Asian Star Anchor Chain (China)

Abstract Zirconium (Zr) was doped to optimize the NH3‐SCR activity of both CeO2 and thiourea modified CeO2‐TA catalysts for comparison. Different from the promotional influence of thiourea modification on the agglomeration of CeO2, the transformation from nanoparticles to nanocubes and the formation of highly crystallized CeOSO4, Zr doping lowers the agglomeration of nanoparticles, loosens the surface morphology of catalyst and promotes the formation of Ce‐Zr solid solution. Furthermore, Zr doping exhibits a synergistic promotional effect of thiourea modification on the dispersion of Ce3+ and S6+ species on the surface of CeO2, and increases the concentrations of the surface total oxygen and chemisorbed oxygen of CeO2‐TA. Interestingly, Zr doping instead decreases the promotional effect of thiourea modification on the high‐temperature or medium/low‐temperature reducibility of catalyst, but increases both Brønsted and Lewis acid sites of CeO2‐TA by inducing the highly dispersive sulfate species rather than the CeOSO4 crystal, which might be crucial to the NH3‐SCR activity of Ce‐based catalyst.

The present paper involves a fundamental research on microdomain yield behavior of an ultrahigh strength low alloy steel with high temperature tempered bainite. The smooth cylinder specimen was took from deep water mooring chain links from the steel with the chemical composition of 0.23C–0.25Si −0.70Mn–3.55 (Cr+Ni+Mo) −0.13 (V+Nb+Ti) (mass %) ,which was quenched from 1253K and then tempered at 873K Its macroscopic yield strength is 1120MPa and the tensile strength is 1250MPa In-situ neutron diffraction measurements of loading tension have suggested that a good linear elastic deformation can be kept up to 500MPa stress, and then (200) priority non-linear elastic strain, that is the yield of crystal lattice occur at 700MPa and the (110) non-linear elastic strain was found at 800MPa. The (200) and (110) nonlinear elastic strain increases gradually when the stress was further increased, however, the (211) kept its linear elastic deformation stage as before. The sub-microstructural analysis carried out using TEM and additional determine the nature and quantitative analysis has revealed that there are three kinds of alloy carbides: (1) θ-M3C cementites with an average particle size of less than 50 nm which inside laths and lath boundaries; (2) e-M2C formed uniformly within the ferrites with a length of less than 200 nm and width of less than 20 nm; (3) ultra-fine high density MC cohered with matrix α-Fe and its particle size is about 2 nm. The whole microdomain yield behaviour of the material was possibly influenced by the fcc-MC with high density. The results of CLT (constant load), SSRT (slow strain rate) and KIscc test of the present chain in seawater solution indicate, that threshold value of SCC (stress corrosion cracking) stress exceed 0.8 tensile strength and the chain’s KIscc value is double of KIscc value of 4340 steel type parts. MC not only form strong hydrogen trap, but also slow down microdomain yield likely by means of increasing yield strength of crystal lattice, thus reduce SCC sensibility of the steel.