Experimental data on the erosion of brittle materials in abrasive particle flow are generalized on the basis of similarity and dimension theory using four similarity criteria. These criteria represent the influence of strength, fracture toughness, dynamic and total pressures resulting from the particletarget impact, and target temperature. The volume erosion rate is represented as power dependence of the similarity criteria. It is shown that strength characteristics and total pressure, which results from wave damping in the particle-target impact, are of major importance in the erosion of brittle materials in addition to the impact velocity. Dynamic pressure and temperature are of minor importance.
A plastic particle will adhere to a substrate after collision if the work of adhesion in the contact area exceeds the elastic rebound energy. The plastic deformation of the particle decreases the elastic strain energy and increases the probability of adhesion. A linear hardening plastic material with constant hardening modulus is used as a model. The particle is modeled by a disk with onedimensional stress distribution. Equations are derived to calculate the minimum speed of impact for the particle to stick to the substrate and the degree of "flattening" of the particle after collision. The model includes no empirical coefficients to be determined in spaying experiments. A new method to describe the effect of dynamic interaction on the activation energy for a topochemical reaction is proposed. It is demonstrated that the nature of plastic deformation changes after the contact stress becomes equal to the hardening modulus. In a high-speed impact, almost all of the kinetic energy is transformed into heat even if the plastic particle does not adhere to the substrate. The calculated results are in agreement with experiments on an aluminum powder deposited by cold spraying onto a copper substrate.
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