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Resistant Materials (resistant + material)
Selected AbstractsHigh-Pressure Synthesis of Tantalum Nitride Having Orthorhombic U2S3 StructureADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Andreas Zerr Abstract Among binary compounds, there is a high potential for discovery of novel members (polymorphic phases or compounds) of the nitrides of transition metals group due to a pronounced dependence of the oxidation state of the metals (M) on pressure. The power of high pressure,high temperature (HP-HT) route for synthesis of binary nitrides has already been demonstrated by the discovery of cubic nitrides of the group 4 and 14 elements, of crystalline polymorphs of P3N5, and by reports on formation of four noble metal nitrides. It is anticipated that such HP products exhibit, in addition to enhanced elastic and mechanical behavior, other functional properties making them interesting for industrial applications. Here, HP,HT synthesis research is extended to nitrides of group 5 elements, resulting in the discovery of a novel hard tantalum nitride, exhibiting U2S3 structure: , -Ta2N3 (Pbnm, a,=,8.1911(17),Å, b,=,8.1830(17),Å, c,=,2.9823(3),Å). The stoichiometry is supported by two independent means, verifying that , -Ta2N3 is the first thermodynamically stable transition metal nitride with a N:M ratio exceeding 4:3. Due to its high hardness and peculiar texture (needle-like and granular crystallites), , -Ta2N3 may find practical applications as a hard fracture resistant material. [source] High-Field Scanning Probe Lithography in Hexadecane: Transitioning from Field Induced Oxidation to Solvent Decomposition through Surface Modification,ADVANCED MATERIALS, Issue 21 2007I. Suez High field scanning probe lithography in hexadecane leads to two different chemical reactions depending on surface hydrophilicity. On a hydrophilic surface, oxidation of the sample occurs; a hydrophobic surface, results in solvent decomposition and nanoscale deposition of etch resistant material. The features are characterized with photoelectron emission microscopy and are carbonaceous in nature with a highly cross-linked bonding network. Tone reversal in a fluorinated etch is achieved. [source] Nanoscale Grain Refinement and H-Sorption Properties of MgH2 Processed by High-Pressure Torsion and Other Mechanical Routes,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Daniel Rodrigo Leiva MgH2 is a promising material for solid-state hydrogen storage due to its high gravimetric and volumetric storage capacity and its relatively low cost. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high-energy ball-milling (HEBM) in order to obtain more air resistant materials and reduce processing times. In this work, Mg, MgH2, and MgH2,Fe mixtures were severely mechanically processed by different techniques such as high-pressure torsion (HPT), extensive cold forging, and cold rolling. A very significant grain refinement was achieved when using MgH2 instead of Mg as raw material. The mean crystallite sizes observed ranged from 10 to 30,nm, depending on the processing conditions. Enhanced H-sorption properties were observed for the MgH2 -based nanocomposites processed by HPT when compared with MgH2 mixtures. Additionally, cold forging and cold rolling also proved effective in nanostructuring MgH2. These results suggest a high potential for innovative application with the use of low cost mechanical processing routes to produce Mg-based nanomaterials with attractive hydrogen storage properties. [source] The Characterization of Local Deformation and Fracture Properties , a Tool for Advanced Materials Design,ADVANCED ENGINEERING MATERIALS, Issue 11 2006O. Kolednik Novel experimental techniques have been recently developed to measure local deformation and fracture properties. The techniques comprise quantitative fracture surface analysis and in-situ loading experiments in combination with digital image analysis. Examples are presented, demonstrating how these methods can be used to investigate the damage evolution in materials, to improve tools for the numerical simulation, and for the design of more fracture resistant materials and components. [source] Screening for Barley yellow dwarf virus -Resistant Barley Genotypes by Assessment of Virus Content in Inoculated SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2006Abstract The content of Barley yellow dwarf virus (BYDV) in roots and leaves of barley seedling plants differing in their level of resistance was assessed by quantitative ELISA 1,42 days after inoculation with the strain of BYDV (PAV). High virus accumulation in roots and low concentration in leaves was characteristic of the period 9,15 days after inoculation. In leaves, the differences in virus content between resistant and susceptible genotypes became significant after 15 days and resistance to virus accumulation was better expressed 30,39 days after inoculation. Roots of resistant materials exhibited evident retardation of virus accumulation and the greatest difference in virus content between resistant and susceptible plants was detected 9 days after inoculation. By these criteria, the selected winter and spring barley cultivars and lines (in total 44 materials) fell in to five groups according to field reactions and the presence or absence of the Yd2 resistance gene. There were highly significant and positive relations between ELISA values and 5-year field data on symptomatic reactions and grain-yield reductions due to infection. Using the described method, resistant and moderately resistant genotypes (both Yd2 and non- Yd2) were significantly differentiated from susceptible genotypes. The possible use of this method in screening for BYDV resistance is discussed. [source] | ||||||||||