Advanced Engineering Materials

Cover image for Advanced Engineering Materials

February, 2004

Volume 6, Issue 1-2

Pages 3–102

    1. Hydrogen in Nano-sized Metals (pages 11–21)

      A. Pundt

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300557

      Systems with small sizes show significant changes compared to the bulk system. These changes are of major interest regarding the size reduction of technological applications. The hydrogen-metal system can be used as a model alloy to study small size features: shifted phase boundaries and sloped isotherms are found and, also, new materials structures. Most features can be attributed to surface- and interface contributions as well as to mechanical stress.

    2. Powder Metallurgical Processing of Intermetallic Gamma Titanium Aluminides (pages 23–38)

      R. Gerling, H. Clemens and F.P. Schimansky

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200310559

      Intermetallic γ-TiAl-based alloys represent a new class of light-weight structural materials for use at high temperatures. Because of their unique properties these alloys are considered for applications in aerospace and automotive industries. During the last decade both, alloy development and materials processing progressed significantly. The powder metallurgical processing of γ-TiAl-based alloys is discussed in this review article.

    3. Optical and Dielectric Anisotropy in Polyimide Nanocomposite Films Prepared from Soluble Poly(amic diethyl ester) Precursors (pages 39–43)

      Y. Kim, W.H. Goh, T. Chang, C.-S. Ha and M. Ree

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300546

      Optical and dielectric anisotropy of the polyimide nanocomposite films prepared from soluble poly(amic-diethyl ester) precursors has been studied using a prism coupling technique. The composite films showed nonlinear dependence of in-plane and out-of-plane refractive indices (dielectric constants) on the composition. Consequently the in-plane dielectric constant of the composite films was not much reduced owing to the still high in-plane orientation of the rod-like polyimide, leading to the quite high dielectric anisotropy.

    4. Polymer Nanocomposites with Fullerene-like Solid Lubricant (pages 44–48)

      L. Rapoport, O. Nepomnyashchy, A. Verdyan, R. Popovitz-Biro, Y. Volovik, B. Ittah and R. Tenne

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300512

      Recent experiments showed that the addition of inorganic fullerene-like (IF) WS2 or MoS2 solid lubricant nanoparticles in oil, grease or impregnated into porous matrix provides remarkable lubricating properties of friction pairs in a wide range of operating conditions. Inorganic nanoparticles filled polymer composites show low friction and high wear resistance. This work reports the first attempt to fill polymers with hollow solid lubricant nanoparticles. It was found that application of the IF solid lubricant nanoparticles leads to a considerable improvements in the tribological behavior of the nanocomposites. The morphology of the surface layers and the mechanism of the friction reduction by the IF nanoparticles are discussed.

    5. Demonstration of Carbon Nanotube Coated Metals Reinforcing Polymer Matrix Composites (pages 48–52)

      R.L. Vander Wal and L.J. Hall

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300514

      Advancements in interfacial bonding will improve all types of polymer matrix composites (PMCs) using regular carbon fibers, metals or metal meshes by significantly improving strength, toughness, thermal conductivity, gas impermeability and electrical conductivity. In this article we demonstrate a distributed interface between carbon nanotube (CNT) coated stainless steel (SS) metal foils and a host polymer matrix. With the metal acting as both catalyst and support, the CNTs bridge the interface between the two dissimilar materials to create a volumetrically distributed 3-dimensional interface.

    6. Tuning the Refractive Index of Polymers for Polymer Waveguides Using Nanoscaled Ceramics or Organic Dyes (pages 52–57)

      J. Böhm, J. Haußelt, P. Henzi, K. Litfin and T. Hanemann

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300542

      Plastic Optical Fibers (POF) show advantageous properties like high flexibility and their cost advantage in comparison to glass fibers. The refractive indices of core and cladding have to be modified in order to get total reflectance. Thus, there is a strong demand for refractive index adjustable polymers with improved transmission properties in the visible and the NIR range. Inorganic nanosized particles or organic dyes homogeniously dispersed or solved in the polymer matrix allow a tailored increase or decrease of the refractive index of various polymers.

    7. Sol–Gel Coatings as Active Barriers to Protect Ceramic Reinforcement in Aluminum Matrix Composites (pages 57–61)

      J. Rams, A. Ureña and M. Campo

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300519

      Silica obtained through a sol–gel process is used as a coating for ceramic reinforcements (SiC) in aluminium matrix composite materials. The interaction between molten aluminium and the coated particles during material casting can be controlled by means of the thermal treatment given to the coating. Wettability is increased because the coating reacts with molten aluminium, and the formation of the degrading aluminium carbide is inhibited.

    8. The Enhancement of Metal-to-Ceramics Adhesion Bond Under Sintering in Microwave Fields (pages 61–64)

      E.G. Pan and A.A. Ravaev

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300536

      The article summarizes some of the most interesting results of experimental investigations searching for new ways of improving the adherence of oxide ceramics to alloys in metal-ceramic structures. The method described in the article and tested with dental porcelain and Ni-Cr alloy allows to increase the adherence of such structures by several times. The physical phenomena identified in the experiments are of fundamental nature, particularly, the abnormally high metal diffusion into ceramics and unusual behaviour of materials under the effect of electromagnetic field.

    9. Influence of Boron on the Microstructure of Polymer Derived SiCO Ceramics (pages 64–68)

      A. Klonczynski, G. Schneider, R. Riedel and R. Theissmann

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300525

      The thermal decomposition and crystallisation behaviour of boron containing siliconoxycarbide (SiCO) ceramics were studied. The samples were prepared by pyrolysis of SiO2/B2O3 filled poly(dimethylsiloxanes) at 1300°C and subsequent annealing at T > 1300°C. TEM and XRD investigations show the formation of β-SiC during annealing at 1300°C. The resulting material can be described as a borosilicate glass with homogeneously dispersed nano β-SiC crystals.

    10. Fabrication of Mullite Powders by a Novel Processing (pages 69–71)

      Y.F. Tang, L. Feng, Y.F. Chen and A.D. Li

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300521

      A novel and general processing (heterogeneous nucleation and growth processing) was used to prepare composite coating particles with homogeneous component distribution. Composite coating particles consisting of α-Al2O3 cores with an outer amorphous silica layer were prepared by this processing using an ethanol suspension containing ammonia, tetraethylorthosilicate and α-Al2O3. Fine mullite powders (d50 = 0.73 μm) were fabricated by calcinating these particles at 1500 °C for 2 h.

    11. Effectiveness of Surface Composite Layers on Impact Resistance of Brittle Materials (pages 71–73)

      Y. Kim, S. Zhu, Y. Kagawa and H. Kasano

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300530

      Single and double layers of woven fabric Al2O3 fiber-Al2O3 matrix composites are used as a surface protective layer for a brittle material, borosilicate glass substrate. The effect of a thin damage-tolerant surface composite layer on the damage caused by steel ball projectiles is examined. Damage behavior of the surface composite layer-bonded specimen with impact speed of 40 and 110 m/s shows significant effect of the composite layer on the damage. It is clearly demonstrated that the concept of a thin surface composite layer is effective for reducing impact damage on the surface of brittle materials.

    12. Multi-Principal-Element Alloys with Improved Oxidation and Wear Resistance for Thermal Spray Coating (pages 74–78)

      P.-K. Huang, J.-W. Yeh, T.-T. Shun and S.-K. Chen

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300507

      Multi-principal-element alloy coatings of Al-Si alloys were prepared by a plasma spray method. They not only exhibited a good oxidation resistance up to 1000 °C, but also possessed an excellent abrasive wear resistance approximately two times higher than those of SUJ2 and SKD61. Moreover, they displayed a high temperature precipitation hardening phenomenon up to 1100 °C which is novel and seldom found in conventional alloys.

    13. Iso-work Increment Assumption for Heterogeneous Material Behaviour Modelling (pages 79–83)

      O. Bouaziz and P. Buessler

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300524

      Assuming an equi-incremental mechanical work in each constituent in stress-strain mixture law, this article focuses on the interest of this approach through comparison with miscellaneous experimental results and with other modelling methods as Taylor, Sachs, self-consistent or 3D finite element modelling.

    14. Research Directions in Magnesium Corrosion Arising from the Wolfsburg Conference (pages 83–84)

      A. Atrens

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200411001

      Following a recent review article in this journal and a keynote lecture at “6th International Conference on Magnesium Alloys and Their Applications” suggestions for research directions in magnesium corrosion are provided and discussed.

    15. Multi-Criteria Material Selection in Engineering Design (pages 84–92)

      P. Sirisalee, M.F. Ashby, G.T. Parks and P.J. Clarkson

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300554

      Material selection in real-world problems normally entails considering several, usually conflicting, design criteria/objectives. Thus, a designer has to strike a balance between these objectives to find the best compromise solution for the particular application. A novel design support tool, the exchange constant chart, has been developed in order to assist designers selecting materials in such multi-criteria situations. Two case studies are presented to illustrate the use of this tool.

    16. Building The Data Warehouse For Materials Selection in Mechanical Design (pages 92–95)

      Y. Li

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300522

      The materials selection for mechanical design is a data-intensive decision-making task. It would be highly desirable to take full advantages of the latest data management techniques to support it. The data warehousing, as a new information management technology, has the eminent power of supporting a large-scale data integration and decision-making practice. Therefore the data warehousing is an attractive option to be used for the materials selection process.

    17. Materials Design for Acoustic Liners: an Example of Tailored Multifunctional Materials (pages 97–102)

      S. Gasser, Y. Brechet and F. Paun

      Version of Record online: 19 FEB 2004 | DOI: 10.1002/adem.200300545

      Relying on a model allowing to predict mechanical properties and acoustic absorption of a regular f.c.c stacking of hollow spheres, and on a functional analysis of acoustic liners for airplane engines, a methodology for optimal design of a taylored multifunctional material is proposed.