ChemInform Abstract Up to 3.5 wt.% Nb are shown to reduce the Na2SO4-induced hot corrosion resistance of GMR-235D, a superalloy containing Nb as a strengthening element. From the experimental results it is suggested that Nb addition alters the hot corrosion process of GMR-235D from basic to acidic fluxing. This behavior is explained in terms of formation of Nb2O5 and an increase of the Mo activity by Nb.

Based on the analysis and design idea, we use the finite element method to evaluate the dangerous position of the conical shell opening structure, select the stress concentration coefficient of the opening as the research object, analyze the influence of different opening angle and with/withput a connecting pipe on it, and seeks the optimal design of the conical shell opening. The results show that the nozzle has a certain weakening effect on the stress concentration of the opening, and when the opening angle (the angle between the center line of the opening and the generatrix of the conical shell) is around 90° , the nozzle has a more significant strengthening effect on the structure. It also shows when the opening rate is fixed, the stress concentration coefficient of the opening decreases first and then increases with the increase of the opening angle, and when the opening angle is in the range of 80 ° to 110 ° , the stress concentration coefficient is the smallest between 2 to 3.

The laser cladding technology was used to prepare the Ti / TiB2 composite coating on the surface of Ti600, and the microstructure and performance test results of the coating obtained under different laser specific energy conditions were analyzed. Studies have shown that the laser cladding coating and the substrate have achieved a good bond, and TiB2 has formed into cellular TiB2 after melting, and further solid solution becomes a whisker structure. The diffused TiC and TiN nuclei in the middle of the coating were fully grown and developed a dense dendrite structure with TiB2 particles. A dual-phase structure of granular TiB2 and many lamellar structures was formed under the coating. When the laser specific energy is 20 kJ / cm2, the coating reaches the highest microhardness of 990HV, nearly 2.5 times the hardness of the substrate. The amount of wear shows a monotonic decrease with the increase of the specific energy of the laser, and the average friction coefficient shows a monotonous decrease as the specific energy of the laser increases.