Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying(NCES)Using Different Types of Vegetable Oils as Base Fluids of External Fluid

The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic spraying(NCES)can enhance the performance of MQL more comprehensively.However,it is largely influenced by the base fluid of external fluid.In this paper,the lubrication property and machining performance of NCES with different types of vegetable oils(castor,palm,soybean,rapeseed,and LB2000 oil)as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids.The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances.The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid,NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7%and 7.6%-26.5%,respectively.The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2%and 3.6%-11.2%lower than those for NCES with other vegetable oils as the base fluids of external fluid,respectively.When LB2000/multi-walled carbon nanotube(MWCNT)water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1,NCES showed the best milling performance.This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.

Microstructure of Ni–Al powder and Ni–Al composite coatings prepared by twin-wire arc spraying

Ni–Al powder and Ni–Al composite coatings were fabricated by twin-wire arc spraying（TWAS）. The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni–Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni_3Al, Al_2O_3, and NiO. The Ni–Al phase and a small amount of Al_2O_3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni–Al composite coatings were characterized by SEM, EDS, X-ray diffraction（XRD）, and transmission electron microscopy（TEM）. The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and Ni Al in addition to a small amount of Al_2O_3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, Ni Al, and Ni_3Al in addition to a small amount of Al and Al_2O_3, and Ni Al and Ni_3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl_3 precipitates and a Ni–Al–O amorphous phase formed in the matrix of the Ni solid solution in the original state.

Application of WC cermet sprayed composite coating in hot-dip galvanizing lines

With the rapid development of the automobile industry, the use of galvannealed and galvanized steel sheets in automobiles is on the rise. These sheets must meet very high surface quality requirements. The surface treatment of line rolls is known to have a great impact on strip quality. To prevent dusts such as zinc ash from pressing into the strip surface, we used a composite thermal spray surface treatment technique to treat rolls. The successfully developed tungsten carbide （WC） ＋ Ni-P composite plating technology improved the quality of the tungsten carbide thermally sprayed WC roll surface. This technique is also helpful to control defects such as adhered foreign materials in hot-dip galvanized automobile outer panel surfaces.

Micro-nano structured functional coatings deposited by liquid plasma spraying

Inspired by the micro-nano structure on the surface of biological materials or living organisms,micro-nano structure has been widely investigated in the field of functional coatings.Due to its large specific surface area,porosity,and dual-scale structure,it has recently attracted special attention.The typical fabrication processes of micro-nano structured coatings include sol-gel,hydrothermal synthesis,chemical vapor deposition,etc.This paper presents the main features of a recent deposition and synthesis technique,liquid plasma spraying(LPS).LPS is an important technical improvement of atmospheric plasma spraying.Compared with atmospheric plasma spraying,LPS is more suitable for preparing functional coatings with micro-nano structure.Micro-nano structured coatings are mainly classified into hierarchical-structure and binary-structure.The present study reviews the preparation technology,structural characteristics,functional properties,and potential applications of LPS coatings with a micro-nano structure.The micro-nano structured coatings obtained through tailoring the structure will present excellent performances.

Numerical analysis and capacity evaluation of composite sprayed concrete lined tunnels

Spray-applied membranes for waterproofing of sprayed concrete tunnels have led to the possibility of shear transfer between primary and secondary linings through the membrane interface,with the potential for reducing overall lining thickness.Laboratory tests have shown a reasonable degree of composite action in beam specimens.In this study,a numerical model previously calibrated against such tests is applied to a whole tunnel,considering soil–structure interaction and staged lining construction.The model shows composite action,and load sharing between the lining layers is expected in the tunnel as in the beams.Parametric studies over the practical range of interface stiffness values show that composite action is maintained,although at high interface stiffness,excessive bending may be imposed on the secondary lining,requiring additional reinforcement.An effcient composite shell design with minimal additional rein-forcement is achievable if the secondary lining thickness is reduced as compared to current practice.Robustness of the system,measured in terms of the interface’s ability to transfer stress under unequal loading causing distortion on the tunnel,is found to be generally ade-quate.However,adjacent construction in close proximity may provide insuffcient margin on membrane tensile de-bonding,particularly if the membrane is partially or fully saturated.

Influence of Atmospheric Plasma-Sprayed Composite Cathode on the Performance of Solid Oxide Fuel Cells

Ni-Al2O3 cermet supported tubular solid oxide fuel cells(SOFCs)with different cathodes were fabricated by thermal spraying.The anode,electrolyte and cathode were deposited by atmospheric plasma spraying(APS)aimed at reducing the manufacturing cost of SOFCs.Three porous composite cathodes of lanthanum strontium manganite(LSM)and yttria-stabilized zirconia(YSZ),lanthanum strontium cobalt oxide(LSC)and YSZ,LSC and scandia-stabilized zirconia(ScSZ)were prepared to investigate influence of cathode constitutions on the cell's performance.The electrode polarization can be improved through using a composite cathode.The maximum power density of the cell with APS YSZ electrolyte and LSC/ScSZ composite cathode is increased about 12%than pure LSM cathode.The maximum output power density of the cell with APS ScSZ electrolyte and LSC/ScSZ composite cathode reaches 1.0 W/cm 2 at 1000 o C.The further optimization of the performance of plasma-sprayed composite cathode can be made through improving the interface contact between YSZ electrolyte and composite cathode.