Ce对Sn-58Bi合金组织与性能的影响

采用真空熔炼方法制备了不同Ce含量的Sn?58Bi合金,对其显微组织、熔化特性和润湿性等进行了分析,重点研究了稀土Ce对Sn?58Bi与Cu基板焊点剪切强度的影响. 结果表明,Ce能细化Sn?58Bi合金的共晶组织,而对合金的熔点、熔程影响较小. Ce添加量增加,合金的润湿性降低,Ce添加量为0.1wt%时,Sn?58Bi/Cu焊点剪切强度最佳,达15 MPa.     

无铅铋玻璃的制备及性能研究

采用熔融急冷法制备了含有Bi2O2的低熔点硼硅酸盐玻璃,确定了成玻性能、转变温度(T)和热膨胀系数,通过XRD、DTA及热膨胀仪确定了该系统易熔封接玻璃的玻璃化范围,以及玻璃的转变温度和玻璃的热膨胀系数与玻璃组成的关系.     

The Design of Double-Overlap Joints Using Thermoplastic-Fibre Composites

The present paper considers the adhesive bonding of thermoplastic fibre-composites using an epoxy-paste adhesive. The joint design used for these studies is a double-overlap geometry. Firstly, it is shown that to obtain good joint strengths the thermoplastic fibre-composite substrates need to be subjected to a corona surface treatment prior to bonding. Secondly, it is established that the use of tapered composite substrates and angled adhesive-fillets can substantially increase the joint strength. Indeed, the joint efficiency can approach 100% for such designs of double-overlap joints. Thirdly, finite-element analyses have been employed to study theoretically the various designs of joints, and the results from such analyses are in good agreement with the experimental measurements.     

新型的低温无铅釉

介绍了一种新型的低温无铅釉。这种釉主要有二氧化硅、氧化锌和硅酸钠调制而成。它不仅可在500-1000℃低温下烧成,降低燃料消耗及其费用,而且具有良好的耐水性和耐酸性,除用于陶瓷制品外,还适用于金属、水泥、硅酸钙材质的建材制品。     

Structural and Dielectric Properties of Lead-Free Zr-Doped Barium Titanates

Lead-free BaZr _x Ti_1–xO₃ ferroelectrics (x = 0.2, 0.4, 0.6, 0.8) were synthesized by conventional double-sintering technique. The structural, morphological, and dielectric properties of BaZr _x Ti_1–xO₃ were investigated as a function of zirconium content x. A single-phase perovskite structure of tetragonal ceramics was identified by XRD. The SEM images of the ferroelectrics exhibit fine grains of varied porosity. All synthesized samples exhibited dielectric dispersion at low frequencies.     

无铅磷酸盐封接玻璃的最新进展

分析了传统铅基封接玻璃对环境的影响，综述了无铅磷酸盐封接玻璃的特点、组成和制备、基本结构与性能及其研究方法，讨论了组成对结构和性能的影响。指出当前研究存在的问题，对这类新型封接玻璃的应用前景进行了预测。     

Hygrothermal Properties of Adhesively Bonded Joints and Their Correlation with Bulk Adhesive Properties

The combined effects of heat (50[ddot]C) and humidity (95% R.H.) on the lap shear and T-peel strengths of 120[ddot]C, 150[ddot]C and 215[ddot]C service epoxy film adhesives have been characterized. Experimental results have indicated that effects of hygrothermal conditioning on lap shear and peel properties vary with exposure time and final testing temperatures and type of adhesive tested. In the cases where cohesive failure was observed in the shear and peel specimens, a correlation could be established between the bulk properties of the adhesives (tensile strength and elongation) and their adhesively bonded joint properties (shear and peel). When testing was carried out at room temperature, a general correlation between the tensile elongation and T-peel or shear could be obtained. At below freezing temperatures, lap shear strength seemed to be correlated with bulk tensile strength while peel correlated with bulk tensile elongation. At elevated temperatures, the relative contributions of bulk strength and elongation were the decisive factors as far as shear and peel strengths are concerned.     

Mechanism of the interfacial reaction between sapphire and Sn-3.5Ag-4Ti solder at a low temperature in air by ultrasound

The joining of sapphire at a low temperature is necessary for the packaging of temperature-sensitive components. In current processes, the sapphire was bonded to Sn-based Ti-activated solders by mechanical scraping and stirring. To improve the efficiency and the bonding strength, the joining of sapphire by ultrasonic-assisted hot dipping and soldering at 250 °C in air was investigated. The relationship between the interfacial structure and shear strength of the soldered joints was revealed. The joints dipped for different durations and soldered for 0.5 s had similar interface morphologies, while the shear strength of the joints was controlled by the dipping duration. The shear strength of the joints dipped for 100 s reached 33 MPa. An uneven reaction layer of Ti oxides was found at the interface by TEM and EDS. A physical model was established to explain the formation of the reaction layer and the evolution of the interface microstructure. The mechanism of the interfacial reaction was discussed based on thermodynamics. The results of the thermodynamic calculations show that the replacement reaction between Ti and sapphire could not occur at the joining temperature of 250 °C. The increasing temperature induced by ultrasound at the liquid/solid interface was calculated by bubble dynamics and thermal conduction methods. It could be inferred that the reaction may be dominated by a local high temperature at the interface. Our finding demonstrates that the ultrasonic effects promote and facilitate the interfacial reaction of sapphire and Sn-3.5Ag-4Ti.     

Influence of CuO on the Structure and Piezoelectric Properties of the Alkaline Niobate-Based Lead-Free Ceramics

Recently, it was reported that the alkaline niobate-based (K,Na,Li)(Nb,Ta,Sb)O₃ (LF4) perovskite ceramics showed excellent piezoelectric properties and have been regarded as a new candidate of lead-free piezoelectric materials. However, the effects of additives on the piezoelectric property of LF4 have not been studied intensively so far. In this study, the effect of CuO addition to the LF4 was investigated. The sample showed a tetragonal phase at room temperature and also a second phase with low melt point. With 0.05 wt% CuO added, the Cu²⁺ firstly incorporated into the A site, while higher amounts of Cu²⁺ substituted B-site ions. The CuO-doping changed the LF4 to "hard" piezoelectric ceramics with improvement of mechanical quality factor from 26 to 137 but the piezoelectric d ₃₁ constant and the electromechanical coupling constant reduced drastically at the same time.     

350万t/a重油催化裂化装置的设计与标定

介绍了国内某新建千万吨级大型炼厂350万t/a重油催化裂化装置设计及开工运行情况.装置采用美国UOP公司的RFCC工艺包,加工加氢裂化尾油、减压蜡油和减压渣油的混合原料.主要介绍了主要技术特点、开工运行及标定情况.     

浅谈胶条接头与模具设计

简要地介绍了橡胶条常见接头工艺方法、应用特点及模具结构与设计方法。     

Stress Analysis and Failure Properties of Carbon-Fibre-Reinforced-Plastic/Steel Double-Lap Joints

The present paper considers the strength of CFRP/steel double-lap joints loaded in tension. A detailed stress analysis has been conducted of the shear and transverse tensile stresses in the joint, using an elastic-plastic model for the rubber-modified epoxy adhesive. The results of this analysis have been combined with the measured properties of the materials forming the joint in order to predict quantitatively the failure strengths of the various joint designs studied. There was good agreement between the theoretically predicted and experimentally measured strengths. These studies have led to a highly efficient design being developed.     

Evaluation of Brazed Silicon Nitride Joints: Microstructure and Mechanical Properties

Sintered Si₃N₄ has been bonded to itself and to AISI 316 steel by the active-metal brazing route. A commercial Ag-35Cu-1.6Ti filler has been used with joining taking place during a 30 min hold at 850°C under vacuum. Si₃N₄/ Si₃N₄ joints have been produced with strength distribution (average bend strength = 773.5 MPa, Weibull modulus = 11.2) similar to that of the monolithic ceramic. Direct brazing of the Si₃N₄ to AISI 316 steel was unsuccessful. However, reliably strong (bend strength of 250–400 MPa) ceramic/ steel joints with 20 × 20 mm² cross sections were fabricated by using Cu, Mo, or Nb interlayers. The most potent inter-layer used in this work was Mo, whose coefficient of thermal expansion matches best that of the ceramic.     

The Efficient Design of Adhesive Bonded Joints

A concise method of analysis is used to study the numerous parameters influencing the stress distribution within the adhesive of a single lap joint. The formulation includes transverse shear and normal strain deformations. Both isotropic or anisotropic material systems of similar or dissimilar adherends are analysed. Results indicate that the primary Young's modulus of the adherend, the overlap length, and the adhesive's material properties are the parameters most influential in optimizing the design of a single lap joint.     

The Efficient Design of Adhesive Bonded Joints

A concise method of analysis is used to study the numerous parameters influencing the stress distribution within the adhesive of a single lap joint. The formulation includes transverse shear and normal strain deformations. Both isotropic or anisotropic material systems of similar or dissimilar adherends are analysed. Results indicate that the primary Young's modulus of the adherend, the overlap length, and the adhesive's material properties are the parameters most influential in optimizing the design of a single lap joint.     

Strength Improvement of Adhesively-Bonded Joints Using a Reverse-Bent Geometry

Adhesive bonding of components has become more efficient in recent years due to the developments in adhesive technology, which has resulted in higher peel and shear strengths, and also in allowable ductility up to failure. As a result, fastening and riveting methods are being progressively replaced by adhesive bonding, allowing a big step towards stronger and lighter unions. However, single-lap bonded joints still generate substantial peel and shear stress concentrations at the overlap edges that can be harmful to the structure, especially when using brittle adhesives that do not allow plasticization in these regions. In this work, a numerical and experimental study is performed to evaluate the feasibility of bending the adherends at the ends of the overlap for the strength improvement of single-lap aluminium joints bonded with a brittle and a ductile adhesive. Different combinations of joint eccentricity were tested, including absence of eccentricity, allowing the optimization of the joint. A Finite Element stress and failure analysis in ABAQUS^® was also carried out to provide a better understanding of the bent configuration. Results showed a major advantage of using the proposed modification for the brittle adhesive, but the joints with the ductile adhesive were not much affected by the bending technique.     

无铅玻璃的发展与应用

简要阐述了铅污染的危害性,从日用玻璃和电子玻璃2方面论述世界针对铅污染的政策、法规。并指出了我国在日用玻璃和电子玻璃2方面的发展状况,进而着重讲述目前国内外在无铅玻璃方面采取的措施、进展和发展趋势。     

Mechanical Properties of Weldbonded Joints of Advanced High Strength Steels

In lightweight car body shell mass production, due to requirements on vehicle weight reduction and carbon dioxide emissions, joining of advanced high strength steels (AHSS) with different joining procedures and especially hybrid bonding techniques is becoming more and more important. One of these hybrid bonding techniques is the combination of resistance spot welding and adhesive bonding called weldbonding. One of the important advantages of weldbonded joints in comparison to resistance spot welded joints are the enhanced mechanical properties. To guarantee sufficiently high quality conditions regarding the strength of the weldbonded joints, the influences of the applied adhesive systems and of different base metal combinations are studied. This is carried out for both non-corrosive and corrosive environments and for the choice of different joining parameters settings. In particular, the mechanical behaviour of the weldbonded joints is investigated under quasi-static, impact and fatigue loads. Furthermore, the energy absorption of the weldbonded joints for both non-corrosive and corrosive environments is studied. It is shown that the weldbonded joints possess higher mechanical strengths in all load cases (quasi-static, impact and fatigue). Corrosive attack affects weldbonded joints, and the quasi-static strength is reduced. Resistance spot welded joints are not affected by the corrosive attack, but even after several weeks of corrosive attack, the quasi-static strength of weldbonded joints remains higher than that of resistance spot welded joints.     

Measurement of Mode I and Mode II Fracture Properties of Wood-Bonded Joints

In this work, the fracture characterisation of wood-bonded joints under pure mode I and mode II loading was performed. The tested material was maritime pine (Pinus pinaster Ait.) bonded with an epoxy adhesive. Two fracture mechanical tests were chosen: the double cantilever beam (DCB) for opening mode I loading, and the end-notched flexure (ENF) for sliding mode II loading. The compliance-based beam method (CBBM) was used for both mode I and mode II fracture, since the Resistance-curves can be obtained directly from the global mechanical response of the specimens (load–displacement curve), without crack monitoring during propagation. This data reduction scheme was validated by direct comparison with the modified experimental compliance method (MECM).