495型柴油机增压后机体的改进设计方法

应用有限元数值计算方法对495柴油机在增压前后机体的应力分布及变形情况进行了研究，根据分析结果对薄弱部位作了改进设计，并进行了改进设计效果评估。结果表明，采用此有限元分析方法可为机体的评估和多方案改进设计提供依据。     

WD618.44柴油机配气凸轮的改进

针对WD618.44性能试验后的拆检过程中,发现活塞顶部有裂痕,且凸轮轴磨损严重,已不能满足正常使用要求的情况,在保证不降低性能的条件下,配合活塞顶部避碰坑加深和动力学计算重新设计了高次方动力凸轮.新凸轮能有效减小飞脱量及降低凸轮接触应力,保证了使用可靠性.并且发动机其它性能指标优于或保持原机水平.     

惯性通道式液力减振器动态特性研究

建立了惯性通道式液力减振器的物理模型，推导出动刚度、滞后角和传递率的数学表达式，研究惯性通道局部截面积对液力减振器动态特性及系统力传递率的影响，仿真结果表明：优化局部截面积，可在较宽的频带内得到较好的隔振效果。     

预测柴油机排气消声器消声量试验方法研究

采用白噪声信号作为标准声源的输入信号，在常温无气流条件下对消声器实物模型进行了静态放声试验。使用消声器倍频程消声量的测量结果，并应用相似准则，推算出消声器在高温条件下各频带的消声量，从而计算出消声器的总消声量。将此方法应用于某一型号船用高速柴油机排气消声器，将通过放声试验推算的结果与实际配机试验的倍频程数据进行对比分析，结果表明该方法用于预测消声器消声量是可行的。     

基于多参数评估柴油机技术状况的模糊方法研究

本文针对不同使用期的柴油机进行了测试，测得了表征柴油机技术状况的特征参数，并利用模糊距离度量的方法对柴油机的技术状况进行评判。试验结果表明，采用多参数进行柴油机技术状况评判的方法可靠有效。     

498柴油机隔振系统设计与试验研究

在内燃机与支架之间加上隔振设备是降低内燃机振动和噪声的有效方法之一。作者介绍了498柴油机隔振系统方案和橡胶隔振器的设计，并讨论了引起498柴油机机体振动的主要原因。试验表明，所设计隔振系统能有效的降低内燃机传递给支架的振动。     

东风4 7215内燃机车凸轮轴失效分析

通过对失效凸轮轴的外观、化学成分、金相组织和力学性能等综合分析研究，认为在凸轮轴热处理工艺上存在缺陷，淬火层过薄或未淬火、接触应力过大是导致凸轮轴出现麻点、剥离的主要原因，提出了预防凸轮轴失效的措施及改进建议。     

Enhancement of wear resistance of ductile iron surface alloyed by stellite 6

This paper deals with the improvement of the wear resistance of ductile iron surface alloyed by a hypoeutectic stellite 6 alloy. In this regard, the surface alloyed layer with 3 mm thickness deposited on ductile iron using tungsten inert gas (TIG) surface processing. The microstructure, hardness and wear resistance of surface alloyed layer were investigated using optical microscopy, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis, Vickers hardness (HV0.3) and pin-on-plate tests. The results showed that the microstructure of the surface alloyed layer consisted of carbides dispersed in a Co-based solid solution matrix with dendritic structure. This microstructure was responsible for the improvement of the hardness and wear resistance of the coating. Further investigations showed that the dominant mechanism of the wear in the coated and uncoated samples was delamination wear.     

Hot corrosion behavior of powder metallurgy Rene95 nickel-based superalloy in molten NaCl–Na2SO4 salts

Hot corrosion behavior of powder metallurgy (PM) Rene95 Ni-based superalloy in molten 25%NaCl + 75%Na₂SO₄ salts at 650 °C, 700 °C and 750 °C are investigated by weight loss measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Experimental results show that hot corrosion kinetics follow a square power law at 650 °C and linear power laws at 700 °C and 750 °C. The corrosion layers on the surface of PM Rene95 superalloy are detected to be mainly composed of Cr₂O₃, NiO, and Ni₃S₂ at each temperature. Besides, small amounts of NiCr₂O₄ at 700 °C and NaCl at 750 °C are observed respectively. Cross-sectional morphologies and corresponding elemental maps indicate that corrosion layers near scale/alloy interface are composed of oxides at 650 °C while duplex oxides and sulfides at 700 °C and 750 °C. According to these results, a cooperating mechanism of oxidation and sulfuration for hot corrosion of PM Rene95 Ni-based superalloy is confirmed.     

Synthesis and characterization of titanium-45S5 Bioglass nanocomposites

Titanium-45S5 Bioglass nanocomposites were synthesized by the combination of mechanical alloying and powder metallurgy process. The structure, mechanical and corrosion properties of these materials were investigated. Microhardness test showed that the obtained material exhibits Vicker’s microhardness as high as 770 HV_0.2 for Ti-20 wt.% 45S5 Bioglass, which is more than three times higher than that of a conventional microcrystalline titanium (225 HV_0.2). Additionally, titanium-10 wt.% of 45S5 Bioglass nanocomposites (i_c = 1.20 × 10⁻⁷ A/cm², E_c = −0.42 V vs. SCE) were more corrosion resistant than microcrystalline titanium (i_c = 2.27 × 10⁻⁶ A/cm², E_c = −0.36 V vs. SCE). In vitro biocompatibility of these materials was evaluated and compared with a conventional microcrystalline titanium, where normal human osteoblast (NHOst) cells from Cambrex (CC-2538) were cultured on the disks of the materials and cell growth was examined. The morphology of the cell cultures obtained on Ti-10 wt.% 45S5 Bioglass nanocomposite was similar to those obtained on the microcrystalline titanium. Mechanical alloying and powder metallurgy process for the fabrication of titanium-45S5 Bioglass nanocomposites with a unique microstructure, higher hardness, lower Young’s modulus and better corrosion resistance, in comparison to microcrystalline titanium, were developed. On the other hand, Ti-10 wt.% 45S5 Bioglass composites posses higher fracture toughness compared to 45S5 Bioglass. The proper modification of chemical composition and microstructure of Ti-bioceramic nanocomposites can expand the use of titanium in the biomedical fields.