H10Cr4Ni4Mo4V钢表面渗碳层硬度对接触疲劳寿命的影响

进行了H10Cr4Ni4Mo4V钢经渗碳热处理后，渗层表面硬度值的大小及均匀性对接触疲劳寿命的影响试验。结果表明，在渗碳表面硬度低或极其不均匀的情况下，其疲劳寿命远远低于渗层表面硬度高且均匀的试样寿命。在渗碳热处理时，渗层表面硬度值应控制在60．0～65．0HRC，且同一零件硬度差不大于2HRC。     

AZ31B镁合金表面激光合金化Al-SiC涂层制备及其性能研究

针对镁合金表面耐磨性差,采用预置粉末法对AZ31B表面进行激光合金化Al-SiC粉末实验。使用光学显微镜和扫描电子显微镜(SEM)、能谱分析仪(EDS)、摩擦磨损试验机、显微硬度计对合金化涂层的微结构、相组成及性能进行了分析研究。结果表明,强化层与基体呈冶金结合、组织均匀致密;合金化层主要由Mg17Al12、SiC、Mg2Si、Al4C5、Al2O3等相组成。涂层的显微硬度、耐磨损性能都明显高于基体。     

TiAlN涂层及微观组织结构研究

通过改变工艺参数,采用非平衡磁控溅射法在硬质合金基体上制备Ti Al N涂层来研究涂层微观结构的变化规律。经表面和断口形貌的扫描电镜结果显示,增加主因素偏压,涂层表面趋向光滑平整,结构趋向致密,表面的大颗粒数量明显减少。EDS能谱分析表明,涂层元素的含量受偏压和N2流量影响较大。XRD分析发现,膜层中有Ti Al N系和Ti N系的物相结构,Ti N/Ti Al N多层涂层主要从(111)晶面择优取向生长。     

β-Sialon/刚玉复相粉体材料的制备

研究了以硅粉、铝粉和刚玉粉为原料 ,通过对其表面作保护性处理 ,在 130 0℃的常压流动N2 氮气中合成了 β -Sialon/刚玉复相粉体材料。产物通过X射线衍射 (XRD)、扫描电镜 (SEM)和能谱 (EDS)分析 ,主晶相为 β-Sialon包覆的刚玉相 ,其显微形貌为板状和纤维状 ,此外 ,还有少量的 β -Si3 N4和α-Si3 N4。     

表面机械研磨处理后Zr-4合金的组织与性能

利用表面机械研磨处理(SMAT)技术对Zr-4合金进行了表面纳米化处理,用XRD、光学显微镜、表面粗糙度仪对经SMAT不同时间合金表层的物相组成、平均晶粒尺寸、显微组织和表面粗糙度进行了分析,并使用硬度计测试了距表面不同深度处的硬度.结果表明:经SMAT后Zr-4合金表层的物相组成未改变;SMAT 15 min后Zr-4合金表层平均晶粒尺寸达到最小约为20 nm;SMAT后合金表层出现了一定厚度的塑性变形层;SMAT 60 min后合金表层的硬度约为基体硬度的1.3倍,且沿着深度方向逐渐减小;合金表面粗糙度随SMAT时间的延长先增大后减小最后趋于平稳.     

陶瓷磨削表面变质层的产生机理

研究了陶瓷磨削表面变质层的产生机理。经扫描电镜观察发现了磨削表面非晶层的粘性行为和匀质化过程。采用物相分析和X射线衍射谱线分析证实了变质层中微晶的存在,通过能谱分析确定了非晶层的化学成分,在对玻璃相结构分析的基础上研究证实了Al 2O 3陶瓷表面变质层是由碎（微）晶和玻璃态化合物组成的塑性层,并解释了表面晶粒的碎化机理。     

TC4钛合金低压渗氮研究

为了提高表面性能,对TC4钛合金进行低压渗氮处理。通过金相显微镜、X射线衍射(XRD)及显微硬度计分析了渗氮层的组织与硬度。结果表明,TC4钛合金经低压渗氮处理后,表面物相由Ti N、Ti2Al N、Ti3Al和α-Ti组成,渗氮温度较低时,渗氮层较薄,硬度较低,随渗氮温度升高,渗氮层厚度增加,表面硬度亦随之增加,温度为820℃时,表面硬度可达800~850 HV,硬化层深度为30μm~40μm,渗氮温度继续增加,渗氮层组织变得疏松,表面硬度开始下降。     

20MnCr5钢齿轮表面渗碳层的显微组织

在930℃下对20MnCr5钢齿轮进行常规真空渗碳热处理,利用光学显微镜、扫描电镜、透射电镜、电子探针和显微硬度计等研究了渗碳层的显微组织、元素分布和显微硬度。结果表明：渗碳层表层组织由高碳针状马氏体与残余奥氏体组成,随距表面距离增大,针状马氏体向板条马氏体转变;渗碳层中还析出了条状富铬碳化物和球状富锰碳化物,碳化物呈弥散分布;渗碳层表面硬度为860 HV,远高于基体,随距表面距离增大,渗碳层硬度下降。     

精密轴承表面变质层的金相分析

本文应用显微硬度仪(КИООР显微硬度法)、金相显微镜、电子显微镜等现代金相分析手 段,对精密轴承工作表面磨削变质层的相组织变化特征进行了分析研究,并定量地测量了变质层的厚度和表面层显微硬度变化曲线,计算了表面硬度降。附图14幅,表2个。     

恒速传动装置齿轮断裂失效分析

飞机电源系统的恒速传动装置齿轮在装机使用124 h后发生断裂失效;用体视显微镜、SEM、EDS等方法进行了分析,用硬度法测定了齿轮接触面的渗碳层深度。结果表明:差动齿轮先发生早期疲劳断裂,其原因是齿根处存在尺寸较大的氧化铝夹杂物,导致应力集中形成了裂纹源,再加上齿根部位渗碳时未形成有效硬化层,导致齿根处疲劳强度大大降低,致使裂纹扩展而断裂;随后输入齿轮发生过载断裂。     

A hybrid Taguchi-artificial neural network approach to predict surface roughness during electric discharge machining of titanium alloys

In the present study, electric discharge machining process was used for machining of titanium alloys. Eight process parameters were varied during the process. Experimental results showed that current and pulse-on-time significantly affected the performance characteristics. Artificial neural network coupled with Taguchi approach was applied for optimization and prediction of surface roughness. The experimental results and the predicted results showed good agreement. SEM was used to investigate the surface integrity. Analysis for migration of different chemical elements and formation of compounds on the surface was performed using EDS and XRD pattern. The results showed that high discharge energy caused surface defects such as cracks, craters, thick recast layer, micro pores, pin holes, residual stresses and debris. Also, migration of chemical elements both from electrode and dielectric media were observed during EDS analysis. Presence of carbon was seen on the machined surface. XRD results showed formation of titanium carbide compound which precipitated on the machined surface.     

花状与球状MoS2对PAO15润滑油摩擦学性能的影响

为改善低黏度PAO15润滑油的摩擦学性能,通过水热法制备球形与花状MoS_2颗粒,采用X射线衍射仪(XRD)与扫描电子显微镜(SEM)对所制备的MoS_2颗粒进行表征。制备球形与花状MoS_2改性的PAO15油,利用四球摩擦试验机对比研究2种形貌MoS_2在不同用量条件下对PAO15油摩擦学性能的影响。采用光学显微镜、表面轮廓仪、扫描电子显微镜(SEM)与能谱仪(EDS)对磨痕表面进行表征。结果表明:制备的球形与花状MoS_2晶型均较好地符合MoS_2的晶型,掺杂至PAO15油中均能够提升其摩擦学性能,使其摩擦因数降低;随着MoS_2颗粒添加量的增加,PAO15油摩擦学性能有所提升,在质量分数为1.0%时达到最优;花状MoS_2具有更大的比表面积,其对PAO15油抗磨损性能的提升优于球形MoS_2,形成的转移膜能够更好地起到隔离摩擦表面的作用。     

An investigation into the inhomogeneity of the microstructure and mechanical properties of explosive welded H62-brass/Q235B-steel clad plates

Owing to excellent corrosion resistance, antifriction property, and economic efficiency, H62/Q235B explosive clad plates have been widely used in various fields. Therefore, detailed and systematic study into the microstructure and mechanical properties of this clad material is necessary. In this paper, the composition, microstructure, and mechanical properties of H62/Q235B explosive clad plates were analyzed by optical metallographic observation, mechanical tests, scanning electron microscope (SEM) observation, and energy dispersive spectrometer (EDS) analysis. The results showed that the bonding interface of this clad plate was periodical wavy, and the interface was bonded in two ways, one through wide transition layer with a width up to 280 μm while the other by narrow transition layer with a width less than 20 μm. The major structural components in the transition layer were supersaturated solid solutions. The microhardness of the transition layer was higher than that of base metals, and the microhardness of the base plates in the region near the bonding interface was affected by both force and heat. The shear strength of the H62/Q235B clad plate showed an obvious characteristic of anisotropy. Furthermore, the clad plate tended to crack along the transition layer when it was stretched because of the discontinuity of plastic deformation across H62/Q235B interface.     

几种纳米粒子作为润滑脂添加剂的试验研究

在MRH-3高速环块摩擦磨损实验机上,研究了纳米微粒Cu,Al,Al2O3及几组混合粒子加入到通用锂基脂中的摩擦学性能.采用扫描电子显微镜(SEM)和能量色散谱仪(EDS)分析了摩擦表面的形貌和元素组成.结果表明:含有纳米Cu,Al,Al2O3及混合粒子的润滑脂对摩擦表面均有很好的减摩、修复及抗胶合能力,其中混合粒子要比单粒子具有更好的效果.通过对实验结果的分析,纳米粒子的微滚珠、吸附、填充、焊合、软剪切层等效应是改善润滑脂摩擦学性能的主要原因,适当配比的混合粒子具有良好的协同效果.     

STEM study of Li4Ti5O12 anode material modified with Ag nanoparticles

Comprehensive scanning transmission electron microscopy (STEM) analysis of Li₄Ti₅O₁₂ (LTO) powder modified by deposited Ag nanoparticles was performed. Nanocomposite powders with Ag content of 1 wt.%, 4 wt.%, 10 wt.% were fabricated in a chemical process from suspensions of Ag and LTO. Apart from the STEM results, the presence of pure silver on the surface of the ceramic powder was confirmed by XRD and XPS analyses. The silver particles deposited on the LTO particles were characterized using the EDS mapping technique. The quantified results of the EDS mapping showed a relatively homogenous distribution of silver nanoparticles on the powder surface for every metal content. The mean diameter of the nanoparticles deposited on the LTO powder was about 4 nm in all cases. An increase in the Ag content during chemical surface modification did not cause changes in the microstructure. Focusing on an analysis of the metallic nanoparticles on the ceramic powder, electron tomography was used as an investigative technique. A very precise analysis of three‐dimensional nanostructures is desirable for a comprehensive analysis of complex materials. The quantified analysis of the Ag nanoparticles visualized using electron tomography confirmed the results of the size measurements taken from the two‐dimensional EDS maps.     

GCr15及G20CrNi2Mo轴承钢高温润滑条件下摩擦磨损性能

为了探究轴承钢在高温润滑条件下的摩擦磨损性能,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、洛氏硬度计等对GCr15高碳轴承钢和G20CrNi2Mo渗碳轴承钢组织、物相及硬度进行了表征,利用QG-700型气氛高温摩擦磨损试验机研究轴承钢材料不同条件下的高温润滑摩擦磨损性能,并分析其磨损机制.结果表明:2种轴承钢...     

预涂覆Na_2SO_4-25%NaCl盐膜的HR3C钢的高温腐蚀行为

应用X射线衍射仪(X-ray diffraction,XRD)、扫描电子显微镜(Scanning electron microscope,SEM)、能谱仪(Energy dispersive spectrometer,EDS)和电子探针显微分析(Electron probe X-ray micro-analyser,EMPA)等分析方法研究预涂覆Na_2SO_4-25%NaCl盐膜的HR3C在650℃、750℃的高温腐蚀行为。结果表明:HR3C在650℃和750℃的腐蚀动力学曲线呈"抛物线"趋势递增;腐蚀产物由表向里依次是结构疏松的Fe_2O_3与相对致密的Cr_2O_3的氧化层、尖晶石结构的复杂氧化物以及由少量Fe/Ni硫化物和孔隙组成的腐蚀影响区;提高腐蚀温度或延长腐蚀时间,氧化膜明显增厚,与基体结合程度变差甚至剥离,腐蚀影响区孔隙密度增大,深度增加。分析认为:预涂覆Na_2SO_4-25%NaCl盐膜的HR3C的高温腐蚀是氧化、硫化与氯化共同作用的结果。腐蚀初期发生高温氧化,合金表面形成具有保护性作用的氧化层;氯化反应促进了混合盐膜的熔融与挥发性物质的形成,破坏了氧化层的致密性,加速了腐蚀反应的发生;硫化作用促使合金发生内硫化。     

矿用钛合金钻杆表面复合强化与摩擦性能研究*

为提高矿用钛合金钻杆的耐磨性能,以低成本粉末冶金Ti-Al-Fe-Mo合金为研究对象,采用表面机械碾磨与固相渗碳相结合的创新方式对其表面进行复合强化处理,研究不同表面碾磨道次加渗碳处理的钛合金表面的微观组织及其显微硬度。以氮化硅球为摩擦对偶,对表面复合强化钛合金样品进行往复式滑动摩擦试验,研究钛合金表面强化层对其磨损量、摩擦因数、表面磨痕微观组织的影响规律。结果表明：表面机械碾磨方法可以在粉末钛合金表面形成梯度纳米晶结构;钛合金经过表面机械碾磨处理后可显著提高表面渗碳的深度和均匀度;经表面机械碾磨与固相渗碳复合强化处理的钛合金,其磨损量相比于单一表面渗碳的钛合金降低了近58%。表面复合强化的钛合金摩擦磨损机制以疲劳磨损、黏着磨损、氧化磨损和少量的磨粒磨损为主。     

涂层Si_3N_4陶瓷刀具切削性能研究

研究了不同切削参数对TiN+Al2O3涂层氮化硅陶瓷刀具切削灰铸铁的切削性能的影响,使用工具显微镜、SEM/EDS手段分析了涂层氮化硅刀具的磨损机理,实验还采用相同基体氮化硅陶瓷刀具做了对比分析。研究结果显示TiN+Al2O3涂层氮化硅刀具可以承受比较大的切削用量,对提高加工效率有重大意义;还发现涂层氮化硅陶瓷刀具主要失效形式为磨粒磨损,粘结磨损,在较高切削速度条件下前刀面还会出现因化学磨损形成的月牙洼。     

油润滑条件下有机物修饰纳米铜颗粒改善铁基摩擦副摩擦磨损的研究

在球盘式摩擦磨损试验机上考察了有机物修饰的纳米铜颗粒作为50CC润滑油添加剂的摩擦学性能;采用SEM和EDS分析了磨损表面形貌和表面膜元素组成。探讨了纳米铜颗粒的摩擦学作用机制：结果表明：有机物修饰的纳米铜颗粒作为添加剂能显著改善50CC润滑油的抗磨减摩性能,含0．05％纳米铜油样润滑下的摩擦因数与磨损量同基础油润滑下相比分别降低了27．6％与60％。分析后认为,纳米铜颗粒通过对摩擦表面进行修复及在摩擦表面成膜两种作用有效地改善了摩擦磨损性能。