不同环境下AlSiFeMm非晶纳米晶涂层摩擦磨损行为研究

目的研究AlSiFeMm(Mm为镍包混合稀土)非晶纳米晶涂层在干摩擦和3.5%NaCl溶液中的摩擦磨损行为。方法采用Rtec(MFT-3000)往复式磨损试验机测试涂层在干摩擦条件和有腐蚀介质条件下的摩擦磨损性能,使用LEXTOL3000-IR非接触三维表面轮廓仪测定涂层的磨损体积和磨痕的三维形貌,利用扫描电子显微镜对磨痕进行形貌观察和成分分析。结果铝基非晶纳米晶涂层的摩擦系数随着载荷的增加而不断减小。干摩擦条件下,铝基非晶纳米晶涂层的磨损率随着载荷的增加而增大,当磨损速度为10 mm/s、载荷为15 N时,涂层相对耐磨性为6061铝合金的2.5倍,其磨损机制为脆性剥落、磨粒磨损,并伴随氧化磨损。在3.5%NaCl溶液中,涂层的磨损率随着载荷的增加而逐渐降低,当磨损速度为35 mm/s、载荷为30N时,涂层的耐磨性能约为6061铝合金的8倍,其失效机制主要为剥层磨损和腐蚀磨损。结论铝基非晶纳米晶复合涂层在干摩擦和腐蚀介质中均表现出较为优异的耐磨性能,可以作为轻质合金涂层应用于表面防护领域。     

载荷和滑动速度对块体镁基非晶合金干摩擦性能的影响

目的以制备的Mg_(59.5)Cu_(22.9)Ag_(6.6)Gd_(11)块体镁基非晶合金为基础,探索法向载荷和滑动速度影响镁基非晶合金干摩擦行为的规律和机制,为进一步研究镁基非晶合金提供实验依据。方法采用UMT-2多功能摩擦磨损机,改变法向载荷和滑动速度的大小,进行摩擦磨损实验。通过白光干涉轮廓仪测出磨损轨迹的宽度和深度,再根据公式计算出磨损体积和磨损率。利用扫描电镜和EDS能谱分析磨损轨迹,揭示非晶合金的磨损机制。结果随着载荷的增加,磨损率先减小后稳定,摩擦系数略有减小。随着滑动速度的增加,磨损率先减小后增大,在相对滑动速度为120 mm/s时出现最小值。载荷小于20 N时,磨痕表面布满犁沟和小颗粒状磨屑;载荷大于20 N时,磨痕表面出现层叠状非均匀塑性变形层,对磨球表面转移膜粘连明显。滑动速度低时,磨痕表面布满犁沟,随着速度的增加,先是软化均匀流变,接着出现熔化、剥落。结论块体非晶镁基合金在低载荷下以磨粒磨损为主,还伴随着氧化、少量的粘着;载荷大于20 N时,变为粘着磨损为主。低滑动速度下以磨粒磨损为主,当滑动速度为180 mm/s时,试样表面熔化失效,磨损方式为剥落和磨粒磨损的综合。     

45钢与DC53钢的干滑动摩擦学行为

采用销盘摩擦磨损试验机研究了不同载荷下45钢与DC53钢(Cr12Mo V1)的干滑动摩擦学行为。通过SEM、XRD、SIMS等分析了45钢的磨损机理及其摩擦诱发的变形层特征。结果表明,载荷从40 N增加到60 N时,45钢销试样的磨损率增加量远大于DC53钢盘试样的磨损率增加量,载荷的变化对平均摩擦系数的大小几乎无影响;40 N载荷条件下,45钢销试样表面主要发生磨粒磨损和轻微的粘着磨损,60 N载荷条件下,45钢销试样表面主要发生粘着磨损;45钢销试样的摩擦影响层均由摩擦表层和塑性变形层组成,60 N载荷条件下销试样的塑性变形层深度大于40 N载荷条件下的销试样;45钢销试样的磨损表层出现了晶粒细化的现象,60 N载荷条件下的晶粒细化更明显;磨损表层中的细晶铁素体主要是由摩擦磨损过程中摩擦热和塑性变形共同作用导致的动态再结晶诱发的。     

38CrMoAl氮化钢表面改性层摩擦磨损性能研究

采用不同方法对38CrMoAl氮化钢进行表面改性以提高其耐磨性能,分别为N试样(物理气相沉积纳米类金刚石薄膜)、S试样(物理气相沉积TiBN涂层)、L试样(离子氮化处理得到氮化层)和A试样(阿可氮化处理得到氮化层).通过HT-600型摩擦磨损试验机测试了在干摩擦条件下四种试样的摩擦磨损性能,并用VHX-600K型光学显微镜对磨损后试件表面和横截面形貌进行观察和分析.结果表明:在本试验条件下,四种试样平均摩擦因数由小到大次序为:N试样＜S试样＜L试样＜A试样;偶件材料可以在较短时间在N试样和S试样表面形成,但在N试样表面可以稳定存在,L试样和A试样表面难以形成厚度均匀且稳定存在的转移膜;S试样磨损后局部区域出现轻微磨损现象,N试样磨损后改性层厚度均匀,改性层整体状态最好,L试样和A试样出现裂纹.裂纹扩展导致局部区域脱落严重.综合考虑N试样耐磨性能最好,其次为S试样、L试样和A试样.     

沉积气氛对电火花沉积Mo2FeB2基金属陶瓷涂层组织与性能的影响

采用电火花沉积分别在空气和氩气中制备了Mo_2FeB_2基金属陶瓷涂层,通过扫描电镜(SEM)、X射线衍射(XRD)、显微硬度计和摩擦磨损试验机研究了沉积气氛对涂层形貌、相组成、硬度和摩擦磨损性能的影响。结果表明,2种气氛中沉积所得涂层的组织结构都致密,涂层与基体间无分层,呈冶金结合的特征,但空气中沉积涂层的表面较粗糙,并发生了严重的氧化,涂层均匀性也较差。它们都主要由非晶相和马氏体相组成,但氩气中沉积的涂层含有更多的非晶相。氩气和空气中沉积涂层的最大显微硬度(HV_(0.05))分别为12 862和10 129 MPa,相差2733 MPa,前者涂层2 h的磨损量几乎仅为后者涂层的1/7,表现出更好的耐磨性。2种涂层的主要磨损机制都是疲劳磨损和磨粒磨损,但氩气中沉积涂层以疲劳磨损为主,空气中沉积涂层则以磨粒磨损为主。     

一种船用低温钢板在干态室温下的往复摩擦特性研究

目的研究新型船用低温钢板的摩擦磨损性能。方法采用UMT-2型多功能摩擦磨损实验机,测试了船用低温钢板在室温干态环境、不同载荷(10、20、30 N)、不同频率(2、5 Hz)下的往复摩擦试验行为。采用光学显微镜(OM)、扫描电子显微镜(SEM)分析了船用低温钢板的磨痕表面形貌,用光学轮廓仪分析了磨损表面轮廓,用EDS对试样磨损表面进行了成分分析。结果随着试验法向载荷从10 N增加到30 N时,船用低温钢板的摩擦系数从0.51逐渐增加到0.63,磨损率先增加后降低,再逐渐增加。在相同载荷下,摩擦系数随着往复频率的提高而降低。载荷为30 N时,往复频率为5 Hz,摩擦2 h后,磨损断面轮廓宽度和深度分别为750μm和3871 nm。接触面从磨粒磨损转向疲劳磨损,接触面出现氧化层、表面硬化层和转移层。结论载荷较低时,船用低温钢磨损主要为氧化磨损和疲劳磨损;载荷增大时,接触面磨损出现疲劳磨损。同等载荷下,摩擦系数会随着移动速度的提高有所下降,接触面在摩擦热作用下形成的金属膜有助于降低表面粗糙度,减小摩擦系数。     

原位合成Al2O3增强铝基复合材料的摩擦磨损性能

通过采用粉末冶金和原位合成技术相结合的近净成形技术制备Al-5％Si-Al2O3复合材料,并运用M一2000摩擦磨损试验机对该复合材料的摩擦磨损性能进行研究。通过单一变量比较法分析载荷和滑动速度对Al-5％Si-Al2O3复合材料摩擦磨损性能的影响,同时对长时间连续磨损下该材料的摩擦性能进行研究。通过扫描电子显微镜对Al-5％Si-Al2O3复合材料的磨损表面进行观察,并分析其磨损机制。结果表明,随着载荷的增大,试样的磨损量和摩擦因数均增加;随着滑动速度的增大,试样表面的升温使得产生氧化层的速率增加,试样的磨损量和摩擦因数均减少。在长时间的连续磨损过程中,由于初始时发生粘着磨损,试样的摩擦因数随着滑动距离的增大而增大。然后,试样表面氧化层的形成和破坏趋于动态平衡,试样表面相对稳定,其摩擦因数也随之趋于平稳。铝基复合材料的磨损机制主要为磨粒磨损、粘着磨损和氧化磨损。     

硅酸盐粉体作为润滑油添加剂对摩擦副耐磨性的影响研究*

采用MM200摩擦磨损试验机研究了45^#钢-45^#钢摩擦副在含蛇纹石硅酸盐油润滑下的摩擦学行为，借助SEM及EDAX测试分析了自修复膜层的表面形貌及表面成分组成。结果表明：润滑油中添加硅酸盐蛇纹石粉体，在摩擦磨损初期，下试样的失重随磨损时间增加而增加；在试验时间为20h时，试样失重达到最大值，随后试样的失萤反而减小。在载荷600N、试验时间30h摩擦磨损后，在金属表面形成自修复保护膜，弥补了试样的部分失重；自修复膜层表面比较平整光滑，无明显的磨损划痕和犁沟，自修复膜层阻碍了金属摩擦表面的直接接触，有效地降低了金属摩擦副的磨损；自修复膜层与金属基体结合紧密，无明显的界面，膜层的厚度最大为8μm。     

CrN涂层对中碳轴承钢摩擦磨损性能的影响

为了改善钟形壳用中碳轴承钢的耐磨性能,采用磁控溅射技术在中碳轴承钢表面制备了CrN涂层。采用扫描电镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪和摩擦磨损试验机等对比分析了有无涂层的中碳轴承钢的微观形貌、力学性能和摩擦磨损性能。结果表明:中碳轴承钢热处理后的组织为回火马氏体,硬度为589. 2 HV0. 5,表面沉积CrN涂层后,硬度达到了756. 9 HV0. 5。该涂层由CrN和Cr_2N相构成,结构致密,厚度约5. 891μm。在相同摩擦磨损条件下,涂层试样比无涂层试样的磨损量减少了约35. 6%。涂层试样的主要磨损机制为氧化黏着磨损,而无涂层试样则为氧化黏着磨损和磨粒磨损。     

磨料水射流-离子氮化复合处理对316不锈钢表面摩擦性能的影响

目的研究磨料水射流-离子渗氮复合处理对316不锈钢摩擦学性能的影响。方法采用磨料水射流、离子氮化技术分别在316不锈钢表面进行喷丸(WJ-316SS)、渗氮(PN-316SS)、喷丸+渗氮(WJ-PN-316SS)表面强化处理,并采用扫描电镜(SEM)、X射线衍射仪(XRD)、洛氏硬度计、粗糙度测试仪、超景深显微镜、划痕仪和摩擦磨损仪等研究复合处理试样的表面形貌、表层相结构与韧性,并讨论了不同表面处理试样的力学性能以及在干摩擦条件下的摩擦学行为。结果复合处理后的试样表面形成了连续密排的凹槽织构,表面改性层含有Fe_2N、Cr_2N、CrN等化合物,离子渗氮层厚度大约为10μm,表面显微硬度(79HRC)和表面粗糙度(1.10μm)高于单一表面处理试样。在与Si_3N_4摩擦配副进行干摩擦的实验中,316SS、WJ-316SS、PN-316SS的摩擦因数分别为0.8、0.4、0.5,磨损质量分别为7.1、3.3、3.7 mg。而WJ-PN-316SS的摩擦因数在0.25附近波动,磨损质量为0.3 mg,明显低于单一表面处理试样,耐磨性能更加优异,其磨损机理主要为疲劳磨损和氧化磨损。结论磨料水射流-离子渗氮复合处理能显著改善316不锈钢的摩擦学性能。     

Tribological behaviors of Zr-based bulk metallic glass versus Zr-based bulk metallic glass under relative heavy loads

As a novel engineering material, bulk metallic glass (BMG) has received much attention. However, the knowledge concerning the tribological behavior of BMG versus BMG under relatively heavy loads is still insufficient. In this study, Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 metallic glass pins and discs were prepared by copper-mold suction casting. The dry sliding friction and the wear characteristics of the as-cast Zr-based BMG versus Zr-based BMG were tested under loads of 100, 125 and 150 N, respectively, using a pin-on-disc tribological apparatus at room temperature. The worn surfaces were studied by scanning electron microscopy in order to identify the wear mechanisms. The results showed that both the coefficient of friction and the wear rate increased with both the normal load and the rotational sliding velocity. X-ray diffraction patterns recorded after the tribological experiments indicated that no sliding-induced crystallization occurred. Transmission electron microscopy was also used to confirm the amorphous of the BMGs after sliding tests. In addition, the wear mechanisms changed with the experimental conditions. For a normal load of 100 N, the main mechanisms were abrasive wear, slight grooves and micro-cracks. For higher loads, adhesive wear was predominant, accompanied by abrasive wear and deeper grooves and more micro-cracks. When the rotational sliding velocity was increased, the dominant wear changed from slight grooves to viscous flow and adhesive wear.     

Tribological studies of a Zr-based bulk metallic glass

In the present study, the tribological behavior of a Zr_52.5Cu_17.9Ni_14.6Ti₅Al₁₀ bulk metallic glass (BMG) was investigated using pin-on-disk sliding measurements under an argon atmosphere, rubbing against a type 303 stainless steel counterface. The tested pins and disk were examined using X-ray diffractometry, optical microscopy, profilometry, scanning electron microscopy and transmission electron microscopy. The results showed that the wear of the BMG pins was substantially larger compared with previous tests performed against a zirconia counterface. Strain softening was found in the near-surface region of the glassy pin due to the highly localized shearing. Frictional heating contributed to the occurrence of viscous flow and material transfer on the worn surface of the wear pin and the disk, respectively. Thus, the pin exhibited a severe adhesive-dominated sliding wear.     

Enhanced wear resistivity of a Zr-based bulk metallic glass processed by high-pressure torsion under reciprocating dry conditions

Wear properties of bulk metallic glasses (BMGs) are important for industrial applications as much as strength and ductility. Free volume of BMGs is a significant factor which decides wear mechanism and resistance. Increased free volume of a Zr₅₅Al₁₀Ni₅Cu₃₀ BMG processed by high-pressure torsion (HPT) affected wear resistance under dry reciprocating conditions. Two- and three-body abrasive wear as well as the delamination of oxide layers simultaneously operated during the wear tests of both as-cast and HPT-processed BMG (HPT-BMG). However, the HPT- BMG had a larger area of the oxide layers on a worn surface compared to the as-cast BMG at the early stage of the wear tests. The increased free volume by the HPT process resulted in ductile plastic deformation, prohibited crack propagation, and delayed delamination of the oxide layers. Therefore, the HPT-BMG had thicker oxide layers, which acted as an adequate protection and increased wear properties of the Zr-based BMG.     

The effects of stoichiometry on the dry sliding wear of FeAl

The effects of alloy stoichiometry on the dry sliding wear behavior of B2-structured FeAl were investigated using four different FeAl alloys containing 40, 43, 48, and 50 at.% Al. Room temperature pin-on-disk tribotests were performed against an yttria-stabilized zirconia counterface in four different environments: air, oxygen, 4% hydrogen in nitrogen, and argon. It was found that the alloys had lower wear rates in both oxygen-free and water vapor-free environments, where the wear loss was roughly inversely related to the hardness. Interestingly, the wear rates were little affected by the presence of molecular hydrogen. In oxygen- or water vapor-containing environments, the effects of the environment predominated over any effects from the mechanical properties of the alloys. The tips of the worn pins were examined using both scanning electron microscopy and transmission electron microscopy, the latter using specimens produced by focused ion beam milling. Zirconia particles were found to be embedded in a tribolayer on the worn tips of the pins. The results indicate that both two-body and three-body abrasive wear, as well as plastic deformation and delamination were the main wear mechanisms. The abrasive particles largely consisted of the counterface material.     

Cu/Ag/石墨复合涂层电滑动摩擦磨损行为研究

运用等离子喷涂技术在C45E4基材上制备了Cu/Ag/石墨复合材料涂层。利用HST-100销-盘式摩擦磨损试验机,研究了不同电流强度对Cu/Ag/石墨复合材料涂层摩擦磨损行为的影响。利用场发射扫描电镜、能谱仪和X射线衍射技术对涂层结构、相组成、磨损形貌和磨屑进行了表征。涂层结构分析表明：Cu/Ag 合金形成了连续的导电通道而沉积的石墨颗粒具有明显的平行于基材的取向。随着电流从0增加到50A,复合材料涂层的磨损率随之增大,而且磨损率与施加的接触压力和滑动速度有紧密的联系。在本实验中,观察到在相同接触压力和滑动速度条件下,摩擦系数与电流强度几乎无关的现象。石墨转移膜和氧化物层是形成稳定滑动的主要因素。没有电流时,磨损机理主要是磨粒磨损,但随着电流的增强,电磨损变为滑动过程中复合材料的主要磨损机理。     

Chip formation, cutting forces, and tool wear in turning of Zr-based bulk metallic glass

The chip light emission and morphology, cutting forces, surface roughness, and tool wear in turning of Zr-based bulk metallic glass (BMG) material are investigated. Machining results are compared with those of aluminum 6061-T6 and AISI 304 stainless steel under the same cutting conditions. This study demonstrates that the high cutting speeds and tools with low thermal conductivity and rake angle activate the light emission and chip oxidation in BMG machining. For the BMG chip without light emission, serrated chip formation with adiabatic shear band and void formation is observed. The cutting force analysis further correlates the chip oxidation and specific cutting energy and shows the significant reduction of cutting forces for machining BMG at high cutting speeds. The machined surface of BMG has better surface roughness than that of the other two work materials. Some tool wear features, including the welding of chip to the tool tip and chipping of the polycrystalline cubic boron nitride (PCBN) tool edge, are reported for turning of BMG. This study concludes that BMG can be machined with good surface roughness using conventional cutting tools.     

纳米WC增强Ni基合金喷熔层组织结构与抗磨粒磨损特性

目的研究纳米WC对Ni基合金喷熔层抗磨粒磨损性能的影响。方法采用扫描电镜、X射线衍射分析了氧乙炔火焰喷熔Ni基合金层和两种不同结构WC增强Ni基合金喷熔层的微观组织和相结构,并通过磨粒磨损试验平台对三种涂层进行磨损性能测试。结果纳米WC粉末的加入,能有效提高喷熔层的宏观硬度。通过组织分析得出纳米WC增强Ni基喷熔层中除含有γ-(Ni,Cr)固溶体、Cr的碳化物、硼化物以及微米级WC颗粒之外,还含有一定量的纳米WC团聚体和少量高硬度的W_2C相。磨粒磨损实验结果显示,纳米WC增强Ni基喷熔层的磨损失重分别为Ni60和NiWC35涂层失重的56%和73%。对比磨损后涂层的表面微观形貌可知,纳米WC颗粒在涂层中能有效降低磨粒压入喷熔层的深度,从而控制磨粒对喷熔层的犁削量。结论纳米WC增强Ni基合金喷熔层中含有的γ-(Cr,Ni)固溶体、Cr_(23)C_6、Cr_7C_3、Cr_3Ni_2及未熔化的WC颗粒和WC脱碳形成的W_2C等硬质相,使镍基自熔合金涂层的硬度有较大提高,同时也大大提高了涂层的抗磨粒磨损性能。     

温度和载荷对TC4合金磨损性能的影响

采用MG-2000型销盘式高温磨损试验机对TC4合金在环境温度为25~600℃、载荷为50~250 N时的磨损性能进行了研究。利用SEM、EDS和XRD等对试样磨面和剖面的形貌、成分及结构进行了观察与分析。实验结果表明,在25~300℃,TC4合金的磨损率随着温度的升高而升高。磨面呈犁沟及黏着痕迹,磨损机制为黏着磨损和磨粒磨损。在400℃时,磨面局部被摩擦氧化层所覆盖,磨损率随着载荷的增加缓慢下降,磨损机制为黏着磨损、磨粒磨损和氧化磨损。在500~600℃,磨面大部分被摩擦氧化层所覆盖,磨损率很低且随载荷变化很小,磨损机制为氧化磨损。可见,TC4合金在500~600℃具有优异的耐磨性能。