Fracture resistance of ceramics: Base diagram and R-line

Gogotsi, G. A.

doi:10.1007/s11223-006-0039-0

Cited by 23 publications

(28 citation statements)

References 23 publications

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“…It appears that these quantities are in a linear relationship (Fig. 4), called the baseline [15]. This line indicates that the two essentially different test methods make equivalent assessments of fracture resistance.…”

Section: Description Of Testsmentioning

confidence: 87%

“…[15], a specimen bonded to a photographic glass was placed on the two-axis table of a СeramTest unit (Gobor Ltd.) mounted on a universal testing machine. To chip the edge, a standard diamond Rockwell indenter (Gilmore Diamond Tools, Inc.) with spherical tip of radius of 200 μm fixed in the load rod of the test unit was used.…”

Section: Description Of Testsmentioning

confidence: 99%

“…Fracture toughness and fracture resistance were measured on the same specimen to avoid any doubt that the materials tested under different conditions were different. Based on a great amount of statistically reliable test data, a method for edge fracture (EF) tests with a Rockwell indenter was developed [15]. Its major feature is an original analysis of edge-chipping data and a mechanicophysical approach to the problem.…”

Section: Description Of Testsmentioning

confidence: 99%

“…3). Fracture resistance value is calculated as follows [15]: values, determined on the same specimens of ordinary homogeneous single-phase ceramics similar in mechanical behavior to the LEFM model material. It appears that these quantities are in a linear relationship (Fig.…”

Section: Description Of Testsmentioning

confidence: 99%

“…In Ref. [15], it was proposed to describe this effect by plotting fracture resistance r F versus fracture distance L (R-lines shown in Fig. 6).…”

Section: Analysis Of Test Datamentioning

confidence: 99%

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Edge chipping resistance of ceramics: Problems of test method

Gogotsi

2013

J Adv Ceram

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An unconventional method for determining the fracture resistance of brittle materials is discussed. This method employs a conical indenter to chip the rectangular edge of the specimen. Particular features of the method are the use of small specimens and the evaluation of the resistance of materials to the nucleation, initiation and propagation of a crack. It is shown that this method is somewhat similar to the Hertzian fracture method and to the way that early man selected stones to make tools and weapons. Measured data of the fracture resistance of ceramics is presented. It is confirmed that if a ceramic material is similar to the model material of linear elastic fracture mechanics (LEFM), then those fracture resistance values are directly proportional to the critical stress intensity factors (baseline). For elastic and inelastic ceramics, R-lines characterizing the fracture resistance to crack growth are plotted. It is shown that proportionality lines (edge chipping resistance versus critical stress intensity factor) may be straight lines for ceramics with similar structure (such as Y-TZP and Mg-PSZ). The effect of rounding of the conical indenter tip (10-800 µm) on chip scar shape is indicated. Other aspects in the fracture behavior of ceramics during edge chipping are also analyzed. The advantages and disadvantages of the method are discussed. Further studies in this mechanico-physical research area are suggested.

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Section: Description Of Testsmentioning

confidence: 87%

Section: Description Of Testsmentioning

confidence: 99%

Section: Description Of Testsmentioning

confidence: 99%

Section: Description Of Testsmentioning

confidence: 99%

“…In Ref. [15], it was proposed to describe this effect by plotting fracture resistance r F versus fracture distance L (R-lines shown in Fig. 6).…”

Section: Analysis Of Test Datamentioning

confidence: 99%

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Edge chipping resistance of ceramics: Problems of test method

Gogotsi

2013

J Adv Ceram

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On the mechanics of surface and side-wall chipping from line-wedge indentation

Chai

Ravichandran

2007

Int J Fract

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Chipping in glass plates from line-wedge contact loading is studied as function of the wedge's subtended angle 2β, its inclination angle φ, and the distance h from a corner having a subtended angle 90 • −θ . A brittle-fracture analysis in conjunction with the FEM technique is used to elucidate the role of geometric variables on chip morphology and chipping load. Closedform relations are developed for the latter by invoking the principle of geometric similarity and taking into consideration the details of contact forces transmitted to the crack mouth. The fracture progresses stably until surface effects alter the crack trajectory to form a chip. The latter conclusively occurs from the top surface if φ > β while from the side wall if φ < β. The fracture load for top-surface spalling scales with w 1/2 , where w is the indentation depth, and it monotonically declines with the offset angle ψ ≡ φ − β, that for side-wall chipping scales with h 1/2 and it is little sensitive to φ for moderate values of θ . In both the cases, the chipping load increases with β. The results may provide insight into the mechanics of chipping in more complex anthropological, tribological, geological and biomedical applications, including flint-knapping, dental Herzl Chai-On leave, School of Mechanical Engineering, fracture, grinding and polishing and common cutting and machining operations.

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Determination of the critical stress intensity factor of glass under conditions of elastic contact by the dynamic indentation method

Kren

2009

Strength Mater

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A. P. Kren'UDC 539.3The possibility of determining the fracture toughness under conditions of elastic contact during dynamic indentation is analyzed. Procedures are proposed for estimating the critical stress intensity factor from the parameters of initiating cracks and directly from the contact force versus indentation depth curve during dynamic indentation.To test the fracture toughness (crack growth resistance) of brittle materials (glass, ceramics, etc.) is an urgent and complex problem. This is due, first of all, to the fact that the standard test methods [1, 2] and recently proposed [3,4] measurement procedures are rather difficult to implement. Difficulties arise both during the manufacture of test specimens and directly in the process of crack formation. In order to test this, the method of estimating the fracture toughness from the results of measuring sizes of initiating radial cracks in the material under static indentation is widely used [5]. A Vickers hardness tester (with a diamond pyramid indenter), the so-called indentation fracture (IF) method, is used as a basic tool [6,7]. The IF-method, though widely used, has still a number of limitations, of which the main ones are the accuracy of determining crack size in optically opaque materials [8] and cumbersome equipment prohibiting the testing directly on the object. At the same time, glass and ceramics are widely used in various branches of industry, such as the aerospace and automobile industry, the building and construction industry, etc. On this basis, the development of the method that would enable fast evaluating the fracture toughness using simple and commonly available equipment is urgent.The dynamic indentation method that can be implemented by recording the whole process of pressing an indenter has a greater opportunity than the IF-method [9]. The use of this method for estimating the fracture toughness of brittle materials has undoubtedly a number of advantages. Noteworthy is the difference in the deformation pattern manifested during indentation at different indenter velocities and radius of curvature of the indenter tip. Thus, according to [10], during indentation of glass by a flat die or a spherical indenter with a large radius of curvature, the fracture pattern is predominantly brittle, whereas during indentation by a pyramid, cone or a spherical indenter with a small radius of curvature, the character of fracture becomes more complex since a large part of the energy is spent on the plastic deformation. The critical indenter radius defines the boundary beyond which the hardness H is the governing factor of the material behavior during indentation. With the increase in the indenter radius, the fracture is defined by the material fracture toughness that can be characterized by the critical stress intensity factor (SIF) K c 1 . Here, an increase in the rate of loading is a guaranteed prerequisite for the Hertzian fracture. These statements testify that the creation of the condition for brittle fracture (impact indentation) seems to be mo...

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Fracture resistance of ceramics: Base diagram and R-line

Cited by 23 publications

References 23 publications

Edge chipping resistance of ceramics: Problems of test method

Edge chipping resistance of ceramics: Problems of test method

On the mechanics of surface and side-wall chipping from line-wedge indentation

Determination of the critical stress intensity factor of glass under conditions of elastic contact by the dynamic indentation method

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