Advanced Materials Research Vols. 79-82

Abstract: A NiCr/Cr3C2 composite coating with a thickness of approximately 200 m was deposited onto 1Cr18Ni9Ti stainless steel substrate by high-velocity oxy-fuel (HVOF) thermal spraying. Microstructure of the coating was characterized using X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The coating comprised a NiCr matrix and two types of carbides. The NiCr matrix was composed of an amorphous phase and nanocrystalline grain with a size of 10–50 nm. The microhardness of the coating was found to be 1200Hv, which is significantly greater than that of the stainless steel (1Cr18Ni9Ti) substrate (285 Hv).

Abstract: In this work, the PCS/CS/HA composites with different weight ratios were prepared through a co-precipitation method. The properties of these composites were characterized by means of the XRD, the IR, the SEM and the bending strength test. The value of bending strength of the PCS/CS/ HA composite with a weight ratio of 10/30/60 was measured about 34.93 MPa which is 1.6 times high of the cancellous bone. The composite is appropriate to be used as materials for bone tissue engineering.

Abstract: Eu2Zr2O7 nanocrystals with cubic structure were successfully synthesized by salt-assistant combustion method. The Eu2Zr2O7 nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Emission/ excitation spectra. The effect of thermal treatment temperature on the crystal size of nanocrystals was studied. The results indicated that Eu2Zr2O7 nanocrystals obtained by this method were well-dispersed and uniform in particle size distribution with average size of 20 nm. By comparison, it was found that the introduction of KCl in the solution combustion reaction process can effectively prevent nanocrystallites from sintering and forming inseparable three-dimensional network, and result in the formation of well-dispersed nanoparticles. The method provides a convenient, low-cost and nontoxic route for the synthesis of nanostructures of oxide materials. Moreover, the strong fluorescent property of the Eu2Zr2O7 nanocrystals obtained by salt-assistant combustion method at 385 nm upon excitation was measured at room temperature. The results showed that Eu2Zr2O7 nanocrystals obtained by salt-assistant combustion method put up excellent fluorescent properties.

Abstract: An approach to chemical recycling of carbon fiber reinforced epoxy resin cured with amine has been investigated. Amine cured epoxy resin was decomposed totally when it was treated with nitric acid solution under certain conditions. The impacts of nitric acid concentration and decomposition temperature on recycling method were studied with decomposing time and the performance of carbon fiber as indexes. Epoxy resin matrix decomposed entirely after 23hrs at 95°C in the 8mol/L nitric acid solution. Scanning electron microscopy analysis (SEM) and monofilament strength were used to characterize the recycled carbon fibers.

Abstract: In this paper, A kind of ideal non-cyanide silver deposits was obtained by joining the ultrasonic. ultrasonic frequency of 28KHz, power increased from 0-500W, XRD tests show:with the increasing in electric power deposition, silver coating (111) and (200) crystal plane orientation significantly improved, and (220) crystal plane orientation declined . With the ultrasonic power increased, silver deposition current efficiency increased first and then reduced. the grain size refined with the ultrasonic increasing .the corrosion resistance decreased with the ultrasonic increasing.and SEM showed that the grain sizes decreased with the ultrasonic.

Abstract: Carbon nanotubes (CNTs) reinforced natural rubber (NR) composites with the CNT contents of 1, 3, 5, 10 and 20 wt% were synthesized using a solution casting method. The morphology of the composites was observed by scanning electron microscopy and Fourier transform infrared spectroscopy. It was found that CNTs were well distributed into NR and there was an excellent interface between CNTs and natural rubber. The mechanical properties of the composites were investigated by dynamic mechanical analysis (DMA) test and tensile test. It was found that the increment of storage modulus of NR/CNT composites was about 0.42 MPa/wt% in the rubbery state which agreed well with the results of tensile test. The large modulus increment confirmed the reinforcement effect of carbon nanotubes.

Abstract: Nanostructured flakes α-Ni(OH)2 microspheres were successfully synthesized by a facile solvothermal method using sodium dodecyl sulfate as a soft template and urea as a hydrolysis-controlling agent. The obtained products were characterized by Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties studies were carried out using cyclic voltammetry, galvanostaitc charge/discharge method, respectively. The results exhibited that the α-Ni(OH)2 single electrode had high specific capacitance in KOH electrolyte. A maximum specific capacitance of the α-Ni(OH)2 single electrode was up to 2398F/g in 6M KOH electrolyte concentration with 0 to 0.4V potential at 4mA/cm2 current density. Furthermore, the effects of the heat treatment temperatures on the electrochemical capacitance of the α-Ni(OH)2 electrodes were investigated.

Abstract: Novel semisolid casting technique allowing producing the cast composites with highly homogeneous structure is suggested. In according with this technique specially prepared metal bil-lets containing reinforcing nanoparticles are subjected to partial melting and compacting and fol-lowing solidifying. Some model systems were used in order to demonstrate the potential possibili-ties of this technique in principle.

Abstract: polyacrylate/nano-silicon dioxide nanocomposites were fabricated through a simple mixing process for resisting scratch and wear as coating. Chemical compatibility between polyacrylate matrix and nano-silicon dioxide (nano-SiO2) was achieved by functionalized nano-SiO2 via three silane coupling agents. Scanning electron microscopy (SEM) was done to characterize surface and wear morphology of the nanocomposites. Differential scanning calorimetry (DSC) was used for representing interfacial properties of the nanocomposites. A MM-200 machine and a Norman Tool RCA abrader were performed for testing friction and wear properties. SEM showed that incorporation of the nano-SiO2 functionalized with silane into the polyacrylate matrix showed a better dispersion than the composite without silane at low nanoparticle content (≤3 wt%). SEM also revealed that adhesive wear mechanism of the polyacrylate matrix was transited to dominated particle wear of the nanocomposites. An increase of glass transition temperature (Tg) was recorded via DSC at low nanoparticle content (1 wt%). Further addition of the nanoparticles to 3 wt% led to a 10°C increase in Tg comparing to neat polyacrylate. Results of friction and wear properties exhibited that friction coefficient and wear loss of the nanocomposites with silane were lower than those of the neat polyacrylate. The wear loss of the neat polyacrylate, the nanocomposite containing 3 wt% nanoparticles with silane KH570, and the nanocomposite with raw nano-particles were 108.6, 65.8, and 110.5mg, respectively. RCA results also showed a significant improvement of the nanocomposites in the presence of the nanoparticles with silane.

Abstract: In the present work, a novel titanate (H2Ti5O11•3H2O) nanotubes are synthesized by a simple hydrothermal method, and their thermal stability such as the phase transformations and microstructures change are also studied. The as-grown samples are heated in the air at 300-800 °C. The titanate nanotubes will be completely destroyed when the temperatures are above 600 °C, which show that the present titanate nanotubes possess good thermal stabilization. The experiment results reveal that the phase transformations and microstructure changes of present titanate nanotubes follow the process from titanate nanotubes to anatase and rutile TiO2 nanobelts, the Na2Ti6O13 nanwires are formed over 700 °C.