In the recent coatings Focus article in Race Engine Technology (Issue 47, June/July 2010), there was brief mention of thermal dispersion coatings. The aim of these coatings is to eliminate surface ‘hot spots’ on components and thereby equalise the temperature. Their most common use is on cooling system components, although one supplier we spoke to said one of his customers found success using the coating on aluminium connecting rods, making them less prone to failure.
In terms of the eliminating surface hot spots, there are obvious advantages with being able to do this. There are many materials used in or around a race engine that experience a significant drop in mechanical and fatigue properties with increasing temperature. If we can achieve a better temperature distribution over the surface, we could avoid there being a premature failure at the hot spot. Read more…
There is wide agreement among racing engine manufacturers and builders that the source of much friction in the racing engine comes from the crankcase. These losses are not entirely due to the amount of lubricant in the crankcase, as I can attest from personal experience. But there can certainly be gains made in reducing frictional losses by minimising the amount of oil in the crankcase and better control of the oil that’s there.
In a previous article on polymer coatings, I considered their application to pistons. Using polymer coatings on piston skirts remains popular for reducing friction and improving running-in behaviour. They have also been used for the rapid development of optimised piston skirt profiles, and this has been discussed in peer-reviewed technical literature.
Some of the important design features of the con rod have been discussed briefly in the articles on the RET Monitor website, and there has also been a recent RET Focus article in the magazine on the con rod. In that Focus article, we mentioned coatings, but here is a good forum to expand on the material a little further.
There are a number of surface treatments which go under the generic term ‘phosphating’, but not all are used for the same purposes and equally not all will be potentially of use to us as engine designers or in specifying parts which will increase performance or reliability.
Nickel plating is a common process, but there are two main methods of producing a thin layer of nickel on the surface of a metallic object. The first is to use a traditional electroplating process whereby the parts to be plated are part of an electric circuit and form the cathodes. A rod of the plating metal is used as an anode. These are immersed into a bath of electrolyte commonly containing a salt of the metal to be plated. In the case of nickel plating, the salt used is Nickel Chloride. Quite often with electroplating, there are two or even three plating processes used for the best results, 
During research for a forthcoming Race Engine Technology magazine article, Wayne Ward discussed the matter of coatings as applied to racing engine pistons with a number of the well-known suppliers, designers and manufacturers of racing pistons. The more specific point of polymer coatings in racing engines has been recently examined on the RET Monitor website, and the application of these to racing engine pistons was discussed. The focus of the discussion of 
The use of polymer coatings in racing engines has been widespread for many years, but is to some extent being displaced by the newer generation of coatings such as titanium nitride, chromium nitride and DLC as examples. In a lot of circumstances the newer coatings are an improvement, but the coatings rely on the fact that there will be no significant deformation of the coated surface, otherwise the thin coating, which itself is brittle in comparison to the underlying substrate, can craze and flake off. Debris thus caused can, in some circumstances, go on to cause more serious failures elsewhere in the 
As far as threaded fasteners are concerned, there are a large number of coatings which can be applied, and in doing so we are generally seeking to address one of a small number of issues, the main ones being:
Whilst DLC seems clearly to be the favourite coating at the moment, there are some applications where it isn’t necessarily favoured, for various reasons.
