Glass molding is a key technology for manufacturing optical components; however, adhesion between glass and molds during hot pressing can cause severe tool damage and reduce production yield. Although low surface free energy is commonly considered a criterion for anti-adhesion coatings, its ability to reliably predict glass–film interaction remains unclear. In this study, low-cost CrN and SiN thin films were fabricated and systematically evaluated using contact angle measurements, surface free energy calculations, glass contact tests, and hot-pressing experiments. The results show that coatings with lower surface free energy generally exhibit reduced adhesion in CrN systems; however, this relationship is not consistently observed for SiN coatings. A key finding of this work is that thermal stability, characterized by changes in contact angle after heating, plays a critical role in adhesion behavior. Coatings exhibiting minimal variation in contact angle demonstrate improved anti-sticking performance, regardless of their initial surface free energy. These results indicate that surface free energy alone is insufficient to predict glass adhesion. A combined evaluation approach incorporating both surface free energy and thermal stability is therefore proposed as a more reliable and physically meaningful framework for assessing anti-adhesion coatings in glass molding applications.
Nguyen et al. (Thu,) studied this question.