A study on the manufacturing conditions of metal matrix composites by low pressure infiltration process

Metal fiber preform reinforced aluminum alloy composite as made by the infiltration of molten metal under low pressure casting process. The infiltration behavior of filling pattern and the velocity profile with low-pressure casting process was investigated. The thermocouple was inserted into the preform in order to observe the infiltration behavior. The infiltration of applied pressure time, 1, 2 and 5 s under constant pressure of 0.4 MPa was completely filled during 0.4 s. In these conditions, molten aluminum alloy has successfully infiltrated to FeCrSi metal fiber preform by low-pressure casting process. It was observed the porosity of composites for reliability of composites. The automobile piston was developed with FeCrSi reinforced aluminum alloy that is 0% porosity by the optimal applied pressure and applied pressure time.     

Automotive tribology overview of current advances and challenges for the future

This keynote address will provide a comprehensive overview of various lubrication aspects of a typical powertrain system including the engine, transmission, driveline, and other components, as well as the integration of these lubrication and surface engineering concepts into a unified automotive powertrain system. In addition, this presentation will focus on the current status and future trends in automotive lubricants including discussion of current and anticipated future requirements of automotive engine oils. This presentation will also review the current standard ASTM (American Society for Testing and Materials) test methods for engine lubricants and other compilations of automotive standards. In addition to engine oil test development, industrial researchers are developing light-weight materials such as non-ferrous materials (Al, Mg) for engine and drivetrain materials to replace the current heavy-weight cast iron blocks. Recent industrial developments include high strength and high density of composite materials, high volume liquid molding and hydroforming technology, structural adhesive boding, and the ability to mold large structural components. Industrial researchers have also developed processing improvements for forming more complex stamped aluminum parts or panels, more robust stamping, and improved casting techniques. In this paper, our insights and perspectives on future trends in light-weight tribological material and nonotribology will also be reviewed.     

某高功率柴油机活塞失效分析及解决方案

针对某高功率柴油发动机铸造铝合金活塞在冷热冲击台架试验后出现顶部开裂现象,综合了活塞及对手件尺寸检测、涡流探伤检测、金相检测及电镜检测的结果,经分析判定为铸造工艺中铝合金氧化皮夹杂是此次活塞出现开裂失效的根本原因。根据分析结果,针对活塞开裂情况提出了对手件设计方案及活塞铸造工艺优化方案并对优化后的活塞进行了三轮冷热冲击台架试验+800小时耐久台架试验,均未再出现活塞开裂现象,可判断为改良方案有效。     

大型薄壁复杂铝件铸造技术的现状与发展

随着航天、国防、汽车等工业的不断发展，对铸件的要求向小余量、薄壁、高精度、高性能方向发展：介绍了大型薄壁铸件的特征，叙述铝合金复杂薄壁铸件的发展特点，提出复杂薄壁铸件对先进的精密成形技术及铸造工艺的要求.     

基于CAE技术的汽车铝板发动机盖刚度研究

随着汽车产业的发展,轻量化在汽车制造领域占据越来越重要的地位。相较于钢板来说,铝板的塑性低、易回弹,在汽车扣合件的外板中经常存在刚度不足的问题。以铝板发动机盖外板为研究对象,采用有限元法对成形过程中的各工艺参数进行优化,再通过实验验证,较好解决了铝板成形过程刚度不足的问题。     

铝合金冷硬树脂砂在大功率柴油机铸件中的应用研究

柴油机是以柴油或劣质燃料油为燃料,压缩发火的往复式内燃机,在船用发动机中,柴油机已经取得了绝对统治地位,因此柴油机铸件质量的好坏决定了柴油机的使用寿命长短,应用铸造铝合金冷硬树脂砂铸造工艺,能较大幅度地提高柴油机铸件的质量,从而提高柴油机的使用寿命。     

汽车发动机缸体铸造技术分析

随着当今社会经济与科学技术的协同发展,汽车制造行业的发展也十分迅速。而在汽车制造中,发动机缸体是一个关键部分。为实现发动机制造及其应用质量的良好保障,本文特对其发动机缸体的铸造技术进行分析。希望通过本次的分析,可以为汽车发动机缸体加工及其后续应用效果的保障提供科学参考,以此来促进汽车生产制造质量的进一步提升。     

大型铝合金活塞倾转铸造机轻量化设计与研制

介绍了一种大型铝合金活塞倾转铸造机的设计,与传统设计方法相比,倾转工作台的尺寸可减小54％,重量可降低43％,实现了直径在200 mm以上大型铝合金活塞铸造机的轻量化设计,达到节能降耗的目的。     

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.     

活塞内冷油腔的振荡传热特性及位置的研究

以一款非道路用高压共轨柴油机铝合金活塞为研究对象，在试验测试的基础上建立了活塞-内冷油腔耦合传热数值仿真模型，研究了发动机循环过程中内冷油腔的振荡传热特性，分析了内冷油腔位置对活塞温度场和热应力场的影响规律。研究结果表明：在发动机循环过程中，内冷油腔壁面换热系数随油腔中机油分布规律周期性变化；内冷油腔靠近活塞顶面和环槽底面时，能显著降低活塞最高温度及一环槽温度，内冷油腔设计时应在结构强度允许范围内，尽量靠近活塞顶面和环槽底面；内冷油腔过于靠近活塞壁面时，活塞第三环槽及内腔顶面区域出现较大的局部热应力。