Experimental and theoretical investigation of hollow spherical ceramics

The hollow spherical ceramics used as heat insulation materials have low thermal conductivities. They withstand high temperature and pressure. In this study, the effect of energy gain of hollow spherical ceramics in houses was determined. For this purpose, three closed systems which have 1mx1mx1m dimensions were built. The hollow spherical ceramics were mixed with different paints at a rate of 18 percent by mass and were applied to the inner and outer surfaces of the one of these closed volumes. The plastic paint was applied to the one of the other two closed volumes and the other was insulated with an extruded polystyrene material which has a 3 cm thickness. Thermo-couples were set to the inner and outer surfaces of the closed volumes along with inside and outside the system. Thermostats were used to maintain the temperature of the media inside of them at a constant temperature. While the temperatures inside them were at 28 oC, 30 oC ve 40 oC, consumed electric energy by these closed volumes was determined through the experiments made for these temperatures respectively. On the other hand, measured analog temperature values with thermocouples were transferred to the computer via a hardware equipment in which gathered analog data is formed into digital data. Different tables and diagrams were made from the data obtained through experiments and they were discussed as a result. An experimental study was proposed for the production of hollow spherical ceramics. It was explained that RF (Radio vii Frequency) inductively coupled thermal plasma (ICTP) system may be used in the experimental study for the production of hollow spherical ceramics. Inductively coupled plasma systems are appropriate equipments for the spheroidization processes of powder materials because they have large volumes, high purities, and axial powder injection properties. Especially the long residence times of powders inside the plasma in the reactor are another advantage of ICTPs. The fundamentals of the production of spherical ceramics via inductively coupled thermal plasma systems include melting process of powders in the plasma jet and free falling of them through the reactor. The units of the RF-ICTP system such as powder injection unit, torch, reactor, cyclone, powder filter and gas exit units were described. The plasma gas and the powder material planned to use in the experimental study were explained. System parameters of the RF-ICTP such as gas flow rate, powder flow rate, reactor diameter, power supplied to the plasma system together with RF eletric current generator and the other agents were clarified. Tin powder was produced using gas atomization method in Metrology Laboratory of Mechanical Engineering Department, Engineering and Arhitecture Faculty, Gazi University. This experimental study was made as a groundwork of the planned study by an inductively coupled thermal plasma system. A theoretical study was made on spheroidization of powders via thermal plasma systems. In this study, nonlinear momentum and energy equations were numerically solved through a computer code written in FORTRAN. The effects of plasma gas temperature and velocity, nozzle and particle diameter, initial particle temperature and velocity, and the volume flow rate of plasma gas on particle temperature and velocity were investigated in the analysis. The results obtained via the fifth order Runge-Kutta method were given as diagrams. Key Words : Hollow, Ceramic, ICTP