Avaliação da nitretação a plasma como alternativa ao revestimento de cromo duro em cilindros de laminação a frio

Abstract

The objective of this study is to evaluate if plasma nitriding is capable of replacing the hard chromium coating in rolling mill rolls. In the rolling industry, hard chrome is used in both rectified and textured rolls. For these two conditions, the tribological behaviour of nitriding and hard chromium were evaluated. This study presents papers that aim to reproduce the wear on rolling rolls. The methodologies suggested in the literature were used to evaluate the performance of plasma nitriding in rolls. After the tests, it was concluded that the use of plasma nitriding in rolling mill rolls is promising. The friction coefficient of the nitride samples was similar to the samples coated with hard chromium. The texture of the surface provoked the stabilization of this parameter in both conditions. The wear rate in samples of the nitrided and non-texturing samples was compatible with the values found for samples with hard chromium. However, the performance of nitriding in textured samples was slightly lower. The texturing considerably reduced the wear rate of the samples. Nitriding did not allow maintaining the topographic parameters Sq and Sdq after the wear. But, the Spk and Sbi parameters presented similar behaviour to the chrome sample.