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A. Zielinski and S. Sobieszczyk

NANOTECHNOLOGIES IN DEVELOPMENT OF STRUCTURAL MATERIALS AND BIOMATERIALS

The nanometric materials and technologies resulted in nanostructures are reviewed. The examples of nanomaterials are shown. The typical nanotechnologies, including plastic deformation, mechanical attrition, controlled detonation, hot plasma jet synthesis, laser vaporisation, CVD and PVD, mechanical milling, annealing, ultrasonic irradiation, nanolithography, electrocrystallisation, electrospinning, sol-gel method, cryogenic laser-enhanced melting, and hydrogen-enhanced amorphisation, are presented. Typical applications in technics and medicine are given.

Open access

S. Sobieszczyk and A. Zieliński

Coatings in Arthroplasty: Review Paper

The modern coatings used in arthroplasty for long term implants are reviewed. The phosphate coatings are the most popular technique to improve the bone-implant interfacial strength and promote the osseointegration. The plasma spraying, electrophoretic precipitation, powder metallurgy, ion beam sputtering, high velocity oxy-fuel (HVOF) combustion spraying, sol-gel technique, biomimetic deposition are mostly used to obtain the phosphate, usually hydroxyapatite coatings.

The composite coatings based on HA are proposed to improve biochemical and mechanical properties. The Ti, Ti alloys, titania, zirconia, zinc particles and glasses are suggested to strengthen the HA matrix, and some organic compounds and polymers to improve the biochemical behaviour.

Among another coatings, titania, zirconia, aluminia, carbon and organic, glass - ceramics and titania - silicate coatings are mostly proposed.

Open access

A. Ossowska, A. Zieliński and M. Buczek

Properties of Surface Layers of Titanium Alloy TI6AL4V After Laser Melting Processes

The article presents the investigation results of titanium alloy Ti6Al4V surface layer after laser melting process. The process of laser melting was performed using Nd-YAG laser. The evaluation of structure of the alloy as well as hardness and chemical composition was performed. It was shown that laser melting changes the structure and properties of titanium alloy Ti6Al4V and process parameters as scanning speed affects the thickness of zones in top layer of the material. Due to the laser melting process more wear resistive surface can be obtained that increases the wear and corrosion resistance of orthopeadic prosthesis.

Open access

T. Seramak, W. Serbiński and A. Zieliński

POROUS BIOMATERIAL FOR ORTHOPAEDIC IMPLANTS BASED ON TITANIUM ALLOY

Titanium and its alloys are widely used as biomaterials for orthopaedic applications. Research connected with their best corrosion and wear resistance, biocompatibility and bioactivity are still being conducted. The current research is also focused on the design and manufacturing of the porous materials based on e.g. Ti-13Nb-13Zr alloy, which can be applied for implants. One of the most effective manufacturing methods of the porous materials are powder metallurgy techniques. The aim of the presented work was the design of powder preparation procedure and design a parameters of pressing and sintering processes in order to obtain the porous structure from Ti-13Nb-13Zr alloy. Investigation results of the microstructure morphology, pore size and porosity of the obtained porous material on the base Ti-13Nb-13Zr alloy in dependence of the pressing and sintering parameters are also shown and discussed.

Open access

A. Zieliński and G. Golański

Abstract

The aim of the paper was to examine the influence of repair welded joints on the service life of steam pipelines for over 220 000 hours of service in creep conditions. The research included the study of the microstructure using scanning microscopy, the tests on mechanical properties at room and elevated temperature, determining the nil ductility transition temperature, and short-time creep tests to determine the residual life of the material. The tests allowed determining the time of further safe operation of elements of the steam pipeline with a repair welded joint, with reference to the base material, and the welded joint after service. The assessment of residual life and disposable residual life, and at the same time determining the possible time of further safe operation, has an essential meaning in the case of elements serviced considerably beyond the calculated working time.

Open access

A. Zieliński, A. Dziadoń, W. Serbiński and M. Jażdżewska

Surface Cracking of Laser Melted Ti-6Al-4V Alloy

The characteristic features of surface cracking observed after laser melting with CO2 and Nd:YAG laser were described. The cracks were always present, their length approaching some part of melted zone and scarcely dependent on laser melting conditions. The appearance of cracks was attributed mainly to martensitic transformation within the surface layer. The possible contribution of developed thermal stresses cannot be also excluded. The existence of cracks may be utilized for the enhancement of bone - implant strength.

Open access

G. Golanski, A. Zielinski, J. Słania and J. Jasak

Abstract

The paper describes the influence of different times of ageing on mechanical properties and microstructure stability in hardened and tempered VM12 steel exposed to service temperature - 600°C. Detailed microstructural and microchemical analysis of secondary phases was carried out using scanning electron microscopy (SEM + EDX) and X-ray phase analysis of carbide isolates. Performed research has proved high stability of strength properties of the investigated steel, which is connected with the lath stability of the microstructure of tempered martensite. Slight changes in strength properties were accompanied by over 50% reduction in impact strength KV of the examined cast steel, from the level of 83 J in the as-received condition to 38 J after 30 000 hrs of ageing at the temperature of 600°C. Significant decrease in impact energy KV of VM12 steel results from the growth of the amount and size of precipitations on grain boundaries.

Open access

A. Zieliński, W. Serbiński, B. Majkowska, M. Jażdżewska and I. Skalski

Influence of laser remelting at cryogenic conditions on corrosion resistance of non-ferrous alloys

The main reason for laser remelting of the components made of aluminium, copper and titanium alloys is to obtain high hardness and corrosion resistance at the surface for longer lifetime as result of the rapid solidification. The final microstructure, phase composition and properties of aluminium, copper and titanium alloys depend on the laser process parameters and obviously on the nature of the equilibrium system.

The effect of laser surface remelting at cryogenic conditions on the microstructure and corrosion characteristics of the AlSi13Mg1CuNi, SUPERSTON and Ti-6Al-4V alloys are presented. The beneficial effects of laser treatment on the microstructure and corrosion behaviour of those alloys used for different products are observed.

Open access

M. Sroka, A. Zieliński and J. Mikuła

Abstract

This paper presents the evaluation of the service life of dissimilar repair welded joint from Cr-Mo/Cr-Mo-V steel after 200,000 h service under creep condition. The investigations of microstructure using scanning electron microscopy, investigations of mechanical properties at room and elevated temperature as well as creep tests of the basic material from Cr-Mo and Cr-Mo-V steel and welded joint from these steels were carried out. The investigations allowed the time of further safe operation of the repair welded joint in relation to the residual life of the materials to be determined. The evaluation of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is crucial when the elements are operated much beyond the design work time.

Open access

A. Zieliński, M. Miczka and G. Golański

Abstract

The results of investigations on the microstructure of T23 and T24 low-alloy steels as well as P91 and P92 high-chromium steels in the as-received condition and after 70.000 h annealing at 550-650°C are presented. The quantitative analysis of the existing precipitates was performed for representative images of microstructure. The statistical analysis of collected data allowed the parameters of a selected theoretical statistical distribution to be estimated. A forecast of average precipitate diameter and standard deviation of such a distribution for the time of 100,000 hours at 550 and 600°C for T23 and T24 steels and at 600 and 650°C for P91 and P92 steels was calculated. The obtained results of investigations have made it possible to compare changes in the microstructure of various steel grades due to long-term impact of elevated temperature. They have also confirmed the possibility of using, in evaluating the degradation degree of materials in use, the forecasting methods that derive from mathematical statistics, in particular the theory of stochastic processes and forecast by analogy methods. The presented approach allows the development of a forecast of precipitate diameter probability density under the microstructure instability conditions for selected steel grades. The assessment of material condition that takes into consideration, but is not limited to, the precipitate diameter measurement is useful as an assessment component in estimating the time of safe service of power unit elements working under creep conditions.