Wärmekontaktpunkt

Wärmekontaktpunkt (thermal contact point) refers to the localized region at which heat flows across the interface between two contacting solids. In practice, heat transfer occurs primarily through a network of microcontacts formed by surface asperities; the nominal contact area is typically larger than the actual conducting area. Because real contact areas are small and may be separated by oxide layers, contaminants, or thin gaps, heat transfer across the interface is limited by thermal contact resistance.

Several factors influence a Wärmekontaktpunkt: the contact pressure and load, the thermal conductivities of the involved materials, surface roughness, temperature, and the presence of interfacial films or thermal interface materials. Increasing contact pressure, using materials with higher conductivity, smoothing surfaces, or applying TIMs can enhance the thermal contact conductance.

Quantitatively, the heat flux Q across a Wärmekontaktpunkt relates to the temperature drop ΔT across the interface by Q = h_c ΔT, where h_c is the thermal contact conductance (the reciprocal of the thermal contact resistance). Microcontact theories (for example, elastic Hertzian contact) link h_c to real contact area and material properties, though real-world behavior often requires empirical or numerical models.

Applications of the concept include electrical contacts, electronic packaging, heat exchangers, and mechanical assemblies where efficient heat transfer across interfaces is important. Measurements employ steady-state or transient techniques and are often analyzed with asperity-based models or simulations.

See also: thermal resistance, thermal interface material, contact mechanics, heat transfer.