scholarly journals Durability of Lubricated Icephobic Coatings under Various Environmental Stresses

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 303
Author(s):  
Valentina Donadei ◽  
Heli Koivuluoto ◽  
Essi Sarlin ◽  
Petri Vuoristo
Keyword(s):  
Surface Roughness ◽  
Uv Irradiation ◽  
Structural Changes ◽  
Colour Change ◽  
Cottonseed Oil ◽  
Environmental Stresses ◽  
Flame Spray ◽  
Corrosive Media ◽  
Spray Method ◽  
A Current

Icephobic coatings interest various industries facing icing problems. However, their durability represents a current limitation in real applications. Therefore, understanding the degradation of coatings under various environmental stresses is necessary for further coating development. Here, lubricated icephobic coatings were fabricated using a flame spray method with hybrid feedstock injection. Low-density polyethylene represented the main coating component. Two additives, namely fully hydrogenated cottonseed oil and paraffinic wax, were added to the coating structure to enhance coating icephobicity. Coating properties were characterised, including topography, surface roughness, thermal properties, wettability, and icephobicity. Moreover, their performance was investigated under various environmental stresses, such as repeated icing/deicing cycles, immersion in corrosive media, and exposure to ultraviolet (UV) irradiation. According to the results, all coatings exhibited medium-low ice adhesion, with slightly more stable icephobic behaviour for cottonseed oil-based coatings over the icing/deicing cycles. Surface roughness slightly increased, and wetting performances decreased after the cyclic tests, but chemical changes were not revealed. Moreover, coatings demonstrated good chemical resistance in selected corrosive media, with better performance for paraffin-based coatings. However, a slight decrease in hydrophobicity was detected due to surface structural changes. Finally, paraffin-based coatings showed better resistance under UV irradiation based on carbonyl index and colour change measurements.

Structures of Orthorhombic and Cubic Dicadmium Stannate by Rietveld Refinement

1990 ◽  
Vol 5 (1) ◽  
pp. 36-40 ◽  
Author(s):  
M.E. Bowden ◽  
C. M. Cardile
Keyword(s):  
Detection Limit ◽  
Spinel Structure ◽  
Structural Changes ◽  
Colour Change ◽  
Rietveld Analysis ◽  
Hydrogen Gas ◽  
X Ray ◽  
Uniform Contraction ◽  
Reitveld Analysis ◽  
Diffraction Patterns

AbstractThe structures of orthorhombic (a=5.5686(2)Å, b=9.8946 (2)Å, c=3.19369(12Å) and cubic (a=9.177(3)Å) Cd2SnO4were refined by Rietveld analysis of X-ray powder diffraction patterns. Both of these polymorphs were chemically treated with hydrogen gas mixtures at 400°C, resulting in a colour change from yellow to green. Small structural changes were observed for the orthorhombic material, which underwent a uniform contraction (≈0.02%) of cell size and movement of some oxygen atoms towards the tin atoms. Evidence for loss of structural oxygen was sought, but could not be found above the detection limit of 0.3%. Cubic Cd2SnO4possesses the spinel structure with a large (at least 65%) degree of inversion. Samples prepared with a smaller cell have so far proved unsuitable for Reitveld analysis.

scholarly journals Surface Functionalization of Three Dimensional-Printed Polycaprolactone-Bioactive Glass Scaffolds by Grafting GelMA Under UV Irradiation

2020 ◽  
Vol 7 ◽  
Author(s):  
Farnaz Ghorbani ◽  
Melika Sahranavard ◽  
Zohre Mousavi Nejad ◽  
Dejian Li ◽  
Ali Zamanian ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Roughness ◽  
Surface Modification ◽  
Bioactive Glass ◽  
Uv Irradiation ◽  
Three Dimensional ◽  
Homogeneous Distribution ◽  
X Ray ◽  
Fused Deposition ◽  
3D Printed

In this study, bioactive glass nanoparticles (BGNPs) with an average diameter of less than 10 nm were synthesized using a sol-gel method and then characterized by transmission electron microscopy (TEM), differential scanning calorimetric (DSC), Fourier transforms infrared spectroscopy (FTIR), and x-ray spectroscopy (XRD). Afterward, three dimensional (3D)-printed polycaprolactone (PCL) scaffolds along with fused deposition modeling (FDM) were incorporated with BGNPs, and the surface of the composite constructs was then functionalized by coating with the gelatin methacryloyl (GelMA) under UV irradiation. Field emission scanning electron microscopy micrographs demonstrated the interconnected porous microstructure with an average pore diameter of 260 µm and homogeneous distribution of BGNPs. Therefore, no noticeable shrinkage was observed in 3D-printed scaffolds compared with the computer-designed file. Besides, the surface was uniformly covered by GelMA, and no effect of surface modification was observed on the microstructure while surface roughness increased. The addition of the BGNPs the to PCL scaffolds showed a slight change in pore size and porosity; however, it increased surface roughness. According to mechanical analysis, the compression strength of the scaffolds was increased by the BGNPs addition and surface modification. Also, a reduction was observed in the absorption capacity and biodegradation of scaffolds in phosphate-buffered saline media after the incorporation of BGNPs, while the presence of the GelMA layer increased the swelling potential and stability of the composite matrixes. Moreover, the capability of inducing bio-mineralization of hydroxyapatite-like layers, as a function of BGNPs content, was proven by FE-SEM micrographs, EDX spectra, and x-ray diffraction spectra (XRD) after soaking the obtained samples in concentrated simulated body fluid. A higher potential of the modified constructs to interact with the aqueous media led to better precipitation of minerals. According to in-vitro assays, the modified scaffolds can provide a suitable surface for the attachment and spreading of the bone marrow mesenchymal stem cells (BMSCs). Furthermore, the number of the proliferated cells confirms the biocompatibility of the scaffolds, especially after a modification process. Cell differentiation was verified by alkaline phosphatase activity as well as the expression of osteogenic genes such as osteocalcin and osteopontin. Accordingly, the scaffolds showed an initial potential for reconstruction of the injured bone.

An Investigation about the Effect of Depth of Cut on Surface Integrity in Creep Feed Grinding of INC 792-5A

2011 ◽  
Vol 320 ◽  
pp. 163-169
Author(s):  
R. Ashofteh ◽  
A. Rastkerdar ◽  
S. Kolahdouz ◽  
A. Daneshi
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Structural Changes ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Cutting Depth ◽  
Creep Feed Grinding ◽  
Creep Feed ◽  
Micro Cracks ◽  
Average Grain Size

Creep-Feed Grinding(CFG) is one of the none-traditional machining in which form grinding to full depth is performed in limited number of passes. One of the most significant criteria which is taken into account to display valid machining parameters, is surface integrity. Surface integrity in CFG process is influenced by four main factors including surface roughness, superficial micro-crack, burning and changes in micro-hardness. According to prior investigations in CFG process, depth of cut plays an important role in surface integrity. In this study, the influence of cutting depth on workpiece surface integrity of cast nickel-based superalloy with alummina wheels, was investigated. During this study, a sample part was machined with variable depth of cut while the other parameters were Constant. After machining, surface roughness of each specimen was measured and in order to investigate existence and dimensional situation of surface micro-cracks, Chemical Etch + FPI and Thermal shock + FPI were performed. For determining micro-structural changes in ground specimens as a clarifier criteria in measuring the level of residual stress, a set of recrystallization processes were carried out on them and average grain size were measured. The results show, however, changing in depth of cut hasn't influenced on micro-cracks, quality of surface roughness has descended in terms of increasing the cutting depth.

Research on Thermal Spray Al-Al2O3/TiO2 Coating and Diffusion Treatment on Magnesium Alloy

2006 ◽  
Vol 532-533 ◽  
pp. 217-220
Author(s):  
Hong Ye ◽  
Zhong Lin Yan ◽  
Zhi Fu Sun ◽  
Ying Wang
Keyword(s):  
Magnesium Alloy ◽  
Thermal Shock ◽  
High Hardness ◽  
Flame Spray ◽  
Diffusion Treatment ◽  
Az91d Magnesium Alloy ◽  
Spray Method ◽  
Shock Resistance ◽  
And Diffusion ◽  
Electronic Microscope

Flame spray method was used to prepare the Al-Al2O3/TiO2 gradient coating on AZ91D magnesium alloy surface, where diffusion treatment for 2 hours at 380～420 °C was needed to reinforce the binding strength between the coating and the substrate. Appearance and compositions of the coating were analyzed by scanning electronic microscope (SEM) and electron probe microanalysis (EPMA), and the thermal shock resistance and wear resistance of the coating were tested. The result shows: Al-Mg diffusion is produced between the coating and the substrate, for good metallurgy; coating acquires high hardness and resistant to wear and thermal shock.

Structural Changes in TiO2 Films Formed by Anodizing of Electro-Polished Titanium

2016 ◽  
Vol 869 ◽  
pp. 689-692
Author(s):  
Patricia López Díaz ◽  
Marinalda Claudete Pereira ◽  
Eduardo Norberto Codaro ◽  
Heloisa Andréa Acciari
Keyword(s):  
Surface Roughness ◽  
Raman Spectroscopy ◽  
Surface Modification ◽  
Direct Current ◽  
Structural Changes ◽  
Polarized Light ◽  
Applied Potential ◽  
Granular Microstructure ◽  
Crystalline Films ◽  
Modification Technique

Anodizing is a surface modification technique that is applied to growing oxide films on Ti to accelerate the osseointegration of an implant. Besides the surface roughness, the crystalline structure of these films can affect its performance as a biomaterial. For this reason, this technique has been refined to produce crystalline films without requiring heat treatments. For this purpose, TiO2 films were grown on Ti (grade 2) by anodizing with direct current at different potentials. Images obtained by optical microscopy with polarized light revealed a granular microstructure in various colors, as consequence of different crystalline orientations of the grains and films thickness. Raman spectroscopy showed that the films crystallinity is affected by variations in the applied potential and anodizing time.

scholarly journals Study of Aluminum Influence on the Adhesion of Stainless Steel in Flame Spraying

2020 ◽  
Vol 245 ◽  
pp. 591-598
Author(s):  
Sergey Stepanov ◽  
Tatyana Larionova ◽  
Sergey Stepanov
Keyword(s):  
Surface Roughness ◽  
Adhesion Strength ◽  
Roughness Parameter ◽  
Flame Spraying ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Flame Spray ◽  
Surface Adhesion ◽  
Comparative Results ◽  
Steel Substrates

This paper is dedicated to a study of aluminum influence on the improvement of surface adhesion strength. The main purpose of this work is to investigate the strength of adhesion to the substrate by mixing flame spray powder with aluminum, which not only possesses high corrosion resistance and conductivity, but also provides additional strength, as it combines and reacts with other components of the powder. Research results of sandblasting dependence on surface roughness parameter Ra are demonstrated. The paper describes authors’ original device for a measuring instrument “Profilometer”, which was also used for measuring roughness parameter in order to obtain comparative results. Authors present results of adhesion measurements given obtained values of surface roughness by mixing nominal chemical composition of PR-30X13 powder, used as a testing material, with aluminum, which reacts with oxides on the surface of steel substrates, imparts strength to the bonding between the coating and the substrate, protects the base metal due to a combination of chemical components of the powder and creates a layer of dense surface coating. These dependencies are analyzed and parameters, exerting the greatest influence on their values, are identified. Taking into account the results obtained through numerical modeling, authors propose a mathematical model of a dependency between adhesion strength and certain values of surface roughness for different chemical compositions of flame spray powder. These studies will help in the development of certain material types for spraying and hardening of steel parts and products in order to improve their durability.

scholarly journals The effect of temperature on structural changes of NI55CO45 amorphous powder

2004 ◽  
Vol 36 (2) ◽  
pp. 105-112 ◽  
Author(s):  
M. Spasojevic ◽  
Aleksa Maricic ◽  
Lidija Rafailovic
Keyword(s):  
Current Density ◽  
Electrical Resistance ◽  
Structural Changes ◽  
Crystallization Process ◽  
Amorphous Powder ◽  
Solution Temperature ◽  
Specific Chemical ◽  
A Current ◽  
Shape And Size ◽  
Cobalt And Nickel

Cobalt and nickel alloy powders were obtained by electrochemical deposition on a titanium cathode from an ammonium solution of cobalt and nickel sulfate. Powders of a specific chemical structure and composition, particle shape and size were obtained by an appropriate choice of electrolysis parameters, current density, deposit growth rate and solution temperature and composition. Within the current density range of 5 - 450 mAcm-2, the current density did not significantly affect the chemical composition of the powders, but had a significant effect on the particle structure, shape and size. Crystal particles formed at a current density lower than 30 mAcm-2. Amorphous powders were obtained at a current density higher than 50 mAcm-2. Structural changes of the obtained amorphous powder of 55mol.% Ni, 45 mol.% Co, pressed under the pressure of 100 MPa, were investigated by measuring the temperature dependence of electrical resistance in isothermal and non-isothermal conditions varying from room temperature to 750?C. The process of thermal stabilization of defects that appeared during pressing occurred within the temperature range of 200-390?C. The DSC method was used to determine that the powder crystallization process occurred in two stages with peak temperatures of the exothermal maximum in the first and second stage of T1 = 438?C and T2 = 573?C, respectively. A distinct correlation between the change of electrical resistance and the crystallization process was established. The reduction of electrical resistively occurs during each crystallization stage.

scholarly journals Additive Manufacturing as a Means of Gas Sensor Development for Battery Health Monitoring

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 252
Author(s):  
Oleg Lupan ◽  
Helge Krüger ◽  
Leonard Siebert ◽  
Nicolai Ababii ◽  
Niklas Kohlmann ◽  
...  
Keyword(s):  
Structural Changes ◽  
Ethylene Carbonate ◽  
Size Control ◽  
Lithium Ion ◽  
Current Method ◽  
Direct Ink Writing ◽  
Physicochemical Processes ◽  
Heat Leakage ◽  
Annealing Step ◽  
A Current

Lithium-ion batteries (LIBs) still need continuous safety monitoring based on their intrinsic properties, as well as due to the increase in their sizes and device requirements. The main causes of fires and explosions in LIBs are heat leakage and the presence of highly inflammable components. Therefore, it is necessary to improve the safety of the batteries by preventing the generation of these gases and/or their early detection with sensors. The improvement of such safety sensors requires new approaches in their manufacturing. There is a growing role for research of nanostructured sensor’s durability in the field of ionizing radiation that also can induce structural changes in the LIB’s component materials, thus contributing to the elucidation of fundamental physicochemical processes; catalytic reactions or inhibitions of the chemical reactions on which the work of the sensors is based. A current method widely used in various fields, Direct Ink Writing (DIW), has been used to manufacture heterostructures of Al2O3/CuO and CuO:Fe2O3, followed by an additional ALD and thermal annealing step. The detection properties of these 3D-DIW printed heterostructures showed responses to 1,3-dioxolan (DOL), 1,2-dimethoxyethane (DME) vapors, as well as to typically used LIB electrolytes containing LiTFSI and LiNO3 salts in a mixture of DOL:DME, as well also to LiPF6 salts in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) at operating temperatures of 200 °C–350 °C with relatively high responses. The combination of the possibility to detect electrolyte vapors used in LIBs and size control by the 3D-DIW printing method makes these heterostructures extremely attractive in controlling the safety of batteries.

Effects of Cathode-Mandrel Surface Irregularities on the Mechanical Properties and Structure of Electroformed Iron Foil

1980 ◽  
Vol 22 (2) ◽  
pp. 49-54 ◽  
Author(s):  
W. A. Crichton ◽  
J. A. McGeough ◽  
J. R. Thomson
Keyword(s):  
Surface Roughness ◽  
Current Density ◽  
Cathode Surface ◽  
Foil Thickness ◽  
Iron Foil ◽  
Surface Irregularities ◽  
The Face ◽  
The Relationship ◽  
A Current ◽  
Cathodic Surface

Iron foil, of thicknesses between 003 and 0.15 mm has been electroformed at a current density of 30 A/dm2 and an electrolyte temperature of 100°C upon cathodes of surface roughness ranging from 0.04 to 4.4 μm Ra. The surface roughnesses of the face of the foil formed adjacent to the cathode, and of that electrode, are similar. The roughness of the reverse anodic face increases with increasing foil thickness, due to the increase in size of the crystal growth sites. The hardness of the cathodic face of the foil is unaffected by either cathode surface roughness or foil thickness. The hardness of the anodic face increases with both increasing cathode surface roughness and decreasing foil thickness, due to corresponding changes in grain size. A slight net decrease in tensile properties with increasing cathode surface roughness is attributed to the greater amount of stress concentration borne by the rougher foils. Young's modulus for the foil is not affected by cathode surface roughness. The electroforming of foil upon a mandrel surface carrying an isolated V-shaped scratch, 0.14 mm deep and 0.28 mm wide, has also been studied by numerical and experimental methods. The cathodic surface of foil is found to adopt the shape of the scratch whilst its upper side becomes level. The effect upon the geometric configuration of the foil depends upon the relationship between current efficiency and current density for the electrolyte, and on the polarisation (overpotential) characteristics at the mandrel surface.

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