Abstract
AbstractPolysilazanes 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.
Highlights
Elevated hardness, and excellent adhesion to many different substrates
We developed polysilazane-based coating systems containing different fillers applied onto aluminum substrates by a simple process, aiming at anti-adherent properties for easy release of carbon-fiber reinforced plastics (CFRP) parts, for example, from aluminum molds
The degree of crosslinking of the silazane-based coatings was analyzed by Fourier transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode (Tensor 27, Bruker Optik GmbH, Germany)
Summary
Elevated hardness, and excellent adhesion to many different substrates. 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. Compared to most organic polymers, polysilazanes have enhanced thermal and chemical stability, and higher the chemical composition, surface energy, and coating adhesion in dependhardness.[3] the coating adhesion is ency on the precursor type and crosslinking temperature. The anti-adherence properties are investigated by using a phenolic resin via pull-off adhesion, which is slightly reduced from 13 MPa usually stronger than of typical organic coatings, attributed to reactions with OH groups, present at the surface of most materials, leading to chemical bonding between coating and substrate.[4,5] Suitable polyfor uncoated aluminum to less than 10 MPa for HTTS coated substrates. Deposition 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 substrates must have a sufficient thermal stability to withstand
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