实型铸造干砂振动紧实性能的研究

通过对实型铸造干砂振动填充紧实中的振动方向、维数、频率、加速度及干砂种类等诸多影响要素的测定实验，研究了实型铸造振动紧实干砂的性能。     

石灰石旧砂回收使用的研究

研究了石灰石旧砂回收的几个方案,着重试验了影响旧砂干强度和保存性几个因素.结果表明,在旧砂混制中加入碳酸钠和水,在保证干强度前提下能显著改善旧砂混制后的保存性,满足生产要求.     

用β淀粉做砂芯主粘结剂的研究

研究了在淀粉砂中添加膨润土。石墨粉和磷酸二氢钠后的性能，最佳配比和烘干工艺，研究表明，在淀粉砂中添加ＮａＨ２ＰＯ４可提高淀偻砂的湿强度和干强度及抗吸湿性，能够满足铸铁生产制芯的要求。     

实型铸造用振实台激振参数与干砂流动性态、充填性及紧实度关系的实验研究

：干砂的充填及紧实是实型铸造工艺技术中的关键要素。本文着重研究了实型铸造工艺中振动紧实台振动参数与砂体流动性、充填性及紧实度的特性关系。结果表明,振动紧实台激振方向、频率和强度及砂箱结构的合理确定将有利于模样凹部的有效充填及提高砂体紧实度。     

实型铸造用振实台激振参数与干砂流动性态,充填性紧实度关系的实 …

干砂的充填及紧实是实型铸造工艺技术中的关键要素,本文着重研究了实型铸造工艺中振动紧实台振动参数与砂体流动性、充填性及紧实度的特性关系。结果表明,振动紧实台激振方向、频率和强度 及砂箱结构的合理确定将有利于模样凹部的有效充填及提高砂体紧实度。     

国内发展干砂消失模铸造技术的关键问题

根据国内外的研究应用情况及作者几年来的研究，提出了在国内大规模应用干砂消失模铸造必须解决的几个关键技术问题。     

消失模铸造充型阶段干砂型壁的稳定准则

对干砂的抗剪强度进行了研究，认为型砂存在咬合强度。基于含有咬合强度的摩尔—库仑抗剪强度包线，研究了在消失模铸造充型阶段，保持干砂—气隙界面、干砂—金属液界面稳定的力学关系式，结果表明，干砂。气隙界面不可能发生朗肯被动破坏，只可能发生朗肯主动破坏，其后果是铸型坍塌。与此相反，干砂。金属液界面不可能发生朗肯主动破坏，只可能发生朗肯被动破坏，其后果是铸件增厚或胀箱。据此提出了避免坍塌缺陷的临界气隙高度和避免胀箱缺陷的许可铸件高度概念，并讨论了各种工艺因素对它们的影响。     

消失模铸造工艺的发展和研究现状

评述了消失模铸造工艺的发展历程及目前国内外的主要研究方向。针对近年来发展起来的干砂振动造型方面的研究成果进行了重点总结。     

"桂林1号"湿型强化工艺取代粘土砂干型及水玻璃砂和树脂砂型的应用

介绍了桂林1号湿型强化工艺取代粘土砂干型及水玻璃砂和树脂砂型生产铸铁件、铸钢件的几个应用实例,回答了湿型代替干型所遇到的几个技术问题.     

干砂对EPS模样垂直向下盲孔充填性的研究

研究了干砂对ＥＰＳ模样中垂直向下盲孔的充填性能,主要工艺因素,如管径、管口深度、干砂粒形、振动方向、振动维数、振动频率、振动加速度等对垂直向下盲孔充填高度的影响。初步探讨了干砂对垂直向下盲孔充填的机理。     

Numerical simulation on rapid melting and nonequilibrium solidification of pure metals and binary alloys

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Fe-Mo合金高温硫化产物中的固态反应及传质

以XRD、SEM/WDS和TEM分析结果为依据,对Fe-Mo(Mo=20%～57%)二元合金在硫蒸气中(PS2=1～50kPa)高温硫化产物层的相组成及膜层中的有关固态反应进行了探讨,绘出了可能的稳定相图,分析了主要硫化产物的缺陷结构特点及其对硫化传质的影响.认为Fe、Mo混合硫化物中的缺陷密度较高,对传质的阻力较小;而MoS2层缺陷密度小,对阻止硫化反应物传质起主要作用.     

消失模铸造工艺因素对液态金属充型能力的影响

综述消失模铸造金属液充型能力的研究成果,从传热、传质角度分析各工艺因素对充型能力的影响.消失模铸造金属液的充型过程是由泡沫模样的热分解速率及分解产物的逸出速率之间的动平衡所控制的,凡是影响传热、传质的工艺因素都对充型能力有影响.     

消失模铸造充型过程的研究进展及展望

从充型特性以及传热和传质两个方面回顾了消失模铸造充型过程的研究进展，指出了以往研究中的不足和以后的发展方向。     

油气管道CO2腐蚀过程中弹状流的影响

通过分析弹状流近壁面处的动力边界层和扩散边界层及弹状流对管壁CO2腐蚀的影响,发现弹状流动特性对管壁的质量传递、动量交换、管壁处的电化学腐蚀以及腐蚀产物膜的形成和破坏有显著的影响作用。提出弹状流动形态和CO2腐蚀产物膜特性是管壁腐蚀速率和腐蚀形态的重要影响因素,弹单元内的壁面切应力变化特性、正应力变化特性、壁面传质变化特性以及电化学腐蚀特性的非线性耦合作用是油气管道内壁CO2腐蚀的重要影响因素。在此基础上阐述了CO2腐蚀产物膜的微观结构、力学特性以及膜内的传质特性对腐蚀产物膜的形成、破坏以及修复作用。     

Influence of laser parameters on segregation of Nb during selective laser melting of Inconel 718

A transient three-dimensional powder-scale model was established for understanding the flow field and mass transfer within the molten pool during the selective laser melting (SLM) of Inconel 718 alloy by considering some important physical phenomena, such as, a transition from powder to solid, nonlinearities produced by temperature-dependent materials' properties, and fluid flow in the calculation. The influence of laser power or scanning speed on the flow field and cooling rate was discussed in detail. The simulation results reveal that the motion of molten pool and higher cooling rate promote the mass transfer and benefit the solute distribution by increasing laser power. However, with increasing the scanning speed, the melt flow speed and cooling rate are elevated, resulting in an agglomeration of the solute elements, which is ascribed to the shorter dwelling time of liquid. Therefore, the segregation of Nb can be effectively suppressed by increasing laser power or decreasing scanning speed, which can decrease the dwelling time of liquid.     

Breakaway properties of film formed on copper and copper alloys in erosion–corrosion by mass transfer equation

Erosion–corrosion tests on copper and three types of copper alloys in a 1 wt% solution of CuCl₂ were carried out at various flow velocities using a jet‐in‐slit testing apparatus, which is capable of reproducing various hydrodynamic conditions. A damage profile of a specimen was developed using a surface roughness meter to evaluate locally occurring damage. The damage depth rate for copper, beryllium copper, and a 70/30 copper nickel alloy increased with increasing flow velocity, and suddenly increased at a certain velocity, which is called the breakaway velocity. The breakaway velocities at the central and disturbed part of a specimen were different for each sample, indicating that the hydrodynamic conditions of the flowing solution had an effect. The damage depth rate, calculated from the mass transfer equation, which involved mass transfer in the concentration diffusion layer and in the corrosion product film, could be fitted to the experimental data, suggesting that the mass transfer equation can be applied to the evaluation of erosion–corrosion damage. The corrosion product film was exponentially broken away at velocities higher than the breakaway velocity. The breakaway properties of the corrosion product film were confirmed to be different for each material, since the power of the exponential equation was different for each sample.     

相界面逸出惰性气泡时相间传质

本文针对液-液两相接触时的传质过程,以流体动力学理论及相间传质的渗透理论为基础,根据界面上惰性气泡逸出界面时流体流动及传质过程的特征,导出了气泡促进的相间传质系数的数学关系式。该关系式表明,流体中传质速率不仅与逸出气泡的体积速度的平方根成正比,同时与气泡大小、界面上气泡分布密度等参数有关。该关系式能较好地描述文献中的实验数据。     

Effect of immersion time on the hydrogen content and tensile properties of A350LF2 steel exposed to hydrogen sulphide environments

The effect of immersion time on the hydrogen content and tensile properties of A350LF2 steel exposed to hydrogen sulphide environments was investigated by immersion tests, hydrogen content measurements and tensile tests. The results show that both hydrogen content and relative tensile strength and plasticity loss increased first and then decreased with increasing immersion time. High mass transfer resistance of corrosion films can be responsible for that hydrogen content decreased after 240 h immersion. A probable mechanism is proposed to interpret the reason for hydrogen content result. The tensile property loss and embrittled region were closely associated with hydrogen content.