60Si2MnA波形弹簧制造及真空热处理工艺

波形弹簧是安装在高压柱塞主轴上的一个较为重要的零件，它与主轴端面密封结构相连，上端是V形密封圈和V形密封环，下端是石墨环和钢套，在主轴运转时处于受压状态。零件尺寸如图1所示。     

60Si2Mn弹簧扁钢崩料断裂原因分析

60Si2Mn弹簧扁钢在下料过程中发生崩断现象,采用化学成分分析、显微组织分析、力学性能试验等方法对弹簧扁钢的断裂原因进行了分析。结果表明:弹簧扁钢崩料断裂性质为解理断裂;材料原始组织中存在超标的非金属夹杂物是导致弹簧扁钢发生崩断的主要原因,钢中的非金属夹杂物在外力作用下形成裂纹源,随后在下料过程中受力导致裂纹扩展而发生了崩料断裂。     

硅对原位反应自生Mg_2Si/ZM5复合材料热处理态的组织和性能的影响

在真空感应炉中氩气保护下制备材料,用OM,SEM,EDAX及拉伸试验,探讨硅对原位反应自生Mg2Si /ZM5复合材料T6热处理后显微组织和性能的影响规律。结果表明,反应添加物Si在ZM5合金中形成了高熔点、高硬度的Mg2Si强化相,时效处理可促进(Mg17Al12)相沿晶内连续析出,明显地提高了材料的室温与高温强度,如含1.5%Si的复合材料经T6处理后室温屈服强度提高幅度为28.7%,高温抗拉强度与屈服强度提高幅度分别为9.3%、14.0%;此外Mg2Si相的形貌随着硅含量的不同而变化,如含Si 0.5%为时,主要形成细小短棒状或片状共晶Mg2Si相,Si>1%时,则出现了粗大块状或汉字状初生Mg2Si相和片状或短棒状的共晶Mg2Si相;Mg2Si相是一种脆性相,使得该材料呈现出解理断裂,降低了材料的塑性。     

35Si2CrVB钢簧板的高温形变热处理工艺

对35Si2CrVB钢的高温形变热处理工艺进行了研究,确定形变热处理工艺为：950℃奥氏体化后,立即进行高温轧制,形变量ε=27.2%,迅速水淬,在250-420℃范围回火,均能获得良好的强韧性配合,其强化机理是位错强化、结晶强化、析出强化和相变强化的综合作用。     

往复挤压Mg-4Al-2Si合金时Mg_2Si颗粒的破碎规律

采用往复挤压工艺细化Mg-4Al-2Si(AS42)镁合金组织,研究了挤压过程中Mg_2Si颗粒的细化效果、破碎特征、分布规律及破碎机制。结果表明:从铸态到挤压8道次态,随挤压道次的增加,颗粒不断细化,均匀度和弥散度逐渐提高;挤压11道次时,颗粒发生粗化;合金在400℃、应变速率0.01s~(-1)条件下的压缩峰值应力约为75MPa,大于Mg_2Si颗粒的断裂应力(48MPa),挤压使颗粒发生开裂;随挤压道次的增加,位错密度逐渐增大,位错在Mg_2Si颗粒处的数量增多,应力集中急剧增大,从而导致颗粒发生破碎。     

淬火分配工艺对60Si2Mn弹簧钢显微组织和力学性能的影响

对60Si2Mn弹簧钢进行了不同淬火温度(140,160,180℃)的淬火分配(Q&P)处理,研究Q&P处理后该钢的显微组织和力学性能,并与传统淬火+回火(Q&T)工艺处理后的进行对比.结果表明:经Q&P处理后,60Si2Mn弹簧钢的显微组织均为残余奥氏体和马氏体,残余奥氏体的体积分数均大于12％,而经Q&T处理后的显...     

推进生产过程运行质量持续改进的有效措施

本文通过分析和实例指出,在完善了SPC过程能力评估的基础上,如何进行有针对性的质量改进,以有效地提高生产过程的运行质量。文章阐述了这样一个观点：贯彻SPC时所采集样本的实际分布情况和样本的单值进程图。在实施过程实时监控中有着极为重要的作用。     

60Si2Mn圆钢断裂失效分析

采用化学分析、断口扫描和金相检验方法,对60Si2Mn圆钢在试用过程中出现的频繁疲劳、断裂进行了分析。60Si2Mn圆钢脆断的原因是由于热处理不当,使淬火组织过烧,造成弹簧圆钢综合性能差而引起的。     

Microstructure and Mechanical Behavior of in Situ Primary Si/Mg_2Si Locally Reinforced Aluminum Matrix Composites Piston by Centrifugal Casting

Al-Si pistons are frequently damaged by burning piston top surface due to elevated combustion temperature, and by rubbing the first ring groove against the engine cylinder liner. To prevent piston from these damages, some technologies were invented, such as mounting high Ni cast iron ring around the first ring groove in Al alloy piston body and thermal resistant steel on piston top surface, and fabricating Al composite pistons by squeeze casting for enhancing the whole or local piston performance. In this paper, composite pistons locally reinforced with in situ primary Si and primary Mg2Si particles are fabricated by centrifugal casting. The microstructure characteristics, hardness and wear resistance of the composite piston are investigated and the motion characteristic of the in situ particles in centrifugal field is analyzed. The results of the experiments show that primary Si and Mg2Si particles mix up with each other in melt and segregate at the regions of piston top and piston ring grooves under the effect of centrifugal force. Particulate reinforced regions have a higher hardness and better wear resistance compared with the unreinforced regions and this performance increases after heat treatment. The analysis result of particle movement shows that, primary Si and primary Mg2Si particles move at approximately the same velocity in the centrifugal field, because of the growth of primary Si and fusion after colliding between primary Si particles, which compromised the velocity difference of primary Si and primary Mg2Si particles caused by the difference of their densities. Research results have some theory significance and applicative value of project in development of new aluminum matrix composites piston products.     

纳米硅-氧化硅薄膜的XPS测量

利用XPS能很好地分辨出硅基纳米硅-氧化硅膜层中的n-Si和n-SiO2。对Si2P峰进行的拟合处理，可计算出n-Si和n-SiO2的含量，其结果与RF-磁控溅射沉积薄膜中所用的复合靶Si和SiO2的面积比基本一致。     

Scanning tunnelling microscopy studies of heteroepitaxy: CaF2 on Si(111)

We apply scanning tunnelling microscopy and tunnelling spectroscopy to study the initial stages of CaF₂ epitaxy on Si(111)-(7×7) for a range of deposition temperatures. We find that deposition at surface temperatures <700°C leads to CaF₂ clustering. At temperatures between 750 and 800°C two new structures, a 2×3 and a (√3 X √3***)R30°, are observed. Tunnelling spectra and topographs obtained at different energies allow us to measure interface band gaps, and determine the valence state of Ca bonded directly to silicon and the valence state of Ca in the second layer. More importantly, we demonstrate that STM can be used to image thick insulating layers of CaF₂ by tunnelling into the conduction band of the films. One of our goals in this study has been to test the ability of STM to image insulating multilayers. It is generally believed that STM cannot be applied to insulators. We find, however, that despite the large band gap of ～12 eV, the CaF₂ conduction band is accessible, and that insulating films can be imaged by STM.     

Mg2Si和MgCu2相电子结构、弹性性能第一性原理研究

本文通过第一性原理计算研究了MgCu2和Mg2Si相的结构稳定性、电子结构和弹性性能等.计算的结构参数与实验理论结果非常吻合.合金形成热和结合能计算结果表明,MgCu2具有较强的结构稳定性,Mg2Si具有较强的合金化能力.计算的剪切模量G、体模量B和杨氏模量E显示:MgCu2属于延性材料,Mg2Si属于脆性材料,Mg2Si的刚度较大.态密度(DOS)和Mulliken布居数的计算表明,Mg2Si离子键较强.