Determinação do coeficiente de expansão térmica de materiais opacos por meio da medição de transmitância de um pinhole

Abstract

This study proposes an alternative approach to determine the coefficient of thermal expansion of opaque materials, using the technique of transmitting light through a 100 micrometer pinhole in a brass sample. Experiments were conducted with temperature variations in a furnace to measure the pinhole transmittance and, consequently, calculate the thermal expansion coefficient. The results obtained revealed that, although the technique has potential, there are still challenges to be overcome, since the calculated values of the thermal expansion coefficient (for example, α = (203 ± 5) × 10−6 1/°C) remained approximately 10 times higher than the expected value. However, these efforts contribute to the continuous improvement of this technique and represent an important advance in the development and application of the pinhole technique to opaque materials.