Mg、Si对Al熔体中氢含量及氩气除气效果的影响

研究了合金元素Mg、Si对Al熔体中的氢含量及氩气除气效果的影响。结果表明，Mg、Si元素均明显增强了Al熔体的吸气倾向。在Mg元素单独存在时，熔体中的氢含量随Mg含量的增加而上升，氩气除气效果也逐渐明显，但除气后，熔体中的氢含量仍较高；Si的加入能阻碍Al熔体中的氢原子向氩气气泡的扩散，因而，明显降低了氩气除气的效果；Mg、Si元素共存不仅增加了铝合金熔体的吸氢倾向，而且增加了除气的难度，但短时间除气仍有一定效果。     

离子束增强沉积Si─N膜

用离子束增强沉积方法制备了ＳｉＮ薄膜，其中Ｓｉ由一束Ａｒ离子从Ｓｉ靶上溅射下来，在溅射沉积的同时，以一束Ｎ离子轰击正在沉积的膜层，于是获得了ＳｉＮ膜。采用卢瑟福背散射、红外光谱和透射电镜对膜层的成分和结构进行了分析，结果表明：膜面平整，膜层为非晶或微晶结构，由Ｓｉ和βＳｉ３Ｎ４组成     

半固态60Si2Mn弹簧钢浆料直接轧制研究

研究了60Si2Mn弹簧钢半固态浆料的直接轧制.结果表明在试验条件下,当搅拌时间为2 min时,可以获得尺寸大小为100～300 μm、固相率为50%～60%的球状初生奥氏体的半固态浆料,这样的半固态浆料便于从搅拌室底孔中放出;60Si2Mn弹簧钢半固态浆料可以实现顺利轧制,但球状初生固相颗粒与液相发生了分离,球状初生固相颗粒集中在轧材的心部,而液相偏聚在轧材的四周.     

曲轴连杆低速大扭矩液压马达低速特性的仿真研究

本文建立了曲轴连杆低速大扭矩液压马达进口节流系统的数学模型。推导了低速域马达输出轴角速度随时间变化的理论解析式,采用计算机仿真手段,研究了马达自身因素及系统因素对低速稳定性的影响,通过动态仿真验证了理论分析的正确性。     

Microstructure of reactive sintered Al bonded Si3N4-SiC ceramics

Aluminium nitride-silicon nitride-silicon carbide （AIN-Si3N4-SiC） composite ceramics were prepared to increase the bending strength and improve the phase structure of Si3N4-based ceramics. The ceramics were made by reactive sintering in N2 atmosphere at 1 360 ℃, using Al as sintering additive. The phase composing of ceramics was identified with an X-ray diffractometer and the microstructure of the materials was studied by scanning electron microscopy. The results indicate that the phase structure is affected remarkably and the interface modality is changed. The interface between Si3N4 and SiC becomes blurry and that between SiC and AlN matches more better at the same time. But the liquid-phase appears during the reactive sintering along with the addition of AI by which the melting point of Si is decreased. The appearance of liquid Si decreases the bending strength of the ceramics. Lower temperature nitrification technic was introduced to avoid the appearance of liquid-phase Si. The optimum addition of Al was investigated by XRD and SEM analysis in order to obtain the maximal bending strength of materials.     

Thermomechanical treatment of super high strength Cu-8.0Ni-1.8Si alloy

The microstructures and properties of Cu-8.0Ni-1.8Si alloy subjected to different heat treatments were examined by mechanical and electrical properties measurements, optical and transmission electron microscopes observation. The results show that the precipitation process during aging can be accelerated by the cold deforming before aging. As the Cu-8.0Ni-1.8Si alloy is subjected to solution treatment at 970 ℃ for 4 h, cold rolling to 60% reduction, and then aging at 450 ℃ for 60 min, its properties are σb=1 050 MPa, σ0.2=786 MPa, δ=3.2% and conductivity 27.9%（IACS）. The strengthening mechanisms of the alloy include spinodal decomposition strengthening, ordering strengthening and precipitation strengthening. The precipitation of the alloy is nano-scale Ni2Si phase.     

Intermetallic phase formation in directionally solidified Al−Si−Fe alloy

The present study has been undertaken to better understand the solidification behavior of Al−Si−Fe alloys containing 7wt.% Si and 0.9wt.% Fe, with particular regard to the formation of phase during controlled solidification and influence of growth rates on intermetallic phase selection. The alloys studied were Al-7Si-0.9Fe alloys, which were produced by a modified Bridgman solidification arrangement. These alloys were solidified unidirectionally with different growth rates (1–30mm/min). The solidified microstructure of these alloys consists of the growth of primary aluminum and multiple second phase reactions.     

40CrNi2Si2MoVA钢制零件磁痕显示分析

本文采用磁粉、X射线、CT和超声等无损检测和金相分析等方法对40CrNi2Si2MoVA钢制零件的磁痕显示进行了系统分析.研究认为,40CrNi2Si2MoVA钢制零件的磁痕显示为显微成分沿变形方向偏析导致的马氏体转变点Ms差异所致.显微成分偏析是钢锭结晶过程中不可避免的,但可通过优化熔炼工艺参数降低显微偏析的程度.本文还分析了四种磁痕显示的类型及其判别方法.     

用天然石英粉制备氮氧化硅粉末

以天然石英粉为原料，先进行活化预处理，然后在１３５０℃左右进行碳热还原氮化，制备了氮氧化硅粉末。实验结果表明：氮化过程中ＳｉＯ２的转化率及产物中氮氧化硅（Ｓｉ２Ｎ２Ｏ）的含量与ＳｉＯ２的活化程度、氮化温度及添加剂等因素有关，其中氮化温度以１３５０℃为佳；随着ＳｉＯ２活化程度的提高，其转化率也提高；添加少量的ＳｒＯ，可以进一步提高ＳｉＯ２的转化率。此外，还分析了ＳｉＯＣＮ系统中气体分压对Ｓｉ２Ｎ２Ｏ形成的影响。