Physical Alloying of Plasma Metallization Carbide Nanocomposite Coating by Allotropic Carbon Nanostructures

The fundamental scientific problem for micro- and nano-electronics has been solved—methods for creating and investigating properties of physically doped materials with spatially inhomogeneous structure at the micro- and nano-meter scale have been developed. For the application of functional nanocomposite film coatings based on carbides of various transition metals structured by nanocarbon, for the first time in the world, we developed a new technique for their plasma deposition on a substrate without the use of reaction gases (hydrocarbons such as propane, acetylene, etc.). We have created nanostructured film materials, including those with increased strength and wear resistance, heterogeneous at the nanoscale, physically doped with nanostructures—quantum traps for free electrons. We learned how to simultaneously spray (in a plasma of a stationary magnetron discharge) carbides and graphite from a special mosaic target (carbide + carbon) made mechanically. As a result of such stationary sputtering of carbides and carbon, plasma nanostructured coatings were obtained from nanocarbides, metal nanocrystals and nanocarbon. Our design of such a target made it possible to intensively cool it in the magnetron body and spray its parts (carbide + carbon) simultaneously with a high power density of a constant plasma discharge—in the range of values from 40 W/cm2 to 125 W/cm2. Such sputtering with a change in the power or the initial relative surface areas of various parts of the mosaic target (carbon and carbide) made it possible to change the average density of carbide, metal and carbon in a nanostructured (nanocarbon and metal nanostructures) coating. The changed relative density of various components of the nanocomposite (nanostructures of carbide, metal, and carbon in the form of graphite) significantly affected the physical properties of the nanocomposite coating. The creating method of multiphase nanostructured composite coatings (based on carbides of transition metals) with high hardness of 30 GPa, a low coefficient of friction to dry 0.13 - 0.16, with high heat resistance up to 3000°C and thermal stability in the nanocrystalline state over 1200°C is developed. It is established that the presence of nanographite in the composite significantly improves the impact strength and extends the range of possible applications, compared with pure carbides. The solution to this problem will allow creating new nanostructured materials, investigating their various physical parameters with high accuracy, designing, manufacturing and operating devices with new technical and functional capabilities, including for the nuclear industry and rocket science.

Uniform nanoplating of metallic magnesium film on titanium dioxide nanotubes as a skeleton for reversible Na metal anode

To meet the low-cost concept advocated by the sodium metal anode,this paper reports the use of a pulsed electrodeposition technology with ionic liquids as electrolytes to achieve uniform nanoplating of metallic magnesium films at around 20 nm on spaced titanium dioxide(TiO_(2))nanotubes(STNA-Mg).First,the sodiophilic magnesium metal coating can effectively reduce the nucleation overpotential of sodium metal.Moreover,three-dimensional STNA can limit the volume expansion during sodium metal plating and stripping to achieve the ultrastable deposition and stripping of sodium metals with a high Coulombic efficiency of up to 99.5%and a small voltage polarization of 5 mV in symmetric Na||Na batteries.In addition,the comparative study of sodium metal deposition behavior of STNA-Mg and STNA-Cu prepared by the same route further confirmed the advantage of magnesium metal to guide sodium metal growth.Finally,the prepared STNA-Mg-Na metal anode and commercial sodium vanadium phosphate cathode were assembled into a full cell,delivering a discharge capacity of 110.2 mAh·g^(-1)with a retention rate of 95.6%after 110 cycles at 1C rate.

Microstructures and properties of Fe-Co-B-Si-Nb coating prepared by laser cladding and remelting

High power laser cladding of [ （ Fe0. 5 Co0. 5 ） 0. 75 B0. 2 Si0.05 ] 95. 7 Nb4. 3 powder mixture afier-remelting was performed to fabricate Fe-based metallic glass coating on the surface of steel of China Classification Society： Grade B （CCS-B）. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） with energy dispersive spectrometer （EDS）, Vickers hardness tester and corrosion resistance tester were employed to characterize microstructures and evaluate properties of this coating. According to the results of SEM, XRD and TEM, the cladding coating consisted of nanocrystalline embedded in amorphous phase. EDS data indicated that Nb segregated in the amorphous matrix. The results of hardness test revealed that the hardness of the top layer was higher than that of the inner layer of the coating. The coating exhibited excellent corrosion resistance in a 3.5% NaCl solution.

Effect of Salt Spray Corrosion on Tribological Properties of HVOF Sprayed NiCr-Cr3C2 Coating with Intermediate Layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr3C2 coating with intermediate layer. Ni-Zn-Al2O3 coatings as interlayers were prepared by low pressure cold spray（LPCS） between NiCr-Cr3C2 cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.

Reactive synthesis Ti （CN） -based metal ceramic coating by electric-spark deposition

Electric-spark deposition （ESD） was adopted for depositing a Ti（ CN） -based ceramic coating on the TC4 titanium alloy substrate using a laboratory-developed electric-spark deposition system, a nitrogen-sealed atmosphere and graphite electrode. The surface morphology, microstructure, interfacial behavior between the coatings and substrate, phase and element composition of the coatings were investigated by scanning electron microscope （ SEM ） , X-ray diffraction （ XRD ） , X-ray photoelectron spectroscopy （ XPS ） and Auger electron spectroscopy （ AES ） . Microhardness profile was measured with a Vickers microhardness tester. The results show that metallurgical bond between the coating and substrate is realized and the phase of coatings are made up of Ti（ CN ） spherocrystal and dendritic crystal, TiV and C. Ti（ CN） ceramic particles, which is in-situ synthesized by the reaction among titanium from the substrate, carbon from the graphite electrode and nitrogen from the shielding nitrogen gas, is about 600 mn and distributes dispersively among the coatings. Microharduess profile falls off with the coatings thickness increasing and the highest microhardness values of the superficial coating could be up to 1 496HV, which is six times more than that of the substrate.

Influence of oxidant KMnO_4 on film-forming process of rare earth metal conversion coating on LY12 aluminum alloy

A Cu/Al galvanic couple was established to study the influence of the oxidantKMnO_4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminumalloy. It is found that the galvanic couple simulative experiment accords with the actual immersion,and it can be substantially used to simulate the behavior of LY12 aluminum alloy in thefilm-forming process. It is showed that the formation of the coating is quickened in CeCl_3 solutioncontaining KMnO_4 compared with that not containing KMnO_4. XPS results reveal that the coatingformed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation ofREM conversion coating changes when KMnO4 is added.

Ceramics Surface Modification by Excimer Laser Metal Coating

Thin metallic layers (~ 2 μm) of Ni were deposited on polycrystalline Al2O3. ZrO2 and (Ce-TZP)+Al2O3 ceramic substrates. and further irradiated with pulsed excimer (Xeno chloride) laser pulses. The laser energy density was varied from 0.21 to 0.81 J / cm2 to optimize bending strength. For ZrO2 ceramic, it was found that the strength increases from 530 to 753 MPa at 0.51 J / cm2 irradiation. For Al2O3 and (Ce-TZP)+ Al2O3 the fracture strength also increases in varying degree. The causes of strength increment were discussed.

AN EXPERIMENTAL STUDY OF CO_2 LASER CUTTING OF METALLIC COATED SHEET STEELS

An experimental investigation is outlined for the CO 2 laser cutting process of metallic coated sheet steels, GALVABOND. It shows that by proper control of the cutting parameters, good quality cuts are possible at high cutting rate. Visual examination indicates that when increasing the cutting rate to as high as 5000 mm/min (about 100 times that suggested previously), kerfs of better quality can be achieved. Some kerf characteristics such as the width, heat affected zone and dross in terms of the process parameters are also discussed. A statistical analysis has arrived at a recommendatio on the optimum cutting parameters forprocessing GALVABOND.

Effect of rare earth Eu on anti-passivation of metal oxide anode coating

The anti passivation effect of metal oxide anode coating doped with rare earth element Eu was discussed. The morphology and the composition distribution of the metal oxide coating anode before and after electrolysis were studied by SEM and EDX analyses. The results show that the erosion of the electrolyte at the defects is the main cause for the failure of the coating. The erosion rate of the electrolyte is anisotropic. In area with high density of defects, the erosion rate is very fast and the failure of the coating is very quick. Moreover, the life time of the coating is prolonged by the doping of Eu. [

MEASUREMENT OF INTERNAL STRESSES OF METAL MULTILAYER COMPOSITE COATINGS

The principle, formula and determination of internal stresses of metal multilayer composite coatings by means of the bending strip method were studied. Using this method, internal stresses of ion-plated metal multilayer composite coatings and thick monolayer coating of aluminium bronze, stainless steel and nickel-iron alloy were determined. The reason of decrement in internal stresses of multilayer composite coatings was discussed.

On the Regression-Tensor Analysis of the Hardening Process of Metal Coatings

This paper constructs and studies a nonlinear multivariate regression-tensor model for substantiation of necessary/sufficient conditions of optimization of technological calculation of multifactor physical and chemical process of hardening of complex composite media for metal coatings. An adaptive a posteriori procedure for parametric formation of the target quality functional of integrative physical and mechanical properties of the designed metal coating has been proposed. The results of the research may serve as elements of a mathematical language when creating automated design of precision nanotechnologies for surface hardening of complex composite metal coatings on the basis of complex tribological and anticorrosive tests.

Preparation and Characterization of Poly(melamine-urea-formaldehyde) Tetradecanol Microcapsules Coated with Silver Particles

A novel type of microencapsulated phase change materials(microPCMs)based on 1-tetradecanol(TD)core and silver-coated poly(melamine-urea-formaldehyde)(MUF)shell was successfully synthesized by in situ polymerization method followed by silver reduction.Fourier-transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),scanning electron microscopy with energy dispersive X-ray spectrometry(SEM/EDS),thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)were used to characterize the chemical structure,morphology and thermal properties of the as-prepared silver-coated microPCMs.FTIR analysis confirmed the successful encapsulation of TD with MUF wall materials.The SEM and EDS results indicated that the prepared silver-coated MUF microPCMs exhibited uniform spherical shape with a perfect silver outer layer.From XRD analysis,the Ag metal dispersed on the surface of microcapsules presented the form of elementary substance.The deposition weight of silver particles on the microcapsule surface increased with increasing the amount of silver nitrate,as indicated by EDS tests.The DSC results indicated that the melting temperature and the melting latent heat of microPCMs modified with 0.7g of silver nitrate in 150mL aqueous solution were 39.2°C and 126.6J·g^-1,respectively.Supercooling of the microPCMs coated with silver particles was effectively suppressed,compared with that of microPCMs without Ag.Thus,the encapsulation of TD with silver-coated MUF shell developed by this work can be an effective method to prepare the microPCMs with enhanced thermal transfer performance and phase change properties.

Fabrication and Thermal Conductivity Improvement of Novel Composite Adsorbents adding with Nanoparticles

Thermal conductivity is one of key parameters of adsorbents, which will affect the overall system performance of adsorption chiller. To improve adsorbent＇s thermal conductivity is always one of research focuses in chemisorption field. A new chemical composite adsorbent is fabricated by adding carbon coated metal（Aluminum and Nickel） nanoparticles with three different addition amounts into the mixture of chloride salts and natural expanded graphite aiming to improve the thermal conductivity. The preparation processes and its thermal conductivity of this novel composite adsorbent are reported and summarized. Experimental results indicate that the nanoparticles are homogenously dispersed in the composite adsorbent by applying the reported preparation processes. The thermal conductivity of the composite adsorbent can averagely enlarge by 20% when the weight ratio of the added nanoparticles is 10 wt%. Moreover, carbon coated aluminum nanoparticles exhibit more effective enlargement in thermal conductivity than nickel nanoparticles. As for the composite adsorbent of CaCl2-NEG, there is a big reinforcement from 30% to 50% for Al@C nanoparticles, however only 10% in maximum caused by Ni@C nanoparticles. The proposed research provides a methodology to design and prepare thermal conductive chemical composite adsorbent.

Progress in corrosion-resistant coatings on surface of low alloy steel

Low alloy steels are widely used in bridges,construction,chemical and various equipment and metal components due to their low cost and excellent mechanical strength.Information in the literature related to the preparation,advantages and disadvantages,and applications along with research progress of various types of protective coatings suitable for low-alloy steel surfaces is reviewed,while a conclusive and comparative analysis is also afforded to the numerous factors influencing the protective ability of coatings.The characteristics of coatings drawn from the latest published literature are discussed and suggest that the modification of traditional metal coatings and the development of new organic coatings under the consideration of environmental protection,low cost,simplicity and large-scale industrial application are simultaneously proceeding,which holds promise for improving the understanding of corrosion protection in related fields and helps to address some of the limitations identified with more conventional coating techniques.

Corrosion Control of Coated Structural Components in Marine Environment

Tropical waters are with more salinity and harbor millions of micro organisms.Such environmental condition challenges the strength and reliability of marine structures.The behaviour of structural materials due to pitting and uniform corrosion is studied,and a method based on coating is suggested to improve the life cycle ensuring reliability in its functionality.The structural materials like high strength steel and AA6063 were selected for the study and metallic coating performed for evaluation of corrosion resistances.Samples are investigated in chloride concentration of 3.5%NaCl by weight loss measurements and potentiodynamic polarization.The coating was done by electroplating and PVD(Physical Vapour Deposition)method for high strength steel,where as aluminum samples were coated by an electroplating method.The high strength steel samples were mono coated by Ni and Cr using the electroplating method,and composite coating was done with Al-N(Aluminium nitride)and Ti-Al-N(Titanium Aluminium Nitride)by PVD techniques.Scanning electron microscopy(SEM)was used for evaluation of fracture toughness of coating around the pits formed.The investigation showed that the methods and thickness of coating influenced corrosion resistances of the substrate metals.Composite coated samples by PVD showed excellent corrosion resistance properties compared to electroplated samples after the investigations.Finite element analysis was performed by FRANC 2D/L(Fracture Analysis Code)showed a decrease in stress intensity values for composite coated samples of PVD compared to mono coated electroplated samples.Increase in the duty cycle of the structure was observed in the simulation has a result of a decrease in stress intensity values for PVD coated samples.

Synergistic Effect of Mo, W, Mn and Cr on the Passivation Behavior of a Fe-Based Amorphous Alloy Coating

In this work,the electrochemical behaviors of SAM2X5 Fe-based amorphous alloy coating and hard chromium coating were comparatively studied in 3.5 wt% NaCl solution.In comparison with the hard chromium coating,the SAM2X5 coating exhibited a wider and stable passive region with lower passive current density in the potentiodynamic polarization and showed a considerably lower current density at different anodic potentials in the potentiostatic polarization.In order to understand the passivation mechanism of the Fe-based amorphous coating,the components of the passive films formed at various polarization potentials were examined by X-ray photoelectron spectroscopy.The synergistic effect of Mo,W,Mn and Cr in the passive films was systemically analyzed.It has been revealed that Mo and W facilitate the formation of compact and stable Cr2O3 passive film at lower potentials,and the substantial enrichment of Mn in the passive film enhances the passivation ability at relatively higher potentials.The deep understanding of the passivation characteristics in multicomponent alloy systems could provide a guide for the design of corrosion-resistant amorphous alloy coatings for engineering applications.

SURFACE METALLIZATION OF CENOSPHERES AND PRECIPITATORS BY ELECTROLESS PLATING

This paper reports the use of a colloidal Pd0 catalysis system to metallize the surface of precipitators separated from coal fly-ash, and metals such as Cu, Ni etc. are deposited on the precipitators surface. Alternatively, according to the characteristic surface of cenospheres, an Ag coating catalysis system is adopted to first deposit Ag on the cenospheres surface, followed, if necessary, by the deposition of other metals such as Cu, Ni, etc. on the Ag coating to produce monolayer and multilayer metal-coated cenospheres. The surface characteristics and the morphologies of the metal coatings are examined in detail with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. It can be shown that the quality of metal coatings derived from the Ag coating catalysis system, is better than that of the colloidal Pd0 catalysis system.

Probe into deposition mechanism of double pulse electrodepositing Ni-W-P matrix composite coatings containing CeO_2 and SiO_2 nano-particles

Ni-W-P matrix composite coatings reinforced by CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed.The results showed that the composite coatings with amorphous structure were obtained as-deposited.The initial growth behavior had alternatives and the nucleation was inhomogeneous because of obvious composition fluctuation.With the pulse deposition time increasing,some pearlite microstructures of the substrate were covered by some deposits and the composition fluctuation disappeared.Forward pulse currents promoted to form a great number of atomic beams composed of Ni,W and P atoms or CeO2 and SiO2 nano-particles as the core,which inhabited the growth of atomic beams.Reverse pulse currents eliminated concentration polarization and dissolved some surface boss of atomic beams.The solution of W and P atoms within Ni grains and embedding of CeO2 and SiO2 nano-particles within Ni-W-P matrix metal made atomic arrangement disordered.Finally,the atomic beams grew to amorphous small particles.

Coating metals on micropowders by magnetron sputtering

Magnetron sputtering was used to coat various metals on micropowder surfaces. By using this method, the fine particles are better dispersed and can therefore be coated more homogeneously. The micro-powders used include cenospheres from fly ash of coal-burning electric power plants （diameter 40-200 μm and particle density 0.7 ± 0.1 g/cm^3）, as well as carborundum particles of different sizes. Aluminum, silver, copper, cobalt and nickel were used as the coating metals. Tests showed that the coated metal film was compact adhering tightly on the base powders, and the coated powders possess adequate flow properties.