聚酰胺/聚苯硫醚共混物摩擦学性能研究--(Ⅱ)水润滑

研究了PA66／PPS共混物在水润滑条件下的摩擦磨损性能。结果表明，共混物显著降低了PA66和PPS的摩擦系数，并远远低于干摩擦条件下的摩擦系数。其中，70％φ(PA)／30％φ（PPS)共混物在水润滑条件下的摩擦磨损性能最好。扫描电子显微镜(SEM)分析表明，水的存在抑制了聚合物在对偶钢环上形成转移膜的能力，材料的摩擦磨损主要是由对偶面上的微突起在样品表面的犁耕作用造成的。同时，水也起到了冷却剂的作用。     

碳纤维改性聚四氟乙烯的摩擦及振动性能

文中研究了20%的碳纤维(体积分数)改性聚四氟乙烯在干摩擦和水润滑摩擦条件下的摩擦系数、磨损性能和摩擦振动性能。结果表明:(1)在干摩擦下,随着线速度增加,摩擦界面生成大量的热,黏着磨损和磨粒磨损严重,表面越来越粗糙,摩擦系数明显变大,摩擦振动加速度增加。而在水润滑条件下,随着线速度增加,摩擦界面间形成了一层水润滑膜,使摩擦系数降低,另外由于转速增加,使流噪声增加,从而使振动增加。(2)在干摩擦下,随着比压增加,摩擦系数和摩擦振动变化较大,而在水润滑条件下,随着比压增加,摩擦系数和摩擦振动变化较小。(3)干摩擦时,碳纤维增强聚四氟乙烯复合材料在不同比压下的磨损机理主要是磨粒磨损和黏着磨损;水润滑条件下,碳纤维增强聚四氟乙烯复合材料在高比压下的磨损机理主要是黏着磨损。因此,碳纤维改性聚四氟乙烯复合材料应该在水润滑条件下应用有利于提高耐磨性,降低摩擦系数和摩擦振动。     

PTFE微粉/CF改性PEEK复合材料的摩擦磨损性能

为解决核电水循环系统中鼓型旋转滤网驱动装置的耐腐蚀问题,本文研究了碳纤维和聚四氟乙烯微粉改性的聚醚醚酮复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能.通过机械共混、高温模压的方法,制备了不同质量分数的聚四氟乙烯(PTFE)微粉/碳纤维(CF)/二硫化钼(MoS_2)/聚醚醚酮(PEEK)复合材料.采用拉伸试验机和塑料洛氏硬度计测试其力学性能,采用摩擦磨损试验机测试了复合材料在干摩擦、水润滑和油润滑条件下的摩擦磨损性能,采用扫描电子显微镜对其摩擦表面形貌进行分析.结果表明:复合材料在水润滑和油润滑时摩擦系数及磨痕宽度均较小,但水润滑时摩擦系数波动幅度较大且磨痕宽度略高;复合材料在干摩擦条件下的磨损机制以磨粒磨损为主,伴有疲劳磨损,油润滑时摩擦面可形成连续的润滑膜而保持光滑,水润滑时水流冲刷破坏了摩擦面上固体润滑膜的稳定性;CF质量分数增加时,复合材料的洛氏硬度和压缩强度递增,压缩强度达到164 MPa,PTFE微粉质量分数增加时,复合材料的洛氏硬度和压缩强度递减;CF质量分数增加时,复合材料的干摩擦系数及磨痕宽度下降,PTFE微粉质量分数增加时,复合材料的干摩擦系数下降,达到0.17.     

碳化硅/碳化钨硬面密封摩擦副的摩擦磨损性能和机理研究

实验研究了干摩擦和水润滑条件下, 常压固相烧结碳化硅陶瓷(SSiC)及常压液相烧结碳化硅陶瓷(LPSiC)分别与碳化钨(WC)组成的硬面配对摩擦副的滑动摩擦磨损性能。在干摩擦条件下, 与LPSiC/WC摩擦副相比, SSiC陶瓷由于具有更大的晶粒尺寸和硬度, 导致SSiC/WC摩擦副具有更大的摩擦系数和更小的磨损量。磨损区域的SEM形貌结合面扫描分析、微区XRD分析结果表明: 微犁沟和微断裂导致SiC陶瓷的磨损, 疲劳损伤导致WC材料的磨损, 而摩擦过程产生的摩擦热导致磨出的WC颗粒氧化成无定型WO₃。在水润滑条件下, 与SSiC/WC摩擦副相比, LPSiC/WC摩擦副具有更大的摩擦系数和更低的磨损率。在干摩擦和水润滑条件下, 与SiC陶瓷作为动摩擦副配对相比, SiC陶瓷作为固定摩擦副的摩擦配对具有更小的摩擦系数和质量损失。     

纤维增强尼龙复合材料的摩擦磨损性能研究

分别研究了不同条件下连续C纤维和三维编织纤维增强铸型尼龙复合材料的摩擦磨损性能,并对磨痕和磨屑表面形貌进行了观察和分析.结果表明:干摩擦条件下三维编织C纤维增强铸型尼龙(简称C3D/MCPA)复合材料的磨损率明显低于连续C纤维增强铸型尼龙(简称CL/MCPA)复合材料;水润滑条件下C3D/MCPA复合材料的摩擦系数和磨损率几乎为干摩擦时的50%.三维编织C纤维/芳纶纤维混杂增强铸型尼龙(简称HF/MCPA)复合材料中随C纤维相对体积比的提高,磨损率下降而摩擦系数变化不大.     

聚四氟乙烯/碳纤维增强聚酰亚胺复合体系的摩擦学性能

研究评价了不同PTFE含量的碳纤维增强P1复合材料的力学和摩擦学性能，并分析了在干摩擦和水润滑2种不同条件下的磨损表面形貌和磨损机理。研究表明：PTFE以10%添加时PI/CF/PTFE体系的机械性能最佳，而摩擦学性能以5%添加为佳；随PTFE含量的增加，复合材料的摩擦系数降低，磨损率增加。水润滑下，摩擦系数和磨损率比干摩擦下的都有相应的降低。干摩擦下，材料的磨损均以塑性变形、微观破裂及破碎为主导；水润滑下，这一机制显著减弱，归因于水的润滑和冷却作用。     

三维编织复合材料在润滑条件下的摩擦性能

利用树脂传递模塑(RTM)工艺制备了三维编织炭纤维/环氧(C3D/EP)复合材料.采用MM-200型摩擦磨损试验机研究了该材料润滑条件下的摩擦磨损性能,探讨了载荷及滑动速度等外界因素的影响;并采用XL30 ESEM电子显微镜观察磨损表面形貌,分析了其磨损机理.结果表明,润滑条件下复合材料的摩擦磨损性能远优于干摩擦,且磨合期较短;随着载荷的增加,复合材料的摩擦系数和比磨损率降低,但滑动速度对摩擦磨损性能的影响很小;润滑条件下的磨损机理主要是磨粒磨损.     

铸型尼龙及其复合材料的摩擦学性能和晶型转变

利用 MM- 2 0 0摩擦磨损试验机研究了在干摩擦和水润滑条件下铸型尼龙 (MC尼龙 )及其复合材料的摩擦磨损性能 ,并利用红外光谱分析了材料在不同磨损条件下发生的物理化学变化。研究结果表明 ,在干摩擦条件下 ,当载荷与速度的积 (pv值 )小于 84 N.m/s时玻璃纤维增强 MC尼龙复合材料(GF/MC)的摩擦系数和磨损率都比 MC尼龙低 ;当 pv值大于 84 N.m/s时 ,GF/MC的摩擦系数略高于MC尼龙 ,而磨损率则远大于 MC尼龙 ,随 pv值的改变 ,磨损机理发生了变化。在水润滑条件下二者的摩擦系数降低 ,GF/MC的耐磨性比纯基体显著提高。光谱分析表明 ,MC尼龙及其复合材料在摩擦过程中会发生晶型转变 ,在干摩擦后 α晶型减少 ,γ晶型增多 ,在水润滑后 α晶型增多 ,而 γ晶型减少     

不同转速及载荷下炭/炭复合材料的摩擦磨损性能

在MM-200型摩擦磨损试验机上,对3K炭布叠层结构的炭/炭(C/C)复合材料进行低能条件下的摩擦磨损实验,用扫描电子显微镜对其磨损表面形貌进行观察分析.结果表明:在于摩擦条件下,随转速增加,复合材料的摩擦系数降低,磨损量增大.随载荷增加,复合材料的摩擦系数降低,磨损量增大.摩擦初始时主要磨损机理为磨粒磨损和粘着磨损,润滑膜产生后主要磨损机理为疲劳磨损.炭/炭复合材料在低能条件下的磨损是正常磨损,其摩擦系数在0.1～0.2,温度在0～100℃之间.     

针刺毡C/C复合材料磨擦制动压力和速度特性

用模拟刹车制动的摩擦试验机,研究探讨了一种针刺毡结构C/C复合材料在不同制动压力和制动速度下的摩擦磨损性能,并用扫描电子显微镜对摩擦表面进行了观察和分析。摩擦磨损机理由磨屑经挤压、剪切堆积在表面形成的磨屑层所决定。在5m/s制动速度或静态条件下,表面温度低(<150~200℃)吸附水气未脱附,其润滑作用导致了较低的摩擦系数值;当制动速度达到10m/s,摩擦使表面温度升高,达到了吸附水气脱附温度,引起摩擦系数急剧升高,达到了最大;此后,随制动速度及表面温度的继续升高,磨屑层间剪切强度降低,导致摩擦系数随之下降。在较高制动速度下,该种材料仍能保持较高的摩擦系数,显示出优良的高温高能摩擦性能。     

Friction and wear behavior of carbon nanotubes reinforced polyamide 6 composites under dry sliding and water lubricated condition

The friction and wear behavior of carbon nanotube reinforced polyamide 6 (PA6/CNT) composites under dry sliding and water lubricated condition was comparatively investigated using a pin-on-disc wear tester at different normal loads. The morphologies of the worn surfaces and counterfaces of the composites were also observed with scanning electron microscopy (SEM). The results showed that CNTs could improve the wear resistance and reduce the friction coefficient of PA6 considerably under both sliding conditions, due to the effective reinforcing and self-lubricating effects of CNTs on the PA6 matrix. The composites exhibited lower friction coefficient and higher wear rate under water lubricated condition than under dry sliding. Although the cooling and boundary lubrication effect of the water contributed to reduce the friction coefficient of the composites, the adsorbed water lowered the strength of the composites and also inhibited the formation of transfer layers on the counterfaces resulting in less wear resistance. With the increasing normal loads, the friction coefficient of the composites increased under the dry sliding and decreased under the water lubricated condition, owing to inconsistent influences of shear strength and real contact areas. The specific wear rate of the composites increased under both sliding conditions.     

Sliding friction and wear behaviour of vinylester and its composites under dry and water lubricated sliding conditions

In this paper, we studied and explored the tribological performance of pure vinylester (V), glass fiber reinforced (GFR), SiC filled glass fiber reinforced vinylester composite under dry and water lubricated sliding conditions. Friction and wear tests were carried out with configuration of a pin on a rotating disc under ambient conditions. Tests were conducted at normal load 10, 30 and 50 N and under sliding speed of 1.6 m/s, 2.8 m/s and 4 m/s. The results showed that the coefficient of friction decreases with the increase in applied normal load values both under dry and water lubricated conditions. On the other hand for pure vinylester specific wear rate increases with increase in applied normal load under dry sliding condition and decreases with increase in applied normal load under water lubricated conditions. However the specific wear rate for GFR vinylester composite and SiC filled GFR vinylester composite decreases with the increase in applied normal load both under dry and water lubricated conditions. Moreover, for the range of load and speeds used in this investigation the coefficient of friction and specific wear rates using water lubricant registered lower values than that of the dry condition. The specific wear rates for pure vinylester and vinylester + 50 wt.% GFR and SiC filled GFR vinylester composite under dry and water lubricated sliding condition were in the order of 10⁻⁷ mm³ N⁻¹ mm⁻¹.     

镍基复合材料在水环境中的摩擦学性能及磨损机理研究

本文考察了Ni-SiC-石墨系复合材料在水环境中的摩擦学性能,并研究其磨损机理.结果表明:复合材料在水环境中的摩擦系数比干摩擦降低了一半左右,磨损率仅为干摩擦下的1/15,水环境中,负荷和速度的变化对摩擦系数的影响不大,摩擦系数基本保持在0.28～0.32之间,磨损率随负荷和滑动速度的增加而不断增加.磨损表现为机械微切削;摩擦副表面吸附水的边界润滑作用以及水的冷却作用使材料容易耗散摩擦热,塑性变形减小,严重粘着磨损明显减轻.水的存在使不锈钢偶件更容易发生氧化,同时暴露于磨损表面的SiC以及由于水的渗透而导致与基体脱粘的SiC,易被氧化生成SiO2,进而SiO2发生水合反应在磨擦对偶表面生成不均匀的SiO2·nH2O水合反应膜,起到了一定的减磨润滑作用,显著降低摩擦系数和磨损率.     

AlNP/Al和TiB2P/Al复合材料摩擦磨损性能研究

研究了油润滑条件下两种不同铝基复合材料及其基体合金的摩擦磨损性能,分析了增强体对材料摩擦磨损性能的影响以及相应的磨损机理.结果表明:油润滑条件下,随着摩擦时间的延长,AlNP/Al复合材料的摩擦系数由小变大趋于稳定;而TiB2P/LY12复合材料的摩擦系数却是由大变小趋于稳定,这主要与其摩擦过程中形成凹坑产生润滑油膜有关.由于增强体强度的增加,50%(体积分数,下同)TiB2P/Al复合材料的摩擦系数低于50%AlNP/Al复合材料,且耐磨性优于50%AlNP/LY12复合材料.增强相的加入显著提高了材料的耐磨性,使得复合材料的抗粘着能力明显优于基体合金.     

Tribological behavior of aluminum-CNT coated metal composite under dry and water lubricated conditions

Carbon nanotubes are considered the best material in the field of composites because of their mechanical and tribological properties. In this study, carbon nanotubes coated metal was dispersed in aluminum, the base metal, to improve the wettability between aluminum and carbon nanotubes. The friction and wear behaviors of the aluminum-carbon nanotube coated metal, which is a nickel and copper composite, were investigated using a pin-on-disk wear tester under dry sliding and water lubricated conditions and evaluated using SEM and EDX analysis. All the results demonstrated that the addition of the carbon nanotubes coated metal significantly improved the wettability of CNTs in the aluminum. And the distribution of CNTs prevented the propagation of micro cracks on the surface of the aluminum base metal sample, resulting in enhanced friction characteristics and wear resistance of the nano composite. The composite exhibited lower friction coefficient and wear resistance under the water lubricated condition than the dry sliding condition. Although the lubrication and cooling effect of water contributed to the reduction of the friction coefficient of the composite, the separation of wear particles from the sliding surface changed the wear type from three-body to two-body, resulting in very high wear rate. Also the concentration of oxide under water lubricated condition contributed to the increase of the wear rate because the amount of oxide film removed in terms of thickness exceeded the critical thickness of real contact area.     

热处理对Al2O3f+Cf/ZL109混杂复合材料干滑动摩擦磨损性能影响的统计学研究

利用挤压铸造法制备了Al₂O_3f+C_f/ZL109短纤维混杂增强金属基复合材料,并利用统计学方法对比研究了在滑动速度为0.837 m/s、压力为196 N的条件下热处理对该混杂复合材料干摩擦磨损性能的影响。研究结果表明:铸态和热处理态复合材料的磨损率和摩擦系数均服从正态分布,铸态复合材料的磨损率和摩擦系数均值都大于热处理态复合材料,热处理有利于复合材料摩擦磨损性能的提高。铸态复合材料的磨损机制主要为犁沟磨损和层离,热处理后复合材料抗层离的能力增强,磨损机制主要为轻微的犁沟磨损。     

Role of micro/nano fillers on mechanical and tribological properties of polyamide66/polypropylene composites

The objectives of this research article is to evaluate the mechanical and tribological properties of polyamide66/polypropylene (PA66/PP) blend, graphite (Gr) filled PA66/PP, nanoclay (NC) filled PA66/PP and NC plus short carbon fiber (NC + SCF) filled PA66/PP composites. All composites were fabricated using a twin screw extruder followed by injection molding. The mechanical properties such as tensile, flexure, and impact strengths were investigated in accordance with ASTM standards. The friction and sliding wear behaviour was studied under dry sliding conditions against hard steel on a pin-on-disc apparatus. Scanning electron micrographs were used to analyze the fracture morphologies. From the experimental investigation, it was found that the presence of NC and SCF fillers improved the hardness of PA66/PP blend. Further, the study reveals that the tensile and flexural strength of NC + SCF filled PA66/PP was higher than that of PA66/PP blend. Inclusion of micro and nanofillers reduced the wear rate of PA66/PP blend. The wear loss of the composites increased with increasing sliding velocity. The lowest wear rate was observed for the blend with nanoclay and SCF fillers. The wear rates of the blends with micro/nanofillers vary from 30–81% and lower than that of PA66/PP blend. The wear resistance of the PA66/PP composites was found to be related to the stability of the transfer film on the counterface. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.     

Friction and Wear Behavior of Resin/Graphite Composite under Dry Sliding

The friction and wear behavior of resin/graphite composite has been investigated using a pin-on-disc configuration under dry sliding condition. The results showed that the resin/graphite composite exhibited much better mechanical and tribological properties compared with the unimpregnated graphite. The friction coefficient was reduced by addition of furan resin, which could also prevent the"dusting" wear at loads more than 15 MPa. The steady and lubricated transfer film was easily formed on the counterpart surface due to the interaction of furan resin and wear debris of graphite, which was useful to reduce the wear rate of the resin/graphite composite. The composite is highly promising for mechanical sealing application and can be used at high load for long time sliding.     

Design of newly fabricated tribological machine for wear and frictional experiments under dry/wet condition

Nowadays, there is demand to evaluate tribological performance of new engineering materials using different techniques. Various laboratory tribo-machines have been designed and fabricated such as Pin-on-Disc (POD), ASTM G99, Block-on-Ring (BOR), ASTM G77 or G137-953, Dry Sand Rubber Wheel (DSRW), ASTM G655, Wet Sand Rubber Wheel (WSRW), ASTM G105, and sand/steel wheel test under wet/dry conditions (ASTM B611). A concept of integrating more than one tribo-technique at different contact mechanisms (line or area) working simultaneously under same test condition against same material is introduced in a current designed machine. Different wear modes (adhesive, two-body-abrasive, three-body-abrasive, under dry, lubricated, or slurry conditions) can be conducted on the same machine. Results of adhesive wear, friction and interface temperature of glass fibre reinforced polyester composite under wet/dry contact condition are reported at 50 N load for different sliding speeds (2.8–7.8 m/s) using the new machine. Weight loss and friction coefficient of the composite were substantially influenced by introducing water as lubricant. Additionally, the contact condition has the high influence key on the wear and frictional performance of the composite.