为缓解生物质焚烧发电过程中金属管道受热面的高温腐蚀问题，实现锅炉内长期纯烧/掺烧生物质，利用超高速激光熔覆技术在TP347钢管表面制备了Inconel 625合金防护涂层。利用SEM、EDS等表征手段分析了熔覆层的显微组织及元素偏析特征；通过自制的模拟生物质锅炉真实环境的高温腐蚀测试装置，对比研究了TP347耐热钢与Inconel 625熔覆层在550 ℃高温下的长期腐蚀行为。结果表明：工艺优化后的超高速激光熔覆Inconel 625涂层内部无明显缺陷，且与TP347钢基材形成良好的冶金结合界面；涂层组织由细小的固溶γ-Ni相和晶界偏析相组成，显微硬度为HV341；涂层内部的成分偏析较小，晶界偏析相中Ni、Cr合金元素未明显下降；2种试样的腐蚀增重随时间均呈线性增长，而Inconel 625涂层在550 ℃高温下500 h的腐蚀增重仅为TP347耐热钢的1/62，主要源于其较低的Fe含量和界面均匀腐蚀特征。通过超高速激光熔覆制备Inconel 625合金防护涂层，可有效提高生物质焚烧锅炉中管道受热面的耐腐蚀性能。

To alleviate the hot temperature corrosion problem for the heated side pipe from the biomass incineration,and achieve the purpose of long-term pure burning/blending of biomass in the boiler,the Inconel 625 alloy coating has been prepared on TP347 substrate by ultra-high speed laser cladding technique. The microstructure and elemental segregation of the cladding layer were characterized by SEM and EDS;a self-made hot temperature corrosion setup was used to simulate the real environment of biomass incineration,and the hot temperature corrosion properties of TP347 and Inconel 625 coating were comparatively tested at 550 ℃. The results show that the optimized ultra-high speed laser cladding Inconel 625 coating has no obvious defects and forms a good metallurgical bonding interface with TP347 steel substrate. The coating is composed of fine γ-Ni phase and the precipitate on the boundary,and the hardness reaches HV341. There′s barely elemental segregation inside the coating,and the concentrations of Ni,Cr show little decrease for the bondary precipitate. For two samples,the corrosion weight gain increases linearly with the corrosion time. The weight gain of Inconel 625 coating is only 1/62 of the TP347 steel at 550 ℃ for 500 h,mainly due to its low Fe content and uniform corrosion characteristics at the interface. The Inconel 625 coating by ultra-high speed laser cladding can effectively improve the corrosion resistance of the heated side pipe in biomass incineration boiler.

0 引言

1 试验

   1.1 超高速激光熔覆Inconel 625涂层制备

   1.2 Inconel 625涂层显微组织分析

   1.3 涂层高温腐蚀行为研究

2 试验结果及讨论

   2.1 熔覆层的显微组织分析

   2.2 熔覆层成分偏析分析

   2.3 耐高温腐蚀

3 结论