Composition and structure of calcium-phosphate coatings on Ti3AlC2 produced by sol-gel synthesis

Abstract

Calcium phosphate materials have been widely used in medical practice for decades. Due to their bioactivity and integration with human hard tissues. They have been produced in the form of dense and porous ceramics, powders and needle-like crystals (whiskers). Despite the high mechanical properties (hardness, compressive strength), calcium phosphate ceramics are mainly used in medicine mainly as the fillers for bone defects formed due to injuries or diseases because they have high fragility and low crack resistance. These circumstances do not allow using them in the sites that have high mechanical loads (e.g. hip surgery). To solve these problems metal implants are used. Among them, Ti-based alloys are the most widely used due to its high mechanical properties, biocompatibility and high corrosion resistance. Recently, the data on the use of MAX phases as medical materials to create the composites based on Ti3SiC2 have appeared in the literature. Calcium phosphate coatings were obtained on Ti3AlC2 substrate by the sol-gel method. The effect of temperature, holding time, chemical compositions of reactants on the phase composition and structure of the samples are discussed. XRD measurements have revealed that the initial coatings consists of nanoparticles sized 10-50 nm. Light and scanning electron microscopy (SEM) were applied to study the morphology of the coatings. It have been shown that the coatings had thickness in an interval 40-100 mm and had the homogenous structure. It has been established by X-ray phase identification that the coating after heating at 1000oC during 1 hour contained b-tricalcium phosphate (b-TCP). It was found, that the thickness and phase composition of coatings depend on the time of coating in calcium phosphate solution. The optimal conditions for the formation of coatings are established.