A Review of: “Interfacial Phenomena in Polymers,by Yuri S. Lipatov. Naukova Dumka Publ., Kiev, 1980, 259 pp. (in Russian).”

Bonding aluminum metal and its alloys with epoxy adhesives is sensitive to process variables, particularly surface contamination and moisture exposure. In the past, several surface modification schemes have been developed to improve the epoxy-bonding of aluminum. The present work describes a simple process that produces significant improvement in strength and durability of epoxy-bonded aluminum. In this process, aluminum surfaces are first rinsed with dilute sodium metasilicate solution followed by a dilute aqueous epoxysilane solution. The combination of the two materials exhibits a bond strength synergism as measured by bondline fracture toughness. The treated aluminum surface also exhibits a significant increase in bond strength tolerance to contamination and moisture exposure. The effect of epoxysilane chemical structure on bond durability was examined, as was the role of the silicate surface treatment.     

Comparative corrosive characteristics of petroleum diesel and palm biodiesel for automotive materials

Corrosive characteristics of biodiesel are important for long term durability of engine parts. The present study aims to compare the corrosion behavior of aluminum, copper and stainless steel in both petroleum diesel and palm biodiesel. Immersion tests in biodiesel (B100) and diesel (B0) were carried out at 80 °C for 1200 h. At the end of the test, corrosion characteristic was investigated by weight loss measurements and changes on the exposed metal surface. Surface morphology was examined by optical microscope and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS). Fuels were analyzed by using TAN analyzer, FTIR, GCMS and ICP in order to investigate the acid concentration, oxidation level with water content, compositional characteristics and presence of metal species respectively. Results show that the extent of corrosion and change in fuel properties upon exposure to metals are more in biodiesel than that in diesel. Copper and aluminum were susceptible to attack by biodiesel whereas stainless steel was not.     

High-strength AlN ceramics by low-temperature sintering with CaZrO3–Y2O3 co-additives

Aluminum nitride (AlN) ceramics with the concurrent addition of CaZrO₃ and Y₂O₃ were sintered at 1450-1700 °C. The degree of densification, microstructure, flexural strength, and thermal conductivity of the resulting ceramics were evaluated with respect to their composition and sintering temperature. Specimens prepared using both additives could be sintered to almost full density at relatively low temperature (3 h at 1550 °C under nitrogen at ambient pressure); grain growth was suppressed by grain-boundary pinning, and high flexural strength over 630 MPa could be obtained. With two-step sintering process, the morphology of second phase was changed from interconnected structure to isolated structure; this two-step process limited grain growth and increased thermal conductivity. The highest thermal conductivity (156 Wm⁻¹ K⁻¹) was achieved by two-step sintering, and the ceramic showed moderate flexural strength (560 MPa).     

时效温度和镁含量对高镁铝合金微观组织和腐蚀性能的影响

采用金相显微镜、电镜、DSC、晶间腐蚀、慢应变拉伸及阳极极化测试研究时效温度和Mg含量对固溶态高镁铝合金组织和腐蚀性能的影响。研究结果表明:淬火态的合金中β相生成很少,其孔蚀电位高,抗晶间腐蚀能力强,且应力腐蚀敏感性很低;经过150℃时效后的合金,晶体中析出了大量的β相,并且随着Mg含量的增加,β相的数目越多,其耐晶间腐蚀能力越弱,抗应力腐蚀能力也越弱;经过350℃时效后的合金,晶体中大部分β相已经被溶解,因此,与经过150℃时效的合金比较,其抗晶间腐蚀能力增加,抗应力腐蚀能力也增强。     

Ball-burnishing effect on deep residual stress on AISI 1038 and AA2017-T4

Ball-burnishing induces compressive residual stresses on treated materials by the effect of plastic deformation. The result is an increase in the fatigue life of the treated part, retarding the initiation of cracks on the surface. Compressive residual stresses have been previously measured by X-ray diffraction near the surface, revealing considerably high values at the maximum analyzed depth, in relation to other finishing processes such as shot peening. However, the maximum analyzed depth is very limited by using this technique. In this paper, the incremental hole drilling (IHD) technique is tested to measure residual stresses, being able to reach a 2-mm measuring depth. To that objective, a commercial strain gage is used and calibrated using finite element model simulations. A second Finite Element Model based on material removal rate is developed to obtain the equations to calculate the strain release through IHD. Finally, residual stresses are measured experimentally with that technique on two different materials, confirming that ball-burnishing increases the compressive residual stresses in layers up to 0.5?mm deep for the testing conditions, which is a good response to industrial needs. The method proves to be suitable, simple and inexpensive way to measure the value of these tensions.     

大型铝合金铸件（轮圈）的半固态成形技术

半固态金属的组织及流变特性,早在1971年就被美国麻省理工学院（MIT）的Flemings教授所指导的研究团队,在进行实验时偶然间所发现。但半固态铝合金商业应用的产品,除了美国AEMP及瑞士Buhler公司分别拥有及发表铝轮圈的半固态成形技术之外,大部分仍停留在中小型铸件的生产。为了适应汽车轻量化需求,由作者的服务单位与（台湾）工业技术研究院所合组的研究团队,在历经约三年的合作,从半固态触变铸造（Thixocasting）的球化坯料（slug）、再加热技术至流变铸造（Rheocasting）的半固态浆料（Slurry）,进行了多项实验,最终验证了半固态技术应用于大型铝合金铸件（轮囤）生产的可行性。自2005年起,使用A356合金材料改良流变铸造法及2700t的实时射控压铸机的生产线,成功产出汽车用大尺寸半固态铝轮圈,并获得较传统铸造为佳的力学性能,有效达成零部件轻量化需求。     

Characterization of black rust staining of unpassivated 55% Al–Zn alloy coatings. Effect of temperature, pH and wet storage

Wet storage staining is a phenomenon that occurs on both zinc coated and 55% Al–Zn coated steel sheets during shipment or storage in damp conditions. Whereas zinc coated sheets form white corrosion products, 55% Al–Zn coated steel sheets form black corrosion products. The effect of temperature, pH and wet storage on the occurrence of black rust staining of unpassivated Aluzink samples has been investigated in the laboratory in terms of corrosion product formation and composition. A characterization of corrosion products formed has been performed mainly based on scanning electron microscopy with X-ray microanalyses (SEM/EDS) for morphological and quantitative analyses and X-ray diffraction techniques (XRD) for crystalline phase identification. Black rust formation is strongly related to alkaline pH regions and is enhanced by the temperature. All black panels show the presence of Bayerite (Al(OH)₃), mainly formed on the aluminum rich dendrite branches and a basic zinc aluminum carbonate (Zn₆Al₂(OH)₁₆CO₃·4H₂O) formed in the zinc rich interdendritic alloy regions in contact with air. Blackening of Aluzink surfaces is connected to differences in optical properties of embedded metallic zinc and/or aluminum particles of different shape and size in the corrosion layer.     

铝合金液压阀岛的研究及性能分析

本文介绍了铝合金液压阀岛开发的关键技术及解决措施,并对铝合金液压阀岛的性能进行了分析,给出了试验结果。     

Combining Aluminum Heat Treat with Hot Isostatic Pressing： A Comparison of Structure, Properties, and Processing Routes for a Cast Al-Si-Mg Alloy

Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal^R, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing.This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.