Showing papers in "Advanced Engineering Materials in 1999"
TL;DR: In this paper, a detailed review of the corrosion mechanisms of magnesium alloys is presented, and the basis for the design of new alloys with improved corrosion properties is provided for improving the corrosion properties.
Abstract: The high strength to weight ratio of magnesium alloys makes them extremely attractive for applications in transport or aerospace technology. However, their corrosion behavior is a major issue and one reason why they are still not as popular as aluminum alloys. This papers reviews the corrosion mechanisms of magnesium and provides the basis for the design of new alloys with improved corrosion properties.
1,922 citations
TL;DR: The author discusses some marginal design conditions applicable to the coating of implants with hydroxyapatite using the example of total hip replacement.
Abstract: Load-carrying components for artificial joints are made of bioinert alloys. Ceating bioinsrt implants with bionctive hydroxyapatite ceramics offers a potential for piolog/cal interaction between the bone and the coated int plant, which enables positive biological/chemical material connections. The author discusses some marginal design conditions applicable to the coating of implants with hydroxyapatite using the example of total hip replacement. There is highly convincing experience available from more than ten years of clinical application.
91 citations
TL;DR: A new instability-dominated picture of dynamic fracture in brittle materials has arisen as a result of intensive research over the past few years, and is based on new high-resolution measurements of crack dynamics, This may have impact on the design of new energy-absorbing materials.
Abstract: A new instability-dominated picture of dynamic fracture in brittle materials has arisen as a result of intensive research over the past few years, and is based on new high-resolution measurements of crack dynamics, This may have impact on the design of new energy-absorbing materials.
36 citations
[...]
TL;DR: In this paper, the authors evaluated the performance of different machining parameters for primary castings of the type γ-TiAl and found that there is a potential for each machining process, but a high quality of surface finish can only be achieved by some of them.
Abstract: Knowledge of the machining parameters for titanium aluminides of the type γ-TiAl is essential for the acceptance and application of this new heat-resistant light-weight material for high performance components in automobile and aircraft engines. This work evaluates drilling, turning, sawing, milling, electroerosion, grinding, and high-pressure water-jetting of primary castings. The results indicate that there is a potential for each machining process, but a high quality of surface finish can only be achieved by some of the processes.
33 citations
33 citations
32 citations
32 citations
TL;DR: The microstructure of this new class of lightweight titanium aluminide alloys is controlled by the processing parameters for manufacturing semifinished products or components, and by minor modifications of the alloy composition as discussed by the authors.
Abstract: The microstructure of this new class of lightweight titanium aluminide alloys is controlled by the processing parameters for manufacturing semifinished products or components, and by minor modifications of the alloy composition These materials exhibit excellent physical and mechanical properties for the use as components in automotive and jet engines, especially in rotating and oscillating parts
30 citations
TL;DR: Cutting tools coated with polycrystalline diamond (DP) showed a superior behavior in dry machining of magnesium alloys compared to uncoated or TiN-coated cermented carbide tools.
Abstract: Cutting tools coated with polycrystalline diamond (DP) show a superior behavior in dry machining of magnesium alloys compared to uncoated or TiN-coated cermented carbide tools. With their usage one can best avoid adhesion between cutting tool and workpiece material as well as material build-up. Chip temperature and thus the danger of chip ignition can be reduced due to low machining forces when using DP tools. They are also preferred for machining magnesium-based MMCs.
27 citations
TL;DR: In this paper, a combination of advances in materials and process development has led to a significant reduction in the uncertainties and risks associated with the estimation of mechanical failure probabilities and component for brittle materials in service.
Abstract: The design of components for applications requiring high stiffness, hardness and wear resistance under extreme conditions of load and temperature leaves little choice for materials selection outside the realm of hard materials. But a combination of advances in materials and process development has led to a significant reduction in the uncertainties and risks associated with the estimation of mechanical failure probabilities and component for brittle materials in service.
24 citations
TL;DR: In this article, numerical simulation of die compaction and sintering is used to reduce development times and costs or optimize production cycles, and even qualitative predictions of crack formation are possible.
Abstract: Numerical simulation of die compaction and sintering is a promising tool for reducing development times and costs or optimizing production cycles. Finite element simulations allow qualitative and quantitative predictions of undesirable distortions after firing. Even qualitative predictions of crack formation are possible.
TL;DR: The CESP Process as discussed by the authors allows the production of resorbable implants serving not only as a replacement for organs but also as drug-release systems, and the foam structure and the ability to influence the bubble diameter enables tailoring of the mechanical properties and degradation behavior.
Abstract: Polymers based on glycolic and lactic acid are the most widely used type of resorbable polymers The CESP Process (controlled expansion of saturated polymers) allows the production of resorbable implants serving not only as a replacement for organs but also as drug-release systems The foam structure and the ability to influence the bubble diameter enables tailoring of the mechanical properties and degradation behavior
TL;DR: In this paper, a SiC fiber-bonded ceramic was developed to solve the problem of low fracture resistance of high-temperature and high thermal conductivity of ceramic materials.
Abstract: Low fracture resistance is one of the most serious limitations of ceramic materials. The new SiC fiber-bonded ceramic presented here was developed to address this problem. The thermally conductive material is a candidate for such demanding applications as gas turbine engine hot section components, where its high-temperature capability, high thermal conductivity, and low density make it very attractive for replacement of heavy metal super alloy components. Synthesized by hot-pressing the material with the commercial name Sintered Tyrannohex consists of hexagonal columnar SiC fibers with a thin interfacial carbon layer between them.
TL;DR: In this article, a new direct foaming approach that allows the production of SiOC foams in a one-step process is described, and a great versatility in terms of foam morphology and possible shapes enables the synthesis of materials with tailored composition and properties.
Abstract: Cellular ceramics are the material of choice in various high temperature technological applications and new applications are now being found in the electronic and biomedical area. Paolo Colombo here describes a new direct foaming approach that allows the production of SiOC foams in a one-step process. Additionally, a great versatility in terms of foam morphology and possible shapes enables the synthesis of materials with tailored composition and properties.
TL;DR: In this paper, a 3-3 mullite-Al or alumina-Al composites via fused depostion (FD) has been proposed to control the connectivity and spatial distribution of two or more component phases.
Abstract: The principal difficulty in fabricating 3-3 composites is in controlling the connectivity and spatial distribution of two or more component phases. Fabrication of 3-3 mullite�Al or alumina�Al composites via fused depostion (FD) has several inherent advantages over some of the other approaches for processing similar composites. Using FD processes not only can the shape or macrostructure of the part be controlled via CAD, but also the microstructure. This approach can help to design and develop an optimal microstructure for any specific application.
TL;DR: Aqueous-based polyurethane has become an important substitute for the conventional solvent-based polymer as mentioned in this paper, and the properties of aqueous based polyurethsane can be easily modified by hybridization with other compatible polymers via post-curing reactions.
Abstract: Aqueous-based polyurethane has become an important substitute for the conventional solvent-based polymer. The properties of aqueous-based polyurethane can be easily modified by hybridization with other compatible polymers via post-curing reactions.
TL;DR: In this article, the mechanism and kinetics of internal nitridation of Ni-based alloys are discussed, where the Ni oxide layer loses its effectiveness because of pores, cracks, or spalling.
Abstract: Nitridation of Ni-based alloys may occur when the protective oxide layer loses its effectiveness because of pores, cracks, or spalling. Components under high thermal or mechanical loading are especially prone to such damages. Nitrogen causes internal corrosioii by chemical reaction with alloying elements like Ti and Al, commonly present in commercial Ni-based alloys. The mechanism and kinetics of the internal nitridation is discussed by the authors.
TL;DR: Li et al. as discussed by the authors proposed a Solid State Microstructured Microstructures (SMSM) based approach to solve the problem of solid state microstructures, which can be found in NNanjing Univ, National Univ Singapore, Dept Phys, Singapore 119260.
Abstract: Nanjing Univ, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China. Nanjing Univ, Dept Phys, Nanjing 210093, Peoples R China. Acad Sinica, Inst Met Res, RSA, Natl Key Lab, Shenyang 110015, Peoples R China.;Li, JM (reprint author), Natl Univ Singapore, Dept Phys, Singapore 119260, Singapore
TL;DR: In this article, a non-destructive surface analysis of thin films on metals using spectroscopic ellipsometry has been proposed, which allows the morphological and chemical characterization of these films.
Abstract: New spectroscopic ellipsometry techniques are very promising for the non-destructive surface analysis of of thin films on metals. Infrared spectroscopic ellipsometry allows the morphological and chemical characterization of these films, and recent results are presented here.
TL;DR: In this article, the effects of the mechanical and thermal energy exerted by turning and grinding processes on the materials surfaces were reviewed and the authors recommended to always take surface area requirements into account.
Abstract: Hard alloys count among the hard-to-machine materials. Performance characteristics such as high hardness and wear resistance as well as the structural difference between hard phases and metallic matrix impede their machineability. The authors review the effects of the mechanical and thermal energy exerted by turning and grinding processes on the materials surfaces. Since high thermal surface loading may cause crack formation in hard phases as well as hardness increase and softening in the case of iron-based alloys they recommend to always take surface area requirements into account.
TL;DR: Combining molybdenum and zirconia such that a cermet could be made to contain a maximum percentage of exide, while still maintaining a continuous metal matrix is the goal of as discussed by the authors.
Abstract: Combining molybdenum and zirconia such that a cermet could be made to contain a maximum percentage of exide, while still maintaining a continuous metal matrix is the goal of the authors. With their innovative method they get an electrically conductive Mo-ZrO 2 cermet with a low metal content and high thermal-shock resistance.