Advanced Materials Research Vols. 652-654

Abstract: Electrochemical corrosion behavior of corrosion-resistant steel for cargo oil tank were studied under different immersion corrosion time, and tests were carried in the PH=0.85, 10% NaCl solution, which temperature were 30°C. The electrochemical tested by the electrochemical polarization curve and electrochemical impedance spectroscopy (EIS), and the corrosion morphology and distribution of corrosion pit were observed under the metallography. The results indicate that along with the time extending, the corrosion potential of material moved from positive to negative, and then moved to positive. The corrosion current density also first reduced, then followed by the increasing and then decreasing, which indicated that the corrosion products of sample surface experienced a growth - dissolution - growth process, and presented a periodic corrosion rule. The position of corrosion pit mainly occurred around the pearlite.

Abstract: The effects of friction load and ultrasonic vibration on friction reduction and anti-wear properties of Al₂O₃/Al₂O₃ ceramic frictional pairs under oil lubrication were investigated by a modified MFT-R4000 reciprocating friction and wear tester. The mechanism of friction reduction and anti-wear under ultrasonic vibration was discussed. The results showed that, the ultrasonic vibration could influence the friction reduction and anti-wear properties of Al₂O₃/Al₂O₃ ceramic friction pairs due to it could reduce the stress between the friction pairs and destroy the oil film on the surface of samples. When the friction frequency was 2Hz, the ultrasonic vibration could reduce the friction coefficient within experiment load range. When the loads were 70N, 80N, 90N and 100N, the average friction coefficient were reduced by 16.1%, 14.5%, 9.7% and 2.6%,and wear volume of frictional pairs decreased 35%、32%、31% and 12%.

Abstract: With the help of applying the welding method of DC transverse magnetic field plasma arc surfacing, the powder of Co-based alloy is built up welding on surface of low carbon steel, the refinement effect of primary and secondary crystal structure inflicted by the magnetic field is confirmed through hardness test, wear resistance test, metallographic test and XRD analysis. And study systematically the law of DC transverse magnetic field influencing the surfacing layer metal hardness and wear resistance. The results show that the mechanical properties of surfacing layer achieve the best value when appropriate overlaying welding current match with magnetic current. "Magnetic blow" can be improved with the addition of transverse magnetic field, improving the stability of overlaying welding arc process.

Abstract: This work reported on exploring a low cost preparation technology for coated conductor. The epitaxial of La_0.4Sr_0.6TiO₃ conductive buffer layer on NiW substrate was achieved by metal organic deposition. Excellent in-plane and out of plane alignment is confirmed via XRD. YBCO film was fabricated by electrophoretic deposition (EPD). We used buffered (LSTO) Ni-W substrate and Ni plate as cathode and anode respectively. The critical current density of YBCO coating is more than 1000A/cm2 (0T, 77K).

Abstract: Al3Ti-based intermetallic compound coatings were formed on AA6063 aluminum alloy by laser cladding. The microstructure, wear and corrosion behaviors were investigated. The results showed that, the laser cladding coatings were made up of Al3Ti dendrites, interdendritic α-Al and uniform distribution of TiC particles, and showed good bonding to the substrate. The microhardness, wear and corrosion resistances of the laser cladding coatings greatly increased compared to the substrate. And with the addition of TiC particles to the coating, the superficial properties are improved simultaneously.

Abstract: WS₂ has excellent tribological properties; it is emerging of lubricating materials. MoS₂ is commonly used solid lubricants and wide range of applications, but its poor heat resistance. WS₂ can well make up for the inadequate performance of the MoS₂, but uses it as a solid lubricant in performance research on metallic materials. By friction and wear testing, the paper gets feasibility analysis of the application that WS₂ instead of MoS₂ in the field of solid lubrication, while exploring the synergies between them, laying the foundations for the manufacture of new types of composite lubrication coatings.

Abstract: Electroless Ni-P plating on Mg-7Al alloy by chemical conversion pretreatment was investigated. Morphology of electroless nickel plating coatings and phase compositions were measured by SEM, EDX and XRD. The optimized bath composition parameters were determined through orthogonal design. The morphology of electroless nickel plating coatings on Mg-7Al alloy exhibits a nodular structure and resembles the surface of a cauliflower and the coating is compact and consists of amorphous Ni-P coating. Potentiodynamic polarization curves of the Ni-P coatings in 3.5% NaCl show that the Ni-P coating extensively improves the corrosion resistance of Mg-7Al alloy and the highest corrosion potential reached to -0.54V vs. SCE(saturated calomel electrode). The results of the orthogonal experiment show that Nickel Sulfate of 25 g/L, Sodium Hypopho-sphate of 25 g/L and Citrate 7.5 g/L can be considered as the optimum bath content parameters for electroless Ni–P plating on Mg-7Al alloy and Nickel Sulfate has more effect on corrosion potential than Sodium Hypophosphate and Citrate..

Abstract: Trace explosives detection plays a more and more important role in military, civilian and opposition to state terrorism application. Through sol-gel technique and spin coating technology, three different types of surfactants as structure-directing agent， a series of different pore size mesoporous silica thin films with two-dimensional hexagonal structure doped by silylated naphthol fluorescence dye were successfully fabricated. By using fluorescence spectra method, different films doping fluorescence dye were sensed toward nitro explosive vapor such as 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), octahydro -1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and exhibit rapid response rate and extremely high fluorescent quenching efficiency, close to 72% after 60s response to TNT. The results clearly show that mesoporous silica films, with different porous size and structure, easily to be prepared and own high sensitivity, could be used as a new alternative of trace explosive detecting material.

Abstract: Using molecular dynamics simulation, the influence factors of deposition process, such as cluster incident velocity, material hardness and so on, were studied. The cluster incident velocity influences the combination strength between the substrate and cluster greatly. The higher the cluster velocity is, the stronger the combination strength is, and the faster the cluster forms the crystalline structure like the substrate. Higher temperature of the substrate and the cluster will improve the combination strength. The size of the cluster influences the effect of combination as well. The larger the cluster is, the stronger the combination strength is. If a soft cluster impacts on a hard substrate, because of lack of enough deformation at the interface of the substrate, it is difficult to form the effective combination. If a hard cluster impacts on a soft substrate, the lattice defects occur and the cluster takes a longer time to form crystalline structure.

Abstract: The microstructure evolution of different stacking fault energy metal materials, copper, aluminum alloy and magnesium alloy during ECAP, were investigated based on the finite element simulation software DEFORM-3D. Analyzed the effect on the microstructure of deformation speed, extrusion passes and stacking fault energy. The results show that, the grain size is decreased with the pass number increasing, and deformation speed has no obvious effect on the microstructure. The high SFE metal, aluminum, shows a finer grains than the medium SFE metal, copper.