The corrosion can exacerbate due to the wear (rubbing) or be less than in a nonrubbing situation. If a plus or minus effect is due to the rubbing, synergy is said to exist. There is an ASTM test (G 119) quantifying the synergy in a tribocorrosion system. There are lots of details involved, but the way this works is: run a slurry abrasion test in a given slurry and measure the mass loss and volume loss; repeat the test with the slurry buffered so that it is noncorrosive to the test specimen. The difference between these results is a measure of the synergy. In most cases, the rubbing action on a surface increases its corrosion rate.