The aim of this study was to form a functional layer on the surface of titanium (Ti) implants to enhance their bioactivity. Layers of polyurethane (PU), containing hydroxyapatite (HAp) nanoparticles (NPs) and magnesium (Mg) particles, were deposited on alkali-treated Ti surfaces using a cost-effective dip-coating approach. The coatings were assessed in terms of morphology, chemical composition, adhesion strength, interfacial bonding, and thermal properties. Additionally, cell response to the variably coated Ti substrates was investigated using MC3T3-E1 osteoblast-like cells, including assessment of cell adhesion, cell proliferation, and osteogenic activity through an alkaline phosphatase (ALP) assay. The results showed that the incorporation of HAp NPs enhanced the interfacial bonding between the coating and the alkali-treated Ti surface. Furthermore, the presence of Mg and HAp particles enhanced the surface charge properties as well as cell attachment, proliferation, and differentiation. Our results suggest that the deposition of a bioactive composite layer containing Mg and HAp particles on Ti implants may have the potential to induce bone formation.

This study aimed to design an adhesive biodegradable polymer layer on the surface of titanium (Ti) implants for enhanced surface bioactivity. To this end, a coating of magnesium-particles doped biodegradable polyurethane (PU) was introduced as a composite layer on Ti surfaces using a simple spin coating technique. The coating's performance and characteristics were investigated in terms of the surface topography, composition, surface roughness, wettability, adhesion and electrochemical behavior of composite coatings on untreated (polished) and alkaline treated Ti substrates. Interestingly, the Ti samples coated with the composite layers showed superior corrosion resistance compared to the uncoated samples.Additionally, the coating on alkali-treated Ti surfaces demonstrated enhanced adhesion (5B, measured by cross-cut test) compared to the coating on untreated Ti (1B), indicating the vital role of the alkalinetreatment step. A composite thin layer coated on alkaline-treated Ti enhanced osteoblastic-like (MC3T3-E1) cellular adhesion and cell proliferation and was found to support osteoblastic differentiation compared to uncoated alkaline-treated Ti. Surface modification of alkaline-treated Ti with a biodegradable Mg-particles/PU thin layer appears to be a promising strategy for developing surface bioactivity of orthopedic devices. HighlightsPU thin films coated on Ti substrates showed superior corrosion resistance Alkaline treated Ti substrates coated with plain PU film showed better cell attachment and spreading PU coated and alkaline-treated Ti substrates induced the highest adhesion performance Mg particles/PU coated treated Ti can support cell proliferation and differentiation

High phosphorus gray iron (HPGI) is used to secure the steel stub of an anode rod to a prebaked anode carbon block in the aluminium reduction cells. During this work, a detailed characterization for HPGI was done. The variation in the chemical composition of the HPGI collar, anodic voltage drop, and collar temperature over the 30 days anode life cycle were studied and compared with HPGI microstructure at different stages of the experiment. The carbon content in HPGI during anode life cycle was reduced from 3.73 to 3.38%. Significant changes in the HPGI microstructure were observed after 3 and 30 days from the anode changing. The collar temperature increases over the anode life cycle and reaches to 850°C in four weeks after anode changing. Different changes in the anodic voltage drop values at the stub-collar-anode connection during anode life cycle were recorded.Two bench-scale experimental set-ups were designed and implemented to simulate the operating conditions in the steel stub/ HPGI collar/ anode block connection and used to measure the electrical resistance and resistivity respectively. Comparison with steel electrical resistivity showed the greatest importance to modify the current HPGI or producing new alloys with excellent electrical and mechanical properties. The steel stub and HPGI thermal expansion were measured and studied. Considerable permanent expansion was observed for the HPGI collar after the completion of the heating-cooling cycle.

In the oil, gas and petrochemical industries the greatest costs are those associated with material failures due directly to corrosive-erosive degradation of surfaces and components of the pipelines. These results in the frequent repair and replacement of parts which accrues costs associated with loss in revenues in downtime and maintenance [1]. In the current study, a dip-coating method was exploited to provide a coating layer of epoxy resin on 316L and 304 stainless steel plate. Epoxy resin was converted to cationic tertiary type amine resin. This cationic epoxy resin, which contains ammonium group in the end of the polymer chain, was synthesized by ring-opening reaction of an epoxy resin with secondary amine in the presence of a proton donor. A layer of resin was successfully deposited on the stainless steel plates and physical properties of the layer were assessed. A detailed study aiming to obtain reliable information of coating properties was carried out. The electrochemical corrosion results showed that epoxy layer has a positive behavior on protections of stainless steels alloys at the early degradation time point. Scanning electron microscopy observation was also used to study the surface morphology before and after coating. Tafel extrapolation method and Tafel slope constants were used to calculate the polarization resistance.