de la Hoz, Maria Florencia TanoSanchez, Andrea GomezMariscotti, ValentinaProcaccini, Raul...
8页
查看更多>>摘要：The effect of functionalization of anodized zirconium (Zr) with RGD peptides on cell behavior as a feasible approach to stimulate early bone integration is presented. The surface modifications were evaluated by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Electrochemical tests were performed to determine the effect of functionalization on the stability of the anodized zirconium oxide film. Finally, the biocompatibility of the material was evaluated in an in vitro cell model. Surface analysis showed the presence of peptides on the surface after functionalization, and that the crystal structure of the oxide formed by anodization is predominantly monoclinic. The immobilization of RGD peptides on anodized Zr does not alter the corrosion protection provided by the anodic oxide and significantly promote cell adhesion and spreading in vitro. Thus, the combination of RGD peptides with anodic oxide on Zr surface would represent a useful strategy to increases the biocompatibility of the material.
Alves, S. A.Fernandez-Lopez, P.Lopez-Ortega, A.Fernandez, X....
18页
查看更多>>摘要：Aluminum-silicon (Al-Si) alloys have been increasingly used in several industries to develop novel lighter and high-performance components. Nevertheless, these novel advanced materials display poor wear resistance which hamper their application in several critical tribological components. This investigation is focused on the surface modification of Al-Si alloys with high Si content, through a breakthrough green coating technology named plasma electrolytic oxidation (PEO). The main aim is, for the first time, to study the tribological behavior of PEO-treated cylinder liners made of cast Al with high Si content, in a configuration mimicking the real contact between a cylinder liner and a piston ring. Additionally, this study is based on the development of a novel electrolyte especially designed to generate PEO films with improved tribological properties.& nbsp;Novel films were successfully synthesized by PEO in an innovative aluminate-based electrolyte. The morphological, topographical, and chemical features of the films were assessed through scanning electron microscopy (SEM), thickness and average roughness (R-a) measurements, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Cross-sectional SEM images showed that PEO films developed in the novel electrolyte are denser and thicker. Additionally, the novel PEO-treated cylinder liners, presented a significantly improved resistance to wear damage when submitted to tribological actions simulating the cylinder liner/piston ring real contact movements, which was linked with the extremely higher hardness of the films. These cylinder liners presented a lower COF compared to the commercial reference, along the whole duration of sliding. Finally, tribological tests showed that PEO-treated Al cylinder liners displayed a similar level of mechanical wear damage that steel cylinder liners.& nbsp;The results presented in this investigation envisage the feasibility of PEO to be applied on Al-Si engine components submitted to aggressive tribological conditions, enhancing their durability requirements to levels similar to components made of steel.
Chen, XiTiamiyu, Ahmed A.Schuh, Christopher A.LeBeau, James M....
7页
查看更多>>摘要：Successful cold spray processing requires the formation of metallurgical bonds at the interface between particle impact sites and the substrate. While surface contamination on either the particle or substrate can interfere with metallurgical bonding, the details of particle/substrate interface chemistry are usually obscured or lost during the nanoseconds-long particle impact process. To provide a direct, detailed account of particle-substrate interfacial chemistry, we perform post-mortem scanning transmission electron microscopy and spectroscopy of impact sites of single copper microparticles, launched with a laser-induced particle impact tester, on a copper substrate. In addition to native oxides, we find that amorphous carbon and spherical copper oxide dispersoids are also present near/at the interface. Further, these features are found to influence metallurgical bonding. These results offer additional considerations for optimizing the quality of the cold spray deposition process.
查看更多>>摘要：To improve the corrosion resistance of the Ti-6Al-4V alloy treated by micro-arc oxidation (MAO), molybdenum disulfide (MoS2) particles were added into the electrolyte and a composite oxide coating was formed with different MoS2 contents on the surface of Ti-6Al-4V alloy. A scanning electron microscope and a handheld roughness meter were used to analyze the surface morphology and roughness of the coating, and the corrosion performance of the MAO-treated Ti-6Al-4V alloy was analyzed by galvanic corrosion meter and electrochemical workstation. The results show that MoS2 can be successfully incorperated into the coating and block the micropores during the process of micro-arc oxidation. Electrochemical experiments showed that the coating has a higher resistance and a lower corrosion rate, while in the galvanic experiment, the galvanic potential and galvanic current of the coating also decreased. Under the experimental conditions, the addition of MoS2 can significantly improve the corrosion resistance of the MAO coating, and the best corrosion resistance is obtained when the addition amount is 4g/L, this will expand the marine applications of Ti-6Al-4V alloy.& nbsp;
查看更多>>摘要：Plasma spray coating properties frequently depend-to a great extent-on the spray parameters. However, it is difficult to analyze and obtain a comprehensive model of the entire plasma spray process due to the complex chemical and thermodynamic reactions that take place during the process. In this study, Ni60CuMo coatings were prepared on ZL109 substrates. A Back Propagation (BP) Neural Network model in the artificial neural network was used to predict the change in bonding strength, microhardness, and porosity of the coatings under different spraying distances, spraying powers, and powder feeding rates. The results show that the R-value of the trained network training is 0.8828. Comparison of experimental and predicted results reveals that both show similar trends, which verifies that the BP model can effectively predict the properties of Ni-based coatings.
查看更多>>摘要：Molybdenum disulfide (MoS2) is used extensively in aerospace applications, where liquid lubricants are not suitable. MoS2 has excellent tribological properties in vacuum, however, further research is required to fully understand the mechanisms taking place when exposed to varying temperatures in ambient atmosphere due to storage and on-ground testing. MoS2 coatings were deposited on AISI 440C steel substrates, friction and wear tests were conducted at increasing temperatures, up to 75 ?degrees C, determining the effect of temperature on wear mechanisms in air. It was found that the detected surface oxides do not impact tribological properties in MoS2 at temperatures around 75 ?degrees C. The water molecules at room temperature hinder the alignment of MoS2 layers leaving some active edge sites exposed to contacting surfaces, leading to high friction and wear. Desorption of water molecules promote parallel alignment of layers, reducing shear strength, friction and wear.
查看更多>>摘要：The present study estimates the corrosion and wetting properties of sputter deposited osbornite titanium nitride (O-TiN) coating onto a stainless steel (SS-304). The wettability, surface morphology, chemical composition and corrosion characteristics of the treated samples were studied in detail. The performances of the O-TiN@SS-304 coating were compared to polished SS-304 substrate. The results show that the nano-cluster growth of O-TiN coating alter the hydrophilic surface (theta(w) similar to 78.2 degrees) of SS-304 into hydrophobic surface (95.41, which promote the aqueous passivation behavior. The corrosion testing for a long-term immersion (6 h) illustrated that the coated sample shows greater corrosion resistance than the SS-304. This greater corrosion resistance is accountable for low degree of corrosion rate of around 16.7 x 10(-3) mm/year of the coated sample. Therefore, the O-TiN nanocluster coating with a homogeneously ordered hydrophobic surface is projected as a long-lasting, stable and corrosion resistive for industries, when immersed in salinity media [3.5% NaCl] and useful for extending the protecting applications in other relevant material fields.
NSTL
Elsevier