The oxidation kinetics of several single-crystal and polycrystalline silicon carbide materials and single-crystal silicon in dry oxygen over the temperature range 1200" to 1500°C were fitted to the linear-parabolic model of Deal and Grove. The lower oxidation rates of silicon carbide compared to silicon can be rationalized by additional consumption of oxidant in oxidizing carbon to carbon dioxide. The (0001) Si face of the silicon carbide platelets exhibited lower parabolic oxidation rates than the (000%) C face, by a factor of 10 at 1200°C. Apparent activation energies increased from a value of 2120 kJ/mol below 1400°C to a value of =300 kJ/mol above this temperature. The (0001) Si face exhibited this high activation energy over the entire temperature range. The controlled nucleation thermally deposited material exhibited the highest oxidation rates of the polycrystalline materials followed by the hot-pressed and sintered a-silicon carbides. In general, the oxidation rates of the polycrystalline materials were bracketed by the oxidation rates of the basal planes of the single-crystal materials. Higher impurity concentrations and higher density of nucleation sites led to a greater susceptibility to crystallization of the scale which significantly complicated the oxidation behaviors observed. When crystallization of the oxide scale occurred in the form of a layer of spherulitic cristobalite crystals, a retardation of the oxidation rates was observed. An accelerated oxidation behavior was found when this coherent layer was superseded by the formation of fine mullite crystals.

The indicative conclusions from this study suggest that terminal care for some elderly patients remains hampered by a reluctance of nurses and doctors to be more open in their communication about death. It would appear that hospital culture and the mores, beliefs and ideologies that emanate from the biomedical model, significantly shape the experiences of older dying patients.

There is a need to improve communication with patients and families about diagnosis and prognosis to ensure that effective communication takes place and 'blocking behaviour' is avoided. The findings also challenge practitioners to focus attention on death as a process, and to prioritize patients' needs above those of the organization. Moreover, there is the need for guidelines to be developed enabling patients to have a role in shaping events at the end of their lives.

The oxidation kinetics of sintered α‐ and hot‐pressed SiC were investigated over the temperature range 1200° to 1500°C. Oxide thicknesses were measured by ellipsometry, interferometry, and profilometry. The two materials behaved similarly, exhibiting parabolic behavior for short times (up to 100 min) followed by decreasing rates for longer times. The oxidation rates for the sintered material were lower than for the hot‐pressed material at all temperatures studied. Apparent activation energies varied with temperature, from 134 to 389 kJ/mol for the sintered alpha material and from 155 to 498 kJ/mol for the hot‐pressed variety. Platinum‐marker experiments indicated that new oxide is formed at the silicon carbide/ oxide interface. It is proposed that the diffusion of oxidant through the growing oxide film is the rate‐controlling process. The details of the oxidation kinetics were complicated by the partial crystallization of the oxide film at higher temperatures, leading to complex paths for transport of oxidant through the film so that the apparent activation energies are difficult to interpret.