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《中国有色金属学会会刊》2020,30(5):1238-1248
The energy absorption capacity of the Al5083 thin-walled tube produced by parallel tubular angular pressing (PTCAP) process was evaluated. Also, microstructure, mechanical properties, and anisotropy coefficients were studied in the peripheral and axial directions. Results showed that values of energy absorption decreased with processing pass increasing and the values for the unprocessed, first and second passes were obtained to be 167, 161.4 and 160.7 J, respectively. The differences between the simulation results for the energy absorption values and their experimental values for the unprocessed, the first and the second PTCAP passes samples are about 5%, 10%, and 13%, respectively. The energy absorption capacity was related to the anisotropy coefficient and microstructure. The results demonstrated that grain refinement occurred and ultimate tensile strength (UTS) and microhardness after the first and second PTCAP passes were enhanced, while the increase rate in the first pass was much severer. Also, by applying PTCAP, the deformation modes were altered, such that the deformation mode of the annealed tube was quite symmetrical and circular while for the first and second passes there have been triple and double lobes diamond. The results of the numerical simulation for the deformation mode of the annealed and PTCAPed tubes were consistent with the experimental results. The deformation mode of tubes is dependent on their mechanical properties and variation of the mechanical properties during PTCAP process. 相似文献
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《Ceramics International》2022,48(5):6166-6176
This study coated the surface of irregularly shaped 5-μm boron particles with TiO2 nanoparticles to improve the ignition performance of the boron. A simple and inexpensive chemical method was used to coat the surface of boron with TiO2. Five different samples of boron coated with TiO2 nanoparticles were obtained by varying the concentration of Ti precursor. Surface structures were analyzed using different characterization techniques, which showed the formation of nanocrystalline TiO2 nanoparticles over the boron surface. The nanoparticles of TiO2 were well dispersed over the boron surface, and exhibited strong interfacial contact with the boron. The oxidation of boron and boron coated with TiO2 was analyzed by thermogravimetric technique in an air atmosphere from room temperature to 1000 °C. Results revealed that the oxidation of boron started at a temperature approximately 162 °C lower after coating with TiO2. The ignition behavior of the boron and boron coated with TiO2 particles was studied using a shock tube. The results of the shock tube experiments demonstrated the TiO2 coated boron had a shorter ignition delay time than the bare boron. An approximate 35% reduction was observed in the ignition delay time of boron after coating with TiO2 nanoparticles, showing its potential value in high energy density fuels. 相似文献
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国内外对多相流管输体系中水合物沉积的研究虽然很多,但水合物沉积机理仍有待进一步研究。本文根据水合物沉积实验开展条件的不同,将多相流管输体系分为气体主导体系、油基体系、部分分散体系、水主导体系,总结了各体系的水合物沉积的主要机理,并提出了未来的发展方向。管输体系中水合物沉积机理包括水润湿沉积表面、水合物颗粒聚并、水合物的管壁膜生长、水合物颗粒的管壁粘附和水合物的颗粒着床沉积等。大多数学者认为:水合物的管壁膜生长是气体主导体系水合物沉积的主要机理;油基体系水合物沉积的主要机理是水合物颗粒的着床沉积;而部分分散体系和水主导体系的水合物沉积机理尚无统一定论,需进一步研究。多相流管输体系中水合物沉积研究未来的发展方向如下。①搭建全透明的流动环路,观测水合物在管路内实际的形成过程及沉积过程,对水合物沉积机理进行深入研究。②量化研究油水分层、油包水(或水包油)乳状液、自由水层对水合物沉积、堵塞的影响。③对于气体主导体系,除环状流和分层流外,有必要对段塞流、气泡流等其他常见的流型下沉积机理进行研究,重点在于开发一个综合模型来描述水合物沉积过程。④对于水主导体系,水合物形成过程出现的油水破乳的具体机理应是未来水合物沉积过程进行定量研究的方向。⑤国内外对垂直管、弯管及管阀件处水合物沉积堵塞理论研究较少,未来应着重这方面。 相似文献
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如何进行非开挖施工管线探测一直是个大难题,本文简要介绍了福州市非开挖施工管线铺设现状,分别从顶管施工管线测量、拉管施工管线探测两方面,阐述了非开挖施工管线探测的技术方法。在福州市地下管线数据库近几年的更新维护过程中,总结了一些非开挖施工管线的探测经验。 相似文献
47.
This work concerns the effect of gas phase properties on incipient flooding in counter-current gas–liquid two-phase flow in small diameter inclined tubes (D < 10 mm). The aim is to propose generalized correlations that can be used to predict incipient flooding in small diameter tubes. Experiments were performed in a 7 mm glass tube and at two inclination angles, i.e. 30 and 60° from the horizontal, using water as liquid phase and atmospheric air, He and CO2 as gas phase. Previously proposed correlations for flooding prediction ( Pantzali et al., 2008) were suitably adjusted to incorporate the effect of gas phase properties. It has been proved that the flooding curves calculated using the proposed correlations are in good agreement with both the results of the present study and relevant literature data. 相似文献
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在工业生产过程中,列管式换热器是运用比较广泛的换热装置。由于设备结构和工艺条件存在差别,在使用过程中,会发生各种形式的故障和失效。针对列管式换热器常见的故障形式,分析故障产生的原因,提出处理的方法与意见,为列管式换热器的使用、维护和检修等提出建议。 相似文献
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以天溪煤制油分公司灰熔聚气化炉的生产运行为例,分析了对入炉原料煤的指标要求,介绍了灰熔聚气化炉设备结构及流化床的物料循环机理,分析了灰熔聚气化炉在不同的分布板气速、中心管气速、氧气浓度条件下的运行状况。工业运行结果表明,首套加压灰熔聚气化炉生产运行稳定,且能满足相关地区就地取材的要求。 相似文献