【作者】 傅斌友；

【导师】 李晓延； 贺定勇；

【作者基本信息】 北京工业大学 ， 材料加工工程， 2009， 博士

【摘要】 本文从非晶合金成分设计和喷涂工艺参数优化两方面出发,研究了喷涂过程中合金元素对Fe-(Cr, Ni)-(C, B)合金系非晶形成能力的影响机制及规律;在优化工艺参数条件下制备了不同非晶含量的Fe基非晶合金涂层,建立了非晶相含量与涂层微结构特征的影响关系,并研究了非晶合金涂层的摩擦磨损与磨粒磨损行为及其相应的磨损机理。探讨了不同退火温度下Fe基非晶合金涂层微结构的演化机制,及其对涂层组织及性能的影响。主要研究结果如下:采用电弧喷涂方法制备非晶涂层,涂层中非晶含量最高可达65.3%。涂层的最佳喷涂工艺参数为:喷涂电流180A,喷涂电压32V,压缩空气压力0.55MPa,喷涂距离100mm。在优化喷涂工艺参数条件下制备了不同非晶相含量的Fe基非晶涂层,涂层由变形良好的扁平化粒子相互搭接堆积而成,呈典型的层状结构形貌,通过图像分析软件测量涂层孔隙率在1.80-2.75%范围内。制备的非晶涂层显微硬度超过1100 HV0.1,结合强度可达69MPa,高于常见材料电弧喷涂涂层的结合强度(30-50 MPa)。涂层耐磨粒磨损性能约为Q235钢的15倍以上,主要磨损机制为涂层脆性断裂和硬质相脆性剥落;涂层摩擦磨损过程中保持较低的摩擦系数,随非晶含量的提高摩擦系数逐渐减小,在经过3900米摩擦磨损测试后,其磨损量仅为Q235钢的5.2%-10%,涂层的摩擦磨损机制主要以疲劳断裂为主。随涂层中非晶含量增加,涂层耐磨粒磨损与耐摩擦磨损性能增加。非晶涂层在400℃、500℃预热处理过程中,涂层中非晶相组织只发生结构驰豫,仍保持非晶合金的结构状态。在600℃热处理过程中涂层中非晶相完全晶化,晶化析出相主要为富Fe相和Fe23(C,B)6等硼化物硬质相。在700℃-900℃热处理时,保温4小时,涂层中晶化相晶粒缓慢长大,晶粒尺寸始终保持在纳米晶范围内。涂层在热处理过程中逐步致密化,孔隙率降低。涂层在非晶晶化前,随着热处理温度上升,显微硬度增加,耐磨粒磨损和摩擦磨损性能缓慢下降;热处理温度达到600℃时,涂层完全晶化,之后随着热处理温度的上升,涂层显微硬度缓慢下降,耐磨粒磨损和摩擦磨损性能趋于稳定。更多还原

【Abstract】 The effect of alloy components on the Fe-(Cr,Ni)-(C,B) amorphous alloy’s glass forming capability during arc spraying process was invistigated based on the design amorphous alloy system and parameters optimization of coating process. The Fe-based amorphous alloy coatings with different content of amorphous phase were prepared by arc spraying using the optimized process parameters. The relationship between amorphous content and microstructure of the coatings was established, the tribology and abrasive wear behavior of the amorphous alloy coatings were studied in detail. Furthermore, the microstructures evolution and the wear performance of the amorphous alloy coatings during annealed at different temperatures was discussed. The major results are summarized as follows:The amorphous coatings were prepared by arc spraying technology, the highest amorphous content attainable 65.3%. The optimization arc spraying parameters are: current: 180A; voltage: 32V; air pressure: 0.55MPa; distance: 100mm. Fe-based coatings with different amorphous content were prepared by arc spraying technology under the optimization processing parameters, The coating consists of numerous flattened lamellae parallel to the substrate. The porosity is measured by the image analysis software and the value is between 1.80-2.75% scopes.The microhardness value of the amorphous coatings is more than 1100 HV0.1, and the highest bonding strength reached 69MPa. The coatings abrasive wear resistance are more than 15 times higher than that of the Q235 mild steel, the main wear mechanism were the lamellae brittle fracture and the hard phases brittle spalling. All the coatings were maintain low friction coefficient in the frictional wear process, and the friction coefficient reduced with the increasing amorphous phase content. The mass loss of the coatings were 5.2%-10% of the Q235 steel after 3900 m friction wear test, the main wear mechanism were the lamellae fatigue fracture. The abrasive wear resistance and the ring-on-block wear resistance of the coatings improved with the amorphous content increasing in the coatings. The amorphous phase of the coatings merely occurred structural relaxation when annealed at 400℃and 500℃. The amorphous phase will complete crystallization after heat treatment at 600℃and the predominant crystalline phases precipitated were Fe rich phase and Fe23(C,B)6 hard phase. The crystal grains will gradual growth while the coating heat treated at temperature between 700-900℃, the grains size while remain at the nanocrystalline range. The coating’s particle interface will fusing, microstructure compacting and porosity decreasing in the heat treatment process. The microhardness increasing and wear resistance decreasing when the heat treatment temperature increased before the amorphous phase complete crystallization; and then the coating’s microhardness decreasing and the wear resistence keep stable.更多还原