Influence of Graphite and Polytetrafluoroethylene Dispersions on Mechanical, Abrasive, and Erosive Wear Performance of Thermal Spray Coatings

This paper examines the mechanical, abrasive and erosive wear properties of a thermal spray enhanced with randomly dispersed solid lubricants. Two different solid lubricants including graphite and polytetrafluoroethylene (PTFE) were mixed with a NiAl₂O₃ thermal spray to develop a stable thermal coating. The solid lubricants increased the wear resistance of the coating upon the erosion of the spray cover due to the friction of the mating surfaces. The wear and abrasive resistance were investigated by applying the developed thermal coating to a substrate manufactured by Bakelite. The maximum erosion rate was observed upon blasting abrasive Al₂O₃ powder at 30-degree angle and at an elevated temperature of 160°C. Spray coating with graphite illustrated a stronger surface adhesion and consisted of a superior hardness strength. A sliding steel indenter of 3 mm diameter and a 9 mm stroke length with speeds ranging between 20 to 70 cycles per minute was used to investigate the abrasion rate of the thermal coating. Furthermore, a pull-out test was applied to analyze the adhesive strength of the newly developed thermal coating. The results of the various experimental tests illustrated that Ni based thermal spray infused with graphite solid lubricants has significantly enhanced the lifetime of the thermal coating.