Sharif Digital Repository

The behavior of three types of non-coking coals from Iranian's deposits in thermal regime of tunnel kiln direct reduction of the iron (TKDRI) process has been investigated. The heating condition of raw materials in tunnel kiln was simulated in a vertical TGA for three different non-coking coals. For non-isothermal devolatilization of coals from room temperature to 1100 °C, the heating rates of 1.5, 3 and 7 °C/min were chosen. Coal mass and volumetric changes during devolatilization were observed by TGA and dilatometry analysis. XRD and scanning electron microscopy of raw coals and chars were used to analyze coal structural changes. In non-isothermal low heating rate pyrolysis of coal, most... 

This work presents the effect of co-sintering on the densification and microstructural evolution in the two-layer stepwise graded composite of INCONEL 718 and INCONEL 625 superalloys. A pressureless co-sintering method in conjunction with a powder layering technique was used. The sintering was carried out in solid state and liquid phase in temperature ranging from 1260 °C through 1300 °C for 60 minutes in a low pressure of an argon atmosphere. Nonisothermal sintering behavior was also examined by dilatometric analysis. Similarly, the sintering response of the individual layers was characterized. The results reveal an enhanced densification rate during co-sintering of the composite layers....