| In recent years, along with the environmental protection consciousness enhancement by human, it has become an urgent matter to find a substitute for asbestos fiber as reinforcing materials of brake pads. Potassium titanate whiskers played a very important role in a composite reinforced material, friction materials, catalyst carrier, and many other fields for its excellent mechanical properties and unique chemical properties. Especially when synthesis of potassium titanate whisker has a larger breakthrough, potassium titanate whisker is considered to be the best substitute for asbestos fibers. But the large-scale industrial production are mainly composed of sintering process, has many shortcomings such as a large energy consumption, and uneven surface morphology. Therefore, improving the production process to preparation potassium titanate whiskers used in friction materials with high length to diameter ratio with low energy consumption method is the important topic in the field of study. Based on epoxide-mediated sol-gel method combined with the sintering method, potassium titanate whisker were prepared, in order to design non-asbestos brake pads of green environmental protection formula with no copper and less-metallic the above two research direction contained, we obtained the following results:1. Sol-gel method with synthesis process of potassium titanate whiskers can reduce the sintering temperature, increasing length to diameter ratio of the whiskers when propylene oxide as a gelling agent,TiCl4 and CH3COOK as raw materials, which showed when the molar ratio of K/Ti is 1:3, calcination condition is at 1000℃ for 5 hours, the average length of potassium titanate whiskers synthesized is about at 4 μm, length to diameter ratio is about 12, good crystallinity of the crystal with a uniform morphology.2.The reinforcing formulation with potassium titanate whiskers and other fibers, potassium titanate whiskers and aramid hybrid having different influence on the mechanical properties and tribological properties of brake pads were discussed. Using metal sulfide and friction modifier performance and high thermal conductivity fibers may be partially or completely replace the role of copper in friction materials. When potassium titanate whiskers and aramid ratio of 1:4 was added in formulation of brakes pads, constant speed friction test machine at a temperature in the range of 100 ～350℃, the friction coefficient fluctuate within a small range of 0.33 to 0.43 and the lowest average of wear rate, bench test results showed that the brake pad with a good thermal recession resistance performance and a good recovery performance.3.Preparation and characterization of multi-reinforced NAO brake pads. It shows that two-dimensional flake graphite network skeleton, cross, interconnected whisker reinforcement body is connected, zero-dimensional cenospheres, etc. fill the structure of gap, form a stable three-dimensional network structure; provide a stable friction coefficient, and a higher and more stable friction and wear properties for the friction materials.With the preparation of epoxide-mediate sol-gel method combined with sintering method, not only greatly reduces the sintering temperature of the potassium titanate, but also uniform morphology and good dispersion obtained at the same time; With potassium titanate whisker reinforced material preparation of brake pads, not only improving the high temperature wear resistance and stability of the high temperature coefficient of friction, avoiding the high temperature and friction heat recession. Improving the security of braking process. |
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