Mass fraction of 1.5%, 3% of the nanomontmorillonite (MMT) were separately added in the phenol prepolymer, phenolic resin/ MMT was synthesized by in-situ method (it is called PF/M). The PF/M was carried out TG analysis using thermal analyser, and the synthetic resin PF/M were as new resin matrix to prepare semimetallic friction material, tribological performance test was carried on XD-MSM fixed speed type friction-wear testing machine in accordance with the GB_5763-2008. The results show that the heat resistance of composite PF/M and tribological performance of friction material are best when nanoMMT is 3% in the resin, the Carbon residue rate of PF/M is an increase of 37% compared with PF without nanoparticles at 600°C, thermal recession temperature of sample by the preparation of PF/M increases above 100°C, and it has stable friction coefficient, overall wear rate decreases 26%, especially in high temperature stage at 350°C, the wear rate decreases significantly, its wear rate decreases 30%.
A type of phenolic resin (PF) was prepared by using TiO2 nanoparticles modified with KH-550 as composite filler and modifier, and then the composite modified PF were used as adhesive to prepare semi-metallic friction materials samples. TG analysis of the prepared nano-TiO2 /PF composites was conducted on SETARAM-TG2DSC92216 thermal analyzer that was made in France, and the friction and wear property comparison tests of the samples were carried out on XD-MSM fixed speed friction-wear machine. The results show that the heat resistance of phenolic resin after being compositely modified by TiO2 nanoparticles can be improved, carbon residue rate increases10% at 600°C;the friction coefficient of the corresponding sample slightly increases;the wear rate clearly decreases at high temperature, and wear rate decreases 10% at 350°C.
The orthogonal experimental study is carried out to study the Incorporation of different proportion of functional components and the effect on tribological performance among semi-metallic friction materials. A test is conducted for each sample on XXD-MSM constant speed tester in accordance with Brake Linings for Automobiles (GB5763-2008). The friction factor and high-temperature abrasion resistance properties are evaluated along with the obtaining of optimal formula, and the mechanism of affecting the tribological properties is analyzed on the worn surfaces by using a scanning electron microscope (SEM). The study results indicate that the high-temperature friction stability could be deeply affected by the adequate content of steel fiber, Kevlar pulp, potassium hexatitanate whisker and cashew nut shell. The mechanism of High-temperature tribological behaviors are the thermal decompositions. The thermal decomposition of organic matter might greatly weakened the bonding effect. The thermal decomposition of tribo-film fall off as lamellar chip under the effect of friction stress. The addition level of nanoparticles is 3%, the sample’s tensile strength, tensile strength, hardness index and noise level are better. If the modified resin is further applied, this formula can be close to the index of excellent Chinese industrial product JF04-20.
The silane coupling agent KH550 is used to modify foamed Fe powder(FFP) surface for obtain the hydrophobic surface, which is the very important component in semi-metallic friction material. It can improve high temperature bonding force between FFP and phenolic resin, further improve friction coefficient stableness of friction material and abrasion resistance. The modification effect of FFP is characterized by IR, and the tribological properties is characterized by XD-MSM constant speed friction test machine, the surface topography is characterized by SEM. The results indicate that FFP has been bonded to silane coupling agent, and formed hydrophobic surface what has the alkyl group. The changing of friction coefficient has reduced 23%, the average wear rate has declined 28.6%,and the wear rate has declined 32% at 350 °C after the friction material with modified FFP compare with the one with original FFP. And those changing are all because of the fact that the FFP modified by KH550 is difficult to peel off during the high temperature.
We discuss two methods of preparation and modification on nanoMMT, one is called “one-step method”, and another is called “two-steps method”. And then we use the IR, TEM, XRD, granulometer and sedimentation to test the effect of modification. The result shows that two methods can also modify nanoMMT, but the nanoMMT made by “one-step method” in lubricate oil is more stable and dispersed than another’s. Average grain diameter of nanoMMT made by “one-step method” in lubricate oil is 46nm, while another’s is 69.75nm. Also, it’s layer distance has expanded from 1.52nm to 2.10nm.
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