Tribological performance of high chromium white cast iron and heat-treated steel used in barite crushing industry.

Barite sulfate (BaSO4) is considered a very important mineral material employed as a weighting agent for all types of drilling fluids. Meanwhile, crushers used for the grinding step during barite crushing are affected by catastrophic wear damage located in the hammer parts made from high chromium white cast iron (HCWCI). In the present study, a comparison of the tribological performance between HCWCI and heat-treated steel AISI P20 was conducted to investigate the possible substitution of HCWCI. The tribological test was performed under normal loads between 5 and 10 N for different durations (60, 120, 180, and 240 min). The wear response analysis for both materials showed that the friction coefficient increases as the applied load increases. Moreover, AISI P20 presented the lowest value compared to that attributed to HCWCI in all conditions. Furthermore, the analysis of the wear track obtained by means of scanning electron microscopy (SEM) revealed that the damage was an abrasive wear phenomenon for HCWCI with detection of a crack network throughout the carbide phase, which was more pronounced under the highest load. Regarding AISI P20, an abrasive wear mechanism was detected, characterized by several grooves and ploughing phenomena. Further, the analysis of the wear track using 2D profilometry revealed that for both loads, the maximum wear depth of the HCWCI wear track was significantly greater than that of AISI P20. As a result, when compared to HCWCI, AISI P20 exhibits the best wear resistance. Furthermore, as the load increases, the wear depth and the worn area increase as well. Also, the wear rate analysis supports the previous findings, which showed that under both loads, AISI P20 was more robust than HCWCI.

Effect of Test Parameters on the Friction Behaviour of Anodized Aluminium Alloy.

The tribological behaviour of anodic oxide layer formed on Al5754, used in automotive applications, was investigated against test parameters. The friction coefficient under different normal loads, sliding speeds, and oxide thicknesses was studied using a pin on disc tribometer. Results show that the increase of load and sliding speed increase the friction coefficient. The rise of contact pressure and temperature seems to cause changes in wear mechanism. Glow-discharge optical emission spectroscopy (GDOES) was used to investigate the chemical composition of the oxide layer. Morphology and composition of the wear tracks were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of these characterization techniques, a wear mechanism was proposed. The observed mechanical properties can be related to the morphology and the chemical composition of the layer.