RESUMO
In lubricated tribo-contacts, hydrogen ingress in steel is possible due to chemical reactions of lubricant components like base oils or additives, and/or contamination upon service particularly water, and/or corrosion processes, and/or electrostatic fields or current flow. Absorbed by the metal, atomic hydrogen may cause serious deleterious effects on the physical-chemical and mechanical properties, reducing the material's ability to withstand the design loads. The present research work is focused on analyzing the influence of electric field on lubricating oils in contact with steel surface. In order to evaluate the possibility of atomic hydrogen generation and permeation into the steel under cathodic polarization of lubricating oils the electrochemical permeation technique developed by Devanathan and Stachurski is used. The input cell of a Devanathan-Stachurski set up is appropriately modified by realizing a very close distance between the working electrode (steel membrane) and a Pt counter electrode with the oil between. This significantly increases the sensibility of the set up and allows the application of larger voltage and higher temperature to enable hydrogen generation from lubricating oils. The complex effects of cathodic polarization, temperature, additives and presence of water in model lubricating oils on atomic hydrogen permeation into steel is discussed.
Assuntos
Hidrogênio , Aço , Aço/química , Óleos , Eletrodos , Lubrificantes , ÁguaRESUMO
Energy-filtered transmission electron microscopy (EFTEM) can be used to acquire elemental distribution maps at high lateral resolution within short acquisition times, which makes it quite efficient for a detailed characterization of nanostructures, as illustrated with examples concerning a nanostructured substituted La-based cermet compound and a nanoscale multilayer. In the first example, we show how phases in a rapidly cooled substituted LaNi5 can be visualized by recording jump ratio images. Secondly, EFTEM was capable of imaging individual nanoscale layers in a magnetic multilayer consisting of 2 nm terbium and 3 nm iron.
Assuntos
Microscopia Eletrônica/instrumentação , Microscopia Eletrônica/métodos , Fenômenos Biofísicos , Biofísica , Ferro/química , Lantânio/química , Térbio/química , Fatores de TempoRESUMO
Experiments with an antipericardium immune serum of the goat resulted in the proof of two not identical with serum proteins antigens in the pericardium. By means of the same antiserum with the help of the gel diffusion technique after Ouchterlony and immunoelectrophoresis the sera of patients with carditis or myocardial infarction, respectively, were examined for the presence of circulating tissue antigens. In 20 out of 23 patients with carditis 1 or 2 antigens were found which were not identical with normal serum proteins. In 27 cases of myocardial infarction their proof was successful only in 4 patients, in complication by a post-myocardial infarction syndrome in 2 out of 3 cases. In comparative investigations of sera of 100 healthy persons only 4 test persons showed a positive result. There was no clue for the identity of one of the antigens proved with C-reactive protein.