| Phenol-formaldehyde resin(PF)is used as a matrix for the preparation of friction materials due to its excellent thermal stability,high coke yield,and excellent solvent resistance.However,the application of phenolic resin-based friction materials is limited due to relatively poor wear resistance.Titanate whiskers with excellent mechanical and wear resistance are one of the good reinforcing materials of polymer matrix.In this paper,alumina and silica modified titanate whiskers were used and compounded with phenolic resin.The mechanical and friction properties of phenolic/titanate whisker composites were mainly studied.The titanate whiskers were successively modified with alumina and silica multiply inorganic oxides,and the silica-modified titanate whiskers and unmodified whiskers were used as controls.The obtained whiskers were mixed with the resin uniformly according to different ratios,and the phenolic/titanate whisker composite was prepared through a compression molding process.The cross-sectional morphology of the composite showed that the modification of the multiply inorganic oxide improved the dispersion of whiskers in the matrix,enhanced the interface adhesion,and was beneficial to improve the mechanical friction properties of the composite.After the whiskers were added,the density,hardness and thermal decomposition temperature of the composite increased.The mechanical performance results showed that the composites filled with alumina and silica modified whiskers exhibited a flexural strength of up to 91.7±2.7 MPa and a maximum compressive strength of 257.0±6.8MPa,increasing by 29.2%and 5.8%compared with PF,respectively.Tribological performance results revealed that when containing 7.5 wt%of multiply inorganic oxides modified whiskers,the wear rate of the composite was reduced to 0.49×10-5mm3/Nm,which was significantly lower than that of phenolic resin(4.79×10-5mm3/Nm).In addition,the addition of whiskers also improved the friction stability of the composite.The worn surface of the composites detected by a scanning electron microscope showed that the wear mechanism of PF was fatigue wear,while the whisker-filled composite showed abrasive wear and slight fatigue wear.Optical microscope images indicated that the whisker-filled composite had a shallow scratch on the worn surfaces,which positively favored wear resistance. |
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