A side-by-side comparison of intake valves removed from a NASCAR Nextel Cup engine. The valve on the left is coated with Casidiam(r) while the other is uncoated. Each valve has gone through 1.5 million cycles.
Component life in a racing application has always been important. The idea of throwaway parts is not embraced by successful teams. If there's a way to get extended life, it has to be considered. If that extended life comes about without noticeable degradation of performance, that's even better. The valve application is one in which the customer's goal was to reduce performance degradation as well as extend part life. This team used to lose approximately 7 to 8 hp by the end of a race due to seal degradation between the valve and the head. Casidiam(r) reduced degradation to 1 to 2 hp.
Top-level racers have turned to the use of Casidiam(r), a diamond-like carbon thin film that can be applied on certain parts. While the technology may be new on this side of the pond, it has been around for five years, and European racers have been utilizing it for nearly 13 years. Through the efforts of Denver, North Carolina-based Anatech Ltd., teams are beginning to understand how some components withstood the rigorous requirements of formula racing.
Parts are placed within the vacuum deposition system chambers for the processes to run the
"We serve many of the top teams in NASCAR," says Anatech founder and President George Barr. "From there, we just keep drilling into the ranks of the circle track market." The technology can also be found in road racing and drag racing applications.
Wristpins for pistons became the starting point for racers to realize the benefits of the process. Now there are other areas where Casidiam(r) coating can play a key role in product performance.
"The biggest area seems to be in the engine," continues Barr. "We do work on steering system parts and shock shafts. It can be applied to steel, stainless steel, aluminum, and titanium. Casidiam(r) cannot be used on materials like zinc, tin, copper, and brass. These metals are not vacuum friendly."
By the nature of its role in the engine, the camshaft is a key candidate for the efficienc
Creating the Coating Casidiam(r) uses the Plasma Assisted Chemical Vapor Deposition (PACVD) process, a derivation of the Physical Vapor Deposition (PVD) process that has been the cornerstone of Anatech since it was founded in 1981. In the PACVD process, a vacuum pump evacuates a chamber to proper pressure after the parts have been placed inside the chamber. A gas is introduced with the proper hydrocarbon composition as well as other components. A radio frequency is used to crack the gas into a plasma state. Plasma is a forced state of matter that will spread out and flow in a laminar fashion needed for this process. Since the chamber wall quenches the plasma, the parts cannot be placed too close to that wall. Plasma is the most prevalent state of matter in the universe. And, while its existence is forced in the chamber, it's pretty easy to create. It's harder to control. It's known as the fourth state of matter.
The plasma is an ionized gas with roughly an equal number of positively (ions) and negatively (electrons) charged particles and neutrals.
This process can be simplified by comparing it to a fluorescent light. You have two electrodes that crack the gas contained within the vacuum tube (light bulb) to create the light from the fixture.
The process will allow the hydrocarbon plasma to pass by the parts, and the carbon will condense onto the parts. Since the plasma temperature is higher than that of the parts being coated, it will condense one molecule at a time. The particles arrive at the same energy level with a 90-degree attitude to surface application. The plasma evolves to a solid on contact with the part. The ions can be attracted to the part surface with an electrical bias. Most of the bonding is done chemically, which is nine times stronger than a mechanical bond. The PACVD process is more conducive to chemical bonding than the PVD method.