【作者】 董艳春；

【导师】 阎殿然；

【作者基本信息】 河北工业大学 ， 材料学， 2006， 博士

【摘要】 本文主要研究了用微米级的Ti粉,通过反应等离子喷涂的方法制备纳米晶的TiN涂层材料。设计了反应室并研究了制备TiN涂层的工艺;表征了涂层的物相组成,显微结构;讨论了纳米TiN涂层形成的机理;分析了涂层的力学性能、摩擦磨损性能、耐腐蚀性能和热处理对涂层组织及性能的影响。获得了一些有价值的结果。设计制造了出四代反应室,并用带反应室的喷枪和XX-XX型喷枪喷涂微米级Ti粉成功制备了纳米晶TiN涂层,用正交实验的方法优化了制备TiN涂层的工艺参数。表征了涂层的微观结构,采用SEM、TEM、HRTEM观察及由XRD谱线计算发现:TiN涂层是由晶相和非晶相构成,晶相主要是TiN相及少量的Ti3O;晶相的亚结构是由相互平行的纳米棒构成的捆在空间随机堆垛而成,纳米棒的直径为70-100nm;涂层的晶相含有大量生长孪晶;对反应室内沉积的TiN进行TEM观察,发现有位错运动及相互作用的现象。研究了涂层的力学性能,发现TiN涂层有较高的硬度及断裂韧性,其横截面的平均硬度为1720HV100g;纵截面的平均硬度为1260HV100g;横截面的KIC=7.065MPam1/2,纵截面的KIC=4.915MPam1/2;涂层具有明显的压痕尺寸效应;经分析压痕、摩擦表面及压痕尺寸效应发现,TiN材料受力后有明显的变形及加工硬化现象。研究了涂层的耐磨性和耐蚀性,发现在无润滑磨损条件下,纳米TiN涂层的耐磨性能比淬火M2钢好,其摩擦系数为0.40,其主要磨损失效形式是涂层的剥落;在稀HCl、H2SO4及NaCl溶液中TiN涂层本身表现出极高的耐蚀性,带TiN涂层的钢铁材料在0.5mol/L的HCl溶液致钝电流低于18-8不锈钢,而击破电位高于不锈钢。研究了1000℃退火处理对TiN涂层组织和性能的影响,发现退火后TiN涂层的晶粒并未长大,涂层的致密度提高,韧性改善、摩擦系数降低,体现了TiN自润滑的特性。理论上研究了反应等离子喷涂形成纳米TiN涂层的动力学,实验发现Ti-N2燃烧合成是形成纳米晶的必要条件,而等离子喷涂及快冷是形成纳米晶的充分条件,Ti-N2燃烧合成的反应使反应产物完全熔化,而等离子喷涂使液滴瞬间在基体上激冷,从而形成非晶及纳米晶。更多还原

【Abstract】 The nano-crystalline titanium nitride coating material was prepared by reactive plasma spraying (RPS) micron-Ti powders in this paper. The gas-tunnel type reaction chamber was designed, and parameters of spraying TiN coatings were majorized. The phases, microstructure of the TiN coating were analyzed by XRD, SEM, TEM and HRTEM, and formation mechanism of the TiN coating was discussed. The mechanical property, wear and friction property, and corrosion resistance were investigated. Microstructure and property of the coating after treatment were analyzed, too. The research conclusions as follow were obtained:Four generation reaction chambers was designed and fabricated, and nano-crystalline TiN coatings were fabricated via spraying Ti powders using the special spraying gun composing the self-designed gas-tunnel type reaction chamber with general plasma spray gun and XX-XX type spraying gun.The microstructure of TiN coating was characterized. Through observing using SEM, TEM, HRTEM and calculating using Scherrer formula, it was found that TiN coatings are composed of nano-scaled crystal grains of TiN,a little Ti3O and non-crystal. The substructure of crystal phase is that the bundles, which are made of nano-bars, random stack in space. The nano-bars, whose diameter range is from 70 to 100 nm, are parallel each other. Many growth twins were observed in the TiN coating. The phenomenon of movability dislocations sliping and interacting were found in TiN which deposit in reaction chamber.The mechanics properties of TiN coating were studied. It was found that the TiN coating present higher micro-hardness and fracture toughness. The average hardness and KIC of cross-section of the TiN coating is 1720HV100g and 7.065MPam1/2; respectively, and those of the longitudinal section of TiN coatings were 1260 HV100g and 4.915 MPam1/2. The TiN coating presents apparent indentation size effect. The phenomenon of work-hardening and deformation was found in TiN coating materials via observing indentation and friction surface and indentation size effect.The wear and corrosion resistance of TiN coatings were investigated. The wear resistance of the TiN coating is better than that of quenched M2 steel under dry friction and wear condition. The friction coefficient between TiN coating and GCr15 is 0.4, and the invalidation mode of the TiN coating is coatings scaling. TiN coatings present good corrosion resistance. The passivation current of steel coated with TiN coating is smaller than 18-8 stainless steel in 0.5mol/L HCl solution, but destroy potential is higher than stainless steel.The microstructure and property of TiN after annealing at 1000℃were discussed. It was found that the density of the TiN coating enhanced, toughness was improved and the friction coefficient decreased, which reflect the self-lubrication character of the TiN coating, through 1000℃annealing under nitrogen shield.The formation dynamics of nano-crystalline TiN coating was analyzed. It is found that, for reactive plasma spraying nano-TiN coatings, combustion synthesis between Ti and N is the necessary condition, and plasma spraying and shock cooling is the sufficient condition. Combustion synthesis reaction melts the reaction products, and refines TiN liquid drops. TiN liquid drops shock-cooling under the plasma spraying condition, solidify and form nano-crystal TiN coating on substrates.更多还原