CPR/NR和高性能填料对复合摩擦材料力学性能的影响

通过干法热压成型工艺制备性能优异的复合摩擦材料,研究了高性能填料以及改性酚醛树脂与丁腈橡胶质量比(CPR/NR)对复合摩擦材料性能的影响规律。对材料的摩擦磨损性能与力学性能进行了测试,借助热分析仪测试其耐热性能,并利用激光共聚焦显微镜、扫描电镜对表面形貌进行了观察和分析。结果表明,复合摩擦材料的密度、压缩强度、压缩模量、硬度随橡胶含量的减少而增加,冲击强度则呈相反的趋势。橡胶含量的减少,树脂比例的增加,使复合摩擦材料的耐热性得到提高,促进了第二接触面的形成,使摩擦系数与磨损率降低。高性能填料含量较低时,材料表面形成大且连续的第二接触面,第二接触面使摩擦系数、比磨损率降低,复合摩擦材料的主要磨损形式为粘着磨损与磨粒磨损;填料含量的增加会阻碍第二接触面的形成,使材料摩擦系数和比磨损率逐渐增大,材料的磨损形式由粘着磨损、磨粒磨损转变为磨粒磨损和疲劳磨损。     

国外C/C复合材料飞机刹车盘的摩擦表面特性和摩擦磨损机理

在MM-1000型摩擦试验机上,对英、法、美三国四大炭盘制造商的五种炭盘小样进行了摩擦磨损性能测试,对摩擦表面进行了宏观和扫描电子显微镜(SEM)微观形貌分析,对各试样的摩擦磨损过程和机理进行了一定的探讨.结果表明:石墨化度决定了膜的完整程度,且成正比关系,坯体结构对摩擦膜有一定的影响;纯树脂炭基体的试样表面膜厚度较小,完整致密性与热解炭基体的试样差别较大,磨损较大;C/C复合材料的机械磨损以粘着、犁沟、磨粒磨损为主,膜越完整的材料呈现出以粘着磨损为主,对于低石墨化度的和纯树脂炭基体的C/C复合材料表现出犁沟、磨粒磨损为主,粘着磨损为辅.     

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.     

La2O3填充超高分子量聚乙烯的摩擦磨损性能

用La2O3对超高分子量聚乙烯(UHMWPE)进行了填充改性，测试了La2O3填充量对其硬度及摩擦学性能的影响。用扫描电镜观察了材料摩擦表面磨痕形貌。结果发现：随着La2O3含量的增加，UHMWPE—La2O3复合材料的硬度上升。填充量为6％的UHMWPE—La2O3复合材料在干摩擦及磨粒磨损条件下的磨损率都最小。UHMWPE在干摩擦下的磨损主要表现为犁沟及粘着，填充La2O3可减轻磨损表面的犁沟，但填充量过高，磨损转变为表面脆性脱落。     

碳纤维/碳基摩擦材料的摩擦学性能研究

为适应坦克装甲车辆对摩擦系统高能量密度的要求,采用树脂浸渍碳化工艺制备了碳纤维/碳基摩擦材料,通过离合器试验台对材料进行了摩擦磨损试验,并使用扫描电子显微镜(SEM)、能谱分析仪(EDS)和3D激光形貌仪对材料表面形貌和磨屑形貌进行了分析。结果表明,碳纤维/碳基摩擦材料的动摩擦系数稳定(μ=0.11);摩擦扭矩曲线平滑,制动平稳性好;体积磨损率为3.2×10-8 mm3·J,耐磨性好;耐热系数达43 900J2·mm-4·s-1,可以在高能量密度工况下使用。碳纤维/碳基摩擦材料与钢对偶片之间的主要磨损机制为犁沟磨损和磨粒磨损。     

C/C及C/C-Cu复合材料的摩擦磨损性能

通过化学气相渗透(CVI)、树脂浸渍/碳化(I/C)的工艺制成多孔的C/C预制件,采用气体压力浸渗方法向预制体中渗入铜,制备出C/C-Cu复合材料。以高密度C/C复合材料(1.9g/cm~3)作为对比样,在MM-200型磨损试验机上对其摩擦磨损性能进行测试,并对其微观结构和摩擦磨损机理进行分析。研究结果表明:C/C-Cu的摩擦系数比C/C复合材料的低,这主要与摩擦表面的摩擦膜有关,铜在摩擦力带动下填充摩擦表面的凹坑,并与碳材料共同形成摩擦膜,摩擦膜的碳含量越高,润滑效果越好。当C/C预制件密度为1.59g/cm~3时,C/C-Cu的摩擦系数和磨损量均小于C/C复合材料,摩擦磨损性能良好。     

石墨/CNTs增强铝基混杂复合材料的微观组织与摩擦磨损性能

采用粉末冶金法制备了石墨/碳纳米管(CNTs)增强铝基复合材料,研究了石墨和碳纳米管对复合材料摩擦磨损性能及硬度的影响,并利用扫描电子显微镜观察了复合材料的显微组织、磨损表面形貌。结果表明:仅添加石墨的复合材料摩擦系数明显降低,而磨损率、硬度有少量降低;但是将石墨和碳纳米管混杂加入到复合材料中后,材料的摩擦系数明显降低,磨损率急剧升高,且材料的硬度随碳纳米管含量增加而逐渐下降。仅添加石墨的复合材料磨损形式主要是磨粒磨损和犁沟磨损,而添加石墨和碳纳米管的复合材料主要是剥层磨损。     

Ti_3SiC_2-Ag复合材料与不同摩擦配副的摩擦磨损性能

采用放电等离子烧结技术制备了Ti3Si C2-Ag复合材料,研究了其在室温下与Si3N4、Al2O3、Si C等摩擦配副对摩时的摩擦磨损性能,并与纯Ti3Si C2材料在相同摩擦配副条件下的摩擦磨损性能进行了对比。运用扫描电子显微镜、X射线光电子能谱仪等对磨损表面的形貌组织和元素价态等进行了表征分析,并探讨了摩擦磨损机理。结果表明:摩擦配副材料的不同对Ti3Si C2-Ag复合材料的摩擦磨损行为有显著影响,Ti3Si C2-Ag复合材料与Si C和Si3N4对摩时,磨损率均较低,尽管存在晶粒拔出等机械磨损,但Ti O2和Si Ox等摩擦氧化膜的形成有效地抑制了晶粒拔出并起到了减摩作用;Ti3Si C2-Ag复合材料与Al2O3对摩时磨损率则较高,以脆性断裂、晶粒拔出为主的机械磨损是该摩擦副的主要磨损机制。Ti3Si C2材料与Si3N4和Al2O3对摩时,包含脆性断裂、晶粒拔出、脱落以及磨粒磨损在内的机械磨损是其主要的磨损机制;Ti3Si C2材料与Si C对摩时,磨损表面的塑性变形和氧化膜起到了抑制晶粒拔出的作用,使得Ti3Si C2的磨损率相对较低。     

超细γ-Al2O3/铜纤维对树脂基摩擦材料摩擦性能的影响

采用热压成型法制备了超细γ-Al2O3/铜纤维增强树脂基摩擦材料,运用模糊分析法考察γ-Al2O3含量对半金属摩擦材料摩擦磨损性能的影响.实验结果表明,γ-Al2O3/铜纤维增强树脂基摩擦材料具备适中的摩擦系数、良好的热稳定性能;随γ-Al2O3含量的增加,材料的摩擦稳定系数增大.SEM分析表明,当γ-Al2O3含量为3%时,复合材料的综合磨损率最小,磨损形式以粘着磨损为主;随γ-Al2O3含量的增加,综合磨损率逐渐增大,磨损形式为粘着磨损和磨粒磨损的复合磨损形式.     

碳/碳-碳化硅复合材料的摩擦磨损行为与机理

以液相渗硅工艺为手段制备了C/C-SiC复合材料。分别采用MMW-1A与MM-1000型试验机对复合材料的摩擦磨损性能进行了研究。结果表明: 在实验室条件下, 当压力恒定在0.48 MPa时, 转速对复合材料的摩擦磨损的性能影响甚微, 摩擦系数为0.15~0.16, 且磨损率接近; 当转速恒定在0.3 m/s时, 不同压力条件下的摩擦系数相近, 为0.13~0.15, 但磨损率存在较大差异, 材料磨损以磨粒磨损为主。在近工况条件下, C/C-SiC复合材料的摩擦系数达到0.50, 磨损率达到5.95 mg/次, 摩擦曲线表现为典型的马鞍形曲线, 试验前期材料磨损主要表现为磨粒磨损, 试验后期为粘着磨损。     

改性酚醛树脂陶瓷摩擦材料的摩擦磨损性能

以普通酚醛树脂、硼改性酚醛树脂、三聚氰胺改性酚醛树脂为黏结剂,以陶瓷纤维为增强纤维,制备了3种酚醛树脂陶瓷摩擦材料。对其冲击韧性和硬度进行实验测试,采用摩擦磨损试验机考察其摩擦磨损性能,采用扫描电子显微镜(SEM)和X射线能谱仪分析其磨损表面形貌及其成分,并探讨其磨损机制。结果表明:硼改性酚醛树脂黏结剂能够提高摩擦材料的硬度,三聚氰胺改性酚醛树脂黏结剂能够提高摩擦材料的冲击韧性,降低摩擦材料硬度;在摩擦过程中三聚氰胺改性酚醛树脂在高温下炭化,在摩擦材料表面形成一层致密的摩擦层,摩擦层的存在使摩擦材料的摩擦因数相对比较稳定,降低了摩擦材料的磨损率。     

碳纳米管掺杂Fe3Al基复合摩阻材料的摩擦磨损特性研究

采用冷压烧结法制备了CNTs-Fe3Al基复合摩阻材料。经添加0.5%~5%CNTs、1%~5%Al2O3,研究了掺杂物含量及摩擦载荷对摩阻材料摩擦磨损性能的影响,并采用SEM对材料初始表面形貌及磨损形貌进行了观测。结果表明,随着CNTs及Al2O3含量的逐渐增加,磨损方式将由磨粒磨损向疲劳磨损转变。添加CNTs时,摩擦系数先降低后升高再降低;添加Al2O3时,摩擦系数不断升高。加入0.5%CNTs、3%Al2O3可制备平均摩擦系数0.7,硬度295.8HV的摩阻材料。     

Friction and wear behavior of three-dimensional braided carbon fiber/epoxy composites under lubricated sliding conditions

The friction and wear characteristics of three-dimensional (3D) braided carbon fiber-epoxy (C_3D/EP) composites under lubricated sliding conditions against a quenched medium-carbon steel counterface were studied. Wear tests were performed under different loads at two velocities. Comparative wear tests under dry conditions were carried out to investigate the influence of lubrication. Tribological properties of the C_3D/EP composites with various fiber loadings and two different fiber-matrix adhesion strengths were assessed. It was found that the lubricated contact promoted lower wear rates and friction coefficients. Compared to dry sliding, the tribological performance of the C_3D/EP composites under lubrication was less dependent on fiber content, fiber-matrix bonding, load, and velocity than dry sliding. The worn surfaces of the C_3D/EP composites were analyzed by scanning electron microscopy (SEM) to explore the relevant mechanisms.     

新型填料对高摩复合材料摩擦磨损性能影响及机制

采用干法热压成型工艺制备高摩复合材料,研究了基体材料腰果壳油改性酚醛树脂(CPR)与丁晴橡胶(NR)的质量比和新型高性能填料(主要成分为石墨粉Al2O3、MoS2、Fe粉)含量对高摩复合材料摩擦磨损性能的影响规律。在摩擦磨损试验机上测试了高摩复合材料的摩擦磨损性能,利用激光共聚焦显微镜、扫描电镜对摩擦表面形貌、磨屑进行观察和分析,借助EDS测定摩擦表面成分的变化。结果表明,随着CPR与NR质量比的增加,高摩复合材料的耐热性能、结合性能大幅提高,且具有较好的摩擦磨损性能。当高性能填料含量较低时,磨损表面出现大量连续的真实接触面,磨损机制为磨粒磨损和黏着磨损;当高性能填料含量较高时,真实接触面积减少,磨损表面剥落严重,并出现较多的裂纹,其主要磨损形式转变为磨粒磨损和疲劳磨损。随着高性能填料含量的增加,摩擦表面的元素从均匀分布逐渐转变为局部富集,磨粒的尺寸逐渐变大。     

Effects of Mixing the Steel and Carbon Fibers on the Friction and Wear Properties of a PMC Friction Material

Friction, fade and wear characteristics of a PMC friction material containing phenolic resin, short carbon fiber, graphite, quartz, barite and steel fiber were investigated through using a small-scale friction testing machine. Four different friction materials with different relative amounts of the carbon fiber and steel fiber were manufactured and tested. Comparing with our previous work which contained only steel fiber as reinforcement, friction characteristics such as fade and recovery and wear resistance were improved significantly by adding a small amount of carbon fiber. For the mixing of carbon and steel fiber, the best frictional and wear behavior was observed with sample containing 4 weight percentage carbon fiber. Worn surface of this specimen was observed by optical microscopy. Results showed that carbon fibers played a significant role in the formation of friction film, which was closely related to the friction performance. The brake pad with Steel fibers in our previous work, showed low friction coefficient and high wear rate. In addition, a friction film was formed on the surface with a relatively poor quality. In contrast, the samples with mixing the steel and carbon fiber generated a stable friction film on the pad surface, which provided excellent friction stability with less wear.     

Sliding friction and wear behavior of Fe-based bulk metallic glass in 3.5% NaCl solution

The corrosion wear behaviors of a Fe-based bulk metallic glass Fe_66.7C_7.0Si_3.3B_5.5P_8.7Cr_2.3Al_2.0Mo_4.5 against Si₃N₄ ceramic ball was studied in a 3.5% NaCl solution and using a unidirectional tribometer with the ball-on-disk configuration. During friction process, the Fe-based BMG showed tribochemical reaction with the 3.5% NaCl solution. Wear occurred mainly through an abrasive wear mechanism and corrosive wear effects. The overall average friction coefficient was in the range of 0.18 to 0.25 according to the test conditions and slightly decreased with increasing load. The wear resistance of the BMG was better than that of the conventional bearing steel, demonstrating the potential of the BMG as a viable engineering alloy for anti-corrosive wear applications.     

树脂粘结剂对汽车摩擦材料性能的影响

制备了不同树脂基体和不同树脂含量的汽车摩擦材料,研究了树脂种类与含量对汽车摩擦材料的机械性能和摩擦磨损性能的影响。结果表明,腰果壳油改性酚醛树脂为基体的摩擦材料的摩擦、耐热和力学性能,均优于纯酚醛树脂基摩擦材料。树脂-丁腈橡胶共混改性摩擦材料具有更好的力学性能和耐磨性,摩擦系数稳定。随着树脂粘结剂含量的增加,摩擦材料的力学性能提高。树脂粘结剂的含量在9%~12%时,摩擦材料具有优异的摩擦磨损性能;树脂粘结剂的含量小于6%时,摩擦系数较低且不稳定;树脂粘结剂的含量大于15%时,材料发生热衰退现象。      

Friction and wear behavior of carbon fiber reinforced brake materials

A new composite brake material was fabricated with metallic powders, barium sulphate and modified phenolic resin as the matrix and carbon fiber as the reinforced material. The friction, wear and fade characteristics of this composite were determined using a D-MS friction material testing machine. The surface structure of carbon fiber reinforced friction materials was analyzed by scanning electronic microscopy (SEM). Glass fiberreinforced and asbestos fiber-reinforced composites with the same matrix were also fabricated for comparison. The carbon fiber-reinforced friction materials (CFRFM) shows lower wear rate than those of glass fiber- and asbestos fiber-reinforced composites in the temperature range of 100°C-300°C. It is interesting that the frictional coefficient of the carbon fiber-reinforced friction materials increases as frictional temperature increases from 100°C to 300°C, while the frictional coefficients of the other two composites decrease during the increasing temperatures. Based on the SEM observation, the wear mechanism of CFRFM at low temperatures included fiber thinning and pull-out. At high temperature, the phenolic matrix was degraded and more pull-out enhanced fiber was demonstrated. The properties of carbon fiber may be the main reason that the CFRFM possess excellent tribological performances.     

Si3N4和52100钢对磨副材料对CrN薄膜干摩擦学行为的影响

利用阴极电弧离子镀技术在316L不锈钢基体上制备了CrN薄膜。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪对CrN薄膜的形貌、成分和力学性能进行了表征。为了研究Si_3N_4和52100钢对磨副材料对CrN薄膜和316L不锈钢干摩擦行为的影响,在2N、5N、8N三种载荷下,将CrN薄膜和316L不锈钢基体与Si_3N_4陶瓷球和52100钢球分别进行了往复式滑动干摩擦实验。采用扫描电子显微镜观察了磨痕的微观形貌,并对CrN薄膜和316L不锈钢基体的磨损机制进行了分析。结果表明:CrN薄膜表面平整,缺陷较少;CrN薄膜的纳米硬度约为28GPa,弹性模量约为350GPa;与Si_3N_4陶瓷球相比,CrN薄膜与52100钢球摩擦时摩擦因数相对较小(保持在0.7左右)且更加稳定;316L不锈钢的摩擦因数远大于CrN薄膜且波动较大;对磨球为Si_3N_4陶瓷球时,CrN薄膜的主要磨损机制为磨粒磨损,伴有少量的氧化和黏着磨损,316L不锈钢的磨损机制主要为磨粒磨损和塑性变形,伴有少量的氧化和黏着磨损;对磨球为52100钢球时,CrN薄膜的主要磨损机制为黏着磨损,伴有少量的氧化,316L不锈钢的磨损机制主要为黏着磨损,伴有少量的氧化和磨粒磨损。CrN薄膜与两种对磨球的磨损量均小于316L不锈钢基体的磨损量,说明CrN薄膜有效提高了基体的耐磨性。