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https://ptsldigital.ukm.my/jspui/handle/123456789/457798| Title: | Structural integrity and thermal nalyses of coated piston crown for compressed natural gas direct injection engine |
| Authors: | Helmisyah Ahmad Jalaludin (P49900) |
| Supervisor: | Shahrir Abdullah, Prof. Ir. Dr. |
| Keywords: | Heat -- Transmission Internal combustion engines Heat-engines Ceramic coating Coatings Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia |
| Issue Date: | 11-Jun-2012 |
| Description: | In a compressed natural gas with a direct injection system (CNGDI) engine, piston crown is continuously exposed to extreme temperature and pressure during combustion. The compression ratio level is typically between that of the gasoline and diesel engines, producing extremely high temperature and pressure which can lead to high thermal stresses. In this study, the yttria partially stabilised zirconia (YPSZ), Y2O3-ZrO2/NiCrAl coating was utilised as the thermal barrier coating (TBC) to compare with the uncoated, tin coated piston crowns in terms of structural integrity and thermal effect. Average values of temperature and pressure of a typical CNGDI engine was selected. A detailed finite element analysis (FEA) was employed to determine locations of hotspot and stress concentration via distribution profiles of both temperature and pressure. In short, it was observed that stresses were mainly concentrated at the area of piston crown where above the pin holes and the sharp edge areas of exhaust valve clearance. The maximum heat flux of the uncoated piston crown was higher than that of the YPSZ/NiCrAl coated and tin coated piston crowns. Heat flux value of the YPSZ/NiCrAl coated piston crown decreased by 98% due to the different properties of coating material. In addition, several samples made of AC8A aluminium alloy were coated with NiCrAl and 7.5Y2O3-ZrO2/NiCrAl by plasma spraying technique. The samples were assessed on their microstructure, surface roughness, hardness and heat resistance using burner rig test. The results showed that the 7.5Y2O3-ZrO2/NiCrAl coating contributed to better performance and could withstand the tests. The heat flux value of the 7.5Y2O3-ZrO2/NiCrAl coated piston crown decreased by 98% compared to uncoated one. By comparing the result from both simulation and experiment, it exhibited that the lower the heat flux gradient, the higher the heat resistance.,Master of Science,Certification of Master's / Doctoral Thesis" is not available" |
| Pages: | 136 |
| Call Number: | TA418.9.C57H438 2012 3 tesis |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_122288+SOURCE1+SOURCE1.0.PDF Restricted Access | 21.67 MB | Adobe PDF |  View/Open |
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