The Effect of Mg Supplement on Hydroxyapatite Produced by Chemical Precipitation

Hydroxyapatite (HAp) exhibits excellent biocompatibility but the low mechanical strength of normal HAp ceramics generally restricts its use to low load-bearing applications. Magnesium is an attractive material for use in biodegradable implants due to its low density, non-toxicity and mechanical properties similar to those of human tissue such as bone. Its biocompatibility makes it amenable for use in a wide range of applications from bone to cardiovascular implants. The aim of this work was to produce hydroxyapatite powder with chemical precipitation method and supplement Mg and investigate the effect of magnesium on structure of HAp powders. The Mg content ranged between 1 and 2 mol.%. The Mg+HAp powders were examined for morphology. The scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy were used to characterize the specimen powders

THERMO AND PHYSICOCHEMICAL PRINCIPLES: SPECIAL MATERIALS AND AQUEOUS AND ELECTROCHEMICAL PROCESSING

CrN, TiN and Ti-B-N coatings were deposited onto H13 hot-working tool steel and alumina substrates by arc-PVD. The coatings were characterized with respect to their mechanical and structural properties. Oxidation behavior of the coatings on alumina substrates was investigated by TG/DTA. Samples coated on H13 substrates were oxidized in a tube furnace under atmospheric conditions at specific temperatures determined from TG/DTA tests of the same coatings deposited on alumina substrates. The oxide scale morphology was characterized by scanning electron microscopy and X-ray diffraction. Oxide scale thickness change and TG data were used to calculate oxidation reaction activation energies. It was determined that boron addition into TiN coating improves not only mechanical properties but also oxidation resistance. Depending on the substrate material different oxidation activation energy values for the TiN and Ti-B-N coatings were determined revealing the importance of film morphology on oxidation resistance

Advanced Structured Materials

Hydroxyapatite (HA) is one of the most significant calcium phosphate bio-ceramic which is used commercially in biomedical application due to its similar structure with natural bone, bioactivity, and stability in body fluid. HA has excellent biological properties, while plasma sprayed HA coatings have poor bond strength which makes it difficult to use HA coated implants under mechanical stress. Wollastonite (CS) is a calcium silicate based bioactive ceramic which is used in thermal spraying due to its higher bond strength than HA coatings, however it dissolves quicker than HA in simulated body fluid (SBF). The aim of this work is to produce HA-CS composite powder in order to increase bond strength of the coating. In this study, commercial CS and precipitated HA mixture suspension which involved wt. 20% CS was prepared for spray drying (SD) application. HA-CS composite microspheres were granulated by spray drying to supply homogeneity of coating and carry powders to the plasma easily. Afterwards, HA and HA-CS composite microspheres were coated by plasma spraying on carbon steel. Results showed that HA-CS composite coatings have higher adhesion strength, while it decomposes easier to other calcium phosphates than pure HA coating. Additionally, HA-CS coating has higher rate of porosity and un-melted particles

Electrophoretic co-deposition of PEEK-hydroxyapatite composite coatings for biomedical applications

PMID = 2977247