Effect of strain rate on microstructural evolution and thermal stability of 1050 commercial pure aluminum

Effects of strain rate on the microstructure evolution and thermal stability of1050commercial pure aluminum processed by means of split Hopkinson pressure bar(SHPB)and Instron?3369mechanical testing machine were investigated.Samples in the deformed state and after various annealing treatments at423?523K(150?250°C)for1h were characterized by TEM and hardness test.The result reveals that the samples in the deformed state were mainly composed of elongated subgrains/cells with high density of dislocations.Microstructures of the quasi-static compressed aluminum were quite stable throughout the temperature range studied,and no significant grain growth was observed.However,for the dynamic impacted one,recrystallized grains with an average grain size of4.7μm were evolved after annealing at523K(250°C)for1h.It is suggested that the annealing behavior of this dynamic deformed aluminum is a continuous process of grain coarsening,rather than the traditional discontinuous recrystallization for the quasi-static compressed aluminum.

KGmax Curves Associated With Second Generation Intact Stability Criteria for Different Types of Ships

Currently, second generation intact stability criteria are being developed and evaluated by the International Maritime Organization(IMO). In this paper, we briefly present levels 1 and 2 assessment methods for the criteria of pure loss of stability and parametric roll failure modes. Subsequently, we show the KG_(max) curves associated with these criteria. We compute these curves for five different types of ships and compare them with the curves embodied in the current regulations. The results show that the safety margin ensured by the first level-1 method of calculation for both pure loss of stability and parametric roll seems to be excessive in many cases. They also show that the KG_(max) given by the second level-1 method and by the level-2 method may be very similar. In some cases, the level-2 method can be more conservative than the second level-1 method, which is unanticipated by the future regulation. The KG_(max) curves associated with parametric roll confirm that the C11 container ship is vulnerable to this failure mode. The computation of the second check coefficient of parametric roll level 2(C2) for all possible values of KG reveals the existence of both authorized and restricted areas on the surface formed by both the draft and KG, which may replace the classical KG_(max) curves. In consequence, it is not sufficient to check that C2 is lower than the maximum authorized value(R_(PR0)) for a fixed ship's loading condition.

Microstructural Evolution, Mechanical Properties and Thermal Stability of Gradient Structured Pure Nickel

The microstructural evolution of pure nickel treated by deep rolling(DR)technique with different indent depths was investigated by means of optical microscopy and transmission electron microscopy.The surface roughness,hardness and residual stress distribution along the depth from surface were measured.Moreover,the DR-treated sample was annealed at temperatures from 300 to 700℃for 2 h.The results reveal that dislocation movements are the fundamental mechanisms of gradient grain refinement during the DR process.With increasing indent depth of the DR,the gradient microhardness on the cross section of sample significantly increases,the maximum compressive residual stress decreases,and the affecting region of residual stress increases.The results of thermal stability depict that the microstructure can be stable as temperature up to 300℃,and the abnormal grain growth and annealing twins are observed at 600℃.

Stability of NiCrAlY coating/titanium alloy system under pure thermal exposure

In this paper,NiCrAlY coating was deposited on TC4 titanium alloy using arc ion plating,and the stability of NiCrAlY coating/TC4 substrate system under pure thermal exposure was analyzed in a wide temperature range.During the thermal exposure,β→γ′→γphase transformation takes place in the NiCrAlY coating.The NiCrAlY coating phases totally decompose above the allotropic transformation temperature of TC4.The allotropic transformation ofα-Ti to β-Ti of the substrate significantly influences the stability of NiCrAlY coating/TC4 substrate system.NiCrAlY coating elements are mainly consumed by interfacial reactions below the allotropic transformation temperature of TC4.Above the allotropic transformation temperature of TC4,NiCrAlY coating elements are mainly consumed by element dissolution in β-Ti.The NiCrAlY coating totally degrades for the dissolution of coating elements in the substrate to form thickβ-Ti stabilized layer.

基于重叠网格的船舶航向稳定性数值研究

基于重叠网格技术,采用URANS粘性数值模拟方法,对标准船模KVLCC2裸船体的航向稳定性进行了数值预报。基于STAR-CCM+平台,采用重叠网格技术和切割体网格,根据SIMMAN2014提供的标准算例,对KVLCC2进行了斜航运动和纯艏摇运动的数值模拟,得到了横向力和转首力矩的历时曲线,并根据操纵性数学模型推倒出水动力导数,并计算稳定性衡准数,所有计算结果同模型试验数据吻合较好,验证了采用当前处理方法预报航向稳定性的可靠性。

冷涂烯锌涂料的制备与性能研究

首先研究了不同环氧树脂(E20、E44和E51)对环氧含锌涂层基本性能的影响,其次探究了纯薄石墨烯的添加对涂层防腐蚀性和力学性能的影响,确定了锌质量分数30%涂料体系中纯薄石墨烯的最佳添加量,最后考察了膨润土、聚脲、聚酰胺钠作为防沉体系对冷涂烯锌涂料贮存稳定性的作用。通过中性盐雾试验,并结合扫描电镜、表面电阻率、剩余锌含量和力学性能测试,制备出符合T/CHTS 10105—2023标准要求的冷涂烯锌涂料。结果表明:采用环氧树脂E44所制备的涂层基本性能最佳;加入质量分数0.5%纯薄石墨烯后,涂层的力学性能均有提升,表面电阻率≤10^(6)Ω,锌粉利用率超过80%,耐中性盐雾时间可达3000 h;添加质量分数0.9%膨润土、0.6%聚脲和1%聚酰胺钠防沉体系后,冷涂烯锌涂料可在50℃下稳定贮存60 d。

电喷雾推力器单发射点电流模型及稳定性分析

为促进对纯离子模式下电喷雾推力器的深入理解,分析了电喷雾推力器单发射点受力、供液及离子蒸发行为,建立了发射电流理论模型,明确了电压、供液装置流阻等参数对发射电流的影响规律。所得结果与现有实验数据吻合良好。基于所得模型,进而对单发射点顶端用于发射离子的凸起结构进行了瑞利稳定性分析,得到了单发射点稳定发射的电流上限,并分析了流阻对电流上限的影响。结果表明:发射电流为外加电压的二次函数,与供液装置的流阻成反比关系;纯离子模式存在一个稳定发射电流上限,超过此上限,凸起结构便会破碎;流阻越大,发射电流上限越大。

微合金化元素对纯铜热稳定性和导电性的影响

利用光学显微镜(OM)、透射电镜(TEM)和电导率测试等研究了添加微量合金化元素对4N纯铜的晶粒尺寸热稳定性和导电性的影响,分析了合金元素与基体中微量杂质元素S的相互作用。结果表明:添加微量Ti元素及微量Cr、Ni和Ag元素均可显著提高4N纯铜晶粒尺寸的热稳定性,经900℃×30 min高温处理后,Cu、Cu-Ti和Cu-Cr-Ni-Ag的晶粒尺寸分别为158.57、86.06和48.35μm,即热稳定性Cu-Cr-Ni-Ag>Cu-Ti>Cu。同时,添加微量合金化元素后纯铜的导电率仍较高,Cu、Cu-Ti和Cu-Cr-Ni-Ag导电率分别为101.87、101.64和99.98%IACS。分析认为热稳定性的提高主要与TiS相、CrS相的钉扎以及Ni和Ag固溶拖拽有关,微量Ti和Cr可与杂质S反应形成六方结构TiS相和单斜结构CrS相,且均与基体呈非共格关系,特别是CrS相较TiS相更为细小、数量更多。

纯电动商用车集成驱动桥质量对操纵稳定性影响规律的研究

为研究集成式电驱动桥纯电动商用车的操纵稳定性,利用Adams/Car建立了车企某集成式电驱动桥纯电商用车整车模型,采用国标试验方法与评价指标分别进行了蛇形试验、方向盘角阶跃试验和方向盘角脉冲试验的仿真实验,分析了方向盘输入曲线和横摆角速度变化曲线及非簧载质量对整车操纵稳定性的影响规律。研究结果表明,汽车侧向加速度峰值、横摆角速度峰值随着电动集成驱动装置质量的增加而增大,簧下质量每增加100 kg,蛇形试验工况下的最终得分降低0.915%,方向盘角阶跃试验最终得分降低0.32%,获得了非簧载质量对操纵稳定性影响的具体规律。

燃油车和纯电车混杂智能网联队列系统的节能与稳定控制

提出了一种燃油汽车和纯电动汽车混杂的异构智能网联队列系统节能策略与稳定控制方法。考虑了异质车辆动力学特征、通讯时滞和外界干扰等多重不利因素对队列稳定性的影响,建立了异质车辆队列非线性系统动力学模型和能耗模型;基于能耗成本和后退动态规划方法,推导出了单车经济车速;依据所提出的节能型车间距策略,构建了状态跟踪误差系统;基于连续时间域分布式鲁棒控制方法,给出了在干扰和信息时滞下的队列系统稳定判据。对包含4辆跟随车的混杂队列系统进行仿真测试。结果表明:在保持队列系统稳定的前提下,4辆跟随车辆节能效果分别提高1.90%、1.25%、19.11%和12.22%。

基于过滤补液方法的新型油气集输橇装置研制与应用

由于安塞油田常规转油站点,采用气液分离输送,传统工艺流程设备设施多,维护工作量大。针对这一问题,研制新型集输装置,此装置的创新设计是当流经混输泵的气液比比例高时,后置分离稳流器开始自动给混输泵补液,直到满足混输泵的气油比要求,最后经防结蜡装置处理管壁结蜡。新型油气集输橇具有自动化高、工艺性强等优点;实时监控系统运行参数及设备状态,并具有远程控制终端,相比于其他混输设备能实现无人值守状态下系统流程的自动切换,保障系统在超压、有害气体超标等异常工况下自动调整流程,解除故障。在王南作业区开展试验与运行结果表明:智能油气混输装置现场安装运行后满足混输需求,实现了输送纯液、输送纯气、油气混输、等模式。

Rosemary and Oregano Essential Oils as Natural Antioxidant to Preserve Pistachio Puree

In this study,the effect of adding essential oil from different plants on prolonging the shelf life of pistachio puree was investigated.For this purpose,Rancimat method,which is one of the accelerated shelf-life test(ASLT)methods,was used to determine the effect of oregano(OO)and rosemary(RO)essential oils on the oxidative stability of pistachio puree.Butylated hydroxyanisole(BHA)and the control sample were used for the comparison.Concentrations used for essential oils and synthetic antioxidants were 150,300 and 600 ppm and 150 ppm,respectively.The conductivity was followed at three temperatures,110,120 and 130℃,with the addition of essential oils and BHA to pistachio puree during ASLT.Pistachio puree with essential oils showed protection against the lipid oxidation process.As the temperature increased induction time was significantly decreased during ASLT(p<0.05).The same concentrations of essential oils and BHA were also added into pistachio puree to observe the change in peroxide value(PV)and free fatty acid(FFA)value under normal storage temperatures 15,25 and 40℃.The PV and FFA increase were lower in RO,OO and BHA added pistachio puree samples during 8-month storage(p<0.05).Six hundred(600)ppm of RO added sample had an antioxidative effect as much as 150 ppm BHA added sample for both ASLT and normal storage conditions.These essential oils could be used as natural antioxidants in foods with high lipid content increasing the shelf life of these products.

不同工况下养殖工船纯稳性分析

为增强养殖工船的稳性,保证其在不同工况下的安全性,基于国际海事组织(International Maritime Organization,IMO)的纯稳性丧失衡准,对极端海况下养殖工船的稳性进行计算,并分析相应影响因素。研究成果可为养殖工船纯稳性分析提供一定参考。

CsPbX_(3)(X=Br,I)@ZIF-8复合材料用于高效WLED器件

纯无机铯铅卤钙钛矿材料由于其高光致发光量子产率(PLQY)、高色纯度、可调带隙、高载流子迁移率在光电子器件中引起了广泛的关注。然而,水、氧条件下稳定性较差使其实际用途受到限制,为了提升水氧环境下的稳定性,在典型热注射法合成步骤中加入干燥的纳米粒子自组装方法合成的ZIF-8粉末使钙钛矿纳米晶体在ZIF-8孔隙中原位生长得到CsPbX_(3)@ZIF-8(X=Br,I)复合材料,该合成方法步骤简单,成本低廉,合成样品具有优异的稳定性,在空气中可以稳定2年以上,水中15 d后依然观察到明亮的荧光发射。以PMMA为基体材料制备的CsPbX_(3)@ZIF-8/PMMA(X=Br,I)复合膜具有良好的光学特性,分别制成绿光CsPbBr3@ZIF-8/PMMA膜发射峰波长为525 nm与红光CsPbI3@ZIF-8/PMMA膜发射峰波长为697 nm。以蓝光LED为光源制备成的WLED器件达到白光色度坐标为(0.3112,0.3334),色温6552 K,显色指数(CRI)为73.6。

建筑外墙抗紫外罩面清漆的研制

开发一款具有耐老化性能的罩面清漆,不仅可以起到屏蔽紫外线的功效,而且方便施工,具有极佳的便捷性与适用性。实验结果表明,实验开发的罩面清漆具有优异的耐老化性能,涂层整体抗老化性能的明显提升,紫外吸收光谱表明,UV-7751W相较于DW-123(N)在紫外波段有更宽泛的响应区间,表现出更良好的抗紫外老化性能,且复配紫外光吸收剂性能更优,其他基础涂膜性能如耐沾污性(<10%)和耐洗刷性(>10000次)远超标准,这对于长久地保持建筑物清洁自然,延长建筑物的翻新周期,节约自然资源至关重要,符合新时代的发展要求。

纯电动商用车底盘协同控制器开发

文章致力于研究开发纯电动商用车底盘的协同控制器,通过车辆动力学建模和深度学习与比例-积分-微分(PID)控制技术的结合,设计了转向制动协同控制器,通过仿真验证了控制器的有效性和稳定性。仿真结果显示,纯电动商用车的操控性和安全性得到了良好提升,为商用车的电动化发展提供了支持。

Ultra-Pure Ferritic Stainless Steels-Grade,Refining Operation,and Application

The grades of ultra-pure ferritic stainless steels, especially the grades used in automobile exhaust system, were reviewed. The dependence of properties on alloying elements, the refining facilities, and the mechanism of the reactions in steel melts were described in detail. Vacuum, strong stirring, and powder injection proved to be effective technologies in the melting of ultra-pure ferritic stainless steels. The application of the ferritic grades was also briefly introduced.

Effect of cold-rolled annealing processes on microstructure and properties of ultra-pure ferritic stainless steel

In this study, the influence of annealing processes for cold-rolled sheets on the microstructure and mechanical performance of ultra-pure 430 ferritic stainless steel was investigated. Thermo-Calc calculation, organization observation, SEM detection,and tensile tests were used to discern the optimal annealing process. It is found that the microstructure is made up by the fine and uniform recrystallized ferritic grains after annealing. The optimum annealing process for ultra-pure 430 stainless steel is 950 ℃ for 90 s. After annealing, the stainless steel can obtain the optimum microstructure,recrystallization texture, and mechanical properties.

Certification of a Multicomponent Reference Material from Natural Gas Mixture by Gravimetry and Dual GC-FID/TCD System

Natural gas (NG) is one of the most important sources of energy for industrial and domestic consumption in the present era because it is cheap and free from sulfur impurities. Therefore, accurate and precise measurement of its composition is of fundamental importance for trade reasons. To improve the quality of NG gas measurements, certified reference materials (CRMs) should be used for calibration of measuring equipment in order to ensure the traceability of the measurement results to the SI units. For the traceability purpose, a multicomponent natural gas mixture was prepared gravimetrically as a reference material according to ISO 6142 from pure helium, hydrogen, n-pentane, i-pentane, n-butane, i-butane, propane, ethane, hexane, methane and nitrogen. The preparation was done in two dilution steps in 5 L aluminum cylinders. The calculated mole fractions and associated uncertainties of natural gas components were verified by a dual GC-FID/TCD system in accordance with ISO 6143 calibrated by a series of primary gas mixtures (CRMs) produced by an NMI. The results obtained by gravimetry and by GC measurements have been checked for compatibility as required by ISO 6142 and were found in very good agreement. Details of the preparation and calculation of the mole fractions and uncertainties of all gas components are explained in this article.

经导管主动脉瓣置换术治疗单纯主动脉瓣反流的临床疗效分析及经验

目的探讨使用自膨胀式瓣膜行经导管主动脉瓣置换术(TAVR)在单纯主动脉瓣反流(PAR)患者中的疗效,总结这一术式的初步经验。方法纳入2022年4月至2023年5月武汉亚心总医院和武汉亚洲心脏病医院使用TaurusElite经导管主动脉瓣系统实施TAVR的PAR患者共20例,收集并分析患者的临床基线资料、超声心动图资料及术后住院期间和出院后30 d随访资料。结果患者的平均年龄为(73.5±5.5)岁,平均美国胸外科医师协会(STS)评分(8.7±3.6)%,术前重度主动脉瓣反流16例(16/20)。经TAVR治疗后,手术成功20例(20/20),单一瓣膜器械成功19例(19/20,瓣中瓣1例)。术后30 d随访结果显示,20例患者未出现死亡、致残性脑卒中、心肌梗死及转外科事件,术后主动脉瓣残余反流程度均为无或者微量,手术效果理想。结论经过严格的病例筛选及规范的手术标准化操作,使用自膨胀式瓣膜行TAVR治疗PAR患者的可行性高,早期临床结果良好,可进一步推广应用;对于所归纳总结的术式经验,可做进一步临床验证。