【作者】 杜艳玲；

【导师】 邱长军；

【作者基本信息】 南华大学 ， 机械制造及其自动化， 2005， 硕士

【摘要】 热喷涂技术的优点是生产效率高,选材广,可在大工件上得到厚涂层,这是其它表面技术所不及的。热喷涂技术在工业中有着广泛的应用,但由于现有技术的热喷涂涂层与基体的结合主要依靠机械物理结合,涂层结合强度不高,严重影响了它在苛刻工况下的应用,涂层最易出现失效的环节也在界面上。在热喷涂涂层的形成过程中,涂层材料与基体间的结合强弱是影响涂层性能的关键。 采用传统氧—乙炔火焰粉末喷涂设备在不引起Ni/Al放热反应的情况下,将Ni-Al粉末喷涂于Q235基体上,在氢气保护气氛炉内经中温处理,利用OM,SEM,EDX等对涂层界面进行了观察、研究、分析,对涂层界面结合强度提高因素作了综合研究;为了阐明中温作用增强涂层结合性能的机制,利用纯铁表面氧化和中温还原处理,直接观察到了微裂纹的愈合及还原生成的Fe原子在Fe表面的结晶形态,揭示了中温处理增强涂层结合性的机制,本研究的主要结果有: <1> Ni-Al涂层中温处理后界面结合强度明显高于常规涂层;界面出现约10μm的Fe-Ni固溶区,界面呈现分区冶金结合;界面显微硬度高出涂层及基体约20HV,EDX分析表明界面主要是Ni-Fe固溶体相,并在4～5μm宽的范围内可能存在Ni₃Fe有序固溶体。 <2> 纯铁表面微裂纹可通过氧化—还原处理在993K条件下实现自愈合,还原反应生成的铁原子在表面凝聚结晶时呈现出明显的准有序层状结构,层片厚度在100nm左右。 <3> Ni基、Cu基、Co包WC涂层中温处理后界面结合强度明显高于常规涂层,界面组织在未腐蚀条件下与基体连成一片,没有常规涂层所有的明显分界;腐蚀后的可见明显“锯齿”状新相,表明界面有新相生成。 <4> 中温处理增强涂层结合力的过程可近似概化分为为三个阶段:①应力驰豫;②金属氧化膜在Al、H₂的还原作用下形成层状准有序结构体;③中温作用下互相紧密接触且表面具有这种层状结构的金属颗粒之间的结合过程。更多还原

【Abstract】 The advantage of hot spraying technology is high efficiency and wide selecting suitable materials, it can get form coating on big work piece, which are other surface technology can’t be obtained. It has extensive application in industry in hot spraying technology. But particle hot spraying coating of technology rely on mechanically physics combined mainly. Layer structure of hot spraying coating and not-too-high bonding strength unit its application under harsh circumstance. Also the interface is the first abate position. During the form of hot spraying coating bonding strength between the material and coating is the key problem.When Ni and A1 powder is mixed without reaction, by means of the traditional oxygen - the acetylene flame powder spraying equipment Ni-A1 powder on Q235 and heat treatment with H2 as protection atmosphere, Utilize OM, SEM, EDX, etc. have observed to the coating interface, research , analysing, combine to coating interface intensity raise factor act as comprehensive research; In order to expounded the mechanism which coating combine is strengthened under middle temperature treatment, utilize pure iron surface after oxidizing and reduce reaction under middle temperature.Have observed the self-healing of the microcrack and reduced the crystallization shape on Fe surface of Fe atom produced directly. The mechanism is opened which strengthens coating associatively under middle temperature treatment. The main result of this research is as follows,<1> Ni-Al coating middle temperature treated interface combine intensity obviously higher than the routine coating; It is about 10μm that there are the interfaces Ni-Fe solution area, and appear divide metallurgy combine on interface: It is shown that HV on the interface is obviously higher than that of the substrate and the coating by 20HV. The results更多还原