The Pulsed Ultrasonic Velocity Method for Determining Material Dynamic Elastic Moduli

Blessing, G. V.

doi:10.1520/stp24614s

Cited by 16 publications

(14 citation statements)

References 12 publications

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“…Young's modulus was measured for the infiltrated structures and for the bulk glass infiltrate material by means of a routine pulse-echo sonic technique (McSkimin, 1961;Blessing, 1988). In this technique, an ultrasonic pulse is sent into the material, and the time interval between successive echoes is monitored by means of a transducer.…”

Section: Methodsmentioning

confidence: 99%

Contact Damage Resistance and Strength Degradation of Glass-infiltrated Alumina and Spinel Ceramics

et al. 1999

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All-ceramic crowns are coming into widespread use because of their superior esthetics and chemical inertness. This study examines the hypothesis that glass-infiltrated alumina and spinel core ceramics are resistant to damage accumulation and strength degradation under representative oral contact conditions. Accordingly, Hertzian indentation testing with hard spheres is used to evaluate damage accumulation in alumina and spinel ceramics with different pre-form grain morphologies and porosities. Indentation stress-strain curves measured on fully infiltrated materials reveal a marked insensitivity to the starting pre-form state. The glass phase is shown to play a vital role in providing mechanical rigidity and strength to the ceramic structures. All the infiltrated ceramics show subsurface cone fracture and quasi-plastic deformation above critical loads P(C) (cracking) and P(Y) (yield), depending on sphere radius, with P(Y) < P(C). Strength degradation from accumulation of damage in Hertzian contacts above these critical loads is conspicuously small, suggesting that the infiltrated materials should be highly damage-tolerant to the "blunt" contacts encountered during mastication. Failure in the strength tests originates from either cone cracks ("brittle mode") or yield zones ("quasi-plastic mode"), with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Multi-cycle contacts at lower loads, but still above loads typical of oral function, are found to be innocuous up to 10(5) cycles in air and water, although contacts at 10(6) cycles in water do cause significant strength degradation. By contrast, contacts with Vickers indenters produce substantial strength losses at low loads, suggesting that the mechanical integrity of these materials may be compromised by inadvertent "sharp" contacts.

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Section: Methodsmentioning

confidence: 99%

Contact Damage Resistance and Strength Degradation of Glass-infiltrated Alumina and Spinel Ceramics

et al. 1999

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“…The evaluation of the sensor factors, listed in their estimated descending order of importance, has not been completed. Although the undetermined sensor factors in Table I prevent a decisive statement, from [2) and [5) we conclude that the velocity (due to material) variations might be allowed to consume the entire error budget.…”

Section: Ultrasonic Thickness Precisionmentioning

confidence: 88%

“…Material factors, assuming full density so that porosity is not a factor, include the texture, grain size, temperature, residual stress, frequency dispersion, and part surface roughness, Those factors, summarized below for their error contribution, were addressed in some detail in [5].…”

Section: Ultrasonic Thickness Precisionmentioning

confidence: 99%

In-Process Ultrasonic Thickness Metrology Applied to Steel Parts of Rotation

Blessing

Donmez

Eitzen

et al. 1991

Review of Progress in Quantitative Nondestructive Evaluation

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“…The sound velocity in longitudinal mode ( V L ) and in shear mode ( V S ) was measured. From these two wave speeds and the density (ρ) of the material, the elastic parameters were calculated with the use of the following equations:18, 19 The density was determined by Archimedes' method.…”

Section: Methodsmentioning

confidence: 99%

Effect of heat pressing on the mechanical properties of a mica‐based glass‐ceramic

Denry

Holloway

2004

J Biomed Mater Res

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Previous work has shown that heat pressing of mica-based glass-ceramics can lead to crystal alignment along the direction of pressing. The purpose of this study was to evaluate the effect of heat pressing on the fracture toughness of mica-based glass-ceramics. Glass rods (12 x 60 mm) were prepared by melting the glass composition at 1400 degrees C for 2 h. Ingots (12 x 12 mm; n = 5) and discs (12 x 1.5 mm; n = 10) were cut from the rods. The discs were heat treated to simulate heat pressing and served as controls. A machinable mica-based glass- ceramic (Dicor MGC) also served as control. Bar-shaped wax patterns (2 x 4 x 22 mm) were invested and heat pressed at 875 degrees C. The elastic constants were determined with the use of the pulsed ultrasonic velocity method. The fracture toughness was measured by the indentation strength technique. The degree of texture was assessed qualitatively by X-ray diffraction and quantitatively on digital SEM micrographs. The results showed that the mean fracture toughness of the heat-pressed specimens (1.96 +/- 0.19 MPa. m(0.5)) was significantly higher than that of the heat-treated controls (1.51 +/- 0.21 MPa. m(0.5)) or the proprietary mica glass-ceramic (Dicor MGC; 1.66 +/- 0.04 MPa. m(0.5)) (p <.001). It was concluded that heat pressing led to a significant increase in fracture toughness in mica glass-ceramics because of crystal alignment along the direction of pressing.

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The Pulsed Ultrasonic Velocity Method for Determining Material Dynamic Elastic Moduli

Cited by 16 publications

References 12 publications

Contact Damage Resistance and Strength Degradation of Glass-infiltrated Alumina and Spinel Ceramics

Contact Damage Resistance and Strength Degradation of Glass-infiltrated Alumina and Spinel Ceramics

In-Process Ultrasonic Thickness Metrology Applied to Steel Parts of Rotation

Effect of heat pressing on the mechanical properties of a mica‐based glass‐ceramic

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