To inhibit the interfacial(displacement)reaction between Hf and Al elements in the DZ125 superalloy and the Al_(2)O_(3) and SiO_(2) in the Al_(2)O_(3)-based ceramic shell,rare-earth oxides(La_(2)O_(3) and Y_(2)O_(3))w...To inhibit the interfacial(displacement)reaction between Hf and Al elements in the DZ125 superalloy and the Al_(2)O_(3) and SiO_(2) in the Al_(2)O_(3)-based ceramic shell,rare-earth oxides(La_(2)O_(3) and Y_(2)O_(3))were used as dopants into the shell.The effects of dopant types and contents(2 wt%,5 wt%and 8 wt%)on the wettability and interfacial reaction were investigated using the sessile-drop experiment,and the reaction products were analyzed by X-ray diffraction(XRD),a scanning electron microscope(SEM),an electron probe microanalyzer(EPMA)and X-ray photoelectron spectroscopy(XPS),to clarify the mechanism of dopants in the interracial reaction.The results show that increasing the Y_(2)O_(3) doping content(2 wt%-8 wt%)reduces the surface porosity from 22.39%to 13.43%,and decreases the surface roughness from 3.25 to 2.28μm,which enhances the packing density of the shell surface.In the sintering process(1223 K,2 h),both La_(2)O_(3) and Y_(2)O_(3) dopants react with SiO_(2),forming La_(2)Si_(2)O_(7) and Y_(2)SiO_(5) on the shell surface.During the interfacial reaction process(1823 K,40 min),La_(2)Si_(2)O_(7) decomposes and reacts with Al_(2)O_(3) and HfO_(2),resulting in the formation of SiO_(2)·HfO_(2)·La_(2)O_(3) and Al_(2)O_(3)·HfO_(2)·La_(2)O_(3) ternary composite oxides within the reaction products.At 8 wt%La_(2)O_(3) dopant content,the interfacial reaction is exacerbated,resulting in the uneven wettability.Y_(2)SiO_(5) further reacts with Al_(2)O_(3) and SiO_(2) to form SiO_(2)·Al_(2)O_(3)·Y_(2)O_(3) ternary composite oxides,while Y_(2)O_(3) combines with Al_(2)O_(3) to form Al_(5)Y_(3)O_(12)(VAG),which stabilizes the oxides within the shell and inhibits the interfacial reaction,and significantly improves the surface quality of the DZ125 superalloy.As the Y_(2)O_(3) dopant content increases(2 wt%-8 wt%),the wetting angle increases from 97.8°to 110.6°.展开更多
Shell是用户访问操作系统的接口。Shell开发在Windows CE操作系统开发中占据一定的重要性。对Windows CE Shell进行了概述,并通过建立Shell模型,讲述如何自定制Windows CE Shell和定制Shell必须注意的问题,对Windows CE Shell的定制进...Shell是用户访问操作系统的接口。Shell开发在Windows CE操作系统开发中占据一定的重要性。对Windows CE Shell进行了概述,并通过建立Shell模型,讲述如何自定制Windows CE Shell和定制Shell必须注意的问题,对Windows CE Shell的定制进行深入研究。展开更多
基金Project supported by the National Natural Science Foundation of China(52374292)the China Baowu Low Carbon Metallurgy Innovation Foundation(BWLCF202309)the Natural Science Foundation of Changsha(KQ2208271)。
文摘To inhibit the interfacial(displacement)reaction between Hf and Al elements in the DZ125 superalloy and the Al_(2)O_(3) and SiO_(2) in the Al_(2)O_(3)-based ceramic shell,rare-earth oxides(La_(2)O_(3) and Y_(2)O_(3))were used as dopants into the shell.The effects of dopant types and contents(2 wt%,5 wt%and 8 wt%)on the wettability and interfacial reaction were investigated using the sessile-drop experiment,and the reaction products were analyzed by X-ray diffraction(XRD),a scanning electron microscope(SEM),an electron probe microanalyzer(EPMA)and X-ray photoelectron spectroscopy(XPS),to clarify the mechanism of dopants in the interracial reaction.The results show that increasing the Y_(2)O_(3) doping content(2 wt%-8 wt%)reduces the surface porosity from 22.39%to 13.43%,and decreases the surface roughness from 3.25 to 2.28μm,which enhances the packing density of the shell surface.In the sintering process(1223 K,2 h),both La_(2)O_(3) and Y_(2)O_(3) dopants react with SiO_(2),forming La_(2)Si_(2)O_(7) and Y_(2)SiO_(5) on the shell surface.During the interfacial reaction process(1823 K,40 min),La_(2)Si_(2)O_(7) decomposes and reacts with Al_(2)O_(3) and HfO_(2),resulting in the formation of SiO_(2)·HfO_(2)·La_(2)O_(3) and Al_(2)O_(3)·HfO_(2)·La_(2)O_(3) ternary composite oxides within the reaction products.At 8 wt%La_(2)O_(3) dopant content,the interfacial reaction is exacerbated,resulting in the uneven wettability.Y_(2)SiO_(5) further reacts with Al_(2)O_(3) and SiO_(2) to form SiO_(2)·Al_(2)O_(3)·Y_(2)O_(3) ternary composite oxides,while Y_(2)O_(3) combines with Al_(2)O_(3) to form Al_(5)Y_(3)O_(12)(VAG),which stabilizes the oxides within the shell and inhibits the interfacial reaction,and significantly improves the surface quality of the DZ125 superalloy.As the Y_(2)O_(3) dopant content increases(2 wt%-8 wt%),the wetting angle increases from 97.8°to 110.6°.
文摘Shell是用户访问操作系统的接口。Shell开发在Windows CE操作系统开发中占据一定的重要性。对Windows CE Shell进行了概述,并通过建立Shell模型,讲述如何自定制Windows CE Shell和定制Shell必须注意的问题,对Windows CE Shell的定制进行深入研究。
