The components in an automobile engine are often made from a range of different materials. The variations in the metallurgical properties of these materials can cause mechanical parts to absorb or disperse heat at different phases in the engine cycle. Regulating these temperature fluctuations among both internal and external engine parts can improve horsepower and performance characteristics, leading to more efficient vehicle operation.
Ceramic coatings are increasingly used to provide protection between different engine parts, helping to increase wear resistance, reduce friction, and improve heat shielding. These factors have a significant influence on horsepower ratings, and augmenting them through ceramic coating can often enhance an automobile’s performance. In addition, these coatings enable metal components to interact in a more uniform and compatible fashion.
Applying a Ceramic Coating
Before a ceramic coating is applied to an automotive component, the component’s surface is typically treated with a smoothing agent or sandblasting in order to remove the uneven outer surface and any contaminants that may have accumulated. After the clean bottom layer is revealed, the part is often heated in an oven to reduce its molecular porosity. Without this treatment, any contaminants remaining after the initial stage may be brought to the surface, forcing the coating layer to detach from the substrate.
Common automotive ceramic coatings, such as titanium and tungsten, are usually applied with a gravity-fed spray gun. The gun’s nozzle tends to be narrow to provide precise application control. Solvent coatings are typically sprayed at lower pressure, while liquid-based coatings are sprayed at higher pressure, but in both cases the process occurs inside a spraying booth. During spraying, it is important to keep careful control over the ceramic layer’s thickness, as the coating must be very thin and evenly distributed in order to keep it from running.
Inspection and Curing
Once the coating stage is complete, the component is examined to evaluate the uniformity of the ceramic film distribution. It is then air dried to allow the evaporation process to occur, and placed in an air-circulation curing oven that will provide an even heating treatment. Curing is performed at incrementally rising heat to address temperature transition phases, and most processes begin at roughly 175 degrees Fahrenheit before rising to a maximum of 600 degrees. The component is often burnished to achieve a more precise thickness level and to ensure it meets clearance requirements. Depending on the part, additional finishing treatments, such as vibration polishing, can be performed.
Two of the most common applications for automotive ceramic coatings involve exhaust manifolds and headers. A ceramic coating applied to a manifold or header will provide increased resistance to corrosion, such as rust, and lower the rate of heat loss, resulting in greater power output. When applied to internal headers, these coatings increase the speed of the exhaust gas and reduce overall turbulence by providing a smoother surface. Some other automotive components commonly coated with ceramics include:
Cylinder Heads: Applying a ceramic coating to a combustion chamber’s cylinder head and exhaust ports helps circulate exhaust gas at a faster pace while providing a more intense burn in the chamber. This coating can also improve thermal transfer between the gas and the cylinder head, and an additional heat dispersal coating can help cool the head.
Pistons: A piston can be made more efficient with a ceramic coating, which improves the device’s heat reflection and transfers part of the detonation energy into the fuel burning phase. This can result in higher fuel burning efficiency and reduced carbon accumulation, which in turn makes detonation more effective.
Piston Skirts: Coated piston skirts provide a dry sliding surface for engine startup, and feature increased resistance to abrasion and scratching while moving within the engine block. A ceramic coating can also be layered on the piston ring to reduce friction and enhance wear resistance between the ring and the cylinder’s inner surface.
Intake Manifolds: An intake manifold with an interior ceramic coating exhibits a lower level of heat penetration and a cooler mixture of air and fuel. Applying an oil dispersing coating to the bottom of the manifold can also lower heat transfer between the oil and the intake.
Ceramic coatings are often available in specific formulations designed to focus on thermal resistance, friction reduction, corrosion resistance, or oil shedding. These specialized coatings can be used to deliver a particular material characteristic without compromising the rest of the component’s properties.