金属表面质量对PTFE复合材料摩擦性能的影响

采用冷压-烧结成型工艺制备了3种聚四氟乙烯复合材料,制备了3种不同表面质量的45#钢、铝合金及其表面阳极氧化的摩擦对偶件,考察了聚四氟乙烯复合材料与对偶件配副的摩擦磨损性能,用扫描电子显微镜观察了复合材料磨损后的表面形貌。结果表明:金属表面粗糙度Ra、Ry较大,表面接触区域Mr较小时,聚四氟乙烯复合材料干摩擦因数和磨痕宽度较大;金属表面粗糙度Ra、Ry较小,表面接触区域Mr较大时,聚四氟乙烯复合材料干摩擦因数和磨痕宽度较小。金属表面粗糙度Ra、Ry较小,表面接触区域Mr较大时,在干摩擦剧烈磨损阶段,摩擦表面接触区域产生很大的应力和变形,形成微观的赫兹应力分布,导致了聚四氟乙烯复合材料微切削磨损、疲劳磨损、磨粒磨损和黏着磨损。     

电刷镀Cu/Ni纳米多层膜的微动磨损性能

用球-盘磨损装置研究了电刷镀Cu／Ni纳米多层膜的摩擦磨损性能,采用SEM观察了其表面和截面形貌,并比较了该复合膜层与纯镍镀层的摩擦系数随时间的变化趋势、磨损量以及磨痕形貌。结果表明,该纳米多层膜具有较好的抗微动磨损性能,且晶粒细小,组织致密,界面清晰,各子层厚度均匀;该镀层与纯镍镀层的摩擦系数在达到稳定值后无明显变化;该多层膜的微动磨损方式为粘着疲劳磨损。     

干摩擦条件下丁腈橡胶和氟橡胶摩擦磨损行为研究

采用微机控制磨粒磨损试验机研究丁腈橡胶（NBR）和氟橡胶（FKM）与45#钢配副在干摩擦条件下的摩擦磨损行为,并对NBR和FKM的磨痕表面形貌、元素含量和表面官能团变化进行分析。结果表明：当转速较低时,NBR和FKM均以磨粒磨损（微切削）为主;当转速大于200 r·min^-1时,NBR磨痕表面出现胶合现象,表现为粘着磨损,FKM的耐磨性能优于NBR。NBR和FKM的磨粒磨损机理相似,主要物理过程为宏观分层剥落;当转速较高时,橡胶/钢副接触面发生了粘着转移,在钢环表面形成了转移膜。在干摩擦过程中NBR和FKM的分子链发生断裂形成大分子自由基,大分子自由基异构化并发生氧化反应。     

油气管道X80管线钢的干式滑动摩擦磨损特性研究

以球-盘接触方式,通过X80管线钢(评价材料)与淬硬冷作模具钢Cr12Mo V(62±1HRC,对偶材料)的干式滑动摩擦磨损试验,揭示了滑动速度和法向载荷对摩擦特性的影响规律,分析了X80管线钢磨损表面的磨损机理。结果表明,滑动速度在0.05~0.15m/s范围时对摩擦系数的影响有限;当滑动速度在0.15~0.25m/s范围时对摩擦系数的影响较大。当载荷在1~3N范围时对摩擦系数的影响较大;载荷在3~9N范围对摩擦系数基本无影响。X80管线钢的磨损率随滑动速度的增大以线性方式增大,而随载荷的增大以非线性方式升高,载荷越大,影响越显著。X80管线钢的磨损以磨粒磨损与粘结磨损为主,疲劳磨损为辅。     

玻璃纤维填充改性PTFE复合材料的摩擦磨损性能

为改善聚四氟乙烯(PTFE)高磨耗的缺点,通过冷压烧结成型工艺制备了玻璃纤维(GF)填充改性PTFE复合材料,探究了不同GF添加比例的PTFE/GF复合材料在不同转速下的摩擦磨损情况。采用三维视频显微镜观察了样品的表面磨痕深度,并借助扫描电子显微镜观察摩擦表面形貌同时分析磨损机理。结果表明,填充GF后的PTFE复合材料其摩擦系数虽有一定程度的升高,但其体积磨损率却大幅降低。当GF质量分数为20%时,复合材料的体积磨损率降到最低,并在转速为80 r/min时较纯PTFE降低了93.56%。观察分析微观形貌发现,随着GF含量的增大,复合材料的磨损机理逐渐由纯PTFE的犁耕磨损和粘着磨损向磨粒磨损转变,当GF含量为25%时,出现轻微的疲劳磨损。     

聚丙烯腈纤维/MC尼龙6原位复合材料摩擦磨损性能研究

本文利用己内酰胺的阴离子原位聚合方法制备了聚丙烯腈纤维/MC尼龙6原位复合材料。对复合材料的摩擦磨损性能进行了测试,通过DSC、SEM等测试手段对复合材料的摩擦磨损机理进行探讨。结果表明原位复合材料的磨损机理是以磨粒磨损为主,同时还有粘着磨损和疲劳磨损。摩擦温度是摩擦系数大小的影响因素。原位复合材料的摩擦系数随载荷的增加而减小,磨损量随着载荷的增加而增加。在低载荷条件下,原位复合材料的摩擦系数大于MC尼龙6,当载荷增加时,聚合物表面软化熔融,起到了润滑作用使得复合材料的摩擦系数下降。     

原位合成碳化硅-硼化钛复相陶瓷的高温摩擦性能及其磨损机理

以SiC为基体,用TiC和B4C为原料反应生成TiB2,原位合成了SiC-TiB2复相陶瓷.通过测试SiC和SiC-TiB2的高温摩擦系数和比磨损率与温度、外加载荷的关系,研究了SiC-TiB2复相陶瓷的高温摩擦学性能.在空气中,外加载荷为0.2 MPa,摩擦速度为0.3 m/s时,SiC-TiB2复相陶瓷自对偶(SiC-TiB2/SiC-TiB2)高温摩擦呈现较好的高温自润滑性能.温度对SiC-TiB2/SiC-TiB2摩擦系数和比磨损率的影响与载荷有关.载荷为0.4 MPa时,比磨损率最大.用X射线衍射测试了SiC-TiB2/SiC-TiB2磨屑的组成,用扫描电子镜观察了SiC-TiB2/SiC-TiB2磨损断面,发现高温摩擦氧化是TiB2-SiC/SiC-TiB2磨损的主要机理.磨损断面包含摩擦氧化层、过渡层和基体亚表面3层,氧化层和过渡层接触紧密.磨屑具有典型包裹结构,其主要氧化物是无定形氧化硅.平滑的氧化层改进了摩擦表面的塑变性能,缓冲了摩擦应力,减小了高温比磨损率.     

纳米TiO2-超高分子量聚乙烯复合材料的摩擦学特性

利用MM-200型摩擦磨损实验机,考察了纳米TiO2增强超高分子量聚乙烯（UHMWPE）复合材料在生理盐水润滑下,与Co—Cr—Mo合金对摩时的摩擦磨损性能,用光学显微镜观察了材料摩擦表面磨痕形貌。结果表明,适当填充纳米TiO2可提高UHMWPE的硬度,显著降低摩擦系数,增强耐磨性。UHMWPE的磨损主要表现为粘着、犁沟及塑性变形,TiO2-UHMWPE复合材料的磨损表现为轻微疲劳磨损。     

竹炭/碳纤维增强树脂基摩擦材料摩擦磨损性能

采用腰果壳油改性酚醛树脂和丁腈橡胶为粘结剂,具有高弹性模量和高强度的碳纤维为增强纤维,竹炭、重晶石和蛭石等为填料,采用热压成型工艺制备树脂基摩擦材料,研究了竹炭含量对摩擦材料的剪切强度、密度和摩擦磨损性能的影响,借助扫描电镜观察磨损表面形貌并分析磨损机理。结果表明:随着竹炭含量的增加,材料的剪切强度和密度相应减少;添加竹炭能明显提升在250℃和350℃下的摩擦系数,对于100℃下的摩擦系数影响较小;增加竹炭含量,材料的磨损率逐渐变大,磨损机制由单一磨粒磨损向黏着磨损和磨粒磨损的复合磨损机制转变。     

聚甲亚胺改性MC尼龙复合材料干摩擦磨损特性

通过原位聚合法制备出由两种不同化学结构聚甲亚胺改性的MC尼龙复合材料,利用环-块形式对比研究了与45#钢环对磨时在不同磨损条件下的干摩擦磨损性能,并利用扫描电子显微镜对其磨损机理进行了分析。结果表明:在所测试的条件下,MC尼龙及其复合材料的摩擦系数随载荷的增加而逐步下降,聚甲亚胺在大多数条件下能够改善复合材料的耐磨损性能;在低速低载时,MC尼龙及其复合材料的磨损表面发生了明显的塑性形变,磨损机理为磨粒磨损和粘着磨损;高速高载时,磨损机理主要为粘着磨损和疲劳磨损。     

试验环境温度对小牛血清边界润滑条件下超高分子量聚乙烯往复磨损行为的影响

采用自行研制的往复摩擦磨损试验机,在法向栽荷为50 N、往复频率1 Hz、摩擦副接触形式为圆环外圆周/平面、初始线接触长度为6 mm,相对湿度为80%、体积含量25%小牛血清去离子水溶液边界润滑的试验条件下,研究试验环境温度对超高分子量聚乙烯(UHMWPE)与铁合金配副的往复摩擦磨损性能的影响,并利用扫描电子显微镜观察37℃时磨损表面形貌.结果表明:试验环境温度θ由10℃升高至30℃,UHMWPE/钛合金摩擦副的平均摩擦因数μa呈明显下降趋势,由30℃升高至37℃时,μa开始缓慢上升,UHMWPE的体积磨损量Wv随试验环境温度θ变化也呈现相似的规律;磨损机制主要表现为磨料磨损.     

Tribological Characteristics of α-Alumina at Elevated Temperatures

The tribological characteristics of a high-purity α-alumina sliding on a similar material under unlubricated conditions are divided into four distinct regimes. At low temperatures, T < 200°C, tribochemical reactions between the alumina surface and water vapor in the environment control the tribological performance. The coefficient of friction in this temperature range is approximately 0.40 and the wear coefficient is less than 10⁻⁶, independent of contact load. At intermediate temperatures, 200°C < T < 800°C, the wear behavior depends on the contact load. At low loads, wear occurs by plastic flow and plowing; the coefficient of friction is approximately 0.60 and the wear coefficient is less than 10⁻⁶. At loads larger than a threshold value, severe wear occurs by intergranular fracture. The coefficient of friction increases to 0.85 and the wear coefficient increases to a value greater than 10⁻⁴. At temperatures above 800°C, formation of a silicon-rich layer on the wear track by diffusion and viscous flow of the grain-boundary phase reduces the coefficient of friction to 0.40, and the wear coefficient is reduced to a value less than 10⁻⁶. The results of the wear tests and observations of the fundamental mechanisms controlling the tribological behavior of this material are consolidated in a simple wear transition diagram.     

Investigation of tribological properties of micro-arc oxidation ceramic coating on Mg alloy under dry sliding condition

To enhance wear resistance of Mg alloy, micro-arc oxidation (MAO) ceramic coatings on Mg substrate were prepared in silicate electrolyte under various currents. It was found that the surface roughness and thickness of MAO coating were increased with the increase of current. The dry tribological tests showed that the friction coefficient and wear resistance of thicker coatings (obtained under currents of 3?A and 4?A) were much higher than that of Mg alloy and the thin coating (obtained under current of 2?A), meanwhile the lifetime of the coating obtained under 4?A was longer than the other coatings under higher load. The wear type of thin MAO coating was slight abrasive wear under low load, whereas translated to severe adhesive wear under high load. While the main wear mechanism of thick MAO coating was slight abrasive wear or scratch under the given test condition, which was attributed to the thick intermediate layer improved load support for the soft substrate. The tribological study indicated that the MAO coating obtained under 4?A current had better wear resistance and life time due to its compact microstructure and thickness.     

PA6/纳米Al_2O_3复合材料摩擦性能的研究

研究了纳米Al2 O3 填充PA6复合材料的摩擦性能。通过分析纳米Al2 O3 含量、载荷对材料摩擦系数和耐磨性能的影响,得到复合材料中纳米Al2 O3 为 6wt%时,材料的摩擦性能最好。通过SEM图片分析试件摩擦表面形貌,发现复合材料的磨损机理从纯PA6材料的粘着磨损转为轻微的磨粒磨损和粘着磨损     

温度对酚醛树脂/丁腈橡胶复合材料摩擦学性能的影响

采用机械共混法将酚醛树脂（PF）与丁腈橡胶（NBR）进行混合而制得PF/NBR复合材料,研究了PF用量对NBR的拉伸性能、撕裂性能及硬度的影响,使用多功能材料表面性能综合测试仪、三维表面形貌仪和扫描电子显微镜对力学性能最优的PF/NBR复合材料试样A 2（添加5份PF）在不同温度下的摩擦性能进行了探究,并与未添加PF的试样A 0进行了对比,此外还对PF/NBR复合材料的磨损机理进行了初步分析。结果表明,当温度超过75 ℃时,试样A 0的摩擦系数曲线整体呈持续上升的趋势,同时其表面有较多孔洞,分子间结合力下降,耐磨性变差,而试样A 2的摩擦系数则基本保持稳定,磨损行为表明其磨损机理由磨粒磨损逐渐转变为黏着磨损;相对于试样A 0而言,试样A 2在高温下仍能保持较好的摩擦性能。     

热处理温度对C／C复合材料摩擦磨损性能的影响

利用销一盘式摩擦磨损试验机研究了不同热处理温度制备C／C复合材料与GCrl5钢配副在油润滑务件下的摩擦磨损行为。结果表明,在油润滑条件下,材料摩擦系数低,其值在0．06～0．17范围内,磨损率在（1．03～2．56）×10^4mg／N·m范围,其中2100℃热处理的材料具有最低的摩擦系数和磨损率。在摩擦试验过程中,2000℃以上热处理的材料可以形成完整致密的摩擦膜,能起到润滑作用。结果还表明,随热处理温度的提高,材料石墨化程度提高,硬度降低,其磨损机制以磨粒磨损为主转向以疲劳磨损和粘着磨损占据主导地位。     

Tribological Behavior of Al-SiC Metal Matrix Composite Under Dry,Aqueous and Alkaline Medium

The present study considers friction and wear behavior of aluminum matrix composites reinforced with SiC particles under three different working environments, viz., dry condition, aqueous medium and alkaline medium. The experiments are conducted with a pin-on-disk tribotester where the composite specimen slides against an alumina disk under the application of varying normal load and sliding speed. It is observed that wear increases with increase in applied load and sliding speed for all three working environments and the maximum wear occurs in the case of the alkaline medium followed by the aqueous medium and the dry condition. In general, the friction coefficient decreases with increase in applied normal load. The microstructure analysis of the worn sliding surface is done with the help of a scanning electron microscope and energy dispersive X-ray analysis. It is seen that the wear mechanism in dry condition is dominated by adhesive and abrasive wear while both mechanical and corrosive wear occur in corrosive environments.     

Tribological Performance of Bamboo Fabric Reinforced Epoxy Composites

Bamboo fiber is one of the strongest natural fibers with high strength-to-weight and stiffness-to-weight ratios and can be used economically for manufacturing fiber-reinforced composites. In this paper, bamboo fabric-reinforced epoxy composite is manufactured and its tribological properties for load-bearing applications are investigated. Sliding wear tests are conducted using a linear reciprocating tribometer and the effect of dry and lubricated contact conditions, applied load, sliding speed, temperature, and woven fabric direction on the coefficient of friction and wear rate are investigated. A scanning electron microscope is used to define the wear mechanisms at room and elevated temperatures. It is observed that the fabric orientation influences the mechanical and tribological performances of the composite material. Wear rate increases at higher loads and working temperatures; however, the effect of sliding speed is not remarkable, especially under lubricated contact conditions. The results present in this paper can be used for designing bamboo-reinforced epoxy composites for load-bearing applications, under different working conditions.     

Frictional Properties of TiN – AlN-Based Hot-Pressed Composites

The tribological properties of TiN – AlN-based composites forming a friction couple with 65G-grade steel under lubricant-free conditions are studied in the speed range of 4–16 m/sec and pressure of 0.5 – 2.0 MPa. The increase both in speed and load causes a decrease in the coefficient of friction. For a speed of 16 m/sec and pressure of 2.0 MPa, the coefficient of friction is 0.16 – 0.11, and the linear wear is 6.0 – 5.7 m/km. The superior tribological properties of TiN – AlN composites are related to the high mechanical properties of these materials. During friction at high speeds and loads, the abrasive and adhesive wear decreases owing to the oxide films that form on the surface and play the role of a solid lubricant and thus reduce friction loss.     

Tribological performance of SiC coating for carbon/carbon composites at elevated temperatures

SiC coating was deposited on carbon/carbon (C/C) composites by chemical vapor deposition (CVD). The effects of elevated temperatures on tribological performance of SiC coating were investigated. The related microstructure and wear mechanism were analyzed. The results show that the as-deposited SiC coating consists of uniformity of β-SiC phase. The mild abrasive and slight adhesive wear were the main wear mechanisms at room temperature, and the SiC coating presented the maximum friction coefficient and the minimum wear rate. Slight oxidation of debris was occurred when the temperature rose to 300?°C. As the temperature was above 600?°C, dense oxide film formed on the worn surface. The silica tribo-film replaced the mechanical fracture and dominated the frication process. However, the aggravation of oxidation at elevated temperatures was responsible for the decrease of friction coefficient and the deterioration of wear rate. The SiC coating presented the minimum friction coefficient and the maximum wear rate when the temperature was 800?°C.