Kinetic studies were conducted on the carbon monoxide reduction of molybdenite in the presence of lime. Contrary to the expectation that the MoS 2 (s) ϩ CaO (s) ϩ CO (g) reaction will result in metal formation, molycarbide was found to form and no Mo was detected in the product. This is explained on the basis of thermochemical considerations, which indicate that the Mo 2 C formation is more feasible by eight orders of magnitude. The effects of quantity of lime in the charge, CO flow rate, temperature (1123 to 1298 K), and time of reduction have been studied. Kinetic analysis reveals that the results on the MoS 2 (s) conversion to Mo 2 C (s) fit into a modified parabolic rate law. Based on the thermochemical calculations and experimental findings, the probable reaction scheme has been identified. Molycarbide appears to form by a three-successive solid-gas reaction path consisting of (1) metal formation by the MoS 2 (s) ϩ CO (g) reaction followed by (2) in-situ carburization of Mo metal by CO (g), and finally (3) the scavenging of the COS (g) by lime, resulting in CaS (s). The latter two reactions drive the overall reaction forward. Further, out of these three consecutive reactions, progress of the overall MoS 2 ϩ CaO ϩ CO reaction seems to be governed by the intrinsic kinetics of the first one. Calcium molybdate, which forms as a transitory phase, plays a significant role by modifying the linear kinetics of the MoS 2 (s) ϩ CO (g) to one of parabolic nature.

In the present investigation a new ternary ceramic matrix composite is developed from Indian fly ash by thermal treatment under reducing atmosphere. The ternary mixture, comprising of Al 2 O 3 -SiC-C, is formed by insitu conversion of SiO 2 to SiC in the fly ash under reducing atmosphere. Analyses of the treated product by XRD, SEM, and EDAX have ensured formation of SiC from SiO 2 . Converted SiC are rod shaped whiskers with the aspect ratio ranging between 40 to 50. The ternary mixture is added to aluminum melt in a bottom pouring pit type resistance furnace for the preparation of novel aluminum fly ash metal matrix composite (ALFMMC). Physical and mechanical properties of the novel ALFMMC (treated fly ash) composite are evaluated. For comparison purpose, aluminum fly ash composite is prepared with (untreated flyash) under identical condition of melting and casting. Wear resistance is found to be superior for the novel composite.

Effects of thermal cycling in a reducing (deuterium) atmosphere on the structure and chemistry of Cr/Cu/Cr/polyimide (PI)/Si and Au/Cu/Ti/polyimide (PI)/Si multilayer systems have been studied. In the Cr/PI system the interface between the Cr and PI was sharp and distinct in the as-deposited state, and after the anneal in the reducing atmosphere. Tensile cracks through the Cr/Cu/Cr layers were found after annealing and are the result of thermal stresses. No evidence for significant diffusion of Cr into the PI was found. In the Ti/PI system, the interface between the Ti and PI was sharp in the as-deposited state. After annealing in vacuum and in the reducing environment, regions of the interface between the Ti layer and the PI were converted to an oxide, Ti5O9. Annealing in the deuterium environment also caused delamination of the Ti film from the PI and blistering of the metal in the sample interior. No significant diffusion of the Ti into the PI was detected. In both systems, the metal in contact with the PI acted as a barrier to the diffusion of Cu into the PI.