From the perspective of development history, coating is a very important development direction, in order to understand the importance of coating, we must understand the structure of piston rings. The latest piston ring construction includes a base material, a wear-resistant coating, a break-in coating and a side coating. In the early days, piston rings had only the base material, a break-in layer, no wear layer and no side coating.
structure of piston rings
1. The substrate occupies the vast majority of the piston ring;
2. The second is the wear-resistant layer, which is the most important part, and the ceramic coating is cermet, which is a composite coating material that is partly ceramic and partly metal. These two components are combined into one material, the metal part has high elastic durability, and the ceramic part has high temperature and seizure resistance, which improves the overall wear resistance of the piston ring.
3. The run-in coating is to be able to run in with the cylinder liner in the early stage, and the run-in coating is a bronze-based coating with alumina oxide insoluble substance, which has the following functions:
a. The break-in coating is used as a safety buffer to prevent cylinder pulling problems during the break-in process;
b. If the piston ring is worn and continued to be used, the cylinder liner will be formed black marks or hole polished, and the new piston ring will be replaced, and the matrix of the run-in coating can re-establish the open particle structure of the cylinder liner (graphite);
c. In addition, the running-in coating also reduces the fuel consumption of the cylinder during the running-in process.
4. The side coating is generally consistent with the piston ring groove on the piston head, chrome plating, and side wear leads to an increase in blow-by and LOC, and affects the running surface coating!
| Coating design | Coating form | Coating application |
| Alu,RIAS(RC) | Thermal spraying | running-in |
| Cermet | Thermal spraying | abrasion resistant |
| Cr,CKS,Chromium-Ceramic(CC) | Electrofacing | abrasion resistant |
The lifespan of the piston ring is significantly increased due to the ceramic wear-resistant layer
