Untitled

Brown, Allen L.; Norton, M. Grant

doi:10.1023/a:1006512904173

Cited by 24 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar range of densities for sintered Al x O y N z ceramics were also reported in Refs [27,[31][32][33]. [41][42][43][44], which is in agreement with our results. The most commonly agreed fact is that AlN is mostly oxidation-resistant at temperatures below 850 • C. The initial oxidation of AlN exhibits a linear behavior and proceeds by formation of discontinuous and thin protective oxide film at the surface.…”

Section: Morphological Investigation Of the Oxidized Powders And Sintered Samplessupporting

confidence: 93%

“…In our XRD diffractograms of the oxidized powders, the signal pertaining to θ-Al 2 O 3 at 30 • , 36 • , and 44 • of 2θ position can only be seen in the oxidized powders at 10 and 20 h' oxidation time. The intermediary aluminum oxide phase, θ-Al 2 O 3 was reported in other studies[41][42][43][44], which is in agreement with our results. The most commonly agreed fact is that AlN is mostly oxidation-resistant at temperatures below 850 • C. The initial oxidation of AlN exhibits a linear behavior and proceeds by formation of discontinuous and thin protective oxide film at the surface.…”

supporting

confidence: 94%

“…Above 1000 • C, the oxidation of the surface occurs abruptly and a thick film begins to form at the surface. Above 1050 • C, the oxidation follows a parabolic trend[42][43][44]. In our experiments, at 900 • C, α-Al 2 O 3 was formed exhibiting a coarse structure on the surface (Figure3).…”

supporting

confidence: 50%

See 2 more Smart Citations

Processing of Al2O3-AlN Ceramics and Their Structural, Mechanical, and Tribological Characterization

et al. 2021

View full text Add to dashboard Cite

The aim of this study is to present a novel, lower sintering temperature preparation, processing, structural, mechanical, and tribological testing of the AlN-Al2O3 ceramics. The precursor powder of AlN was subjected to oxidation in ambient environment at 900 °C for 3, 10, and 20 h, respectively. These oxidized powders were characterized by SEM and XRD to reveal their morphology, phase, and crystal structure. The SEM results showed coarse powder particles and the presence of aluminum oxide (Al2O3) phase at the surface of aluminum nitride (AlN). The XRD analysis has shown increasing aluminum-oxy-nitride conversion of aluminum nitride as the holding time of oxidation increased. The highest percentage of conversion of AlN powder to AlN-Al2O3 was observed after 10 h. Simultaneously the powders were compacted and sintered using the hot isostatic pressing (HIP) under inert environment (N2 gas) at 1700 °C, 20 MPa for 5 h. This led to the compaction and increase in density of the final samples. Mechanical tests, such as bending test and tribology tests, were carried out on the samples. The mechanical properties of the samples were observed to improve in the oxidized samples compared to the precursor AlN. Moreover, applying longer oxidation time, the mechanical properties of the sintered samples enhanced significantly. Optimum qualitative (microstructure, oxide percentage) and quantitative (tribology, hardness, and bending tests) properties were observed in samples with 10-h oxidation time.

show abstract

Section: Morphological Investigation Of the Oxidized Powders And Sintered Samplessupporting

confidence: 93%

supporting

confidence: 94%

See 1 more Smart Citation

Processing of Al2O3-AlN Ceramics and Their Structural, Mechanical, and Tribological Characterization

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The oxygen is initially present as Al 2 O 3 on the surface of the AlN powder grains [13]. A grain coarsening sintering may be very useful in order to decrease the oxygen content of the starting material.…”

Section: Article In Pressmentioning

confidence: 99%

Homoepitaxial seeding and growth of bulk AlN by sublimation

Hartmann

Wollweber

Seitz

et al. 2008

Journal of Crystal Growth

View full text Add to dashboard Cite

“…AlN powder annealed in ambient conditions begins to oxidize at 700°C. The material oxidizes at a linear rate below 1000°C and a parabolic rate above that temperature [27]. Above 1000°C, after an initial increase, the oxidation rate decreases slightly indicating that the surface is completely oxidized [28].…”

Section: 2) Backgroundmentioning

confidence: 99%

High temperature studies of thin film Aluminum Nitride and piezoelectric characterization of mesa structures

Farrell¹

View full text Add to dashboard Cite

Aluminum Nitride (AlN) is a group III-V compound that grows in a hexagonal wurtzite crystal structure and is a popular material for microelectromechanical systems (MEMS) due in part to its piezoelectricity, inertness and tolerance to high temperatures. High temperature stability is an essential characteristic for numerous MEMS applications, so one of the goals of this work is to determine how the material properties of AlN are affected by exposure to high temperatures and harsh environments. 3D AlN devices are also investigated to determine the effect of electric field isolation on the piezoelectric response of AlN. A Rapid Thermal Annealing (RTA) system was used to anneal the AlN films at temperatures up to 1000°C in ambient and controlled environments. The oxygen content of films annealed in an ambient environment was measured along with the piezoelectric coefficient (d 33) to determine the effect of oxygen incorporation on the piezoelectric response of the films. A high temperature test chamber was designed and built for in-situ high temperature piezoelectric measurements of AlN. The results of the ex-situ and in-situ high temperature experiments, the effects of oxidation on the piezoelectric response of AlN, and methods used to protect the films from oxidation are discussed. Typically, a metal layer covering the entire AlN film is used as a top electrode in d 33 measurements. In this work, circular AlN mesa structures, consisting of an AlN layer, with thicknesses between 200-1000nm, between two ~200nm metal layers, have been created. By decreasing the contact size and limiting the surface area of the AlN film, clamping effects are reduced. This configuration also minimizes non-normal electric field lines between the top and bottom contacts and further isolates the d 33 piezoelectric coefficient. The devices are constructed using two different fabrication methods and the piezoelectric and electrical properties have been studied. iii ACKNOWLEDGMENTS I would like to express my deepest gratitude to everyone who made this work possible. First I would like to thank my family, who has provided me with love and support throughout this process. Without them, none of this would be possible. I would like to thank my research advisor, Dr. Korakakis, for his guidance, support, and patience throughout my undergraduate and graduate career. I would also like to thank the other members of my committee, Dr. Famouri and Dr. Cao, who have provided valuable technical guidance. I could not have completed this work without helpful discussions and

show abstract

Untitled

Cited by 24 publications

References 4 publications

Processing of Al2O3-AlN Ceramics and Their Structural, Mechanical, and Tribological Characterization

Processing of Al2O3-AlN Ceramics and Their Structural, Mechanical, and Tribological Characterization

Homoepitaxial seeding and growth of bulk AlN by sublimation

High temperature studies of thin film Aluminum Nitride and piezoelectric characterization of mesa structures

Contact Info

Product

Resources

About