7075铝合金半固态浆料制备及流变压铸工艺研究

目的研究搅拌速度和搅拌时间对ACSR工艺制备的7075铝合金半固态浆料组织的影响,研究和比较传统压铸与流变压铸7075铝合金的组织与性能。方法通过改变搅拌速度和搅拌时间制备7075铝合金半固态浆料,取料水淬获得半固态坯料,将剩余浆料进行流变压铸,采用金相显微镜、扫描电子显微镜、万能试验机等研究了试样的微观组织、拉伸性能与断口形貌,探究搅拌速度和搅拌时间对7075合金半固态浆料组织的影响,同时研究与比较传统压铸与流变压铸7075铝合金的组织性能。结果在一定范围内提高搅拌速度和搅拌时间有利于α1-Al的细化与球化,与传统压铸7075铝合金相比,流变压铸合金具有更优异的力学性能,T6热处理后,其抗拉强度、屈服强度和伸长率分别为547 MPa、494 MPa和3.2%。结论 ACSR工艺可制备出组织细小圆整的7075铝合金半固态浆料,且流变压铸可改善7075铝合金力学性能。     

蛇形通道制备半固态浆料均热后的流变压铸

为了研究蛇形通道制备半固态浆料并经过均热后的流变压铸性能,以A356铝合金为材料进行实验研究.结果表明:当浇注温度为680℃、均热功率为1.6～2.5 kW时,半固态浆料的微观组织可以达到均一,而且初生α(Al)的形貌更加圆整;该浆料经过流变压铸成形后,在铸态下拉伸试样的抗拉强度可达245～260 MPa,伸长率可达8.5%～13%;经过T6热处理后,拉伸试样的抗拉强度可达295～320 MPa,伸长率可达7%～11%.均热可以对浆料的整个温度进行调整来满足不同铸件的流变压铸.     

大体积流变浆料制备与压铸成形一体化工艺及其应用

目的研究气体流量对ACSR流变压铸Al-Si-Fe合金组织的影响,同时研究与对比流变压铸与传统压铸合金的组织性能。方法通过改变气体流量制备流变压铸Al-Si-Fe合金,采用光学显微镜、扫描电子显微镜、电子探针、万能试验机等研究了合金的微观组织与拉伸性能。结果随着气体流量由0提高至6 L/s,流变压铸合金中α1-Al平均尺寸由35.6μm下降到23.9μm,形状因子由0.71上升到0.82;与传统压铸合金相比,流变压铸合金的抗拉强度和伸长率分别提高了15%和75%。结论 ACSR流变压铸工艺可以制备出组织细小圆整且力学性能高的铸件。     

双螺杆机械搅拌半固态镁合金的组织与性能

采用双螺杆机械搅拌制浆机和半固态流变压铸成形工艺制备AZ91D镁合金半固态浆料，研究了材料性能与微观组织之间的关系．结果表明，随着镁液的浇注温度或搅拌机简体温度的降低，半固态浆料的固相率越高，初生α-Mg相晶粒变得更细小和圆整，简体温度比镁液浇注温度的影响更显著．当浆料固相率控制在30％-45％时，半固态流变压铸成形镁合金铸件具有较高的抗拉强度和延伸率；随着晶粒平均尺寸的增加，材料的力学性能逐渐降低．提出了高剪切速率下流变压铸成形非枝晶组织的形成机理．     

ZL201合金半固态压铸成形过程数值模拟

为了解半固态压铸过程中浆料充型规律及其流动特点，本文采用AnyCasting铸造仿真软件特有的半固态触变功能模块(Bingham粘度模型)对半固态ZL201铝合金的触变充型过程进行数值模拟，研究慢、快压射速度及切换时间对半固态触变压铸充型过程的影响，对最优充型条件下的铸件微观组织及力学性能进行模拟研究，并进行试验对比.数值模拟结果显示，ZL201合金半固态触变压铸成形在浆料温度600 ℃、模具温度240 ℃时、低速压射速度0.1 m/s、且在1.5 s后进行速度切换、高速压射速度为1 m/s时，所得铸件维氏硬度最大可达72HV，平均抗拉强度为208 MPa.按照该工艺条件成型的成形件显微组织致密，测得其平均抗拉强度为212.5 MPa、平均硬度值为70.8HV, 性能较高，与模拟结果符合较好.     

ZL201合金的半固态成形组织和力学性能

制备ZL201合金半固态坯料、将其二次加热、触变模锻成形以及成形件热处理,研究了工艺条件对成形件的组织和力学性能的影响.结果表明:采用近液相线半连续铸造技术制备的ZL201合金半固态坯料微观组织为大量细小的等轴晶和少量短程枝晶;在适当的工艺条件(在640℃保温5 min,模具温度250～300℃,留模时间10～15 s)下可触变成形出表面光洁的ZL201合金成形件;经过T5处理后,ZL201合金的抗拉强度达到278 MPa,延伸率达到9%,大大高于压铸成形件的性能,其强化相为CuAl2和TiAl3.由于成形速度高,溶体高速充型,造成成形件气孔率高,使ZL201合金半固态压铸成形的组织致密度不如半固态模锻成形件,这是半固态压铸件强度低、模锻件强度高的主要原因.     

半固态A356铝合金浆料的充填行为及组织分布

采用流变压铸方法研究了低过热度浇注和弱电磁搅拌制备的半固态A356铝合金浆料的充填行为和组织分布，结果表明：采用该技术制备的半固态A356铝合金浆料，其组织形态优良，经过感应均热后，浆料内部的温度场分布均匀，初生α—Al晶粒更圆整．半固态A356铝合金的浆料温度、压射比压和冲头速度对浆料的充填行为有较大的影响．较高的浆料温度、压射比压和冲头速度都有利于半固态铝合金浆料的充填．在本文的实验条件下，合适的浆料温度为585-595℃，压射比压为15-25MPa，冲头速度为0．072-0．12m／s．得到的流变压铸件的组织分布均匀，无明显的固液相偏析．     

半固态AlSi7Mg铝合金的新型流变成形

采用新型流变成形技术，研究了压射比压与压射速度对半固态AlSi7Mg铝合金流变压铸过程的影响．结果表明：将低过热度浇注与短时弱电磁搅拌相结合，能制备出均匀的半固态AlSi7Mg铝合金浆料，适合流变压铸，流变成型参数范围较宽，有利于提高压铸件的质量．试片的壁厚、压射比压和压射速度都对半固态AlSi7Mg合金浆料的充填性有较大的影响．对于10mm的试片，压射比压应〉15MPa，压射速度应≥0．384m／s；而对于5mm的试片，压射比压应≥20MPa，压射速度应≥1．152m／s．     

A357铝合金半固态流变压铸成形组织工艺研究

介绍了一种实验室自行研制的半固态浆料制备及流变成形设备,该设备主要由熔炼炉、剪切制浆装置、温度控制系统、气体保护装置、连接装置及压铸系统组成.研究了在不同工艺条件下通过该流变成形设备制备A357铝合成形件的组织特点.探讨了半固态流变压铸过程中的凝固行为.实验结果表明:通过该实验设备能有效的消除普通铸造中出现的粗大树枝晶,制备出细小、圆整且均匀分布的半固态组织,而且能消除铸件中的气孔和显微疏松.剪切速率的增大有利于半固态A357铝合金初生α1-Al晶粒的形成及球化.在半固态浆料制备过程中,以初生α1-Al晶粒的形成为主;在随后的压铸过程中,则以较为细小的二次凝固α2-Al晶粒的形成为主.     

铝合金压铸工艺数值模拟分析

采用压铸工艺成形铝合金薄壁长轴类零件。首先根据压铸模具浇注系统的设计原则,对铝合金件压铸模的浇注系统进行了设计计算;其次运用procast软件对铝合金压铸成形工艺进行数值模拟,根据压铸过程中的温度场云图,进行了压铸模具的热平衡分析和压铸件的充型凝固分析;最后针对模拟的结果进行了压铸模具的设计。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.