Project

The production of titanium products for future use in medicine

Goal: The project aims to develop production of cheaper and patient specific medical implants from local titanium in the Republic of Kazakhstan. We pursue two approaches: 1) Implant lathing by numerically controlled machines, followed by surface purification and quality control; 2) Microplasma spraying of biocompatible Ti wires and hydroxyapatite (HA) powders onto implants using an industrial robot. Goal: process optimizing & prototype development. Samples of specific implants were provided by the Kazakhstan Research Institute of Traumatology and Orthopedics

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Project log

D. L. Alontseva
added a research item
This paper presents new results of studying the influence of parameters of microplasma spraying (MPS) of Ti wire on the structure and properties of Ti coatings. Based on the design of the experiment and the results of the SEM study, certain spraying modes were chosen to form the desired composition and structure of the Ti coating. The dense sublayer (up to 300 #x000B5;m thick) provides good adhesion to the substrate, and a porous top layer can accelerate the coated implant ingrowth with the bone. This technology is developed for the manufacture of coated endoprosthesis implants. This article is protected by copyright. All rights reserved
D. L. Alontseva
added 2 research items
The task of controlling the manipulation robot movement in one direction has been considered. Such task appears at cutting, welding, painting and other similar operations, when the robot instrument performs a program motion along the working surface and at the same time, it is necessary to keep a definite distance from this instrument to the surface automatically without excessive correction. A new algorithm of controlling the linear object of the second order of the general form has been obtained by dynamics and perturbations compensation method, which takes precedence over well-known decisions. The algorithm provides a zero static error of the system regulation and movement in acquisition of external effects within the accuracy of standard filters of the second order that is convenient for practical use. The first filter indicates movements of the system during the task performing; the second one provides perturbations compensation on state variables. A step-by-step procedure of the algorithm synthesis has been represented for the second order controlled object of the general form. Formulae for calculating regulator coefficients have been obtained. The obtained equations defining processes in a closed control system allow performing the analysis of the control quality and the dynamics of control changes depending on external influences. A method of equations identification of the robot motion in conditions when we know the maximum speed of its instrument movement and a dynamic error of the robot servosystem regulating has been developed. By this method, the robot equations are brought up to the Vyshnegradskiy’s form and then on the computer model a fundamental frequency and a decay factor can be easily chosen. The application of the obtained algorithm has been reviewed to create a system of automatic regulation of the robot instrument position. It has been clarified that defining free coefficients of these filters on position of filter fundamental frequency equation and a controlled object provides the given system operation speed at moderate amplitude of controlling actions. A mathematical modeling method has shown the advantages of regulation program quality, parametric and structural robustness of the obtained control system.
The motivation for the research was the challenges faced in developing the robotic microplasma spraying technology for applying coatings from biocompatible materials onto medical implants of complex shape. Our task is to provide microplasmatron movement according to the complex trajectory during the surface treatment by microplasma and to solve the problem of choosing the speed of the microplasmatron movement, so as not to cause melting of the coating. The aim of this work was to elaborate mathematical modeling of temperature fields in two-layer heat absorbers: coating-substrate depending on the velocity of microplasmatron with a constant power density. A mathematical model has been developed for the distribution of temperature in two-layer absorbers when heated by a moving source and the heat equation with nonlinear coefficients has been solved by numerical methods.
D. L. Alontseva
added a research item
This paper presents the experimental techniques of transmission electron microscopy of plasma-spray powder alloy coatings. It includes the specimen preparation techniques for powder materials and for plasma spray powder coatings from the nickel-chromium-based alloy and synthetic hydroxyapatite (HA) and the analysis of the results. The study of the structure-phase compositions of HA powders and HA and Ni-Cr-based plasma spray coatings has been carried out by using transmission electron microscopy on JEM-2100 (JEOL), and by X-ray diffraction (XRD) on X’Pert PRO diffractometer (PANalytical, the Netherlands). It has been established that the coatings have the desired structure-phase composition as a result of the selection of specific modes of plasma spraying and additional plasma treatment. The advantages and challenges of application of TEM method for analyzing the structure of thick (up to 300 µm) powder coatings deposited by plasma spraying methods onto metal substrates are investigated.
D. L. Alontseva
added 5 research items
The paper presents the main results of joint research by Ukrainian and Kazakhstani scientists of two-layer titanium and hydroxy-apatite coatings structural-phase composition. The coatings have been deposited onto titanium medical implants using a robot aided complex of microplasma treatment of materials. X-ray structure phase analysis, transmission and scanning electron micros-copy and metallographic analysis were used to study the structure-phase composition of coatings and substrates. The influence of the main parameters of the microplasma spraying on morphology and structure-phase transformations in coatings was studied. The composition and regimes of microplasma spraying two-layer coatings for titanium implants, including a sub-layer of a porous titanium coating with a thickness of 200 ... 300 μm with a pore size of 150 ... 300 μm, and an upper layer of hydroxyapatite with a thickness of up to 200 μm with a high crystallinity (88-98%), controlled by changing the spraying regime are developed. Technological guidelines and software have been developed enabling to implement robot aided microplasma spraying of coatings from biocompatible materials on medical implants. In the future, this will allow implementing new technologies for the production of various types of high-quality and affordable medical implants made of titanium alloys produced in Kazakhstan.
This paper describes the equipment design of E. O. Paton Electric Welding Institute and technology of microplasma spraying of coatings from powder and wire materials for applying biocompatible coatings for medical implants. The given equipment was introduced at an experimental robotics complex for microplasma spraying at D. Serikbayev East-Kazakhstan State Technical University By this example the authors discuss the challenges and prospects of the development and implementation of microplasma spraying technology.
The paper presents the main results of development and optimization of the synthesis of hydroxyapatite and the application of the micro-plasma spraying technique for biocompatible coatings. The hydroxyapatite synthesis was optimized using the mathematical modelling method. Synthesized hydroxyapatite was studied by IR spectrometry and X-ray diffraction analysis for assessment of the compatibility of the chemical and phase composition to the bone tissue. The Ca/P ratio of the obtained hydroxyapatite was 1.65, which is close to that of bone tissue (1.67). To increase the adhesion strength of the HA coating to the surface of the titanium implant, it was suggested to apply a titanium sublayer to the implant surface. Microplasma spraying (MPS) of biocompatible coatings from titanium wires and synthesized HA powders onto substrates made of medical titanium alloy has been carried out. Microplasmatron MPN-004 is used to obtain the two-layer coatings for titanium implants. The two layer coating includes a sub-layer of a porous titanium coating with a thickness in range from 200 up to 300 μm and the porosity level of about 30%, and an upper layer of HA about 100 μm thick with 95% level of HA phases and 93% level of crystallinity. The pore size varies from 20 to 100 μm in both coatings. The paper describes the technology and modes of microplasma deposition of two-layer coatings, including the mode of gas-abrasive treatment of the surface of implants made of titanium alloy before spraying. The synthesized HA powder and the Ti/HA coatings were investigated by optical microscopy and scanning electron microscopy with the energy dispersion analysis and the X-ray diffraction analysis.
D. L. Alontseva
added a project goal
The project aims to develop production of cheaper and patient specific medical implants from local titanium in the Republic of Kazakhstan. We pursue two approaches: 1) Implant lathing by numerically controlled machines, followed by surface purification and quality control; 2) Microplasma spraying of biocompatible Ti wires and hydroxyapatite (HA) powders onto implants using an industrial robot. Goal: process optimizing & prototype development. Samples of specific implants were provided by the Kazakhstan Research Institute of Traumatology and Orthopedics