【作者】 刘少光；

【导师】 李志章；

【作者基本信息】 浙江大学 ， 材料加工工程， 2006， 博士

【摘要】 针对国内外火力发电厂燃煤锅炉管道（水冷壁、过热器、再热器、省煤器管）存在着的严重高温冲蚀磨损现象以及由此造成的重大经济损失的现实问题，本博士课题从研究方法的可行性和研究成果的应用价值出发，采用最切合实际的超音速电弧喷涂技术作为基础，全方位、创新性地对喷涂用材料的制造设备、电弧喷涂设备、电弧喷涂工艺、电弧喷涂材料以及涂层性能的试验研究设备进行全面的深入研究，发扬了电弧喷涂技术的优点，弥补了电弧喷涂技术的不足，将电弧喷涂技术、设备、工艺、材料及涂层性能提高到一个崭新的水平，具有很大的实际应用价值和重要的学术意义，经现场使用已产生很好的使用效果和经济效益。首次研究、设计、制造电弧喷涂粉芯丝材的专用设备：轧拔式叠口包丝机（CWCM05）和张力式直线拉丝机（CWDM05）。该专用设备的成功研制为本博士课题的顺利进行提供了基本保障，不仅可用于研究涂层的成分、喷涂工艺、组织结构与性能之间的关系，而且可用来研究开发更多新型的喷涂材料和新的电弧喷涂层。用CWCM05和CWDM05制成的成品丝材表观质量好，表面光洁度、光滑度、圆整度较高，叠口搭接情况良好，包粉密实，经电弧喷涂检验，走丝流畅，行弧平衡，无爆枪现象发生。该专用设备年生产能力近500吨／年。已获得发明专利（发明专利权号：ZL200410017882.9）。首次提出用N₂保护的方法控制喷涂材料的氧化问题，并研究制造适合于超音速电弧喷涂的N₂保护装置。在电弧喷涂技术中引入N₂保护将对涂层性能的提高、应用价值的提升和电弧喷涂技术的发展产生重要的影响。另外，对电弧喷枪进行改造，在枪管（喷管）上安装Laval腔体使气流被加速到超音速，从而提高喷涂熔滴的速度，为后续的涂层组织结构和性能研究提供必要的设备保证。当雾化气压为1MPa时，喷涂熔滴的速度可达515m／s超高音速。发明新型复合式导电嘴，它具有良好的导电性和耐磨性，行弧平衡，无爆枪现象，工作效率大为提高。使用寿命从2～4小时提高到近3000小时，维修时间减少90％以上，生产率提高40％左右，经济效益将非常显著。已获得发明专利和实用新型专利（发明专利权号：ZL200410017883.3，实用新型专利权号：ZL200420022150.4）。首次研制出模拟燃煤锅炉管道工况条件的专用高温冲蚀磨损试验设备：增压式分段加热高温冲蚀试验机（HTEA-04）。HTEA-04高温冲蚀试验机具有以下特点：冲蚀气流（冲蚀磨粒）速度稳定、可调；冲蚀气流温度控制准确，可在300～1100℃范围随意设定；增压式加料器加料速度、均匀性、流畅性好，可用于各种类型、粒度、比重的磨粒；试样的温度可在200～600℃范围任意设定；利用分段加热方式，可以大大简化复杂的试样冷却系统；试样装卸方便，试验周期较短，显著提高试验效率，降低试验成本；该试验机结构简单，制造成本较低，维护方便。已申报专利。系统地利用自行研究、设计、制造的粉芯丝材制造设备（CWCM05、CWDM05），改进的超音速电弧喷涂设备（CAS-400），研制的高温冲蚀试验设备（HTEA-04）进行无N₂保护和有N₂保护的工艺参数研究。首次以（56％Cr₃C₂+30％Cr+6％V-Fe+4％Nb-Fe+4％Mn）芯粉材料的粉芯丝材CW-T为涂层材料，通过改变喷涂速度对涂层的组织结构、孔隙率、结合面互扩散、硬度、结合强度、内聚强度、抗氧化性和高温冲蚀性能进行研究，并通过试验对比，研究N₂保护的作用。选取切实可行的最佳工艺参数（雾化气压0.8MPa，喷涂熔滴速度393m／s）用于后续的材料研究。已申报专利。利用粉芯丝材的特点，首次对Ti-Al金属间化合物复合材料超音速电弧喷涂层组织结构及高温冲蚀性能进行研究。所开发的粉芯丝材抗高温磨蚀的性能由强到弱依次为ACW1、ACW4、ACW2、ACW3。经过喷涂工艺优化，Ti-Al系列金属间化合物复合材料可望作为优秀的抗高温冲蚀涂层材料。电弧喷涂层的结构表现为“叠层”特征，“凝片”间存在由于喷涂过程中芯粉材料和表皮材料氧化导致的氧化物。本试验中，4类喷涂层在0.15～0.18mm Al₂O₃磨粒的高温冲蚀试验条件下，表现出来的高温冲蚀磨损机理主要有脆断、疲劳剥落、切削和犁耕。研究了Ti-Al及Cr系金属间化合物电弧喷涂层超临界冲蚀规律。发现BCW1、BCW2涂层具有固溶体相和氧化物相相互间隔的叠层结构特点。氧化物以Fe₃O₄形式存在。800℃、150小时氧化增重试验结果表明，BCW1和BCW2涂层的抗氧化性能分别是20钢的10倍和15倍。20钢的最大冲蚀率在15°附近，而BCW1和BCW2涂层的最大冲蚀率在45°附近。不论是高冲击角还是低冲击角，BCW1、BCW2涂层的耐冲蚀性能都明显优于20钢。冲击角为45°时，BCW1和BCW2涂层的耐冲蚀性分别是20钢的3.1和3.0倍。研究了N₂保护对TiAl₃和Cr₃C₂复合材料超音速电弧喷涂层组织结构及高温冲蚀性能的影响。研究发现，在N₂保护下的电弧喷涂层比无保护时的涂层更为致密和均匀，氧化夹杂物明显减少，硬度显著提高。本实验条件下，凝片与凝片的分离，以及凝片的断裂、掀起和剥落是产生冲蚀磨损的主要原因。而氧化夹杂物明显降低凝片与凝片间的结合力，从而降低涂层抗高温冲蚀性能。氮气保护的CCW1、CCW2、CCW3电弧喷涂层的平均体积冲蚀率比无氮气保护的分别降低3.3倍、2.3倍和1.0倍。研究了时效对含纳米复合材料超音速电弧喷涂层组织结构及高温冲蚀性能的影响。采用含纳米粉复合粉芯丝材进行电弧喷涂时，丝材的表皮材料和芯粉材料能相互熔解和融合形成较均匀的固溶体。研究发现：时效处理使涂层中各组成相晶格缺陷减少，应力消除，结晶度提高，同时亚稳相分解，孔洞等缺陷减少，从而显著提高涂层硬度，并使涂层中硬度分布更均匀。时效处理未明显提高DCW3涂层的抗高温冲蚀性能，但显著提高含纳米组分的DCW1、DCW2涂层的耐高温冲蚀性能，提高幅度分别为20％和29％。首次研究了N₂保护对含纳米复合材料超音速电弧喷涂层组织结构及高温冲蚀性能的影响。N₂保护提高涂层的致密性和均匀性，组织的连续性得到明显改善，涂层中氧化物显著减少。N₂保护使更多的合金元素熔入Fe中形成Fe基固溶体。透射电镜分析表明，纳米陶瓷相在基体相中呈较均匀的弥散分布状态。涂层中的氧化物是影响冲蚀抗力的主要因素之一。N₂保护的涂层受磨粒冲蚀时，不会出现明显的层状形式流失，所以冲蚀率显著降低。ECW1、ECW2、ECW3的氮气保护下涂层平均体积冲蚀率比无氮气保护的分别降低3.4、6.4和6.5倍。氮气保护显著减少纳米组分的烧损，改善纳米陶瓷相与基体相的结合，更充分发挥纳米组分对涂层的弥散强化作用。已获得发明专利（发明专利号：ZL200410017882.9）。更多还原

【Abstract】 Supersonic arc spray technology was used as the most practicable method and manufacturing equipment of spraying material, arc spray machine, spraying technique, arc spray materials and testing apparatus for the coatings were investigated comprehensively, thoroughly and innovatively in this paper proceed form feasibility of investigation method and application value of investigation achievement, according to actual problem that there were serious high temperature erosion phenomenon and enormous economical losses caused on the boiler tubes of coal-fired power plants at home and abroad. The advantages of arc spray technology were developed and its’ defects were overcome in the investigation. The arc spray technology, equipment, technique, spraying materials and coatings’ properties were developed to a completely new level after the research, and then there are very good actual use value and important scientific significance. Quite good applied effect and economic benefit are proved after on-the-spot application.The special equipments for manufacturing arc spray cored wire: drawing-rolling style overlapping cored wire covering machine （CWCM05） and tension style cored wire drawing machine CWDM05) were investigated, designed and manufactured for the first time. Successful manufacture of the equipments provided basic guarantee for the doctor project. They can be used not only for investigation of coatings’ composition, spray technology, structure and properties, but also for development of much new kinds of spraying materials and new arc spray coatings. The cored wires manufactured by CWCM05 and CWDM05 have good apparent mass, fineness, smooth, roundness, overlapping and powder cored consistency. Test by arc spraying performed that the cored wire went smoothly, arc sprayed stably and there was no detonation phenomenon. The special equipments can manufacture cored wires 500 tons per year approximately. We have gained invention patent right （Invention patent number: ZL200410017882.9）.N₂ protective atmosphere was put forward for controlling oxidation of arc-sprayed materials, and then N₂ protective device used for supersonic arc spray wason microstructure, porosity, inter-diffusion of interface, hardness, bond strength, cohesive force, oxidation resistance and high temperature erosion resistance was investigated by using the cored wire containing composite cored powder （56%Cr₃C₂+30%Cr+6%V-Fe+4%Nb-Fe+4%Mn） as the coating material. Effect of N₂ protection was also investigated by testing comparison. At last, the best technological parameters of arc spray that was feasible for application was selected for following investigations of spraying materials. We have also applied for patent.Microstructures and high temperature erosion of arc spray coatings of Ti-Al intermetallics composite materials were investigated by using the feature of cored wire for the first time. High temperature erosion resistance of the coatings of developed cored wires decreased in the order of ACW1>ACW4≥ACW2>ACW3. By optimization of spraying process factors, Ti-Al intermetallics composite materials will be able to use as excellent coating material of anti-high temperature erosion. The arc spraying coatings exhibited typical "lamination" microstructure. The oxides located between "splat" were caused by oxidation of both the cored powders and the iron sheaths. Erosion mechanisms of the spraying coatings under the present testing conditions included brittle breaking, fatigue spalling, cutting and ploughing.Supercritical erosion regularity of arc spraying coatings of Ti-Al and Cr intermetallics composite materials was investigated. The "lamination" microstructure feature that solid solutions were laminated by oxides in the coatings of BCW1 and BCW2 was discovered. Oxide existed in the form of Fe₃O₄. The result of 800℃ 、 150h oxidation testing shows that oxidation resistances of BCW1and BCW2 coatings were 10 and 15 times of that of 20 carbon steel respectively. The highest erosive rate of 20 carbon steel occurred near 15 degree, but that of BCW1 and BCW2 coatings appeared near 45 degree. Whether or not impinging angle was high （or low）, erosion resistance of BCW1 and BCW2 coatings was obviously higher than that of 20 carbon steel. Erosion resistances of BCW1 and BCW2 coatings were 3.1 and 3.0 times of that of 20 carbon steel respectively.Influence of N₂ protective atmosphere on microstructures and high temperature erosion of TiAl₃ and Cr₃C₂ composite material coatings by supersonic arc spray wasinvestigated. It was discovered that the coating arc-sprayed under N₂ protective atmosphere had denser and more homogeneous structure, fewer oxide inclusion and higher hardness than under air atmosphere. In this testing condition, separation between splats and fracture, surging and spalling of splat was the main reason of erosion wear. Oxide inclusions reduced obviously cohesive force between splats, therefore decreased high temperature erosion resistance of the coating. The volume erosive rates of CCW1、 CCW2 and CCW3 coatings arc-sprayed under N₂ protective atmosphere decreased by 3.3, 2.3 and 1.0 times as that under air atmosphere.Influence of age on microstructures and high temperature erosion of composite material coatings containing nanosized ceramics by supersonic arc spray was investigated. The cored powders and the iron sheaths could form homogeneous solid solution by fusing and mixing in the process of arc spraying composite materials containing nanosized ceramics. It was discovered that age reduced defects of crystal lattice, removed concentrated stress, increased crystallization content, decreased hole and cavity, resolved instable phase, thus raised fairly hardness of the coating and made hardness distribute more homogeneously. Age did not increase high temperature erosion resistance of DCW3 coating, but increased that of DCW1 and DCW2 coatings by 20% and 29% respectively.Influence of N₂ protective atmosphere on microstructures and high temperature erosion of composite material coatings containing nanosized ceramics by supersonic arc spray was investigated for the first time. N₂ protective atmosphere could raise density and homogeny of coatings, improve continuity and reduce oxides of coatings very much. N₂ protective atmosphere also made more alloy elements fuse and mix into iron to form iron-based solid solution. Analysis by TEM （transmission electron microscope） shows that nanosized ceramics phase was distributed in the based solution in a form of dispersion. Oxides in the coatings were one of main facts that affected erosion resistance. The coatings sprayed nuder N₂ protective atmosphere did not occur obviously in the form of lamination of material loss when eroded by erosive abrasives, so the erosive rates were quite low. The volume erosive rates of ECW1、 ECW2 and ECW3 coatings arc-sprayed under N₂ protective atmosphere decreased by3.4, 6.4 and 6.5 times as that under air atmosphere. N₂ protective atmosphere reduced burning loss of nanosized ceramics very much, improved bonding of nanosized ceramics phase and base phase, and gave full play of nanosized ceramics to disperse hardening effect. We have gained invention patent right （Invention patent number: ZL200410017882.9）.更多还原