发动机润滑油液质量在线监测传感器研究

开发一种发动机润滑油质量在线监测传感器。该传感器利用多波长光来感知润滑油质量变化情况,对润滑油具有较好的区分能力。实验研究光源强度变化、温度变化对该传感器检测精度的影响,并考察其检测稳定性和对不同等级润滑油的区分能力。结果表明,传感器在实验室条件下能够有效地检测润滑油的质量,且受光源强度变化和环境温度变化的影响较小,具有良好的工作稳定性。

可倾瓦滑动轴承的静态性能分析

研究可倾瓦滑动轴承的静态性能。采用有限差分法求解可倾瓦滑动轴承的雷诺方程,编写三瓦可倾瓦滑动轴承油膜压力分布的计算程序,使用Matlab软件对雷诺方程进行迭代运算,得到轴承的油膜承载力和油膜厚度的分布。结果表明:三瓦可倾瓦滑动轴承轴瓦上同一周向角度的油膜厚度在轴向上是相等的,最小油膜厚度与最大油膜压力均出现在下轴瓦上;在其他条件不变的情况下,偏心率越大时,油膜承载力越大,阻尼系数、温升和功耗越低,而温升和功耗随轴颈转速的增加而呈近似线性规律增加,因此在设计与选用轴承时,为满足轴承承载力的需求,应尽量选择低的轴颈转速和高的偏心率。

镁合金零件压铸过程裂纹成因及数值模拟(英文)

薄壁镁合金件裂纹缺陷制约着其应用,其成因受多方面因素影响。通过虚拟仿真技术,考察了某薄壁镁合金件压铸充型凝固过程的温度场,凝固过程中产生的热应力,及其对裂纹成因的影响。通过数值分析得出AZ91D铸件裂纹的产生与铸件孔洞类缺陷及凝固收缩不一致产生的应力有关,分析结果与实验一致。以数值分析结果为依据,提出了改进方案。

基础油的性能检测及其在工业润滑油液中的应用技术

介绍浓硫酸显色法、加热法、烘干法、放置法、理化测试法、仪器分析法等6种基础油不同性能的常规测试法,并对基础油的应用技术进行讨论;指出在润滑油调配时尽量选用黏度中心值或范围接近的基础油,优先选用性能贡献率较大的基础油,新基础油和新型添加剂的合理配伍将是今后润滑油液调配的关键技术。

压电柔性梁裂缝损伤识别实验

针对压电柔性悬臂梁裂缝损伤检测与损伤程度识别问题,采用小波包分析和小波神经网络相结合的方法进行裂缝深度识别实验研究。利用小波包频带能量谱构造柔性悬臂梁裂缝损伤指标,即能量比相对变化量的H2范数,并建立压电柔性梁裂缝损伤实验装置。激励柔性梁的振动,记录两路压电传感器采集的振动信号,进行小波包分解并计算损伤指标。将这些损伤指标进行组合,作为小波神经网络的输入特征参数,进行裂缝深度即损伤程度的识别。实验结果表明:能量比相对变化量的H2范数对柔性梁的裂缝损伤敏感,对测试噪声不敏感;采用的小波神经网络可以精确识别柔性梁的裂缝深度。

石油钻井钢管车螺纹加工微乳液的研制与应用

根据石油钻井钢管车螺纹的加工要求,筛选出车螺纹加工微乳液所需的基础油、乳化剂、油性剂、极压剂、防锈剂等添加剂,通过正交试验进行配方优化,采用四球机法和攻丝扭矩法进行润滑性能测试,并进行实际应用研究。结果表明,研制的车螺纹加工微乳液具有优异的极压润滑性、防锈性、冷却性和清洗性。该产品各项指标与进口同类产品相当,能满足不同钢级的加工要求,在提高钻井钢管表面质量、延长刀具使用寿命及降低废品率方面效果明显,已成功替代进口同类高端产品。

Effect of Si and Ti on dynamic recrystallization of high-performance Cu-15Ni-8Sn alloy during hot deformation

Effect of Si and Ti on dynamic recrystallization(DRX)of Cu-15Ni-8 Sn alloy was studied using hot compression tests over deformation temperature range of 750-950℃and strain rate range of 0.001-10 s^-1.The results show that the dynamic recrystallization behavior during hot deformation is significantly affected by the trace elements of Si and Ti.The addition of Si and Ti promotes the formation of Ni16Si7Ti6 particles during hot deformation,which promotes the nucleation of dynamic recrystallization by accelerating the transition from low-angle boundaries(LABs)to high-angle boundaries(HABs).Ni16Si7Ti6 particles further inhibit the growth of recrystallized grains through the pinning effect.Based on the dynamic recrystallization behavior,a processing map of the alloy is built up to obtain the optimal processing parameters.Guided by the processing map,a hot-extruded Cu-15 Ni-8Sn alloy with a fine-grained microstructure is obtained,which shows excellent elongation of 30%and ultimate tensile strength of 910 MPa.

Microstructure and mechanical properties of TC4 titanium alloy K-TIG welded joints

The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases.

Fabrication of Co-Ni-P film with excellent wear and corrosion resistance by electroplating with supercritical CO_2 emulsion

To avoid the defects caused by the hydrogen evolution and improve the corrosion and wear properties of the electroplated films in the traditional aqueous bath electrodeposition,a supercritical carbon dioxide(Sc-CO2)emulsion was proposed to electrodeposite ternary nanocrystalline Co-Ni-P alloy films.Microstructure,corrosive and tribological properties of the Co-Ni-P films were investigated and compared with the ones electroplated by conventional method.The results show that the Co-Ni-P films produced with Sc-CO2assisted electrodeposition exhibit a more compact microstructure.The preferred orientation plane of hcp(110)for the Co-Ni-P films produced in conventional aqueous bath is changed to be hcp(100)for the one prepared in emulsified Sc-CO2bath.The microhardness,corrosion resistance and tribological properties of the Co-Ni-P films are substantially improved with the assistance of Sc-CO2in the electrodeposition bath.

Microstructure and high temperature tensile properties of Al-Si-Cu-Mn-Fe alloys prepared by semi-solid thixoforming

The differences in the microstructure and elevated temperature tensile properties of gravity die cast,squeeze cast,and semi-solid thixoformed Al-Si-Cu-Mn-Fe alloys after thermal exposure at 300℃were discussed.The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys,especially after thermal exposure for 100 h.The ultimate tensile strength(UTS)of semi-solid thixoformed alloys after thermal exposure at 300℃for 0.5,10 and 100 h were 181,122 and 110 MPa,respectively.The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications.The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.

One-step electrodeposition to fabricate robust superhydrophobic silver/graphene coatings with excellent stability

A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics.Silver coating was firstly deposited on thermoplastic polyurethane(TPU)elastomer rubber surface via two-component spraying technique,then the superhydrophobic surface was obtained by one-step electrodeposition of cerium compounds(CeM)and graphene nanosheets(GNS)to produce Ag/CeM/GNS composite coatings.The obtained Ag/CeM/GNS composite coatings maintained high conductivity after experiencing bending cycles and stretching cycles.Furthermore,the as-prepared Ag/CeM/GNS composite coatings showed excellent self-cleaning and anti-fouling properties,and the corrosion resistance has improved significantly compared to the original Ag coating.In addition,the Ag/CeM/GNS composite coatings could drive the circuit normally in the states of tensile,bending and twisting deformation,showing excellent mechanical stability and applicability.As a result,it is believed that the prepared Ag/CeM/GNS composite coatings with excellent conductivity and stability have promising applications for flexible electronics in harsh conditions.

Microstructure evolution and mechanical properties of Al-6.5Cu-0.6Mn-0.5Fe alloys with different Si additions

The effect of Si content on the microstructures and mechanical properties of the heat-treated Al-6.5 Cu-0.6 Mn-0.5 Fe alloy was investigated using image analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile testing.The results show that the mechanical properties of Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease slightly when the Si content is below 1.0%.This can be attributed to the comprehensive effect of microstructure evolution,including the increase of nano-sized α-Fe,the coarsened grain size,and an increase in Al2 Cu content at the grain boundary.When the Si content is 1.5%,the mechanical properties of the Al-6.5 Cu-0.6 Mn-0.5 Fe alloys decrease significantly,and this can be attributed to the agglomerated second intermetallics,which is resulted from the formation of excess Si particles.