钢基身管内镀铬层下的激光淬火基体界面腐蚀与铬层剥落

INTERFACIAL CORROSION AND SPALLSTION OF Cr-PLATED COATING ON A GUN BARREL STEEL SUBSTRATE PRE-TRATED BY LASER SPIRALY QUECHING

钢基身管镀铬层在高温腐蚀性气体中服役,采用YAG激光器对身管内表面作螺旋线状离散淬火预处理后再电镀铬的复合工艺,形成了基体界面呈激光淬火区/激光未处理区周期性变化的铬层/基体结构.对该身管进行高温腐蚀介质为火药气体的靶场实验.对实验后的基体界面腐蚀形貌与铬层剥落的关系研究表明:次界面裂纹的形成是基体界面高温气体腐蚀的根本原因,基体界面腐蚀的结果是形成基体烧蚀坑,烧蚀坑上的铬层以断裂形式剥落.激光淬火预处理钢基体通过抑制次界面裂纹的形成避免了基体界面高温气体腐蚀损伤,提高了铬层的抗剥落能力.

To meet the technical requirement for service in hot corrosive gases environment of Chromium-plated coatings of gun barrel, a complex technology was developed to improve the performance of the coatings that YAG laser was used to pre-quench the inner surface of gun barrel in mode of helix and then chromium-coating was plated to fabricated the Cr-coating/substrate structure with peri- odically dispersed substrate interface with laser quenched zones and original ones. Thereafter, the treated gan barrels were experienced for field firing test. The hot gasous environment is real firing gases. The analysis of corrosion morphology at interface of coating/substrate shows that the main reason of hot gases corrosion of substrate at the interface is the sub-interfacial crack formation in the substrate, which may induce erosion hole at the initial cracks of substrate. Thereby Cr-coatings on the erosion hole would spall in mode of fracture. Laser pre-quenched substrate may surpress the interface corrosion damage by suppressing the sub-interfacial crack forming, for this reason, the spallation resistance of Cr-coatings is enhanced.