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Abstract: A desymmetrizing dehydrogenation process catalyzed by a chiral primary amine is described herein. The reaction proceeds through the oxidation of a ketone enamine by IBX and enables the highly enantioselective desymmetrization of 4‐substituted cyclohexanones with the generation of chiral 4‐substituted cyclohexenones containing a remote γ‐stereocenter. [ABSTRACT FROM AUTHOR]

Ti 0.51 C 0.24 N 0.25 and Ti 0.51 C 0.26 N 0.21 O 0.02 coatings were deposited by medium temperature chemical vapor deposition, their oxidation resistance and thermal stability at 600 °C were compared. Ti(C,N,O) coating is oxidized faster than Ti(C,N) coating. The oxidation resistance of Ti(C,N,O) coating is impaired not only by the existence of more pores, fissures and cracks in the oxide layer, but also by lower interfacial adhesion. Higher tensile stress has a negative impact on the oxidation resistance of Ti(C,N,O) coating. It promotes the formation and development of more defects and cracks during cyclic oxidation, it is also harmful to the interfacial adhesion. Although the oxidation resistance of Ti(C,N,O) coating is inferior, the thermal stability is improved. The incorporation of oxygen slows down the phase transformation of Ti(C,N,O) at 600 °C. During the annealing, the hardness of Ti(C,N,O) coating is always higher than that of Ti(C,N). [ABSTRACT FROM AUTHOR]

Abstract: Good oxidation resistance of hard coatings is important for cutting tools. Ti0.5Al0.5N coating and Ti0.5Al0.4Si0.1N coating were deposited by cathodic arc evaporation and their oxidation behavior at 850 °C, 900 °C and 1000 °C was compared. The effect of Si addition on the oxidation resistance of Ti0.5Al0.4Si0.1N was investigated. Results show that the oxidation resistance of Ti0.5Al0.4Si0.1N coating at 850–1000 °C is superior to Ti0.5Al0.5N coating. The improved oxidation resistance of Ti0.5Al0.4Si0.1N coating can be ascribed to the combined action of Al2O3 and SiO2 barrier layer, the reduction of columnar structure and the refinement of grains. In particular, Si addition increases the diffusion coefficient of Al and promotes the preferential formation of Al2O3 barrier layer. [Copyright &y& Elsevier]