This development has been conducted by Japan Science and Technology Agency for solving global
warming problem.
A novel surfacing process is proposed for the inner bores of aluminum engines, which is the heaviest
parts of automobile. This process is characterized by a plasticized coating with the use of frictional
heat. Coating material is heated by frictional heat and plasticized by a rotating rod. The coating
material is metallurgically bonded to the aluminum cylinder by plastic metal flow. Process advantages
include no fusion of the substrate, minimized influence of heat, and sound coatings without any
porosity and crack. Another advantage is the fine-grained structure of the coated material that results
from the process.
As conclusions, a novel process was developed to coat the inner surface of aluminum cylinders with
fine-grained material with modified hardness. In the case of Al-Cu35% eutectic alloy coating, the
maximum temperature reached 700K. Higher rotational speed of core rod gave harder coating layers.
This is attributed to the development of fine-grain structure on increasing the rotational speed. No
defect was observed inside the coating layer as well as at the interface between substrate and coating.
An actual engine cylinder was coated by this friction surfacing process. In the result, sound interface
was obtained and the thickness of coating layer was uniform and thin.