endoLube

An endothermic additive from RIMSA (like endoLube or enviroLube) is an engineered composite with a dual, temperature-dependent mechanism of action. It is not just a lubricant but an encapsulated "smart system." Each particle contains:

• A low-melting-point metallic core (e.g., Bismuth, Tin, or eutectic Sn-Bi alloys).
• A matrix of chemically active additives (sulfides) surrounding it.
• A polymeric coating that holds everything together.

Its function is twofold:

1. At low-to-medium temperatures (<400°C): It acts as a chemical heat sink. The metallic core undergoes a phase transition (melting), which is an endothermic reaction, meaning it absorbs heat from the pad-disc interface, actively cooling it.
2. At high temperatures (>400-500°C): The composite decomposes in a controlled manner and releases metal sulfides (e.g., SnS, Bi₂S₃) in-situ, directly onto the friction surface. These sulfides act as high-performance lubricants, forming a protective tribofilm that stabilizes friction and drastically reduces wear.

The fundamental goal is to replace copper in "Copper-Free" formulations and improve overall performance. Copper is traditionally used for its high thermal conductivity to dissipate heat. Endothermic additives achieve the same objective (thermal management) but through a much more efficient chemical mechanism (heat absorption), which allows for:

• Reducing peak temperatures at the braking interface.
• Minimizing brake fade (loss of performance due to temperature).
• Significantly reducing pad and disc wear at high temperatures.
• Lowering particle emissions, a key requirement for future regulations like Euro 7.

The main difference lies in the low-melting-point metal used in the core, which allows for "tuning" the temperature range in which the endothermic effect is active:

• enviroLube (Tin-based, Sn): Tin melts at ~232°C. It offers excellent protection across a wide range of Passenger Car (PC) and Commercial Vehicle (CV) applications.
• endoLube (Bismuth-based, Bi): Bismuth melts at ~271°C. It is a more cost-effective alternative to tin for mid-range applications.
• ri-Lube (Eutectic Tin-Bismuth alloy-based, Sn-Bi): This alloy has a very low eutectic melting point at 139°C. It is the ideal solution for activating at lower temperatures, protecting the pad from the early stages of braking and offering a wider thermal protection range.

The mechanism of action is unidirectional and temperature-activated. Within the body of the pad, the additive particles remain intact. Only the particles on or very near the friction surface are activated when the local temperature exceeds their melting point. As the pad wears, new layers of material containing "fresh" endothermic additive particles are exposed, ready to be activated. In this way, the protection is constantly renewed throughout the service life of the pad.

The encapsulated composite structure is the key to its superior effectiveness:

• Localized Action: By having all components in a single particle, the endothermic reaction and subsequent sulfide release occur exactly where needed: at the "hot spots" of the interface.
• Controlled Release: The polymeric coating and sulfide matrix ensure that the lubricating sulfides are released gradually at high temperatures, not prematurely.
• Formulation Efficiency: Smaller dosages of an endothermic additive are required to achieve the same effect as larger amounts of its individual components, optimizing costs and space