Hot erosion wear and carburization in petrochemical furnaces

Micro-mechanical properties were determined for the QllOO coating and the uncoated steel substrate using a Fischerscope HIOOC microhardness indenter. Measurements were taken on mounted polished cross-section coupons. Several regions within the coating were surveyed. A fracture toughness value was determined for the coating using a hardness indentation approach [12, 13]. The indentation test conditions and mechanical properties measured are shown in Table 25.2. 

Thermal shock resistance tests were completed on the coating in order to assess its compatibility to thermal cycling and to study the coatings coefficient of thermal expansion (CTE) property. Five coated coupons were placed within a horizontal tube furnace and heated in an air atmosphere. A sample was removed from the furnace after being exposed to a specific temperature, namely, 400,500,600,800 and 1000°C. The dwell time for each temperature was 30 min. The removed sample was quenched in water at room temperature. 

Machine Fischerscope H100 Ultra-Microhardness Tester 

All quenched coated coupons were then sectioned, mounted and polished. These mounted samples were then examined by OM for any evidence of thermal shock damage such as cracking and spallation. It is recognized that water quenching from temperature is extremely severe relative to real-world conditions. 

The coating and reference steel were studied for their resistance to carburization. Four coated coupons were exposed to test conditions of 1100°C and a carbon activity of approximately 1 (a =1), for defined exposure times within a 

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