Tribological wear analysis and numerical lifetime prediction of glassy carbon tools in fused silica molding

Dukwen, Julia; Friedrichs, Marcel; Liu, Gang; Tang, Minjie; Dambon, Olaf; Klocke, Fritz

doi:10.1016/j.wear.2016.07.011

Cited by 20 publications

(16 citation statements)

References 9 publications

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“…As far as viscoelastic characterization is concerned, there are currently several methods that are based on the creep behavior of glass, such as compression creep test (CCT), [14][15][16][17] bending creep test, 18,19 and indentation creep test. As far as viscoelastic characterization is concerned, there are currently several methods that are based on the creep behavior of glass, such as compression creep test (CCT), [14][15][16][17] bending creep test, 18,19 and indentation creep test.…”

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confidence: 99%

“…Generally, glass exhibits both viscous and elastic characteristics (ie viscoelasticity) when undergoes deformation in the transition region, with the quintessential time-dependent behaviors of creep and relaxation. As far as viscoelastic characterization is concerned, there are currently several methods that are based on the creep behavior of glass, such as compression creep test (CCT), [14][15][16][17] bending creep test, 18,19 and indentation creep test. [20][21][22][23] Among them the most commonly used is CCT that can be handily implemented on hightemperature testing machines without complex specimen or fixture preparations.…”

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confidence: 99%

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A comprehensive study on frictional dependence and predictive accuracy of viscoelastic model for optical glass using compression creep test

Luo

Zhang

et al. 2019

J Am Ceram Soc

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Compression creep tests (CCTs) have been widely used in phenomenological characterization of viscoelastic materials such as glasses. However, disturbed by specimen‐tool interface friction, the real stress‐strain data regarding the pure viscoelastic deformation are frequently misestimated in conventional CCTs, causing decreased accuracies of the derived viscoelastic parameters. This study proposes a comprehensive CCT‐based approach to develop a viscoelastic model with weakened frictional disturbance and enhanced predictive accuracy. An integrated calculation procedure is first built to mathematically characterize the frictional and viscoelastic behaviors of glass during compression. Uniaxial CCTs of a typical borosilicate glass (L‐BAL42) are then performed at varied frictional conditions. The quantified coefficients of interface friction indicate that a minor frictional disturbance is achieved when Nickel foils are used as interfacial layers, whereby a more realistic viscoelastic constitutive relation of the glass is derived. The obtained frictional and viscoelastic constants are further incorporated into computational modeling of the CCT and precision molding processes. The demonstrated consistencies between the simulated and measured results (creep displacement and molding force) suggest that, by technically slashing the interface friction and theoretically correcting the friction‐involved stress in CCTs, the frictional disturbance to experimental stress‐strain data can be effectively weakened, and a viscoelastic model of enhanced predictive accuracy can be thus developed.

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confidence: 99%

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confidence: 99%

A comprehensive study on frictional dependence and predictive accuracy of viscoelastic model for optical glass using compression creep test

Luo

Zhang

et al. 2019

J Am Ceram Soc

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“…The publications of Dukwen et al [19,27] form the foundation of the approach to put Fused Silica moulding into an industrial context. This research dealt with preliminary investigations of the wear behaviour in Fused Silica forming by Precision Glass Moulding.…”

Section: Discussionmentioning

confidence: 99%

Influence of Glassy Carbon Surface Finishing on Its Wear Behavior during Precision Glass Moulding of Fused Silica

et al. 2019

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Laser technology has a rising demand for high precision Fused Silica components. Precision Glass Moulding (PGM) is a technology that can fulfil the given demands in efficiency and scalability. Due to the elevated process temperatures of almost 1400 °C and the high mechanical load, Glassy Carbon was qualified as an appropriate forming tool material for the moulding of Fused Silica. Former studies revealed that the tools’ surface finishing has an important influence on wear behaviour. This paper deals with investigation and analysis of surface preparation processes of Glassy Carbon moulds. In order to fulfil standards for high precision optics, the finishing results will be characterised by sophisticated surface description parameters used in the optics industry. Later on, the mould performance, in terms of wear resistance, is tested in extended moulding experiments. Correlations between the surface finish of the Glassy Carbon tools and their service lifetime are traced back to fundamental physical circumstances and conclusions for an optimal surface treatment are drawn.

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“…Second, by fine polishing, the surfaces of the mold pair is mirror‐like with the roughness of R a = 2 nm . Such ultraprecision mold surface enables a small friction coefficient at the glass‐mold interface, below

0.1

. As indicated in the previous works, the low friction coefficient is essential to minimize the error that leads to the impurity of the viscoelastic properties derived from the creep experiments due to the frictional deformation of the glass.…”

Section: Conventional Characterization Of Thermo‐viscoelastic Materiamentioning

confidence: 92%

“…31 Such ultraprecision mold surface enables a small friction coefficient at the glass-mold interface, below 0.1. 32 As indicated in the previous works, 5,26,28 the low friction coefficient is essential to minimize the error that leads to the impurity of the viscoelastic properties derived from the creep experiments due to the frictional deformation of the glass. Figure 1 exhibits the polished glassy-carbon molds and the glass specimen used for the creep experiments.…”

Section: Methodsmentioning

confidence: 98%

Modeling of thermo‐viscoelastic material behavior of glass over a wide temperature range in glass compression molding

Grunwald

Bergs

2020

J Am Ceram Soc

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In glass compression molding, most current modeling approaches of temperature‐dependent viscoelastic behavior of glass materials are restricted to thermo‐rheologically simple assumption. This research conducts a detailed study and demonstrates that this assumption, however, is not adequate for glass molding simulations over a wide range of molding temperatures. In this paper, we introduce a new method that eliminates the prerequisite of relaxation functions and shift factors for modeling of the thermo‐viscoelastic material behavior. More specifically, the temperature effect is directly incorporated into each parameter of the mechanical model. The mechanical model parameters are derived from creep displacements using uniaxial compression experiments. Validations of the proposed method are conducted for three different glass categories, including borosilicate, aluminosilicate, and chalcogenide glasses. Excellent agreement between the creep experiments and simulation results is found in all glasses over long pressing time up to 900 seconds and a large temperature range that corresponds to the glass viscosity of log (η) = 9.5 – 6.8 Pas. The method eventually promises an enhancement of the glass molding simulation.

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Tribological wear analysis and numerical lifetime prediction of glassy carbon tools in fused silica molding

Cited by 20 publications

References 9 publications

A comprehensive study on frictional dependence and predictive accuracy of viscoelastic model for optical glass using compression creep test

A comprehensive study on frictional dependence and predictive accuracy of viscoelastic model for optical glass using compression creep test

Influence of Glassy Carbon Surface Finishing on Its Wear Behavior during Precision Glass Moulding of Fused Silica

Modeling of thermo‐viscoelastic material behavior of glass over a wide temperature range in glass compression molding

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