水煤浆喷嘴热冲蚀磨损机理研究

第23卷第5期摩擦学学报Vol 23, No 52003年9月TRIBOLOGYSep,2003水煤浆喷嘴热冲蚀磨损机理研究丁泽良2,李剑峰1,邓建新,艾兴,张德威2(1.山东大学机被工程学院,山东济南250061;2.株洲冼煤厂,湖南株洲412005)摘要:采用1Cr18NiTi不锈钢、YG8硬质合金和Al2O3/(W,Ti)C陶瓷3种材料制备了水煤浆喷嘴,考察了其在水煤浆雾化和燃烧过程中的热冲蚀磨损机理结果表明:喷嘴材料的硬度对水煤浆喷嘴的热冲蚀磨损行为具有重要影响在相同条件下,高硬度的A12O3/(W,TC陶瓷喷嘴的冲蚀率最低YG8硬质合金次之,硬度较低的1cr18NTi不锈钢喷嘴的冲蚀率最高;在热冲蚀磨损工况下,Cr18Ni9Ti不锈钢水煤浆喷嘴主要呈现微切削特征,YG8硬质合金水煤浆喷嘴主要呈现晶粒剥落特征,而A2O3(W,Ti)C陶瓷水煤浆喷嘴主要呈现研磨损伤和热崩特征,关键词:水煤浆;喷嘴;冲蚀磨损中图分类号:THl17.3文献标识码:A文章编号:104-0595(2003)05-044104水煤浆作为1种新型煤基代油液体燃料已广泛2.52g/cm3,平均粒径1m)和(W,T)C固溶体(株应用于我国电力、冶金和建材等行业的锅炉和窑炉.洲硬质合金厂提供,平均粒径1.5m)按一定配比进喷嘴是水煤浆燃烧器的关键部件之一,在水煤浆的雾行混合强化球磨(球磨后粉末平均粒径<0.8μm);化和燃烧过程中喷嘴发生严重热冲蚀磨损~4,为将混合粉末干燥后在流动氮气中过筛然后在氮气气了探索研制具有优良抗热冲蚀性能的水煤浆喷嘴,本氛中采用热压烧结工艺制备Al4O3/(W,Ti)C陶瓷材文作者分别选用Cr18NiTi不锈钢、YG8硬质合金料;烧结工艺参数:温度为1600~1800℃,压力为和A2O3/(W,Ti)C陶瓷3种材料制作了水煤浆喷32MPa,保温时间8~20min.同时采用标准YG型嘴,并对其进行了现场磨损试验,进而分析了其损伤硬质合金YG8和国际标准材质1Cr8NiTi不锈钢机理制备水煤浆喷嘴,其性能列于表1.1实验部分1.2冲蚀磨损试验在2t/h蒸汽锅炉(型号为DNS2-1.0-SM)上进1.1喷嘴材料及试样制备行冲蚀试验喷嘴内孔直径4.5mm,长15mm.水煤以乙醇作为介质,将AO3粉末(该粉末密度为浆消耗量200kg/h,供浆压力0.2MPa,雾化气压力表1水煤浆喷嘴材料的组成和性能Table 1sition and mDensity/gcm-1 Flexural strength/MPa Fracture toughness/MPa.m/2 Hardness/GPaI Cr18Ni9Ti75550(tensile strength)HB180~25011~1514.8Al O3/45%(W, Ti)C0.35~0.4MPa,炉膛最高温度1300℃,水煤浆浓蚀率),以单位质量的水煤浆所引起的喷嘴体积流失度65±2%发热量为18.81~20.48MJ/kg、粘度为来表征冲蚀率W,W=m:/(d·m2)(其中m1为喷嘴1000~2500mPa,s、粒度40~120-m的冲蚀磨损质量损失,d为喷嘴材料的密度,m2为燃采用万分之一电子天平称量冲蚀前后喷嘴的冲用水煤浆的质量)采用扫描电子显微镜(SEM)观察蚀磨损质量损失进而确定冲蚀磨损率(以下简称冲分析喷嘴冲蚀磨损表面的形貌基金项目,国家自然科学基金资助项目(50275088)收稿日期:2002125修回日期:20030401/联系人邓建新,e-mail:jxdeng@sdu,edu.cn作者简介邓建新,男,1966年生,博士教授博导目前主要从事切削加工及可掌性陶瓷材料摩擦学及陶瓷刀具开发等研究摩擦学学报第23卷YG8等3种喷嘴的冲蚀率随时间变化的关系曲线.可2结果与讨论见,3种喷嘴的冲蚀率均随冲蚀时间的增加而迅速增图1示出了1Cr18Ni9Ti、AlO3/(W,TiC和大,当冲蚀试验时间达到8h以后趋冲蚀率的变化244872120Erusinn time / at(a)1Cr18Ni9Ti nozzle(b)YG8 and Al O,/(W, Ti)C nozzlesFig 1 Variation of CWS nozzle erosion rates with the operation time图1水煤浆喷嘴冲蚀率随时间的变化于平稳.这主要是由于在磨损过程进入稳定阶段之前率较高,而高硬度陶瓷和硬质合金材料在相同条件下存在明显的快速磨损阶段,在该阶段冲蚀磨损率受到的冲蚀率很小.因此,高硬度的Al2O3/W,T)C表面平整度及表层材料在冲击载荷作用下发生调整和YG8喷嘴的冲蚀率很小,而低硬度的1Cr8Ni9Ti等多种因素的显著影响水煤浆对喷嘴的冲蚀属于低喷嘴的冲蚀率很大.角度冲蚀,低硬度的韧性材料在低角度冲蚀下的冲蚀图2为1Cr18Ni9Ti、Al2O3/(W,Ti)C和YG8等(a)1Crl8Ni9Ti nozzleCb)yG8 nozzle(c) Al,O,/(W, Ti)C nozzleFig 2 Optical photos of exit bore surfaces of the eroded nozzles图2水煤浆喷嘴出口冲蚀磨损表面形貌金相照片3种喷嘴出口冲蚀磨损表面形貌金相照片,可见,比1Cr8Ni9Ti更硬的大量矿物质,其在喷嘴内壁产1Crl8Ni9Ti喷嘴冲蚀后孔径显著增大,而YG8和生犁削作用,从而使喷嘴内壁表面形成大量犁沟.因Al2O3/(W,Ti)C喷嘴冲蚀后的孔径变化很小,但此,可以认为1Cr18N9Ti不锈钢喷嘴的冲蚀磨损机Al2O3/(W,Ti)C喷嘴出口处出现了明显的剥落现理主要表现为微观切削象.由于在燃烧过程中水煤浆喷嘴内部存在髙温度梯由图3(b)可见,YG8硬质合金喷嘴磨损表面存度和热应力,而陶瓷材料的抗热冲击性能远不如金属在许多凹坑这是由于YG8中含有熔点较低的金属材料,因此,陶瓷喷嘴出口处的剥落现象主要归因于粘结相Co,在水煤浆燃烧高温作用下,粘结相Co变喷嘴内部较大的热应力这同图1所示的陶瓷喷嘴在软,很容易被煤粉中的硬质颗粒冲蚀掉,从而在冲蚀初始阶段较大的冲蚀率相一致磨损表面留下大量空洞凹坑以及凸起的wC颗粒图3示出了3种喷嘴内壁冲蚀磨损表面形貌从AloO3/(W,Ti)C陶瓷喷嘴内壁磨损表面SEM照片.可见1Cr18NiTi不锈钢喷嘴磨损表面存SEM形貌照片可见,喷嘴磨损表面非常光滑,其晶相在大量犁沟和沟槽[图3(a)].这是由于煤粉中含有组织分布清晰可见[图3(c)].电子探针分析结果表第5期丁泽良等:水煤浆喷嘴热冲蚀磨损机理硏究4413决efie (akv. 25:5tk 1626(a) ICr18N9Ti nozzle(b)YG8 nozzle(c)Al, O,/(W, Ti)C ceramic nozzleFig 3 SEM micrograph of the worn bore surface of nozzles图3唢唏内壁磨损表面形貌SEM照片明图中白色部分为(W,Ti)C,黑色部分为Al2O3由[2] Deng Jian-xin, Feng Yi-hua, Ding Ze.Liang, Wear behavior of于AI1O3/(W,T)C陶瓷材料熔点及硬度远比水煤浆ceramic nozzles in sand blasting treatment [J]. Journal of the屮硬质煤粉颗粒的高因而表现出很强的抗低角冲蚀European Ceramic Socicty, 2003, 23(2): 323-3293] Ji Gang-cheng(纪岗吕), L i Chang-j(李长久), Wang Yu能力,此时水煤浆的冲蚀作用近似于煤粉中的硬质颗yue(王豫跃). Effect of spray conditions on erosion粒对陶瓷喷嘴内壁表面的硏磨作用,从而形成出非常performance of high velocity axygen fuel sprayed CriC2-NiCr光滑的冲蚀磨损表面coatings(喷涂工艺条件对超音速火焰喷涂CrC:NCr涂层冲logy(岸擦学学报),202,223结论a.材料硬度对水煤浆喷嘴的热冲蚀磨损行为[4 Ding Ze-liang, Deng Jian- xin, Li Jian-feng. Wear behavior ofceramic nozzles in abrasive jet machining [C]. The 6th具有显著影响在相同的试验条件下,具有高硬度的International Conference on Progress of Machine TechnologyAl2O3/(W,Ti)C陶瓷喷嘴的冲蚀率最小,YG8硬质Xi'’an,2002.385-390.合金次之,硬度较低的1Cr18N9T不锈钢喷嘴的冲5] Reshetnyak H, Kuybarsep. Mechanical properties of hard损率最大etals and their erosive wear resistance [J]. Wear, 1994.b.在高温低角度水煤浆冲蚀磨损条件下,[61 Xue Qun-ji(薛群基),1iu Hui-wen(刘惠文). Tribology oflCr]8Ni9Ti不锈钢喷嘴主要呈现微观切削特征,Ceramics I, Frietion and wear of ceramies(陶瓷摩擦学1.陶YG8硬质合金喷嘴主要呈现晶粒脱落特征,而瓷的摩擦磨损)[]. Tribology(摩擦学学报),1995,15(4)Al2O3/(W,TiC陶瓷喷嘴主要呈现热崩和硏磨损伤376-384特征[7] Sun Jia-shu(孙家枢), Wang Xiao-tong《王小同), Guo De-zhan(郭大展). Impact erosion wear behaviour and参考文献mathematic model of plasma spray ceramic coating by solidparticles(几种等离子喷涂陶瓷涂层之间固体粒子冲蚀磨损的[1] Ding Ze-liang(丁泽良), Li Jian-feng(李剑峰), Deng jian-xin持性与数学模型)[J. Tribology《摩擦学学报),199,14(邓建新). Study on application of coal water slurry nozzles(1):57-54.eral(水煤浆喷嘴材料的应用研究)J]. Coal PrcparationTechnology(选煤技术),2002,(6):13-15444摩擦学学报第23卷Thermal erosion Wear Behavior of Nozzles in CoalWater Slurry burningING Ze-liang 2, LI Jian-feng, DENG Jian-xin, AI Xing, ZHANG De-wei(1. School of Mechanical Engineering, Shandong University, Jinan 250061, ChinaZhuzhou Coal Preparation Plant, Zhuzhou 412005, ChinAbstract: Al,O,/(W, Ti)C ceramic composite was prepared by hot pressing technique. Then the nozzles usedin the coal water slurry burning were made from the resulting ceramic composite and 1Cr18Ni9Ti stainlesssteel and YG8 cemented carbide. The erosion behaviors of the nozzles in the coal water slurry buring wereted on a dnS -1. 0-SMboiler, at a coalof 200 kg/h andconcentration of (65+2)%, a slurry-feeding pressure of 0. 2 MPa, pulverized gas pressure of 0. 35-0. 4MPa, andemperature of 1 300 C. The eroded bore surface morphologies of the nozzlescroscope. Results showed that the hardness of the nozzles playedimportant role in determining the erosion-resistance in the coal water slurry(CwS)burning. The Al,O3W, Ti)C nozzles with high hardness exhibited lower erosion rates, while the 1Cr18Ni9Ti stainless steelnozzles with low hardness showed higher erosion rates under the same test conditions. The nozzle made from1Cr18Ni9Ti stainless steel was dominated by plowing and micro-cutting, that made from YG 8 cementedcarbide was characterized by grain peeling off, and the one made from the Al2O, /(w, Ti)C ceramic compositewas dominated by thermal shock and grindeyi nozZle i erosionAuthor:DENGJian-xin,male,bornin1966,Ph.D,Professor,e-mail:ixdeng@sdu.edu.cn.