Strength of additive manufactured alumina

Schlacher, Josef; Harrer, Walter; Mitteramskogler, Gerald; Schwentenwein, Martin; Dänzer, Robert; Bermejo, Raúl

doi:10.1016/j.jeurceramsoc.2020.03.073

Cited by 37 publications

(38 citation statements)

References 15 publications

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“…They had other samples sintered at 1650°C. These samples had densities of 98% with no planar void like defects and ∼10% strength difference between build orientations 10 . Their lowest strength corresponded to specimens loaded perpendicular to the build direction (this would correspond to the vertically oriented builds in the present study).…”

Section: Resultsmentioning

confidence: 75%

“…These specimens had wave‐like features attributed to overexposure at the part edge during printing and defects at the base of these grooves created during the removal of excess slurry. It has hypothesized that these specimens were weakest because they were loaded perpendicular to the axes of the grooves 10 …”

Section: Resultsmentioning

confidence: 99%

“…Additionally, they observed that machining of surface defects could improve mechanical performance. Specifically they noted that removing wave‐like surface features that result from overexposure at the part edge during printing, could improve both Weibull characteristic strength and Weibull modulus 10 …”

Section: Introductionmentioning

confidence: 99%

“…5,9 A challenge with many AM parts, including those made via the LCM process, is the introduction of defects in the interior or surface that can influence the mechanical strength of the printed parts. Schlacher et al 10 observed planar collections of voids in printed flexural four-point bend specimens at the interfaces between subsequent layers. The defects correlated with a decrease in characteristic strength when these specimens were loaded such that the planes were in tension.…”

Section: Introductionmentioning

confidence: 99%

“…Specifically they noted that removing wave-like surface features that result from overexposure at the part edge during printing, could improve both Weibull characteristic strength and Weibull modulus. 10 Another feature of some AM processes is that they can induce texturing of the grains in printed parts. This texturing can create orientation dependent differences in properties such as mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

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Flexural strength of a conventionally processed and additively manufactured debased 94% alumina

Kammler

Cillessen

Ford

et al. 2021

Int J Applied Ceramic Tech

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Mechanical strength of a 94 wt% debased alumina was measured using ASTM-C1161 specimens fabricated via conventional and lithography-based ceramic manufacturing (LCM) methods. The effects of build orientation and a 1500 • C wet hydrogen fire added to the LCM firing sequence on strength were evaluated. A Weibull fit to the conventional flexural specimen data yielded 20 and 356 MPa for the modulus and characteristic strength, respectively. Weibull fits of the data from the LCM specimens yielded moduli between 7.5 and 11.3 and characteristics strengths between 333 and 339 MPa. A Weibull fit to data from LCM specimens subjected to the wet hydrogen fire yielded 14.2 and 376 MPa for the modulus and characteristic strength, respectively. The 95% confidence intervals for all Weibull parameters are reported. Average Archimedes bulk densities of LCM and conventional specimens were 3.732 and 3.730 g/cm 3 , respectively. Process dependent differences in surface morphology were observed in scanning electron microscope (SEM) images of specimen surfaces. SEM images of LCM specimen cross-sections showed alumina grain texture dependent on build direction, but no evidence of porosity concentrated in planes between printed layers. Fracture surfaces of LCM and conventionally processed specimens revealed hackle lines and mirror regions indicative of fracture initiation at the sample surface rather than the interior.

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Section: Resultsmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flexural strength of a conventionally processed and additively manufactured debased 94% alumina

Kammler

Cillessen

Ford

et al. 2021

Int J Applied Ceramic Tech

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Stereolithographic 3D Printing of Ceramics: Challenges and Opportunities for Structural Integrity

et al. 2022

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This article reviews the current activities at the Montanuniversität Leoben on the design, processing, and characterization of 3D printed advanced ceramics using the lithography‐based manufacturing technology. An overview of the challenges and the opportunities offered to improve the mechanical properties of printing ceramics is given. Their brittle failure is analyzed within the framework of linear elastic fracture mechanics, considering specific aspects of additive manufacturing. Several issues associated with the printing process are addressed, such as surface quality, geometry control, influence of printing directions, as well as the need to establish testing protocols for 3D printed parts. Based on the layer‐by‐layer capabilities of the stereolithographic process, bio‐inspired material design concepts are discussed aiming to enhance the mechanical resistance of 3D‐printed ceramics. By tailoring the layer architecture and microstructure of the parts, high strength and fracture resistance may be achieved.

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Ability of x‐ray computed tomography to resolve critical flaw size in laser‐based, paste stereolithography ceramic printing of alumina

Cramer,

Rossy,

Dehoff

et al. 2024

Int J Ceramic Engine & Sci

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Complex alumina parts were printed using vat photopolymerization (VPP), which is a stereolithography‐based additive manufacturing (AM) technique used to shape ceramic preforms, or green parts. The critical flaw size was determined using classical fracture mechanics techniques. The strength and fracture toughness were measured and compared to flaws detected in x‐ray computed tomography (XCT or CT) distributions as well as the fracture surfaces. The strength was lower compared traditionally made alumina, and that is due to layering effects, slurry defects, and printing defects. The critical flaw size from fracture mechanics was 206 µm. XCT has high enough resolution to detect the critical flaw size and much smaller features, where the average flaw size observed in CT scans was around 80–100 µm. The fracture surfaces indicate that flaws causing failure are larger than that of the critical flaw size (∼300 µm), but fracture surfaces do not show definitive features compared to traditionally made ceramics. Since XCT can observe flaws smaller than the critical flaw size, this method can be used as a screening technique.

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Strength of additive manufactured alumina

Cited by 37 publications

References 15 publications

Flexural strength of a conventionally processed and additively manufactured debased 94% alumina

Flexural strength of a conventionally processed and additively manufactured debased 94% alumina

Stereolithographic 3D Printing of Ceramics: Challenges and Opportunities for Structural Integrity

Ability of x‐ray computed tomography to resolve critical flaw size in laser‐based, paste stereolithography ceramic printing of alumina

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