Mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hot-roll bonding

This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 Pa.Non-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into MgO.In addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the interface.This process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.

Surface Characteristics of Rare Earth Treated Carbon Fibers and Interfacial Properties of Composites

Effect of rare earth treatment on surface physicochemical properties of carbon fibers and interfacial properties of carbon fiber/epoxy composites was investigated, and the interfacial adhesion mechanism of treated carbon fiber/epoxy composite was analyzed. It was found that rare earth treatment led to an increase of fiber surface roughness, improvement of oxygeaa-containing groups, and introduction of rare earth element on the carbon fiber surface. As a result, coordination linkages between fibers and rare earth, and between rare earth and resin matrix were formed separately, thereby the interlaminar shear strength （ILSS） of composites increased, which indicated the improvement of the interfacial adhesion between fibers and matrix resin resulting from the increase of carboxyl and carbonyl.

Effect of dissolved components of malachite and calcite on surface properties and flotation behavior

In general,malachite is recovered via sulfidization–xanthate flotation,although many unsatisfactory flotation indexes are frequently obtained as a result of the presence of associated calcite.This phenomenon occurs because the dissolved components of malachite and calcite affect the flotation behavior of both minerals.In this study,the effect of the dissolved components derived from malachite and calcite on the flotation behavior and surface characteristics of both minerals was investigated.Flotation tests indicated that malachite recovery decreased when the calcite supernatant was introduced,while the presence of the malachite supernatant increased the recovery of calcite.Dissolution and adsorption tests,along with zeta potential measurements,X-ray photoelectron spectroscopy,Fourier transform infrared spectrometry,and timeof-flight secondary ion mass spectrometry demonstrated that the Ca species in the calcite supernatant were adsorbed on the malachite surface,which hindered the interaction of Na2S with malachite,thereby resulting in the insufficient adsorption of sodium isoamyl xanthate(NaIX)on the surface of malachite.By contrast,the Cu species in the malachite supernatant were adsorbed on the calcite surface,and they provided active sites for the subsequent adsorption of Na_(2)S and NaIX.

Elucidation of the structure, antioxidant, and interfacial properties of flaxseed proteins tailored by microwave treatment

The microwave treatment is commonly applied to flaxseed to release nutrients, inactivate enzymes, remove cyanogens,and intensify flavors. The current study aimed to explore the influences of microwave exposure on the antioxidant and interfacial properties of flaxseed protein isolates(FPI), focusing on the altering composition and molecular structure.The results showed that after microwave exposure(700 W, 1–5 min), more compact assembly of storage proteins and subsequent permeation by membrane fragments of oil bodies occurred for cold-pressing flaxseed flours. Moreover, the particle sizes of FPI was progressively reduced with the decrement ranged from 37.84 to 60.66%(P<0.05), whereas the zeta potential values initially decreased and then substantially recovered during 1–5 min of microwave exposure. The conformation unfolding, chain cross-linking, and depolymerization were sequentially induced for FPI based on the analysis of fluorescence emission spectra, secondary structure, and protein subunit profiles, thereby affecting the dispersion or aggregation properties between albumin and globulin fractions in FPI. Microwave exposure retained specific phenolic acids and superior in vitro antioxidant activities of FPI. The inferior gas–water interface absorption and the loose/porous assembly structure were observed for the foams prepared by FPI, concurrent with obviously shrinking foaming properties upon microwave exposure. Improving oil–water interface activities of FPI produced the emulsion droplets with descending sizes and dense interface coating, which were then mildly destabilized due to the lipid leakage and weakened rheological behavior with microwave exposure extended to 5 min. Our findings elucidated that microwave treatment could tailor the application functionality of protein fractions in flaxseed based on their in situ structural remodeling.

Effects of laser energy on the surface quality and properties of electrodeposited zinc-nickel-molybdenum coatings

As a substitute for toxic cadmium coatings in the aerospace industry,zinc-nickel coatings have excellent application prospects,and their properties can be improved by adding molybdenum.In this study,laser-assisted electrodeposition is used to improve the surface quality and properties of Zn–Ni–Mo coatings,with investigation of how laser energy in the range of 0–21.1μJ affects their element content,surface morphology,crystal phase,microhardness,residual internal stress,and corrosion resistance.The laser irradiation accelerates the electrodeposition,refines the grain size,improves the hydrogen adsorption,and reduces the residual tensile stress,and a laser energy of 15.4μJ gives the highest Ni and Mo contents and the lowest Zn content,as well as the optimum surface morphology,microhardness,residual internal stress,and corrosion resistance of the coating.

Adjusting the interfacial adhesion via surface modification to prepare high-performance fibers

Ultra-high molecular weight polyethylene(UHMWPE)fiber is a new kind of high-performance fiber.Due to its excellent physical and chemical characteristics,it is widely used in various fields.However,the surface UHMWPE fiber is smooth and demonstrates no-polar groups.The weak interfacial adhesion between fiber and resin seri-ously restricts the applications of UHMWPE fiber.Therefore,the surface modification treatments of UHMWPE fiber are used to improve the interfacial adhesion strength.The modified method by adding nanomaterials elu-cidates the easy fabrication,advanced equipment and proper technology.Thus,the progress of UHMWPE nanocomposite fibers prepared via adding various nanofillers are reviewed.Meanwhile,the effects of other various methods on surface modification are also reviewed.This work advances the various design strategies about nano technologies on improving interfacial adhesion performance via treatment methodologies.

Interfacial reaction behavior and mechanical properties of 5A06 Al alloy soldered with Sn-1Ti-xGa solders at a low temperature

Active soldering of 5A06 Al alloy was performed at 300 ℃ by using Sn-1Ti and Sn-1Ti-0.3Ga active solders, respectively. Theeffects of soldering time on the microstructure and mechanical properties of the joints were investigated. The results showed that the Sn-1Tisolder broke the oxide film on the surface of the Al substrate and induced intergranular diffusion in the Al substrate. When Ga was added tothe solder, severe dissolution pits appeared in the Al substrate due to the action of Sn-1Ti-0.3Ga solder, and many Al particles were flakedfrom the matrix into the solder seam. Under thermal stress and the Ti adsorption effect, the oxide film cracked. With increasing solderingtime, the shear strength of 5A06 Al alloy joints soldered with Sn-1Ti and Sn-1Ti-0.3Ga active solders increased. When soldered for 90 min,the joint soldered with Sn-1Ti-0.3Ga solder had a higher shear strength of 22.12 MPa when compared to Sn-1Ti solder.

Effect of Fibre Size on Mechanical Properties and Surface Roughness of PLA Composites by Using Fused Deposition Modelling (FDM)

Naturalfibre as a reinforcing agent has been widely used in many industrial applications.Nevertheless,several factors need to be considered,such as the size and weight percentage of thefibre used in binding.Using fused deposition modelling(FDM),this factor was investigated by varying the size of naturalfibre as the responding variable with afixed weight percentage of kenaffibre.The process of modifying the naturalfibre in terms of size might increase the dispersion of kenaffibre in the polymer matrix and increase the adhesion bonding between thefibre and matrix of composites,subsequently improving the interfacial bonding between these two phases.In this paper,the effect offibre size was evaluated by performing the mechanical test,Scanning Electron Micrograph(SEM)to observe the morphology of the composites,and also by surface analysis.The surface roughness was visualised using a 3D profilometer and thefigure was illustrated as colour shading in the image.The composite withfibre size≤100μm displayed better tensile andflexural strength,compared to other sizes.In conclusion,by reducing the size of thefibre,the composites could develop high strength performance for industrial applications.

Synthesis and Interfacial Properties of Bio-Based Zwitterionic Surfactants Derived from Different Fatty Acids in Non-Edible Vegetable Oils

Waste cooking oils and non-edible vegetable oils are abundant and renewable resources for bio-based materials which have showed great potential applications in many industries.In this study,five fatty acids commonly found in non-edible vegetable oils,including palmitic acid,stearic acid,linoleic acid,linolenic acid,ricinoleic acid,and their mixtures,were used to produce bio-based zwitterionic surfactants through a facile and high-yield chemical modification.These surfactants demonstrated excellent surface/interfacial properties with the minimum surface tensions ranging from 28.4 mN/m to 32.8 mN/m in aqueous solutions.The interfacial tensions between crude oil and surfactant solutions were remarkably reduced to lower values ranging from 0.0028 mN/m to 0.1983 mN/m without the aid of extra alkali,which particularly implied a great potential application in enhanced oil recovery.Meanwhile,these bio-based surfactants also showed good wetting properties(contact angles of~51°comparing with that of double distilled water,92.04°)and appropriate predicted biodegradability(degradation order of“weeks”for bio-based surfactants synthesized from saturated fatty acids,and“months”for those synthesized from unsaturated fatty acids).Bio-based surfactants synthesized from unsaturated fatty acids showed better interfacial properties in reducing interfacial tension between crude oil and formation water.The bio-based surfactants presented in this study are alternative substitutes for traditional petroleum-based surfactants in various surfactant application fields.

Bio-leaching effects of Leptospirillum ferriphilum on the surface chemical properties of pyrite

Leptospirillum ferriphilum cultured using different energy sources(either soluble ferrous ion or pyrite) changed the surface properties of pyrite.Cell adsorption,zeta-potential,hydrophobicty,FT-IR spectra and surface morphology were investigated.Adhesion of bacterial cells to the pyrite surface is a fast process.Furthermore,the adsorption of cells grown in pyrite is greater than of cells grown in soluble ferrous ion.The Iso-Electric Point(IEP) of pyrite treated with L.ferriphilum approaches that of the cells themselves.The contact angle of the pyrite surface was observed to decrease due to the surface formation of some hydrophilic substances during bio-leaching.Changes in pyrite surface properties after bacterial treatment support the idea that ferric ion plays an important role and that indirect bio-oxidation is the principal mechanism of pyrite bio-leaching.

Surface modification of wollastonite by the mechano-activated method and its properties

Surface modification of wollastonite particles using titanate as a modification agent incorporated by simultaneous wet ultra-fine grinding in a laboratory stirred mill was investigated.The physical,physic-chemical and application properties of the modified wollastonite were measured and evaluated.The results showed that grinding intensity markedly influences the modification effect because of the mechano chemical effect.The hydrophilic surface of wollastonite was turned into a hydrophobic one after modification.The interaction between titanate and wollastonite under wet grinding circumstances was studied.It was suggested that physical adsorption and chemical adsorption of titanate coexisted on the wollastonite surface.The mechanical properties of polyethylene（PE） filled with the modified wollastonite powder were markedly improved.

Preparation and Surface Properties of Silicon-Containing Waterborne Polyurethane Functionalized with Fluorine-Containing Acrylate and Micro-Nano Silica

In order to prepare hydrophobic waterborne polyurethane coatings with better performances, the silicon-containing waterborne polyurethane（SiWPU） with functional chain extender hydroxyethyl acrylate（HEA） was prepared first, and then a series of silicon＆fluorine-containing polyurethane/acrylate（FSiPUA） emulsions were obtained with flourine containing acrylic monomer by seed emulsion polymerization, introducing micro-nano SiO2 into FSiPUA emulsion to make the final hybrid emulsion. The properties of Si WPU, FSiPUA and SiO2/FSiPUA were investigated by fourier transform infrared spectra（FTIR）, transmission electron microscope（TEM）, Scanning Electron Microscope（SEM） and some other analytical methods. The results revealed that FSiPUA emulsion particles possessed composite core-shell structure and FSiPUA films with suitable ratio performed better than Si WPU films in hardness, water resistance and solvent resistance. The SiO2/FSiPUA films with micro-nano dual roughness structure showed a water contact angle of 136° with good resistance to acid and alkali.

Effect of surface preparation on corrosion properties and nickel release of a NiTi alloy

Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.

Effect of rare earths surface treatment on tribological properties of carbon fibers reinforced PTFE composite under oil-lubricated condition

The effect of rare earths （RE） surface treatment of carbon fibers （CF） on tribological properties of CF reinforced polytetrafluoroethylene （PTFE） composites under oil-lubricated condition was investigated. Experimental results revealed that RE treated CF reinforced PTFE （CF/PTFE） composite had the lowest friction coefficient and wear under various applied loads and sliding speeds compared with untreated and air-oxidated composites. X-ray photoelectron spectroscopy （XPS） study of carbon fiber surface showed that, after RE treatment, oxygen concentration increased obviously, and the amount of oxygen-containing groups on CF surfaces were largely increased. The increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix. With strong interfacial adhesion of the composite, stress could be effectively transmitted to carbon fibers; carbon fibers were strongly bonded with VITE matrix, and large scale rubbing-off of PTFE be prevented, therefore, tribological properties of the composite was improved.

Prediction of surface and interfacial tension based on thermodynamic data and CALPHAD approach

In this article, following a brief introduction concerning experimental measurements of surface and interfacial tensions, methods for calculating surface tension and surface segregation for binary, ternary, and multicomponent high-temperature melts based on Bulter＇s original treatment [ 1] and on available physical properties and thermodynamic data, especially excess Gibbs free energies of bulk phase and surface phase versus temperature obtained from thermodynamic databases using the calculation of phase diagram （CALPHAD） approach, with special attention to the model parameter β, have been described. In addition, the geometric models can be extended to predict surface tensions of multicom- ponent systems from those of sub-binary systems. For illustration, some calculated examples, including Pb-free soldering systems and phase-diagram evaluation of binary alloys in nanoparticle systems are given. On the basis of surface tensions of high-temperature melts, interracial tensions between liquid alloy and molten slag as well as molten slag and molten matter can be calculated using the Girifalco-Good equation [2]. Modifications are suggested in the Nishizawa＇s model [3] for estimation of interracial tension in liquid metal （A）/ceramics （MX） systems so that the calculations can be carried out based on the sublattice model and thermodynamic data, without deliberately differentiating the phase of MX at high temperature. Finally, the derivation of an approximate expression for predicting interfacial tension between the high-temperature multicomponent melts, employing Becker＇s model [4] in conjunction with Bulter＇s equation and inteffacial tension data of the simple systems is described, and some examples concerning pyrometallurgical systems are given for better understanding.

Interfacial microstructure and mechanical properties of Ti-6Al-4V/Al7050 joints fabricated using the insert molding method

Ti-6Al-4V/Al7050 joints were fabricated by a method of insert molding and corresponding interfacial microstructure and mechanical properties were investigated. The interfacial thickness was sensitive to holding temperature during the first stage, and a good metallurgical bonding interface with a thickness of about 90 μm can be obtained at 750°C. X-ray diffraction, transmission electron microscopy, and thermodynamic analyses showed that the interface mainly contained intermetallic compound TiAl_3 and Al matrix. The joints featured good mechanical properties, i.e., shear strength of 154 MPa, tensile strength of 215 MPa, and compressive strength of 283 MPa, which are superior to those of joints fabricated by other methods. Coherent boundaries between Al/TiAl_3 and TiAl_3/Ti were confirmed to contribute to outstanding interfacial mechanical properties and also explained constant fracture occurrence in the Al matrix. Follow-up studies should focus on improving mechanical properties of the Al matrix by deformation and heat treatment.

Study on the surface properties of surface modified silicone intraocular lenses

AIM: To prepare a new-type soft intraocular lens (IOL) that silicone intraocular lenses (IOLs) were modified by surface modification technique to assess IOLs biocompatibility. METHODS: With the technique of ion beam combined with low temperature and low pressure plasma, the surface characteristics of the IOLs including physical and optical properties were determined by the instruments of IOLs resolution, UV/VIS scanning spectrophotometer, contact angle measurement system, electron spectroscopy for chemical analysis (ESCA) and scanning electron microscope (SEM). RESULTS: The color of titanium (Ti) modified IOLs was light yellow and that of titanium nitride (TiN) modified IOLs was light brown. The absorptive degree of ultraviolet rays and the hydrophilicity of the surfaces of modified IOLs were increased, and appeared suitable chemical compositions. The resolution of unmodified and modified IOLs reached normal standard. The surfaces of unmodified and Ti-modified IOLs appeared uniform. The surfaces of TIN-modified IOLs presented fine porcelain structure. CONCLUSION: The optical properties of all IOLs and the surface morphology of the modified IOLs were not affected by modification processes. The surface properties of the modified IOLs were improved.

Surface chemical properties and pore structure of the activated coke and their effects on the denitrification activity of selective catalytic reduction

In order to study the mechanism of selective catalytic reduction of activated coke to remove NO in low-temperature flue gas and provide some theoretical basis for the development of related technologies.The pore sizedistribution and BET specific surface area of AC were obtain by data analyzing of N2 adsorption/desorption isotherm at -196 ℃ and carbon matrix and surface chemistry of virgin activated coke samples were characterized by acid-base titration and XPS.The process of selective catalytic reduction of activated coke (AC) samples with NH3 as reducing agent was studied in a fixed bed reactor at 150 ℃.The result shows that pore size distribution or BET specific surface of activated cokes have not correlation with denitrification activity for SCR.The NO reduction activities of the activated cokes are apparent to increase with their surface oxygen element content and total amount of acidic sites.Obviously there is good linear relationship between the NH3 adsorption capacity and activity for SCR with linear correlation coefficient 0.943.It has been presented that adsorption of NH3 on acidic functional groups in the edge of large polycyclic aromatic ring of activated coke is key rate controlling step in the SCR heterogeneous catalytic reaction.

COMPARISON OF SURFACE PROPERTIES OF Ti-6Al-4V COATED WITH TITANIUM NITRIDE, TiN+TiC+Ti(C,N)/DLC, TiN/DLC AND TiC/DLC FILMS BY PLASMA-BASED ION IMPLANTATION

The surface properties of Ti-6Al-4V alloy coated with titanium nitride, TiN+TiC+Ti(C,N)/DLC (diamond like carbon), TiN/DLC and TiC/DLC films by plasma-based ion implantation (PBII) with nitrogen, PBII with nitrogen then acetylene, PBII with nitrogen then glow discharge deposition with acetylene plus hydrogen and PBII with acetylene then glow discharge deposition with acetylene plus hydrogen respectively were studied. The corresponding films are found getting dimmer, showing light gold or gold, smoky color (uneven), light red in black (uneven), and graphite black separately. The corresponding film resistivities are given. Antioxidation ability of the titanium nitride film is poor, while the existence of carbon (or carbide) improves the antioxidation ability of the films. Having undergone excellent intermediate transitional region of nitrogen and carbon implantation, the top DLC layer of the TiN+TiC+Ti(C,N)/DLC multilayer are formed after the carbon implantation has the best adhesion with the substrate among all the multilayers. Although microhardness of the samples increases in the order of coatings of titanium nitride, TiN/DLC, TiN+TiC+Ti(C,N)/DLC and TiC/DLC, the TiN/DLC and TiC/DLC multilayers have greater brittleness as compared with other films.

The Impact of Surface Properties on Downward Surface Shortwave Radiation over the Tibetan Plateau

The complexity of inhomogeneous surface-atmosphere radiation transfer is one of the foremost problems in the field of atmospheric physics and atmospheric radiation. To date, the influence of surface properties on shortwave radiation has not been well studied. The daily downward surface shortwave radiation of the latest FLASHFlux/CERES （Fast Longwave And Shortwave Fluxes_Time Interpolated and Spatially Averaged/Clouds and the Earth＇s Radiant Energy System） satellite data was evaluated against in situ data. The comparison indicated that the differences between the two data sets are unstable and large over rugged terrain compared with relatively flat terrain, and the mean absolute error of the satellite products reaches 31.4 W m-2 （12.3%） over rugged terrain. Based on the SSF （single satellite footprint）/CERES product, the influence of surface properties on the distribution of downward surface shortwave radiation （DSSR） was analyzed. The influence of surface properties on DSSR over the Tibetan Plateau is about twice as large as that in two other regions located at the same latitude （eastern China-western Pacific and subtropical North Pacific）. A simulation was carried out with the help of the I3RC （International Intercomparision of Three-Dimensional Radiation Code） Monte Carlo 3D radiative transfer community model. The results showed that DSSR increases as surface albedo increases. Moreover, the impact of surface albedo on DSSR is larger if the spatial distribution of clouds is more non-uniform. It is hoped that these results will contribute to the development of 3D radiative transfer models and the improvement of satellite inversion algorithms.