Nanotextured Mold Surface with DLC Coating for Reduction in Residual Ceramic Particles

Abstract

In the ceramic industry, ceramic particles remain on a mold surface due to which the mold requires frequent cleaning during press molding, reducing productivity. Surface texturing and tetrahedral amorphous carbon (ta-C) coatings are well-known surface-energy controllable treatments developed for low adhesion, low friction, and high wear resistance. In the present paper, we demonstrate the effect of reducing ceramic residues using nanotexturing, ta-C coatings, and their combination. We compare two surface morphologies (i.e., 770 nm pitch nanotexturing and flat) and five materials (i.e., nonhardened steel, hardened steel, ta-C, and two types of nitrogen-doped ta-C (ta-CNx). Molding test results show that the ta-C coating on flat surfaces with the highest hardness of 30 GPa shows the lowest residual amount of 5.9 μg for Al2O3 ceramic particles. The amount is 82% less than that of the nonhardened steel. The ta-CNx20, made with a nitrogen flow rate of 20 sccm, shows the lowest residual amount of 234 μg for SiO2 ceramic particles, which is 81% less than that of the nontextured ta-CNx20. In conclusion, we provide design guidelines for nanotextured mold surfaces including the texturing pitch should be small enough for ceramic particles; the mold surface should be sufficiently hard; the lower the surface energy per unit area, the less residues of ceramic particles.

Durability of Super-Low Friction of Hydrogenated Carbon Nitride Coatings in High-Vacuum Environment

“…Diamond-like carbon (DLC) coatings are widely used in industrial applications because of their excellent friction properties, hardness, wear resistance, and thermal stability [1][2][3][4][5][6][7][8][9]. Furthermore, to improve these frictional and adhesion properties, many studies have been conducted on doping carbon structures with elements such as hydrogen, nitrogen, silicon, titanium, tungsten, and chromium [10][11][12].…”

Active control of Lubricant Flow Using Dielectrophoresis and Its Effect on Friction Reduction

“…In general, tribological surfaces of machine elements are designed to provide excellent performance with stable operation. For example, some surfaces are textured to reduce friction losses [1][2][3][4][5] and adhesion [6][7][8][9], and many products already have texturing surfaces. From the past to the present, hard coatings have been a very important technology in the industrial field due to their tribological performance as well as cost efficiency.…”

Influence of defects in sp2-bonded network of diamond-like carbon on silica scale adhesion in geothermal power plants

“…On the other hand, ta-C coatings contain many defects (droplet) due to the physical vapor deposition (PVD) method, which trigger the wear, cracking, and thermal degradation [22][23][24]. Murashima et al revealed that nitrogen-containing ta-C coatings have lower surface energy, resulting in few adhesion between ceramic particles and the ta-C coatings [25]. The coatings are known to develop unique tribolayer derived from oil additives, providing low friction and low wear tribo lms [26][27][28][29].…”

“…The carbonaceous structure is considered to easy to react with additive molecules on the surface, developing thick tribo lm or bring severe chemical wear of the coating [31][32][33][34][35][36][37]. About the adhesion on the surface it was reported that high hardness and low surface energy coatings was able to demonstrate low adhesion of ceramics particles [25]. In addition, it was revealed that the surface adhesion and tribological properties could be controlled by texturing and electrical charge [38][39][40][41][42][43][44][45].…”