Effect of Pb content on the surface topography and corrosion resistance of hot dip Zn-Al-Mg coatings

In this study,the effect of Pb content on the surface morphology and salt spray corrosion resistance of hot dip Zn-AI-Mg coatings was investigated. The results showed that the coating surface easily formed small grains of zinc spangle structures and that the salt spray con＇osion resistance of the coating decreased when Pb content was greater than 0.01%. The microstructure and energy dispersive spectrum analysis of surface and cross-sectional areas was performed by scanning electron microscopy. Pb content present in the coating was analyzed by glow discharge spectrum. The results showed that the distribution of Pb in the coating was not uniform. The Pb content was segregated on the surface and at the cross-section of the Zn-A1-MgZn2 ternary eutectic structure,especially,on the surface of the Zn-A1-MgZn2 ternary eutectic structure.

Effect of Mischmetal on Oxidation Resistance of 55Al－Zn Alloy Hot Dip Coating

The effect of mischmetal addition on high temperature oxidation resistance of 55wt% Al43.4 wt% Zn-1 .6wt% Si alloy hot-dip coatings has been investigated. It is found that rare earth addition improves high temperature oxidation resistance of the coatings. The oxidation tests at 800℃, 100 h and 1000℃, 50 h show that the coating with addition of 0. 1 % RE has the best properties. The morphology of oxide scale and element distribution of coating section were analysed by SEM, EPMA and XRD. It is indicated that mischmetal addition improves the adhesion between oxide scale and coating substrate, and spalling resistance of the scale is also improved with the addition of RE. Additionally, RE controls the degeneracy speed of Al-content in the coatings and inhibits the growth of Fe-Al intermetallic compound. For this reason, higher Al-content is kept in all the coatings with RE addition.

Eco-friendly polysaccharide coatings for antifouling and dragreduction and potential application for marine devices

Traditional antifouling agents usually have a certain toxic effect on marine environments and non-target organisms.In this study,Dictyophora indusiata polysaccharide(DIP)was applied as a natural antifouling surface modifier to prepare the surface coating for marine antifouling.Three DIP coatings were prepared:D.indusiata spore polysaccharide(DISP),D.indusiata volva polysaccharide(DIVP),and D.indusiata embryonic body polysaccharide(DIEP).The antifouling,tribological,and anticorrosion behavior of the coatings were examined.Results revealed that the three kinds of DIP coatings had excellent antifouling properties,which could effectively prevent the adhesion of Chlorella and the attachment of water-based and oily stains on the surface.Additionally,the coatings showed great mechanical stability and could maintain an extremely low coefficient of friction(COF<0.05)after continuous wear.The drag reduction rate of the coated surfaces reached 5%,showing a powerful lubrication performance.Furthermore,the DIP coatings presented an outstanding corrosion resistance,where the equivalent circuit impedances were 4-9 orders of magnitude higher than the control groups.This research showed a promising prospect of surface coating fabrication with DIP for marine devices to achieve the purpose of antifouling and drag reduction.

Manufacturing process and microstructure of copper-coated aluminum wires

Copper-coated aluminum wires exhibit good electrical conductivity, high thermal conductivity, low contact resistance of copper and low density, and provide economic advantages over aluminum. However, there are some problems in the manufacring processes of hot-dip copper-coated aluminum wires, such as the difficulties in controlling coating process. In this work, the hot-dip copper-coating method of aluminum wires was investigated for producing copper-coated aluminum wire composites. The interface microstructure between the aluminum wire and the copper coating layer was analyzed by scanning electron microscopy （SEM） and energy-dispersive X-ray spec- trometry （EDS）. Five different fluxing agents were tested. Experimental results show that appropriate conditions for the hot-dip process are determined as the liquid copper temperature of 1085℃ and the treatment time less than 1 s. A success in hot-dip copper-coated aluminum wires is achieved by hot-dipping a low-melting-point metal into a high-melting-point metal liquid, which is significant for the further devel- opment and application of copper-coated aluminum wire composites.

STUDY ON PREPARATION OF TUBULAR CERAMIC MICRO-FILTRATION MEMBRANE

A tubular micro filtration membrane was prepared with α alumina powder and ceramic tube support using dip coating method. The prepared membrane was characterized by SEM, mercury porosimetry and permeability measurement. The effects of the suspension properties and the preparation conditions on the structure and the membrane properties were discussed. The membrane was made with a top layer thickness of 50 μm , an average pore diameter of 0 45 μm , a porosity of 42% and a water flux of 6 5×10 -2 l/(m 2 h Pa). The membrane has a narrow pore distribution and good strength without crack forming, which can be used in industrial micro filtration process.

Optimising the corrosion performance of pre-painted steels

Pre-painted steel is one of the most important structural material of the 20th century well known for its excellent corrosion resistance and wide ranging applications.A typical pre-painted steel usually consists of a layer of metal coating system,preferably zinc or zinc alloy coating and a combination of layers of inorganic - organic coatings usually referred to as paint system.The corrosion resistance of the metal coating as well as the paint system may vary considerably based on their composition and the environment.For optimal corrosion performance of pre-painted steel,a judicious selection of both metal and inorganic-organic coating systems are essential.This paper reviews different types of possible corrosion issues in pre-painted steels and methods to optimise their performance.

Electroless Plating Lead and Lead-Tin on Copper Using an Eco-Friendly Plating Bath

Copper serpentines used in gas heaters are currently coated with lead-tin alloy using hot-dip technology where copper is immersed in molten lead (98%)-Tin at about 400&deg;C. The major drawback of this technique is the pollution resulted from lead vapors which cause much harm to the labors in the unit. The present work investigates an eco-friendly plating technique to replace the currently used technology. Electroless plating of copper samples with lead or Lead (98%)-Tin alloy is carried out from a plating bath contained lead salt, tin salt, reducing agent and stabilizing agent. The parameters affecting the coating quality such as the plating time, temperature and bath composition were optimized. The chemical analysis and coating morphology of the formed coatings are examined by XRD, SEM and EDS to reach the best bath composition as well as the best conditions to coat copper with lead or lead-tin electrolessly. The electrochemical properties of copper and copper coated samples are also examined using electrochemical impedance spectroscopy.

Gamma(ɣ)‑MnO_(2)/rGO Fibered Cathode Fabrication from Wet Spinning and Dip Coating Techniques for Cable‑Shaped Zn‑Ion Batteries

Cable/fber-shaped Zn-ion batteries are designed to power wearable electronics that require high fexibility to operate on human body.However,one of technical challenges of these devices is the complexity and high cost for manufacturing fbered cathode.In this work,we demonstrated gamma manganese oxide(ɣ-MnO_(2))/reduced graphene oxide(rGO)fbered cathode fabrication using facile and cost-efective fber production and active material coating techniques.Specifcally,rGO fbers were fabricated via wet spinning,followed by chemical reduction with hydroiodic acid(HI).The synthesized rGO fber bundle was then dip-coated with a mixture ofɣ-MnO_(2),carbon black or multi-walled carbon nanotubes,and xanthan gum or polyvinylidene fuoride binder to obtainɣ-MnO_(2)/rGO fbered cathode.We studied the efect of binders and conductive materials on physical properties and electrochemical performance of the fbered cathode.It was found that hydrophobic binder had more benefts than hydrophilic binder by providing higher active material loading,better coating layer homogeneity,and more stable electrochemical performance.Cable-shaped Zn-ion batteries(CSZIBs)were then assembled by using theɣ-MnO_(2)/rGO fbered cathode,Zn wire anode,and xanthan gum polymeric gel electrolyte with 2 M ZnSO_(4) and 0.2 M MnSO_(4) salts without a separator.We investigated the battery assembling procedure on a glass slide(prototype ZIB)and in a plastic tube(cable-shaped ZIB),and evaluated their electrochemical performance.The CSZIB showed promising maximum capacity of~230 mAh/g with moderate cycling stability(80%capacity retention after 200 cycles)and high fexibility by maintaining the potential after consecutive pressing for 200 times under controlled pressing distance,duration,and testing speed.Finally,we explored ion intercalation behaviours and proposed a H^(+)/Zn^(2+)co-intercalation mechanism in ZIB withɣ-MnO_(2) active material.

SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

The SnS thin films were synthesized by chemical bath deposition （CBD）, dip coating and successive ionic layer adsorption and reaction （SILAR） techniques. In them, the CBD thin films were deposited at two tem- peratures： ambient and 70℃. The energy dispersive analysis of X-rays （EDAX）, X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscopy （SEM） and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I-V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

Lubrication theory for free-surface flows with finite slopes and fluxes

It is known that free-surface flows with small slopes can be described by classical lubrication theory.By replacing the assumption of quasi-parallel flows with local wedge flows,the classical lubrication theory has been generalized to the situation with finite surface slopes and vanishing fluxes,e.g.,steady capillary flows with moving contact lines.In this work,this theory is further extended by imposing the contribution of finite fluxes,which can be modeled by a source/sink flow in a wedge.The resulting lubrication equation is used to investigate the surface morphologies observed in dip coating of an inclined plate,including the Landau-Levich-Derjaguin film,dimple and capillary shock.Dependence of these structures on the inclination angle and relative speed with respect to the plate is discussed in detail.Numerical solutions of the lubrication equation agree well with available asymptotic theory.