X-ray Radioscopic Visualization of Bubbly Flows Injected Through a Top Submerged Lance into a Liquid Metal

Metallurgical and Materials Transactions B - We present an experimental study on the formation and behavior of a liquid metal bubbly flow arising from a downward gas injection through a top...     

Messung der Reflexion von Wärmestrahlen an technischen Oberflächen

Zusammenfassung Die Richtungsverteilung reflektierter W?rmestrahlen wird an Oberfl?chen, die in der Technik h?ufig vorkommen, ausgemessen. VDI Mitteilung aus dem Maschinenlaboratorium der Technischen Hochschule Danzig-Langfuhr     

Über die Richtungsverteilung der Wärmestrahlung von Oberflächen

Ohne Zusammenfassung VDI     

Corrosion behaviour of carbon steel coated with Zr‐based metallic glass

Zr₅₅Cu₃₀Al₁₀Ni₅ glassy alloy samples were prepared by the single roller melt spinning technique in an argon atmosphere. Amorphous ribbons were coated on carbon steel by the electron beam technique. Subsequently, the coated region was remelted to study its effect on the corrosion performance. The microstructure of the ribbons and of coated steel samples was characterized by X‐ray diffraction (XRD) and optical microscopy (OM). Potentiodynamic polarization studies were carried out in 0.1 M Na₂SO₄ electrolytes at pH = 8 and pH = 2. The coated samples showed a significant increase in corrosion resistance compared to the base carbon steel in both sulphate electrolytes. The pitting corrosion behaviour of the coated samples has been examined in 0.01 M NaCl electrolyte and was found to be poor. Furthermore, the galvanic and crevice corrosion behaviour of these alloys has been evaluated in the chloride electrolyte.     

Strukturaufklärung cyclischer Fettsäuremethylester V: Massenspektrometrie isomerer Phenylundecansäure-methylester

Elucidation of Structure of the Methyl Esters of Cyclic Fatty Acids V: Mass-Spectrometry of Isomeric Methyl Esters of Phenyl Undecanoic Acid Isomeric phenyl undecanoic acids obtained by the Friedel-Crafts reaction of benzene with 10-undecenoic acid were investigated as methyl esters using capillary gas-chromatography – mass spectrometry (GC-MS). The isomers could be identified as methyl esters of (5-), 6-, 7-, 8-, 9- and 10 phenyl undecanoic acids. The fragmentation due to electron bombardment is discussed.     

Martensitic transformation and thermal cycling effect in Cu–Co–Zr alloys

Cu_50?xCo_x Zr₅₀ (x = 0, 0.5, 1, 2, 3, 4 and 5 at.%) alloys were cast in a cylindrical copper mold by a suction casting device. In order to investigate the thermal behavior of the as-cast rods, the samples were heated from 313 to 573 K and then cooled down to about 253 K. The structure of the samples was studied by X-ray diffraction and optical microscopy. Thermal cycling measurements were also done for alloys with 2, 3, 4 and 5 at.% cobalt. It was found that increasing the cobalt content decreases martensite (M_s) and austenite (A_s) start temperatures, while it increases the temperature region in which austenite is stable. Thermal cycling measurements revealed that by increasing the number of cycles, the austenite start temperature increases while martensite start temperature shifts to lower temperatures.     

Investigations of Bearing Failures Associated with White Etching Areas (WEAs) in Wind Turbine Gearboxes

A critical problem for wind turbine gearboxes is failure of rolling element bearings where axial cracks form on the inner rings. Metallurgical analyses show that the failure mode is associated with microstructural alterations manifested by white etching areas (WEAs) and white etching cracks (WECs). This article presents field experience from operating wind turbines that compares performance of through-hardened and carburized materials. It shows that through-hardened bearings develop WEA/WECs and fail with axial cracks, whereas carburized bearings do not. In another comparison of two rotor bearings with different carburized metallurgies, one bearing developed WEA/WECs and failed by macropitting, whereas the other bearing did not develop WEAs or WECs and did not fail. The field experience shows that a carburized bearing that has a core with low carbon content, high nickel content, greater compressive residual stresses, and a higher amount of retained austenite provides higher fracture resistance and makes carburized bearings more durable than through-hardened bearings in the wind turbine environment.