The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems ...The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.展开更多
Buildings constructed using modern materials such as cement are energy-intensive, facilitate heat transfer and thus promote warming inside the building. However, the Sudano-Sahelian regions have a hot climate occupyin...Buildings constructed using modern materials such as cement are energy-intensive, facilitate heat transfer and thus promote warming inside the building. However, the Sudano-Sahelian regions have a hot climate occupying a large period of the year, thus requiring not only sustainable construction materials, but also which provide thermal comfort in the building by limiting the energy demand for air conditioning. These qualifications are important for sub-Saharan African countries in general and those of the Sudano-Sahelian zone in particular, which need ecological materials with good thermal performance to limit heating inside buildings. This study is an energy recovery of agricultural waste in buildings with a view to offering the populations of the northern regions of Cameroon suitable materials at lower cost for the construction of buildings. The soil used for this study was extracted from the locality of Yagoua where the populations make abundant use of mud bricks. Fonio waste was incorporated at low levels into the earth bricks, particularly at 0%, 1%, 2%, 3%, and 4%, with a view to strengthening their thermophysical and mechanical properties. The results obtained indicate that earth bricks reinforced with 4% waste showed better thermal and mechanical insulation properties compared to other formulations with an improvement of 16% and 78% respectively compared to the unreinforced samples. This research allows us to conclude that fonio waste can be used practically without expense in the building with a view to its energy recovery and will promote not only thermal comfort and the limitation of the energy supply for air conditioning, but the construction of more sustainable buildings with a cleaner environment.展开更多
基金Project(2011-0030058) supported by the National Research Foundation of Korea(NRF) Funded by the Korean Government(MSIP)Project(20134030200220) supported by the Human Resources Development Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Funded by the Korea Government Ministry of Trade,Industry and Energy and by the Korea Institute of Materials Science(KIMS) in 2013
文摘The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.
文摘Buildings constructed using modern materials such as cement are energy-intensive, facilitate heat transfer and thus promote warming inside the building. However, the Sudano-Sahelian regions have a hot climate occupying a large period of the year, thus requiring not only sustainable construction materials, but also which provide thermal comfort in the building by limiting the energy demand for air conditioning. These qualifications are important for sub-Saharan African countries in general and those of the Sudano-Sahelian zone in particular, which need ecological materials with good thermal performance to limit heating inside buildings. This study is an energy recovery of agricultural waste in buildings with a view to offering the populations of the northern regions of Cameroon suitable materials at lower cost for the construction of buildings. The soil used for this study was extracted from the locality of Yagoua where the populations make abundant use of mud bricks. Fonio waste was incorporated at low levels into the earth bricks, particularly at 0%, 1%, 2%, 3%, and 4%, with a view to strengthening their thermophysical and mechanical properties. The results obtained indicate that earth bricks reinforced with 4% waste showed better thermal and mechanical insulation properties compared to other formulations with an improvement of 16% and 78% respectively compared to the unreinforced samples. This research allows us to conclude that fonio waste can be used practically without expense in the building with a view to its energy recovery and will promote not only thermal comfort and the limitation of the energy supply for air conditioning, but the construction of more sustainable buildings with a cleaner environment.
