High-shear-rate optical rheometer

Mriziq, Khaled S.; Dai, H. J.; Dadmun, Mark; Jellison, G. E.; Cochran, H. D.

doi:10.1063/1.1711145

Cited by 21 publications

(10 citation statements)

References 12 publications

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“…However, these techniques do not closely imitate the centripetal motion of the polishing process, and the caking or coating of particles on the walls of the instrument often disrupts the integrity of the rheological measurements (not to mention the limited range of data collected with a single sample loading). High shear experiments can also be performed with a parallel-plate geometry on a rotational rheometer (Kelly et al 2009;Pipe et al 2008;Mriziq et al 2004Mriziq et al , 2007. When working with the parallel-plate setup, two conditions can be exploited for high shear measurements: (1) operate the rheometer near the upper torque limit by rotating the geometry at high velocities and/or (2) decrease the gap spacing between the two instrument plates.…”

Section: Introductionmentioning

confidence: 99%

Shear thickening of chemical mechanical polishing slurries under high shear

et al. 2012

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Chemical mechanical polishing (CMP) is a fundamental technology used in the semiconductor manufacturing industry to polish and planarize electronic materials. During the high shear (≥1,000,000 s −1 ) polishing process, it is hypothesized that individual slurry particles begin to interact and collide with one another forming large agglomerates (≥0.5 μm). These agglomerates are suspected of causing defects such as scratches or gouges during polishing, which costs the semiconductor industry billions of dollars annually. We have developed a method for investigating the shear thickening behavior of fumed silica slurries (20-34 wt.%) under high shear using a parallel-plate geometry in a conventional rotating rheometer. The CMP slurries displayed irreversible thickening at shear rates exceeding 10,000 s −1 . Viscous heating and sample evaporation are shown to be inconsequential to the witnessed shear thickening behavior. Also, the observed thickening is not a result of a critical rheometer speed, as the thickening was independent of the experimental gap height. In agreement with previous work, the slurries thickened at lower shear rates as silica concentration was increased. The shear thickening of the fumed N. Crawford · M. Liberatore (B) silica slurries is truly shear-induced, and therefore, the thickening of CMP slurries can be examined using a rotational rheometer at small gap heights (≤100 μm).

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Section: Introductionmentioning

confidence: 99%

Shear thickening of chemical mechanical polishing slurries under high shear

et al. 2012

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“…In this case the oscillator strengths P 1 and P 3 are approximately proportional to the square of the refractive index in the visible region of frequency [43]. Since the refractive index for the lubricant is a function of the shear stress through orientation of chain subsituents [52], shear stress could increase the adhesion stress. Typically the friction increases by 1.59 as the pressure is increased above the TDP, Fig.…”

Section: Frictional Energy Dissipationmentioning

confidence: 98%

Dynamics in the Bridged State of a Magnetic Recording Slider

2008

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A novel region of tribological interaction is explored by inducing near contact between the magnetic recording slider and disk. In this study, we performed frictional measurements over a wide range of subambient air pressure and disk rotation rate. Since the slider is supported over the disk by an air bearing, it has been found that cycling from ambient to subambient and then back up to ambient pressure over several minutes of time forms a frictional hysteresis loop. The high-friction branch of the loop, referred to as the bridged state, is characterized by an average frictional displacement and resonant vibration of the suspension mount assembly. The bridged state is currently employed for accelerated wear testing of magnetic slider/disk/lubricant systems. Future magnetic recording systems designed to operate at increasingly lower physical spacing will need to take into account these frictional forces which accompany the incipient contact between the lubricated disk and slider with finite surface roughness. A single degree of freedom model is solved to determine the equivalent dynamic friction force on the slider as an impulse series with random impulse frequency and amplitude from the measured frictional displacement in the bridged state. The mean slider-disk spacing in the bridged state is derived from the experimental friction force, the spacing probability density function, and the adhesion stress from the Lifshitz model for dispersion interaction energy.

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“…While different techniques have been developed to study the rheology of fluids under high shear or in microscale confinement, probably the most accessible route is the adaptation of commercially available rheometers. Reports on utilizing rotary parallel-plate rheometers operating at micrometer gaps go back to the early 80's [21,47,48] and the idea has been revisited frequently due to the simplicity of this approach and the ongoing technical improvements of commercially available rotational rheometers [24,26,37,65,75]. The different approaches can be categorized in two groups: identifying the possible errors that will arise when operating parallel-plates at micrometer gap separations (and correcting data for these errors and/or identifying the experimental limits), and secondly, improving the shear geometries in order to minimize the errors.…”

Section: Adaptations To a Conventional Rotational Rheometermentioning

confidence: 99%

The dark side of microrheology: Non-optical techniques

Vleminckx

Clasen

2014

Current Opinion in Colloid & Interface Science

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Microrheology probes the mesoscale between bulk rheology, which provides an integral sample response, and nanorheology, which refers to a local response at a molecular confinement level. The term 'microrheology' is often used to refer to optical particle tracking methods that measure a local response of a sample. In contrast to this, non-optical microrheology techniques generally allow two different effects to be studied: actual confinement effects on the rheology and boundary effects such as slip. Investigating the mesoscale range has additional advantages such as the possibility to perform measurements with small sample volumes and at high shear rates. This review bundles the wide array of non-optical techniques into five categories: adaptations to a conventional rotational rheometer, sliding plate rheometry on a micrometer scale, microfluidics, piezo vibrators and radial channel flows. The concept of each set of techniques is described, together with their operational window and examples of recent studies.

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High-shear-rate optical rheometer

Cited by 21 publications

References 12 publications

Shear thickening of chemical mechanical polishing slurries under high shear

Shear thickening of chemical mechanical polishing slurries under high shear

Dynamics in the Bridged State of a Magnetic Recording Slider

The dark side of microrheology: Non-optical techniques

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