A. Radziszewska

Influence of polyetheretherketone coatings on the Ti–13Nb–13Zr titanium alloy's bio-tribological properties and corrosion resistance

Polyetheretherketone (PEEK) coatings of 70-90μm thick were electrophoretically deposited from a suspension of PEEK powder in ethanol on near-β Ti-13Nb-13Zr titanium alloy. In order to produce good quality coatings, the composition of the suspension (pH) and optimized deposition parameters (applied voltage and time) were experimentally selected. The as-deposited coatings exhibited the uniform distribution of PEEK powders on the substrate. The subsequent annealing at a temperature above the PEEK melting point enabled homogeneous, semi-crystalline coatings with spherulitic morphology to be produced. A micro-scratch test showed that the coatings exhibited very good adhesion to the titanium alloy substrate. Coating delamination was not observed even up to a maximal load of 30N. The PEEK coatings significantly improved the tribological properties of the Ti-13Nb-13Zr alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.40 and 0.12 for a coated alloy in a dry sliding and sliding in Ringers solution, respectively. The PEEK coatings exhibited excellent wear resistance in both contact conditions. Their wear rate was more than 200 times smaller compared with the wear rate of the uncoated Ti-13Nb-13Zr alloy. The obtained results indicate that electrophoretically deposited PEEK coatings on the near-β titanium alloy exhibit very useful properties for their prospective tribological applications in medicine.

The Microstructure of Weld Overlay Ni-Base Alloy Deposited on Carbon Steel by CMT Method

Ni-base alloys, like Inconel 625, exhibit a high temperature corrosion and oxidation resistance. For this reason, these alloys are typically used as a one of the most important coating material and can be applied in a different environments and elements of devices having various applications. In this work, Inconel 625 was deposited onto a carbon steel P235GH by Cold Metal Transfer method. Due to the segregation of Ni, Cr, Nb and Mo elements the Inconel 625 weld overlays cladded on boiler pipes P235GH obtained the dendritic structure, with the formation of a second phases at the end of solidification. The presence of γ (with high dislocation density), the Laves and (Nb,Ti)C phases was revealed by means of TEM examinations. The multipoint EDS analysis confirmed the presence of low Fe concentration in the Inconel 625 alloy coatings. The concentration profiles of Ni, Cr, Mo and Nb performed across the dendritic structure showed segregation of these elements.

Microstructure and properties of laser interference crystallized amorphous FeSiB ribbon

Abstract The influence of Q-switched pulsed Nd:YAG laser interference heating, using 120 mJ of pulse energy and a variable number of consecutive pulses, on the microstructure and magnetic properties of amorphous Fe80Si11B9 alloy was examined. Microstructural analysis, using light, scanning and transmission electron microscopy, was complemented by results of Mössbauer spectroscopy and measurement of magnetic properties (vibrating sample magnetometer). Periodically distributed crystallized micro-areas, ∼10 μm in diameter, in an amorphous matrix were produced by the treatments. Magnetization measurements showed that the as-cast ribbon and laser light irradiated samples are magnetically soft materials. The results lead to the conclusion that the dots corresponding to the laser modified regions exhibit a perpendicular magnetic anisotropy.

Structure and Morphology of Thin Films Deposited by Pulsed Laser Deposition Technique

The paper presented the structure (TEM), morphology and chemical composition (EDS) of the -Al-Mg thin films and Al-Mg-Ni multilayer obtained by pulsed laser deposition (PLD). This films were deposited using Nd:YAG laser. The different process parameters were applied. The Al-Mg film was obtained by application of the laser wavelength (=355 nm) and substrate temperature (Ts) 200 oC. Whereas the Al-Mg-Ni multilayer was produced at lower laser wavelength (=266 nm) and at room temperature of the substrate. For preparation of both films the same laser fluence (q=4.7 J/cm2) was used. The Al-Mg possessed nanocrystalline structure with the areas where only columnar Al crystals occurred. EDS of this thin film exhibited that in the nanocrystalline areas the chemical composition corresponded to the target content of Al and Mg. While Al-Mg-Ni multilayer composed of six layers. In this case Al-Mg layers were thinner then Ni layers. In the multilayer structure the fcc Al0.65Mg0.35 and fcc Ni phases was revealed.

Modification of Al-Si alloy surface layer using Nd: YAG laser

The paper describes the laser cladding of hypereutectic Al-Si alloy with chromium. An impulse Nd:YAG laser was employed for laser cladding process. The article presents the changes of microstructure, chemical composition, microhardness of the obtained clad layers, which were depended on the effect of the laser processing parameters and the thickness of chromium coatings. The laser cladding produced the very fine microstructure and higher hardness of clad layers.

Al-Cu-Fe thin films deposited by PLD technique

In this paper the results of the investigations of Al-Cu-Fe surface layers deposited by PLD technique are presented. The study was carried using different parameters of process. The morphology and chemical composition of obtained surface layers was examined. In the frames of the investigations the oxidation resistance tests of the Al-Cu-Fe layers was performed. The results indicate that it is possible to apply obtained layers as oxidation barrier.