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https://ptsldigital.ukm.my/jspui/handle/123456789/487208Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Mariyam Jameelah Ghazali, Prof. Dr. | - |
| dc.contributor.author | Ahmad Afiq Fauzi (P94821) | - |
| dc.date.accessioned | 2023-10-11T02:30:25Z | - |
| dc.date.available | 2023-10-11T02:30:25Z | - |
| dc.date.issued | 2021-09-29 | - |
| dc.identifier.other | ukmvital:125311 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/487208 | - |
| dc.description | Nickel- based superalloys like Nimonic 263 and GTD 111 are being widely used as hot section components, namely, combustion liners, transition pieces and turbine blades, in power generation gas turbines due to their excellent mechanical properties. However, during operations in high temperature and pressure conditions, the components are subjected to vibrations, thereby resulting in wear and erosion. These are the main problems with the hot section components in gas turbines, especially when operating under peak loads. In this study, hardface chromium carbide (CrC) coating reinforced with titanium carbide (TiC) was selected to improve the microstructural and mechanical properties, and particularly to mitigate fretting and erosive wear problems in gas turbine hot sections. Hardface CrC/TiC coatings, in concentrations of 10, 20, 30, 40 and 50 wt. %, were deposited on nickel-based superalloys via air plasma spray and high-veloc ity oxygen fuel (HVOF) spray techniques. These thermal spray techniques were selected for their ability to minimise porosity and to produce rough surfaces with the desired thickness, thus increasing the bonding strength of the hardface coating-substrate system. Microstructural studies using a scanning electron microscope revealed a strong lamellar structure consisting of CrC, TiC and a Ni-binder within the hardface coating. The site inspection results confirmed that wear occurred on the hardface-coated contact surfaces between the combustion liner and transition piece, while erosion occurred on the surface of the turbine blades. The wear and erosion in the form of material loss exceeded the manufacturer's original acceptance limit for the equipment by up to 40%. It was found that the reinforcement with TiC increased the wear resistance of the hardface coating. This was due to the increased hardness, which indicated a lower porosity of 2% compared to the existing hardface coating. The wear and erosion test results proved that the hardface CrC/TiC coating combination with 20%TiC improved the wear and erosion by up to 30%. An analysis of the fretted and eroded surfaces proved that a significant oxide layer was formed at high temperatures of 500, 700 and 900 °C. The wear resistance of the worn samples at these temperatures increased by up to 30% compared to the worn samples at room temperature, 100 °C and 300 °C. The mechanical properties of the hardface CrC/TiC coating combination were also found to have improved by up to 30% for hardness from 615 to 841 HV and 50% for adhesion strength from 47 to 82 MPa, with a reduction of 20% in surface roughness from 5.18 to 4.87 µm. These were attributed to the reduced material loss within the hardface coating, thereby indicating that the hardface CrC/TiC coating had achieved excellent mechanical and thermal stability at high temperatures. The results proved that TiC can be considered as an additional hardface coating to improve the wear protection of CrC. In short, the HVOF-sprayed hardface coating with 20 wt. % TiC was the most preferable coating and had a high potential as it exhibited excellent wear and erosion resistance of up to 30%, with the appropriate hardness, surface roughness microstructure, and thermal stability, thus enhancing the tribological properties of the hardface CrC coating.,Ph.D. | - |
| dc.language.iso | eng | - |
| dc.publisher | UKM, Bangi | - |
| dc.relation | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | - |
| dc.rights | UKM | - |
| dc.subject | Universiti Kebangsaan Malaysia -- Dissertations | - |
| dc.subject | Dissertations, Academic -- Malaysia | - |
| dc.subject | Nickel-based superalloys | - |
| dc.subject | Gas turbines | - |
| dc.subject | Thermal spray techniques | - |
| dc.title | Wear characteristics of thermal sprayed hardface CrC/TiC coated nickel-based superalloys for hot section components in gas turbines | - |
| dc.type | Theses | - |
| dc.format.pages | 209 | - |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_125311+SOURCE1+SOURCE1.0.PDF Restricted Access | 1.17 MB | Adobe PDF |  View/Open |
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