Mechanical properties titanium-containing systems

Iron-chromium alloys, free from carbon, may be prepared from chromite by the alumino-thermic method. From a study of the cooling-and freezing-point curves it has been suggested that a compound, Cr Fe, exists, but this is questioned by Janecke, who studied the iron-chromium system by means of fusion curves and by the microscopic study of polished sections of various alloys between the limits 10 Fe 90 Cr and 90 Fe 10 Cr, and came to the conclusion that the system consists of a single eutectic which can form mixed crystals with either component. The eutectic contains 75 per cent, of chromium and melts at 1320° C. The addition of chromium to iron increases the readiness of attack by hydrochloric and sulphuric acids, but towards concentrated nitric acid the alloys are rendered passive. They remain bright in air and in water. The presence of carbon increases the resistance to acids and renders them very hard if carbon-free, they are softer than cast iron. All the alloys up to 80 per cent, chromium are magnetic. Molybdenum, titanium, vanadium, and tungsten improve the mechanical properties and increase the resistance to acids. 

Polybutylene therephthalate (PBT) has been used as a blend component to provide chemical resistance in various systems, but the most interesting one results from a combination with polycarbonate and, eventually, an Impact modifier of the coreshell type. Polyester blends containing polycarbonate exhibit ester interchange chemical reactions, which add to the complexity of property control of these materials. DEVAUX and co-workers (14) have examined the transesterification reaction catalysed by residual catalysts in PBT which can lead to the formation of block and random copolymers. They have shown that allyl or aryl phosphites inactivate the residual titanium catalyst and minimise the transesterification reaction. HOBBS et al. (15) reported a way of controlling miscibility behaviour, morphology and deformation mechanisms, in order to obtain blends compati-bilisation and excellent mechanical properties. 

Lehtola, V.-M. Heinamaki, J.T. Nikupaavo, P. Yliruusi, J.K. The mechanical and adhesion properties of aqueous-based hydroxypropyl methylcellulose coating systems containing polydextrose and titanium dioxide. Drug Dev. Ind. Pharm. 1995, 21 (6), 675-685. 

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