铁路货车废旧闸瓦摩擦材料的回收再利用研究

发布时间：2018-08-23 08:23

【摘要】：铁路货车用闸瓦(刹车片)基本结构是由钢背和高分子基复合摩擦材料铆接组成。每年公路交通货车、农用货车和工矿机械产生的闸片数量巨大。废旧闸瓦作为垃圾,既是资源的浪费,同时不易降解的高聚物也对环境造成了极大危害。因此,废旧货车闸瓦的回收循环再利用对保护环境、节约资源是至关重要的研究课题。本论文针对铁路货车废旧闸瓦的回收循环再利用进行了研究,主要包括废旧闸瓦钢背与摩擦材料的分离造粒工艺和回收摩擦材料的再利用研究两大内容。废旧闸瓦的分离造粒采用压力机直接加压及热裂解分离造粒两种工艺,并对回收料的粒度、成分进行了分析。通过在废旧闸瓦摩擦材料中重新添加酚醛树脂、钢纤维等新的组分,进行配方和成型工艺设计,对新制备的摩擦材料进行摩擦磨损性能、弯曲强度和硬度等性能试验,并用扫描电镜(Scanning Electron Microscopy,SEM)对磨屑、磨损表面及断口进行了摩擦磨损机理分析。压力机直接加压分离废旧闸瓦的方法,工艺流程简单,但分离不完全、效率低下;热裂解分离造粒工艺需要高温缺氧的条件、流程复杂,但污染小、可直接获得粉碎料、适合大批量闸瓦的回收利用。与压力机直接加压分离废旧闸瓦相比,热裂解技术分离造粒废旧闸瓦得到的粉末回收料的粒径较小,且分布比较集中。货车闸瓦在使用后,组分中仍存在着无机矿物铝钒土、重晶石、钾长石粉、海泡石、铁粉或钢纤维以及硫磺;货车闸瓦在反复摩擦制动过程中,有机基体(酚醛树脂)组分碳化和软化,有机基体失效,不能起到基体的连接作用。废旧闸瓦回收摩擦料再利用的合适组分范围:回收摩擦料含量为70~72.5wt%,腰果壳油改性酚醛树脂含量为7.5~10 wt%,钢纤维的含量为3 wt%,填料中二硫化钼为1 wt%,石墨为5 wt%,促进剂和硬脂酸为1 wt%;热压成型工艺为:在160℃、20 MPa下热压,保压时间根据制品的厚度1~1.5 min/mm确定;固化工艺为:在120℃下干燥12 h。材料在100~300℃时的摩擦系数稳定在0.30~0.50之间,磨损率小于0.75×10-7 cm3/(N·m),回收料再利用对摩擦磨损性能并无大的降低。试验的平均硬度在50~77 HRR之间,弯曲强度≥24.5 MPa。在低温条件下,试样的磨损主要表现出磨粒磨损;在高温条件下,主要表现为粘着磨损。
[Abstract]:The basic structure of brake shoe for railway freight car is riveted with steel back and polymer-based composite friction material. Every year, the number of gates produced by road traffic trucks, agricultural trucks and industrial and mining machinery is enormous. The waste brake shoe is not only a waste of resources, but also a great harm to the environment. Therefore, recycling and recycling of used brake shoe is a very important research topic to protect environment and save resources. In this paper, the recycling and recycling of railway freight car used brake shoe is studied, including the separation and granulation process of steel back and friction material and the reuse of recycled friction material. The separation granulation of waste brake shoe is made by pressing directly by press and separating granulation by pyrolysis. The granularity and composition of recycled material are analyzed. By adding new components such as phenolic resin and steel fiber into the friction material of waste brake shoe, the formula and forming process were designed, and the friction and wear properties, bending strength and hardness of the new friction material were tested. The friction and wear mechanism of wear debris, wear surface and fracture surface were analyzed by scanning electron microscope (Scanning Electron). The method of separating waste brake shoe directly by press is simple, but the separation is not complete and the efficiency is low. The pyrolysis separation granulation process needs the condition of high temperature and anoxia, the process is complicated, but the pollution is small, so the comminuted material can be obtained directly. Suitable for large-batch brake shoe recycling. Compared with the direct pressure separation of waste brake shoe by press, the particle size and distribution of powder recovery material obtained by pyrolysis technology are smaller and more concentrated. After the truck brake shoe is used, the inorganic mineral aluminum vanadium soil, barite, potassium feldspar powder, sepiolite, iron powder or steel fiber and sulphur still exist in the components. Organic matrix (phenolic resin) component carbonation and softening, organic matrix failure, can not play the role of matrix bonding. Suitable range of components for recovery of friction materials from waste brake shoe: the content of recovered friction material is 70 ~ 72.5 wt., the content of modified phenolic resin in cashew shell oil is 7.5 ~ 10 wt, the content of steel fiber is 3 wt, the content of molybdenum disulfide in filler is 1 wtt, graphite is 5 wt. The process of hot pressing is as follows: hot pressing at 160 鈩，

本文编号：2198477