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Article
Publication date: 13 September 2022

Modupeola Dada, Patricia Popoola, Ntombi Mathe, Sisa Pityana and Samson Adeosun

In this study, AlCoCrFeNi–Cu (Cu-based) and AlCoCrFeNi–Ti (Ti-based) high entropy alloys (HEAs) were fabricated using a direct blown powder technique via laser additive…

760

Abstract

Purpose

In this study, AlCoCrFeNi–Cu (Cu-based) and AlCoCrFeNi–Ti (Ti-based) high entropy alloys (HEAs) were fabricated using a direct blown powder technique via laser additive manufacturing on an A301 steel baseplate for aerospace applications. The purpose of this research is to investigate the electrical resistivity and oxidation behavior of the as-built copper (Cu)- and titanium (Ti)-based alloys and to understand the alloying effect, the HEAs core effects and the influence of laser parameters on the physical properties of the alloys.

Design/methodology/approach

The as-received AlCoCrFeNiCu and AlCoCrFeNiTi powders were used to fabricate HEA clads on an A301 steel baseplate preheated at 400°C using a 3 kW Rofin Sinar dY044 continuous-wave laser-deposition system fitted with a KUKA robotic arm. The deposits were sectioned using an electric cutting machine and prepared by standard metallographic methods to investigate the electrical and oxidation properties of the alloys.

Findings

The results showed that the laser power had the most influence on the physical properties of the alloys. The Ti-based alloy had better resistivity than the Cu-based alloy, whereas the Cu-based alloy had better oxidation residence than the Ti-based alloy which attributed to the compositional alloying effect (Cu, aluminum and nickel) and the orderliness of the lattice, which is significantly associated with the electron transportation; consequently, the more distorted the lattice, the easier the transportation of electrons and the better the properties of the HEAs.

Originality/value

It is evident from the studies that the composition of HEAs and the laser processing parameters are two significant factors that influence the physical properties of laser deposited HEAs for aerospace applications.

Details

World Journal of Engineering, vol. 20 no. 5
Type: Research Article
ISSN: 1708-5284

Keywords

Available. Content available
Article
Publication date: 2 August 2021

Modupeola Dada, Patricia Popoola and Ntombi Mathe

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential…

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Abstract

Purpose

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined.

Design/methodology/approach

Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials.

Findings

HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA.

Research limitations/implications

The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages.

Originality/value

It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.

Details

World Journal of Engineering, vol. 20 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 5 March 2018

Ayomide Osundare, Daniel Toyin Oloruntoba and Patricia Popoola

The purpose of this paper is to develop technically efficient and economically effective sacrificial anodes that can be used for cathodic protection (CP) of pipelines in marine…

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Abstract

Purpose

The purpose of this paper is to develop technically efficient and economically effective sacrificial anodes that can be used for cathodic protection (CP) of pipelines in marine environment and fill the knowledge gap in the use of carbon anodes for CP.

Design/methodology/approach

A sacrificial anode was produced via sand casting by adding varying weight-percent of coal and ferrosilicon to a constant weight-percent of grey cast iron. The hardness of the produced anodes was evaluated using a Rockwell hardness tester. The microstructure of the anodes was observed with scanning electron microscope/energy-dispersive spectroscopy (SEM/EDS). X-ray diffraction (XRD) was used to study the phases present. A potentiostat was used to assess the corrosion behaviour of the produced anodes and mild steel in 3.5 Wt.% NaCl solution.

Findings

The SEM results showed that some anodes had interdendritic graphite formation, while others had pronounced graphite flakes. The EDS analysis showed carbon and iron to be the prominent elements in the anode. Anodes Bc, B2 and B5 with a corrosion rate of two order of magnitudes were observed to have similar dendritic structures. Anode B4 is the most electronegative with an Ecorr of −670.274 mV Ag/AgCl and a corrosion rate of 0.052475 mmpy. The produced anodes can be used to protect mild steel in the same environment owing to their lower Ecorr values compared to that of mild steel −540.907 mV Ag/AgCl.

Originality/value

Alloying has been majorly used to improve the efficiency of sacrificial anodes and to alleviate its setbacks. However, development of more technically efficient and economically effective sacrificial anodes via production of composite has not been exhaustively considered. Hence, this research focuses on the development of a carbon based anode by adding natural occurring coal and ferrosilicon to grey cast iron. The corrosion behaviour of the produced anode was evaluated and compared to that of mild steel in marine environment.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 14 November 2017

Tochukwu Victor Nwankwo, Chika Patricia Ike and Chinedu Obinna Anozie

The purpose of this paper is to examine the concept of mentoring of young librarians in South East Nigeria so as to improve their research and scholarly publications.

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Abstract

Purpose

The purpose of this paper is to examine the concept of mentoring of young librarians in South East Nigeria so as to improve their research and scholarly publications.

Design/methodology/approach

The study confined its scope to 135 librarians in the five different federal universities in South East Nigeria. In all, 100 (80 percent) of the librarians were sampled. The instrument for data collection was questionnaire which contained 30 items derived from the research questions. The descriptive survey research design was used as research method. Librarians were grouped into young librarians (assistant librarian and librarian II) and higher librarians (librarian I, senior librarian, principal librarian, deputy university librarian and university librarian); for a comprehensive analysis of the study.

Findings

The findings of the study among others reveals that young librarians are a bit knowledgeable and conversant about the term “mentoring” but not equitable when compared to that of other higher librarians in matters of scholarly publication. Also there is evidence of mentoring in place in these libraries for boosting the research prowess of librarians, but in an informal form. The librarians believed that most times the mentee’s inability to open up during interaction, and unconstructive criticisms from mentors to their mentees; are serious challenges to successful mentoring for improved scholarly publications.

Originality/value

Research studies focusing on mentoring young librarians on research and scholarly publications in Nigeria, are rare. Furthermore, librarians are not conversant with the concept of mentoring and which mentoring practices and programs are currently in place in their libraries to boost their research prowess. Also, adopting a mentor and what to expect from both mentors and mentees concerning research publications are salient areas explored in the work. This study will raise important issues that relate to research publications of both librarians and other academic researchers especially in this research impact-factor driven world of ours.

Details

Library Management, vol. 38 no. 8/9
Type: Research Article
ISSN: 0143-5124

Keywords

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Book part
Publication date: 19 September 2022

Abstract

Details

COVID-19 and the Media in Sub-Saharan Africa: Media Viability, Framing and Health Communication
Type: Book
ISBN: 978-1-80382-272-3

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Article
Publication date: 1 February 1994

Hannelore B. Rader

The following is an annotated list of materials dealing with information literacy including instruction in the use of information resources, research, and computer skills related…

72

Abstract

The following is an annotated list of materials dealing with information literacy including instruction in the use of information resources, research, and computer skills related to retrieving, using, and evaluating information. This review, the nineteenth to be published in Reference Services Review, includes items in English published in 1992. A few are not annotated because the compiler could not obtain copies of them for this review.

Details

Reference Services Review, vol. 22 no. 2
Type: Research Article
ISSN: 0090-7324

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