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Biomaterials for hip implants – important considerations relating to the choice of materials

Choroszyński M., Choroszyński M. R., Skrzypek S. J.

Bio-Algorithms and Med-Systems

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2017

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Vol. 13, no. 3

133--145

EN

This article is a review of important material requirements for hip biomaterials including their response to the body environment (biocompatibility), mechanical properties, wear resistance, fretting corrosion and availability as well as the price. The application of proper biomaterials for hip implants is one of the major focal points in this article. Background information is also provided on metals used in other prosthetic devices and implant components. Titanium and its alloys, cobalt base alloys and stainless steels (bio-steels) are used for load-bearing hip implants. These three groups of metallic materials will be introduced and discussed in detail. Metals and their alloys are crystalline materials since their properties depend on the crystal lattice, chemical and phase compositions, grain size, lattice defects, crystalline texture and residual microand macro-stresses. All these features of biomaterials are formed during technological manufacturing, such as metallurgical process, solidification, plastic deformation (rolling and forging), machining, heat treatment and coating. All these technological processes work in optimal conditions in order to achieve the optimal microstructure and mechanical, chemical and biological properties. Amongst the above-mentioned particular properties of biomaterials, fretting is a major concern as regards hip implants at the femoral head and neck taper interface. Additional important mechanisms of interaction between the implant and the human body must be taken into account, i.e. diffusion stream of foreign particles and atoms from the implant to body fluids, to the tissue and to the bone. These foreign particles and atoms are released from the implant to the body fluid, to the tissue and to the bone as wear product during use. All together they contribute to the wear, i.e. loss of weight, strength or volume of hip components. Wear rates of ultrahigh molecular weight polyethylene mated against Ti-6Al-4V are significantly greater than the ones for Co-Cr-Mo alloys. Therefore, thermochemical surface treatments like diffusion ion nitriding should be applied to increase the resistance of titanium alloys to wear. Austenitic stainless steels are also used for temporary applications, but they have lower resistance to pitting corrosion than titanium and cobalt alloys. The purpose of the paper is to introduce a group of metallic materials, which is often chosen for surgical hip implants. Conclusions of the paper refer to information which support important medical and patient decisions on hip implants. Also, the development of biomaterials, their treatments, properties, surface layers and coatings are considered. All these features develop over time and need synergy and experience in the progress of the biomedical, mechanical and materials science.

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Analiza fazowa złączy superstopów niklu ze stalą austenityczną lutowanych próżniowo

Skrzypek S. J., Goły M., Dul I., Babul T., Korzeń T., Choroszyński M.

Przegląd Spawalnictwa

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2013

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R. 85, nr 8

41--44

PL

Wysokotemperaturowe lutowanie próżniowe jest szeroko stosowane do metali i stopów pracujących w warunkach żaroodporności i żarowytrzymałości, które często zawierają powierzchniowe tlenki trudno ulegające dysocjacji. Dotyczy to superstopów zawierających Ni i Al, tworzące trwałe warstewki tlenkowe. Próżnia lub kontrolowana atmosfera służą do przeciwdziałania tworzeniu się tlenków i sprzyjają ich termicznej dysocjacji. Przed procesem lutowania wszystkie części muszą podlegać wstępnej obróbce oczyszczania powierzchni z powłok, smaru, oleju i z drobinek jakichkolwiek obcych substancji. Zastosowano i omówiono próżniowe lutowanie super stopu Inconel 625 (X10NiNbCoAl58-4) z elementami ze stali austenitycznej (X10CrNiMn20-10-2) przy ciśnieniu ok. 1,3•10-2 Pa. Materiał lutowniczy (NiCrSiBFe) w formie folii o grubości 0,1 mm miał strukturę amorficzną. Po procesie lutowania struktura lutowia uległa przebudowie na fazy krystaliczne.

EN

The high temperature vacuum brazing is widely used in joining metals and alloys applied in high temperature loading machine parts. It is important particularly for alloys with surface layers of oxide, resistant to dissociation. Among them such materials as super alloys containing Ni and Al which easy crate stable layer oxides. Metal parts before brazing should have removed oxides, solid and mineral particles such as oil and grease. In this paper some examples of brazing of Inconel 625 samples and austenitic stainless steel in aspect of metallography and phase composition are introduced. Brazing material in a form of foil 0.1 mm thick composed with NiCrSiBFe was in amorphous state. The joining plates 1 mm thick made of join alloys were annealed, mechanically prepared and cleaned. The brazing process was in vacuum at the pressure of 11,3•10-2 Pa. After solidification and cooling with furnace the brazing material appeared in specific metallographic and phase structure.

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Structure and mechanical properties of Al-Li alloys as cast

Augustyn-Pieniążek J., Adrian H., Rzadkosz S., Choroszyński M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

5--10

EN

The high mechanical properties of the Al-Li-X alloys contribute to their increasingly broad application in aeronautics, as an alternative for the aluminium alloys, which have been used so far. The aluminium-lithium alloys have a lower specific gravity, a higher nucleation and crack spread resistance, a higher Young’s module and they characterize in a high crack resistance at lower temperatures. The aim of the research planned in this work was to design an aluminium alloy with a content of lithium and other alloy elements. The research included the creation of a laboratorial melt, the microstructure analysis with the use of light microscopy, the application of X-ray methods to identify the phases existing in the alloy, and the microhardness test.