Al-V exhibits the lowest values -0.10 mm/y. The SD values were generally low. The mean corrosion rate values for Al 4032, Al 4004 and Al-V alloys in NaCl are significantly below 0 compared to Mg-Ti whose values are greater than 0 but relatively low
Microstructural Characteristics and Wear Behavior of Sintered Ni‑Modified Ti–xTiB2 Composites
Get PDFTitanium matrix composites were manufactured
using pulsed plasma sintering with the addition of
5 wt.% Ni and TiB2
(x = 5, 10, 15, 20 wt.%) particles at a
sintering temperature of 1000 °C, a heating rate of 100 °C/
min, and a holding time (300 s) at an applied pressure of
50 MPa. The study examines the densification, phase evolution,
hardness, microstructure, and wear behavior of Ti–Ni
alloys with different ceramic (
TiB2) contents. The results
show that increasing TiB2
content decreases relative density
from 99 to 97% while increasing hardness from 229 to 586
HV0.1.
The addition of Ni particles resulted in laminar α-Ti
with well-defined β-Ti grain boundaries. Furthermore, the
microstructural studies have revealed a dual-phase beta and
alpha Ti phase with uniformly dispersed TiB2
content. As a
result of the interactions between β-Ti and Ni during sintering,
an intermetallic (
Ti2Ni) eutectoid phase was formed.
The presence of Ni and TiB2
particles reduces the average
coefficient of friction, wear volume, and wear rate. Therefore,
the reinforced titanium matrix composites wear track
surfaces exhibited a combination of abrasive and adhesive
wear modes
Mathematical Models for Predicting the Mechanical Properties of Poly(Lactic Acid) for Load-Bearing Applications
Get PDFIn order to widen the areas of application of poly (lactic acid) (PLA), there has been a
multiplicity of experiments. This study attempts to develop mathematical models for
predicting the mechanical properties of PLA to reduce the number of experimental runs
and material wastage. The melt-cast method produced unreinforced PLA samples with
different slenderness ratios (λ) in triplicate using. The samples were subjected to a
compression test to obtain the mechanical properties captured at three main points on
the stress-strain curve: yield, ultimate stress, and fracture. Regression models were
developed from the data obtained at the three points, and their validity was examined by
testing them against the previous relevant experimental studies from various authors. The
coefficient of determination (R2) and coefficient of correlation (ρ) was also examined for
each model to establish their degree of correctness further. Analyses show that the
developed models give reasonable approximations of some of the properties examined. The mass (M) and the modulus of elasticity (E) were the most accurately predictable
properties with [R2, ρ] of [99.97%, 0.9998] and [91.55%, 0.9568], respectively. Results also
show that apart from the melt-cast method, the compressive modulus of PLA (both
circular and rectangular cross-sections test samples) produced via injection molding and
fused filament fabrication can be predicted with near accuracy using the model developed
in this study. This study gives researchers the tools needed to avoid material wastage by
having close-to-real values of the mechanical properties of PLA through prediction before
carrying out any experiment
Corrosion and Wear Properties of Aluminium AA7075 Reinforced Chitosan
Get PDFThis study explores the mechanical behaviours of AA7075/chitosan
composite at a mesh size of 90μm formed through percentage range of 3, 6, 9, and
12 wt. % by stir casting method. SEM revealed existence of grain at the borderline
of the matrix as increased in reinforcing agent resulted to evenly dispersal of fibre
links in the micrograph. XRD analysis showed existence of Hydroxyapatite,
Ca10(PO4)6(OH)2, as seen by many high-intensity peaks in the diffract gram of the
dominant crystal. The wear rate of the samples is seen to be increasing from the
control, peaking at 1.78 % at AA7075+9 wt. % chitosan before dropping by
0.04 % at AA7075+12 wt. % chitosan. The corrosion study revealed that
AA7075+9 wt. % chitosan exhibits minimal corrosion rate in comparison to other
matrixes. The findings shows that chitosan-reinforced AMMC can be produced
using a cost-effective stir casting process while still meeting design requirements
for use in electrical cables due to improved mechanical strength and electrical
conductivity, as well as lightweight household utensils due to chitosan's
antibacterial properties
Insight on the Dynamics of Corrosion and Anti-Corrosion Protection Progresses on Steel: A Brief Review
Get PDFSteel is one of the prevalent metals used in many applications; however, steel corrosion and its
severe deterioration are associated with temperature, pressure, and atmospheric climate change.
The steel failure from pitting evolution results in high cost and manufacturing flaws due to
design error and extreme environmental conditions. Several preventive measures have often been
adopted to resist this failure. This paper reviews the challenges of materials in application as
relates to structural deformation, corrosion, and mechanical failure. The impact of new inhibitive
activities for engineering component advances was ascertained. The review concluded that
failure of engineering materials regardless of the manufacturing flaws can be addressed through
component proper design and physiochemical activities of extracts with responsive ions. It also
elucidates that metallic steel protection against sudden failure depends on the nature of surface
preparation and stress initiation at the surfaces. The different progression through which
corrosion occurs and the methods for mitigation were established in this work
Experimental Investigation of the Effect of Surfactant–Polymer Flooding on Enhanced Oil Recovery for Medium Crude Oil
No full textHigh technical and financial risks are involved in exploring and exploiting new fields;
hence, greater focus has placed on the development of environmentally friendly, cost-effective, and
enhanced oil recovery (EOR) options for existing fields. For reservoirs producing high-density
crudes and those with high interfacial tensions, water flooding is usually less effective due to density
differences—hence the advent of polymer and surfactant flooding. For cost-effective and eco-friendly
EOR solutions, a biopolymer and a surfactant synthesized from Jatropha seeds are used in this
study to determine their effectiveness in increasing the oil recovery during core flooding analysis.
The experiment involved an initial water flooding that served as the base cases of three weight
percentages of polymers and polymeric surfactant solutions. The results for the polymer flooding
of 1 wt%, 1.5 wt%, and 2 wt% showed an incremental oil recovery in comparison to water flooding
of 16.8%, 17%, and 26%, while the polymeric surfactant mixtures of 5 wt% of surfactant and 1 wt%,
1.5 wt%, and 2 wt% of a polymer recorded 16.5%, 22.3%, and 28.8%, and 10 wt% of surfactant and
1 wt%, 1.5 wt%, and 2 wt% of a polymer recorded incremental oil recoveries of 20%, 32.9%, and
38.8%, respectively
Street Culture in Omo Ghetto, King of Boys, and Nimbe, Selected Nollywood Films
Get PDFIn contemporary society, the problem of street culture has been a recurring
issue. Some children or adults leave their homes to live in harsh conditions on the street, thereby imbibing behaviours that qualify as street culture. Several
studies have examined street culture from the perspective of gangsterism,
violence, and music as represented in written texts, with little attention paid to
films. Hence, this study investigated street culture in Nollywood films and its
effects on the character development of the characters played by the actors and
actresses portrayed in the films to highlight its implications for contemporary
Nigerian and wider society. The study adopted the content analytical method
in interrogating the selected films. A purposive sampling technique was used to
select three Nollywood films. The films were subjected to content and
qualitative analysis to explore the elements of street culture in them. The study
adopted Erikson’s Psychosocial Development Theory as the theoretical
framework. Findings revealed that street urchins are victims of poor parenting,
economic hardships, poverty, peer pressure, absence of a father figure, poor
societal values, the death of a parent, neglect, abandonment, physical and
emotional abuse, and violence as portrayed in the selected films. The study
found that the consequences of these factors on street urchins include
maladaptive behaviours, indiscriminate sexual practices, substance abuse,
prostitution, stealing, and pickpocketing. Further findings revealed that filmmakers deployed different narrative patterns to elucidate how the
characters develop in the films. The study, therefore, recommended that
parents should not shirk their duties towards their children and should provide
enabling environments through which the children can feel safe and repose
confidence in them. There should be a job creation and poverty alleviation
programme by the Nigerian government to reduce the number of street
urchins. The government should also censor the quality of films produced to
make them avenues for correcting societal ills