CeO2含量对SiO2-B2O3-ZnO-K2O-BaO系彩釉玻璃基料性能的影响

采用熔融法制备了SiO 2-B 2O 3-ZnO-K 2O-BaO系彩釉玻璃基料,利用XRD、SEM、综合热分析、高温润湿角测量等手段研究了CeO 2添加量对玻璃基料相组成、显微形貌、热膨胀系数、特征温度和与钠钙玻璃的润湿性的影响。研究结果表明:当CeO 2的添加量高于3%(质量分数,下同)时,水淬后的玻璃基料样品在700℃进行钢化处理后,样品中会有CeO 2晶体析出。随着玻璃基料中CeO 2添加量的增加,样品的耐酸性、与钠钙玻璃润湿性和抗弯强度都先增强后降低。当CeO 2的添加量为1%时,样品与钠钙玻璃的润湿性最好,其润湿角取到最小值45.6°;当CeO 2的添加量为3%时,样品在5%(质量分数)的稀硫酸溶液中失重率取到最小值2.83 mg/cm 2,玻璃的耐酸性最好;当CeO 2的添加量为4%时,样品的抗弯强度最大,为75.69 MPa。结果表明,加入2%CeO 2的基料综合性能最优,具有良好的应用前景。

Damping properties and mechanism of aluminum matrix composites reinforced with glass cenospheres

The damping properties were improved by preparing Al matrix composites reinforced with glass cenospheres through the pressure infiltration method.Transmission electron microscopy and scanning electron microscopy were employed to characterize the microstructure of the composites.The low-frequency damping properties were examined by using a dynamic mechanical thermal analyzer,aiming at exploring the changing trend of damping capacity with strain,temperature,and frequency.The findings demonstrated that the damping value rose as temperature and strain increased,with a maximum value of 0.15.Additionally,the damping value decreased when the frequency increased.Dislocation damping under strain and interfacial damping under temperature served as the two primary damping mechanisms.The increase in the density of dislocation strong pinning points following heat treatment reduced the damping value,which was attributed to the heat treatment enhancement of the interfacial bonding force of the composites.

RELAXATION BEHAVIOUR OF GFRP UNIDIRECTIONAL LAMINATES

In this paper two set of GFRP specimens are manufactured and tested to investigate the relaxation behaviour under cyclic loading in the longitudinal and transversel direction. The relaxation of GFRP unidirectional laminates is evident for both cyclic loadings. Under longitudinal cyclic loading the relaxation is dependent on the number of loading cycles. Under transverse loading the relaxation depends on the loading cycles as well as the time of loading. Two expressions are set up to describe the relaxation for the longitudinal and transverse loading, and the predictions agree well with the experimental data.

Effects of infiltration parameters on mechanical and microstructural properties of tungsten wire reinforced Cu_(47)Ti_(33)Zr_(11)Ni_6Sn_2Si_1 metallic glass matrix composites

Cu47Ti33Zr11Ni6Sn2Si1-based bulk metallic glass matrix composites reinforced with tungsten wires were fabricated by infiltration process at different temperatures （850, 900, 950 and 1000 °C） and time （10, 20 and 30 min） in a quartz or a steel tube. The mechanical tests were carried out by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the maximum strength and total strain of the composite are 1778 MPa and 2.8% fabricated in steel tube at 900 °C for 10 min, and 1582 MPa and 3.6% fabricated in quartz tube at 850 °C for 10 min, respectively.

Characteristics of Cyanate Ester and Fluorenyl Epoxy-Based Polymer-Ceramic Composites

In the field of highly integrated printed circuit board （PCB）, the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate material with low moisture absorption and high glass transition temperature （Tg） simultaneously, a fluorenyl ＂Cardo＂ epoxy was incorporated into novolac cyanate ester resin. As an optimum curing agent for the fiuorenyl epoxy, methyl nadic anhydride （MNA） was selected. Silica powders as fillers were added into the resin composition. The partial replacement of the cyanate ester resin with the fluorenyl epoxy could reduce the moisture absorption with keeping high glass transition temperature over 300 ℃. The laminate, which was fabricated from prepregs made with 40 wt% silica-filled resin composition and glass fabric, showed high Tg of 317 ℃ and low moisture absorption of 0.57%.

Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium. It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around CulTMo20Hf63 and Cu34Mo57Hf9, respectively. Interestingly, at the nearly equal-atomic stoichiometry of Cu38Mo31Hf3i, a dual-phase Cu-Mo-Hf metallic glass, consisting both of the Mo-Hf-based and Cu-Mo-based phases, was first obtained at relatively low irradiation doses ranging from （1-5）×10^15 Xe＋/cm2, and a single-phase metallic glass was eventually obtained at a dose of 7×10^15 Xe＋/cm2. In addition, two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9, and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses, dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions, respectively. The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.