B. Dikici and I. Ozdemir
The purpose of this paper is to investigate the corrosion behaviour of ferroboron (FeB) and FeB/h‐BN (hexagonal boron nitride) coatings deposited onto A383 substrates by…
Abstract
Purpose
The purpose of this paper is to investigate the corrosion behaviour of ferroboron (FeB) and FeB/h‐BN (hexagonal boron nitride) coatings deposited onto A383 substrates by atmospheric plasma spraying.
Design/methodology/approach
Potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion susceptibilities of the composite coatings. Microstructural characterizations were carried out by using scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS).
Findings
It was observed that the coatings resisted localized corrosion in NaCl solutions and protective oxide films on the coatings repaired themselves over the corrosion potential. Hexagonal‐BN is not only a limiting factor in the corrosion of the FeB based coatings. The corrosion morphologies of the coatings are strictly dependent on pores and micro‐cracks in the coating.
Practical implications
The iron‐based borides act as solid lubricants and have a positive influence on tribological properties such as hardness, friction and corrosion of the coating.
Originality/value
Knowledge of the effects of FeB on the corrosion behaviour of thermal spray coatings is still incomplete and this is the most important obstacle to the widespread use of the coatings in engineering applications. The paper reports electrochemical test results of the coatings and discusses the morphologic effects of h‐BN on the corrosion behaviour.
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Amanda de Oliveira e Silva, Alice Leonel, Maisa Tonon Bitti Perazzini and Hugo Perazzini
Brewer's spent grain (BSG) is the main by-product of the brewing industry, holding significant potential for biomass applications. The purpose of this paper was to determine the…
Abstract
Purpose
Brewer's spent grain (BSG) is the main by-product of the brewing industry, holding significant potential for biomass applications. The purpose of this paper was to determine the effective thermal conductivity (keff) of BSG and to develop an Artificial Neural Network (ANN) to predict keff, since this property is fundamental in the design and optimization of the thermochemical conversion processes toward the feasibility of bioenergy production.
Design/methodology/approach
The experimental determination of keff as a function of BSG particle diameter and heating rate was performed using the line heat source method. The resulting values were used as a database for training the ANN and testing five multiple linear regression models to predict keff under different conditions.
Findings
Experimental values of keff were in the range of 0.090–0.127 W m−1 K−1, typical for biomasses. The results showed that the reduction of the BSG particle diameter increases keff, and that the increase in the heating rate does not statistically affect this property. The developed neural model presented superior performance to the multiple linear regression models, accurately predicting the experimental values and new patterns not addressed in the training procedure.
Originality/value
The empirical correlations and the developed ANN can be utilized in future work. This research conducted a discussion on the practical implications of the results for biomass valorization. This subject is very scarce in the literature, and no studies related to keff of BSG were found.
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Chao Han, Li Ma, Bo Jiang Ma, Guosheng Huang and Ying Xiang Ma
This paper aims to verify weather atmospheric plasma spray (APS) in situ remelting posttreatment is effective for densifying the porous FeCoCrMoCBY amorphous alloy (FAA) coating…
Abstract
Purpose
This paper aims to verify weather atmospheric plasma spray (APS) in situ remelting posttreatment is effective for densifying the porous FeCoCrMoCBY amorphous alloy (FAA) coating and improving the antiabrasion and anticorrosion performances or not.
Design/methodology/approach
APS was used to deposit and in situ densify FAA coating on the 40Cr substrate. Scanning electron microscope, X-ray diffractometer, energy dispersive spectroscopy, neutral salt spray, hardness and wear behavior test were used to evaluate the densifying effects.
Findings
APS remelting technology can effectively improve the hardness of the coating by reducing the porosity. After remelting at 30 kW power, the hardness of the coating increased by about 260 HV0.2 and the porosity decreased to 2.78%. The amorphous content of the coating is 93.9%, which is about 3.5% lower than original powders. The electrochemical impedance spectrum and neutral salt spray test results show that APS remelting can reduce the corrosion rate by about 62.7%.
Originality/value
APS remelting method is firstly proposed in this work to replace laser remelting or laser cladding methods. APS remelting method can effectively improve the corrosion and abrasion resistance of the FAA coating by increasing the densification with much low recrystallization, which is big progress for application of FAA coatings.
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Santosh Kumar, Manoj Kumar and Neeru Jindal
This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic…
Abstract
Purpose
This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic researchers working in the domain of cold gas dynamics spray coating.
Design/methodology/approach
A study on the cold spray coating is presented by summarizing the data present in literature. Important factors such as coating temperature, pressure, coating thickness, particle size, which affect the erosion-corrosion (E-C) resistance, physical and mechanical properties of boiler steel are stated. This paper also addresses the use of cold spray coating and compares it with other different thermal spray processes.
Findings
From the literature review, it was noticed that cold spray technology is best as compare to other thermal spray processes to reduce porosity, increase hardness, adhesion strength and retention in properties of feedstock powders.
Originality/value
Cold spray coating technology has a great potential in almost every field especially in restoration of surfaces, generation of complex surface, biomedical application, resist hot corrosion, wear, oxidation and erosion corrosion.
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This paper aims to investigate the structural, corrosion and the study of tribocorrosion features of the AA7075 aluminum alloy with and without the application of electroless…
Abstract
Purpose
This paper aims to investigate the structural, corrosion and the study of tribocorrosion features of the AA7075 aluminum alloy with and without the application of electroless Ni-P/Ni-B duplex coating with a thickness of approximately 40 microns.
Design/methodology/approach
Surface characterization of the samples was made by structural surveys (light optic microscope, scanning electron microscopic examinations and X-ray diffraction analyses), hardness measurements, corrosion and tribocorrosion tests.
Findings
Results of the experiments showed that upper Ni-B coating deposited on the surface of first Ni-P layer by duplex treatment caused remarkable increment in the hardness, corrosion resistance and tribocorrosion performance as compared to the AA7075 aluminum alloy.
Originality/value
This study can be a practical reference and offers insight into the effects of duplex treating on the increase of hardness, corrosion and tribocorrosion performance.
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Mehdi Ranjbar-Roeintan, Sajad Ahmadian and Ali Soleymani
The study aims to predict a low-velocity impact on a plate reinforced with carbon nanotubes (CNTs) using machine learning models.
Abstract
Purpose
The study aims to predict a low-velocity impact on a plate reinforced with carbon nanotubes (CNTs) using machine learning models.
Design/methodology/approach
The first-order shear deformation plate theory (FSDT) is used to express the plate displacements filed. The Hertz nonlinear contact law is used to predict the contact between impactor and plate. Using the energy method and Hamilton’s principle, the motion equations are extracted. The six main parameters considered as inputs to machine learning models are CNTs percentage, impactor radius, plate thickness, plate length and width, CNTs distribution profile and impactor initial velocity. These input parameters are used to predict two impact targets including contact force and contact time.
Findings
As the values of the targets are continuous, the machine learning task is considered a regression problem. Therefore, this study uses different regression models to predict the targets. These regression models include linear regression, stochastic gradient descent regressor, Bayesian regression, partial least squares regression, Gaussian process regression, multilayer perceptron regressor, support vector regression and decision tree regression. To validate the effectiveness of the regression models, experiments are designed based on different evaluation metrics. The results of the experiments demonstrate that the machine learning models achieve promising performance in predicting the contact force and contact time based on the input parameters.
Originality/value
Due to the volume of high numerical calculations of impact mechanics to reach the response, the targets of the impact problem are predicted using a variety of machine learning methods.
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Abhishek Kansal, Akshay Dvivedi and Pradeep Kumar
The purpose of this study to investigate the organized porous network zinc (OPNZ) scaffolds. Their mechanical characteristics, surface roughness and fracture mechanism were…
Abstract
Purpose
The purpose of this study to investigate the organized porous network zinc (OPNZ) scaffolds. Their mechanical characteristics, surface roughness and fracture mechanism were assessed in relation to their structural properties. The prospects of fused deposition modeling (FDM) for printing metal scaffolds via rapid tooling have also been studied.
Design/methodology/approach
Zn scaffolds with different pore and strut sizes were manufactured via the rapid tooling method. This method is a multistep process that begins with the 3D printing of a polymer template. Later, a paraffin template was obtained from the prepared polymer template. Finally, this paraffin template was used to fabricate the Zn scaffold using microwave sintering. The characterization of prepared Zn samples involved structural characterization, microstructural study, surface roughness testing and compression testing. Moreover, based on the Gibson–Ashby model analysis, the model equations’ constant values were evaluated, which can help in predicting the mechanical properties of Zn scaffolds.
Findings
The scanning electron microscopy study confirmed that the fabricated sample pores were open and interconnected. The X-ray diffraction analysis revealed that the Zn scaffold contained hexagonal closed-packed Zn peaks related to the a-Zn phase, validating that scaffolds were free from contamination and impurity. The range for ultimate compressive strength, compressive modulus and plateau stresses for Zn samples were found to be 6.75–39 MPa, 0.14–3.51 GPa and 1.85–12.6 MPa by adjusting their porosity, which are comparable with the cancellous bones. The average roughness value for the Zn scaffolds was found to be 1.86 µm.
Originality/value
This research work can widen the scope for extrusion-based FDM printers for fabricating biocompatible and biodegradable metal Zn scaffolds. This study also revealed the effects of scaffold structural properties like porosity, pore and strut size effect on their mechanical characteristics in view of tissue engineering applications.
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Zn has been attracting increasing attention with its biological compatibility property as a degradable implant material. Besides mechanical properties, especially for bone implant…
Abstract
Purpose
Zn has been attracting increasing attention with its biological compatibility property as a degradable implant material. Besides mechanical properties, especially for bone implant applications, wear resistance is a crucial mechanical property. The purpose of this study is to investigate HPTed Zn samples’ tribological behavior under dry and simulated body fluid (SBF) lubrication conditions.
Design/methodology/approach
Pure Zn powders were consolidated via the high-pressure torsion (HPT) method with 1, 5 and 10 rotations. Cast pure Zn samples were used as the control group. The wear behavior of pure Zn samples was investigated under dry and SBF lubrication conditions with a ball-on testing method. The wear tracks were observed with a mechanical profilometer and scanning electron microscope (SEM).
Findings
The application of HPT not only improved the mechanical strength and degradation performance but also improved wear resistance. However, tests with SBF resulted in higher wear rates. Besides, SBF significantly masked the positive effect of HPT on the coefficient of friction (COF). Although with SBF tests, 10 HPT rotation samples resulted in the lowest wear width and volume.
Originality/value
The main originality of this study is to reveal the HPT process and SBF effects on the tribological behavior of pure Zn to observe their potential usage for bone implant applications.
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This chapter aims to provide the recent developments on the supplementary education system in Turkey. The national examinations for advancing to higher levels of schooling are…
Abstract
Purpose
This chapter aims to provide the recent developments on the supplementary education system in Turkey. The national examinations for advancing to higher levels of schooling are believed to fuel the demand for Supplementary Education Centers (SECs). Further, we aim to understand the distribution of the SECs and of the secondary schools across the provinces of Turkey in order to evaluate the spacial equity considerations.
Design/methodology/approach
The evolution of the SECs and of the secondary schools over time are described and compared. The provincial distribution of the SECs, secondary schools, and the high school age population are compared. The characteristics of these distributions are evaluated to inform about spatial equity issues. The distribution of high school age population that attend secondary schools and the distribution of the secondary school students that attend SECs across the provinces are compared.
Findings
The evidence points out to significant provincial variations in various characteristics of SECs and the secondary schools. The distribution of the SECs is more unequal than that of the secondary schools. The provinces located mostly in the east and south east of the country have lower quality SECs and secondary schools. Further, the SEC participation among the secondary school students and the secondary school participation among the relevant age group are lower in some of the provinces indicating major disadvantages.
Originality/value
The review of the most recent developments about the SECs, examination and comparison of provincial distributions of the SECs and of the secondary schools are novelties in this chapter.
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M. Nickie Coomer and Kenzie Latham-Mintus
In this chapter, we examine the reflexive interplay of cultural, institutional, organizational, and personal narratives to examine more completely the ways in which successful and…
Abstract
Purpose
In this chapter, we examine the reflexive interplay of cultural, institutional, organizational, and personal narratives to examine more completely the ways in which successful and normative participation in schooling signals the ability and opportunity to participate in life beyond the institution.
Methods/Approach
Using narrative analysis techniques, we analyzed the interviews of eight college students who described their experiences with test anxiety.
Findings
Each individual story and experience points to the ebb and flow of participation and exclusion in the activities of schooling as well as a full participant in life more broadly. Significantly, we find that what it means to be a successful student in higher education has bearing on what it means to be a productive and worthwhile citizen, daughter, son, and partner.
Implication/Value
This research adds needed complexity to the study of test anxiety by highlighting the ways in which higher education settings rely on the medical model of disability to enact their own gatekeeping mechanisms in an effort to “legitimize” disability through acknowledgment and accommodation. Findings point to the ways in which culturally circulating stories of disability can shape organizational responses and how these can shape personal experience.