【作者】 李方坡；

【导师】 王引真；

【作者基本信息】 中国石油大学 ， 材料学， 2008， 硕士

【摘要】 本文以Ti-B₄C-C-Ni为原料,采用反应超音速火焰喷涂技术,制备TiC-TiB₂-Ni涂层,并对涂层合成机理、组织及相关性能进行研究。热力学计算分析表明,自蔓延高温合成TiC-TiB₂-Ni金属陶瓷过程中的绝热燃烧温度随Ni含量的增加而降低,随预热温度的升高而升高。反应超音速火焰喷涂TiC-TiB₂-Ni涂层中除含TiC、TiB₂、Ni相外,还含有一定量的Ti（C、N）、TiO₂、Ti₂O₃和NiO相。喷涂粒子经历孕育、飞行反应、碰撞沉积等阶段后形成涂层,涂层呈典型的层状结构。当TiC/TiB₂比例为1/2时,随Ni含量的增加,涂层组织均匀性增强,夹杂减少,显微硬度降低,结合强度和耐滑动磨损性能呈先升高后降低的变化趋势。Ti-B₄C之间的反应趋势明显大于Ti-C之间的反应趋势。当Ni含量为40%时,随着TiC/TiB₂比例的增加,涂层组织中的夹杂增多,显微硬度和结合强度逐渐降低,涂层耐滑动磨损性能下降。TiB₂引入到TiC涂层中可以显著提高涂层的力学性能。Ni含量和TiC/TiB₂比例的相互作用对涂层性能影响并不显著。当Ni含量为40%,TiC/TiB₂比例为1/2时,涂层的滑动磨损量和冲蚀磨损量均为最小,分别为16.5㎎和76.9㎎。涂层的滑动磨损失效形式主要表现为犁削和脆性剥落。TiC-TiB₂增强NiCrBSi涂层的耐滑动磨损性能明显优于NiCrBSi涂层,而略低于NiCr-Cr₃C₂涂层,涂层组织中出现了明显的金属相与陶瓷相的偏聚现象,均匀性略低于TiC-2TiB₂-40%Ni涂层。冲蚀角度对涂层的耐冲蚀磨损性能有较大影响,在75°角冲蚀作用时,TiC-TiB₂增强NiCrBSi涂层的耐冲蚀磨损性能略低于NiCrBSi涂层和NiCr-Cr₃C₂涂层;而在30°角冲蚀作用时,TiC-TiB₂增强NiCrBSi涂层的耐冲蚀磨损性能优于NiCrBSi涂层。更多还原

【Abstract】 TiC-TiB₂-Ni coatings were successfully sprayed on the steel substrate with Reactive High Velocity Oxygen Fuel spraying and Ti-B4C-C-Ni reactive system.The reactive principle, microstructure and properties of TiC-TiB₂-Ni coatings’were researched. The analysis of ther- -modynamics of TiC-TiB₂-Ni utilizing the self-propagating high-temperature synthesis reaction of Ti-B4C-C-Ni system shows that adiabatic temperature decreases with the increase of nickel content, and increases with the increase of preheating temperature. Reactive High Velocity Oxygen Fuel spraying TiC-TiB₂-Ni coatings are composed of the major phases of TiC, TiB, Ni, some of Ti（C、N）, Ti2O3, TiO2 and NiO. Laminate structure coating was formed after spraying particles experiencing stages of pregnant, flight reaction and colliding.On the condition that TiC/TiB₂ molar ratio is 1/2, TiC-TiB₂-Ni matrix coatings’porosity, lard and micro-hardness decrease gradually with the increase of nickel content. However, their binding strength and wear resistance rise at first and then fall with the increase of nickel content. The reaction of Ti-B4C system is more likely to occur than that of Ti-C system. As nickel content is 40%, coatings’micro-hardness, binding strength and wear resistance decrease with the increase of TiC/TiB₂ ratio. Therefore, the introduction of TiB₂ ceramic phase can significantly improve coatings’mechanical properties. The interaction of nickel content and TiC/TiB₂ molar ratio has a little effect on TiC-TiB₂-Ni coatings’mechanical properties. On the condition that nickel content is 40% and TiC/TiB₂ molar ratio is 1/2, coating’s drying sliding wear weight and erosive loss are the lest of all, which are 16.5㎎ and 76.9㎎ separately. In addition, the drying sliding wear mechanism of coatings’is characterized by ploughing and spalling.TiC-TiB₂ ceramics improves NiCrBSi coating’s wear resistance effectively.There is partial phenomenon between metal and ceramics phases in TiC-TiB₂ reinforced NiCrBSi coating, which decreases coating’s uniformity. Impinging angle has great effect on coatings’erosive wear resistence.At 75°jet angle, erosive wear resistence of TiC-TiB₂ reinforced NiCrBSi coating is worse than those NiCrBSi coating’s and NiCr-Cr₃C₂ coating’s. However, at 30°jet angle, its erosive wear resistence is better than that of NiCrBSi coating’s significantly.更多还原