Fretting wear and friction oxidation behavior of 0Cr20Ni32AlTi alloy at high temperature

The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C.Wear scar and debris were analyzed systematically by scanning electron microscopy and X-ray photoelectron spectroscopy.The results show that the friction logs are mixed fretting regime and gross slip regime with the magnitudes of displacement of 10 and 20 μm,respectively.Severe wear and friction oxidation occur on the material surface.A large number of granular debris produced in the fretting process can be easily congregated and adhered at the contact zone after repeated crushes.The resultant of friction oxidation is mainly composed of Fe3O4,Fe2O3,Cr2O3 and NiO.Temperature and friction are the major factors affecting the oxidation reaction rate.The fretting friction effect can enhance the oxidation reaction activity of surface atoms of 0Cr20Ni32AlTi alloy and reduce the oxidation activation energy.As result,the oxidation reaction rate is accelerated.

Friction and Wear Properties of TiAl and Ti_2AlN/TiAl Composites at High Temperature

The high-temperature friction and wear properties of TiAl alloys and Ti2AlN/TiAl composites （TTC） in contact with nickel-based superalloy were studied. The results showed that, at 800 and 1 000 ℃, the coefficient of the friction （COF） decreased with the increase of sliding velocity and the wear loss of the TTC decreased with the increase of volume fraction of Ti2AlN. The wear mechanisms of the pairs are adhesive wear and the wear debris mainly comes from the contacting nickel-based superalloy. The intergranular fracture and the cracking of the phase boundary in the lamellar structure are the wear mode of TiAl alloy. The wear mode of TTC is phase boundary fracture and adhesive spalling. The abrasive resistance of TTC is slightly higher than that of TiAl alloy.

High-temperature frictional wear behavior of MCrAlY-based coatings deposited by atmosphere plasma spraying

Al2O3-r2O03/NiCoCrAIYTa coatings were prepared via atmosphere plasma spraying （APS）. The microstructure and phase com- position of the coatings were analyzed by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, laser confocal scanning microsco- py （LSCM）, and transmission electron microscopy （TEM）. The dry frictional wear behavior of the coatings at 500℃ in static air was inves- tigated and compared with that of 0Cr25Ni20 steel. The results show that the coatings comprise the slatted layers of oxide phases, unmelted particles, and pores. The hot abrasive resistance of the coatings is enhanced compared to that of 0Cr25Ni20, and their mass loss is approxi- mately one-fifteenth that of 0Cr25Ni20 steel. The main wear failure mechanisms of the coatings are abrasive wear, fatigue wear, and adhe- sive wear.

Tribological property and high temperature oxidation behavior of Ni-based alloy

Ni-Cr based alloys were prepared by hot-pressing the mixture of strengthening phases Mo, Al, Ti, and lubricant phase MoS2. The hardness, tribological properties as well as the high temperature oxidation properties were evaluated, The results show that the strengthening phases can improve the mechanical properties of Ni-Cr based alloy obviously, and the wear and friction properties of Ni-based alloy with strengthening phase can be improved. Its friction coefficient and wear rate rubbed with Al2O3 ceramic disk are about 0.4 and 10 -14m3/（N·m）, respectively, and the oxidation process is mainly affected by Cr2O3.

Tribological Properties of SiC/Cu Composite at High Temperature

SiC/Cu composites were prepared by hot pressing. The high temperature tribological properties of the composites were investigated. XRD, SEM techniques were carried out to characterize the samples. It is found that the friction coefficient of SiC/Cu composites increases with the increasing SiC content. The SiC reinforcement particles are worn down other than removed by pulling out during the wear test. Oxidation of Cu debris leads to the smooth contacting surface. Ring crack is formed under the cyclic wear test. The crack propagates through the damaged matrix and along the brittle interface between SiC particles and Cu matrix.

Effect of Y_(2)O_(3) on microstructure and properties of CoCrFeNiTiNb high entropy alloy coating on Ti-6Al-4V surface by laser cladding

The effects of Y_(2)O_(3) on the microstructure, microhardness, wear resistance, high-temperature oxidation resistance, hot corrosion resistance, and electrochemical corrosion behaviour of CoCrFeNiTiNb high entropy alloy coatings formed on Ti-6Al-4V alloy surfaces were studied. The results show that the addition of Y_(2)O_(3) changes the proportion of the phase but does not change its type. The average grain size is only 1/4.7 of that of the high entropy alloy(HEA) coating, and the fine-grained strengthening leads to increases in the microhardness and wear resistance of 21.8% and 26.9%, respectively. The addition of Y_(2)O_(3) enhances the denseness and bonding properties of the oxide and corrosion product layers, reducing the oxidation and hot corrosion rates by 60.3% and 40.3%, respectively. The addition of Y_(2)O_(3) doubles the corrosion resistance which is attributed to the refinement of the grains, the increased proportion of HCP and TiN, and the weakening of galvanic coupling corrosion.

32Cr3Mo1V表面激光熔覆TiC/钴基高温合金组织和性能研究

针对铝热轧辊套表面因高温摩擦磨损失效的问题,采用同轴送粉式激光熔覆在32Cr3Mo1V表面制备不同质量分数(0%、5%、10%、15%)TiC/Co-08高温耐磨熔覆涂层。分析了该熔覆层的显微组织形貌、相组成及微区成分;测试了显微硬度、高温摩擦磨损性能。结果表明,Co-08涂层主要由γ-Co及晶间碳化物组成,其磨损形式为氧化磨损和磨粒磨损。TiC添加量为5%时,晶间组织碳化物含量减少,涂层中Fe元素含量升高,涂层显微硬度降低,摩擦系数有所升高,磨损形式为粘着磨损和磨粒磨损。TiC含量≥10%时,晶间碳化物含量升高,涂层中析出细小的TiC颗粒,有效提高了涂层的显微硬度,其摩擦系数也明显降低,磨损机制主要为氧化磨损及轻微的磨粒磨损。当TiC添加量为5%时,涂层显微组织变得粗大且显微硬度及高温耐磨性均降低。随着TiC含量的继续增加,涂层中重新析出小尺寸TiC增强体,且晶间碳化物含量也有所上升,其显微硬度及高温耐磨性也随TiC含量的增加而升高。在TiC含量≥10%时,TiC/Co-08复合涂层具有良好的高温耐磨性。

枪管用环保镀层摩擦行为研究

传统枪管内膛表面采用的六价铬镀层,高温耐磨性好,但对环境污染严重。为开发环保镀层,采用超景深三维显微镜、扫描电子显微镜表征了室温和高温(400℃)摩擦磨损试样,对比分析了六价铬、三价铬、钴-镍和镍-钨四种电镀层的磨损特征。研究结果表明:在500℃定性回火后,三价铬、镍-钨、六价铬和钴-镍镀层硬度依次递减,与六价铬层相比,三价铬层脆性大,镍-钨和钴-镍镀层韧性高;室温下与H62黄铜对摩后,六价铬和三价铬镀层摩擦程度较轻,钴-镍和镍-钨镀层呈现明显粘着特征,二者摩擦系数高于两种铬层;400℃下与08Al钢对摩后,六价铬呈粘着磨损特征,摩擦程度较大;三价铬层摩擦系数相对较高;镍-钨镀层呈磨粒磨损特征,摩擦系数与六价铬接近,摩擦程度相对较轻。

Ti掺杂类金刚石薄膜的制备及其高温摩擦学性能研究

为探究金属Ti掺杂DLC薄膜在高温环境下的摩擦磨损行为,通过射频磁控溅射和直流磁控溅射混合的沉积系统制备不同Ti含量的Ti-DLC薄膜,利用SEM、XRD、Raman、纳米压痕和摩擦试验机等分析Ti含量对Ti-DLC薄膜的微观结构、力学性能及不同温度下的摩擦学性能的影响。结果表明:Ti掺杂使得Ti-DLC薄膜中sp^(3)键的占比随着Ti含量的增加先升高后下降;Ti掺杂提高了Ti-DLC薄膜的硬度和弹性模量,并一定程度上提升了Ti-DLC薄膜的膜基结合力。摩擦测试表明:在常温下,Ti-DLC薄膜的摩擦因数和磨损率随Ti含量的增加而下降,但薄膜发生明显的磨粒磨损,且磨损率略高于DLC薄膜;Ti掺杂有效地提高了DLC薄膜的热稳定性和高温摩擦学性能,在300℃的高温下,掺杂薄膜仍维持较低的摩擦因数和磨损率。

CoCrFeNiW_(x)高熵合金在室温及900℃下的摩擦磨损性能

采用真空电弧熔炼技术制备了CoCrFeNiW_(x)(x=0.25、0.5、0.75及1.0)系列高熵合金,研究了W元素含量对合金晶体结构、显微组织、力学性能以及室温与900℃摩擦学性能的影响.结果表明:合金中W含量较低时形成单相面心立方(FCC)固溶体,W含量较高时会促进金属间化合物μ相的形成,随着W含量提升,合金显微组织由FCC胞状树枝晶(x=0.25)转变为FCC树枝晶及晶间层片状(FCC+μ)共晶组织(x=0.5、0.75),最后转变为FCC基体上分布的粗大树枝状μ相(x=1.0).由于W元素的固溶强化及原位生成金属间化合物μ相的第二相强化作用,使合金的强度和硬度等力学性能显著增加的同时塑性降低.在试验载荷为10 N,滑动速度0.3 m/s的测试条件下,CoCrFeNiW_(x)系列高熵合金与Si_(3)N_(4)陶瓷球配副时的球-盘摩擦试验结果表明:W元素的添加显著改善了合金的室温耐磨性,但对摩擦系数的影响较小;而900℃摩擦时,摩擦表面形成的多元复合氧化物摩擦釉质层具有良好的减摩抗磨作用,特别是W元素氧化产生的WO_(3)显著降低了摩擦系数,从而显著提升了合金的高温摩擦磨损性能.本文中研究的系列高熵合金中,CoCrFeNiW_(0.75)高熵合金室温下的屈服强度为863 MPa,抗压强度达1 250 MPa,900℃仍能保持446 HV的硬度,并在室温及900℃下均具有良好的摩擦磨损性能,具有良好的工程应用前景.

High temperature induced“glaze”layer formed in HVOF-sprayed NiCrWMoCuCBFe coating and its wear reduction mechanism

The in-situ formation of oxides on alloy surface induced by high temperature can effectively reduce wear and resist oxidation.In consideration of the solid solution strengthening effect and great oxidation resistance of additional elements at elevated temperature,the NiCrWMoCuCBFe coating was prepared by high velocity oxygen flame(HVOF)spraying technology,and its tribological behavior was scrutinized from 25 to 800°C.By means of high temperature Vickers hardness tester and high temperature X-ray diffractometer,the mechanical properties and microstructures of NiCrWMoCuCBFe coating were measured.And the effect of the mechanical properties and microstructures of the coating on tribological performance was discussed in detail.The results showed both its friction coefficient(0.37)and wear rate(5.067×10^(−6)mm^(3)·N^(−1)·m^(−1))at 800℃ were the lowest,which was mainly related to the formation of“glaze”layer on the coating surface at high temperature.The glaze layer consisted of two parts,which were NiCr_(2)O_(4)oxide film with the ability of interlaminar slip formed in the outer layer and nano-grains existed in the inner layer.Worth mentioning,these nano-grains provided bearing capability while the oxide film was vital to reduce wear rate and friction coefficient.As the ambient temperature increased,many hard oxides were produced on the wear scars,including NiO,Cr_(2)O_(3),MoO_(3),and Mo_(2)C.They can improve tribological and mechanical properties of NiCrWMoCuCBFe coating at a wide temperature range.

喷丸对4Cr5Mo2V钢高温摩擦磨损性能的影响

对4Cr5Mo2V钢试样进行3道次复合喷丸,通过与未喷丸试样对比,研究了喷丸对试验钢表面形貌、显微组织、硬度、残余应力以及高温(100,300,500℃)摩擦磨损性能和机制的影响。结果表明:喷丸处理显著提高了试验钢表面粗糙度,使试验钢表面形成了明显的塑性变形层、硬化层与残余压应力层;在100,300,500℃下,与喷丸前相比,喷丸后试验钢的磨损率分别降低了41.8%,17.1%,63.3%,耐磨性能的提高与喷丸产生的硬化层和残余压应力层有关。在100,300℃下,喷丸前后试验钢的磨损机制均主要为黏着磨损和磨粒磨损,而当温度升高至500℃时,磨损机制为氧化磨损,喷丸试验钢仍能保持较高的硬度与残余压应力,同时表面氧化层更致密稳定,仅发生轻微氧化磨损。

石墨烯对聚脲脂高温流变和摩擦学性能的影响

目的保证轴承体系的安全性和可靠性,研究轴承润滑脂在不同工作温度下的摩擦学性能和流变学性能。方法用机械剥离法制备的石墨烯作为聚脲脂的润滑添加剂,通过四球摩擦试验机、旋转流变仪,研究石墨烯在不同工作温度下对聚脲润滑脂流变行为和摩擦学性能的影响,并通过三维轮廓仪、扫描电子显微镜和拉曼光谱仪对磨斑形貌和结构进行分析。结果添加石墨烯润滑添加剂使聚脲润滑脂的高温硬化现象明显改善,同时提高了聚脲润滑脂的结构稳定性和抗剪切能力。工作温度为75、150℃时,与空白聚脲润滑脂相比,含1.0%(质量分数)石墨烯的聚脲润滑脂润滑下的轴承钢摩擦副的摩擦系数和磨斑直径分别降低49%、20%和10%、20%。随着工作温度的升高,含石墨烯的聚脲润滑脂样品在钢滑动表面形成的沉积膜的结构有序化碳的含量稍有下降,但与空白聚脲润滑脂相比,石墨烯-聚脲润滑脂沉积膜的结构有序化碳含量高得多。结论结构有序化碳的形成对提高基础脂的减摩抗磨性能起至关重要的作用,石墨烯润滑添加剂还可以有效改善聚脲润滑脂的高温硬化性能、胶体稳定性以及稠化剂的结构稳定性。

HVOF喷涂CoCrWSi和Stellite-6涂层的结构与高温摩擦学性能研究

目的提高F92耐热钢基体在600、630℃下的高温耐磨性能。方法采用超音速火焰喷涂方法(High velocity oxy-fuel,HVOF)在F92表面制备CoCrWSi、Stellite-6两种涂层,利用扫描电子显微镜(Scanning electron microscope,SEM)和X射线衍射仪(X-ray diffraction,XRD)分析涂层的表面、截面形貌和物相组成,通过显微维氏硬度计(HV-1000STA)、高温摩擦磨损试验机(UMT-TRIBOLAB)、二维轮廓仪(TencorD-100)测定其显微硬度、高温摩擦学性能和磨痕体积。结果采用超音速火焰喷涂技术制备的CoCrWSi、Stellite-6两种涂层表面较平整,与基体结合紧密,内部组织均匀无裂纹,涂层的厚度约为200μm。XRD分析表明,CoCrWSi、Stellite-6涂层在室温下的物相都由γ(Co)、Cr_(7)C_(3)、CrSi_(2)组成。硬度及耐磨性能测试显示,CoCrWSi、Stellite-6涂层的维氏硬度相较于F92基体分别提高了3.12、2.68倍,F92耐热钢在600、630℃时的平均摩擦因数分别为0.87、0.86,体积磨损率分别为0.49×10^(-4)、1.11×10^(-4)mm^(3)/(N·m),其磨损机理主要为疲劳磨损、黏着磨损、氧化磨损。相较于基体,CoCrWSi涂层在2种温度下的平均摩擦因数分别降低了68%、71%,约为0.28、0.25,体积磨损率分别降低了约95%、97%,为0.20×10^(-5)、0.30×10^(-5)mm^(3)/(N·m),这主要归功于内部的Cr2O3、γ(Co)、Co_(3)O_(4)相在高温摩擦过程中具有良好的润滑效果。Stellite-6涂层也能在一定程度上改善基体的高温耐磨性能,其平均摩擦因数为0.85、0.71,体积磨损率为0.32×10^(-4)、0.57×10^(-4)mm^(3)/(N·m)。2种涂层的主要磨损机理均为磨粒磨损和黏着磨损。结论采用超音速火焰喷涂制备的CoCrWSi、Stellite-6涂层可以改善F92耐热钢在600、630℃下的耐高温滑动磨损性能,且CoCrWSi涂层的防护效果更佳。

高温下氮化硅陶瓷摩擦磨损性能的演变及机理研究

Si_(3)N_(4)陶瓷因具有耐高温、耐腐蚀、耐磨损、高硬度等特点,在高温耐磨损领域的应用备受关注。本文研究了高温下Si_(3)N_(4)陶瓷与C/SiC陶瓷或GH214合金摩擦时的平面摩擦磨损性能及磨损机理。结果表明:Si_(3)N_(4)陶瓷和C/SiC陶瓷对磨时,随着温度升高,摩擦系数先增大后减小;当温度为1200℃时,Si_(3)N_(4)陶瓷平均摩擦系数低于0.4,且其磨损表面出现磨痕、磨粒和SiO_(2)氧化膜,磨损形式主要为磨粒磨损和氧化磨损。Si_(3)N_(4)陶瓷与GH214合金对磨时,随着温度升高,摩擦系数增大,陶瓷样品表面出现明显的金属氧化物层,其磨损形式主要为粘着磨损和氧化磨损。Si_(3)N_(4)陶瓷与两种对磨材料摩擦时,氧化磨损均产生氧化膜并对Si_(3)N_(4)陶瓷均有保护和润滑作用,可有效减少Si_(3)N_(4)陶瓷基体的磨损,提高Si_(3)N_(4)陶瓷的磨损使用寿命。

爆炸喷涂AlCuFeSc准晶涂层的摩擦学性能研究

采用爆炸喷涂制备了AlCuFeSc准晶涂层,借助扫描电镜、X射线衍射对准晶涂层的微观及物相结构进行了表征,通过显微硬度计测试了准晶涂层的表面硬度,结果表明涂层与基体间结合良好,其中涂层主要由准晶相和β-AlFe组成,室温下涂层的表面硬度为569.4HV0.3,经退火处理后涂层硬度最高可达到658.33HV0.3。同时开展了在室温和700℃高温环境中,5、15、25 N不同载荷下AlCuFeSc准晶涂层的摩擦磨损性能研究,利用白光干涉仪对磨痕进行三维形貌观测并计算磨损的磨痕宽度、磨痕深度、体积损失,得出磨损率;采用SEM分析了不同实验条件下磨痕形貌的特征。结果表明,AlCuFeSc准晶涂层在不同温度及不同载荷下的耐磨系数在0.500~0.656之间(均低于基体),室温环境下准晶涂层的磨损机制随载荷增加从磨粒磨损为主转变为粘着磨损为主;高温环境下磨损机制则都以粘着磨损为主,准晶涂层对2A12基体具有良好的减摩耐磨功能。

AlCrCuFeNb_(x)NiTi高熵合金的摩擦磨损及高温氧化性能

采用真空电弧熔炼方法制备了AlCrCuFeNb_(x)NiTi高熵合金,并研究了铸态合金的组织、摩擦磨损性能和高温氧化性能。结果表明:Nb元素的添加促进了Laves相的形成,使AlCrCuFeNiTi合金的相结构由L2_(1)相、BCC相和FCC相转变为AlCrCuFeNb_(0.5)NiTi合金的L2_(1)相、Laves相和FCC相。Nb元素的添加会降低AlCrCuFeNiTi合金的耐磨性能,磨损速率从AlCrCuFeNiTi合金的1.572×10^(-5) mm^(3)/(N·m)提高到AlCrCuFeNb_(0.5)NiTi合金的4.483×10^(-5) mm^(3)/(N·m),合金的室温磨损机制均为粘着磨损。合金的氧化动力学遵循抛物线速率定律,Nb元素对AlCrCuFeNb_(x)NiTi合金高温氧化性能的影响随着温度的改变而改变,800和900℃时能提高其高温氧化性能,但1000℃时Laves相的内氧化现象严重导致其高温氧化性能恶化。

深冷处理对Al_(1.2)CrFe_(2)Ni_(2)高熵合金组织和性能的影响

采用非自耗真空电弧熔炼炉制备了Al_(1.2)CrFe_(2)Ni_(2)高熵合金,利用液氮对其进行了不同时间的深冷处理,分析了深冷处理时间对该合金微观组织和性能的影响。结果表明:随着深冷处理时间的延长,Al_(1.2)CrFe_(2)Ni_(2)高熵合金的晶粒尺寸先减小后增大,合金晶界处析出B2纳米相,其体积分数呈现先增加后减小的趋势。深冷处理对Al_(1.2)CrFe_(2)Ni_(2)高熵合金具有细晶强化和沉淀强化的作用。当深冷时间为24 h时,合金的硬度、压缩屈服强度和摩擦磨损性能均达到最大值,其硬度和屈服强度分别为HV 607.5和1 259.9 MPa,相比于铸态合金分别提升了18.7%和5.2%,其平均摩擦系数由铸态合金的0.89减小至0.66。

掺硅类金刚石薄膜的HiPIMS-MFMS共沉积制备及其高温摩擦学行为研究

元素掺杂是提高类金刚石(DLC)薄膜高温耐摩擦性能的重要途径.本文中采用高功率脉冲磁控溅射(HiPIMS)和中频磁控溅射(MFMS)复合技术在304不锈钢表面沉积具有不同Si含量的掺硅类金刚石(Si-DLC)薄膜,利用原子力显微镜、扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)、纳米压痕和UMT-TriboLab摩擦试验机等系统分析了Si含量对Si-DLC薄膜的结构、力学性能及不同温度下的摩擦学性能的影响,重点探讨了Si-DLC薄膜在高温下摩擦磨损机制.结果表明:Si-DLC薄膜中Si以四面体碳化硅的形式随机分布于无定型DLC基体中,增强薄膜的韧性.同时,Si掺杂使DLC薄膜向金刚石结构发生转变并显著提高了薄膜的硬度.摩擦结果表明,当Si原子分数为15.38%时,Si-DLC薄膜在常温下的摩擦系数和磨损率最低,同时该薄膜在300℃下能维持在较低的摩擦系数(约0.1),主要是由于Si-DLC薄膜中的四面体碳化硅结构能够提升sp^(3)键的稳定性.此外,Si-DLC薄膜中的Si在高温摩擦时会在对偶球表面形成1层SiO_(2)保护层,减缓Si-DLC薄膜和过渡层的氧化,使得薄膜能够在高温下持续润滑.当Si含量进一步增加时,Si-DLC薄膜的力学性能显著提升,然而其摩擦学性能发生明显降低,主要是当DLC薄膜中的硅含量过高时,大气环境下的高温摩擦使得薄膜内的氧化加剧,过量氧化硅的生成破坏了薄膜结构从而导致摩擦性能下降.

超声辅助激光熔覆IN 625高温合金涂层组织及性能研究

目的针对激光熔覆制备IN 625高温合金涂层时易产生缺陷和元素偏析进而导致合金性能下降的问题,提高增材制造IN 625高温合金的力学性能。方法在激光熔覆IN 625涂层的过程中施加超声振动辅助,通过物相检测和微观组织观测研究超声功率对涂层物相种类和晶体尺寸的影响;通过分析析出相含量、分布方式及析出形态,研究超声功率对元素偏析的影响;通过对显微硬度、高温耐磨性进行测试,研究超声功率对涂层力学性能的影响。结果施加超声前的涂层组织主要为方向杂乱的粗大枝晶,施加超声后的涂层物相组成未发生明显变化,但枝晶内亚晶排列紧密且尺寸明显减小;施加超声振动后的涂层析出相尺寸减小、含量下降,其中Laves相含量在施加超声后降幅较大,表明超声振动可以抑制Nb、Mo等元素的偏析;施加超声振动后涂层的显微硬度提高,磨损率明显下降,磨损机制由原来的表面疲劳磨损、黏着磨损和磨粒磨损的复杂磨损转变为磨粒磨损、黏着磨损的简单磨损。结论施加超声辅助可以有效细化IN 625涂层组织,并抑制Laves相的析出,提高涂层的硬度和耐磨性。