Thermal Spray in Automotive

Automobile Manufacturing is an increasing market for thermal spraying and the number of coating applications grows steadily. The different coating applications are related to the power train components, thermal barriers protecting certain components from overheating, brake discs, cylinder bore in diesel engines, aluminum alloy cylinder bore, exhaust valves, crankshaft, transmission and rear end gear clusters, body and chassis, synchronizer rings, shifter forks, valve seats, and connecting rods.

Hot Corrosion

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.

Rain-Drop Erosion

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.

Galling

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.

Piston Ring Coatings

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 in Diesel Engines

Cylinder bore coatings applied by thermal spray processes are now replacing hard chromium plating on the larger (wet) liners used in diesel engines.

Crankshaft

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.

Transmission and Rear End Gear Clusters

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.

Typical examples of applications are shown in the table below:

 

NameAgePhoneCoating Function and RequirementCoating Process
Tom5010281065High scuffing and wear Resitance
Jerry4012540515
Halum12011511441