Effect on the film pressure distribution on a hydrodynamic tilting pad bearing caused by the coating of the journal with DLC by triboadhesion

This work is concerned with the effect on the film pressure distribution caused on a hydrodynamic tilting pad bearing, by the change in surface properties of the journal. Here two identical journals, both manufactured with AISI 9840, were employed. One of them was coated with DLC by the triboadhesion process, and the second, was used as a reference without applying any coating. During tests, the tilting pad experienced a lower film pressure distribution when the journal coated with DLC was employed. This phenomena could readily be attributed to the different surface energies of the coated and uncoated journals, which in time causes that the fluid film characteristics to be modified by the reduction of the shear stresses at the wall, thus reducing the maximum film pressure measured and shifting the maximum pressure to the line of symmetry, drawn from the center of the journal to the pin of rotation of the tilting pad.