Nanotip-Induced Ultrahigh Pressure-Sensitive Cement-Based Composite and its Pressure-Sensitive Characteristic Model

Abstract

A smart composite is fabricated from cement-matrix and spiky spherical nickel powders. The electrical resistivity of such composite decreases 69.00% under uniaxial compression. The gage factor of this composite is higher than 895.45 within the elastic regime. This ultrahigh pressure-sensitivity is attributed to the unique needle-like surface morphology of nickel powers. Comparing to the normal smooth spherical nickel particles, the needle-like features of spiky spherical nickel particles can induce field emission and tunneling effects, which leads to highly sensitive responses to strain. A constitutive model relating the change in electrical resistivity to strain of the composite is built within the elastic regime. This model incorporates the field emission effect and the inter-particle separation change of nickel powders in composite. The model is used to predict the pressure-sensitive characteristic behavior of the composite. The predicted result is compared with the experimental data obtained on the composite, and good agreement is obtained.