SRBSN Material Development for Automotive Applications

Mikijelj, Biljana; Mangels, J. A.

doi:10.1002/9783527612765.ch65

Cited by 7 publications

(6 citation statements)

References 3 publications

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“…The manufacturer reported the fracture toughness as between 5.5 and 6.5 MPa m 1/2 . 17 New results using the three methods in ASTM standard C 1421-99 18 (single-edge pre-cracked beam, chevron-notched beam, and surface crack in flexure) produced very consistent results from 5.3 to 5.6 MPa m 1/2 on average. 14 Standard rectangular bend specimens of size 3 mm × 4 mm × 45 mm were sliced and ground from these blanks.…”

Section: Materials and Measurementsmentioning

confidence: 63%

“…K R values of 5-6 MPa m 1/2 were found as reported earlier from the conventional chevron-notched beam, single-edged precracked beam and surface crack in flexure methods. 14,17,18 In these measurements the steep increase of the R-curve is not visible. A starting point of the R-curve at K R ≈ 4.7 MPa m 1/2 is visible which is in clear contrast to the K I0 ≈ 1.7 MPa m 1/2 found from COD evaluation.…”

Section: Computation Of the R-curvementioning

confidence: 86%

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Bridging stresses in sintered reaction-bonded Si3N4 from COD measurements

Fett

Münz

Njiwa

et al. 2005

Journal of the European Ceramic Society

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Section: Materials and Measurementsmentioning

confidence: 63%

Section: Computation Of the R-curvementioning

confidence: 86%

Bridging stresses in sintered reaction-bonded Si3N4 from COD measurements

Fett

Münz

Njiwa

et al. 2005

Journal of the European Ceramic Society

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“…Schematic diagram of (a) median half-penny crack and (b) Palmqvist crack system, where: l is the surface crack length; 2c or 2a is the length of the diamond indent; c is the centre of the diamond to the end of the crack tip; Pc is the load impact; and lc is an interior crack Ponton and Rawlings [10] state that the equation given by Kelly et al [31] suggested that equation (10) 3 , with a surface roughness of 1.58 mm (as received from the manufacturer). This was to reduce the laser beam reflection, as the well-polished, shinier surfaces of the ceramic would reduce beam absorption.…”

Section: Selection Of Equations For Calculating the K 1cmentioning

confidence: 99%

“…Engineering ceramics offer exceptional mechanical properties, which allows them to replace the more conventional materials currently used for high-demanding applications. The engineering applications of various advanced ceramics have been amply demonstrated [1][2][3][4][5][6][7]. The Vickers indentation method, applicable for calculating the K 1c of the Si 3 N 4 ceramic, has been employed by Shukla [8] using the methodology derived by Ponton and Rawlings [9,10].…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness of a Zirconia Engineering Ceramic and the Effects Thereon of Surface Processing with Fibre Laser Radiation

Shukla

Lawrence

2010

Proceedings of the Institution of Mechanical Engineers, Part B:

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Vickers hardness indentation tests were employed to investigate the near-surface changes in the hardness of a fibre laser-treated and an as-received ZrO 2 engineering ceramic. Indents were created using 5, 20, and 30 kg loads to obtain the hardness. Optical microscopy, white-light interferometry, and a coordinate measuring machine were then used to observe the crack lengths and crack geometry. Palmqvist and half-penny median crack profiles were found, which dictated the selection of the group of equations used herein. Computational and analytical approaches were then adapted to determine the K 1c of ZrO 2 . It was found that the best applicable equation was:1/2 (P/c 3/2 ), which was confirmed to be 42 per cent accurate in producing K 1c values within the range of 8 to 12 MPa m 1/2 for ZrO 2 . Fibre laser surface treatment reduced the surface hardness and produced smaller crack lengths in comparison with the as-received surface. The surface crack lengths, hardness, and indentation loads were found to be important, particularly the crack length, which significantly influenced the end K 1c value when K 1c ¼ 0.016 (E/H) 1/2 (P/c 3/2 ) was used. This is because, the longer the crack lengths, the lower the ceramic's resistance to indentation. This, in turn, increased the end K 1c value. Also, the hardness influences the K 1c , and a softer surface was produced by the fibre laser treatment; this resulted in higher resistance to crack propagation and enhanced the ceramic's K 1c . Increasing the indentation load also varied the end K 1c value, as higher indentation loads resulted in a bigger diamond footprint, and the ceramic exhibited longer crack lengths.

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“…Expensive machining processes, including the use of hot press, are additionally required when the products have a two-dimensional shape. 1) Sintered reaction bonded silicon nitride (SRBSN) is fabricated by the mixing of Si powder with sintering additives and the subsequent shaping, nitridation, and sintering of the powder compact. This material has several advantages such as the low price of Si powder and the small shrinkage compared to that of conventional Si 3 N 4 ; these advantages make this material particularly attractive for the production of relatively large components.…”

Section: Introductionmentioning

confidence: 99%

Densification of Reaction Bonded Silicon Nitride with the Addition of Fine Si Powder - Effects on the Sinterability and Mechanical Properties

Lee¹,

Cho²,

Park³

et al. 2013

Journal of the Korean Ceramic Society

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The densification behavior and strength of sintered reaction bonded silicon nitrides (SRBSN) that contain Lu 2 O 3-SiO 2 additives were improved by the addition of fine Si powder. Dense specimens (relative density: 99.5%) were obtained by gas-pressure sintering (GPS) at 1850 o C through the addition of fine Si. In contrast, the densification of conventional specimens did not complete at 1950 o C. The fine Si decreased the onset temperature of shrinkage and increased the shrinkage rate because the additive helped the compaction of green bodies and induced the formation of fine Si 3 N 4 particles after nitridation and sintering at and above 1600 o C. The amount of residual SiO 2 within the specimens was not strongly affected by adding fine Si powder because most of the SiO 2 layer that had formed on the fine Si particles decomposed during nitridation. The maximum strength and fracture toughness of the specimens were 991 MPa and 8.0 MPa•m 1/2 , respectively.

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SRBSN Material Development for Automotive Applications

Cited by 7 publications

References 3 publications

Bridging stresses in sintered reaction-bonded Si3N4 from COD measurements

Bridging stresses in sintered reaction-bonded Si3N4 from COD measurements

Fracture Toughness of a Zirconia Engineering Ceramic and the Effects Thereon of Surface Processing with Fibre Laser Radiation

Densification of Reaction Bonded Silicon Nitride with the Addition of Fine Si Powder - Effects on the Sinterability and Mechanical Properties

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