Tawanda Marazani - Academia.edu (original) (raw)

Papers by Tawanda Marazani

Research paper thumbnail of Advancing the hydrogen production economy: A comprehensive review of technologies, sustainability, and future prospects

International journal of hydrogen energy, Aug 1, 2024

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Research paper thumbnail of Impact behavior of spark plasma sintered Ti–Al–Mo/TiN composites: a finite element analysis approach using Abaqus CAE

Beni-Seuf University Journal of Basic and Applied Sciences /Beni-Suef University Journal of Basic and Applied Sciences, Feb 22, 2024

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Research paper thumbnail of Investigation of the Parameters Governing the Performance of Jet Impingement Quick Food Freezing and Cooling Systems – A Review

Procedia Manufacturing, 2017

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Research paper thumbnail of Reduction of Excessive Flash in Friction Stir Processing of AA1100: An Experimental Observation Study

Advances in Material Sciences and Engineering, 2019

Friction stir processing (FSP) has proven to be a powerful emerging surface engineering technolog... more Friction stir processing (FSP) has proven to be a powerful emerging surface engineering technology for modifying metal surfaces and their bulk properties to desired forms. As a variant of friction stir welding (FSW), FSP borrows its principles of functionality from FSW. FSP technology is highly dependent on careful selection of process parameters. Its key parameters include tool rotational speed, traverse speed, tool tilt angles, axial force, tool and process design as well as base metal properties. Formation of excessive flash is a common FSP parametric challenge which needs to be studied. In this work, build-up of mass flash was experimentally observed and controlled by varying process tool tilt angle and the rotational during FSP of AA1100. The process was conducted using H13 tool steel cylindrical tool with a shoulder diameter of 21 mm with a 7 mm cylindrical threaded pin, at constant traverse speed of 20 mm/min at tilt angles varying from 0° to 3°, rotational speeds of 500 to 1...

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Research paper thumbnail of Microstructural, elemental, mechanical and structural attributes of AA1100/17-4 PH stainless steel composites fabricated via friction stir processing

A 100% overlap double pass friction stir process technique was developed for the fabrication of A... more A 100% overlap double pass friction stir process technique was developed for the fabrication of AA1100/17-4 PH stainless steel composites, using an H13 tool steel cylindrical threaded pin with shoulder diameter of 21 mm, pin diameter of 7 mm and pin height of 5 mm. Grooves of 2 mm width and 3.5 mm depth were machined on the 6 mm thick AA1100 plate, where the 17-4 PH stainless steel powder was packed and compacted using a pinless tool. Friction stir processing was conducted at rotational speeds of 2100, 2450 and 2800 rpm, while the travel speed of 20 mm/min, tilt angle of 2.5° and plunge depth of 0.2 mm, were kept constant. Investigations were carried out on the microstructure, elemental composition, and tensile testing and microhardness as well as structural analysis using X-ray diffraction. Defect-free micrographs with good mechanical and metallurgical connections were obtained from all the employed process parameters. However, agglomeration of reinforcements became noticeable at 2...

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Research paper thumbnail of Laser Re-Melt Technique for Laser Additive Repair of Narrow Rectangular Cracks in Grade 5 Titanium Alloy (Ti-6Al-4V)

Key Engineering Materials, 2019

Groove inaccessibility, top groove powder impedance, irregular sidewall powder delivery and lack ... more Groove inaccessibility, top groove powder impedance, irregular sidewall powder delivery and lack of sidewall vertical irradiation have been reported as major limitations for the use of Laser Additive Technology (LAT) for narrow rectangular crack repair applications. As a result, most reported repair attempts were concluded unsuccessful. In the present work, a multi-track laser re-melt technique was developed for the repair of narrow rectangular cracks of sizes 2 and 3 mm, both 5 mm deep on 7 mm thick Ti-6Al-4V plates. The laser re-melt technique was carried out at controlled laser power, focal length, spot size, powder feed rate, gas flow rate and scanning speed. The repaired substrates were evaluated for defects through optical microscopy (OM) and scanning electron microscopy (SEM). The obtained results showed densely fused defect-free repaired substrates with good evolving microstructure.

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Research paper thumbnail of Additive Manufacturing for Crack Repair Applications in Metals

Additive Manufacturing Technologies From an Optimization Perspective

Additive manufacturing (AM) builds intricate parts from 3D CAD model data in successive layers. A... more Additive manufacturing (AM) builds intricate parts from 3D CAD model data in successive layers. AM offers several advantages and has become a preferred freeform fabrication, processing, manufacturing, maintenance, and repair technique for metals, thermoplastics, ceramics, and composites. When using laser, it bears several names, which include laser additive manufacturing, laser additive technology, laser metal deposition, laser engineered net shape, direct metal deposition, and laser solid forming. These technologies use a laser beam to locally melt the powder or wire and the substrate that fuse upon solidification. AM is mainly applied in the aerospace and biomedical industries. Titanium (Ti) alloys offer very attractive properties much needed in these industries. This chapter explores AM applications for crack repairs in Ti alloys. Metal cracking industrial challenges, crack detection and repair methods, challenges, and milestones for AM repair of cracks in Ti alloys are also disc...

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Research paper thumbnail of Repair of Cracks in Metals: A Review

Procedia Manufacturing, 2017

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Research paper thumbnail of Microhardness profiling of Ti-6Al-4V components repaired through multiple laser additive re-melt technique

Procedia Manufacturing

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Research paper thumbnail of Repair of cracks in metals: A review Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing

14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Mar 20, 2017

Cracks are surface or subsurface fissures that develop in a material. Propagation energy derived ... more Cracks are surface or subsurface fissures that develop in a material. Propagation energy derived from mechanical, thermal, chemical, and metallurgical effects, or a combination of these may influence crack initiation and growth. Various types of cracks exist in metals and can be categorised as cooling, solidification, centreline, crater, grinding, pickling, heat treatment, machining tears, plating, fatigue, creep, stress corrosion and hydrogen cracks. Cracks can grow and lead to complete fracture of the component posing significant threats to component life and may lead to serious injuries or loss of life. Brittle fracture in metals occurs with little or no visible warning. Discovery of any cracks warrants immediate interventions to arrest the cracks before they propagate to the point of fracture. Several crack detection and repair methods in metals have been developed, characterised and validated through research. This paper reviews the repair techniques of cracks in metals.

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Research paper thumbnail of Investigation of the parameters governing the performance of jet impingement quick food freezing and cooling systems – a review Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing

14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016,, Mar 20, 2017

Jet Impingement Technology (JIT) is a heat transfer enhancement technique. Available literature s... more Jet Impingement Technology (JIT) is a heat transfer enhancement technique. Available literature soundly confirm its wide applications in the cooling of combustion chambers, critical parts of turbines, glass technology, electronic components, drying of paper and textile materials, drying of biomaterials and food preservation. The technology has interesting fluid dynamics and heat transfer properties. Its relative simplicity and low cost, abundance of air, generation of high heat transfer and faster freezing rates have made it a subject of extensive investigations. Several investigations on jet impingement quick food freezing and cooling systems which range from visualization, experimental, computational simulations and or numerical analysis, factorial and mathematical models have been studied. This paper reviews the governing parameters of the jet impingement quick food freezing and cooling systems.

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Research paper thumbnail of Laser additive manufacturing technology for crack repairs in titanium alloy components (2).pdf

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Research paper thumbnail of Advancing the hydrogen production economy: A comprehensive review of technologies, sustainability, and future prospects

International journal of hydrogen energy, Aug 1, 2024

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Research paper thumbnail of Impact behavior of spark plasma sintered Ti–Al–Mo/TiN composites: a finite element analysis approach using Abaqus CAE

Beni-Seuf University Journal of Basic and Applied Sciences /Beni-Suef University Journal of Basic and Applied Sciences, Feb 22, 2024

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Research paper thumbnail of Investigation of the Parameters Governing the Performance of Jet Impingement Quick Food Freezing and Cooling Systems – A Review

Procedia Manufacturing, 2017

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Research paper thumbnail of Reduction of Excessive Flash in Friction Stir Processing of AA1100: An Experimental Observation Study

Advances in Material Sciences and Engineering, 2019

Friction stir processing (FSP) has proven to be a powerful emerging surface engineering technolog... more Friction stir processing (FSP) has proven to be a powerful emerging surface engineering technology for modifying metal surfaces and their bulk properties to desired forms. As a variant of friction stir welding (FSW), FSP borrows its principles of functionality from FSW. FSP technology is highly dependent on careful selection of process parameters. Its key parameters include tool rotational speed, traverse speed, tool tilt angles, axial force, tool and process design as well as base metal properties. Formation of excessive flash is a common FSP parametric challenge which needs to be studied. In this work, build-up of mass flash was experimentally observed and controlled by varying process tool tilt angle and the rotational during FSP of AA1100. The process was conducted using H13 tool steel cylindrical tool with a shoulder diameter of 21 mm with a 7 mm cylindrical threaded pin, at constant traverse speed of 20 mm/min at tilt angles varying from 0° to 3°, rotational speeds of 500 to 1...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Microstructural, elemental, mechanical and structural attributes of AA1100/17-4 PH stainless steel composites fabricated via friction stir processing

A 100% overlap double pass friction stir process technique was developed for the fabrication of A... more A 100% overlap double pass friction stir process technique was developed for the fabrication of AA1100/17-4 PH stainless steel composites, using an H13 tool steel cylindrical threaded pin with shoulder diameter of 21 mm, pin diameter of 7 mm and pin height of 5 mm. Grooves of 2 mm width and 3.5 mm depth were machined on the 6 mm thick AA1100 plate, where the 17-4 PH stainless steel powder was packed and compacted using a pinless tool. Friction stir processing was conducted at rotational speeds of 2100, 2450 and 2800 rpm, while the travel speed of 20 mm/min, tilt angle of 2.5° and plunge depth of 0.2 mm, were kept constant. Investigations were carried out on the microstructure, elemental composition, and tensile testing and microhardness as well as structural analysis using X-ray diffraction. Defect-free micrographs with good mechanical and metallurgical connections were obtained from all the employed process parameters. However, agglomeration of reinforcements became noticeable at 2...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Laser Re-Melt Technique for Laser Additive Repair of Narrow Rectangular Cracks in Grade 5 Titanium Alloy (Ti-6Al-4V)

Key Engineering Materials, 2019

Groove inaccessibility, top groove powder impedance, irregular sidewall powder delivery and lack ... more Groove inaccessibility, top groove powder impedance, irregular sidewall powder delivery and lack of sidewall vertical irradiation have been reported as major limitations for the use of Laser Additive Technology (LAT) for narrow rectangular crack repair applications. As a result, most reported repair attempts were concluded unsuccessful. In the present work, a multi-track laser re-melt technique was developed for the repair of narrow rectangular cracks of sizes 2 and 3 mm, both 5 mm deep on 7 mm thick Ti-6Al-4V plates. The laser re-melt technique was carried out at controlled laser power, focal length, spot size, powder feed rate, gas flow rate and scanning speed. The repaired substrates were evaluated for defects through optical microscopy (OM) and scanning electron microscopy (SEM). The obtained results showed densely fused defect-free repaired substrates with good evolving microstructure.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Additive Manufacturing for Crack Repair Applications in Metals

Additive Manufacturing Technologies From an Optimization Perspective

Additive manufacturing (AM) builds intricate parts from 3D CAD model data in successive layers. A... more Additive manufacturing (AM) builds intricate parts from 3D CAD model data in successive layers. AM offers several advantages and has become a preferred freeform fabrication, processing, manufacturing, maintenance, and repair technique for metals, thermoplastics, ceramics, and composites. When using laser, it bears several names, which include laser additive manufacturing, laser additive technology, laser metal deposition, laser engineered net shape, direct metal deposition, and laser solid forming. These technologies use a laser beam to locally melt the powder or wire and the substrate that fuse upon solidification. AM is mainly applied in the aerospace and biomedical industries. Titanium (Ti) alloys offer very attractive properties much needed in these industries. This chapter explores AM applications for crack repairs in Ti alloys. Metal cracking industrial challenges, crack detection and repair methods, challenges, and milestones for AM repair of cracks in Ti alloys are also disc...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Repair of Cracks in Metals: A Review

Procedia Manufacturing, 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Microhardness profiling of Ti-6Al-4V components repaired through multiple laser additive re-melt technique

Procedia Manufacturing

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Repair of cracks in metals: A review Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing

14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Mar 20, 2017

Cracks are surface or subsurface fissures that develop in a material. Propagation energy derived ... more Cracks are surface or subsurface fissures that develop in a material. Propagation energy derived from mechanical, thermal, chemical, and metallurgical effects, or a combination of these may influence crack initiation and growth. Various types of cracks exist in metals and can be categorised as cooling, solidification, centreline, crater, grinding, pickling, heat treatment, machining tears, plating, fatigue, creep, stress corrosion and hydrogen cracks. Cracks can grow and lead to complete fracture of the component posing significant threats to component life and may lead to serious injuries or loss of life. Brittle fracture in metals occurs with little or no visible warning. Discovery of any cracks warrants immediate interventions to arrest the cracks before they propagate to the point of fracture. Several crack detection and repair methods in metals have been developed, characterised and validated through research. This paper reviews the repair techniques of cracks in metals.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Investigation of the parameters governing the performance of jet impingement quick food freezing and cooling systems – a review Peer-review under responsibility of the organizing committee of the 14th Global Conference on Sustainable Manufacturing

14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016,, Mar 20, 2017

Jet Impingement Technology (JIT) is a heat transfer enhancement technique. Available literature s... more Jet Impingement Technology (JIT) is a heat transfer enhancement technique. Available literature soundly confirm its wide applications in the cooling of combustion chambers, critical parts of turbines, glass technology, electronic components, drying of paper and textile materials, drying of biomaterials and food preservation. The technology has interesting fluid dynamics and heat transfer properties. Its relative simplicity and low cost, abundance of air, generation of high heat transfer and faster freezing rates have made it a subject of extensive investigations. Several investigations on jet impingement quick food freezing and cooling systems which range from visualization, experimental, computational simulations and or numerical analysis, factorial and mathematical models have been studied. This paper reviews the governing parameters of the jet impingement quick food freezing and cooling systems.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Laser additive manufacturing technology for crack repairs in titanium alloy components (2).pdf

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