A nickel alloy cylinder plated with chromium along its inner liner, installed in a commercial ice cream freezer, showed gray discoloration along its OD surface. The discolored parts exhibited significantly reduced cooling efficiency as compared with new cylinders. During operation, the OD of the cylinder was exposed to liquid ammonia refrigerant containing lubricant from the compressor. The lubricant (mineral oil) was intended to separate from the ammonia and be recirculated through the compressor. Nondestructive portable optical microscopy, XRF, EDS, and XPS analyses showed that the discoloration on the cylinder was associated with metal oxidation products coated with a thin...
S.J. Suess, Discoloration of a Freezer Cylinder, ASM Failure Analysis Case Histories: Failure Modes and Mechanisms, ASM International, 2019, https://doi.org/10.31399/asm.fach.modes.c9001628
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