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 ...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.展开更多
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 o...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.展开更多
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 microsco...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.展开更多
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 wer...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 -14m3/（N·m）, respectively, and the oxidation process is mainly affected by Cr2O3.展开更多
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...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.展开更多
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 al...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.展开更多
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 ...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.展开更多
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-ra...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。展开更多
基金Project (51075342) supported by the National Natural Science Foundation of ChinaProject (2007CB714704) supported by the National Basic Research Program of China
文摘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.
文摘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.
基金financially supported by the National High-tech Research and Development Program of China(No.2012AA03A513)the Fundamental Research Funds for the Central Universities(No.N140204001)the National Natural Science Foundation of China(Nos.51371044 and 51301037)
文摘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.
文摘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 -14m3/（N·m）, respectively, and the oxidation process is mainly affected by Cr2O3.
基金Funded by the National Natural Scince Foundation of China (50972132)the Science Fund for Distinguished Young Scholars of Henan Province(512002200)
文摘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.
基金Project supported by the National Natural Science Foundation of China(51805285,51605237)the projects of Shandong Province"Youth Innovation Science and Technology Support Plan"(2021KJ026)+1 种基金the Key Research and Development Project of Shandong Province(2018GGX103031)the Natural Science Foundation of Shandong Province(ZR2021ME023)。
文摘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.
基金This work was supported by the National Natural Science Foundation of China(No.51771214)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2014378).
文摘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.
