Editorial Feature

Gold as a Lubricant Preventing Cold Welding

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Gold can be utilized as a lubricant in a variety of engineering applications, depending on its resistance to cold welding.

Controlling Friction in Engineering

One of the key engineering requirements in several applications is the control of friction. Under low pressures, films on metals lost due to friction or other effects are not replaced. Consequently, metal surfaces that contact each other can easily cold weld to each other.

In space, this problem magnifies because, in certain external conditions, non-metallic lubricants might suffer from chemical breakdown, evaporation, or radiation damage.

Thanks to its low shear strength, cold welding is not a serious issue with gold, unlike what other metals face in such situations. Therefore, it has been used as a solid film lubricant in many space conditions that involve moving parts, both only as a surface coating on the bearing surfaces, and together with low-volatility synthetic lubricants.

Commercial Applications of Gold Lubricants

In China, the lubricating properties of gold are also being leveraged in a niche commercial application. The NanoGold Oil™ is an additive for diesel or petrol engines, claimed to provide power enhancements and fuel savings, and also reduced engine noise. Conventionally, graphite can be used as a component of cylinder coating additive, in combination with polytetrafluoroethylene (i.e., Teflon).

According to the claim of the manufacturers, gold is the finest material for a cylinder coating additive, yet it is hardly used due to its high price and limitations of milling technology.

NanoGold Oil™ is based on a liquid additive that consists of gold nanoparticles and synthetic oil. It is believed that these additives coat a layer of gold on the engine’s cylinder and piston surface. Additionally, it is also coated on lower parts of engines like shaft and camshaft, thus filling and sealing any possible micropores and pits.

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