Particle velocity v0 at the moment of hitting the target surface has the highest
influence on erosion rate. An early fundamental study on erosion conducted at the
University of Stuttgart was published in [7]. Quartz sand from the Neckar River
used for testing was, accelerated by the Stotz pneumatic device. Particle velocity
was assumed to be equal to the velocity of the air stream that was changed within
the range of 35 to 330 m/s.Two types of steels were investigated (steel St37 and
hardened steel C60H), together with molten basalt and rubber. At the impact angle
of 90°, test points obtained for all the above materials fall in a log graph in straight
lines, whose gradient determines the value of exponent m in Equation 1.7.: