Microstructure of thin-wall ductile iron castings

Step plate castings with section thicknesses of 1.5 mm to 6 mm and individual (single) castings with section thicknesses of 2 mm to 6 mm were produced using a ductile iron chemistry. Microstructures of these thin wall ductal iron castings were characterized quantitatively using an image analyzer. Matrix structure (amount of pearlite, ferrite, and massive carbides) and graphite structure (volume fraction, nodule size, nodule content, and nodularity) were investigated as a function of section thickness. Pearlite content, nodule count, and nodularity increased with decreasing section thickness, whereas the nodule size decreased. Nodule content exceeded 2000 nodules per mm{sup 2} at the thinnest sections. Statistical analysis was performed to investigate the effect of casting parameters on the microstructure

Steam turbine materials and corrosion

Ultra-supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include power generation from coal at 60% efficiency, which would require steam temperatures of up to 760°C. This project examines the steamside oxidation of candidate alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines. As part of this research a concern has arisen about the possibility of high chromia evaporation rates of protective scales in the turbine. A model to calculate chromia evaporation rates is presented

Influence of atypical retardation pattern on the peripapillary retinal nerve fibre distribution assessed by scanning laser polarimetry and optical coherence tomography

Aim: To investigate the influence of atypical retardation pattern (ARP) on the distribution of peripapillary retinal nerve fibre layer (RNFL) thickness measured with scanning laser polarimetry in healthy individuals and to compare these results with RNFL thickness from spectral domain optical coherence tomography (OCT) in the same subjects. Methods: 120 healthy subjects were investigated in this study. All volunteers received detailed ophthalmological examination, GDx variable corneal compensation (VCC) and Spectralis-OCT. The subjects were divided into four subgroups according to their typical scan score (TSS): very typical with TSS=100, typical with 99≥TSS ≥91, less typical with 90≥TSS ≥81 and atypical with TSS ≤80. Deviations from very typical normal values were calculated for 32 sectors for each group. Results: There was a systematic variation of the RNFL thickness deviation around the optic nerve head in the atypical group for the GDxVCC results. The highest percentage deviation of about 96% appeared temporal with decreasing deviation towards the superior and inferior sectors, and nasal sectors exhibited a deviation of 30%. Percentage deviations from very typical RNFL values decreased with increasing TSS. No systematic variation could be found if the RNFL thickness deviation between different TSS-groups was compared with the OCT results. Conclusions: The ARP has a major impact on the peripapillary RNFL distribution assessed by GDx VCC; thus, the TSS should be included in the standard printout

Soaking of Pine Wood Chips with Ionic Liquids for Reduced Energy Input during Grinding

Abstract Ionic liquids are of great interest as potential solvents/catalysts for the production of fuels and chemicals from lignocellulosic biomass. Attention has focussed particularly on the pretreatment of lignocellulose to make the cellulose more accessible to enzymatic hydrolysis. Any biomass processing requires a reduction in the size of the harvested biomass by chipping and/or grinding to make it more amenable to chemical and biological treatments. This paper demonstrates that significant energy savings can be achieved in the grinding of pine wood chips when the ionic liquid is added before the grinding operation. We show that this is due to the lubricating properties of the ionic liquids and not to physico-chemical modifications of the biomass. A brief impregnation of the chipped biomass results in higher savings than a longer treatment

Advanced titanium processing

The Albany Research Center of the U.S. Department of Energy has been investigating a means to form useful wrought products by direct and continuous casting of titanium bars using cold-wall induction melting rather than current batch practices such as vacuum arc remelting. Continuous ingots produced by cold-wall induction melting, utilizing a bottomless water-cooled copper crucible, without slag (CaF2) additions had minor defects in the surface such as ''hot tears''. Slag additions as low as 0.5 weight percent were used to improve the surface finish. Therefore, a slag melted experimental Ti-6Al-4V alloy ingot was compared to a commercial Ti-6Al-4V alloy ingot in the areas of physical, chemical, mechanical, and corrosion attributes to address the question, ''Are any detrimental effects caused by slag addition''