Prior art techniques for testing abrasion resistance, such as the Taber test and the Bayer test, typically use a rubbing or scratching mechanism to test materials for abrasion resistance; specifically, either an abrasive material is rubbed across the test sample surface, or the test sample is rubbed against an abrasive surface. While these tests do provide valuable data, they do not accurately or reliably predict resistance to impact damage from wind-borne particulate matter. These prior art techniques are typically used to test hard protective coatings to determine their resistance to scratching; however, such protective coatings are prone to shattering upon impact of a fast-moving object, such as a grain of sand.
Consequently, coatings and materials may pass a prior art abrasion test, but fail rapidly when exposed to an environment in which there is blowing or airborne particulate. Furthermore, many prior art abrasion testers use a relatively slow timescale damage event that is not representative of the applied stresses and strain rates induced by the impact of windborne or airborne particulates. The timescale of the impact is significantly shorter than the damage from a prior art rubbing-type test that may cause a shift in polymer materials from ductile to brittle failure modes.
An apparatus was developed that generally comprises a primary air-stream-generating device to generate a primary air stream, and a secondary air-stream-generating device to produce a secondary air stream. It also includes a particulate handling device to deposit particulate into the secondary air stream. The particulate handling device may comprise a device to meter the particulate into the secondary air stream, or a motorized auger.
In one embodiment, the apparatus comprises a conduit network, a primary air-stream-generating device to generate a primary air stream in the conduit network, a secondary air-stream-generating device to produce a secondary air stream in the conduit network, and a particulate handling device to deposit particulate into the conduit network so that the particulate enters the secondary air stream. The conduit network merges the secondary air stream into the primary air stream to allow the particulate to enter the primary air stream, and allow the primary air stream to blow the particulate at a test sample positioned within the conduit network.