What do VI improvers do physically?

Der Einsatz von VI-Verbesserern (VI = Viskositätsindex) ermöglicht die Herstellung von Mehrbereichs-Motorenölen. VI-Verbesserer erhöhen bzw. strecken die Viskosität eines Öles und verbessern somit das Viskositäts-Temperatur-Verhalten. Sie sind bildlich gesprochen sehr lange, faserförmige Moleküle, die im kalten Zustand zusammengeknäult im Öl vorliegen und hier der Bewegung der Ölmoleküle einen relativ geringen Widerstand entgegensetzten. Mit zunehmender Temperatur…

What is the physical effect of corrosion protection additives?

Korrosion ist allgemein der chemische oder elektrochemische angriff auf Metalloberflächen. Für den Korrosionsschutz eigen sich bevorzugt grenzflächenaktive Additive, die sowohl aschefrei als auch aschegebend sein können. Die polare Gruppe lagert sich an Metalloberflächen an, der Alkylrest bildet dichte, pelzartige, hydrophobe (wasserfeindliche) Barrieren. Aufgrund ihrer polaren Struktur stehen die Korrosionsschutz-Additive im Wettbewerb mit EP/AW-Additiven, d.h. sie…

What is the physical effect of friction modifiers?

Friction-reducing additives, so-called friction modifiers, can only act in the area of mixed friction. These active substances form fur-like films on the surfaces (physical process), which can separate metal surfaces from each other. Friction modifiers are very polar, i.e. they have a high affinity to the surface combined with friction-reducing properties.

What is the physical effect of antifoam additives?

Polysilicones (silicone polymers), polyethylene glycol ether and others reduce the foaming tendency of an oil. This is achieved by trapping fewer gases (air and combustion gases) in the oil. On the other hand, trapped gases can escape from the oil more quickly. Foaming significantly impairs the lubricant properties (oxidation, pressure behavior) of a lubricant. A lubricant with poor foaming behavior can lead to significantly higher oil temperatures, wear and...

What do dispersants do chemically?

Dispersants have the task of enveloping solid and liquid contaminants that are introduced into the oil during engine operation and keeping them finely distributed in suspension. This prevents deposits in the engine. A distinction is made between two active processes: Peptization: This refers to the coating and suspension of solid contaminants in the oil, such as....

What do antioxidants do chemically?

Lubricating oils tend to age (oxidation) under the influence of oxygen and heat. This decomposition process is further accelerated by acidic reaction products from combustion and traces of metals that have a catalytic effect (abrasive and corrosive wear). The addition of antioxidants provides significant protection against ageing. The ageing process, oxidation, cannot be prevented by this, but it can be slowed down considerably. ...