Smooth Coatings Research Articles

Traditional Chinese Veterinary Medicine to Treat Intervertebral Disc Disease in a Dachshund

An 8-year-old, male, smooth coat Dachshund presented with bilateral hindlimb paralysis (Grade IV) and pain in the lumbar area. He was diagnosed with intervertebral disc disease (IVDD) and the traditional Chinese veterinary medicine (TCVM) Pattern diagnosis was Spinal Cord Qi/Blood Stagnation with Kidney Qi Deficiency. The goal for treating IVDD patients is to eliminate spinal cord compression and resolve inflammation in order to alleviate the animal’s pain and restore normal mobility. The medical approach to the present case was to use the TCVM treatment modalities of acupuncture, Chinese herbal medicine (modified Da Huo Luo Dan/Double P II) and Tui-na massage to address the TCVM Patterns diagnosed. TCVM treatment sessions were initiated at a frequency of twice a week for 2 weeks, followed by once weekly sessions for 2 more weeks and a final session 1 month later along with oral daily administration of Double P II. The combination of TCVM treatment modalities resulted in a successful clinical outcome with the dog walking after 6 treatment sessions over a 4-week period. This case illustrates that TCVM, including acupuncture, Tui-na massage and Chinese herbal medicine, can be effective as a sole therapy for thoracolumbar IVDD, or part of integrated therapy with conventional medicine.

A Path to Significant Reduction of the Interfacial Contact Resistance of Sintered Titanium Porous Transport Layers in Advanced Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) are a leading industry solution to large scale production of green hydrogen, and as a form of energy storage [5]. The PEMWEs have the advantages of having greater energy efficiency, higher product purity, and are environmentally friendly. Within the construction of a PEMWE stack, there are many catalysts coated membranes (CCMs) sandwiched between anode porous transport layers (PTLs) and cathode Gas Diffusion Layers. The PTL is constructed of sintered titanium powder or fibers. The Ti-PTL is on the anode side of a PEMWE cell where the water diffuses towards the CCM. The anode half-cell reaction or oxygen evolution reaction (OER) occurs on this side of the cell. This is important as the PTL is in contact with the bipolar plate (BPP) and the anode catalyst layer [9].A key aspect plaguing the PEMWEs is the highly oxidative and corrosive environment that is typically observed on the anode side. This significantly affects the interfacial contact resistance (ICR) of the components as the corrosion can cause the ohmic resistance of the PTL to increase. In order to combat the corrosion in the PTLs, in this work we use two thin film deposition methods, Physical Vapor Deposition (PVD) and Vacuum Sputtering, to deposit protective metal layers on top of the state-of-the-art Ti PTLs [2]. The explored metal coatings of interest are Platinum (Pt) and Gold (Au) [9]. For the purposes of these experiments, Au and Pt coatings with various thicknesses are deposited on Ti-PTLs by using either PVD or vacuum spattering method. As deposited thin films are characterized by scanning electron microscopy (SEM), digital optical microscopy, and inductively coupled plasma (ICP) analysis. Also, the in-plane conductivity and the ICR of all samples of interest are measured before and after the electrochemical tests by using the 4-probe method and in-house build setup for ICR measurements. The optimal deposition parameters for fabrication of thin, continuous and smooth Pt and Au protective coatings that result in minimum ICR and improved in-plane conductivity of the PTLs of interest are identified, and the results will be reported at the ECS 241 meeting.

Microwave-assisted titanium nitride coating processing using nitride powders in ambient atmosphere

The microwave-assisted titanium nitride (TiN) coating method using TiN powders as a raw material was investigated for hard and smooth TiN coatings by decreasing the energy of the exothermic reaction between the raw powder and air. A titanium-aluminum-vanadium alloy (Ti-6Al-4 V) substrate was buried in TiN powders and irradiated with 2.45 GHz microwaves using a multimode cavity. After microwave processing, TiN films were found to be successfully deposited on the Ti-6Al-4 V substrate without atmospheric control. X-ray diffraction results indicated that face-centered cubic (fcc)-TiN phase increased with increasing temperature. TiN coating films synthesized at 900 °C and 800 °C were smoother than those at 1000 °C. Besides, the TiN films synthesized at 900 °C exhibited 697 HV with arithmetic mean roughness (Ra) = 0.29. These results demonstrated that a hard and smooth TiN film can be obtained using TiN powders as raw materials.

Gastric Duplication in a Preterm Neonate

Background: Gastrointestinal (GI) duplication is defined as a spherical structure with a muscular coat and is lined by a mucous membrane. It is a rare congenital anomaly. Clinical Description: A preterm baby born, delivered at 31 weeks, was diagnosed with respiratory distress syndrome and managed as per hospital protocol. While being weaned off from nasal continuous positive airway pressure, feeding was started. He developed vomiting and epigastric distension within 6 h. Management: The baby was investigated for the cause, and an early-onset sepsis was excluded. X-ray abdomen showed distended stomach and gas shadows in the bowel loops. Ultrasound did not reveal any gastric outlet obstruction, but significant gaseous distension of the stomach prompted us to make a dye study of the upper GI tract, which revealed cystic outpouching of the stomach that communicated with the gastric lumen. Similar findings were seen on computed tomographic scanning. Exploratory laparotomy performed revealed a large cyst communicating with the stomach at the lesser curvature. This was dissected out entirely from the margin of the stomach. Histopathology revealed highly congested cyst wall with an inner lining of gastric epithelium and gastric glands and an outer smooth muscle coat, confirming a gastric duplication cyst. Conclusion: Gastric duplication should be considered as a differential in newborns with feed intolerance, epigastric distension, and significant distension of the stomach. Although serial radiological investigations provide supportive evidence for this condition, the diagnostic confirmation is obtained by gross inspection and histopathology. In view of high risk of malignant transformation, surgical resection of the entire cyst remains the most definitive management.

Rational Design of Durable Anti-fouling Coatings with High Transparency, Hardness, and Flexibility.

Highly transparent, durable, flexible and smooth coatings with excellent anti-fouling properties have broad applications on cars, windows, and touch screens. However, the coexistence of these multi-functions is difficult to achieve in a single coating material. Here, a coating is developed with excellent performance of high transparency (98.8%), anti-fouling, high hardness (8H), and flexibility simultaneously (TAHF coating). In the material design, methyl etherified melamine formaldehyde resin, hexamethylene diisocyanate trimer, and mono-aminopropyl terminated polydimethylsiloxane (NH2-PDMS) were used as a polymer matrix to provide surface hardness, a cross-linker was used to provide toughness, and omniphobic groups from NH2-PDMS were used to provide anti-fouling performance. The TAHF coating has excellent liquid repellence even after six months of outdoor exposure, 260 h of UV light exposure, and 1500 wear and 2000 bending cycles, and its chemical shielding performance is superior to that of a commercial anti-corrosive coating. This strategy would provide a new route for the design of multifunctional anti-fouling coatings for practical applications.

Bioinspired microgroove arrays with drag reduction and hydrophobic properties

Reducing energy consumption is one of the most effective ways to solve the problem of energy shortage. In this work, nature-inspired paint microgroove arrays with different periods were fabricated using a one-step laser ablation method. A wind tunnel experiment was performed at two wind speeds, 27.7 and 33.3 m/s, to collect drag force data on smooth and structured paint coatings. The results showed that microgroove arrays oriented perpendicular to the flow direction were beneficial to drag reduction, and a drag reduction rate of up to 7.2% was obtained. Meanwhile, the microgroove arrays induced by laser ablation changed the wettability of the paint surface to hydrophobicity. The contact angle shows a slightly decreasing trend with an increase in the periodic scale. Furthermore, the anticorrosion properties of these microgrooves make them advantageous in harsh environments. The fabricated drag-reducing paint microstructures, with the features of self-cleaning and durability, have the potential to be applied on vehicles to realize speed improvement and energy saving.

Optimum Selection of Coated Piston Rings and Thrust Bearings in Mixed Lubrication for Different Lubricants Using Machine Learning

The purpose of this study is to build a parametric algorithm combining analytical results and Machine Learning in order to improve the tribological performance of coated piston rings and thrust bearings in mixed lubrication using different synthetic lubricants. The friction models for piston ring conjunction and pivoted pad thrust bearing consider the basic lubrication theory, the detailed contact geometry and the complete lubricant action for a wide range of speeds. The data produced from the analytical solutions are used as input for the training of regression models. The effect of TiN, TiAlN, CrN and DLC coatings on friction coefficient are investigated through multi-variable quadratic regression and support vector machine models. The optimum selection is considered when the minimum friction coefficient is predicted. Smooth TiN2 and TiAlN coatings seem to affect better the ring friction coefficient than rougher steel, TiN1 and CrN coatings using an uncoated or coated Nickel Nanocomposite (NNC) cylinder. Using an NNC cylinder for better durability, the friction coefficients were found to be higher by 31.3−58.8% for all the studied rings due to the rougher surface morphology. On the other hand, the results indicate that pads coated with DLC show lower friction coefficients compared to the common steel and TiAlN, CrN, and TiN applications. The multi-variable second-order polynomial regression models were demonstrated to be 1−6% more accurate than the quadratic support vector machine models in both tribological contacts.

Investigation of a high-frequency magnetron sputtering system operation modes during copper thin films deposition

The results of studying the radio frequency (RF) magnetron sputtering (MS) operation parameters during copper sputtering are presented. A comparison of the growth rate dependence on power during the operation of MS is made in RF and DC modes. The pressure dependences of the RFMS growth rate and bias target voltage are obtained. The prospect of using RFMS for deposition of smooth coatings is shown.

Plasma deposited high surface area‐activated carbon coatings: Theory combining particle generation, aggregation and deposition explains microstructure

AbstractHigh surface area carbon coatings are produced by plasma‐enhanced chemical vapour deposition using a high‐voltage dielectric barrier discharge under conditions where aggregates are formed in the plasma and the growing coating is subjected to plasma immersion ion implantation. We extend the Smoluchowski aggregation theory to include the continuous production of monomers to explain the observed microstructure of the coatings as a function of the pressure of deposition. The larger particles show evidence of the accretion of monomers on their surfaces with characteristic voids resulting from island growth. The coatings are subjected to plasma immersion ion implantation using high‐voltage pulses that create radicals for binding biomolecules. The increased surface area by the presence of the aggregated particles binds a significantly higher amount of protein than smooth coatings, making them potentially useful for electrodes, biosensing and drug delivery.

Si-HfO2 composite powders fabricated by freeze drying for bond layer of environmental barrier coatings

Hafnia-doping is expected to improve the performance of silicon bond layer of EBC system for SiC-based CMC. However, obtaining a compositional uniform Si-HfO2 composite coating is still a challenge due to the big difference of their melting point, density and fluidity of powders. Fabrication of evenly distributed Si-HfO2 composite powders with good fluidity and activity is a promising strategy. Freeze drying, a cost-effective and green method, was applied to make Si-HfO2 composite powders for the first time. Highly active nano-sized Si and HfO2 powders were mixed uniformly into a slurry, which was frozen and dried into solid lamellar structure. After crushing down and sieving, composite powders with controllable particle size and good fluidity were achieved, which inherited the uniformity of the slurry. Thickness of the lamellar structure determines the size and shape of the final composite powders, which can be controlled by simply varying the freezing temperatures. Compact and smooth bond coatings with evenly distributed Si and HfO2 were successfully fabricated from these composite powders by plasma spraying. We hope this work could excite the whole society to focus more on the structural design of powders and coatings as well as material selection to further boost the performance of EBCs.

Titanium carbide coating to improve surface characteristic, wear and corrosion resistance of spheroidal graphite cast irons

In this study, titanium carbide (TiC) coatings were grown on the surface of a spheroidal graphite cast iron (SGI) via thermo-reactive diffusion (TRD) using powder-pack processing at 800 °C, 850 °C and 900 °C for 4 h. The TiC coatings obtained on the SGI were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), surface profilometry, microhardness, VDI adhesion testing, wear testing, and electrochemical corrosion testing. Depending on the TRD temperature, continuous, crack-free, and smooth TiC coatings of 5–11 μm thickness and 27.96–32.45 GPa hardness were obtained on the surface. The high chemical stability, high hardness, and good adhesion strength of TiC coatings resulted in a reduced friction, high wear resistance, and superior corrosion resistance compared to the untreated sample. Delamination and oxidation assisted abrasive wear transformed into oxidation-assisted adhesive wear in the coated samples. Galvanic corrosion was dominant in untreated SGI, while homogeneous corrosion occurred in the coated samples. TiC coatings grown using TRD have the potential to be used in engineering components exposed to tribo-corrosive conditions.

Highly Conductive and Visibly Transparent p-Type CuCrO2 Films by Ultrasonic Spray Pyrolysis.

The development of high-performing p-type transparent conducting oxides will enable immense progress in the fabrication of optoelectronic devices including invisible electronics and all-oxide power electronics. While n-type transparent electrodes have already reached widespread industrial production, the lack of p-type counterparts with comparable transparency and conductivity has created a bottleneck for the development of next-generation optoelectronic devices. In this work, we present the fabrication of delafossite copper chromium oxide p-type transparent electrodes with outstanding optical and electrical properties. These layers were deposited using ultrasonic spray pyrolysis, a wet chemical method that is fast, simple, and scalable. Through careful screening of the deposition conditions, highly crystalline, dense, and smooth CuCrO2 coatings were obtained. A detailed investigation of the role played by the deposition temperature and the cation ratio enabled the properties of the prepared layers to be reliably tuned, as verified using X-ray diffraction, X-ray photoelectron spectroscopy, optical spectroscopy, Hall effect measurements, and electron and atomic force microscopies. We demonstrate record conductivities for solution-processed CuCrO2, exceeding 100 S cm-1, and we also obtained the highest value for two separate figures of merit for p-type transparent conducting oxides. These performances position solution-deposited CuCrO2 as the leading p-type transparent-conducting oxide currently available.

Structural, Mechanical and Electrical Characteristics of Copper Coatings Obtained by Various Electrodeposition Processes

Mechanical (hardness and adhesion) and electrical (sheet resistance) characteristics of electrolytically produced copper coatings have been investigated. Morphologies of Cu coatings produced galvanostatically at two current densities from the basic sulfate electrolyte and from an electrolyte containing levelling/brightening additives without and with application of ultrasound for the electrolyte stirring were characterized by SEM and AFM techniques. Mechanical characteristics were examined by Vickers microindentation using the Chen–Gao (C–G) composite hardness model, while electrical characteristics were examined by the four-point probe method. Application of ultrasound achieved benefits on both hardness and adhesion of the Cu coatings, thereby the use of both the larger current density and additive-free electrolyte improved these mechanical characteristics. The hardness of Cu coatings calculated according to the C–G model was in the 1.1844–1.2303 GPa range for fine-grained Cu coatings obtained from the sulfate electrolyte and in the 0.8572–1.1507 GPa range for smooth Cu coatings obtained from the electrolyte with additives. Analysis of the electrical characteristics of Cu coatings after an aging period of 4 years showed differences in the sheet resistance between the top and the bottom sides of the coating, which is attributed to the formation of a thin oxide layer on the coating surface area.

Control of zeta potential of polymer layers on selective ion exchange membranes for electrodialysis

The formation of compositions from polymer layers can significantly increase the monovalent selectivity of ion-conducting materials used in membrane separation processes. It is known that the achieved selectivity strongly correlates with the charge of the upper polymer layer determined through its zeta potential. It is of interest to confirm the strict dependence of the zeta potential on the charge of the upper polymer layer for rough commercial membranes. In this work, we studied the zeta potentials of polyallylamine and sodium polystyrene sulfonate adsorbed on heterogeneous membrane in solutions with different charge numbers of the counterion. It is shown that such coatings are characterized by more negative values of zeta potentials in comparison with those known for smooth coatings and that, upon transition to doubly charged counterions, there is no surface recharge.

Application of Epoxy Coatings to Increase the Efficiency of Wax Oils Production

When producing hydrocarbons, an important task relates to the optimization of the stock of the producing well. The main complications for wells in non-working mode are represented by the formation of asphalt-resin-paraffin deposits. This issue is one of the most common problems in the production and transportation of oil. A promising method to deal with these deposits is the application of smooth coatings made of epoxy polymers on the inner surface of the production well tubing. In this work, a number of laboratory studies were carried out on the “Cold Finger” installation to assess the effectiveness of this approach. These laboratory studies have shown that the efficiency related to smooth coatings is 27% while the resulting thermal conductivity ranges from 0.259 to 0.279 W/(m°C). These results demonstrate that this technology can reduce the amount of organic deposits and increase the temperature of oil.

Implementation of the Chicot–Lesage Composite Hardness Model in a Determination of Absolute Hardness of Copper Coatings Obtained by the Electrodeposition Processes

The influence of various electrolysis parameters, such as the type of cathode, composition of the electrolyte and electrolysis time, on the morphology, structure and hardness of copper coatings has been investigated. Morphology and structure of the coatings were analyzed by scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray diffraction (XRD), while coating hardness was examined by Vickers microindentation test applying the Chicot–Lesage (C–L) composite hardness model. Depending on the conditions of electrolysis, two types of Cu coatings were obtained: fine-grained mat coatings with a strong (220) preferred orientation from the sulfate electrolyte and smooth mirror bright coatings with a strong (200) preferred orientation from the electrolyte with added leveling/brightening additives. The mat coatings showed larger both measured composite and calculated coating hardness than the mirror bright coatings, that can be explained by the phenomena on boundary among grains. Independent of electrolysis conditions, the critical relative indentation depth (RID) of 0.14 was established for all types of the Cu coatings, separating the zone in which the composite hardness can be equaled with the coating hardness and the zone requiring an application of the C–L model for a determination of the absolute hardness of the Cu coatings.

Morphologies and textures of rhenium coatings electrodeposited in chloride molten salts

Rhenium (Re), with excellent comprehensive high-temperature properties, is an ideal high-temperature coating material. Electrodeposition technology has attracted much attention in recent years due to its relatively low fabrication cost and superior mechanical properties of Re. In this work, the morphologies and textures of Re coatings electrodeposited in NaCl-KCl-CsCl ternary melts were systematically studied at 20–250 mA/cm2 in the temperature ranging from 700 to 880 °C. With increasing polarization (i.e., increasing current density or decreasing temperature), the growth mechanism of the ED Re coating changes from lateral growth with preferred growth crystal plane of (002) to outward growth with preferred growth crystal plane of (110). The morphologies of the Re coatings change in the order of faceted grains, pyramid-like surface, spired starfish-like surface, intertwined roots-like surface and dendritic powder. The optimal deposition process range for dense and smooth Re coatings is as follows: the temperature 800–850 °C and current density 50–100 mA/cm2. The average microhardness of the Re coatings deposited at 50 mA/cm2 in the temperature range of 800–850 °C was ~377 kg/mm2.

Phenotypical characterization of Kababich breed in peri-urban zone of N’Djamena-Chad

This work was carried out on the phenotypic characteristics of the Kababich sheep exploited in the peri-urban zone of N'Djamena (Chad). This phenotypic characterization of Kababich sheep should be continued on local breeds for genetic improvement and objective optimization of productivity. The objective of this study is the characterization of phenotypically Kababich sheep exploited in the peri-urban area of ​​N'Djamena-Chad. It was conducted in 39 farms and involved 1035 sheep aged less than one year old. Phenotypic traits were measured according to the guideline defined by FAO. A total of 12 variables were measured including five qualitative and seven quantitative. The results obtained show a positively significant correlation (p> 0.001) between the age of the sheep estimated by the breeder and the dentition (0.83). The ears are drooping and measure 17.90 ± 2.77 cm. The color of the brown dress (fawn) and the smooth and short coat are dominant. The females are matte and the rams of brown dress have horns in the forms of the vestiges. The Kababich is large with a height at the withers of 81.50 ± 9.40 cm, a rump height of 83.24 ± 9.42 cm and a chest circumference of 88.29 ± 9.22 cm. The body is 72.82 ± 9.63 cm long, has a basin width of 19.89 ± 2.53 cm and a chest depth of 40.68 ± 5.16 cm. These measurements show that Kababich is a meat breed by excellence. In addition, the sexual dimorphism very accentuated in this race orients towards a valorization of the young males in the fattening workshops.

Mirror-like Bright Al-Mn Coatings Electrodeposition from 1-Ethyl-3 Methylimidazolium Chloride-AlCl3-MnCl2 Ionic Liquids with Pyridine Derivatives.

The effects of three pyridine derivative additives, 4-hydroxypyridine, 4-picolinic acid, and 4-cyanopyridine, on Al-Mn coatings were investigated in 1-ethyl-3-methylimidazolium chloride-AlCl3-MnCl2 (EMIC-AlCl3-MnCl2) ionic liquids. The smooth mirror-like bright Al-Mn coatings were obtained only in the EMIC-AlCl3-MnCl2 ionic liquids containing 4-cyanopyridine, while the matte Al-Mn coatings were electrodeposited from EMIC-AlCl3-MnCl2 without additives or containing either 4-hydroxypyridine or 4-picolinic acid. The scanning electron microscope and X-ray diffraction showed that the bright Al-Mn coatings consisted of nanocrystals and had a strong (200) preferential orientation, while the particle size of matte Al-Mn coatings were within the micron range. The brightening mechanism of 4-cyanopyridine is due to it being adsorbed onto the cathode to produce the combined effect of (1) generating an overpotential to promote Al-Mn nucleation; (2) inhibiting the growth of the deposited nuclei and enabling them grow preferentially, making the coating composed of nanocrystals and with a smooth surface. The brightening effect of 4-cyanopyridine on the Al-Mn coatings was far better than that of the 4-hydroxypyridine and the 4-picolinic acid. In addition, the bright Al-Mn coating was prepared in a bath with 6 mmol·L−1 4-cyanopyridine and displayed superior corrosion resistance relative to the matte coatings, which could be attributed to its unique nanocrystalline structure that increased the number of grain boundaries and accelerated the formation of the protective layer of the corrosion products.

Encapsulation of interdigitated electrodes by PTFE coatings via closed batch initiated chemical vapor deposition

Encapsulation of sensor electrodes is critical for stability and optimum performance of the device. Encapsulation method to be employed should be compatible with the device architecture, provide conformal coatings and be cost effective. In this study, closed batch initiated chemical vapor deposition (CB-iCVD) method is used to deposit Polytetrafluoroethylene (PTFE) encapsulation layers on interdigitated electrodes (IDE). The CB-iCVD method enables deposition of conformal, ultra thin PTFE coatings on patterned surfaces with high precursor consumption efficiencies. The electron microscopy analysis confirms the conformality of the smooth coatings on the IDEs. The encapsulation performance of the coatings in the presence of standard pH solution is demonstrated by the frequency dependent electrochemical impedance spectroscopy (EIS) analysis, which confirms that the PTFE layer can successfully isolate the electrodes from the reactive environment.