Samuel F. Hulbert

Compatibility of Bioceramics with the Physiological Environment

When prosthetic materials are placed in the body, consideration must be given to (1) the effect of the physiological environment upon the prosthetic metal, medical polymer, or bioceramic, and (2) the effect of the prosthetic material and its corrosion or degradation products upon the fluids and tissues of the surrounding environment. The interaction which occurs between biomedical materials and the physiological environment is discussed with emphasis on the mechanism of biocorrosion, biodegradation, and wear as well as on the toxicology of implant materials. Since bone and soft tissue invade certain physiologically acceptable porous ceramic materials, there is reason for optimism that ceramics will become very useful materials of construction for orthopedic and oral appliances.

Effect of processing parameters on the kinetics of decomposition of magnesium sulphate

Abstract Thermogravimetric analysis was used to study the kinetics of decomposition of MgSO 4 between 920°C and 1080°C as a function of sample mass and processing pressure. The kinetics of decomposition of MgSO 4 can be represented either by the contracting sphere (phase boundary controlled) rate equation or by a nuclei growth equation with ( m ) equal to 1.10. The contracting sphere model gives a slightly better mathematical representation. The experimental activation energy of 74.5 ± 3 kcal/mole is close to the heat of decomposition. The measured kinetics are influenced by the reversible nature of the reaction. Pelletization, or increasing the sample mass, retards the reaction by increasing the partial pressure of SO 3 developed within the powder compact.

Characterization of Tissue Growth into Pellets and Partial Sections of Porous Porcelain and Titania Implanted in Bone

Porous titania and porous porcelain were selected for this investigation* because of their chemical inertness and ease of fabrication. Titanium metal implants have demonstrated a high degree of tissue tolerance1,2; these are certain to have maintained some oxide layer on the surface. Also, porcelain was shown to be non-toxic when implanted intramuscularly in rabbits3.

Kinetics of Dissolution of Magnesium Oxide in a Sodium Silicate Melt

A continuous measurement process is needed for studying the kinetics of refractory corrosion. Dissolution kinetics of magnesium oxide in a sodium silicate melt in the temperature range of 1100°C to 1220°C were studied. The rate of reaction was observed by using a continuous measurement process which was designed especially for this investigation but can be used for other refractory corrosion reactions. With this process, the weight loss can be measured at any time during the experiment, thus providing many advantages over previous techniques in which only the starting and ending points can be measured.