No abstract

Surfaces featuring hydrophobic behaviour are generally prepared by a wide spectrum of technologies featuring different process complexity (anodic oxidation, lithography, electrodepositing, etc.). The aim of the work was to use a relatively simple method of magnetron sputtering to prepare metallic hydrophobic surface. Chromium coatings were selected due to their high adhesion to steel and corrosion resistance while conserving certain level of hardness and ductility. The tested coatings included pure Cr and pure Cr with CrN interlayer. The resulting contact angle value of up to 111°has confirmed hydrophobic behaviour. The resulting surface morphology is formed by almost perfectly developed crystals in the shape of hexagonal pyramids providing a suitable surface roughness conditions for hydrophobicity.

In the case of titanium alloys, the oxide layers on their surfaces strongly influence biocompatibility and corrosion resistance. To improve these characteristics, properties of oxide layers prepared by various methods on different base materials were examined. In this work, samples of widely used biomaterials, CP titanium grade 2 and alloy Ti6Al4V, were compared with recently developed β‐titanium alloy Ti‐39 wt% Nb. On the samples from these materials, the thermal (600°C/8 hr/atmospheric air) and anodic (1‐M H2SO4/100 V/1 hr) oxide layers were prepared. The change of surface color was observed. The surface topography of oxidized samples was observed using scanning electron microscopy. The thickness of oxide layers was measured and observed on the cross‐sectional samples. The further analysis of oxide layers surfaces was conducted using X‐ray photoelectron spectroscopy and atomic force microscopy. The growth of hydroxyapatite for further comparison of oxide layers was realized in Hank' balanced salt solution.

Carbon fiber composite laminates (CFRP) used in aerospace are operating under various environmental conditions. Parts are often exposed to moisture which slowly diffuses into the laminate and forms internal stresses. During the flight, the aircraft is also exposed to low or elevated temperatures. The result is negative impact on composite performance due to formation of hygrothermal stresses. Understanding this phenomenon helps with prediction of the damage development which is vital for increasing the components service life. The open‐hole CFRP laminates were conditioned in humid air at 70°C/85% RH for 33,800 h and the effect of low temperatures on quasi‐cyclic tension properties and fracture behavior was investigated. The mechanical tests on two types of CFRP laminate with different number and orientation of plies were performed under − 55°C. The material behavior during the testing was monitored by acoustic emission technique. The light optical microscopy and scanning electron microscopy were used for the identification of failure mechanisms. The study showed that the hygrothermal effect has significant impact on materials toughness reduction. The damage mechanisms and characteristic morphologic features are changing due to the matrix degradation and weakened fiber/matrix interface.

Oxide layers on titanium alloy surfaces have an influence on bio-compatibility and corrosion resistance. In order to improve them, properties of oxide layers are examined. The oxide layer can be prepared by different methods and under various conditions. This results in a creation of layers showing different composition, structure, properties, stability, adhesion and biocompatibility. In the presented paper, samples of three titanium alloys were used: Commercially Pure (CP) titanium grade 2, Ti6Al4V alloy and -titanium alloy Ti-39 wt.% Nb. Samples were anodically (1MH2SO4 / 100V/ 1 hour) oxidized. Changes in surface colouration and roughness were observed. The thickness of oxide layers was measured using a scanning electron microscope (SEM). The SEM was then used for observation of the surface topography of oxidized samples. The chemical composition of the surface layers was defined by X-ray photoelectron spectroscopy (XPS).