Design of Protective Coatings for Glass Lens Molding

Jeng, Kung; Chien, H.H.; Chuan, W.H.; Chao, Choung Lii; Hwang, K.C.

doi:10.4028/0-87849-458-8.655

Cited by 5 publications

(8 citation statements)

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“…While Pt is corrosion resistant in most oxidizing environments, alloying with Ir drastically improves the mechanical properties rendering the alloy suitable for applications which demand high strength at elevated temperatures in corroding environments 1 , 4 . These alloys are thus employed in chemically demanding applications for example as electrode materials in fuel cells 5 , 6 , as catalyst in hydrogenation applications 7 and organic chemical synthesis 8 , 9 , as protective coating for precision glass molding (PGM) applications 10 – 13 , as well as implantable electronic devices 14 , as a coronary stent 15 , 16 and for many other medical applications 17 .…”

Section: Introductionmentioning

confidence: 99%

Metastable phase formation of Pt-X (X = Ir, Au) thin films

Saksena

Chien

Chang

et al. 2018

Sci Rep

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The dependence of phase formation and mechanical properties on the chemical composition has been investigated for Pt-Ir and Pt-Au combinatorial thin films. The formation of a single, metastable Pt-Ir solid solution has been observed for all experimental compositions and temperatures. Upon Ir addition to Pt the experimentally determined changes in lattice parameter and Young’s modulus display rule of mixture behavior which is in good agreement with our ab initio data. Whereas, in the Pt-Au system, the single metastable solid solution decomposes into two phases as the growth temperature is raised to ≥600 °C. The lattice parameters in the dual phase region are independent of chemical composition. The substrate temperature and chemical composition dependent phase formation in Pt-Ir and Pt-Au thin films can be rationalized based on CALPHAD (CALculation of PHAse Diagrams) results combined with estimations of the activation energy required for surface diffusion: The metastable phase formation during film growth is caused by kinetic limitations, where Ir atoms (in Pt-Ir) need to overcome an up to factor 6 higher activation energy barrier than Au (in Pt-Au) to enable surface diffusion.

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Section: Introductionmentioning

confidence: 99%

Metastable phase formation of Pt-X (X = Ir, Au) thin films

Saksena

Chien

Chang

et al. 2018

Sci Rep

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“…The PtIr layer itself exhibits very good anti-sticking property against hot glass. However, as shown by previous studies [12,29,30], the newly formed oxide scale will enhance the chemical interaction between the coating and the glass blank, and lead to the adhesion of glass on the mold surface. i.e.…”

Section: Specimen Characterizationmentioning

confidence: 84%

“…To enhance the adhesion strength of the PtIr coatings on the cemented tungsten carbide main part, an adhesion layer is also applied, which is normally a pure metallic thin film. Most frequently used ones are Cr and Ni [12,17,23].…”

Section: Introductionmentioning

confidence: 99%

PtIr protective coating system for precision glass molding tools: Design, evaluation and mechanism of degradation

Friedrichs

Peng

Grunwald

et al. 2020

Surface and Coatings Technology

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During Precision Glass Molding (PGM), the molding tools have to withstand severe thermochemical and thermo-mechanical loads cyclically. To protect their high-quality optical surface against degradation and increase their service lifetime, protective coatings are applied on the molding tools. In this work, we designed four different PtIr protective coating systems, where the thickness of the PtIr layer and the adhesion layer were varied. Their lifetimes were evaluated and compared using an in-house built testing bench. Among all the studied coating systems, the protective coating, which consists of a 600-nm-thick PtIr layer and a 20-nm-thick Cr adhesion layer, showed the best durability with the longest lifetime. To understand the degradation mechanism of the coating during actual engineering production, an industrial PGM machine was used and emulation PGM tests were conducted. Detailed sample characterization was performed using an array of complementary techniques including white light interferometry (WLI), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), scanning transmission electron microscopy (STEM) and atom probe tomography (APT).Phenomena such as interdiffusion, oxidation, coating spallation and glass sticking on the coating were observed and are discussed in the context of optimization of the coating's performance and durability.

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“…Pressprozess wird unter Schutzgasatmosphäre durchgeführt [9]. [10][11][12][13][14]. Verschiedene PVD-Beschichtungen wurden für den Einsatz beim PGM untersucht.…”

Section: Discussionunclassified

“…Verschiedene PVD-Beschichtungen wurden für den Einsatz beim PGM untersucht. Hierzu zählen Edelmetallschichten aus Platin-Iridium, Iridium und Rhenium-Iridium, die aufgrund einer geringen chemischen Reaktivität mit anderen Elementen eingesetzt und überwiegend im asiatischen Raum für industrielle Anwendungen verwendet werden [11][12][13][14]. Zudem gibt es kohlenstoffbasierte Beschichtungen (dia-mond-like carbon, DLC) und nitridische Hartstoffschichten.…”

Section: Discussionunclassified

PVD‐Schutzschichten für Werkzeuge des Präzisionsblankpressens

Bobzin¹,

Brögelmann²,

Kruppe³

et al. 2019

Vak Forsch Prax

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Summary PVD protective coatings for precision molding tools Precision glass molding (PGM) is a replicative hot forming process for the production of complex optical components, such as aspherical lenses for digital and mobile phone cameras or optical elements for laser systems. The efficiency and thus also the profitability of the PGM depend on the unit price per pressed component, which correlates primarily with the service lifetime of the pressing tools. To increase tool lifetime, the tool surfaces are coated with protective coatings based on precious metals or carbon using physical vapour deposition (PVD). The PVD coating technology enables the deposition of thin coatings, which also follow more complex surface geometries and achieve a high surface quality. PVD coatings are also commonly used to protect tools from wear and corrosion. This paper presents two chromium‐based nitride hard coatings produced by an industrial PVD unit and investigated for their applicability for PGM. Two different coating architectures were implemented, on the one hand a single coating chromium aluminium nitride (Cr,Al)N coating and on the other hand a nanolaminar CrN/AlN coating with alternating layers of chromium nitride and aluminium nitride. The latter is a coating consisting of hundreds of nano‐layers, only a few nanometers thick. Both coatings, (Cr,Al)N and CrN/AlN, each have a thickness of s ∼ 300 nm in order to follow the tool contour as closely as possible. The properties of the coating systems, which are of particular relevance for PGM, are considered. These include on the one hand the adhesion of glass, the roughness and topography of the surface and the adhesion between the coating and the tool material. In addition, the barrier effect of the coatings against diffusion of oxygen was investigated. In order to reproduce the thermal boundary conditions of the PGM, thermocyclic aging tests are performed and their influence on the different properties is described.

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Design of Protective Coatings for Glass Lens Molding

Cited by 5 publications

References 0 publications

Metastable phase formation of Pt-X (X = Ir, Au) thin films

Metastable phase formation of Pt-X (X = Ir, Au) thin films

PtIr protective coating system for precision glass molding tools: Design, evaluation and mechanism of degradation

PVD‐Schutzschichten für Werkzeuge des Präzisionsblankpressens

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