Spheroidized nano [alpha]-tricalcium phosphate powders using Suspension Induction Plasma Synthesis (SIPS) for bone cement applications

• Main Author: Park, Hyunjin
• Other Authors: Gitzhofer, François
• Language: English
• Published: Université de Sherbrooke 2007
• Online Access: http://savoirs.usherbrooke.ca/handle/11143/1405

In this thesis, Suspension Induction Plasma Synthesis (SIPS) has been studied to produce spherical and nano alpha-tricalcium phosphate ([alpha]-TCP) powders for bone cement applications. Previously, [alpha]-TCP powders were only produced by high-temperature solid/solid reaction in conventional oven. SIPS synthesis is based on the allotropy of tricalcium phosphate (TCP): a suspension of the low-temperature phase, [bêta]-TCP, is atomized in an induction plasma to synthesize the alpha high-temperature phase, [alpha]-TCP. Therefore, the purpose of this study is to understand the effects of suspension and plasma conditions on the plasma-synthesized powder (composition and morphology). To achieve this aim, an experimental plan was realized to study the influence of several parameters. Suspension concentration, feed rate and composition were selected for the suspension conditions. Plate power, chamber pressure and probe position were selected for the plasma conditions. Generally, filter powder has higher percentage of spheroidized [alpha]-TCP than reactor powder and all SIPS parameters have effect on the final product. It was found that low suspension concentration (40 wt% of [bêta]-TCP), feed rate (5 ml/min), suspension composition (H[subscript 2]O), low plate power (24 kW), low chamber pressure (150 Torr) and low probe position (20 mm lower) produced a high percentage of spheroidized [alpha]-TCP. Specially, in the plasma condition, there is a correlation between high plate power, high chamber pressure and probe position. Indeed, high plate power and high chamber pressure produced high percentage of [alpha]-TCP, when the probe position was 20 mm lower. This thesis is the first investigation to study SIPS as a way to produce spherical and nano-scale [alpha]-tricalcium phosphate powders. These features will benefit the bone cements concerning their injectability and their mechanical properties.