硅铝复合材料杨氏模量有限元计算研究

为预测硅铝复合材料的杨氏模量,建立了与其真实显微组织结构相一致的有限元模型.结合应力应变方程,计算了硅含量为40％(质量分数)的40Si-Al复合材料的表观杨氏模量.采用共振法测试了40Si-Al的真实杨氏模量.比较有限元计算结果与实验结果,分析了材料因素和界面因素对硅铝复合材料杨氏模量的影响.结果表明:材料因素对40Si-Al复合材料杨氏模量的降低起了主导作用.     

表面镀钨金刚石/铜复合材料的有限元模拟

利用有限元分析软件ANSYS,对表面镀钨金刚石/铜复合材料进行了数值模拟,研究了金刚石体积分数、金刚石粒径及镀层厚度对表面镀钨金刚石/铜复合材料导热系数和热膨胀系数的影响。结果表明:随着金刚石体积分数的增加、金刚石粒径的增大、镀层厚度的减小,复合材料的导热系数呈现出增加的趋势,与文献数据的变化趋势相符,热膨胀系数受金刚石体积分数影响最大,金刚石粒径选在150~200 μm较为合适。     

高热导率低热膨胀系数Cu-ZrW_2O_8复合材料的制备与性能

以负热膨胀材料ZrW2O8与金属Cu为原料,分别采用常规烧结法和热压法制备具有高热导率低膨胀系数的新型Cu基复合材料Cu-ZrW2O8,研究ZrW2O8体积分数与烧结方法对该复合材料致密度、热导率及热膨胀系数的影响.结果表明:热压法制备的Cu-50%ZrW2O8复合材料的热导率达173.3 W/(m·K),致密度为91.6%,均明显高于常规烧结样品;热压样品的热膨胀系数为11.2×10-6K-1,稍高于常规烧结样品:在150～300℃温度范围内热处理后该样品的平均热膨胀系数降低到10.87×10 -6K-1,较纯Cu的平均热膨胀系数17×10-6K-1低很多,有望成为一种新型的电子封装材料.     

喷射沉积Si-Al合金的数值模拟结果与分析

采用热辐射修正,模拟了喷射沉积Si-Al合金的凝固过程,研究了熔滴的速度、热交换作用系数、温度、熔滴冷却速度及固相分数与沉积距离的关系,讨论了辐射相修正前后熔滴的温度和固相分数的变化以及雾化压力和沉积距离对固相分数的影响.     

轻质Si-Al电子封装材料制备工艺的研究

探讨采用传统粉末冶金方法制备轻质、高性能Si-50％Al(质量分数，下同)电子封装材料的可能性。研究了粉末粒度组成、压制压力、烧结温度对材料室温导热性和室温到200℃间热膨胀系数的影响。发现采用一定的粉末粒度组成，高压制压力、高温和适当的时间烧结能够获得综合性能较好的Si-Al复合材料。     

铜基电子封装复合材料的回顾与展望

介绍了国内外铜基电子封装复合材料的性能、研究、生产现状以及存在的问题，同时展望了铜基电子封装材料的发展趋势。     

基于有限元方法的回转窑热平衡计算

根据某炭素厂的回转窑参数进行建模。考虑到模型的复杂性,对模型进行拆分,分别建立二次风系统和窑体的计算模型;以二次风系统的计算结果作为窑体的计算边界条件,对窑体进行基于有限元方法的热平衡计算,对计算结果进行分析,并提出工艺控制的优化意见。     

GCr15钢的热膨胀系数

 采用Netzsch DIL 402C 热膨胀分析仪研究了GCr15钢在200~1000℃温度范围内的热膨胀规律,通过取样、制样、试验测量得到试验数据,采用微分法进行数据运算与处理,得到瞬时热膨胀系数并发现一定规律。研究结果表明,GCr15钢的瞬时热膨胀系数在1.5×10-5~8.0×10-5之间,且在奥氏体?涞阄露惹昂蠓直鹩胛露瘸嗜畏焦叵担螱rüuneisen关系式和Debye模型的规律。     

W/Ti层状复合材料的弯曲断裂行为及其有限元模拟

层状增韧复合材料是提高钨材料韧性的有效方法之一.利用放电等离子体烧结装置在不同温度下连接制备了W/Ti层状复合材料,分析了该复合材料的组织、三点弯曲力学性能和断裂机制,并对其三点弯曲断裂过程进行了有限元模拟.结果表明,Ti韧化层可以有效提高钨材料的韧性,W/Ti层状复合材料的三点弯曲曲线上显示了明显的"伪塑性".W/T...     

Peculiarities of the thermal expansion of composite antifriction-type fluoroplastic materials

Temperature and concentration dependences of the thermal coefficient of linear expansion are studied in composite fluoroplastic materials used for antifriction purposes. It is shown that these characteristics have a number of peculiarities that do not obey the general rules typical for filled fluoroplastics.Translated from Poroshkovaya Metallurgiya, No. 11(359), pp. 94–97, November, 1992.     

热带钢轧机轧辊热变形的快速有限元模型

分析了解析法与简化方法的缺点,采用有限元法建立轧辊热变形计算模型.针对轧制过程中轧辊热变形计算数据特点,将计算任务分为负责静态数据准备的预计算和负责动态数据准备与热变形求解的更新计算,换辊时进行预计算,计算任意时刻的热变形时只需进行更新计算,计算量远小于标准有限元程序.根据特殊处理的计算流程,编写了基于轴对称有限元法的轧辊热变形程序,其计算结果与ANSYS结果一致,精度均高于简化方法约30%.自编轧辊热膨胀有限元程序计算精度高,耗时少,满足在线热膨胀预报要求.     

Thermal expansion of two-phase texturized composite materials

Conclusions Theoretical and experimental studies were made of the effects of temperature and composition on the thermal expansion of deformed (texturized) Mo-Cu two-phase composite materials, whose component phases differ markedly in their properties. The anisotropy of thermal expansion of such composite materials was investigated, and it was established that their volume expansion shows very little variation with deformation. It is demonstrated that two-phase composite materials can be formulated exhibiting thermal expansion characteristics controlled by their composition and the type and degree of plastic deformation.Translated from Poroshkovaya Metallurgiya, No. 3 (111), pp. 82–89, March, 1972.     

The effects of molybdenum and aluminum on the thermal expansion coefficients of nickel-base alloys

The effects of molybdenum and aluminum on the mean linear thermal expansion coefficients from room temperature to 1050°C were determined for two types of nickel-base alloys. The Solid Solution Alloys were cast and homogenized Ni-Co-Cr-Mo alloys with 0, 312, and 612 nominal wt pct molybdenum concentrations. The Gamma Prime Alloys were wrought and heat-treated Ni-Cr-Mo-Al(Ti) alloys with 0, 2, 5, and 8 nominal wt pct molybdenum in each of four aluminum plus titanium levels (3 pct Al, 412 pct Al, 6 pct Al, or 1 pct Al + 312 pct Ti nominal wt pct). Thermal expansion coefficients were determined on at least two specimens from each alloy. It was found that molybdenum lowers the thermal expansion coefficients of both the cast Ni-Co-Cr solid solutions and the wrought Ni-Cr-Al(Ti) two-phase alloys. Both aluminum and titanium were also observed to decrease expansion coefficients in the two-phase, γ + γ, alloys. Results are discussed in terms of relative melting point effects between solute and solvent elements, and in terms of the volume fraction of the γ phase present.     

The effects of molybdenum and aluminum on the thermal expansion coefficients of nickel-base alloys

The effects of molybdenum and aluminum on the mean linear thermal expansion coefficients from room temperature to 1050°C were determined for two types of nickel-base alloys. The Solid Solution Alloys were cast and homogenized Ni-Co-Cr-Mo alloys with 0, 312, and 612 nominal wt pct molybdenum concentrations. The Gamma Prime Alloys were wrought and heat-treated Ni-Cr-Mo-Al(Ti) alloys with 0, 2, 5, and 8 nominal wt pct molybdenum in each of four aluminum plus titanium levels (3 pct Al, 412 pct Al, 6 pct Al, or 1 pct Al + 312 pct Ti nominal wt pct). Thermal expansion coefficients were determined on at least two specimens from each alloy. It was found that molybdenum lowers the thermal expansion coefficients of both the cast Ni-Co-Cr solid solutions and the wrought Ni-Cr-Al(Ti) two-phase alloys. Both aluminum and titanium were also observed to decrease expansion coefficients in the two-phase, γ + γ, alloys. Results are discussed in terms of relative melting point effects between solute and solvent elements, and in terms of the volume fraction of the γ phase present.     

界面对复合保温材料热学性能劣化作用机理

为了考察界面对复合保温材料热学性能的影响,成型了一组EPS含量不同的复合保温砂浆试件,并研究了这些试件在经历干湿循环和冻融循环作用后的导热系数.通过确定有机保温组分和基体的影响因子值,间接求得界面对复合保温材料热学性能的影响值.实验结果表明,当有机组分EPS的体积分数超过50%时,复合保温砂浆试件的热学性能明显劣化.结合理论分析认为,界面是影响有机-无机复合保温材料热学性能变化的重要原因.特别是当有机保温组分在复合材料中的体积分数超过一定值时,界面成为导致材料热学性能劣化的关键因素.因此,在复合保温材料开发和应用中,必须对有机保温组分的掺量加以限制.     

Finite element analysis of thermal stresses in functionally graded cemented carbides

Abstract

In this study, finite element method and X-ray diffraction measurement were used to determine the thermal stress distribution of functionally graded WC–Co composites. The calculated results show that high stress concentration occurs in the cobalt gradient zone, tensile stress pile-up occurs in the cobalt rich zone and compressive stress pile-up occurs in the surface zone. As the sintering time is increased, compressive residual stress in the surface zone has a tendency of decreasing. The maximum value of compressive stress in the surface zone is 250 MPa. The results are in good agreement with X-ray diffraction measurement results. For the purpose of this work, the material design method is achieved by changing the calculated parameters.     

Effective thermal conductivity of polycapillary composite materials. II. The influence of convective heat exchange in the channels on the effective thermal conductivity of polycapillary composite materials

Translated from Poroshkovaya Metallurgiya, No. 5(353), pp. 80–84, May, 1992.     

Volumetric thermal expansion coefficients of the equiatomic Na–K and K–Rb melts

The volumetric thermal expansion coefficients of the equiatomic Na–K and K–Rb melts at 373 K are calculated using variational method with an additive hard-sphere reference system. It is found that the Krasko–Gurskii model pseudopotential with the exchange-correlation Geldart–Vosko function yields better agreement with the experimental data as compared to the local Animalu–Heine pseudopotential with the exchange-correlation Toigo–Woodruff function.