Thermal characterization of commercially pure titanium for dental applications

Abstract

Thermal characterization of commercially pure titanium was carried out in dry air to investigate the oxidation kinetics, the oxide structures and their properties. Oxidation kinetics were performed by thermogravimetry in isothermal conditions between 300 and 750 °C for 48 hours and the oxide structures were studied by differential thermal analyses and X ray diffraction between room temperature and 1000 °C. The oxidation kinetic increases with temperature and is very fast in the initial period of oxidation, decreasing rapidly with time, especially up to 600 °C. Kinetic laws varied between the inverse logarithmic for the lower temperatures (300 and 400 °C) and the parabolic for the higher temperatures (650, 700 and 750 °C). Evidences from X ray diffraction and differential thermal analyses showed that crystallization of the passive oxide film, formed at room temperature, into anatase occurs at about 276 °C. The crystallized oxide structure is composed of anatase between 276 and 457 °C, anatase and rutile sublayers between 457 and 718 °C, and a pure layer of rutile after 718 °C. Rockwell-C adhesion tests reveled that the oxide films formed up to 600 °C have a good adhesion. Vickers indentations on the oxidized surfaces showed that the hardness of the oxide film, measured at 600 and 650 °C, is approximately 9500 MPa. At these temperatures the surface roughness varied between 0.90 and 1.30 mm

Microstructure development on sintered Ti/HA biocomposites produced by powder metallurgy

“…However, it is worth recalling that Ti particles of the starting material are covered with a passive oxide film of anatase. During the heating, the anatase is converted into crystalline rutile (> 730 °C) 21 . Furthermore, since oxygen is trapped inside the pores of the green compact during mechanical densification, more rutile can be form during the heating.…”

“…The peak at about 50 °C is due to volatilization of alcohol molecules adsorbed on the surface of the passive film. At approximately 460 °C rutile begins to nucleate and then the oxide film is constituted of anatase and rutile sublayers 21 . The peak at 725-730 °C indicates that anatase is no longer stable, converting to rutile, which is the only stable oxide above 730 °C 21 .…”

“…At approximately 460 °C rutile begins to nucleate and then the oxide film is constituted of anatase and rutile sublayers 21 . The peak at 725-730 °C indicates that anatase is no longer stable, converting to rutile, which is the only stable oxide above 730 °C 21 . The exothermic reaction at approximately 1023-1026 °C is related to the decomposition of HA.…”

The Cyclic Oxidation and Hardness Characteristics of Thermally Exposed Titanium Prepared by Inductive Sintering-Assisted Powder Metallurgy

“…From Figure 1a, it is evident that the mass gain versus oxidation time curves generally fit to the parabolic function at temperature range of 700-900 • C. The curves of the square of mass gain of the samples during oxidation, which are close to a linear line at all oxidation temperatures, are shown in Figure 1b. It can be noted that the oxidation kinetics obey a parabolic law at all oxidation temperatures [16][17][18]. Kofstad et al [19] also determined that the oxidation behavior of Ti was dependent on temperature and time, and that its oxidation behavior followed a parabolic law in the temperature range of 600 • C to 1000 • C. As the mass gain versus oxidation time curves obey the parabolic law, the parabolic rate constant (k p ) of Ti can be measured as follows [20]:…”

Preparação e caracterização de um biocompósito obtido pela mistura de hidreto de titânio com nitrato de cálcio para implantes dentários

“…Tendo em vista a presença de oxigênio, o pico a 330 o C corresponde a formação de oxihidreto de titânio e/ou à cristalização do anatásio [13]. O pico a 420 o C está próximo daquele de formação do rutilo [13]. O pico endotérmico a aproximadamente 50 o C na curva de DSC é devido à evaporação da água adsorvida na superfície do pó de hidreto de titânio.…”