Investigation of wear properties of carbide coatings produced by plasma transferred arc

One of the most desired features of moving steel machine parts used in industry is high wear resistance and hardness. Many different surface coating techniques are used to obtain these features. One of these techniques is the surface alloying process performed with Plasma Transferred Arc welding (PTA). It is seen that ready-made commercial powders are widely used in this technique. These powders are mainly produced using the gas atomization technique and have high financial value. This situation increases the cost of the coating process. Naturally, low-cost and high-strength powder production is important. One of the powders used in alloying with PTA is WC/Co powder, which is mainly composed of the same material as the sintered carbide cutting inserts used in machining. The surfaces of sintered carbide cutting inserts can be reused by sharpening them. It is known that these carbide-cutting inserts break and lose their sharpening properties after repeated use and become waste. The recycling process of these materials, which have high hardness and low dynamic toughness, is very costly due to their high melting temperatures. In the PTA process, metal or ceramic powders with one or more different chemical contents are alloyed on a softer metal substrate material with high energy input and local melting. Thus, a strong bond is established between the substrate material and powders with the high heat effect of the plasma, and the surface properties are improved. This study first provided the recovery and re-evaluation of broken sintered carbide cutting inserts that have lost their sharpening properties in the machining industry. Since they were very hard and brittle, they were recycled with the designed autogenous grinding system. The obtained WC/Co containing ground powders and low-cost commercial Fe, Ni, and C powders were mixed in different ratios by volume, and composite coatings were produced on structural steel surfaces with limited usage areas using the PTA technique. The produced coatings were characterized by microstructural, mechanical, and tribological properties.