Affects various portions of exhaust systems on both diesel- and gasoline-powered vehicles. Various exhaust system components are protected from hot corrosion by the use of thermal sprayed aluminum via the twin-wire arc spray process or the wire combustion process.
Has been known to occur on the tops of pistons due to the impingement of fuel from the injectors. Aluminum pistons in diesel engines are frequently coated with a thin, plasma-sprayed molybdenum coating to circumvent this problem.
Of aluminum piston skirts results in the transfer of aluminum to the cast iron cylinder liners. Piston skirts are also coated with a thin molybdenum layer to prevent this.
Commonly consist of molybdenum and molybdenum-bearing compounds. Coatings are usually inlaid into the ring surface so that no exposed coating edges encounter the cylinder wall.
Cylinder bore coatings applied by thermal spray processes are now replacing hard chromium plating on the larger (wet) liners used in diesel engines.
Coatings have been largely limited to dimensional restoration of worn parts. Rebuilding of crankshafts for off-road equipment has also been performed with thermal spray.
As used on a number of passenger cars, frequently receive thin APS molybdenum coatings on the gear faces, lessening the friction component and producing smoother and quieter movement.