Sliding wear of CrN, AlCrN and AlTiN coated AISI H13 hot work tool steels in aluminium extrusion

The frictional forces arising from sliding contact with aluminium produce considerable shear stresses on the CrN coating that degrade its integrity and its adhesion to the substrate tool steel. The CrN coating suffers the most extensive wear damage. There is a net improvement in the sliding wear performance of the AlCrN coating owing to a multilayered structure and a much higher hardness. However, AlTiN outperforms both CrN and AlCrN in sliding contact against aluminium owing to its exceptionally high chemical resistance against aluminium. The superiority of the AlTiN coating is confirmed by wear rates estimations. ⺠Adhesive interaction of nitride coatings with aluminium is the predominant wear mechanism. ⺠COF’s are 1.83, 1.68 and 1.41 for CrN, AlCrN and AlTiN coatings, respectively. ⺠CrN coating suffers the most extensive wear damage. ⺠AlTiN outperforms both CrN and AlCrN in sliding contact against aluminium. ⺠Wear rates are 6.0, 0.5 and 0.004 Î¼m3 N−1 m−1 for CrN, AlCrN and AlTiN coatings, respectively.