Experimental investigation on chromium-diamond like carbon (Cr-DLC) coating through plasma enhanced chemical vapour deposition (PECVD) on the nozzle needle surface

This study emphases the reduction of droplet defect in nozzle needle during the application of Cr-DLC coating on the substrate. The coatings were carried out in the highly sophisticated chamber with attached coating setup under the vacuum atmosphere. The materials were assessed in terms of their adhesiveness, hardness, wear resistance, and microstructural morphology. The dry wear test result reveals the appreciable outcome of nitrogen (N-2) flushing on quality of interfacial bonding. The indentation confirms the superior morphology of coated substrates but yet insufficient to resist crack propagation due to weak in adhesiveness of chromium (Cr) layer under non-N-2 flushing. Scanning electron microcopy (SEM) embedded with energy dispersive X-ray (EDX) was deployed for analysis of cross-sectional coated of substrate. The statistical results claimed that the samples rejection without N-2 flushing was showed up to 1.2%. However, the results revealed that Cr-DLC coating with N-2 flushing reduced droplet defect and gain remarkable performance over a wide range of samples. Consequently, this novel methodology was employed to assess the coating performance by using a performance index based on tribological properties.