MIL-HDBK-1110
Figure 4
Drawing Illustrating Effect of Shape of Abrasive Particle on
Contour of Blast-Cleaned Metallic Substrate
d) Specific Gravity. Generally the more dense a
particle, the more effective it is as an abrasive. This is
because it takes a certain amount of kinetic energy to remove
contaminants from the surface and the kinetic energy of an
abrasive particle is directly related to its density (specific
gravity).
e) Breakdown Characteristics. Abrasive particles
striking the surface at high speeds are themselves damaged. The
way in which they fracture (breakdown) and/or in which they
change their shape and size is called their breakdown
characteristic. An excessive breakdown rate results in a
significant increase in dusting, requires extra surface cleaning
for removal of breakdown deposits, and limits the number of times
the abrasive can be reused.
f) Water-Soluble Contaminants. ASTM D 4940,
Conductimetric Analysis of Water Soluble Ionic Contamination of
Blasting Abrasives describes a conductivity test for determining
the level of contamination of metallic, oxide, slags, and
synthetic abrasives by water-soluble salts. SSPC AB 1 requires
that the conductivity of the test solution be below 100
microsiemens.
6.7.1.4
Abrasive Types. Abrasives fall into seven general
categories: metallic, natural oxides, synthetic, slags,
cellulose (such as walnut hulls), dry ice pellets (carbon
dioxide), sodium bicarbonate, and sponge. A summary of typical
properties of some of these abrasives is found in Table 9.
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