Effect of Ta on structure and mechanical properties of (Ti,Ta,W)(C,N)–Co cermets

The effect of Ta on the structure and mechanical properties of (Ti,Ta,W)(C,N)–Co cermets was investigated. A series of alloys of varying nominal composition were manufactured following normal powder metallurgical procedures. The alloys were characterized and their performance in metal cutting was evaluated. It was found that Ta enhances the resistance to plastic deformation (PD) of this system. By combining sets of alloys, several explanations for this enhancement could be eliminated. Plastic deformation was found to be caused by grain boundary sliding. Ta is believed to influence the interfacial energies of the system, yielding a stronger hard phase skeleton, which restricts grain boundary sliding.     

A model for micro-slip between flat surfaces based on deformation of ellipsoidal elastic asperities—parametric study and experimental investigation

Micro-slip is a phenomenon that occurs between contacting surfaces when a frictional load, less than that necessary to produce macro-slip, is applied to the contacting surfaces. A model is evaluated for micro-slip between a flat smooth surface and a flat rough surface. The rough surface is covered with uniformly distributed ellipsoidal elastic asperities. The results from simulations of the model show that anisotropy, material combination and number of contacts of the contacting surfaces influence the tangential stiffness at zero displacement, the length of the micro-slip zone and the energy dissipated in the contact. An experimental investigation verifies the results computed by the model.     

Roll forming of partially heated cold rolled stainless steel

Today you will find roll formed details in many different products, for example buildings, household appliances and vehicles. The industry, in order to save weight, tends to use more and more high strength steel. The disadvantage with these materials is that they can be difficult to form due to reduced ductility. A way to increase the ductility in the forming areas is by partially heat the steel.It is shown that partial heating substantially increases the ductility of high strength steel and make it possible to roll form large bend angles. When roll forming, the material will work hardening almost to the as-received condition in the outer and inner radius of the roll formed profile. Furthermore, the heating power decides the bend angle obtained. Finally, the mechanical properties after heating and roll forming are discussed.     

Matrix method for relating base current ratios to field ratios ofAM directional stations

A matrix method for relating the field ratios to the voltage sources is presented. As a moment-method program is running, the field and base current for each tower is recorded. Matrices that relate base currents to field ratios, can be extracted from this data or by inverting a matrix. This method is an exact solution and requires only one run of the moment-method program. For this reason, it is superior to other iterative processes     

On the relations between color,gloss, and surface texture in injection‐molded plastics

The relation between color and gloss of injection‐molded plastic specimens was evaluated by means of a 45°/0° geometry spectrophotometer and a glossmeter. The specimens were plaques having one smooth, glossy field and one rougher, textured region made of two different polymeric materials (acrylonitrile‐butadiene‐styrene and polypropylene) in a range of colors. A significant influence of the lightness L* of the specimens on the measured gloss of the textured field, with a low gloss appearance, was found. This can probably be attributed to a contribution from bulk scattering, which is linked to the reflectance from within the specimen. The influence of texture on the measured color of the plaques was assessed by evaluating the color difference between the smooth field and the more textured area on the specimens. When the surface was textured, the color changed; in general it became lighter and less saturated. The magnitude of the change depended on the color of the material. The darker the material was, the larger was the increase in lightness L* as the surface became rougher. The shift in chroma C* was determined not only by the saturation but also by the lightness of the specimens. Darker specimens exhibited a larger decrease in chroma when the surface was textured. The change in the measured color caused by increasing the surface roughness could be predicted in a satisfactory manner using a model developed for xerographic printing paper. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 291–298, 2009     

Low‐Temperature Superionic Conductivity in Strained Yttria‐Stabilized Zirconia

Very high lateral ionic conductivities in epitaxial cubic yttria‐stabilized zirconia (YSZ) synthesized on single‐crystal SrTiO₃ and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ～1 Ω^?1cm^?1) are observed at 500 °C for 58‐nm‐thick films on MgO. The results indicate a superposition of two parallel contributions – one due to bulk conductivity and one attributable to conduction along the film–substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350 °C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk‐like conductivity is observed. The films have a negligible grain‐boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150–500 °C are of great fundamental importance but may also be technologically relevant for low‐temperature applications.     

Inhibition of Human DHODH by 4‐Hydroxycoumarins,Fenamic Acids,and N‐(Alkylcarbonyl)anthranilic Acids Identified by Structure‐Guided Fragment Selection

A strategy that combines virtual screening and structure‐guided selection of fragments was used to identify three unexplored classes of human DHODH inhibitor compounds: 4‐hydroxycoumarins, fenamic acids, and N‐(alkylcarbonyl)anthranilic acids. Structure‐guided selection of fragments targeting the inner subsite of the DHODH ubiquinone binding site made these findings possible with screening of fewer than 300 fragments in a DHODH assay. Fragments from the three inhibitor classes identified were subsequently chemically expanded to target an additional subsite of hydrophobic character. All three classes were found to exhibit distinct structure–activity relationships upon expansion. The novel N‐(alkylcarbonyl)anthranilic acid class shows the most promising potency against human DHODH, with IC₅₀ values in the low nanomolar range. The structure of human DHODH in complex with an inhibitor of this class is presented.     

Fe(O)/lignitic coal: an efficient and mechanically stable reactive material for purification of water containing heavy metals, radionuclides, and nitroaromatics

Mine water in the former uranium mine of K?nigstein (Saxony, Germany) contains high concentrations of acid, sulfate, iron, aluminum, various heavy metals, radionuclides, and nitroaromatics. Research has been conducted for several years to establish the extent to which reduction of pollutant concentrations can be positively influenced and accelerated by storage of reactive materials in mine cavities. Investigations were made at different scales to test and select materials with respect to maximum fixation of contaminants (underground column tests) to examine hydraulic effects (underground large-scale column tests) and to optimize material properties (laboratory tests). The investigations have shown that a mixture of Fe chips and lignitic coal is capable of efficiently cleaning acid and contaminant-containing mine water. The examined material is easily available and compatible with the environment. A large-scale application of such a reactive barrier is being considered for mine water treatment in the future and is deemed to be a reasonable conception for a safety component after conclusion of the flooding.