Materials science

 

RESEARCH OF THE STRUCTURE AND PROPERTIES OF POROUS TITANIUM COATINGS OBTAINED BY VARIOUS METHODS

 

A.E. Ivanov, S.V. Skvortsova, N.V. Ruchina, N.A. Mamontova, V.S. Spektor, M.D. Tevs

 

The paper describes a study of porous titanium coatings obtained by 3D printing, ion-plasma spraying and a GRIPTION® coating. A comparison was made of the effect of various methods of obtaining porous titanium coatings on the porosity and structure of the coatings. Increase of adhesion strength of porous titanium coating after application of thermal hydrogen treatment.

 

Keywords: titanium alloys, titanium coating, porous coating, osseointegration.

 

INVESTIGATION OF CORROSION RESISTANCE OF MEDICAL MATERIALS FOR IMPLANTS IN RINGER'S SOLUTION CONTAINING IODINE IONS

 

Yu.V. Chernyshova, E.O. Agarkova, A.V. Neiman, А.А. Lidzhiev, A.V. Zairov

 

The corrosion resistance of the main materials for implantation in Ringer's solution with the addition of povidone-iodine was studied.

It has been established that samples of commercially pure titanium, VT6 and VT20 titanium alloys, and TN1 alloy based on titanium nickelide have the highest corrosion resistance. It has been shown that the addition of povidone-iodine to Ringer's solution leads to a decrease in the corrosion characteristics of the cobalt-chromium alloy and an almost complete loss of the corrosion resistance of 12Kh18N10T austenitic stainless steel.

The effect of vacuum ion-plasma nitriding (VIPA) on the electrochemical characteristics of samples of commercially pure titanium, VT6 and VT20 titanium alloys in a solution containing povidone-iodine has been studied. It has been established that the use of HIPA leads to a significant increase in stationary potentials and a decrease in the current density in the passive region, i.e. has a positive effect on the corrosion resistance of the studied materials in a solution with the addition of povidone-iodine.

 

Keywords: povidone-iodine, titanium alloys, medical materials.

 

COMPARISON OF THE MECHANICAL PROPERTIES OF BARS FROM ALLOY VT6 WITH GLOBULAR AND LAMELLAR STRUCTURE

 

Yu.B. Egorova, S.V. Skvortsova, L.V. Davidenko, A.V. Shmyrova, O.N. Gvozdeva

 

Experimental data on the combined effect of the chemical composition, type and parameters of the structure on the mechanical properties of rolled bars of VT6 alloy are presented. It has been substantiated that at the same strength level, the relative elongation of the bars with a globular structure is, on average, 5% higher in comparison with the lamellar structure, and the transverse narrowing is 15% higher. For bars of VT6 alloy with globular and lamellar structures, the values of equivalents for aluminum and molybdenum and structure parameters have been established, which ensure compliance with the requirements of industry standards.

 

Keywords: titanium alloy VT6, rolled bars, chemical composition, structure, mechanical properties, statistical studies.

 

ESTIMATION OF ENDURANCE LIMIT OF TITANIUM ALLOYS

 

S.V. Serikov

 

Comparison of titanium alloys in terms of high-cycle fatigue resistance has a number of objective difficulties. The paper proposes, as a discussion, to replace the method for determining the endurance limit with a method for assessing operational reliability, characterized by two parameters: the coefficient of dynamic viscosity and the specific work of destruction. The new approach is illustrated with specific experimental data for titanium alloys (Ti-1100, Ti-6Al-4V, VT20). The formulated method is simpler in form and physically substantiated in content.

 

Keywords: titanium alloy, endurance limit, dynamic toughness coefficient, specific fracture energy, high-cycle fatigue.

 

 

Processing technologies

 

SURFACE MICROALLOYING OF TITANIUM ALLOYS IN THE MANUFACTURE OF FORCE ELASTIC ELEMENTS OF SPACECRAFT

 

V.K. Shatalov, A.O. Shtokal, E.V. Rykov, A.V. Artemiev, O.P. Bazhenova, D.V. Sergeev

 

Surface saturation of titanium alloys with oxygen is carried out by forming stable oxide coatings on the surface of hard-facing bars. In the course of many years of research work at MSTU. N.E. Bauman (Kaluga), it was found that the most technologically advanced way to create an oxide layer for a hard-facing bar is microarc oxidation (MAO). The proposed method for oxygen microalloying of the surface of titanium alloys using hard-facing bars treated by microarc oxidation is applicable in the manufacture of extended force elastic elements of spacecraft and has a number of advantages:

1. Allows to increase the hardness and wear resistance of the mating surfaces of the structure.

2. Able to provide the required characteristics of the material of the part in a wide range, allows to form a composite material with a predetermined set of performance properties.

3. Allows to strengthen titanium alloys and structures from them, which are not strengthened or insufficiently strengthened by heat treatment.

4. Does not require complex and expensive technological equipment, and in some cases does not require subsequent machining.

5. Allows to reduce the mass of the landing module of the spacecraft.

The disadvantages of the proposed method include the high qualification of the working personnel, as well as the significant laboriousness of the process, which makes the use of oxygen microalloying economically justified only in a single and small-scale type of production.

 

Keywords: titanium, microalloying, hard-facing bars, microarc oxidation, spacecraft, landing pad.

 

 

Application. Quality. Market.

 

THERMOCYCLIC STRENGTH OF TITANIUM ALLOY IN THE DETAILS OF POWER EQUIPMENT

 

V.V. Travin, A.I. Zmozhniy, G.A. Shevelev, Yu.A. Denisenko
 

Some questions of experimental and numerical investigation thermo-cyclic strength for power equipment units, made of pseudo-alpha titanium alloy 5B-type, are examined in this article. Results of testing and FEM-analysis strain-stress state in concentration zones are presented, as well as results of brittle failure parameters calculation. Example of durability calculation for steam turbine structure member under thermo-cyclic loading is given too.

 

Keywords: thermocyclic strength, pseudo-alpha titanium alloy, original specimen, stress concentrator, fatigue crack, testing, numerical investigation.

 

DEVELOPMENT OF IMPLANTS FOR RIBS OSTEOSYNTHESIS FROM NiTi ALLOY WITH SHAPE MEMORY EFFECT

 

M.Yu. Kollerov, P.A. Korolev, A.A. Sharonov, D.E. Gusev, S.I. Gurtovoy, E.E. Dolgopolova

 

The features of the design, manufacture and use of implantable structures made of alloys based on titanium nickelide, which have a shape memory effect and superelasticity, are considered. The relationship between the capacity for work characteristics of implants and the functional properties of the material - critical strains in the martensitic and austenitic state is shown. The analysis of technical tests and clinical application of individual implants for rib osteosynthesis was carried out.

 

Keywords: NiTi alloy, shape memory effect, critical strains, implants, osteosynthesis, ribs.

 

INVESTIGATION OF WEAR AND CONCENTRATION OF METAL IONS AFTER IMPLANTATION OF GROWTH GUIDANCE INSTRUMENTATION MADE OF Ti6al4v TITANIUM ALLOY FOR THE TREATMENT OF CHILDREN'S SCOLIOSIS

 

E.A. Lukina

 

In this work, a quantitative evaluation of the volumetric wear of LSZ-4D growth guidance sliding instrumentation used for the surgical treatment of scoliosis in children was carried out. Devices retrieved 6±2 years after implantation were studied. It was found that the volume wear rate of LSZ-4D device was found to be 12.5 mm3 per year from which 5 mm3 per year is the rods wear debris and 7.5 mm3 per year is the contribution of fixtures. The content of titanium and vanadium ions in the whole blood of patients after 6 years after implantation increased 2.8 and 4 fold, respectively. An increase in the concentration of metal ions in the tissues surrounding the implant is also found. The results indicate that the application of wear resistant coatings on Ti components in growth guidance sliding devices for treatment of early on-set scoliosis will be useful.

 

Keywords: titanium alloy, wear, implant, scoliosis, metal ions.