STUDY ON NON-SINUSOIDAL OSCILLATION FOR SLAB CONTINUOUS CASTING MOLD WITH HIGH CASTING SPEED Ⅰ. Mechanism of Oscillation Marks Formation

通过分析2.0 m/min拉速稳定浇铸时振动周期内弯月面初凝坯壳的受力情况,阐述了高拉速连铸坯表面振痕形成过程,给出振动参数与最大液体摩擦力和最大保护渣渣道动态压力关系;结合振动参数对振动过程参数的影响和实际设备状况,提出了振动参数优化方向,确定了拉速升至2.2 m/min时的振动参数值.结果表明,弯月面初凝坯壳在钢水静压力、摩擦力和保护渣渣道压力作用下随凝固进程形成振痕,振痕生成位置取决于初凝坯壳糊状区固相分率;随拉速提高,应降低振频、增大振幅和非正弦振动因子,以改善振动效果和振痕形貌;拉速升至2.2 m/min时的适宜振频、振幅和非正弦振动因子分别为145 min-1,±5.0 mm和0.25.     

自硬呋喃树脂砂在高铬铸铁生产中的应用

介绍了自硬呋喃树脂在高铬铸铁生产中的实际应用 ,从原材料的选取 ,树脂砂的制备工艺 ,到采用该砂进行造型制芯的操作要点均作了较为详细的阐述。实践证明 ,采用自硬呋喃树脂砂生产高铬铸铁泵类过流件 ,可较好地满足其尺寸精度、表面光洁度要求 ,能有效地克服裂纹等铸造缺陷的产生     

Oxidation protection of NiCoCrAlY coatings on γ-TiAl

The effect of NiCoCrAlY overlay coatings on the oxidation resistance of γ-TiAl was studied at 900 ℃ in static air. To hinder the interdiffusion of the elements, the Al/Al2O3 layer was added between the coating and the alloy. The results show that the TiAl alloy exhibits poor oxidation resistance. NiCoCrAlY coating can not effectively protect the γ-TiAl substrate from high temperature oxidation because of the serious interdiffusion between the coating and the substrates. With Al/Al2O3 diffusion barrier, the NiCoCrAlY coating exhibits excellent oxidation protection on γ-TiAl alloy.     

高强度耐大气腐蚀钢焊条研制

讨论了影响所研制焊条熔敷金属理化性能的主要因素,降低焊缝中的S、P含量及适当控制C、Mn的含量可以获得良好的综合力学性能,适量的Ni、Cr、Cu对提高耐大气腐蚀性十分有效.分析了影响该焊条工艺性能的主要因素,合理的大理石与萤石配比及稳弧剂的加入,有利于提高焊条工艺性能.通过焊条熔敷金属理化性能检测、金相分析、冷裂纹敏感性实验,结果表明,各项指标均达到<铁道车辆用高强度耐大气腐蚀钢焊接材料(焊条、焊丝)订货技术条件>的要求,并在铁道车辆上得到推广应用.     

Effect of grain size on high-temperature oxidation behavior of Cu-80Ni alloy

1　INTRODUCTIONTheoxidationofunalloyedcopperandnickelhasalreadybeenstudiedindetail.Whilethehigh tem peratureoxidationofCu Nialloys ,alsostudiedanumberoftimestodate[13] ,isanexampleofarela tivelysimpleclassofscalingofbinaryalloysbyasin gleoxidant,becausethemetalsformacontinuousse riesofsolidsolutions ,whiletheiroxides ,CuO ,Cu2 OandNiO ,exhibitsmallmutualsolubilitiesandshowsignificantdifferencesinthethermodynamicstabilityandparabolicgrowthrates .Thus ,copper richalloysformexternalscales…     

高速电弧喷涂FeAlCr/Ni包Cr3C2涂层高温性能

用高速电弧喷涂技术制备了FeAlCr/Ni包Cr3C2涂层,并对涂层的耐高温冲蚀性能、高温腐蚀性能和高温磨损性能进行了研究.结果表明,与基体比较涂层具有良好的耐高温冲蚀性能,并随温度的升高和冲击角度增大,耐冲蚀性能提高;良好的高温抗腐蚀性能,随温度升高,腐蚀率略有上升;优异的常温耐磨损性能,超过550℃的耐磨损性能高.     

Thermal expansion of lattice parameter of （powder） silicon up to 1473 K

The XRPD (X-ray powder diffxactometry) patterns of silicon powder with a unit cell structure of diamond were determined from 298 to 1473 K. Lattice parameters of Si linearly increase with temperature. The thermal shifts of the positions of all reflection peaks are linearly correlated with the temperature. The coefficients of the intrinsic linear thermal expansion and volumetric thermal expansion were determined as 3.87×10-6/K and 1.16×10-5/K respectively. It indicates that Si is still a suitable standard in the XRPD method at high temperatures.     

石英玻璃热膨胀性能的高温分子动力学研究

采用基于第一性原理的COMPASS力场对石英玻璃的热膨胀性能作了分子动力学研究。结果分析表明Si-O键长与Si-O-Si键角是导致结构随温度变化的主要因素，两者的变化趋势和变化速率决定了材料热膨胀的不规则性。此外，还根据四面体体积随温度的变化粗略估算了四面体间隙的变化，对负热膨胀现象做了进一步讨论。     

SG变质处理对高锰钢铸态及热处理组织的影响

SG变质处理能有效地抑制铸态组织中柱状晶的生长,细化奥氏体组织并降低其方向性,减少晶间碳化物数量并使之细化;对热处理组织,SG变质处理可以加速碳化物溶解,缩短水韧处理的保温时间或降低水韧处理的温度。SG的这些变质作用对高碳及合金化类型的高锰钢尤为显得有实际意义。     

45CrNiMoV低合金高强钢在氯化物溶液中闭塞区化学状态的研究

采用模拟闭塞电池研究45CrNiMoV低合金高强钢在NaCl溶液中闭塞区内化学状态的变化.