WC/TiC-based cermets are, generally, considered as potential alloys widely used in hot rolling industry because of their interesting properties, namely high resistance to wear and oxidation. This work was aimed at studying the tribological behaviour, at relatively high temperatur, of WC/TiC-based cermets prepared using the powder metallurgy procedure. Three WC/TiC-Co cermets were prepared with different titanium carbide (TiC) additions namely 5%, 10% and 15% [in weight percentage (wt.%)], and a tungsten carbide-cobalt (WC-Co) grade without TiC which was considered as a reference material, resulting in a total of four samples. Friction tests were carried out, at two different contact temperatures of 450°C and 650°C, using a tribometer and an alumina ball during 2 h 46 min with load and speed of 20 N and 0.5 m/s, respectively. The obtained friction coefficients indicate that WC/TiC-based grades are relatively stable compared to the reference grade which shows an unstable friction coefficient with many peaks. It was also found that wear rates decreased with increasing TiC content, but exhibited a noticeable increase with rising temperature. Moreover, and in order to characterise the tribological degradation, the wear tracks microstructure composed of 80% WC, 15% Co and 5% of TiC, were analysed using a scanning electron microscope (SEM) process. Consequently, an enhancement of the wear resistance at 650°C was observed, and oxides of various types rich in tungsten, cobalt and oxygen were identified through SEM/energy electron spectrometery (EDS) images.

The paper examines the friction and wear behavior of four different WC/TiC-Co cermets, where three of them are composed of 5%, 10% and 15% TiC additions, and a WC-Co grade without TiC, taken as a reference material for comparison purpose. The principal aim is to improve wear resistance to high sliding speeds (hot rolling) of the WC-Co material as a reference by adding previously-listed percentage of TiC. The samples (cermets) were prepared according to the powder metallurgy procedure, which includes the preparation of the powder mixture, its compression shaping and liquid phase sintering. Sintering was carried out at 1460 ° C, for 14 hours, in a reducing medium (H2). The TiC materials are added in order to boost hardness of the WC-15Co cermet and, consequently, its resistance to wear under thermomechanical conditions. The experiments are conducted using a pin-on-disc tribometer in contact with Al2O3 alumina ball at two sliding speeds of 0.5m/s and 0.75m/s, at a high temperature of 450°C, and a 20 N load.  It has been noticed that some recorded friction coefficients are unstable and exhibit many peaks during almost the whole friction test period. The obtained results from the SEM microscope show that the wear behavior of the new proposed material is improved, where it has been shown that, at the sliding speed of 0.75m/s, the greater the TiC percentage is, the lower the average friction coefficient will be. Also, for the speed of 0.5 m/s, the average friction coefficient is relatively more stable with the TiC percentage increase. Moreover, the obtained experimental results show an average wear rate decrease, with respect to reference grades (NA), that amounts to nearly 36% and 41% at the two sliding speeds P1 (0.5m/s) and  P2 (0.75m/s), respectively.

Fault Tree is one of the traditional and conventional approaches used in fault diagnosis. By identifying combinations of faults in a logical framework it's possible to define the structure of the fault tree. The same go with Bayesian networks, but the difference of these probabilistic tools is in their ability to reasoning under uncertainty. Some typical constraints to the fault diagnosis have been eliminated by the conversion to a Bayesian network. This paper shows that information processing has become simple and easy through the use of Bayesian networks. The study presented showed that updating knowledge and exploiting new knowledge does not complicate calculations. The contribution is the structural approach of faults diagnosis of turbo compressor qualitatively and quantitatively, the most likely faults are defined in descending order. The approach presented in this paper has been successfully applied to turbo compressor, which represent vital equipment in petrochemical plant.