【作者】 杨洪刚；

【导师】 张松； 宋贵宏；

【作者基本信息】 沈阳工业大学 ， 材料学， 2005， 硕士

【摘要】 钛合金具有优良的常温性能,但高温下抗氧化性能和抗腐蚀性能不很理想。搪瓷属非晶结构,具有较强的抗氧化、抗腐蚀性能,涂敷在钛合金表面能够起到很好的保护效果。搪瓷的力学性能较差,稀土由于其特殊的电子结构及高熔点等特性近年来在搪瓷工业得到广泛应用。本文研究了稀土添加到搪瓷涂层中对其抗腐蚀,抗氧化性能,磨损性能,抗拉强度等力学性能的影响。 目前搪瓷釉料的预置主要有浸涂、喷涂等几种常规方法,其缺点是涂层厚度往往不够均匀,同时二者还受到基体形状的限制,尤其是对试样边角处理上,因此在使用中具有一定的局限性。针对上述方法存在的不足,我们提出了采用电泳沉积技术在Ti60合金表面预置搪瓷涂层。 本论文研究了一种适合于钛合金表面涂搪的电泳液配方,对影响电泳沉积涂层的各种因素进行了探讨,优化了电泳工艺参数,研究了电泳涂搪动力学规律及速度控制步骤,确定了电泳沉积预置搪瓷涂层的最佳工艺条件,研究了瓷釉粉微粒表面烧结工艺,并分析了电泳搪瓷涂层的组织形貌和相组成,同时比较了普通搪瓷涂层和稀土搪瓷涂层对合金抗高温氧化性能、耐高温腐蚀性能、磨损性能及抗拉强度的影响。 本论文研究表明,电泳搪瓷涂层的最佳工艺条件为:粉浆浓度为150-200g/L,电压为15-20V,沉积时间为3-5s,极间距为1.5-2.0cm,轻搅拌或不搅拌,在100℃真空条件下干燥1h。电泳后在850℃-900℃下烧结20-40min成型。 研究结果表明,涂层致密、厚度均匀,与基体结合良好,且搪瓷涂层与基体界面处不存在明显的元素互扩散。 Ti60合金在700℃下氧化后,表面形成一层明显的氧化层,且动力学曲线基本遵循抛物线规律,施加普通搪瓷和稀土搪瓷涂层后,由于涂层与基体合金相近的热膨胀系数及搪瓷较高的热稳定性,试样在高温下氧化后,涂层/合金界面仍然有很好的结合。 在700℃涂盐腐蚀和熔盐腐蚀条件下Ti60腐蚀动力学符合抛物线规律,施加普通搪瓷和稀土搪瓷涂层后,显著提高了Ti60合余的腐蚀性能,未见明显腐蚀,涂层/合金界面与涂层烧结时起始状态相比无显著变化。更多还原

【Abstract】 Although titanium alloy has excellent performance at normal temperature, the resistance to oxidation and erosion is not ideal. Because of the noncrystallic strcture, enamel has eminent property in these aspect ,so can protect alloy. Due to its special electronic structure and high melting point of RE(rare earth) has been applied widely in industry to improve the mechanical property of enamel recently years. These paper study the effect of RE on the wearing. quality and tensil strength when they are added to the enamel.Prefabricating enamel frit is mainly used such normal methods as dipping and spray coating. But, the thickness of the coating obtained is not uniform. Compared with porcelain dipping and spray coating, electrophoretic deposition (EPD) has great advantages. For example, there is no limitation in the shape of matrix and the thickness of coating is even.A kind of electrophoretic solution adapted to prefabricating enamel on Ti60 alloy was studied. The processing parameters were optimized. The various factors affected deposition qulity were discussed. The kinetics of EPD was investigated and the process of speed controlling EPD was determined. The optimal processing parameters of prefabricating enamel coating on titanium alloy by electrophoretic deposition were given.Sintering technique of enamel coating were studied. Microstructure and phase composition of enamel coating was observed .At the same time, the ordinary enamel coat and RE enamel coat were compared to study their character in oxidation, erosion, wearing and tensile strength.Research shows that the optimal processing parameters are as follows: The concentration of enamel-eletrophoretic solution is 150-200g/L, the voltage is 3-5V, thetime of EPD is 3-5s, the die opening is 1.5-2.5cm, sintering temperature is at 850°C - 900 °C and time is 20- 40min.The cross section morphology of the coating observed by SEM/EDX indicated that a tight bonding between the matrix and coating and a high density of film were obtained.There is an obvious oxide layer on the surface of Ti60 alloy after oxided at 700°C in air, and the oxidation kinetics of Ti60 alloy follows a parabolic curve. Enamel coating whether there was RE or not markedly improved the oxidation resistance of the alloy at 700 °C in air, since the coating possesses a good thermo-chemical stability and a thermal expansion coefficient matched with that of Ti60 alloy.The corrosion kinetics of Ti60 alloy follows parabolic curve in both condition of brushing salt and melting salt. Enamel coating has shown a good corrosion resistance whether there was RE or not.The ordinary enamel coat exihibit good abrasion resistance compared with metrix alloy. The wearing failure of enamel coat took on brittleness spalling character which originated from crack generated during slid. The added RE can ameliorate this situation.The high melting point of RE can nucleate early and so will control the diffusion of oxygen into metrix.From the tensil fracture morphology ,a narrower oxygen brittleness layer was observed.更多还原