Advanced Materials Research Vol. 510

Abstract: Laser surface cladding of Ti6Al4V alloy by Ti+Al+C powders (Titanium and carbon powders with an atomic ratio of 1:1 were mixed with 20-60wt.% aluminum powders) was investigated using CO₂ laser. TiC particles were in situ formed mainly during the solidification and sizes of TiC particles were varied according to different contents of aluminum powders in the Ti+Al+C system. The results show that the coating had good metallurgical bonding with substrate when Al content was 20% or 40%. The microhardness of coating is 738HV0.5 which was 2 times as that of the Ti6Al4V alloy approximately. The wear resistance of TiC/Al ceramic layer was approximately 3 times greater than that of the Ti6Al4V substrate. 1

Abstract: Modified nanoZnO/WPU hybrid material was synthesized by three different ways in this paper, the effect of the addition method and content of modified nanoZnO on the hybrid material were discussed. The results showed that modified nanoZnO was added in polymerization process, the hybrid emulsion stability and the coating films mechanical strength all with excellent performance. The appropriate addition of nanoZnO modified by titanate coupling agent can improve the ultraviolet weatherproof, tensile strength, elongation at break even the abrasion resistance of the hybrid material. When modified nanoZnO content was 0.3%, the comprehensive performance of hybrid material was the best.

Abstract: The stability and electronic structures of Al or/and P doped single-walled SiC nanotubes (SWSiCNTs) are investigated by the first-principles theory. It is found that the ones with P atom located at Si site are most energetically favorable both for armchair and zigzag SWSiCNTs, which means that P atom is prone to substitute Si atom. In the same time, we found that the formation energy of Al substituting Si atom is lower than that of Al substituting C atom. The energetic disadvantages of P or Al atom located at C site in SWSiCNTs may be due to the obviously structural distortion in view of that the Al and P atoms are much bigger than C atom. The SWSiCNTs can be routinely modified ranging from p-type semiconductor to n-type by Al and P substitution doping. These results are expected to give valuable information in building nanoscale electronic devices.

Abstract: In the present investigation, resin transfer molding has been used to produce high quality carbon fiber epoxy composites and nanotube-reinforced carbon fiber epoxy composites. To study the influence of carbon nanotubes (CNTs) on improving the mechanical properties and fatigue life, the tension-tension fatigue test has been carried out on those two kinds of material in the fiber direction. The damage mechanism in the fiber directions was analyzed by X-ray radiography and electron microscopy. The results show that CNTs pulled out, rapture and bridged cracks during the test, the results also show that CNTs possess an obvious potential on improving the property of carbon fiber epoxy composite, especially for properties that dominated by matrix.

Abstract: In this paper a novel colorless and salt-tolerant silver-histidine complex doped montmorillonite (Na-MMT) antibacterial agent (SHMMT) power was synthesized by ion exchange reaction using silver-histidine complex ion [Ag (his)] ⁺ as precursor, and characterized by atomic absorption spectrophotometer (AAS) and power X-ray diffraction (XRD). The antibacterial activities against Pseudoalteromonas carrageenovora were examined by a modified broth dilution test and the plate counting method. The salt-tolerant property was determined by the antibacterial activities of the sea water soaked SHMMT. The results showed that the Ag loading amount of SHMMT powder reached 1.7mmol/g, far more than the cationic exchange capacity (CEC) of Na-MMT. SHMMT powder had high bacterial activity eventhough it was soaked in the sea water for 30 days. 1

Abstract: The melt grafting of maleic anhydride (MAH) onto poly (3-hydroxybutyrate-co-4-hydrox-ybutyrate)[P(3HB-co-4HB)]/polylactic acid (PLA) blends were carried out via reactive extrusion. The effects of the contents of MAH, initiator (BPO) on the graft ratio were studied. The effects of grafting modification on thermal properties, mechanical properties, fracture morphology and compatibility of P(3HB-co-4HB)/PLA blends were characterized by differential scanning calorimeter (DSC), electronic universal testing machine and scanning electron microscopy (SEM) etc. The results showed that the graft ratio of blends increased to a maximum and then decreased with increasing contents of MAH and BPO; The tensile strength, impact strength of blends were significantly improved, and the graft ratio achieved the maximum value at 1.0phr MAH and 0.3phr BPO; Through analysis from DSC and SEM, it indicated that the compatibility of P(3HB-co-4HB)/PLA blends was improved effectively.

Abstract: Nonlinear absorption of monolayer graphene and graphene oxide suspensions were studied in the wavelength of 800 nm by Z-scan method with 50fs pulses. Large reverse saturable absorption is observed in graphene, while graphene oxide shows saturable absorption at the incident intensity of 46 GW/cm². The values of nonlinear absorption coefficient also have been determined from the experimental data. The NLA coefficient β of the monolayer graphene suspension is 1.96×10^-2cm/GW,while the NLA coeffiecient β of graphene oxide is-6.84×10^-3cm/GW.

Abstract: Based on cellular automata, a model of simulating grain growth was established and the key technologies of simulation was studied which including second phase particle of single size, multi-size distribution and different shapes generation technologies. The simulation result can accurately reflect the influence law of the second phase particle grain growth and its pinning mechanism. Grain boundaries can therefore more easily break free from the particles than in purely two-dimensional systems, resulting in fewer grain boundaryparticle intersections and a larger final grain size. For a given volume fraction f and size of the particles r, the final grain size increases with film thickness. Moreover, it was found that particles located in the middle of the film are most efficient in pinning grain boundaries. The simulation results are compared with Zener type relations and previous simulation results.

Abstract: This paper presents a review of developing of creep damage constitutive equations for high chromium alloy (such as P91 alloy). Firstly, it briefly introduces the background of creep damage for P91 materials. Then, it summarizes the typical creep damage constitutive equations developed and applied for P91 alloy, and the main deficiencies of KRH (Kachanov-Robatnov-Hayhurst) type and Xus type constitutive equations. Finally it suggests the directions for future work. This paper contributes to the knowledge for the developing creep damage constitutive equations for the specific material.

Abstract: cosahedral quasicrystalline phase (I-phase) formed in a number of Ti-based alloys, and the I-phase is well ordered and thermodynamically stable in the alloys. Because Ti-based icosahedral (i) quasicrystal phases, which have a new type of translational long-range order and display noncrystallographic rotational symmetry, are believed to possess a large number of tetrahedral interstitial sites in their quasilattices. Ti-based I-phase alloy was considered as one of the most promising hydrogen storage materials due to thermodynamical stability, suitable chemistry affinity and low cost. Recent year, the Ti-based I-phase alloys containing crystal or amorphous phases were prepared, and microstructure and hydrogen storage characteristics were investigated. Ti-based I-phase alloy becomes one of the most promising hydrogen storage materials due to thermodynamical stability, low cost and high hydrogen capacity, and exhibited good electrochemical hydrogen storage capacity and cycle life property.