【摘要】：鐵路貨車用閘瓦(剎車片)基本結(jié)構(gòu)是由鋼背和高分子基復(fù)合摩擦材料鉚接組成。每年公路交通貨車、農(nóng)用貨車和工礦機械產(chǎn)生的閘片數(shù)量巨大。廢舊閘瓦作為垃圾,既是資源的浪費,同時不易降解的高聚物也對環(huán)境造成了極大危害。因此,廢舊貨車閘瓦的回收循環(huán)再利用對保護環(huán)境、節(jié)約資源是至關(guān)重要的研究課題。本論文針對鐵路貨車廢舊閘瓦的回收循環(huán)再利用進行了研究,主要包括廢舊閘瓦鋼背與摩擦材料的分離造粒工藝和回收摩擦材料的再利用研究兩大內(nèi)容。廢舊閘瓦的分離造粒采用壓力機直接加壓及熱裂解分離造粒兩種工藝,并對回收料的粒度、成分進行了分析。通過在廢舊閘瓦摩擦材料中重新添加酚醛樹脂、鋼纖維等新的組分,進行配方和成型工藝設(shè)計,對新制備的摩擦材料進行摩擦磨損性能、彎曲強度和硬度等性能試驗,并用掃描電鏡(Scanning Electron Microscopy,SEM)對磨屑、磨損表面及斷口進行了摩擦磨損機理分析。壓力機直接加壓分離廢舊閘瓦的方法,工藝流程簡單,但分離不完全、效率低下;熱裂解分離造粒工藝需要高溫缺氧的條件、流程復(fù)雜,但污染小、可直接獲得粉碎料、適合大批量閘瓦的回收利用。與壓力機直接加壓分離廢舊閘瓦相比,熱裂解技術(shù)分離造粒廢舊閘瓦得到的粉末回收料的粒徑較小,且分布比較集中。貨車閘瓦在使用后,組分中仍存在著無機礦物鋁釩土、重晶石、鉀長石粉、海泡石、鐵粉或鋼纖維以及硫磺;貨車閘瓦在反復(fù)摩擦制動過程中,有機基體(酚醛樹脂)組分碳化和軟化,有機基體失效,不能起到基體的連接作用。廢舊閘瓦回收摩擦料再利用的合適組分范圍:回收摩擦料含量為70~72.5wt%,腰果殼油改性酚醛樹脂含量為7.5~10 wt%,鋼纖維的含量為3 wt%,填料中二硫化鉬為1 wt%,石墨為5 wt%,促進劑和硬脂酸為1 wt%;熱壓成型工藝為:在160℃、20 MPa下熱壓,保壓時間根據(jù)制品的厚度1~1.5 min/mm確定;固化工藝為:在120℃下干燥12 h。材料在100~300℃時的摩擦系數(shù)穩(wěn)定在0.30~0.50之間,磨損率小于0.75×10-7 cm3/(N·m),回收料再利用對摩擦磨損性能并無大的降低。試驗的平均硬度在50~77 HRR之間,彎曲強度≥24.5 MPa。在低溫條件下,試樣的磨損主要表現(xiàn)出磨粒磨損;在高溫條件下,主要表現(xiàn)為粘著磨損。
[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，

本文編號：2198477