Tribological Study of Aluminum 390-T6, Gray Cast Iron, and Manganese-Silicon Brass as Metallic Interfaces for AC Compressors in the Presence of CO₂

19^th International Compressor Engineering Conference at Purdue

Carbon dioxide (CO₂) has received interest as an alternative refrigerant for air-conditioning compressors due to its environmental benefits. These environmental benefits include zero ozone depletion potential (ODP) and low global warming potential (GWP) compared to commonly used hydroflurocarbon (HFC) refrigerants. The tribological behavior of material pairs commonly used in air-conditioning compressors under the presence of CO2 has not been extensively studied and only limited published works are available. Evaluation of typical tribo-contacts included Al390-T6, gray cast iron, and Mn-Si brass (UNS C67300). These materials were tested against 52100 hardened steel pins using a pin-on disk configuration. The tests were performed using a High Pressure Tribometer (HPT) in the presence of CO₂ and polyalkylene glycol (PAG) lubricant. Results showed that the scuffing resistance of gray cast iron and Mn-Si brass was similar and both materials performed better than Al390-T6.