Laser power interaction effect on the evolving properties of laser metal-deposited titanium
- Authors: Nyoni, Ezekiel
- Date: 2015
- Subjects: Titanium powder , Pulsed laser deposition , Metal coating , Biomedical materials
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/58432 , uj:16450
- Description: Abstract: Titanium and its alloys are regarded as super alloys because of their ability to maintain high strength and light weight properties at elevated temperatures. Titanium has posed problems during its machining; as it always reacts with the machining tool at high temperatures, making it one of the most expensive metals to machine. It has been the interest of researchers to be able to use additive manufacturing methods in the fabrication of titanium; and the rise in the use of the Laser Metal Deposition process in the manufacturing of titanium has led to research studies in additive manufacturing. However, complex interrelationships exists between the processing parameters which lay a demand to optimise the parameters. There has also been a rise in the demand for the bone implants recently in the biomedical industry. The main implants on demand are the dental, knee and hip implants. However, the biocompatibility of the existing materials has been an issue for some time; as most of these materials become reactive in the body for long-term implantation. This has led to the development of titanium as a material for bioimplants. This research study presents a platform for analysing the laser power interaction effects on the evolving properties of commercially pure titanium during laser metal deposition tailored for biomedical applications. A set of preliminary studies was first conducted to establish the processing parameter window. A total of seven samples were fabricated by depositing titanium powder onto a Ti-6Al-4V base metal by varying the laser power from 400 to 1600 watts, whilst keeping all the other parameters constant. This was done to check how the laser power relates to the material properties of titanium; as the laser power is recognised as one of the most influential parameters on the evolving properties of laser deposited materials. The microhardness, microstructure, wear resistance and bio-compatibility tests were conducted for the material characterisation of this study. The optimized processing parameters obtained for this research study were: the spot size of 4 mm, powder flow rate of 2 rpm, gas flow rate of 2 l/min, and the scanning speed set at 0.002m/s. The microstructural evaluation revealed that the rate of dilution increased with an increase in the laser power. The increase in the dilution ratio tended to have negative effects on the wear resistance capabilities of the deposited materials. As the dilution increased, the wear resistance of the deposits decreased. This is attributed to the fact that the bond strength of the deposits decreases with an increase in the laser power. Also, the microstructural evaluation showed that finer martensitic... , M.Ing. (Mechanical Engineering)
- Full Text:
- Authors: Nyoni, Ezekiel
- Date: 2015
- Subjects: Titanium powder , Pulsed laser deposition , Metal coating , Biomedical materials
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/58432 , uj:16450
- Description: Abstract: Titanium and its alloys are regarded as super alloys because of their ability to maintain high strength and light weight properties at elevated temperatures. Titanium has posed problems during its machining; as it always reacts with the machining tool at high temperatures, making it one of the most expensive metals to machine. It has been the interest of researchers to be able to use additive manufacturing methods in the fabrication of titanium; and the rise in the use of the Laser Metal Deposition process in the manufacturing of titanium has led to research studies in additive manufacturing. However, complex interrelationships exists between the processing parameters which lay a demand to optimise the parameters. There has also been a rise in the demand for the bone implants recently in the biomedical industry. The main implants on demand are the dental, knee and hip implants. However, the biocompatibility of the existing materials has been an issue for some time; as most of these materials become reactive in the body for long-term implantation. This has led to the development of titanium as a material for bioimplants. This research study presents a platform for analysing the laser power interaction effects on the evolving properties of commercially pure titanium during laser metal deposition tailored for biomedical applications. A set of preliminary studies was first conducted to establish the processing parameter window. A total of seven samples were fabricated by depositing titanium powder onto a Ti-6Al-4V base metal by varying the laser power from 400 to 1600 watts, whilst keeping all the other parameters constant. This was done to check how the laser power relates to the material properties of titanium; as the laser power is recognised as one of the most influential parameters on the evolving properties of laser deposited materials. The microhardness, microstructure, wear resistance and bio-compatibility tests were conducted for the material characterisation of this study. The optimized processing parameters obtained for this research study were: the spot size of 4 mm, powder flow rate of 2 rpm, gas flow rate of 2 l/min, and the scanning speed set at 0.002m/s. The microstructural evaluation revealed that the rate of dilution increased with an increase in the laser power. The increase in the dilution ratio tended to have negative effects on the wear resistance capabilities of the deposited materials. As the dilution increased, the wear resistance of the deposits decreased. This is attributed to the fact that the bond strength of the deposits decreases with an increase in the laser power. Also, the microstructural evaluation showed that finer martensitic... , M.Ing. (Mechanical Engineering)
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Optimization of process parameters for sputtering of hydroxyapatite target on stainless steel
- Authors: Oladijo, Segun Stephen
- Date: 2021
- Subjects: Biomedical materials , Hydroxyapatite coating , Thin films , Steel, Stainless , Sputtering (Physics)
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/481892 , uj:43679
- Description: Abstract: Biomaterials are natural or synthetic in origin materials ‘other than drug’ or the combination of two or more materials that can be used for some period for the replacement or treatment of any organs, tissue, or body. Metallic biomaterials like titanium, stainless steel, and cobalt alloys are notable materials that are adapted and used for medical applications purpose due to their favorable properties such as toughness, relatively low rate of corrosion, and excellent strength. Biomaterials are essential for the replacement of human joints and requires a long period of time such as 15 years to 20 years for older ages and more than 25 years above for younger age patients to serve as implant in their body and therefore, it is necessary to prolong the service life of biomaterials. In this study, the surface modification process was used for the enhancement of existing materials to improve the surface properties of the samples. For this research work, radio-frequency magnetron sputtering was considered for the deposition of the Hydroxyapatite (HAP) thin-film coating on stainless steel. This is due to its potential surface modification capability of high deposition rate, strong bond affinity, low cost of production, and capability to deposit insulating materials since Hydroxyapatite is known to be a good reinforcement for surface modification due to its favorable properties such as excellent bioactive and biocompatibility. Therefore, RF- magnetron sputtering was used for the deposition of a nanostructured thin film of Hydroxyapatite ceramic on the surface of stainless steel AISI 304. The RF sputtering process parameters (such as the RF-power and the deposition time in the deposition process) were characterized/optimized by Taguchi analysis, and evaluating the thin film phases and wear resistance, and the corrosion resistance was determined by electrochemical techniques. The scanning electron microscope (SEM) equipped with electron discharge microscopy, the atomic force microscope (AFM), X-ray diffraction, and optical microscopy were used to characterize the properties of the HAP thin-film coatings. The mechanical property and the tribological properties of the HAP coating were measured using Vickers hardness and, micro scratch tester. The electrochemical corrosion technique was used to analyze the corrosion behavior of the thin film. Whilst optimization of the process parameter was carried out using L9 Taguchi orthogonal array... , M.Ing. (Mechanical Engineering)
- Full Text:
- Authors: Oladijo, Segun Stephen
- Date: 2021
- Subjects: Biomedical materials , Hydroxyapatite coating , Thin films , Steel, Stainless , Sputtering (Physics)
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/481892 , uj:43679
- Description: Abstract: Biomaterials are natural or synthetic in origin materials ‘other than drug’ or the combination of two or more materials that can be used for some period for the replacement or treatment of any organs, tissue, or body. Metallic biomaterials like titanium, stainless steel, and cobalt alloys are notable materials that are adapted and used for medical applications purpose due to their favorable properties such as toughness, relatively low rate of corrosion, and excellent strength. Biomaterials are essential for the replacement of human joints and requires a long period of time such as 15 years to 20 years for older ages and more than 25 years above for younger age patients to serve as implant in their body and therefore, it is necessary to prolong the service life of biomaterials. In this study, the surface modification process was used for the enhancement of existing materials to improve the surface properties of the samples. For this research work, radio-frequency magnetron sputtering was considered for the deposition of the Hydroxyapatite (HAP) thin-film coating on stainless steel. This is due to its potential surface modification capability of high deposition rate, strong bond affinity, low cost of production, and capability to deposit insulating materials since Hydroxyapatite is known to be a good reinforcement for surface modification due to its favorable properties such as excellent bioactive and biocompatibility. Therefore, RF- magnetron sputtering was used for the deposition of a nanostructured thin film of Hydroxyapatite ceramic on the surface of stainless steel AISI 304. The RF sputtering process parameters (such as the RF-power and the deposition time in the deposition process) were characterized/optimized by Taguchi analysis, and evaluating the thin film phases and wear resistance, and the corrosion resistance was determined by electrochemical techniques. The scanning electron microscope (SEM) equipped with electron discharge microscopy, the atomic force microscope (AFM), X-ray diffraction, and optical microscopy were used to characterize the properties of the HAP thin-film coatings. The mechanical property and the tribological properties of the HAP coating were measured using Vickers hardness and, micro scratch tester. The electrochemical corrosion technique was used to analyze the corrosion behavior of the thin film. Whilst optimization of the process parameter was carried out using L9 Taguchi orthogonal array... , M.Ing. (Mechanical Engineering)
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