Why is low flow when heated important for high-temperature lubricants?
One of the main properties of high-temperature lubricants is the ability to keep their consistency when heated, without thinning and running out of the friction zone. Cheap imitations of high-temperature lubricants are made by mixing a grease such as «Litol» with copper powder. Such lubricants run out of the friction zone quickly when heated and stop working. AXIOM® high-temperature copper grease has a specially developed base which under any heating remains viscous enough to stay in the contact zone of the lubricated parts.
The packaging states that the high-temperature lubricant works at temperatures from -40°C to +1100°C. But an organic base burns off at 250°C, and a synthetic one at 400°C at most. How then does the lubricant work at higher temperatures?
AXIOM® high-temperature copper grease belongs to the class of release lubricants. Its main task is to protect parts from seizing when heated and to keep them movable relative to one another. It must therefore stay in the friction or contact zone of the parts at any temperature. The role of the lubricant here is played by the copper, and even if the base burns off, the copper will still remain and will do its job. The main thing is that the base does not run when heated and does not wash the copper out of the contact zone with it, as happens with cheap imitations of high-temperature lubricants.
Why is high adhesion of high-temperature copper grease to metal important?
For the lubricant to work effectively it must hold well on the friction surfaces. If adhesion is low, then as a result of the mutual movement of parts, for example the brake pad and the caliper, the lubricant will gradually be squeezed out of the friction zone and the pads will start to squeal when braking.
How well the lubricant holds onto metal can be checked with a simple test. Apply the lubricant to a smooth metal surface and wait 15-20 minutes for the solvent to evaporate. Then try to wipe the lubricant off the surface with your finger. If the lubricant wipes off down to the metal, it is of poor quality. If your finger slides and the lubricant stays on the metal, everything is in order.
It is also important that the high-temperature lubricant is not washed off by water and resists the action of the salt solutions contained in de-icing agents.
Can the quality of high-temperature copper grease be determined from its appearance? Does the colour of the lubricant matter?
After application the high-temperature copper grease should lie in an even layer, «colouring» the surface in shades from copper-gold to deep copper. By and large the shades do not matter; they differ between manufacturers and do not clearly indicate high or low quality of the lubricant. But if the lubricant lies unevenly and after application it can be seen separating into fractions, this is a clear sign of its low quality.
Are the electrically conductive properties of high-temperature copper grease good or bad?
Because high-temperature copper grease contains a large amount of copper, it is able to conduct electric current. This makes it possible to use it for treating, for example, battery terminals. At the same time, care must be taken when treating the threaded part of spark plugs before installing them in the engine, especially if you are using an aerosol. If you are careless, part of the sprayed lubricant may get onto the insulator separating the electrodes; it will become electrically conductive and the spark will start to «leak» to the plug body straight along the copper grease, bypassing the side electrode. The plug will be ruined.