HärteZeitKurve

HärteZeitKurve, or hardness-time curve, is a graphical representation of how the hardness of a material develops as a function of time after a processing step such as curing, heat treatment, or aging. It is used to characterize the rate of hardening and to assess when a material reaches a sufficient or specified hardness for its intended use.

Measurement and construction involve preparing a representative sample and measuring hardness at predefined time intervals. Common hardness tests include Vickers, Rockwell, and Shore durometer scales, with time zero defined as the completion of the processing step or the start of curing. The resulting curve H(t) shows hardness on the vertical axis and time on the horizontal axis.

Typical shapes of the curve start with a rapid increase in hardness, followed by a slower approach to a plateau as the material reaches its final hardness. The curve can be used to determine processing windows, t90 or other time points to achieve a target fraction of final hardness, and to compare different formulations, curing schedules, or environmental conditions.

Applications span polymers (resins, coatings, adhesives), composites, and metals where post-processing hardening is relevant. In polymers, the curve reflects crosslinking and gelation kinetics; in metals, it relates to phase transformations or precipitation during aging. Factors such as temperature, humidity, test method, and specimen geometry influence the curve and should be controlled for reliable interpretation.