The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO 2 and Ca 5 (PO 4 ) 3 OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 lm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO 2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The microRaman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.

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The study aimed at optimizing the suspension plasma spraying of TiO 2 coatings obtained using different suspensions of fine rutile particles in water solution onto aluminum substrates. The experiments of spraying were designed using a 2 3 full factorial plan. The plan enabled to find the effects of three principal parameters, i.e. electric power input to plasma, spray distance, and suspension feed rate onto microstructure of coatings, content of anatase phase and size of anatase crystals in the coatings. The microstructure of deposits was observed with scanning electron microscope (SEM) and optical microscope and their composition was characterized using energy dispersive spectrometry (EDS). The observations were made on the coatings surface and their cross-sections. The latter made it possible to determine the coatings thicknesses to be in the range from 8 to 33 lm.