ABSTRACT

Hard chromium plating was performed to prevent the cavitation erosion of a diesel engine cylinder liner and the damage characteristics of the plating layer were analysed by conducting a cavitation erosion test with an amplitude of 50 µm according to the ASTM G-32 standard in a coolant. The surface damage was analysed using a scanning electron microscope and a 3D optical microscope before and after the test, and the weight loss of the specimen was determined. The surface analysis result showed the occurrence and growth of local damage of micro-tunnel shape on the surface of the plating layer, and both the surface damage depth and weight loss tended to increase. This local damage was observed to occur and grow first in the spherical grain microstructure of the plating layer. Consequently, it is thought that cavitation erosion attack will cause local damage of the hard chromium plated cylinder liner.

摘要

为防止柴油发动机气缸套的气蚀而进行了镀硬铬，并通过在冷却剂中根据 ASTM G-32 标准进行幅度为 50 µm 的气蚀试验来分析镀层的损坏特性。采用扫描电镜和3D光学显微镜对试验前后的表面损伤进行分析，测定试样的失重。表面分析结果表明，镀层表面出现了局部微隧道状损伤，且表面损伤深度和失重均呈增加趋势。观察到这种局部损伤首先在镀层的球形晶粒微观结构中发生和生长。最后，