Nano-copper Additives Research Articles

Sustainable nanocomposite films of improved barrier properties for food packaging applications

Environmentally benign, biodegradable materials derived from renewable resources are gaining great consideration in recent times. Food packaging requires FDA approved, lightweight and low cost materials with superior barrier properties for extended shelf life and good flavor/aroma retention. In the present study, polylactic acid (PLA) modified with triethyl citrate (TEC) as a bioplasticizer was reinforced with copper nanoparticles and tested for possible improvement in mechanical and barrier properties. The increase in TEC content upto 8 wt% improved the toughness, beyond 8 wt% there was a decrease in tensile strength and modulus. A nanocomposite film of PLA/TEC/copper nanoparticle (92/8/3 wt%) displayed better barrier properties and optimum mechanical strength. The water vapor permeability and oxygen permeability rate was drastically decreased upon addition of nanocopper.

Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti Substrate

Three coatings suitable for biomedical applications, including the dispersion coating composed of multi-wall carbon nanotubes (MWCNTs), MWCNTs/TiO2 bi-layer coating, and MWCNTs-Cu dispersion coating, were fabricated by electrophoretic deposition (EPD) on Ti Grade II substrate. Optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and nanoindentation were applied to study topography, chemical, and phase composition, roughness, hardness, Young’s modulus, plastic, and elastic behavior. The results showed that the best mechanical properties in terms of biomedical application were achieved for the MWCNTs coating with titania outer layer. Nevertheless, both the addition of nanocopper and titania improved the mechanical resistance of the base MWCNTs coating. Compared to our previous experiments on Ti13Nb13Zr alloy, a general tendency is observed to form more homogenous coatings on pure metal than on the alloy, in which chemical and phase compositions are more complex.

Mechanical Behavior of Bi-Layer and Dispersion Coatings Composed of Several Nanostructures on Ti13Nb13Zr Alloy.

Titanium implants are commonly used because of several advantages, but their surface modification is necessary to enhance bioactivity. Recently, their surface coatings were developed to induce local antibacterial properties. The aim of this research was to investigate and compare mechanical properties of three coatings: multi-wall carbon nanotubes (MWCNTs), bi-layer composed of an inner MWCNTs layer and an outer TiO2 layer, and dispersion coatings comprised of simultaneously deposited MWCNTs and nanoCu, each electrophoretically deposited on the Ti13Nb13Zr alloy. Optical microscopy, scanning electron microscopy, X-ray electron diffraction spectroscopy, and nanoindentation technique were applied to study topography, chemical composition, hardness, plastic and elastic properties. The results demonstrate that the addition of nanocopper or titanium dioxide to MWCNTs coating increases hardness, lowers Young’s modulus, improves plastic and elastic properties, wear resistance under deflection, and plastic deformation resistance. The results can be attributed to different properties, structure and geometry of applied particles, various deposition techniques, and the possible appearance of porous structures. These innovative coatings of simultaneously high strength and elasticity are promising to apply for deposition on long-term titanium implants.

Experimental study on the suspension stability and tribological properties of nano-copper in LCKD-320# lubricating oil

Nano-copper has proven that it has an excellent contribution to the friction-reduction, anti-wear and extreme pressure properties of lubricant, as the lubricating oil additive. However, there are few studies on the application of nano-copper in full formulated lubricating oils. The suspension stability and tribological properties of LCKD-320# lubricating oil with nano-copper of varying concentrations were investigated. The results demonstrated that the nano-copper was synthesized via the liquid-phase reduction method with the average particle size of 128 nm. The additions of Tween80 and Span80 were 2 wt% of nano-copper, respectively, which can maintain a most suitable dispersity and stability. When the addition of nano-copper was 0.3 wt%, the friction coefficient under the load of 20 N and the wear scar area (S) were decreased by 25% and 54.4%, respectively, and the maximum non-seizure loads (PB) was increased by 33% as compared with original LCKD-320# lubricating oil. Testing results showed that the LCKD-320# lubricating oil with or without nano-copper both were conformed to the national lubricant standards. The present work will extend the application of nano-copper additive and introduce a new approach to lubricity for the coal mine machinery in future technological areas.

Tribological behavior and energy dissipation of hybrid nanoparticle-reinforced HPMC composites during sliding wear

In recent years, nanoparticle additives have been frequently used to enhance the tribological properties of polymers, especially in the biopolymer system. In this study, we analyzed the tribological behavior and energy dissipation properties of MoS2 and nano-copper-reinforced biopolymer hydroxypropyl methylcellulose (HPMC) composites. The tribological behavior of the composite was evaluated at low load using a ball-on-disk cycle tester. The addition of MoS2 and nano-copper additives improved the wear resistance and reduced the friction coefficient of the HPMC composites. The addition of both MoS2 and copper additives had a synergistic effect on enhancing the tribology behavior. The dissipation energy results indicated a linear correlation between wear and energy consumed. This study suggests that the wear mechanism varies with the type and quantity of additive, regardless of the normal load applied.

Migration of copper from nanocopper/polypropylene composite films and its functional property

Nanocopper with different concentrations was introduced to homopolymer polypropylene (PP-H) matrix to prepare nanocopper/PP-H composite film. Film appearance, mechanical and thermal properties were investigated. Migration test to 3% acetic acid (w/v) food simulant, film antibacterial ability and human hepatotoxicity were conducted to further evaluate film safeness. FTIR results suggest that nanocopper particles were physically dispersed in PP-H matrix and the addition of nanocopper could significantly improve thermal and mechanical properties of composite films, ensuring its potential utilization for food packaging. Also, the composite film showed great antibacterial ability including Escherichia coli, Staphylococcus aureus, Shigella castellani and Bacillus subtilis. At 70 ℃, when the initial concentration of added nanocopper reached 1% (w/w) or higher, the concentration of copper migrated from film to acetic food simulant would reach to 4.5 μg/g and would start damaging L-02 cells. This study provides important information for the potential utilization of nanocopper in food packaging films.

Effect of Nano-Copper Additives on the Physical Properties of Porous Alumina Ceramics using Graphite Waste as a Pore-Forming Agent

Solid state and sacrificial techniques were used to prepare the porous alumina ceramics. The target of the present research is to investigate the effect of Cu metal addition of nanoscale particle size on the physical properties of porous alumina ceramics using graphite waste as a pore-forming agent. X-Ray Diffraction (XRD), a Field Emission Scanning Electron Microscope (FESEM) and a Transmission and Electron Microscope (TEM) were used to analyse the microstructure and ceramic phases. Different ratios of Cu metal were added (3, 6, 9 and 12 wt.%) at different ratios of graphite waste. The results of this investigation show that with increasing ratios of Cu metal, the porosity decreased while the shrinkage and densities increased. Increases in the density and decreases in the porosity of porous alumina ceramics and the formation of the tenorite (CuO) phase due to sintering at high temperature (1600°C) may lead to improving the strength of porous alumina ceramics. Some potential applications include gas filtration components and as thermal insulation materials.

Exhaust emissions of diesel engines with nano-copper additives

The effects of nano-copper additives were investigated through a thermogravimetric (TG) test, diesel engine bench test, and road driving test. The tests demonstrated that the nano-copper additive presented a good catalytic effect on the combustion of soot particles, which reduced the complete combustion temperature from 580 to 520 °C. The diesel engine bench test showed that particulate matter (PM), CO, and HC emissions were reduced by 99.9%, 81.30%, and 33.33%, respectively. The NOx emissions slightly increased due to the lack of carbon as a reducing substance in the exhaust gas. The road driving test with a diesel vehicle demonstrated that more stringent emission standards can be met without any upgrade to the engine.

The effect of nano-copper additives on the porosity, mechanical properties, and microstructure of alumina ceramics using commercial rice husk ash as a pore former

The aim of the present research is to examine the effect of Cu metal addition in nano-scale particle size on the mechanical properties and porosity of porous alumina ceramics using commercial rice husk ash as pore forming agent and silica (SiO2) source. Porous alumina ceramics reinforced were prepared using nano-scale Cu metal particles as their strengthening phase. Solid-state and sacrificial techniques were used to prepare the porous alumina reinforced ceramics. A field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and transmission and electron microscope (TEM) were used to analyze the microstructure and ceramic phases. Different ratios of Cu metal were added (3, 6, 9, and 12 wt%) at different ratios of commercial rice husk ash. The results of this investigation show that with increasing ratios of Cu metal, the porosity decreased and the mechanical properties increased. The increase in the mechanical properties could be attributed to the decrease in the porosity, the toughening mechanism, increase density of porous alumina ceramics, and formation of the tenorite (CuO) phase due to sintering at high temperature (1600 °C). Some potential applications include purging of gas filtration and thermal insulation.

Effects of Nano Copper Additive on Thermal Conductivity of Magnetorheological Fluid at Different Environment Temperature

Low thermal conductivity of magnetorheological (MR) fluid limits its potential to be applied in high temperature environment. Recently, enhancing thermal conductivity of similar fluids through addition of nanocopper has attracted to address the problem. This paper presents the effects of nanocopper addition on thermal conductivity properties of MR fluid at different environment temperatures. The nanocopper added MR fluid samples were synthesized with carbonyl iron powder in hydraulic oil. The samples were then stabilized with addition of fumed silica and were homogenized using ultrasonic bath. Thermal conductivity of the samples and references material was measured using thermal property analyser. The environment temperature of the samples was controlled by waterbath incubation method. The results showed that enhancement of thermal conductivity with the presence of copper nanoparticles was higher at 40 vol% of CIP compared to 20 vol% of CIP and a slight variation in thermal conductivity of MR fluid was observed in environment temperatures of 30–70°C. This finding leads to development of new class of magnetorheological fluid with enhanced thermal properties.

Tribological Effects of Nano-Copper with Different Diameters in Lubricants

Diameter of nanoparticles plays a vital role in tribological properties of lubricanting oil. Three kinds of nano-copper with different diameters (50nm, 65nm, 80nm) were produced using the electric explosion of metallic wire (EEW), and their diameters were characterized by Scanning Electron Microscope (SEM). The tribological properties of the lubricating oils containing nano-copper additives were investigated using friction wear testing machine, and the wear scar morphology photographs were observed by means of continuously multiple microscope. The results show that lubricanting oil with the large diameter of 80nm copper particles and the weight percentage of 1.0% ~ 1.2% has good characteristic of extreme pressure ; while the lubricanting oil with the small diameter of 50nm copper particles and the weight percentage of 1.2% provides good properties of anti-wear and friction reducing. This has a guiding role in selecting nanooil additives.

Effect of addition of nano-copper and extrusion temperature on the microstructure and mechanical response of tin

Abstract In the present study, 0.35 and 1.1 vol.% of nano-size copper were incorporated into pure tin using hybrid microwave sintering assisted powder metallurgy route. Microwave sintered samples were extruded both at room temperature and at 230 °C. Microstructural characterization studies were conducted on the extruded samples to investigate the distribution characteristics of secondary phase, grains and pores morphology. Resistivity of solder samples was also investigated and found to be not affected by the high temperature extrusion. Room temperature tensile test results revealed that hot extruded Sn–Cu samples exhibited higher strengths and ductility when compared to room temperature extruded samples. On the contrary, the tensile properties of pure tin remained independent of extrusion temperature. An attempt is made in this study to correlate the presence of copper and effect of extrusion temperature on the microstructural evolution and mechanical response of tin.

Effect of Amount of Cu on the Intermetallic Layer Thickness Between Sn-Cu Solders and Cu Substrates

In the present study, Sn-Cu solders were synthesized using pure tin with varying weight percentage of nanosized copper particles (0 wt.%, 0.25 wt.%, 0.43 wt.%, 0.86 wt.%, and 1.35 wt.%) by a powder metallurgy route incorporating microwave-assisted sintering. Intermetallic compound (IMC) layer formation between Sn-Cu solders and Cu substrates was investigated following a reflow process. Isothermal aging studies were also conducted on selected Sn-Cu solders at 150°C for up to 4 weeks. Results revealed that the average IMC layer thickness decreases with the addition of nanocopper up to 0.43 wt.%. Beyond 0.43 wt.% Cu addition, the IMC layer thickness started to increase, and the maximum IMC layer thickness was found for Sn with 1.35 wt.% Cu addition. An attempt was made in this study to correlate the effect of nanocopper additions and aging time on the IMC layer thicknesses.

Preparation and Tribological Properties of Surface-Coated Nano-Copper Additives

In the present work, surface-coated Cu nanoparticles with FCC structure and an average size of 40 nm were prepared by reducing reaction and surface modification technique. The morphology and phase structure of the nano-copper were characterized by transmission electron microscope (TEM). The ball-on-disc tester and ring-on-block tester were performed to study the tribological properties of surface-coated Cu nanoparticles as oil additive. The tests were carried out under the lubrication of 50CC oil alone and oil containing surface-coated nano-copper additives. The morphologies and elementary distributions of the worn surfaces were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometry (EDS), respectively. Results indicate that surface-coated nano-copper additives can significantly improve the wear resistance and load-carrying abilities of 50CC oil, as well as reduce friction coefficient. A soft copper protective film is formed on the worn surface lubricated with oil containing nano-copper additives, which separates the worn surfaces, avoids their direct contact and reduces friction and adhesive wear. Besides, the grooves and small valleys on the worn surfaces are found to be partly filled and repaired by nano-copper, as makes the worn surface repaired and smoother.

Formation and dissociation of HFC134a gas hydrate in nano-copper suspension

The major technical issue in gas hydrates energy storage systems is how to increase the refrigerants-water mass and heat transfer and how to realize a rapid formation of clathrate hydrate. Borrowing ideas from heat transfer enhancement of the fluid with the addition of nano-sized particles, the formation and dissociation of HFC134a (CH 2 FCF 3 ) hydrate were studied in nano-copper suspensions of different mass fractions. The experimental results indicate that the addition of nano-copper enhances the heat and mass transfer process of HFC134a hydrate formation, which was shortened with the increasing mass fraction of nano-copper. Compared with the dissociation pressure at a given temperature below the critical dissociation point, a significant upward shift of the dissociation pressure of the HFC134a hydrate formed in the nano-fluid was observed. The critical dissociation point shifts from the former point (283.15 K, 414.86 kPa) to the latter one (282.65 K, 401.35 kPa), and the dissociation curve does not shift with the change of mass fraction of the nano-copper.

Study of friction reduction by nanocopper additives to motor oil

Nanoscale copper powder has been produced using such an energetic method as the electric explosion of metallic wire (“EEW” process) in an inert gas. The crystalline structure of nanoparticles has been characterized by HRTEM and particle size distribution has been measured. The nanopowder has been added to motor oil and friction coefficient measured to compare with that of pure oil. SEM characterization of the worn surfaces and X-ray microanalysis have been performed to reveal both changes in topology of the worn surfaces and traces of copper.