Modification of the surface of titanium alloys by the synthesis of coatings by the PEO method in alkaline electrolytes saturated with diatomite

One of the most promising directions of modern materials science is the search for methods of improving the biocompatibility properties of metals used in implantology, which will allow to reduce the percentage of rejection of implants by the living organism. Therefore, it is promising to use processing methods to change the state of the surface of metals due to surface modification, which includes the method of plasma electrolytic oxidation. The main goal of this work was to develop a technological process for obtaining coatings with higher biocompatibility compared to the base metal due to the introduction of natural components into the coating. The presence of elements in biocoatings and their quantity was determined using a scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), which allowed for targeted analysis of the surface of the samples. The elemental composition of coatings synthesised on the basis of titanium alloy in alkaline electrolytes based on KOH, liquid glass of calcium hydroxide, sodium polyphosphate and sodium pyrophosphate with the addition of hydroxyapatite and diatomite was researched in the work. A direct relationship between the composition of the electrolyte and the Ca/P ratio was established. It has been proven that biocoatings synthesised in alkaline solutions by the PEO method satisfy the conditions of biocompatibility. It has been established that in an environment containing alkalis and phosphates, coatings are synthesised for which Ca/P = 1.21. The introduction of hydroxyapatite into the electrolyte leads to an increase in the Ca/P ratio to a value of 1.28, and an increase in the concentration of the electrolyte and the addition of diatomite increases this ratio to a value of 1.57. The obtained results establish the possibility of a wide range of regulation of the Ca/P ratio in the biocoating