Sliding wear and friction of Si3N4-SiC-based ceramic composites containing hexagonal boron nitride

1998 ◽  
Vol 212 (5) ◽  
pp. 381-387 ◽  
Author(s):  
R Westergård ◽  
A Åhlin ◽  
N Axén ◽  
S Hogmark
Keyword(s):  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Hexagonal Boron Nitride ◽  
Ceramic Composites ◽  
Wear Behaviour ◽  
Friction Coefficients ◽  
X Ray ◽  
Wear Rates ◽  
Low Level

The friction and wear behaviour of a series of new Si3N4-SiC-based ceramic composites, intended for face seal applications, has been investigated with cylinder-on-disc equipment. In particular, the influence of water and vapour on the friction, wear and tribo-film formation has been studied. The ceramics consisted of Sis3N4 and SiC in the proportions 7:3, to which 0, 4 or 8 wt% of hexagonal boron nitride was added as a solid lubricant. All specimens were produced by hot isostatic pressing. X-ray diffraction and scanning electron microscopy were used to reveal the phase composition and microstructure respectively. The hardness was assessed using Vickers indentation. The chemical composition of the tribo-films was studied with X-ray photoelectron spectroscopy. The major results are that both friction and wear showed distinct low and high levels. The high friction level corresponded to friction coefficients between 0.4 and 0.9 and wear rates between 104 and 105 μm3/Nm. The low level corresponded to friction coefficients between 0.02 and 0.1, and wear rates between 10 and 103 μm3/Nm. When water or saturated vapour was present in the tribo-system, both friction and wear were low. All surfaces produced in the low level were smooth, covered by a thin well-adhering tribo-film while the high level resulted in strongly oxidized and patchy tribo-film covered by wear particles.

Tribological and Corrosion Behavior of HVOF Sprayed Cr3C2-NiCr with Nickel Cladded Graphite and Hexagonal Boron Nitride

2021 ◽  
Author(s):  
M. Oechsner ◽  
T. Engler ◽  
H. Scheerer ◽  
Y. Joung ◽  
K. Bobzin ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Friction And Wear ◽  
Room Temperature ◽  
Solid Lubricant ◽  
Hexagonal Boron Nitride ◽  
Solid Lubricants ◽  
Wear Behaviour ◽  
Wear Volume ◽  
Coating Microstructure ◽  
Sprayed Coatings

Abstract High-velocity oxyfuel (HVOF) sprayed coatings of Cr3C2-NiCr containing solid lubricants such as nickel cladded graphite and hexagonal boron nitride were successfully developed and characterised with the aim of optimizing their friction and wear behaviour. HVOF technology was used for the integration of solid lubricants to achieve strong cohesion between particles while minimizing thermal decomposition. Coating microstructure and composition were measured and correlated to the results of tribological and corrosion tests. The integration of the solid lubricant greatly reduced friction and wear volume at room temperature, but the lubricating effect was highly dependent on atmosphere and temperature. Cr3C2-NiCr with hBN, however, tends to exhibit more stable wear resistance over a wider temperature range and can be used at temperatures beyond 450 °C.

Sonochemical Functionalization of Boron Nitride Nanomaterials

MRS Advances ◽  
2019 ◽  
Vol 5 (14-15) ◽  
pp. 709-716
Author(s):  
Haley B. Harrison ◽  
Jeffrey R. Alston
Keyword(s):  
Thermal Stability ◽  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Colloidal Stability ◽  
Hexagonal Boron Nitride ◽  
Boron Nitride Nanotubes ◽  
Covalent Attachment ◽  
Covalent Functionalization ◽  
X Ray ◽  
Ft Ir

AbstractBoron nitride nanotubes (BNNTs) and hexagonal boron nitride platelets (h-BNs) have received considerable attention for aerospace insulation applications due to their exceptional chemical and thermal stability. Presently, making BN nanomaterials compatible with polymer and composite matrices is challenging. Due to their inert and highly stable structure, h-BN and BNNTs are difficult to covalently functionalize. In this work, we present a novel sonochemical technique that enables covalent attachment of fluoroalkoxy substituents to the surface of BN nanomaterials in a controlled and metered process. Covalent functionalization is confirmed via colloidal stability analysis, FT-IR, and x-ray photoelectron spectroscopy (XPS).

Structural and Chemical Analysis of Hydroxyapatite (HA)-Boron Nitride (BN) Nanocomposites Sintered Under Different Atmospheric Conditions

2017 ◽  
Vol 23 (5) ◽  
pp. 891-899 ◽  
Author(s):  
Feray Bakan ◽  
Meltem Sezen ◽  
Merve Gecgin ◽  
Yapincak Goncu ◽  
Nuran Ay
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Ceramic Composites ◽  
Morphological Properties ◽  
Atmospheric Conditions ◽  
Hard Tissue ◽  
X Ray ◽  
Dental Applications

AbstractCalcium phosphate derivatives have been widely employed in medical and dental applications for hard tissue repair, as they are the main inorganic constitution of hard tissue; such as bones and teeth. Owing to their excellent osteoconductive and bioactive properties, hydroxyapatite- (HA) based ceramics are the best candidates of this group for medical, bioscience, and dental applications. However, when replacing a bone or tooth, HA is not able to sustain similar mechanical properties. In this study, to improve the mechanical properties, nanoscale hexagonal boron nitride with different compositional percentages was added to the nano HA to form composites. The effect of compositional changes and sintering parameters on microstructural and morphological properties of the ceramic composites was comparatively investigated. Detailed chemical characterization of the composite materials was carried out using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy, whereas scanning electron microscopy and atomic force microscopy investigations were employed to monitor morphological and surface features. Additional transmission electron microscopy investigations were carried out to reveal the nanostructure and crystal structure of the composites.

X-Ray Studies of Near-Frictionless Carbon Films.

2004 ◽  
Vol 843 ◽  
Author(s):  
Nikhil J Mehta ◽  
Sujoy Roy ◽  
Jacqueline Anne Johnson ◽  
John Woodford ◽  
Alexander Zinovev ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Close Correlation ◽  
Carbon Films ◽  
X Ray ◽  
Wear Rates ◽  
Wide Range ◽  
Friction Measurements

ABSTRACTCarbon-based coatings exhibit many attractive properties that make them good candidates for a wide range of engineering applications. Tribological studies of the films have revealed a close correlation between the chemistry of the hydrocarbon source gases and the coefficients of friction and wear rates of the diamond-like carbon films. Those films grown in source gases with higher hydrogen-to-carbon ratios had much lower coefficients of friction and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The mechanism for this low friction is as yet not properly understood. Ongoing structural characterization of the films at Argonne National Laboratory is gradually revealing this mechanism. Recent studies have included x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS) and x-ray reflectivity (XRR). XPS showed ∼10% oxygen at the surface, which was largely removed after a 1 minute sputter; NEXAFS showed a high sp2:sp3 ratio implying a highly graphitic material; and XRR has given a comprehensive depth profile, with three layers of increasing density as the substrate was approached. The paper discusses the results and correlation with previous friction measurements.

Microstructure and Chemical Composition of Boron Nitride Fibers

2013 ◽  
Vol 591 ◽  
pp. 16-19 ◽  
Author(s):  
Ru Li ◽  
Chuan Shan Li ◽  
Jie Tang ◽  
Jian Xin Tang ◽  
Xiao Yong Du ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Hexagonal Boron Nitride ◽  
Energy Dispersive Spectrum ◽  
Test Method ◽  
Ir Absorption ◽  
X Ray Diffraction ◽  
Modified Technique ◽  
X Ray

Boron nitride(BN) fibres were synthesized by modified technique of Economy’s method. The products were characterized by X-ray diffraction (XRD), fourier transform infrared (FT-IR) absorption spectroscopy, field-emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectrum (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that BN fibers were mainly hexagonal boron nitride (h-BN) with diameters of 5-8 μm and the major compositions of BN fibers are B and N with a very small amount of O and C. At last, the chemical composition of samples were determined by the chemical analysis test method like GB/T 16555-2008 and GJB 507-1998.

Strengthening Effect of In-Situ Dispersed Hexagonal Boron Nitride in Ceramic Composites

2006 ◽  
Vol 317-318 ◽  
pp. 163-166
Author(s):  
Guo Jun Zhang ◽  
Hideki Kita ◽  
Naoki Kondo ◽  
Tatsuki Ohji
Keyword(s):  
Grain Size ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
High Strength ◽  
Ceramic Composites ◽  
Strengthening Effect ◽  
Mechanical Shock ◽  
Metallic Particles ◽  
Reactive Hot Pressing

High strength particulate ceramic composites are in general reinforced by strong dispersoids, such as strong ceramic particles (SiC, TiB2, ZrO2, et al) and strong metallic particles (Mo, W, et al). In this work high strength ceramic composites with in-situ synthesized hexagonal boron nitride (h-BN) have been prepared and characterized. As an example, we manufactured mullite-BN composites by reactive hot pressing (RHP) using aluminum borates (9Al2O3·2B2O3 and 2Al2O3·B2O3) and silicon nitride as starting materials. The obtained material RHPed at 1800°C showed a strength of 540 MPa, which was 1.64 times higher than that of the monolithic mullite ceramics. TEM observation revealed that the composite had an isotropic microstructure with a fine mullite matrix grain size of less than 1 μm and a nano-sized h-BN platelets of about 200 nm in length and 60∼80 nm in thickness. The high strength was suggested to be from the reduced matrix grain size and the small toughening effect by the h-BN platelets. In addition, this kind of ceramic composite demonstrates low Young’s modulus that is beneficial to the thermal/mechanical shock resistance, and excellent machinability.

scholarly journals Rhombohedral Boron Nitride Epitaxy on ZrB2

2020 ◽  
Author(s):  
Laurent Souqui ◽  
Justinas Palisaitis ◽  
Naureen Ghafoor ◽  
Henrik Pedersen ◽  
Hans Högberg
Keyword(s):  
Electron Microscopy ◽  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Amorphous Material ◽  
Limited Area ◽  
Sem Images ◽  
Plan View ◽  
Minute Amount ◽  
X Ray ◽  
Rhombohedral Boron

<div>Epitaxial rhombohedral boron nitride films were deposited on ZrB<sub>2</sub>(0001)/4H-SiC(0001) by chemical vapor deposition at 1485 °C from the reaction of triethylboron and ammonia and with a minute amount of silane (SiH<sub>4</sub>). X-ray diffraction (XRD) φ-scans yield the epitaxial relationships of 𝑟−𝐵𝑁(0001)∥𝑍𝑟𝐵2(0001) out-of-plane and 𝑟−𝐵𝑁(1120)∥𝑍𝑟𝐵2(1120) in-plane. Cross-section transmission electron microscopy (TEM) micrographs showed that epitaxial break down of r-BN film occurs approximatively after 10 nm, above which epitaxial growth proceeds only in limited area up to 80 nm of film thickness. Both XRD and TEM demonstrate the formation of carbon- and nitrogen-containing cubic inclusions at the ZrB<sub>2</sub> surface. Quantitative analysis from X-ray photoelectron spectroscopy of the r-BN films shows B/N ratios between 1.30 to 1.20 and an O content of 3 to 4 at.%. Plan-view scanning electron microscopy (SEM) images reveal a surface morphology where an amorphous material comprising B, C, and N is surrounding the epitaxial twinned r-BN crystals. SiH<sub>4</sub> exposure prior to growth was found to reduce the amount of the amorphous phase on the surface. Defects such as pitting were also observed on the ZrB<sub>2</sub> template surface.</div><div><br></div>

scholarly journals Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Yong-Jin Cho ◽  
Alex Summerfield ◽  
Andrew Davies ◽  
Tin S. Cheng ◽  
Emily F. Smith ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
High Temperature ◽  
Molecular Beam Epitaxy ◽  
Boron Nitride ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
Hexagonal Boron Nitride ◽  
Graphite Substrate ◽  
Force Microscopy ◽  
Atomic Force

Abstract We demonstrate direct epitaxial growth of high-quality hexagonal boron nitride (hBN) layers on graphite using high-temperature plasma-assisted molecular beam epitaxy. Atomic force microscopy reveals mono- and few-layer island growth, while conducting atomic force microscopy shows that the grown hBN has a resistance which increases exponentially with the number of layers, and has electrical properties comparable to exfoliated hBN. X-ray photoelectron spectroscopy, Raman microscopy and spectroscopic ellipsometry measurements on hBN confirm the formation of sp2-bonded hBN and a band gap of 5.9 ± 0.1 eV with no chemical intermixing with graphite. We also observe hexagonal moiré patterns with a period of 15 nm, consistent with the alignment of the hBN lattice and the graphite substrate.

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