纳米级SiCp/6066Al复合材料的制备与力学性能的研究

采用粉末冶金方法制备了纳米SiCp增强铝基复合材料，研究了增强相尺寸对铝基复合材料性能的影响。结果表明：体积分数为1％的纳米级SiCp／6066Al复合材料的强度与体积分数为12％、尺寸为7μm的SiCp／6066Al复合材料的强度相当，并且前者的塑性高于后者。     

Joining of SiO2 ceramic and TC4 alloy by nanoparticles modified brazing filler metal

Nano-Al₂O₃ particles modified AgCuNi filler was adopted to braze the SiO₂ ceramic and TC4. The effects of filler size as well as the brazing temperature on the interfacial microstructure and mechanical property of the joints were investigated. Nanoscale filler reduced the phases dimension and promoted the homogeneous distribution of microstructure, obtaining a higher joint strength when compared to microscale filler. The increase of brazing temperature made the accelerating dissolution and diffusion of Ti, which promoted the increase of thickness of Ti₄O₇ + TiSi₂ layer adjacent to SiO₂ ceramic and diffusion layer zone nearby TC4 alloy. The hypoeutectic structure was produced in the brazing seam due to the high Ti content. The maximum shear strength of ∼40 MPa was obtained at 950 °C for 10 min.     

Nanoparticle type effects on flexural,interfacial and vibration properties of GFRE composites

Damping improvement in composite structures via introducing nanofillers generally has remarkable negative effects on the other mechanical properties. Therefore, in the present work, Si C and Al_2O_3 nanoparticles' infusion effects on the flexural, interfacial and vibration properties of epoxy matrix and glass fiber reinforced epoxy(GFR/E) laminates were investigated. Unidirectional(UD-GFR/E) and quasi-isotropic(QI-GFR/E) laminates with [0/±45/90]sand [90/±45/0]sstacking sequences were hybridized by the optimum nanoparticles percentages. Results from off-axis flexural strengths of UD-GFR/E demonstrate good fiber/nanophased-matrix interfacial bonding.The interlaminar shear stress between the adjacent layers with different orientations/strains of ductile QI-GFR/Si C/E laminates results in decreasing the flexural strengths respectively by 24.3% and9.1% for [0/±45/90]sand [90/±45/0]sstacking sequences and increasing the dissipated interfacial friction energy and thus the damping by 105.7% and 26.1%. The damping of QI-GFR/E,QI-GFR/Si C/E and QI-GFR/Al_2O_3/E laminates with [90/±45/0]sstacking sequence was increased by 111.4%, 29.7% and 32.9% respectively compared to [0/±45/90]sstacking sequence.     

Radiation efects on MHD stagnation point flow of nano fluid towards a stretching surface with convective boundary condition

The aim of the present paper is to study the numerical solutions of the steady MHD two dimensional stagnation point flow of an incompressible nano fluid towards a stretching cylinder.The effects of radiation and convective boundary condition are also taken into account.The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis.The resulting nonlinear momentum,energy and nano particle equations are simplifed using similarity transformations.Numerical solutions have been obtained for the velocity,temperature and nanoparticle fraction profles.The influence of physical parameters on the velocity,temperature,nanoparticle fraction,rates of heat transfer and nanoparticle fraction are shown graphically.