Tribological Evaluation of an Al2O3-SiO2 Ceramic Fiber Candidate for High Temperature Sliding Seals

A test program to determine the relative slitting durability of an alumina-silica candidate ceramic fiber for high temperature sliding seal applications is described. Pin-on-disk tests were used to evaluate the potential seal material by sliding a tow or bundle of the candidate ceramic fiber against a superalloy test disk. Friction was measured during the tests and fiber wear, indicated h the extent of fibers broken in the tow or bundle, was measured at the end of each test. Test variables studied included ambient temperature from 25° to 900°C, loads from 1.3 to 21.2 N, and sliding velocities from 0.025 to 0.25 m/sec. In addition, the effects of fiber diameter and elastic modulus on friction and wear were measured. Thin gold films deposited on the superalloy disk surface were evaluated in an effort to reduce friction and wear of the fibers.

In most cases, wear increased with test temperature. Friction ranged from 0.36 at 500°C and low velocity (0.025 miser) to over 1.1 at 900°C and high velocity (0.25 m/sec). The gold films resulted in satisfactory lubrication of the fibers at 25°C. At elevated temperatures diffusion of substrate elements degraded the films. These results indicate that the alumina-silica (Al₂O₃SiO₂) fiber is a good candidate material system for high temperature sliding seal applications. More work is needed to reduce friction.     

钢纤维和莫来石纤维增强陶瓷基摩擦材料的性能研究

采用热压烧结法制备出钢纤维和莫来石纤维增强陶瓷基摩擦材料,对比分析钢纤维、钢纤维和莫来石纤维的混杂纤维以及莫来石纤维增强陶瓷基摩擦材料的机械性能和摩擦磨损特性。利用扫描电子显微镜(SEM)观察不同温度下的磨损表面和磨屑形貌,并研究其磨损机制。研究结果表明,钢纤维和莫来石陶瓷混杂纤维增强的陶瓷基摩擦材料具有较高的机械强度以及良好的摩擦稳定性和耐磨性能,以莫来石纤维增强的陶瓷基摩擦材料,摩擦因数表现出严重的热衰退,且具有低的耐磨损性能。SEM分析表明,在从低温到高温的摩擦过程中,钢纤维和莫来石陶瓷混杂纤维增强的陶瓷基摩擦材料的磨损形式主要由黏着磨损转化为黏着磨损与磨粒磨损的复合磨损形式,而以莫来石纤维增强的陶瓷基摩擦材料,其磨损形式以磨粒磨损为主。     

随行振动胶塞用芳纶纤维布复合材料的制备及摩擦磨损性能

针对石油钻井中使用的随行振动胶塞与套管、岩石摩擦磨损较大的问题,提出采用芳纶纤维布复合材料来增强随行振动胶塞的耐磨性.根据Bnierley经验公式法试织出6种不同经纬密度的试样织品,借助万能磨耗机试验研究织物不同经纬密度和不同摩擦转速对芳纶纤维布复合材料耐磨性的影响.结果表明:摩擦转速一定的条件下,织物经纬密度越大,芳...     

碳纤维改性热塑性聚酰亚胺材料摩擦磨损性能

通过正交实验设计和方差分析,系统考察了工况（温度、速度及载荷）对碳纤维改性热塑性聚酰亚胺（TPI）摩擦磨损行为的影响。用电子显微镜（SEM）观察其磨损面形貌分析材料磨损机制。研究表明：随着温度升高,分子链相对滑移增强,体现出良好的自润滑特性,材料的摩擦因数和磨损率均有所下降;排除摩擦热的干扰,方差分析表明载荷、速度及其交互作用对材料摩擦磨损行为影响不显著。根据粘着摩擦理论,载荷的改变对材料抗剪切强度无明显作用,表现为材料摩擦磨损性能稳定。随速度的增加,材料抗剪切强度呈现下降趋势,同时考虑到受力中的塑形硬化现象,摩擦因数出现先增后减的变化。     

A study of fiber-capstan friction. 2. Stick–slip phenomena

A study was made of the friction of nylon fiber (monofilament fishing line) rubbing against spinning aluminum and nylon capstans (cylinders), in the presence of various lubricants. Use of variable speed drives with appropriate gear reducers allowed variation of sliding speed over four orders of magnitude and monitoring of the entire Stribeck curves, from boundary through mixed to hydrodynamic sliding, for these systems. The effects on friction of seven system variables—cylinder material, sliding speed, system elasticity, input tension, lubricant viscosity, lubricant additives and cylinder surface roughness—were investigated. Special attention was given to the effects of elasticity on friction and the character of sliding. Factors which determine the critical speed where stick–slip sliding just appears or disappears are defined.     

多组分纤维混杂增强树脂基摩擦材料研究

为提高摩擦材料高温下的摩擦磨损性能和摩擦因数的稳定性,利用正交试验法对多种纤维增强酚醛树脂基摩擦材料的配方进行优化设计,并通过极差分析,探讨多种纤维及含量对摩擦材料性能的影响及摩擦材料的磨损机制.研究表明:混杂纤维增强树脂基摩擦材料有着优异的耐磨性.陶瓷纤维硬度较高,开散混料后能够均匀分布在树脂基体内,对酚醛树脂基摩擦...     

纹理表面滑动摩擦稳态摩擦学性能

基于稳态滑动摩擦系统模型,采用球-盘摩擦副定量分析研究法向载荷、滑动速度、初始表面纹理和摩擦副材料对稳态摩擦因数的影响,得到稳态摩擦因数在不同工况下的变化规律。结果表明：滑动摩擦的稳态摩擦因数与磨损率正相关,周向纹理表面的稳态摩擦因数最大,无纹理表面的稳态摩擦因数次之,径向纹理表面的稳态摩擦因数最小;无论何种初始表面形貌,随着转速的增加,稳态摩擦因数先减小后增大,随着法向载荷的增大,稳态摩擦因数呈增长趋势;较深较宽的表面纹理具有更大的稳态摩擦因数和更大的瞬时波动;稳态摩擦因数也与摩擦副材料的选取有关。     

SiCp增强铝基复合材料与Kevlar增强摩擦材料摩擦副摩擦磨损机理研究

采用盘销式摩擦磨损试验机，对SiCp含量为20vol％的铝基复合材料和Kevlar增强摩擦材料组成的摩擦副在于摩擦条件下的摩擦磨损机理进行了实验研究。结果表明：摩擦副在跑合过程中，铝基复合材料中的SiCp颗粒对较软的有机复合材料产生犁削和微观切削效应，磨损机理为铝基复合材料的硬质颗粒对较软的有机复合材料的磨粒磨损；在跑合后的磨损试验中，摩擦材料磨损表面呈现出粘着磨损和塑性变形特征，随着转动速度的增加，塑性流动加剧；摩擦副接触表面发生材料的相互转移，并在铝基复合材料表面形成转移膜，且在较高速度下转移膜更易形成；在高速条件下，摩擦材料表面可见从铝基复合材料的铝合金基体中脱离的SiCp颗粒和熔融迹象；摩擦材料的磨损机理主要为磨粒磨损、粘着磨损和塑性变形。     

口腔环境下巧克力摩擦性能影响的试验研究

为探讨口腔加工时间对典型高脂高糖食品的摩擦性能影响,开展口腔环境下巧克力摩擦性能的影响因素研究。以人工唾液和某品牌巧克力配制不同巧克力质量分数的混合溶液,改变聚二甲基硅氧烷(PDMS)基础液和固化剂的比例分别制备硬PDMS和含微凸体的软PDMS材料,基于陶瓷球对软PDMS和硬PDMS对软PDMS的两组摩擦副,在MFT-5000摩擦试验机上开展混合溶液在不同载荷和滑动速率的摩擦性能研究,讨论混合溶液与摩擦副的作用机制。结果表明:巧克力在口腔加工过程的摩擦性能与其质量分数、载荷、滑动速率和摩擦副等因素有关,随着巧克力质量分数的降低,巧克力的摩擦因数总体上是减小,这意味着消费者能够获得更好的丝滑感;载荷和滑动速率对巧克力摩擦性能的影响与摩擦副的选取有关,但滑动速率比载荷对其摩擦因数的影响更显著,研究结果为巧克力摩擦性能和口感的系统评价提供参考。     

颗粒增强铝基复合材料干摩擦磨损特性研究

采用自制的干摩擦磨损试验机研究了3种ZL101-SiCp、Al2O3p复合材料及对比材料与半金属摩擦材料配副的摩擦磨损性能.结果表明,随接触压力的增加,材料的磨损率增加;随摩擦速度的增加,材料的磨损率减小.ZL101合金的磨损率比复合材料要大近3个数量级.复合材料的磨损率仅为HT250的1/3.随接触压力、速度的增加,材料的摩擦系数降低.复合材料的摩擦系数与HT250的相当,摩擦系数稳定性优于HT250.     

钛酸钾晶须/芳纶/坡缕石复合矿物纤维摩擦材料的摩擦性能研究

混杂钛酸钾晶须、芳纶纤维、坡缕石纤维3种增强材料,复合制备一种非金属摩擦材料,运用正交试验法和极差分析法,研究各成分及其用量对材料摩擦性能的影响。结果表明:对材料的摩擦因数影响显著的顺序是芳纶纤维与坡缕石纤维交互作用,钛酸钾晶须,芳纶纤维,钛酸钾晶须与坡缕石纤维的交互作用,钛酸钾晶须与芳纶纤维的交互作用,坡缕石纤维。从磨损性来看,影响较大的因素是钛酸钾晶须,其次顺序是坡缕石纤维,芳纶纤维。最佳组合是钛酸钾晶须15%、芳纶纤维4%、坡缕石纤维15%。交互作用对材料的耐磨性影响显著的是芳纶纤维与坡缕石纤维,其次是钛酸钾晶须与芳纶纤维、钛酸钾晶须与坡缕石纤维。     

Hot wear properties of ceramic and basalt fiber reinforced hybrid friction materials

In the present study, hybrid friction materials were manufactured using ceramic and basalt fibers. Ceramic fiber content was kept constant at 10 vol% and basalt fiber content was changed between 0 to 40 vol%. Mechanical properties and friction and wear characteristics of friction materials were determined using a pin-on-disc type apparatus against a cast iron counterface in the sliding speeds of 3.2–12.8 m/s, disc temperature of 100–350 °C and applied loads of 312.5–625 N. The worn surfaces of the specimens were examined by SEM. Experiments show that fiber content has a significant influence on the mechanical and tribological properties of the composites. The friction coefficient of the hybrid friction materials was increased with increasing additional basalt fiber content. But the specific wear rates of the composites decreased up to 30 vol% fiber content and then increased again above this value. The wear tests showed that the coefficient of friction decreases with increasing load and speed but increases with increasing disc temperature up to 300 °C. The most important factor effecting wear rate was the disc temperature followed by sliding speed. The materials showing higher specific wear rates gave relatively coarser wear particles. XRD studies showed that Fe and Fe₂O₃ were present in wear debris at severe wear conditions which is indicating the disc wear.     

Effects of Ceramic Fiber on the Friction Performance of Automotive Brake Lining Materials

Friction material containing aluminum-silicon fiber was prepared. The effects of the aluminum-silicon fiber content on fade, recovery, and wear properties of the friction material were studied using a friction tester with a constant speed. Morphologies of the wear surfaces were observed by scanning electron microscopy (SEM). It was found that the heat fading resistance property of friction material was clearly improved when the content of aluminum-silicon wool was more than 5 wt.%, but the property of recovery declined and the wear rate increased slightly at the same time. The wear mechanisms were adhesive and abrasive, caused by the zircon sand, for the semi-metal friction material, while the abrasive wear of hybrid fiber reinforced composites was caused by cracked ceramic fibers and zircon sand.     

A Study of the Static/Kinetic Friction Behavior of PTFE-Based Fabric Composites

Three different polytetrafluoroethylene (PTFE)-based fabric composites were prepared. The static/kinetic friction behaviors of these composites under different loads and speeds were studied. A 3D laser microscope and profile measurement apparatus were used for analysis of the morphology and weave structure of the composites, and the contact temperature of these composites under different loads and speeds was monitored continuously using a high-precision thermal resistor. In addition, a dynamic mechanical analysis (DMA) apparatus was used to explore the thermal and mechanical properties of PTFE-based fabric composites. The results demonstrated that speed/load, weave structure, and fiber form have an important influence on static and kinetic friction behavior of the fabric composites. Generally, the static friction coefficient is greater than the kinetic friction coefficient, except when considering light load conditions. Under light load conditions, the static friction coefficient is equal to the kinetic friction coefficient. In addition, the kinetic friction coefficient first increased and then decreased with increased speed, but the static coefficient increased first and then remained at an almost constant value. At all sliding speeds, the static and kinetic friction coefficients of tape yarn composites are better than those of the multifilament yarn composites. Weave structure has no effect on the static friction coefficient, but it has a significant influence on the kinetic friction coefficient.     

纤维增强聚合物基摩擦材料的研究进展

阐述了纤维增强树脂基摩擦材料的摩擦磨损机制以及常用几种增强纤维的应用状况,综述了国内外目前纤维增强树脂基摩擦材料的研究现状,展望了纤维增强树脂基摩擦材料研究的发展趋势和前景.     

Frictional testing of wood—Initial studies with a new device

In the chip refining process used for mechanical pulp production, wood fibers are treated in a narrow gap between rotating plates. The process is energy consuming and much of the electrical energy supplied to the refiner is transferred to the fiber material through friction forces. Even though the importance of friction has been discussed frequently, little has been proven due to the complexity of the process and the process conditions. This paper presents a new apparatus for studying the frictional properties of wood, in lab-scale, under conditions which are aimed at simulating those prevalent in a chip refiner. Tests can be performed in saturated steam at high temperature/pressure with sliding velocities as high as 150 m/s. Studies at room temperature showed that the friction coefficient between spruce wood and smooth steel increased with the moisture content of the specimens. Impregnation by wood extractives lowered the friction coefficient for dry wood sliding at high speed. When tests were performed in a saturated steam environment, the frictional properties were affected and varied by the temperature of the surroundings. This is interesting in view of the fact that the friction coefficient is usually considered constant in analytical and numerical models of the process.     

Contributions of adhesion and hysteresis to coefficient of friction between shoe and floor surfaces: effects of floor roughness and sliding speed

Abstract

Improving shoe–floor friction in order to reduce slip and fall accidents requires thorough understanding of the factors that contribute to friction. The friction between a sliding viscoelastic material (shoe) and a hard surface (floor) has two major components: adhesion and hysteresis. This study aimed to quantify the effects of floor roughness and sliding speed on adhesion and hysteresis to determine how each component contributes to the coefficient of friction. Experiments were conducted on a pin on disc tribometer using ceramic tiles with three levels of roughness, six sliding speeds, two common shoe materials and four liquid lubricants. Hysteresis was measured using a lubricant that minimised adhesion. Dry and lubricated adhesion was measured by subtracting hysteresis from the coefficient of friction. Analysis of variance regression models were used to determine the contributions of hysteresis, dry adhesion, sliding speed and fluid to lubricated coefficient of friction. Increased floor roughness led to increased hysteresis, while increased sliding speed reduced both adhesion and hysteresis. These findings are consistent with theory that states that larger asperities increase hysteretic deformation and that sliding speed affects deformation and real area of contact between a viscoelastic material and a hard surface. The model correctly predicted 83% of variation in coefficient of friction based on dry adhesion, hysteresis and fluid dependent constants. The sensitivity of hysteresis friction to shoe material and floor roughness indicates that optimising these parameters may be effective at reducing slip accidents on oily floor surfaces.     

四种车辆制动闸瓦材料摩擦特性试验研究

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。     

Tribological evaluation of piston skirt/cylinder liner contact interfaces under boundary lubrication conditions

The friction and wear between the piston and cylinder liner significantly affects the performance of internal combustion engines. In this paper, segments from a commercial piston/cylinder system were tribologically tested using reciprocating motion. The tribological contact consisted of aluminium alloy piston segments, either uncoated, coated with a graphite/resin coating, or an amorphous hydrogenated carbon (a‐C : H) coating, in contact with gray cast iron liner segments. Tests were conducted in commercial synthetic motor oils and base stocks at temperatures up to 120°C with a 2 cm stroke length at reciprocating speeds up to 0.15 m s⁻¹. The friction dependence of these piston skirt and cylinder liner materials was studied as a function of load, sliding speed and temperature. Specifically, an increase in the sliding speed led to a decrease in the friction coefficient below approximately 70°C, while above this temperature, an increase in sliding speed led to an increase in the friction coefficient. The presence of a coating played an important role. It was found that the graphite/resin coating wore quickly, preventing the formation of a beneficial tribochemical film, while the a‐C : H coating exhibited a low friction coefficient and provided significant improvement over the uncoated samples. The effect of additives in the oils was also studied. The tribological behaviour of the interface was explained based on viscosity effects and subsequent changes in the lubrication regime, formation of chemical and tribochemical films. Copyright © 2010 John Wiley & Sons, Ltd.     

PEEK450 FC30与SiC陶瓷在海水润滑下的摩擦磨损特性研究

碳纤维增强聚醚醚酮PEEK450 FC30与工程陶瓷SiC软硬组合作为海水柱塞泵关键摩擦副备选材料,利用MCF 10摩擦磨损试验机对其在海水润滑下的摩擦磨损特性进行试验研究,探讨接触压力、滑动转速对材料磨损率和摩擦系数的影响规律。试验结果表明：在一定范围内的滑动速度、接触压力下,该摩擦副呈现出较小的磨损率和摩擦系数。当滑动速度在0.5~1.5 m/s之间,接触压力为1.33 MPa时,磨损率最小。通过扫描电子显微镜观察摩擦副磨损表层发现,在海水润滑下,SiC磨损并不明显,而PEEK450 FC30的磨损主要是以塑性涂抹为特征的粘着和SiC表面粗糙峰引起的机械犁耕。研究结果对水液压元件的选材具有十分重要的指导作用。