CHROMIUM NITRIDE COATINGS GROWN BY UNBALANCED MAGNETRON (UBM) AND COMBINED ARC UNBALANCED MAGNETRON (ABS(TM)) DEPOSITION TECHNIQUES/

Increasingly chromium nitride coatings are being used as a replacement for electroplated hard chromium in various applications. This palter reports an investigation of chromium nitride coatings deposited at 250 degrees C on various substrates at different N-2 partial pressures us ing both UBM sputtering and ABS techniques. The effect of process para meters oil structure, composition, hardness and adhesion have been inv estigated by XRD, SNMS, SEM and a range of mechanical testing techniqu es. The presence of Cr, Cr + N, Cr2N, CrN, and mixtures of the phases have bees identified and related to both the film composition and the process parameters. Substoichiometric Cr2N films had the greatest hard ness with values up to 2100 HV. However, films of this hardness exhibi ted poor adhesion with critical loads, L(c), of 30 N (HSS) and HR(c)-D B of ''4'', if deposited with UBM only. X-ray diffraction indicated th at the poor adhesion exhibited by these films was associated with high internal stress. The adhesion of substoichiometric films with compara ble composition and crystal structure deposited in combination with me tal ion etching (ABS) increased the critical load values up to 60 N (H SS) and improved the HR(c)-DB to ''1'' (HSS).