Papers by Keyword: Periodic Heating

Abstract: nternal heating of hollow cylinders with moving periodic heat source is examined in relation to surface treatment applications. This study includes three different cylinder materials, namely aluminum, nickel and titanium. Effective stresses in the cylinder wall are found to be mainly attributed to longitudinal temperature gradients. The aluminum cylinder shows sharper longitudinal temperature gradients as compared to the nickel and the titanium cylinders, which is due to the high value of the aluminum specific heat capacity. However, the larger Eα (elasticity modulus × thermal expansion coefficient) values for nickel cylinder result in higher levels of stress although nickel and titanium cylinders exhibit similar longitudinal temperature profiles. During dwelling time for the heating source at a certain spot, titanium cylinder exhibits lower levels of temperature increase as compared to aluminum and nickel cylinders, due to its lower value of thermal conductivity.

Abstract: The thermal conductivity at the micrometer-scale of AlN ceramics with eliminated grain boundary phase was measured by the thermoreflectance technique with periodic heating. Thermal conductivities were ranged from 160 to 260 W/m•K and an average value of 201 W/m•K was obtained from a 22 m2 area. The variation in the thermal conductivities was related to the individual AlN grains and grain boundary characteristics.