Paper-based Friction Materials Research Articles

Investigation of the thermal property and tribological behavior of CaSO4 whisker-modified paper-based composite friction materials

In this study, CaSO4 whisker was applied to the paper-based composite friction material as the friction layer (secondary layer) by the paper-making process. The tribological and thermal properties were analyzed. Three-dimensional surface profiles were observed to discuss the wear mechanism. The results showed that the samples with higher CaSO4 whisker contents owned better thermal resistance. The sample with 4% CaSO4 whisker content had the highest dynamic friction coefficient. As the CaSO4 whisker content increased from 0% to 16%, the wear rate decreased first and then increased, and the sample with 8% CaSO4 whisker content had the highest wear resistance.

Sol–gel synthesis of nanosilica-coated para-aramid fibers and their application in the preparation of paper-based friction materials

A facile method of surface modification to fabricate nanosilica-coated aramid fibersviasol–gel process and their application for paper-based friction materials by wet-forming process.

Measurement of adsorption energy between a solid adsorbent and a liquid adsorbate using differential scanning calorimetry

We report on a novel method involving the use of differential scanning calorimetry (DSC) in evaluation of adsorption energy between a liquid adsorbate and a solid adsorbent. The proof of concept is demonstrated by measuring the exothermic heat release due to the adsorption of automotive transmission fluid (ATF), the adsorbate, to a paper-based friction material used in automotive torque converters, the adsorbent. The novelty of the measurement technique involves initial freezing of the liquid adsorbate so that the initiation of the adsorption process can be identified. Our experimental results and theoretical calculations reveal that the adsorption energy of the friction paper and the summation of adsorption energies of each friction paper ingredient are in good agreement.

Effects of NBR Particle Size on Performance of Carbon Fiber–Reinforced Paper-Based Friction Material

In the present work, three different sized nitrile–butadiene rubber (NBR) particles were used to modify carbon fiber–reinforced paper-based friction material (CFRPF). The effects of NBR particle size on performance of CFRPF were studied. The microstructure and properties of the samples were investigated by scanning electron microscopy, thermal analysis, and wet friction performance testing. Experimental results indicated that there were four stages in the thermal degradation of NBR-modified CFRPF. NBR particle size had a great effect on the first degradation stage (100–300°C). The highest friction coefficient was obtained with the sample containing the finest NBR particles. The wear rate of the friction materials decreased with an increase in NBR particle size. However, NBR particle size had little influence on the wear rate of the couple plate. The sample containing coarse NBR particles showed excellent friction stability under oil-lubricated conditions.

A statistical model for evaluating the tribological properties of paper-based friction materials

In order to synthetically evaluate the tribological properties of friction materials, fuzzy comprehensive evaluation model was developed. The analytic hierarchy process was introduced into the model to establish weight function. The paper-based friction materials with different CNTs content were chosen as the six projects. It is found that the comprehensive evaluation indexes are increased by 126–307% for the samples with 4–15wt% of CNTs compared with the sample without CNTs. The judgment matrix has high consistency by consistency checking. And the evaluation results are also in accordance with the results obtained through the friction torque, surface structure and temperature.

Fatigue property in paper-based friction materials under out-of-plane compressive loading

This paper deals with fatigue behavior of paper-based friction materials under cyclic compression to tension loading and damage behavior under cyclic compressive loading. The fatigue tests under out-of-plane compressive stress to slight tensile stress loading are conducted to evaluate fatigue strength of friction materials. The tests under cyclic out-of-plane compressive loading are also conducted to investigate influence of compressive stress and load cycles on damage behavior. Two kinds of friction materials are composed of aramid-based fiber and phenolic resin, and cellulose fiber and phenolic resin. Their fatigue strengths decrease with increasing load cycles. The damage density in both materials increases with increasing compressive stress and load cycles.

Effect of carbon fiber content on the friction and wear performance of paper-based friction materials

In order to get homogeneous pores distribution of friction materials, four kinds of micron-level carbon fibers reinforced paper-based friction materials were prepared. Experimental results showed that the porosity of samples decreased with the increase of carbon fiber content. Pores formed in micrometer-level fibers reinforced friction materials were more regular than friction materials reinforced by millimeter-level fibers. The tensile strength of samples decreased with the increase of carbon fiber content. The wear rate of samples increased with the increase of carbon fiber content. The sample with 55% carbon fibers exhibited the best friction stability and anti-shudder performance under oil lubricated conditions.

OS1326-271 高温環境下において面外圧縮負荷を受けるペーパー系摩擦材の微視損傷評価

This paper deals with investigation on microscopic damage in paper-based friction materials subjected to compressive loading at elevated temperature to clarify influence of temperature on damage. Two kinds of paper-based friction materials which were composed with aramid fiber, cellulose fiber and phenolic resin were used. The compressive tests were conducted at room temperature (R.T.) and 120℃ in air. After the tests, damage initiated during the fatigue tests was observed. Damage density in both materials increased with increasing load cycles for all conditions, and damage density also increased with elevating temperature. The paper-based friction materials were susceptible to damage at elevated temperature. From a viewpoint of the constituents, damage density in the cellulose-based material was much higher than in the aramid-based material.

Effects of Microscale Texture on the Tribological Behavior of Paper-Based Friction Materials for a Wet Clutch

Effects of Microscale Texture on the Tribological Behavior of Paper-Based Friction Materials for a Wet Clutch

Distinguishing the effects of adhesive wear and thermal degradation on the tribological characteristics of paper-based friction materials under dry environment: A theoretical study

Adhesive wear and thermal degradation are the main aging mechanisms of paper-based friction materials. However, how these aging mechanisms affect the tribological characteristics of such materials is not fully understood. In this paper, the respective influences of the two aging mechanisms on the tribological characteristics of the friction materials are investigated through simulation. It is assumed that adhesive wear pre-dominantly affects the surface topography, while thermal degradation significantly affects the mechanical properties of the friction material. The simulation results show that the static friction coefficient and both normal and tangential contact stiffnesses increase due to adhesive wear, but decrease due to thermal degradation. These trends are qualitatively in agreement with experimental observations reported in the literature and our previous work.

Effects of carbon fiber length on the tribological properties of paper-based friction materials

Four kinds of paper-based friction materials reinforced with carbon fibers of 100, 400, 600 and 800μm were prepared by paper-making processes. Experimental results showed that the friction materials became porous with fiber length increasing. The friction torque curves were flat except the sample with 100μm fibers. The wear rate of the sample with 100μm fibers was only 1.40×10−5mm3/J. Tiny debris and fine scratches formed in the worn surface were the reason for excellent wear resistance of friction pairs with 100μm fibers. The friction pairs with 400, 600 and 800μm fibers showed typically abrasive wear and fatigue wear.

1104 接触面内における湿式クラッチ用ペーパー摩擦材の構成要素の判別(OS11-1 機械要素とトライボロジー,オーガナイズドセッション11:「機械要素とトライボロジー」)

1104 接触面内における湿式クラッチ用ペーパー摩擦材の構成要素の判別(OS11-1 機械要素とトライボロジー,オーガナイズドセッション11:「機械要素とトライボロジー」)

Influence of compound mineral fiber on the properties of paper-based composite friction material

Paper-based composite friction material is a kind of key functional material for automatic transmission. In this study, five types of paper-based composite friction materials with different compound mineral fiber contents were prepared using the paper-making process. The effect of compound mineral fiber content on the properties such as shear strength, thermal property, friction torque curves, dynamic friction coefficient and wear resistance was studied. Meanwhile, the sensitivity of the friction coefficients was also investigated. Worn surfaces of samples were analyzed using scanning electron microscope. Experimental results revealed that the thermal properties of the samples were improved as the compound mineral fiber content increased and the shear strength increased initially and then decreased. The friction torque curve of the sample with 20% compound mineral fiber contents was the highest among all the samples and the sample with higher compound mineral fiber contents possessed the more flat friction torque curve during the mixed asperity contact phase of the engagement process. The dynamic friction coefficient increased with the increase of compound mineral fiber content and decreased as contact pressure and rotating speed increased. The wear resistance of the sample was highest when the compound mineral fiber content was about 15%.

Influence of Adhesive Wear and Thermal Degradation on the Frictional Characteristics of Paper-Based Friction Materials: A Comparative Study

This paper discusses the effects of adhesive wear and thermal degradation on the dry frictional characteristics of paper-based friction materials against steel material. Some commercial paper-based friction materials typically used for clutch applications were subjected to adhesive wear and thermal degradation and the dry frictional characteristics were then measured at different states on a rotational tribometer. The experimental results reveal that both adhesive wear and thermal degradation have opposite effects on the frictional characteristics, where the static and kinetic coefficients of friction increase due to adhesive wear but decrease due to thermal degradation.

OS0908 繰返し面外圧縮負荷を受けるペーパー系摩擦材の微視損傷挙動に及ぼす負荷応力及び繰返し数の影響

OS0908 繰返し面外圧縮負荷を受けるペーパー系摩擦材の微視損傷挙動に及ぼす負荷応力及び繰返し数の影響

Shear-Compressive Strength and Fatigue Properties of Paper-Based Friction Materials

Shear-Compressive Strength and Fatigue Properties of Paper-Based Friction Materials

S115013 湿式クラッチ用ペーパー摩擦材の摩擦中における真実接触部の観察

A Paper-based friction material has been used in the wet clutch with automatic transmission fluid (ATF) in order to obtain good friction characteristics, however friction behavior of wet clutch is not sufficiently clarify. In this study, paper-based friction materials were rubbed with ATF using a pin-on-disk type tribometer and the contact area between the prism and the paper-based friction materials was observed using the total reflection optical system. Two kinds of paper-based friction materials, poly-para-phenylen terephthalamide (PPTA) fiber-filled friction materials and PPTA + carbon fiber-filled friction materials were used. As a result, it was found that coefficient of friction tend to increase and real contact area tend to be constant as the sliding speed increased. In addition, both coefficient of friction and real contact area tend to increase as the increasing the contact pressure.

OS0106 面外圧縮負荷を受けるペーパー系摩擦材の疲労強度と損傷挙動の関係性に関する研究

OS0106 面外圧縮負荷を受けるペーパー系摩擦材の疲労強度と損傷挙動の関係性に関する研究

Evaluation of Debonding Fracture Toughness of Paper-Based Friction Materials by Double-Cantilever Beam Specimen

Evaluation of Debonding Fracture Toughness of Paper-Based Friction Materials by Double-Cantilever Beam Specimen

Effect of Graphite Particle Size on Friction and Wear Performance of Paper-based Friction Material

Paper-based friction materials containing four different graphite particle sizes were prepared using the wet paper-making process. The effects of graphite particle size on friction performance such as friction torque curves, dynamic friction coefficient, static friction coefficient and wear rate were studied by using an inertia friction tester. Meanwhile, the sensitivity of friction coefficient to braking pressure and rotating speed was also investigated. Worn surfaces of samples were analyzed by using scanning electron microscope. The results show that with graph- ite particle size decreasing, braking time increases and torque curves become more stable, while friction coefficient and wear rate decrease. The dynamic friction coefficient declines as braking pressure and rotating speed increase. Samples with proper particle size exhibit more stable friction coefficient in the continuous braking process. Lubri- cating film is formed to lower wear rate in the worn surface as the graphite particles size decreases.