Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 °C. SEM and TEM investigations...Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 °C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 μm. In spite of sub-micron grain size, composites showed relatively high thermal conductivity （TC）, 55-107 W/（m·K）. The thermal expansion coefficient （CTE） of the composite produced with commercial Al source, which has the highest TC of 107 W/（m·K）, was 6.5×10-6 K-1. Despite the high CTE of Al （23.6×10-6 K-1）, composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process.展开更多
Tapioca is economical crop grown in Thailand and continues to be one of the major sources of starch.Nowadays,tapioca starch has been widely used in industrial applications,however the native form of starch has limited...Tapioca is economical crop grown in Thailand and continues to be one of the major sources of starch.Nowadays,tapioca starch has been widely used in industrial applications,however the native form of starch has limited the applications.Thus scientists try to modify the properties of starch for increasing the stability of the granules,pastes to low pH,heat,and shear during the food process.We modify the tapioca starch by plasma treatment under an argon atmosphere.The degree of modification is determined by following water content in the starch granules.The tablet samples of native starch are also prepared and compared with the plasma treated starch.Before plasma treatment,the starch tablets are stored under three different relative humilities(RH)including 11%,68%,and 78%RH,respectively.The samples are characterized using FTIR spectroscopy associated with the degree of cross-linking.The results show that the water molecules are engulfed into the starch structure in two ways,a tight bond and a weak absorption of water molecules which is represented at two wave number of 1630 cm^(-1) and 3272 cm^(-1),respectively.The degree of cross-linking can be identified from the relative intensity of these two peaks with the C–O–H peak at 993 cm^(-1).The results show that the degree of cross-linking increase in the plasma treated starch.The degree of cross-linking of the treated starch with high relative humidity is less than that of the treated starch with low relative humidity.展开更多
基金The Foundation for Scientific Research Projects of Mugla Sitki Kocman University(Project No.10/30)The Scientific&Technological Research Council of Turkey(TUBITAK,Project No:108M194)for funding the present work
文摘Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 °C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 μm. In spite of sub-micron grain size, composites showed relatively high thermal conductivity （TC）, 55-107 W/（m·K）. The thermal expansion coefficient （CTE） of the composite produced with commercial Al source, which has the highest TC of 107 W/（m·K）, was 6.5×10-6 K-1. Despite the high CTE of Al （23.6×10-6 K-1）, composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process.
基金Supported by the Commission for Higher Education,Ministry of Education of Thailand and Faculty of Science,Mahidol University。
文摘Tapioca is economical crop grown in Thailand and continues to be one of the major sources of starch.Nowadays,tapioca starch has been widely used in industrial applications,however the native form of starch has limited the applications.Thus scientists try to modify the properties of starch for increasing the stability of the granules,pastes to low pH,heat,and shear during the food process.We modify the tapioca starch by plasma treatment under an argon atmosphere.The degree of modification is determined by following water content in the starch granules.The tablet samples of native starch are also prepared and compared with the plasma treated starch.Before plasma treatment,the starch tablets are stored under three different relative humilities(RH)including 11%,68%,and 78%RH,respectively.The samples are characterized using FTIR spectroscopy associated with the degree of cross-linking.The results show that the water molecules are engulfed into the starch structure in two ways,a tight bond and a weak absorption of water molecules which is represented at two wave number of 1630 cm^(-1) and 3272 cm^(-1),respectively.The degree of cross-linking can be identified from the relative intensity of these two peaks with the C–O–H peak at 993 cm^(-1).The results show that the degree of cross-linking increase in the plasma treated starch.The degree of cross-linking of the treated starch with high relative humidity is less than that of the treated starch with low relative humidity.
