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Interface reaction during titanium alloys investment casting by residue gas in ceramic mold

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Rare Metals 2019年第4期38卷 327-335页

作者： ya-meng wei Zhi-Gang Lu Xin-Yi Li Xin Guo Department of Mechanical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084 China Academy of Opto-Eletronics Chinese Academy of Sciences Beijing 100094 China

The chemical reaction between mold material and titanium melt during investment casting was studied intensively. However, the in fluence of residue gas in ceramic mold on interface reaction remains unclear. In this investigation, the effect of residue gas in Y2O3-silica sol shell mold on interface reaction during Ti-6A1-4V alloy investment casting was investigated. Two groups of shell molds were prepared by adding different kinds of pore formers, i.e., spherical starch particles or nylon fibers, respectively. Ti-6Al-4V alloy was cast under vacuum by gravity casting through cold crucible induction melting (CCIM) method. Porosity of different shell molds was measured based on Archimedean method. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to characterize the micromorphology and composition of the reaction area, respectively. White light interferometer (WLI) was used to obtain the surface topography of the shell mold. The results show that the direct chemical reaction is very weak for all specimens. The release of residue gas in closed pores is the key factor influencing surface defects. However, open pores make nearly no difference on the interface reaction.

关键词： Titanium alloy Investment casting Residue gas Y2O3: Silica sol

Reaction between Ti–6Al–4V and Y_2O_3–SiO_2 based face shell for investment casting

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Rare Metals 2016年第12期35卷 901-908页

作者： ya-meng wei Zhi-Gang Lu Guang-Peng Wu Xing-Quan Long Department of Mechanical Engineering Tsinghua University State Key Laboratory of Tribology Tsinghua University Guizhou Anji Aviation Investment Casting Co. Ltd.

The pH value and viscosity of Y2O3-SiO2 （Y-Si） slurry made by Y2O3 powders and silica sol for the face coat of Ti-6Al-4V investment casting were measured. The thermal behavior of the shell made by the Y-Si face coat system was investigated by differential scanning calorimeter （DSC）, thermal gravimetric （TG） analysis combined with mass spectrometry （MS）, and the phase transformations were determined by X-ray diffraction （XRD）. Hot strength, residual strength, linear expansion coefficient, and wearing resistance performance of the shell were also tested. The microstructure and elements distri- bution of the interaction layer were studied by scanning electron microscope （SEM） and energy-dispersive spectrometer （EDS）, respectively. The microhardness tester was applied for the microhardness. The results showed that the slurry was stable for at least 60 h. A very small amount of YZrO3 was formed below 1050℃ and Y2SiO5 was formed around 1450℃. The shell made by Y-Si system had good mechanical property which could reduce cracks during the procedure of dewaxing and inclusions during pouring. Some Al volatilized from the melt, permeated the surface of the face coat shell, and formed the black reaction layer, which blocked the permeation of O so that O penetration was limited to 5μm. The depth of Si penetration was about 60 μm. The hard layer was also around 60 μm.

关键词： Investment casting Titanium alloy Silica sol Yttrium oxide Interface reaction

Effect of SiO_2 concentration in silica sol on interface reaction during titanium alloy investment casting

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China Foundry 2018年第1期15卷 23-30页

作者： ya-meng wei Ke-hui Hu Zhi-gang Lu Department of Mechanical Engineering Tsinghua Universit Beijing 100084 China State Key Laboratory of Tribology Tsinghua University Beijing 100084 China

Using silica sol as a binder for titanium investment casting is very attractive due to its good stability and reasonable cost as compared with yttrium sol and zirconium sol. However, the mechanism of interface reaction in the related system remains unclear. In this investigation, the interface reaction between Y_2O_3-SiO_2(YSi) shell mold and titanium alloys was studied. A group of shell molds were prepared by using Y_2O_3 sand and silica sol with different contents of SiO_2. Ti-6Al-4V alloy was cast under vacuum by gravity casting through cold crucible induction melting(CCIM) method. Scanning electron microscopy(SEM) and energy dispersive x-ray spectroscopy(EDS) were employed to characterize the micromorphology and composition of the reaction area, respectively X-ray photoelectron spectroscopy(XPS) was used to confirm the valence state of relevant elements. White ligh interferometer(WLI) was used to obtain the surface topography of Y-Si shells. The results show that the thickness of reaction layers is below 3 μm when the SiO_2 content of silica sol is below 20 wt.%. Whereas, when the SiO_2 content increases to 25 wt.%, the thickness of the reaction layer increases sharply to about 15 μm. There is a good balance between chemical inertness and mechanical performance when the SiO_2 content is between 15 and 20 wt.%. Moreover, it was found that the distribution of SiO_2 and the roughness at the surface of the shell are the key factors that determine the level of reaction.

关键词： titanium alloy investment casting Y2O3 silica sol surface roughness

Joint Probabilistic Scheduling and Resource Allocation for Wireless Networked Control Systems

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 258-260页

作者： meng Zheng Lei Zhang wei Liang IEEE the State Key Laboratory of Robotics and the Key Laboratory of Networked Control Systems Shenyang Institute of Automation Chinese Academy of Sciences the University of Chinese Academy of Sciences

Dear Editor,This letter presents a joint probabilistic scheduling and resource allocation method(PSRA) for 5G-based wireless networked control systems(WNCSs). As a control-aware optimization method, PSRA minimizes the linear quadratic Gaussian(LQG) control cost of WNCSs by optimizing the activation probability of subsystems, the number of uplink repetitions, and the durations of uplink and downlink phases. Simulation results show that PSRA achieves smaller LQG control costs than existing works.

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习近平人民观与新时代十年伟大变革

延安大学学报（社会科学版） 2023年第5期45卷 5-10,F0002页

作者：孟亚伟西藏民族大学马克思主义学院陕西咸阳712082

习近平人民观经历了积极倡导、努力践行的过程,新时代十年伟大变革也经历了全面布局、持续推动的过程,二者实质是理论和实践的关系,有其内在的关联性、互动性和共生性,是相互影响、共同推进、彼此成就的。习近平新时代中国特色社会主义... 详细信息

习近平人民观经历了积极倡导、努力践行的过程,新时代十年伟大变革也经历了全面布局、持续推动的过程,二者实质是理论和实践的关系,有其内在的关联性、互动性和共生性,是相互影响、共同推进、彼此成就的。习近平新时代中国特色社会主义思想的理论底色是人民观,认清十年前的形势任务是理解新时代十年伟大变革的关键,其理论和实践的关联性决定了相互影响。习近平人民观具有丰富的内涵和完整的体系,新时代十年伟大变革缘于践行习近平人民观,其理论和实践的互动性决定了共同推进。“两个确立”是人民的共同心愿,“三件大事”是人民的伟大胜利,其理论和实践的共生性决定了彼此成就。

关键词：人民观伟大变革内在关系 “两个确立” “三件大事”

一类具有时滞和领导者的二阶多智能体系统的一致性

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重庆师范大学学报（自然科学版） 2013年第5期30卷 66-70页

作者：孟亚伟杨志春重庆师范大学数学学院重庆400047

研究了一类具有时滞和领导者的二阶多智能体系统在静态和动态拓扑网络中的一致性。首先运用代数图论描述此类多智能体系统的数学模型,然后借助于图的连通性质和平衡图代数性质,并结合Lyapunov泛函方法和矩阵不等式,得到系统达到一致性... 详细信息

研究了一类具有时滞和领导者的二阶多智能体系统在静态和动态拓扑网络中的一致性。首先运用代数图论描述此类多智能体系统的数学模型,然后借助于图的连通性质和平衡图代数性质,并结合Lyapunov泛函方法和矩阵不等式,得到系统达到一致性的充分必要条件,即当系统的参数满足β/α>γλ/2+1/λ,且时滞上界τ充分小时,在固定拓扑网络中领导者结点r全局可达与系统一致是等价的。对于切换拓扑情形的多智能体系统一致性有类似结论。

关键词：时滞 Lyapunov-Razumikhin定理多智能体系统一致性

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有机硅表面活性剂复配体系下的泡沫性能

消防科学与技术 2020年第4期39卷 510-512页

作者：孟亚伟郭宗昌中国民用航空飞行学院四川广汉618307

对有机硅表面活性剂、发泡剂、稳泡剂等5种试剂运用正交实验法开展泡沫性能筛选实验。采用自主设计的机械臂振荡装置测定该复配体系的发泡倍数和25%析液时间。采用自主设计的泡沫耐热性测定装置测定该复配体系的热稳定性时间。正交实验... 详细信息

对有机硅表面活性剂、发泡剂、稳泡剂等5种试剂运用正交实验法开展泡沫性能筛选实验。采用自主设计的机械臂振荡装置测定该复配体系的发泡倍数和25%析液时间。采用自主设计的泡沫耐热性测定装置测定该复配体系的热稳定性时间。正交实验设计为5因素4水平。实验结果表明:有机硅表面活性剂、发泡剂和稳泡剂产生了较好的协同作用,复配体系的25%析液时间较单一有机硅表面活性剂提高了10倍以上。对该复配体系的发泡倍数、25%析液时间、泡沫热稳定时间综合分析发现:当Si-4903、APG、BS-12、黄原胶、6501质量浓度比为10∶20∶10∶1∶1时泡沫性能最好。

关键词：有机硅表面活性剂正交实验法发泡倍数 25%析液时间泡沫热稳定性

Physical Layer Security Scheme With AoI-Awareness for Industrial IoT Based on Covert Communications

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 276-278页

作者： yaping Li Zhi-Xin Liu Jia-wei Su ya-Zhou Yuan the Key Laboratory of Industrial Computer Control Engineering of Hebei Province Yanshan University

Dear Editor,Industrial Internet of things(IIoT) is a typical application of cyberphysical system(CPS). In the IIoT, wireless communication is an inevitable trend to replace the deployment-limited wired transmission for cases with large-scale and mobile devices. However, wireless communication gives rise to critical issues related to physical security, such as malicious detections and attacks [1].

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卤代烷替代型机载手持式灭火器研究进展

消防科学与技术 2017年第7期36卷 983-986页

作者：魏建龙贾旭宏魏中许孟亚伟中国民用航空飞行学院四川广汉618307

通过对灭火性能、ODP、GWP、ALT、NOAEL值等几个重要指标的综合考察,发现水成膜泡沫、气溶胶、惰性气体、细水雾、卤化碳是未来机载灭火器中主要的Halon替代品。对比Halon替代物与Halon 1211/1301的相关性能,认为手持式水成膜泡沫灭火... 详细信息

通过对灭火性能、ODP、GWP、ALT、NOAEL值等几个重要指标的综合考察,发现水成膜泡沫、气溶胶、惰性气体、细水雾、卤化碳是未来机载灭火器中主要的Halon替代品。对比Halon替代物与Halon 1211/1301的相关性能,认为手持式水成膜泡沫灭火器和卤化碳灭火器可作为哈龙灭火器替代品的研究方向。介绍水成膜泡沫灭火器和卤化碳灭火器应用于飞行器需要满足的各项要求,分析其研究前景。

关键词：卤代烷替代品灭火剂灭火器