Wear and Friction Behavior of NiCrBSi Coatings at Elevated Temperatures

In many hot forming operations, the dies are subjected to high temperatures and high contact pressures. To combat wear problem, it is essential to select the accurate die material, hardness and surface coating for increasing the die life. This paper is an investigation into the use of NiCrBSi coating as a wear-resistant material on the H11 tool steel. The coating was developed by high-velocity oxy-fuel spray and atmospheric plasma spray process. In-depth characterization of the as-sprayed specimens was done by field emission-scanning electron microscopy/energy-dispersive spectroscopy and x-ray diffraction techniques. The mechanical and physical properties of the as-sprayed coatings were measured. Thereafter, the tribological performances of the uncoated and coated specimens were studied on high-temperature pin-on-disk tribometer under two different loads and temperatures ranging from room temperature to 800 °C. Wear mechanisms were mainly oxidative and adhesive at 400 °C and a combination of oxidative wear, abrasive wear and adhesive wear at 800 °C for the HVOF-sprayed and the APS-coated specimens.