Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 2024

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Microstructure, Compressive Properties and Oxidation Behaviors of the Nb-Si-Ti-Cr-Al-Ta-Hf Alloy with Minor Holmium Addition

Wang Qiaoli, Xiao Yinan, Wu Di, Yang Fang, Sheng L. Y.

Archives of Metallurgy and Materials

2024

Vol. 69, iss. 1

181--187

In the present research, the Nb-Si-Ti-Cr-Al-Ta-Hf alloys with different Ho addition were prepared. Their microstructure, compressive properties and oxidation behaviors were investigated preliminarily. The results exhibit that the Nb-Si-Ti-Cr-Al-Ta-Hf alloy has coarse microstructure which is mainly composed of Nb solid solution, Nb5Si3 and Ti5Si3 phases. The minor Ho addition could refine the microstructure and suppress the precipitation of Ti5Si3 phase. Moreover, the Ho addition also leads to the formation of Ho2Hf2O7, which prefers to precipitate along the Nbss/Nb5Si3 phase interface. Compared with the Nb-Si-Ti-Cr-Al-Ta-Hf alloy, the minor Ho addition improves the room-temperature and high-temperature compressive properties of the alloy. Its room-temperature compressive strength and ductility obtain the maximum value of 1825 MPa and 16.5% when the Ho content is 0.1 at.%. Moreover, its best compressive strength at 873 K, 1273 K and 1473 K is 1495 MPa, 765 MPa and 380 MPa, respectively, when the Ho addition is 0.1 at.%. The oxidation behavior of the Nb-Si-Ti-Cr-Al-Ta-Hf alloy is diversified with the Ho addition. The oxidation rate of the alloy with 0.1 at.% Ho addition is the lowest while the alloy with 0.2 at.% Ho addition is the highest. Therefore, the 0.1 at.% Ho would be the appropriate content for the Nb-Si-Ti-Cr-Al-Ta-Hf alloy.

Exploration and Improvement of Room Temperature Properties for Organosilicon Slag Riser

Lu Jljun, Zhong Zhuofan, Hu Youngluan, Wu Di, Wang Huafang

Archives of Foundry Engineering

2024

Vol. 24, iss. 2

35--43

Organosilicon slag, generated as a waste product from organosilicon monomer production, had limited options for resource utilization. Previous experiments utilized recovered organosilicon slag to partially replace heating materials in preparing exothermic insulating risers. However, the incorporation of organosilicon slag led to specific issues in the risers including low compressive strength, high resin addition requirement and easy ignition during drying. In order to address these problems, this study analyzed the effects of resol resin parameters and organosilicon slag on the ambient temperature properties of heating insulating risers through single-factor experiments. In addition, adjustment was made to the drying process and an optimal preparation scheme was determined via orthogonal experiments. The purpose of the study was to prepare risers with reduced resin content, increased organosilicon slag addition and adequate compressive strength. Results showed that selecting a resin viscosity of about 170 mPa.s and resin addition of about 13% allowed for relatively good compressive strength and air permeability with less resin required. Additionally, an organosilicon slag addition of 18-21% and particle size under 30 mesh(550 μm) was beneficial for improving compressive strength. Adjusting the drying process to a two-step heat preservation approach (180°C for 25 min, then 130°C for 35 min) slightly decreased compressive strength compared to the original process; nevertheless, it improved air permeability and prevented the risers from igniting spontaneously during subsequent drying. The optimized preparation scheme determined through orthogonal experiments involved 150 mPa.s resin viscosity, 14% resin addition, 21% organosilicon slag addition and slag particle size less than 30 mesh (550 μm). This yielded a compressive strength of 4.21MPa and air permeability of 75.6, exceeding the standard of the exothermic insulating riser: GB/T13040-2017.