optimize the design of domestic hip prostheses are reviewed. These efforts are focused on new biomaterials, such as tetragonal zirconia bioceramics made of highly pure nanocrystalline powders, nanostructured bioactive ceramic coatings, and new titanium alloys without toxic elements, and new processes such as improved machining of ceramic heads using special diamond nanopowders and advanced software for optimizing the design of hip prostheses and process control.

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A bioinert ceramic based on partially stabilized tetragonal zirconium dioxide has been developed and its chemical and phase composition, microstructure, and physical -technical properties have been investigated. Ceramic heads for endoprostheses for the coxofemoral joint -28 mm in diameter with less than 0.02 mm roughness R a of the spherical surface and 1 mm deviation from sphericity -have been fabricated. It is shown that the bioceramic which has been developed and the ceramic heads for endoprostheses fabricated from it meet the technical characteristics and parameters required by international standards and their quality is at least as good as that of the analogous articles manufactured by well-known firms.

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621.793Operation of coatings based on tialite, γ-TiAl, titanium aluminides with discrete inclusions of TiN and also alloys based on cobalt, nickel, and titanium in friction pairs with polyethylene grade "Chirulen" and stainless steel 12Kh18N10T is studied. It is established that tialite coatings formed from nanostructure powders of Ti − Al by detonation deposition are the best for operation under dry friction conditions in a pair with stainless steel 12Kh18N10T (minimum friction coefficient and minimum wear of the contact surfaces). It is shown that in the sliding rate range selected effective operation of material in friction pairs with polymer is provided due to transfer it to the contact surface and formation between rubbing surfaces of a thin film fulfilling the function of a solid lubricant. It is established that stable operation with the minimum wear in a friction pair with polyethylene grade "Chirulen" is provided by a coating of γ-TiAl and Al 2 TiO 5 , and also coatings based on titanium aluminide with fine TiN inclusions.

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The methods of potentiodynamic polarization curves and quantitative Auger electron spectroscopy are used to determine the mechanism whereby a dense protective nanofilm (up to 20 nm thick) forms. The film consists of Ti 2 O, TiO, and Ti 2 O 3 lower titanium oxides and forms under the layer of TiO 2 (10 nm) and oxygen chemisorbed over an orthopedic prosthesis (90.2 at.% Ti-9.8 at.% Si alloy) during electrolysis in a 3% NaCl solution, as the main component of the tissue fluid (Hank's physiological solution).A great many people all over the world suffer from arthrosis, osteoporosis, cervical hip fracture, and other diseases of bones. Orthopedic prostheses help to prevent immobility and recover the function of the limbs, such as internal prostheses and hip joint, knee joint, and other substitutes. The first orthopedic prostheses were made primarily of titanium alloys; titanium was not combined with other metals to avoid an undesirable galvanic couple. Titanium turned to be the most suitable metal whose mechanical properties were closest to the bone tissue. In particular, its fatigue takes twice as long to occur as compared with steel. Moreover, titanium and some of its alloys have ideal biocompatibility: titanium does not react with body tissues while being organically overgrown with bone tissue [1,2].Later on, Ti-Ni, including titanium nickelide [3], and VT6, Ti-Si, and other alloys came into use along with titanium in musculoskeletal operations, but the mechanical properties of these alloys have been examined much greater than chemical ones. Of special interest is the interaction of alloys for hip joint prostheses with tissue fluid. The interaction of samples with Hank's solution, which mainly consists of a 3% NaCl solution, is commonly modeled in such studies.This paper studies the corrosion resistance of a new Ti-Si alloy, such as Ti-6% Si, which does not contain toxic elements (V and Al). Preliminary mechanical tests have shown that Ti-Si alloy meets most requirements for prosthesis materials. For example, their strength reaches 700 to 1100 MPa and plasticity is 9 to 20% depending on the composition and thermomechanical treatment [4].Titanium of grade VT1-0 (as per GOST 19807-91) and silicon of grade KR1 were the starting materials. The test samples were cut out from cast billets produced by the arc plasma process described in [4]. According to

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