A method and apparatus for the evaluation and improvement of the mechanical and thermal properties of carbon-nanotube (CNT) and carbon nanofiber (CNF) arrays grown on a substrate is disclosed. The Young's modulus of a CNT/CNF material is measured by applying an axial compressive force on the CNT/CNF array and measuring the applied forces and the induced displacements. Also disclosed are the evaluation of the nonlinear stress-strain relationship of the CNT/CNF material, increasing of the Young's modulus and decreasing the thermal resistance by application of a compressive load, the application of rapid thermal annealing to improve the quality of the CNT/CNF material and to reduce the interfacial thermal resistance, improvement of the bonding strength of the CNT/CNF array to a substrate, evaluation of the bonding strength of the CNT/CNF array to a substrate, evaluation of the shearing force at failure, and an analytical stress model that enables one to predict the interfacial shearing stress from the measured force.