Wear and corrosion interaction of AISI D2 in an acidic environment

The tribological, electrochemical and tribo-electrochemical behavior of bare AISI D2 was studied. The tribological aspects were tested by pin on disc with an aluminum oxide ball as counter body, the electrochemical tests were performed in an aqueous solution of citric acid and the tribo-electrochemical evaluation was through a combination of both tests. AISI D2 steel presented abrasive wear in dry and wet conditions, such type of wear occurred due to stick-slip motion, moreover, in wet conditions the alloy corroded at corrosion current values around 10-6 A/cm2.  The damage produced over the wear track was larger under wet conditions than for the dry conditions

Electron evaporation of carbon using a high density plasma

High-density plasmas are often used either in the preparation of thin films or for the modification of surfaces; nitriding. However, except for collision-driven chemical reactions the electrons present are not used, although electron bombardment heating of the work piece nearly always occurs. Principally it is the ions and neutrals that are utilised for materials processing. By suitable biasing of a conducting source material the electrons can be extracted from a highdensity low-pressure plasma to such an extent that evaporation of this source material can be achieved. Due to the presence of the plasma and the flux of electrons a large proportion of the evaporant is expected to be ionised. We have used this novel arrangement to prepare thin films of carbon using a resonant high-density argon plasma and a water cooled rod of high purity graphite. Multiple substrates were used both outside of, and immersed in, the plasma. We report the characteristics of the plasma (electron temperature and density, the ion energy and flux, and optical emission spectra), the deposition process (the evaporation rate and ion/neutral ratio), and the film properties (IR and UV/Vis absorption spectra, Raman spectra, elemental analysis, hardness and refractive index

NACA Research Memorandums

Report presenting lift, drag, and pitching-moment characteristics for a wing-body combination for a range of Mach numbers. The wing had an aspect ratio of 3.1, a sweepback of the leading edge of 19.1 degrees, a taper ratio of 0.39, and a biconvex profile with a thickness of 3 percent of the chord. Results regarding aerodynamic characteristics and visual-flow studies are provided

Tribological, Tribocorrosion and Wear Mechanism Studies of TaZrN Coatings Deposited by Magnetron Sputtering on TiAlV Alloy

Different works have demonstrated that tantalum, zirconium, and their nitrides present good biocompatibility. Additionally, TaN and ZrN possess excellent corrosion and wear resistance. Ternary nitrides such as TiAlN have been improved in terms of their mechanical properties with respect to binary systems. Therefore, ternary nitrides as TaZrN have high potential to be used in biomedical applications. This work was focused on studying the tribological and tribocorrosion performance of a TaZrN film. The coating was deposited by DC (Direct Current) magnetron sputtering in a reactive atmosphere using Ta and Zr targets. The tribological characterization was carried out in dry (atmospheric condition) and corrosive environments (synthetic body fluid). The coated surface shows better wear resistance than the uncoated in both conditions. The wear mechanism was studied by FE-SEM (Field Emission-Scanning Electron Microscopy) and Raman confocal microscopy. The wear rate of the coated surfaces was higher in corrosive ambient than in dry conditions. The observed wear mechanism was adhesive–abrasive for lower loads and abrasive at dry conditions for an applied load of 2 N. For corrosive media the principal wear mechanism for 2 N was abrasive–corrosive. For all tests at dry conditions, the formation of a tribolayer of metal oxides, graphite, and amorphous carbon was seen

The integrated stress response prevents demyelination by protecting oligodendrocytes against immune-mediated damage

In response to ER stress, the pancreatic endoplasmic reticulum kinase (PERK) coordinates an adaptive program known as the integrated stress response (ISR) by phosphorylating the α subunit of eukaryotic translation initiation factor 2 (eIF2α). IFN-γ, which activates the ER stress response in oligodendrocytes, is believed to play a critical role in the immune-mediated CNS disorder multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE). Here we report that CNS delivery of IFN-γ before EAE onset ameliorated the disease course and prevented demyelination, axonal damage, and oligodendrocyte loss. The beneficial effects of IFN-γ were accompanied by PERK activation in oligodendrocytes and were abrogated in PERK-deficient animals. Our results indicate that IFN-γ activation of PERK in mature oligodendrocytes attenuates EAE severity and suggest that therapeutic approaches to activate the ISR could prove beneficial in MS