Advanced Materials Research Vols. 1120-1121

Abstract: In this paper, Kevlar or Polysulfonamide (PSA) pulp were used to replace plant fiber pulp partially or completely and by adjusting their ratios and a variety of Kevlar or PSA pulp reinforced activated carbon fiber paper (ACFP) were prepared via wet-laid paper making technology. The influences of addition of Kevlar or PSA pulp on the permeability, mechanical property, filtration performance, adsorption property of ACFP were discussed by maintaining the addition content of activated carbon fiber unchanged. Results showed that with the addition content of Kevlar or PSA pulp increased, the permeability and filtration performance of ACFP decreased obviously, while the bursting strength and the static CCl₄ adsorption performances were firstly increased and then decreased. Generally, the permeability and filtration performance of Kevlar pulp reinforced ACFP were slightly worse than that of PSA pulp reinforced ACFP, while the bursting strength as well as the static CCl₄ adsorption properties of Kevlar pulp reinforced ACFP were better than that of PSA pulp reinforced ACFP.

Abstract: through the use of domestic carbon fiber cloth and combining domestic fast-growing wood of Larch and poplar wood, the CFRP- wood composite key interface from the composite process, stripping bearing performance, Hygrothermal effect, fracture characteristics and shear creep properties to conducted the system research . Fiber reinforced composite (Fiber Reinforced Plastic/Polymer, abbreviation FRP) material by continuous fibers and resin matrix composite and its types, including carbon fiber reinforced composite (Carbon Fiber Reinforce Plastic/Polymer, abbreviation CFRP), glass fiber reinforced composite (Glass Fiber Reinforced Plastic/Polymer, abbreviation GFRP) and aramid fiber reinforced composite (Aramid Fiber Reinforced Plastic/Polymer, abbreviation AFRP). PAN based carbon fiber sheet by former PAN wires, PAN raw silk production high technical requirements, its technical difficulty is mainly manifested in the acrylonitrile spinning technique, PAN precursor, acrylonitrile polymerization process with solvent and initiator ratio. Based on this consideration, the subject chosen by domestic PAN precursor as the basic unit of the CFRP as the object of study.

Abstract: PcBN–Al composites（PAC）have been synthesized by pressure infiltration(PI) and a general mixing method(GM)[1-3] with a wide grain sizes range of 4-25 um and a wide temperature range of 1200-1600°C at 5.0 GPa,respectively.Hardness ranged between 30and 40 GPa, while the flank wear (Vb) reached 0.12mm when it finished 4000m in cutting test ofPAC synthesized by PI method. Hardness ranged between 25 and 35GPa, while the flank wear (Vb) reached 0.14 mm when it finished 4000mof PAC synthesized by GM method. The homogeneity of PcBN–Al synthesized by PI have been improved compared with GM. PI is a superior method to synthesize PAC in the field of mechanical properties.

Abstract: The aim of this work is to define a general method for the optimization of composite patch repairing. Fracture mechanics theory shows that the stress intensity factor tends towards an asymptotic limit K_∞. This limit is given by Rose’s formula and is a function of the thicknesses and mechanical properties of the cracked plate, the composite patch and the adhesive. The proposed approach consists in considering this limit as an objective function that needs to be minimized. In deed lowering this asymptote will reduce the values of the stress intensity factor hence optimize the repair. However to be effective this robust design must satisfy the stiffness ratio criteria. The resolution of this double objective optimization problem with Matlab program allowed us determine the appropriate geometric and mechanical properties that allow the optimum design; that is the selection of the adhesive, the patch and their respective thicknesses.

Abstract: In the present study, a surface pretreatment method consisting of KOH etching followed by oxide thickening in boiling water was used to improve the corrosion and adhesion resistance of the coating. The coating morphology on non-pretreated and pretreated Al substrates was characterized by means of scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle measurement. FT-IR spectra was obtained by Fourier transform infrared spectrometer. The corrosion resistance of the coating in 3.5 wt.% NaCl solution was evaluated with potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The adhesion resistance of the coating was tested using ISO-2409 standard. Results show that KOH etching followed by oxide thickening in boiling water can effectively improves the corrosion resistance and durability of the coating. Besides, this surface pretreatment method can also improve significantly the adhesion resistance of the coating.

Abstract: The NiCrAlY-ZrO₂ anti-ablation compound coating was prepared on one surface of a 201stainless steel by plasma spraying, and the ablation property was studied by the cyclic ablation experiment. The morphology and XRD pattern of the NiCrAlY-ZrO₂ coating were characterized by SEM and XRD methods before and after ablation on the high-temperature oxyacetylene flame. The results show a good adhesion between the coating and substrate. After the ablation at high temperature flame, the smoothness of the coating surface declined. The coating, under the oxyacetylene flame of 2800°C, can effectively improve the anti-ablation property of the substrate material, the mass loss for the coated sample is 1/4 of the uncoated specimen under the same number of ablation cycles.

Abstract: The experiment of laser cladding on the surface of 20 steel was made. The mixed powder of cobalt-based alloy powder (Co55) and tungsten powder was used as cladding material. There were three kinds of weight percent of tungsten powder, 5%, 10% and 15%. The microstructure and hardness of three kinds of laser cladding layer were studied. The microstructure of cladding zone was greatly refined after adding tungsten powder to Co55 powder. When the proportion of tungsten powder was 5%, the cladding zone was made up of dendritic crystal. The average hardness of cladding zone was 590 HV0.2. When the proportion of tungsten powder rose to 10%, there was reticular secondary carbide precipitating along the grain boundary. The average hardness of cladding zone was 648 HV0.2. When the proportion of tungsten powder rose to 15%, much granular carbide would diffusely distribute in Ni-based solid solution. The average hardness of cladding zone was 831 HV0.2.

Abstract: The experiment of laser cladding on the surface of Cr12 mold steel was made. Ni-coated nano-Al₂O₃ particles powder was used as cladding material. The microstructure and hardness of laser cladding layer were tested. The research showed that the compact cladding layer without crack, gas hole and other defects could be made by laser cladding. The cladding layer was made up of three phases, Fe-Ni solid solution, Fe-Cr solid solution and nano-Al₂O₃ particle. nano-Al₂O₃ particles enhanced the inhomogeneous nucleation of Fe-based alloy, refined the crystal grains and strengthened the mechanical properties of cladding layer. The average hardness of cladding zone was 900 HV0.2 which was 2.2 times higher than that of substrate.

Abstract: The Ni/WC/G composite coating was fabricated through vacuum cladding. The effect of graphite content on the wear behavior was investigated, and the worn surface was observed through scanning electron microscopy (SEM). The friction coefficient decreased with the increasing graphite content until the graphite content was 6%, and then increased when the graphite content was 8%. The wear rate decreased with the increasing graphite content for all graphite content. The wear loss of GCr15plate decreased with the increasing graphite content until the graphite content was 6%, and the wear loss of plate was rising when graphite was 8%. There was a layer composed of wear debris that containing oxides and graphite. The covering area increased with the increasing graphite content, which agreed with the changing trend of friction coefficient and wear rate. The net texture-like structure was formed among the composite coating, which could be the main support for load during wear process. There was little single WC particle protruding for support the wear load. Therefore, the Ni-based substrate was not easily to be worn.

Abstract: The composite coating that consisted of 50%(Ni-22%Cr-10%Al-1%Y) and 50%(ZrO₂-8%Y₂O₃) was fabricated by air plasma spraying, and corroded at 800 and 900°C for 50 h in Na₂SO₄ or 75%NaCl-25%Na₂SO₄ salt. The scales consisted primarily of Cr₂O₃, NiO and α-Al₂O₃. However, most of them continuously dissolved off as complex ions into the salt during hot corrosion.