Advanced material development : functionally graded stainless steel alloy composites
- Authors: Bayode, A.
- Date: 2018
- Subjects: Metallic composites , Metal coating , Pulsed laser deposition
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/284879 , uj:30784
- Description: D.Ing. (Mechanical Engineering) , Abstract: Laser metal deposition (LMD) is one of the additive manufacturing technologies that is used in the production of fully dense parts layer by layer. This innovative manufacturing process shows real promise in reducing component fabrication time, cost and weight. One of the major advantages of this technology is in the ability to manufacture components with multi-material properties such as Functionally Graded Materials (FGM). FGM is a class of advanced materials that combine the benefits of its component materials together as a whole, while minimizing the problems produced by material property mismatch of the constituent materials. Several studies have been conducted on FGMs processed by LMD. Most of these studies are on metal-ceramic composites, however, there is a growing need for bimetallic components with different properties along their axial or radial directions for modern engineering applications. In this study, the laser metal deposition process was evaluated as a candidate for manufacturing a compositionally graded bimetal material consisting magnetic and non-magnetic metals. The materials used were 17-4PH powder, AISI 316L powder and AISI 316 substrate. Since this study has not been done and there were no known models or strategies to follow in building this particular FGM. Trial and error experiments were first adopted in selecting the process conditions for building the FGM. The trial and error experiments, referred to as preliminary study involved the production of 17- 4PH and AISI 316L clads. This was done primarily to evaluate the solidification behaviour of the individual powders and also identify the process window that will successfully produce fully dense clads with good bonding and wettability that are structurally harmonised. Based on the findings of the preliminary studies, a set of parameters was obtained as a standard for producing the compositionally graded composite...
- Full Text:
- Authors: Bayode, A.
- Date: 2018
- Subjects: Metallic composites , Metal coating , Pulsed laser deposition
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/284879 , uj:30784
- Description: D.Ing. (Mechanical Engineering) , Abstract: Laser metal deposition (LMD) is one of the additive manufacturing technologies that is used in the production of fully dense parts layer by layer. This innovative manufacturing process shows real promise in reducing component fabrication time, cost and weight. One of the major advantages of this technology is in the ability to manufacture components with multi-material properties such as Functionally Graded Materials (FGM). FGM is a class of advanced materials that combine the benefits of its component materials together as a whole, while minimizing the problems produced by material property mismatch of the constituent materials. Several studies have been conducted on FGMs processed by LMD. Most of these studies are on metal-ceramic composites, however, there is a growing need for bimetallic components with different properties along their axial or radial directions for modern engineering applications. In this study, the laser metal deposition process was evaluated as a candidate for manufacturing a compositionally graded bimetal material consisting magnetic and non-magnetic metals. The materials used were 17-4PH powder, AISI 316L powder and AISI 316 substrate. Since this study has not been done and there were no known models or strategies to follow in building this particular FGM. Trial and error experiments were first adopted in selecting the process conditions for building the FGM. The trial and error experiments, referred to as preliminary study involved the production of 17- 4PH and AISI 316L clads. This was done primarily to evaluate the solidification behaviour of the individual powders and also identify the process window that will successfully produce fully dense clads with good bonding and wettability that are structurally harmonised. Based on the findings of the preliminary studies, a set of parameters was obtained as a standard for producing the compositionally graded composite...
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Development of TI6AL4V based metal matrix hybrid composites using laser metal deposition
- Authors: Ochonogor, Onyeka Franklin
- Date: 2018
- Subjects: Titanium-aluminum-vanadium alloys , Metallic composites , Metals - Mechanical properties
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/285978 , uj:30936
- Description: D.Phil. (Mechanical Engineering) , Abstract: Three alloy particles; Ti6Al4V alloy, Boron Nitride (BN) and Boron Carbide (B4C) particle were compacted and deposited to the surface of Ti6Al4V alloy substrate using laser metal deposition, an advance additive manufacturing laser technology system attached with three hopper feeders for powder delivery to form a hybrid metal matrix composite. The high demand for improved properties of Ti6Al4V alloy metal matrix composites has led to the fabrication of Ti6Al4V metal with good hardness and most importanly for wear application. Combined properties of Ti6Al4V alloy, Boron Nitride (BN) and Boron Carbide (B4C) particles with unique mechanical properties may result in enhancing the resistance to matrix cracking and the forming of a Ti6Al4V metal - matrix hybrid composite. The combination of three different reinforcement powder particles is often very difficult due to extreme hardness property that often affects the homogenization and bonding mechanism, yet such hybrid composites has a number of benefits in service. However, good combination of properties was possible with the aid of an Nd: YAG laser system attached with three hopper system that delivered powder particles into the melt pool created on the surface of the substrate. Boron carbide / nitride additions were less than 10 volume percent with Ti6Al4V alloy powder having more than 90 volume percent to enable grain growth control, which resulted in good metallurgical bonding in the composites. Double tracked Ti6Al4V - BN - B4C composites were fabricated at different laser power and composition / variations, which were used to form the basis for the experiments. Ten samples were fabricated using laser power ranging between 1700 W and 2800 W while the scanning speed was kept constant at 1.0 m/min. This project however focused on Ti6Al4V - BN - B4C powder coatings on titanium alloy substrate at different process parameters. Optimized samples were therefore cut to experimental sizes and the effect of laser power on the deposition process and powder flow rate were investigated. The resultant microstructures revealed an excellent and homogeneous distribution of the martensitic metal matrix composite structure (MMCs). The Ti6Al4V - BN - B4C composites were crack and pore free, with enabling phase transformation in the martensites. The optimized samples were selected for 2000 W and 1400 W due to good surface integrity, absence of porosity good metallurgical and mechanical properties such as fine grain structure with excellent bonding strength...
- Full Text:
- Authors: Ochonogor, Onyeka Franklin
- Date: 2018
- Subjects: Titanium-aluminum-vanadium alloys , Metallic composites , Metals - Mechanical properties
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/285978 , uj:30936
- Description: D.Phil. (Mechanical Engineering) , Abstract: Three alloy particles; Ti6Al4V alloy, Boron Nitride (BN) and Boron Carbide (B4C) particle were compacted and deposited to the surface of Ti6Al4V alloy substrate using laser metal deposition, an advance additive manufacturing laser technology system attached with three hopper feeders for powder delivery to form a hybrid metal matrix composite. The high demand for improved properties of Ti6Al4V alloy metal matrix composites has led to the fabrication of Ti6Al4V metal with good hardness and most importanly for wear application. Combined properties of Ti6Al4V alloy, Boron Nitride (BN) and Boron Carbide (B4C) particles with unique mechanical properties may result in enhancing the resistance to matrix cracking and the forming of a Ti6Al4V metal - matrix hybrid composite. The combination of three different reinforcement powder particles is often very difficult due to extreme hardness property that often affects the homogenization and bonding mechanism, yet such hybrid composites has a number of benefits in service. However, good combination of properties was possible with the aid of an Nd: YAG laser system attached with three hopper system that delivered powder particles into the melt pool created on the surface of the substrate. Boron carbide / nitride additions were less than 10 volume percent with Ti6Al4V alloy powder having more than 90 volume percent to enable grain growth control, which resulted in good metallurgical bonding in the composites. Double tracked Ti6Al4V - BN - B4C composites were fabricated at different laser power and composition / variations, which were used to form the basis for the experiments. Ten samples were fabricated using laser power ranging between 1700 W and 2800 W while the scanning speed was kept constant at 1.0 m/min. This project however focused on Ti6Al4V - BN - B4C powder coatings on titanium alloy substrate at different process parameters. Optimized samples were therefore cut to experimental sizes and the effect of laser power on the deposition process and powder flow rate were investigated. The resultant microstructures revealed an excellent and homogeneous distribution of the martensitic metal matrix composite structure (MMCs). The Ti6Al4V - BN - B4C composites were crack and pore free, with enabling phase transformation in the martensites. The optimized samples were selected for 2000 W and 1400 W due to good surface integrity, absence of porosity good metallurgical and mechanical properties such as fine grain structure with excellent bonding strength...
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Feasibility of manufacturing ceramic based metal matrix composites (MMC) for multi-purpose industrial application
- Authors: Madzivhandila, Takalani
- Date: 2012-11-02
- Subjects: Ceramic-matrix composites , Metallic composites , Ceramic fibers
- Type: Thesis
- Identifier: uj:7294 , http://hdl.handle.net/10210/8034
- Description: M.Tech. , The mining industry exerts ever increasing demand for components with high wear resistance to the extent that plain ferrous alloys are falling short. Innovative metal-matrix composites nonferrous metals have been widely researched and used. Casting composites based on ferrous alloys pose monumental challenges in casting. Firstly, the density differential results in large resistant forces on the ceramic such that unless a rigid structure is configured, the less dense ceramic floats on the metal stream. Secondly, the poor wetting properties between metal and ceramic will result in inferior bonding of the matrix, hence separation of solids in service.This study presents the feasibility of manufacturing ceramic based metal matrix composites (MMC) for multi-purpose industrial application including wettability and the bonding between the matrix and the composite. The cold rods of alumina positioned in the mould prior to casting cracked as soon as they came in contact with hot metal. Because of the density difference between ceramic and liquid metal the alumina tended to float under the influence of Ferro static pressure. Infiltration of zirconia (ZrO2) and alumina (Al2O3) in ferrous matrix was investigated. Infiltration of liquid metal in ceramic filters increased with porosity of filters i.e. greater infiltration occurred in filters with larger pore volume fraction measured in terms of number of pores per linear inch (ppi). Thus, there was high infiltration in casting with 10ppi followed by 30ppi and there was poor infiltration in 50ppi ceramics. Infiltration increased with increasing temperature of the ceramics. A temperature of 1000oC was found to be superior to 800oC. The wetting behaviour of molten iron on the substrates of Al2O3 was investigated. Titanium in high chromium white cast iron was found to improve the wetting characteristics on alumina. The wetting angle decreased with increased titanium content. The wear properties of ferrous alloys used were not significantly improved by the ceramic used to make the composite. Filters are produced by a deposition process and hence are not densified for the purpose of manufacturing hard composites
- Full Text:
- Authors: Madzivhandila, Takalani
- Date: 2012-11-02
- Subjects: Ceramic-matrix composites , Metallic composites , Ceramic fibers
- Type: Thesis
- Identifier: uj:7294 , http://hdl.handle.net/10210/8034
- Description: M.Tech. , The mining industry exerts ever increasing demand for components with high wear resistance to the extent that plain ferrous alloys are falling short. Innovative metal-matrix composites nonferrous metals have been widely researched and used. Casting composites based on ferrous alloys pose monumental challenges in casting. Firstly, the density differential results in large resistant forces on the ceramic such that unless a rigid structure is configured, the less dense ceramic floats on the metal stream. Secondly, the poor wetting properties between metal and ceramic will result in inferior bonding of the matrix, hence separation of solids in service.This study presents the feasibility of manufacturing ceramic based metal matrix composites (MMC) for multi-purpose industrial application including wettability and the bonding between the matrix and the composite. The cold rods of alumina positioned in the mould prior to casting cracked as soon as they came in contact with hot metal. Because of the density difference between ceramic and liquid metal the alumina tended to float under the influence of Ferro static pressure. Infiltration of zirconia (ZrO2) and alumina (Al2O3) in ferrous matrix was investigated. Infiltration of liquid metal in ceramic filters increased with porosity of filters i.e. greater infiltration occurred in filters with larger pore volume fraction measured in terms of number of pores per linear inch (ppi). Thus, there was high infiltration in casting with 10ppi followed by 30ppi and there was poor infiltration in 50ppi ceramics. Infiltration increased with increasing temperature of the ceramics. A temperature of 1000oC was found to be superior to 800oC. The wetting behaviour of molten iron on the substrates of Al2O3 was investigated. Titanium in high chromium white cast iron was found to improve the wetting characteristics on alumina. The wetting angle decreased with increased titanium content. The wear properties of ferrous alloys used were not significantly improved by the ceramic used to make the composite. Filters are produced by a deposition process and hence are not densified for the purpose of manufacturing hard composites
- Full Text:
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