A semi-mechanistic model for the erosion of different target materials due to solid particles has been proposed based on the experimental data from direct impingement testing. As a first step in erosion experiments, particle velocity has been measured with Particle Image Velocimeter (PIV) at different gas velocities. A new mechanistic model, with incorporated empirical constants, has been developed by assuming that erosion caused by particle impact is due to two mechanisms, cutting and deformation. This hypothesis is supported by the SEM images of the surface of the eroded specimen at different locations. Empirical constants have been obtained for different target materials using data from erosion tests with 150µm sand particles. In contrast to the angle functions that are currently being used for all particles and impact velocities, the angle dependence in the new model changes with the particle shape and velocity and showed fair agreement with experimental data.