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The Role of Transfer Layers on Friction Characteristics in the Sliding Interface between Friction Materials against Gray Iron Brake Disks 总被引:3,自引:0,他引:3
The effect of transfer layer formation on friction performance was studied using a brake friction material containing 15 ingredients.
Based on a base formulation, 13 friction material specimens containing different relative amounts of ingredients were produced
and they were tested on gray iron disks using a small-scale friction tester. A non-destructive four-point probe technique
to measure electrical resistance of the thin film was used to estimate the transfer layer thickness. Results showed that the
transfer layer formation was highly dependent on the relative amount of ingredients in the friction material and temperature.
Among various ingredients, solid lubricants and iron powders increased the transfer layer thickness but no apparent correlation
between transfer layer thickness and the coefficient of friction was found. Strong influence from individual ingredients was
observed, dominating the friction characteristics during sliding. On the other hand, the thick transfer layers on the disk
surface tended to reduce the friction material wear and the amplitude of the friction coefficient oscillation during sliding. 相似文献
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Carbon-rich fly ash has been reported to be a suitable precursor and catalyst for carbon nanotube (CNT) growth. In this work, CNTs grown from carbon-rich fly ash were evaluated as a lubricant oil additive to reduce the friction coefficient of metallic surfaces using a ball-on-disk tribometer. Different concentrations of the as-grown CNTs in the range 0.005–0.5 wt% were dispersed in a base sunflower oil. The value of the friction coefficient was also investigated as a function of load. Excellent results were obtained for the value of the friction coefficient, where it drastically decreased to around 58% of its original value without additives. This was achieved at a very low concentration of CNTs; that is, 0.1 wt%. The obtained result was compared with that of a commercial multiwalled CNT at the same concentration and found to be superior. This superiority of CNTs produced from fly ash could be attributed to the existence of active radical sites on their side wall. Moreover, the friction coefficient value was observed to decrease with increasing load, which might be due to the formation of protective graphitic carbon layers on antagonist surfaces. The viscosity of pure and 0.1 wt% CNTs-impregnated base oil was also studied in the 25–100°C temperature range. No significant changes are observed in the viscosity of the CNTs-impregnated base oil. These results suggest that the low-cost CNTs produced from fly ash are excellent nanomaterials as additives for lubricant oil. 相似文献
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四种车辆制动闸瓦材料摩擦特性试验研究 总被引:3,自引:2,他引:1
使用MM-1000型摩擦试验机,在不同的压力和速度下作了4种铁路车辆制动闸瓦材料与车轮钢的摩擦试验,测试它们的制动摩擦特性。试验结果表明,闸瓦材质对制动摩擦性能有较大的影响。高磷铸铁A、B两种材料的摩擦因数比较不稳定,在制动过程中摩擦因数出现了较大的波动,而且易受制动压力和速度的影响。高分子树脂复合材料C的摩擦因数比较稳定,受制动速度的影响较小但是受压力的影响较大。高分子树脂复合材料D的摩擦因数受制动速度的影响较大,但是受制动压力的影响则较小。 相似文献
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Effects of Resin Type and Fiber Length on the Mechanical and Tribological Properties of Brake Friction Materials 总被引:2,自引:0,他引:2
In this study, the effects of resin type and fiber length on mechanical properties and friction characteristics of automotive
brake materials were studied. Three types of resin, viz. straight phenolic resin (SR), cashew nut shell liquid modified resin
(CR), and melamine resin (MR) were used as matrix material. Lapinus with different lengths was used as inorganic fiber. Three
series of friction composites composed of nine composites in the form of brake materials were manufactured. Physical, mechanical,
and tribological properties of all composites were investigated. The friction tests were performed using a Chase type friction
tester. The results showed that both resin type and fiber length played an important role on the mechanical and tribological
properties of the friction materials. The highest and the lowest friction coefficient for resin types were recorded for SR
and MR composites, respectively, while MR and CR composites showed the highest and the lowest wear resistance, respectively.
For the fiber length considered, increasing the fiber length increased the wear resistance of the composites. The coefficient
of friction, in general, showed a good correlation with the wear resistance of the composites. But, there was no clear correlation
with the mechanical and tribological properties of the composites. The morphological features of worn surfaces and wear debris
of the composites were analyzed in order to understand the friction and wear mechanisms of this tribosystem. 相似文献
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粉煤灰空心微珠具有空心圆球结构,将其用于充填树脂基复合材料,可减少树脂用量、提升复合材料性能,同时促进粉煤灰排放废弃物的高附加值利用。采用不同粒径的粉煤灰空心微珠充填树脂基复合材料,研究不同粒径的粉煤灰空心微珠对复合材料密度、力学性能和摩擦磨损性能的影响。结果表明:随着粉煤灰空心微珠粒径的减小,复合材料的密度呈先降低后增加的趋势,硬度和冲击强度呈先增加后减少的趋势;粉煤灰空心微珠粒径为120~140目时,复合材料密度最小,粒径小的空心微珠更有利于降低复合材料的密度;粒径为80~100目时,复合材料冲击强度最大;采用较大粒径粉煤灰空心微珠充填树脂基复合材料,更有利于提高复合材料的高温摩擦因数,改善树脂基复合材料的抗热衰退性能;粒径20~40目和60~80目粉煤灰空心微珠复合材料具有良好的综合摩擦磨损性能。 相似文献
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现代制动用刹车材料的应用研究和展望 总被引:1,自引:0,他引:1
阐述了现代制动用刹车材料的应用研究现状,分析了现代制动用刹车材料研究和应用中存在的问题,提出了现代制动用刹车材料的研究和应用方向。 相似文献
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Tribological Characteristics of Binder Resins for Brake Friction Materials at Elevated Temperatures 总被引:1,自引:0,他引:1
The heat resistance of the multiphase friction materials made with straight phenolic resin (ST), boron–phosphorous (B–P)-modified phenolic resin (BP), or polyimide (PI) was investigated using a Krauss-type friction tester. Thermal analysis of the cured resins was also carried out to examine the chemical and mechanical properties of the resin and their effects on the wear rate and the coefficient of friction. The results showed that the fade and wear of the friction materials were closely related to the thermal decomposition of the binder resin and durability of the contact plateaus, which were produced by the compaction of wear debris around hard ingredients on the rubbing surface. The friction material containing the B–P modified resin was more resistant to wear and fade than the other binder resins. On the other hand, the friction material with polyimide showed good fade resistance but exhibited excessive wear despite its good thermal resistance. 相似文献
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ABSTRACTIn this article, brake discs are exposed to high thermal stress, causing thermal fatigue damage. The aim of this work is to study the evolution of the wear behavior of brake disc materials, such as cast iron, chromium steel, and metal matrix composites, under the influence of thermal fatigue. The brake disc specimens are heated and then cooled rapidly. Then, wear tests are carried out using a pin-on-disc-type tribometer. Organic and semimetallic friction materials are used for all wear tests. The results show that thermal fatigue affects the structure of the contact surfaces of all of the disc specimens by increasing their roughness. Furthermore, the wear rate of the friction materials increased, except a reduction of the wear rate is noted for the semimetallic friction material rubbing against cast iron. Moreover, thermal fatigue has no significant influence on the coefficient of friction. The worn surface of the metal matrix composite sliding against semimetallic friction material is characterized by abrasive and adhesive wear mechanisms. 相似文献
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硼酸酯与聚醚复配水溶液的摩擦学性能研究 总被引:2,自引:0,他引:2
水的润滑性能较差,因此需要选取性能良好的水溶性添加剂对其摩擦性能进行改善。研究选取椰油酰胺聚氧乙烯醚(CPOE)和三乙醇胺硼酸酯(BN)作为添加剂,分别对CPOE和CPOE-BN水溶液的摩擦学性能进行研究。使用NGY-6纳米级膜厚测量仪测试两种溶液的成膜性能,结果表明两种溶液在低浓度下均具有良好的成膜能力。利用四球试验机对两种溶液的减摩抗磨性能、稳定性能和极压性能进行了研究,结果表明两种溶液在低浓度下均具有良好且稳定的减摩抗磨性能,BN的加入可以大大提高CPOE水溶液的减摩性能和高载荷下的抗磨性能。利用XPS技术对CPOE-BN磨痕表面的化学元素进行了分析,结果表明在磨痕的表面生成了氮化硼、硼化铁等化合物,起到了良好的减摩抗磨效果。研究表明,CPOE和BN具有良好的协同润滑效果,是一种具有良好工业应用前景的绿色水基润滑添加剂。 相似文献
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The tribological characteristics of brake friction materials containing different shapes of potassium titanate were investigated.
They contain typical ingredients of a non-asbestos organic based friction material, including potassium titanate in the shapes
of whiskers, platelets, and splinters. A Krauss type friction tester is used to obtain thermal stability and wear resistance
of the friction materials at elevated temperatures. The results showed that the morphology of potassium titanate plays an
important role in the formation of contact plateaus and transfer films on the rubbing surfaces, which are closely associated
with tribological properties. The friction material with splinter shape potassium titanate shows better friction stability
and improved wear resistance compared to those containing other types of potassium titanate due to larger contact plateaus
and stable friction films at the sliding interface. On the other hand, the transfer films produced by the friction materials
with platelet or whisker potassium titanate are not sustainable at elevated temperatures since they are easily detached during
sliding, resulting in poor wear resistance. 相似文献
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In this work the semi-metallic friction composites with moderately increased content of Al2O3 (0, 3.4, 5.6, 9.0, and 14.6 vol%) were successfully fabricated by casting technology and their tribological properties were evaluated. The character of friction surfaces was confirmed by SEM. The sample with 5.6 vol% of Al2O3 offers the best tribological property among the prepared formulations, and is characterized by high and steady friction coefficient (about 0.45) and low wear. With the temperature increasing, the stibnite patches population on friction surface increases and individual steel fibers spread due to their plastic deformation to form larger primary contact plateaus. The area covered by contact primary plateaus decreases with the alumina content increasing. 相似文献