Polysilazane‐Based Coatings with Anti‐Adherent Properties for Easy Release of Plastics and Composites from Metal Molds

Abstract

Polysilazanes are excellent coating materials, because of their self‐crosslinking in air at low temperatures, high chemical and thermal stability, elevated hardness, and excellent adhesion to many different substrates. Therefore, coatings of two chemically different polysilazanes (crosslinked Durazane 1800 (HTTS)/perhydropolysilazane (PHPS)) are deposited by either dip or spray coating and crosslinked at 200 or 300 °C in air to investigate the chemical composition, surface energy, and coating adhesion in dependency on the precursor type and crosslinking temperature. The silazane HTTS possesses a higher amount of nonpolar organic groups resulting in a lower surface free energy. The anti‐adherence properties are investigated by using a phenolic resin via pull‐off adhesion, which is slightly reduced from 13 MPa for uncoated aluminum to less than 10 MPa for HTTS coated substrates. The addition of different amounts of poly(tetrafluoroethylene) (PTFE) particles causes a remarkable reduction of the surface free energy leading to a strongly reduced pull‐off adhesion of less than 4 MPa of the phenolic resin from the HTTS/PTFE coated substrates. The anti‐adherent properties remain even after repeated pull‐off tests. Because of the excellent properties, the HTTS/PTFE coatings are a very suitable system for easy mold release of plastic parts from metal molds and to replace commercial nonstick PTFE coatings.

Mechanical Properties of Protective Coatings against Marine Fouling: A Review

“…The development of antifouling coatings with hydrophobic character was also focused in recent years on “non-conventional” polymers. Barroso et al [ 65 ] investigated coatings based on pure polysilazane or loaded with poly(tetrafluoroethylene) (PTFE) particles. Such systems possess a higher amount of nonpolar organic groups resulting in a low surface free energy that was further lowered by the addition of PTFE fillers.…”

Evaluation of mechanical properties and hydrophobicity of room‐temperature, moisture‐curable polysilazane coatings

“…A similar tendency describing the change in contact angle with curing time for all coatings can be observed. Consider the D1500-rc coating as an example, the hydrophobic groups, such as, Si H 16 and Si CH 3 23 result in a hydrophobic surface with a contact angle of 94.6 ± 0.5 .…”

“…The adhesion of polysilazane to most surfaces is known to be good due to the chemical reactions of Si H, Si NH groups with the OH groups and the adsorbed water molecules on surface, which form subsequently oxygen bridges between the polysilazane coating and the substrate. 16,39,40 Figure 9 shows the optical microscopy images of five polysilazane coatings cured after 1, 3, and 7 days and with the standard cross-cut tape test being performed. According to the DIN EN ISO 2409, coatings are classified from Gt 0 (best adhesion, without any detachment of the coating after the test) to Gt 5 (worst adhesion, detachment of the coating >65% of the tested area).…”

“…In recent years, low temperature curing of polysilazane-based coatings has been studied for applications, such as, gas barrier, 13 marine anti-fouling coating, 14 anti-graffiti coating for public transportation, 15 and anti-adherent coating for demolding. 16 Polysilazane coatings can be cured and converted into thermoset polymeric coatings by several types of treatment, such as, thermal crosslinking, 17 UV radiation, 18 O 2 plasma treatment, 19 and moisture curing by hydrolysis and condensation reactions. 20 Studies have been undertaken to explore in detail the low-temperature curing behavior and mechanism of polysilazane coatings.…”

Biological evaluation of preceramic organosilicon polymers for various healthcare and biomedical engineering applications: A review

“…They belong to the group of biomaterials used in prosthetic devices such as implant for breast enlargement, tissue augmentation and for treatment of hydrocephalus 49 . Although few experiments concerning the corrosion studies of polysilazane‐based surface coatings have indicated an excellent corrosion and oxidation resistance and more hydrophobicity, the in vitro performance of such coatings for biomedical applications are still far from being concluded 50,51 . Hoffmann and coworkers 52 studied two types of coatings, that is, sol–gel coatings (TiO 2 ) and precursor‐derived coatings in the system SiCN (Ti) on medical alloys (Ti6Al4V and Co28Cr6Mo alloy) for their biocompatibility and hindrance to toxic ions release from metal alloys.…”