【作者】 韩晓燕；

【导师】 陈旭；

【作者基本信息】 天津大学 ， 化工过程机械， 2007， 硕士

【摘要】 鉴于大多数金属构件会由于机械因素或其它物理因素以及周围环境的腐蚀因素等引起破坏,本文重点研究了一种耐高温防腐蚀涂层的疲劳性能。采用机械共混的方法配制了聚苯硫醚(PPS)悬浮液,并通过高温塑化工艺在金属表面制备了涂层,确定了合适的热处理工艺参数。对涂敷PPS涂层的Q235-A钢板试件在应力控制下进行了对称循环载荷疲劳试验,研究了材料的循环硬化软化特性。结果表明:对称循环载荷导致钢板发生了没有明显颈缩的断裂,对PPS涂层的影响不明显;Q235-A和PPS涂层在试验的初始阶段出现了快速的循环软化现象,经过了一定的循环周次后达到了循环稳定,加载应力水平越高,循环软化速率越大,达到循环稳定所需的循环周次也越小;Q235-A钢的曲线在双对数坐标系中为线性关系,遵循Basquin方程,疲劳寿命随应力幅值的减小而增加。本文还对涂敷PPS涂层的钢板试件进行了非对称循环载荷试验,研究了平均应力、应力幅值对材料棘轮应变的影响。结果表明:非对称循环载荷导致钢板表面的PPS涂层发生了失效,钢板没有发生明显的变化;在应力幅值恒定的条件下,随着平均应力的增加,棘轮应变增加,且循环饱和棘轮应变也增加;在平均应力恒定时,随着应力幅值的增加,棘轮应变增加,且循环饱和棘轮应变也增加,但应力幅值的影响不如平均应力的影响大。在应力幅值相等的条件下,平均应力-寿命曲线在双对数坐标系中为线性关系,疲劳寿命随平均应力的减小而延长;在平均应力相等时,应力幅值-寿命曲线在双对数坐标系中也为线性关系,疲劳寿命随应力幅值的减小而延长。更多还原

【Abstract】 Because most metal component are easily destroyed by mechanical, physical and corrosive condition, the mechanical fatigue performance for anti-corrosion and high-temperature coating is studied in the paper. Polyphenylenesulphide(PPS) suspension dope was prepared using the method of mechanical mixing, and the PPS coating was prepared in metal surface through the process of high-temperature plastication. The appropriate parameters for heat treatment were determined.The fatigue experiments under stress-controlled cycling were conducted on Q235-A steel sample with PPS coating on its surface. The cyclic harden and soften characteristic were studied. It is shown that the symmetrical cyclic loading resulted in rupture of steel without necking, and had no obvious effects on the PPS coating. A fast cyclic soften phenomena happened on the initial period of the experiment both for Q235-A and PPS coating, then achieved cyclic stability after certain cycles. The cyclic soften rate increase with the loading stress level increased, and the cycle to achieve cyclic stability decreased. The S ? N curve of steel was linear on the log-log coordinates, and fatigue life increase with the stress amplitude decreased.A series of ratcheting experiments were performed on Q235-A steel sample with PPS coating on its surface. The effects of mean stress and stress amplitude on ratcheting strain were studied. It is shown that the unsymmetrical cyclic loading resulted in the fatigue of PPS coating, and had no obvious effect on steel. On the condition of constant stress amplitude, ratcheting strain and saturation ratcheting strain increase with the mean stress increased. On the condition of constant mean stress, ratcheting strain and saturation ratcheting strain increase with the stress amplitude increased,but mean stress has more effect on it than stress amplitude. Theσm ?Nfc curve for PPS was linear on the log-log coordinates under the condition that the stress amplitude was constant, and fatigue life increase with the mean stress decreased. TheΔσ/2?Nfc curve for PPS was also linear on the log-log coordinates, and fatigue life increase with the stress amplitude decreased.更多还原