WC基硬质合金的性能及其在硬密封球阀的应用研究

发布时间：2018-03-25 04:08

本文选题：硬密封球阀　切入点：耐磨耐蚀性能　出处：《兰州理工大学》2017年硕士论文

【摘要】：球阀作为截止阀的一种,除了应用于一般的工业管道,在西气东输、煤制油工程、宇航工业上也发挥着重要的作用。目前硬密封球阀存在腐蚀、强磨损而造成使用寿命过短问题,因此延长球阀的使用寿命已成为当下的研究热点。本文将WC基硬质合金用于球阀的球体和阀座,并对其在实际工况下的使用做了初步探究。本文采用低压烧结技术制备四种成分的WC基硬质合金,并且合金中采用了Co基和Ni基两种粘结剂。合金中WC的含量分别为84%,88%,90%和92%,对应的Co基粘结相的含量分别为14%和10%,Ni基粘结相的含量分别为8%和6%。运用光学显微镜(OM)、扫描电镜(SEM)、能谱(EDS)、X线衍射(XRD)等研究合金组织结构和物相组成,利用显微硬度计测量合金的硬度,万能电子试验机测定其抗弯强度,利用表面综合性能测试仪测定合金的耐磨损性能,利用电化学工作站测定的耐腐蚀性能,对合金制成的球体和阀座进行了开关实验测定其使用寿命,分析实验结果,可以得出如下结论。(1)低压烧结出组织纯净的纳米级WC基硬质合金,合金晶粒尺寸随WC含量的上升而增大。合金的硬度随着WC含量的增加而增大,抗弯强度则与WC的含量无关。(2)随着WC的含量升高,合金的耐磨损性能加强。低载荷下,合金几乎不发生磨损;中载荷下,合金的磨损机理是磨粒磨损;高载荷下,合金主要磨损机制为粘着磨损。(3)常温条件下,WC-6Ni和WC-14Co满足耐磨球阀的需求,因而投入生产并用于球阀的阀座和角阀内部。低温条件下,温度从20℃降到-110℃,WC基硬质合金的硬度有轻微上升,然而在-196℃时硬度大幅下降,因而合金不适用于超低温下的工况。(4)在酸性介质中合金的耐腐蚀性能为:WC-14CoWC-10CoWC-8NiWC-6Ni。在碱性介质中合金的耐腐蚀性能为:WC-10CoWC-6NiWC-8NiWC-14Co。在中性介质的耐腐蚀性能为:WC-14CoWC-10CoWC-6NiWC-8Ni。WC基硬质合金的耐腐蚀性十分优秀,在三种介质中耐腐蚀性分别为:酸性介质中性介质碱性介质。因而碱性环境中时可以重点考虑采用WC基硬质合金制备的阀门。
[Abstract]:Valve as a shut-off valve, in addition to the application in industrial pipeline in general, in the west east gas pipeline, coal oil project, the aerospace industry has played an important role. At present, the hard seal ball valve corrosion, strong wear caused by short service life, thus prolonging the service life of the ball valve has become a hot research topic at the moment. The WC based hard alloy for ball valve and valve seat, and its use in actual conditions and made a preliminary inquiry. The preparation of WC based hard alloy four components by low pressure sintering technology, and the alloy with Co based and Ni based two kinds of binder content in the alloy WC. Were 84%, 88%, 90% and 92%, corresponding to the Co based bonded phase content were 14% and 10%, the Ni based bonded phase content is 8% and 6%. respectively by optical microscope (OM), scanning electron microscopy (SEM), energy spectrum (EDS), X-ray diffraction (XRD) of alloy organization The phase composition and structure, microhardness tester measuring the hardness of the alloy, electronic universal testing machine and its flexural strength, wear resistance determination of alloy by comprehensive performance tester surface was measured by electrochemical workstation, the corrosion resistance of alloy ball and seat to switch the experimental measurement of service life analysis the experimental results, we can draw the following conclusions. (1) low pressure sintering microstructures of pure nanometer WC based hard alloy, the alloy grain size increased with the increase of the content of WC. The hardness of the alloy increases with the increase of WC content, the bending strength has nothing to do with the content of WC. (2) with the increase of WC content and strengthen the wear resistance of the alloys. Under low load, there is almost no alloy wear; in load, the wear mechanism of the alloy is abrasive wear; under high load, the main wear mechanism is adhesive wear alloy. (3) at room temperature. Under WC-6Ni and WC-14Co meet the needs of the wear-resistant ball valve, put into production and for the valve seat and valve angle valve inside. Under the condition of low temperature, temperature from 20 degrees down to -110 DEG C, WC based cemented carbide hardness has increased slightly, but the hardness at -196 DEG C greatly decreased, thus not suitable for super alloy under low temperature conditions. (4) the corrosion resistance of the alloy in acidic medium, the corrosion resistance of WC-14CoWC-10CoWC-8NiWC-6Ni. alloy in alkaline medium: WC-10CoWC-6NiWC-8NiWC-14Co. in neutral medium corrosion resistance: WC-14CoWC-10CoWC-6NiWC-8Ni.WC hard alloy corrosion resistance is very good, in three kinds of medium corrosion resistance were: acid medium and neutral medium in alkaline medium. So it can be considered by WC based cemented carbide prepared by the valve in an alkaline environment.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH134;TG135.5

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