Via one of our customers, we received two valves (so-called exhaust valves) from huge marine diesel engines. An exhaust valve is a valve that releases burned gases from a cylinder. Both valve stems were seriously damaged, so they asked us to repair them both. The valve stem handles controlling the valve during its upward and downward movement. This must be done perfectly especially during the upward movement, otherwise the valve will not close properly and may begin to leak.
First, the valve stem is pre-processed, then we provided the valve stem with a wear-resistant carbide coating. Last, we grind/polish the valve stem to the optimum diameter and roughness. A great advantage is that the optimum roughness in the coating surface can be "tuned" which will optimize the running qualities further. This ensures minimal wear of bearings and seals due to minimum friction. The exceptional wear resistance of the coating ensures that the roughness also stays in the coating. As a result, the running properties are and remain better than new for a long time.
The coatings sprayed with HVOF are characterized by a low porosity and a high bonding strength.
TOPCOAT CCR+ consists of a TOPCOAT 177 UHCR (nickel based superalloy) HVOF sprayed intermediate coating and a chromium carbide top coating, namely TOPCOAT CCR.
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