Oxidation behavior of 4774DD1 Ni-based single-crystal superalloy at 980℃ in air

The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.

Effect of acupuncture on inflammatory cytokines expression of spastic cerebral palsy rats

Objective:To To investigate the effect of acupuncture on the tumor necrosis factor- α(TNF-α),interleukin-6(IL-6),C-reactive protein(CRP),nitric oxide synthase(NOS) content and muscular tension of spasticity cerebral palsy rat model.Methods:The rats with spastic cerebral palsy were randomly divided into the control group,model group and acupuncture group.After successful modeling,the muscular tension and the content of TNF- α,IL-6,CRP.NOS were measured.Results:The serum TNF- α,IL—6,CRP,NOS content were significantly decreased in the acupuncture group(P<0.05).The low and high shear viscosity of whole blood of the acupuncture group were significantly lower than the control group and the model group(P<0.05).The erythrocyte electrophoresis indexes in the acupuncture group were significantly lower than that in the model group and the control group(P<0.05).Acupuncture significantly reduced the muscular tension of spastic cerebral palsy rat and increased the active extent in the paralytie extremity(P<0.05),but it could not be restored to normal level.Compared with the control group,the difference had significant(P<0.05).Conclusions:Acupuncture treatment can inhibit the release of inflammatory cells after brain injury,then reduce immune injury,relieve muscle spasms and reduce muscular tension.